United States
      Environmental Protection
      Agency
Office.of Water
Washington. DC 20460
EPA-822-R-96-003
August 1996
EPA  Technical Support
      Document for the Round
      Two Sewage Sludge
      Pollutants

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       Technical Support Document
for the Round Two Sewage Sludge Pollutants
              Prepared by:

   U.S. Environmental Protection Agency
             Office of Water
     Office of Science and Technology
  Health and Ecological Criteria Division
         With the assistance of:

           Abt Associates Inc.
      Hampden Square - Suite 600
         4800 Montgomery Lane
         Bethesda, MD 20814
     Under Contract No. 68-C3-0332

              August 1996

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                           ACKNOWLEDGMENTS

       This study was prepared by Abt Associates Inc., under Contract Number 68-C3-0332,
 for the U.S. Environmental Protection Agency's Health and Ecological Criteria Division of
 the Office of Water.  The following Abt Associates staff contributed to the analysis, writing,
 editing, and production of this document:

 Elizabeth Fechner Levy            Environmental Scientist
 Susan Egan Keane                Environmental Scientist
 Vicki Hutson                     Technical Reviewer
 Dan McMartin                   Environmental Modeler                    .

 Josh Kanner                      Research Assistant
 Caryl Waggett                    Research Assistant
 Rich Walking                     Research Assistant
 Han Wang                     .   Research Assistant
 Michael Wise                     Research Assistant
 Julie Wormser                    Research Assistant

       Abt Associates staff would like to thank Yogi Patel and Barbara Corcoran for their
 guidance and support as EPA Project Managers at different stages of this project.  We would
 also like to  thank Robert Southworth, Maria Gomez-Taylor, Mark Morris, and Alan Hais of
 the Office of Water for their useful comments and valuable insights on various aspects of this
 study.  In addition, we thank Chuck White of SAIC for his statistical analyses of the National
Sewage Sludge Survey data.

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                           EXECUTIVE SUMMARY

       Section 405(d) of the Clean Water Act requires the U.S. Environmental Protection
 Agency (EPA) to promulgate regulations, including numerical limitations for pollutants that
 may be present in sewage sludge, to protect public health and the environment from any
 reasonably anticipated adverse effects of the pollutants.   The  statute requires EPA to
 promulgate regulations' hi two stages. When the Agency failed to meet the statutory deadlines
 for promulgation of these regulations, several groups sued EPA.  The Agency agreed to
 promulgate the first stage of regulation by  November 1992, and the second stage by
 December 2001.  Under the agreement,  filed hi Federal district court, EPA also agreed to
 identify pollutants that it was considering for regulation in the second stage by November
 1995 (Gearhart et al. v. Browner, Civ. No. 89-6266-HO, D. Oregon).

       Implementation of the  Clean Water Act (CWA) has resulted in higher levels of
 wastewater treatment, leading to both greater pollutant removal from the wastewater before
 discharge and generation of larger amounts of sewage sludge.  Publicly Owned Treatment
 Works (POTWs) currently generate 5.3 million dry metric tons of sewage sludge per year,
 or approximately 47 pounds per person per year.

       A  POTW has a number of alternative practices for the use or  disposal of sewage
 sludge.  These practices include, but are not limited to, land application, surface disposal, and
 incineration.  Approximately 33 percent of the sewage sludge generated by POTWs is Used
 to condition the soil or to fertilize crops grown in the soil.  Approximately ten percent of the
 sewage sludge is placed hi surface disposal units, such as surface impoundments (into which
 liquid sewage sludge is placed), sludge-only  landfills (monofills), and piles  left on land
 surfaces.  Approximately 16 percent of the sewage sludge generated by POTWs is combusted
 in sewage sludge incinerators.  The requirements that have to be met for these practices are
 described  in the Standards for the Use or Disposal of Sewage Sludge (40 CFR Part 503),
 which were published under the authority of section 405(d) of the CWA.  These standards
 are known as the "Round One sewage sludge regulation."  Most of the remaining sewage
 sludge generated by POTWs is co-disposed hi landfills, which have requirements established
 by the Solid Waste Disposal Facility Criteria,(40 CFR Part  258 and Part 503,4).

      In  November  1992, EPA promulgated numerical limits for ten pollutants in sewage
 sludge.   At the same tune, the  Agency promulgated an operational  standard for total
hydrocarbons as a surrogate for limits on organic pollutants hi the exit gas from sewage
sludge incinerators.  EPA is now required to make a determination as to whether  it is
necessary to propose and promulgate a regulation covering a second set of pollutants that may
cause adverse effects to public health or the environment (Round Two).  A candidate list of
pollutants  for the second round of the sewage sludge regulations was provided to the District
Court in Oregon hi May 1993. The final list of pollutants was provided to the District Court
hi Oregon hi November 1995. The purpose of this Technical  Support Document is to provide
information on how both the candidate list and the final list of pollutants for the Round Two
sewage sludge regulation were derived.

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        To select the candidate pollutants for Round Two, a Preliminary Hazard Identification
 study was conducted.  First, pollutants that were detected frequently in sewage  sludge were
 determined by using data from the 1988 National Sewage Sludge Survey (NSSS). Analytical
 results for the 411 pollutants for which samples were analyzed in the NSSS were reviewed
 to determine the frequency of detection for each pollutant.  Pollutants with a frequency of
 detection of less than ten percent were deleted from further consideration for the Round Two
 pollutant list.  There were 254 pollutants that were not detected, and another 69 pollutants
 that had a frequency of detection of greater than zero but less than ten percent. If a pollutant
 had a frequency of detection of ten percent or greater, and had not already been regulated in
 Round One, then scientific literature was reviewed to determine whether there were toxicity
 data for a pollutant.  If  no human health or ecological data were found for a pollutant, no
 further consideration was given to that pollutant for the Round Two list. Based on the results
 of the Preliminary Hazard Identification,  a list of 31 Round Two pollutant candidates  was
 submitted to the District Court hi Oregon in May, 1993.

        The 31 pollutant  candidates identified in the Preliminary Hazard Identification study
 were then evaluated hi a Comprehensive Hazard Identification study to determine the final
 list of pollutants for the Round Two sewage sludge regulation. In the Comprehensive Hazard
 Identification study, a quantitative risk  assessment, including dose-response  evaluation,
 exposure assessment, and risk characterization, was performed.  The goal was to identify
 pollutants that may potentially cause human health or ecological risk for a Highly Exposed
 Individual (HEI).  The risk to the HEI was estimated using a combination of high-end and
 average assumptions designed to give a plausible estimate of the individual risk at the upper
 end of the risk  distribution (e.g.,  above the 90th percentile of the actual  distribution).  In
 general, high-end assumptions were used  to characterize sewage sludge concentrations and
 certain exposure parameters, while  average values were  typically  used to characterize
 use/disposal practices  and  soil  and  meteorological  characteristics.    Sewage  sludge
 concentrations were based on the 95th percentile concentrations of pollutants obtained hi the
 NSSS, with non-detects set equal to the minimum level (e.g., the minimum concentration of
 pollutant that could be measured).

       For land application,  risks were estimated for 15 exposure pathways.  For surface
 disposal, risks were estimated for two exposure pathways, and for incineration, one exposure
 pathway.  If  risk values were greater than  certain thresholds for a given  pollutant  and
 exposure pathway, that pathway was defined  as  "critical" for that pollutant.  The threshold
 for carcinogens  was an individual  risk of  IxlO"4 or higher; for non*carcinogens, a ratio of
 exposure to the Risk Reference Dose of one or greater; and for ecological risk, a Risk
 Quotient of one or greater.  Critical pathways were identified for 12 pollutants. These 12
pollutants were  then evaluated further.  As  a result of this evaluation,  EPA  reported hi
November 1995 to the District Court hi Oregon that it  only was considering proposing
regulation of two pollutants, dioxins/dibenzofurans and coplanar polychlorinated biphenyls,
in Round Two.

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                        TABLE OF CONTENTS


 ACKNOWLEDGMENTS	 .
                        • • • • •  .......... .....................   i

 EXECUTIVE SUMMARY ...... ..... ...... ....                      „

 TABLE OF CONTENTS ........................ . . •.                iv

 LIST OF EXHIBITS  ............. ; ...I..........,...;..          vii
 LIST OF MATHEMATICAL SYMBOLS
 1.    INTRODUCTION ...
      1.1   BACKGROUND
      1.2   PURPOSE ..... . ..... . . ........ ............        x_3


 2.    ROUND ONE SEWAGE SLUDGE REGULATION                      21
      2.1   DESCRIPTION OF A PART 503 STANDARD  .....]... . .  . .' " .' "  2-1

      2.2   SEWAGE SLUDGE USE OR DISPOSAL PRACTICES .  . .....      2-2
           2.2.1  Land Application ...... ....... .  . .                  2-2
           2.2.2  Surface Disposal ..... ; .....                       2-2
           2.2.3  Incineration .......... .......  ....               2-3

      2.3   DATA GATHERING STUDIES  . . . ____ . .....                2-3
           2.3.1  The 40 City Study . . . . .........  .. .[.... . . . .2-3
           2.3.2  Environmental Profiles and Hazard Indices . ........     .   2-4
           2.3.3  Sewage Sludge Incinerator Field Studies   . .....            2-5
           2.3.4  National Sewage Sludge Survey ...... .....              2-5

      2.4   ROUND ONE POLLUTANTS . . .........                   2.6


3.     CANDIDATE LIST OF ROUND TWO POLLUTANTS                   31
      3.1   SELECTION PROCESS ..... ........ ;.......'.'.'.'.'.'.'.'''  3-1

      3.2   NATIONAL SEWAGE SLUDGE SURVEY POLLUTANTS ........  3-1

     3 . 3   RESULTS OF PRELIMINARY HAZARD IDENTIFICATION
                  ....... ........ .......... ... ............  3_10
          3.3.1  Pollutants Removed from Further Consideration ..........  3-10
          3.3.2  Individual Pollutants Combined Into Classes ...........  3-io
          3.3.3  Frequency of Detection of Pollutants  ......... ......   3.10
                                 iv

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            3.3.4   Available Human Health and Ecological Toxicity Data  ......  3-11
            3.3.5   Pollutant Candidate List for Round Two Regulation  .......  3-12
4.    FINAL LIST OF ROUND TWO POLLUTANTS  ............  ..... 4-1
      4.1   GENERAL APPROACH FOR THE COMPREHENSIVE HAZARD
            IDENTIFICATION  ......... . .  ....... ............... 4-1

      4.2   LAND APPLICATION PATHWAY EXPOSURE METHODOLOGIES .  . 4-4
            4.2.1   Pathway 1 - Ingestion of Crops Grown on Sewage Sludge-
                   Amended Soil  . . .............................  4-10
            4.2.2   Pathway 2 - Ingestion of Crops Grown hi Sewage Sludge-
                   Amended Home Gardens ........................  4-19
            4.2.3   Pathway 3 - Direct Ingestion of Sewage Sludge by Children  . .  4-25
            4.2.4   Pathway 4 - Ingestion of Animal Products Produced From
                   Animals Consuming Forage/Pasture Grown on Sewage Sludge-
                   Amended Soil  ...  ...... .......... .......... . .  4-26
            4.2.5   Pathway 5 - Consumption of Animal Products Produced From
                   Animals That Ingest Sewage Sludge  ............... . .  4-33
            4.2.6   Pathway 6 - Animal Toxicity From Plant Consumption  .....  4-36
            4.2.7   Pathway 7 - Animal Toxicity From Direct Ingestion of Sewage
                   Sludge ............  . ......................  4-38
            4.2.8   Pathway 8 - Toxicity to Plants  ....................  4-40
            4.2.9   Pathway 9 - Toxicity to Soil-Dwelling Organisms .........  4-40
            4.2.10  Pathway 10 - Toxicity to Predators of Soil-Dwelling
                   Organisms  . .......... ....... ...... ... .....  4^1
            4.2.11  Pathway 11 - Human Toxicity Through Inhalation of
                   Particulates Resuspended by Tilling Sewage Sludge ......... 4-45
            4.2.12  Pathway 12 - Ingestion of Fish and Water from Surface Water
                   that Receives Eroded Soil   .......................  4-48
            4.2.13  Pathway 13 - Inhalation of Pollutants Volatilized from Land-  .
                   Applied Sewage Sludge  ............ .......... .....  4-82
            4.2.14  Pathway 14 - Ingestion of Groundwater Containing Leached
                   Pollutants  ..........  ............ . ..........  4-90
            4.2.15  Pathway 15 - Infant Exposure to Pollutants Through
                   Breastfeeding ........... ..... : . .  . . ..........  4-96

     4.3    SURFACE DISPOSAL EXPOSURE METHODOLOGIES ........ 4-103
            4.3.1   Definitions of a Monofill and a Surface Impoundment ..... 4-103
            4.3.2  Methods for the Monofill Prototype . . .............. 4-103
            4.3.3  Methods for the Surface Impoundment Prototype ........ 4-116
            4.3.4  Estimating Human Exposure ................... . . 4-129
           4.3.5  Data Inputs .................. . .  . ........... 4-130
           4.3.6  Modeling of Surface Impoundments hi the Comprehensive
                  Hazard Identification  ......... ... .............. 4-136
           4.3.7  Example Exposure Calculations for Surface Disposal  ...... 4-136

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       4.4   INCINERATION EXPOSURE METHODOLOGIES  .  .	  4-153
             4.4.1   Estimating Emissions of Pollutants from Incinerators	  4-153
             4.4.2   Modeling the Dispersion of Pollutants in Air	  4-154
             4.4.3   Mapping Dispersion and Pollutant Concentrations Onto a
                    Unified Grid  .	  4-154
             4.4.4   Estimating Human Exposure		        4-156
             4.4.5   Data Inputs	  4-156
             4.4.6   Example Calculations for Incineration	 .  4-157

       4.5    RISK CALCULATIONS		;.....  4-158
             4.5.1   Human Health Risk Calculations	  4.153
             4.5.2   Ecological Risk Calculations	  4-165
             4.5.3   Human Health and Ecological Risk Results .	   4-169


 5.     FURTHER ANALYSES OF ROUND TWO POLLUTANTS                 5 1
       5.1    INTRODUCTION	-.-..........,........!"!'''' 5-1

       5.2    POLLUTANTS THAT WARRANT FURTHER CONSIDERATION  . .  . 5-1


 6.     LIST OF POLLUTANTS FOR THE ROUND TWO REGULATION        •  ' -
       SUBMITTED TO THE COURT	                 6_j

 7.     REFERENCES	                                7_j


 APPENDICES

 Appendix A: Analysis of Pollutants Detected Less than Ten Percent of the Time

 Appendix B:  Statistical Analyses of the National Sewage Sludge Survey Data

Appendix C:  Calculation of a  "Square Wave" for the Groundwater Pathway

Appendix D:  Evaluation of Candidate Pollutants for the Round Two Sewage Sludge
            Regulation

      Appendix Dl:  List of 31 Candidate Pollutants for the Round Two Sewage Sludge
                   Regulation Submitted to the Court

      Appendix D2:  Final List of Pollutants for the Round Two Sewage Sludge Regulation
                   Submitted to the Court

      Appendix D3:  Responses to Requests for Data on the Round Two Candidate
                   Pollutants
                                     VI

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                              LIST OF EXHIBITS

 Exhibit 3-1:   Pollutants Analyzed in the National Sewage Sludge Survey	  3-4
 Exhibit 3-2:   Pollutants Regulated in Round One Sewage Sludge Regulation	3-13
 Exhibit 3-3:   Pollutants Combined Into Classes or Removed from Further
              Consideration	  3-14
 Exhibit 3-4:   Pollutants With a Frequency of Detection of Zero Percent in the
              National Sewage Sludge Survey	    3-15
 Exhibit 3-5:   Pollutants With A Frequency of Detection of Less Than Ten Percent in
              the National Sewage Sludge Survey .	  3-19
 Exhibit 3-6:   Pollutants With A Frequency of Detection of Ten Percent or Greater in
              the National Sewage Sludge Survey	3-21
 Exhibit 3-7:   Available Human Toxicity Data  .	  3-23
 Exhibit 3-8:   Available Ecological. Toxicity Data . .	3-25
 Exhibit 3-9:   Pollutants With No Human Health or Ecological Toxicity Data  ......  3-25
              Available	  3-27
 Exhibit 3-10:  Round One Pollutants Included as Potential Candidates For Round Two .  3-28
 Exhibit 3-11:  31 Pollutant Candidates For Round Two Regulation	; .  3-29
 Exhibit 3-12:  Rationale for the Number of Pollutants  Selected as Candidates for the
              Round Two Sewage Sludge Regulation  ...,.,	3-30

 Exhibit 4-1:   95th Percentile Concentrations for Round Two Candidate Pollutants  .... 4-3
 Exhibit 4-2:   Definitions of Exposure Pathways and Highly Exposed Individuals (HEIs) for
              Land Application			4.5
 Exhibit 4-3.:  Average Values for Sewage Sludge Land Application Parameters ...... 4-9
 Exhibit 4-4:  Background Concentrations of Pollutants in Soil  .	 .  4-10
 Exhibit 4-5:  Dietary Assumptions for Pathway 1  ......................  4.13
 Exhibit 4-6:  Available Plant Uptake Slopes for Agricultural Pathway 1 . .	4-15
 Exhibit 4-7:  Available Plant Uptake Slopes for Non-Agricultural Pathway 1	4-17
 Exhibit .4-8:  Dietary Assumptions for Pathway 2	4-19
 Exhibit 4-9:  Available Plant Uptake Slopes, for Agricultural Pathway 2 .........  4-21
 Exhibit 4-10:  Dietary Assumptions for Pathway 4	4-27
 Exhibit 4-11:  Forage/Pasture Uptake Slopes for Agricultural Pathway 4	  4-29
 Exhibit 4-12:  Animal Uptake Slopes for Agricultural Pathway 4  .	4-31
 Exhibit 4-13:  Animal Uptake Slopes for Non-Agricultural Pathway 4 . :	4-32
 Exhibit 4-14:  Dietary Assumptions for Pathway 5  .		4.35
 Exhibit 4-15:  Bioaccumulation Factors for Soil-Dwelling  Organisms	  4-44
 Exhibit 4-16:  Non-Pollutant-Specific Parameters for Pathways 12, 13, and 14   	4-67
 Exhibit 4-17:  Environmental Fate and Transport Parameters	  4-68
 Exhibit 4-18:  Parameters Used to Calculate 
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 Exhibit 4-23: Environmental Fate and Transport Parameters  	   4-132
 Exhibit 4-24: Human Health Toxicity Numbers	 .   4-159
 Exhibit 4-25: Threshold Limit Values for Pollutants  ....."	   4-161
 Exhibit 4-26: Toxicological Reference Values for Mammals  	   4-166
 Exhibit 4-27: Toxicological 'Reference Values for Soil-Dwelling Organisms	   4-169
 Exhibit 4-28: Risk Results for Highly Exposed Individual for Pathway 1 ........   4-170
 Exhibit 4-29: Risk Results for Highly Exposed Individual for Pathway 2	   4-170
 Exhibit 4-30: Risk Results for Highly Exposed Individual for Pathway 3	   4-171
 Exhibit 4-31: Risk Results for Highly Exposed Individual for Pathway 4	   4-173
 Exhibit 4-32: Risk Results for Highly Exposed Individual for Pathway 5	   4-173
 Exhibit 4-33: Risk Results for Highly Exposed Individual for Pathway 6	   4-174
 Exhibit 4-34: Risk Results for Highly Exposed Individual for Pathway 7	  4-175
 Exhibit 4-35: Risk Results for Highly Exposed Individual for Pathway 9	  4-176
 Exhibit 4-36: Risk Results for Highly Exposed Individual for Pathway 10	  4-177
 Exhibit 4-37: Risk Results for Highly Exposed Individual for Pathway 11	  4-178
 Exhibit 4-38: Risk Results for Highly Exposed Individual for Pathway 12	  4-179
 Exhibit 4-39: Risk Results for Highly Exposed Individual for Pathway 13	  4-180
 Exhibit 4-40: Risk Results for Highly Exposed Individual for Pathway 14	  4-181
 Exhibit 4-41: Risk Results for Highly Exposed Individual for Pathway 15	  4-183
 Exhibit 4-42: Risk Results for Highly Exposed Individual for the Surface Disposal
              Pathways	     4-183
 Exhibit 4-43: Risk Results for Highly Exposed Individual for Incineration Pathway     4-184
                                    •     •                                     -
 Exhibit 5-1:   Pollutants with Critical  Land Application Pathways	5-2
 Exhibit 5-2:   Pollutants with Critical  Surface Disposal Pathways	 5-3
 Exhibit 5-3:   Summary of Critical Pathways and HEIs for Inorganic Pollutants	5-4
 Exhibit 5-4:   Summary of Conservative Assumptions hi Critical Pathways	5-5
 Exhibit 5-5:   Measurement Endpoints for Toxicological Reference Values for
              Inorganic Pollutants	[	 5-6

 Exhibit A-l:   Available Human Toxicity Data for 72 Chemicals Detected Less  Than 10
              Percent of the Time	 A-2
 Exhibit A-2:  Agricultural Pathway 3 Analysis for 43 Chemicals with Oral RfD or QJ*
             Values	    A-4
 Exhibit A-3:  Pollutant-Specific Data Required for Pathways 12 and 13  	A-5
Exhibit A-4:  Individual Cancer Risks  for Aldrin/Dieldrin from Pathway 12	A-6
Exhibit A-5:  Individual Cancer Risks  for Aldrin/Dieldrin from Pathway 13	    A-6
                                         vin

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                    LIST OF MATHEMATICAL SYMBOLS

             =     intermediate diffusivity variable defined in Eq. 4-31 (nrVsec),
             =     change in total mass of pollutant hi soil (kg),
  Ar         =     one year,
  fj.a         ~     viscosity of air (g/cm-sec),
  pa         =     density of air (g air/cm3 air),
  Psi         ~-     particle density of sewage sludge (kg sewage sludge/m3 sewage sludge),
 . Pss         =     particle density of sewage sludge-soil mixture (kg/m3),
  Pw         =     density of water (kg water/m3 water),
  
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  C2         =    total concentration of pollutant in solids layer (kg pollutant/m3 solids layer),
  Cg         =    concentration of gaseous pollutant in air-filled pore space (kg pollutant/m3
                   air),                                                            .
  Ca,r>J       =    average concentration of pollutant j in ambient air at the downwind edge
                   of the site (/*g pollutant/m3 ah-),
  Caoti.]      ~    dry weight concentration of pollutant j in eroded soil entering the stream
                   (mg pollutant/kg eroded soil),
  CffJ        =    concentration of pollutant j in fish fillets (mg pollutant/kg fish fillet),
  Q          =    concentration of pollutant hi inflow to the impoundment (kg pollutant/m3
                   sewage sludge),
  Cj          =    concentration of pollutant j in sewage sludge  (mg  pollutant/kg sewage
                   sludge),
  C^         ~    concentration of pollutant hi water leaching from sewage sludge-amended
                   soil (kg pollutant/m3 porewater),
  Cieej       =     average concentration of pollutant j in water leaching from the sewage
                   sludge-amended soil (mg pollutant/L water),
  cmiiifaij     =     concentration of pollutant j in maternal milk (mg pollutant/kg milk fat),
  Ct          —     concentration of sorbed pollutant on sewage sludge-amended soil particles
                   (kg pollutant/kg soil),
  Cstp.j       —     average concentration of pollutant/' hi  water seeping through the bottom
                   of the impoundment (mg pollutant/L water),
 csaf, j       ^     concentration of pollutant/ hi sewage sludge-amended soil eroded from the
                   land application site (mg pollutant/kg sewage sludge-amended soil),
 CSH.J        =     concentration of pollutant/ in surface water (mg pollutant/L water),
 Ct         =    total concentration of pollutant hi bulk  sewage sludge-amended soil (kg
                  pollutant/m3 total bulk soil volume),
 C*         =    concentration of dissolved  pollutant  hi water-filled  pore space  (kg
                  pollutant/m3 porewater),
 Cwet.        ~    concentration of pollutant/ hi well water (mg pollutant/L water),
            =    concentration of pollutant j  in annual product k (mg  pollutant/kg animal
                  tissue),
            —    tissue concentration  (dry weight) of pollutant j  in  forage/pasture (mg
                  pollutant/kg forage/pasture),
            =    tissue concentration (dry weight) of pollutant/ hi crop / (mg pollutant/kg
                  crop tissue),
            =    tissue concentration  (dry weight)  of pollutant/  hi  forage/pasture (mg
                  pollutant/kg forage/pasture),
            =     incremental cancer risk from pollutant/ for exposed individual (incremental
                  risk of developing cancer per lifetime of exposure),
            =     concentration of pollutant/ hi sewage sludge-amended soil (mg pollutant/kg
                 •sewage sludge-amended soil),
d •         =     depth of incorporation of sewage sludge (cm),
d,          =     depth of liquid layer (m),            •  '    •
d2          =     depth of solids layer (m),
4>          =     depth of aquifer (m),
dc          =     depth of soil cover (m),

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  'de          =     average rate of soil loss due to erosion from sewage sludge-amended land
                    each year (m/yr),
  dm/         ~     depth of a monoflll active sewage sludge unit (m),
  dsi          =     total depth of impoundment (m),
  Df         =     anti-dilution factor (dimensionless),
  D™g        =     geometric mean of the maximum dispersion ratios for 172 incinerators (/*g
                    pollutant/m3 air per g pollutant/sec),
  Dca         -     molecular diffusivity of pollutant in air (cmVsec),
  DC*         =     diffusivity of pollutant in  water (cm2/sec),
  Dei         •=    intermediate diffusivity  variable defined in Eq. 4-30 (m2/sec),
  Dah         =    diffusivity of diethyl ether in water (cnrVsec),
  Df ..        =    dilution factor (dimensionless),
  D'p          =    dispersion ratio for grid cell z impacted by incinerator p (fig pollutant/m3
                   air per g pollutant/sec),
  DAk        =    daily dietary consumption of  animal product k (g dry weight animal
                   product/day),
  DCt        =    daay dietary consumption of crop / (g crop tissue/day),
  de         =    effective diameter (or fetch) of surface impoundment (m),
  DE     ,    =    exposure duration adjustment  (number of years of exposure divided by
                   expected lifetime  of 70 years),
  DV         =    rate of change in  the volume of the liquid layer (m3 liquid layer/sec),
  Eavg.j       =    average emission  rate for pollutant/'(g pollutant/sec),
  EJP         =    emission rate for pollutant j at incinerator p (g pollutant/sec),
  ED         =     exposure duration (yr),
  EXPfJ      =     exposure to  pollutant j through ingestion of fish (mg pollutant/kg body
                   weight-day),
  EXPy       =     exposure to pollutant./ for individuals.living in grid cell i (mg pollutant/kg
                   body weight-day),
 EXP;        =     exposure to pollutant/ (mg pollutant/kg body weight-day),
 EXP*.J      =    exposure  to  pollutant j  through direct ingestion of surface  water (mg
                  pollutant/kg body  weight-day),
 EXPAj      =    exposure of animal to pollutant/ (mg pollutant/kg diet),
 EXPIj       =    infant's average daily exposure to pollutant/ (mg pollutant/kg body weight-
                  day),
 EXPOj     =    exposure of soil-dwelling organisms to pollutant/ (mg pollutant/kg sewage
                  sludge-amended soil),
 EXPTj      =•    exposure of tractor operator to pollutant/  (mg pollutant/m3 air),
f*-J         =    proportion of ingested pollutant/ that isi stored in fat (dimensionless),
f*          =    proportion of mother's weight that is fat  (kg maternal fat/kg total body
                  weight),.
fs          =     proportion of fat in breast milk (dimensionless),
&• J- •        =     proportion of ingested pollutant / that is absorbed (dimensionless),
ft          =     fraction   of  total   pollutant  lost  during  monofill's  active  lifetime
                  (dimensionless),
faa          =     fraction of each year's loading  of pollutant lost during each year of the
                  surface impoundment's active phase (dimensionless),
                                          XI

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  fcg         =     fraction of monofill's active lifetime that typical active sewage sludge unit
                    contains sewage sludge with temporary soil cover (dimensionless),
  fdi         =     fraction of total pollutant in liquid layer that is dissolved (dimensionless),
  jfo         =     fraction of total pollutant in solids layer that is dissolved (dimensionless),
  fte         =     fraction  of "total pollutant  loss  during  monofill's  active  operation
                    attributable to degradation (dimensionless),
  ftteg         —     fraction of total pollutant loss caused by degradation (dimensionless),
  fjqj        =     fraction of total pollutant lost  from liquid layer that is lost to degradation
                    (dimensionless),                                                  .
  fdeg2        =     fraction of pollutant reaching the  solids layer  that is lost  to degradation
                    (dimensionless),
  faeti         = ,    fraction of total pollutant lost from the  liquid layer  as a result of the
                    diminishing volume of the liquid layer (dimensionless),
  fdta         =     fraction of pollutant reaching the solids  layer  that  is  stored  in the
                    accumulating  depth of this layer (dimensionless),
  fen         =     fraction of total pollutant loss caused by erosion (dimensionless),
  fia          =     fraction of  total  pollutant  loss   during monoflU's  active  operation
                    attributable to leaching (dimensionless),
  ftfc   .      =     fraction of total pollutant loss caused by leaching (dimensionless),
"  fig         ==     fraction of total cumulative loading lost in individual's lifetime to all four
                    loss processes (dimensionless),
  fa.          =     fraction of organic carbon (dimensionless),
  fout        =     fraction of total pollutant lost from the  impoundment through outflow
                    (dimensionless),
  foiai        =    fraction of total pollutant lost from  liquid layer that is lost in outflow from
                   the impoundment (dimensionless),
 fsep        =    fraction of total pollutant lost from the  impoundment through seepage
                   (dimensionless),
 ftepi        ~.    fraction of total pollutant  lost from liquid layer that is lost to seepage
                   (dimensionless),
 fsepz        =    fraction of pollutant reaching the  solids layer that is lost to seepage
                   (dimensionless),
 fst          =    fraction of monofill's volume containing sewage sludge (dimensionless),
 fsoi         =    fraction of solids in sewage sludge  (kg solids/kg sewage sludge),
 fun         =    fraction of monofill's active  lifetime that a typical active sewage sludge
                   unit contains sewage sludge without soil cover (dimensionless),
 fva          =    fraction  of total   pollutant  loss  during  monofill's  active operation
                   attributable to  volatilization (dimensionless),
 Jw          =    fraction of total pollutant loss from  inactive  monofill attributable to
                   volatilization (dimensionless),
 /vir         =     fraction of pollutant mass  that  volatilizes  over  a  human  lifetime
                   (dimensionless),
 fvoi         —     fraction of total pollutant loss caused by volatilization (dimensionless),
 frit         =•     fraction of total pollutant lost  from liquid layer that is lost to volatilization
                   (dimensionless),
                                           xu

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   F*    .     =     the volume of fluid passing through a vertical cross-section of the aquifer
                    oriented perpendicular to the direction of flow (m3/sec),
   FAk        =     fraction of dietary consumption of animal product k produced on sewage
                    sludge-amended soil (dimensionless),                            ~
   FAUc       =     annual average flux of pollutant leached from sewage sludge-amended soil
                    (kg pollutant/ha-yr),
   FAUcJ      =     annual average flux of pollutant./ leaching (kg pollutant/ha-yr),
   FAvolJ      =     annual average flux of pollutant J  volatilizing from the sewage sludge-
                   amended soil (kg pollutant/ha-yr),
  Fq         =    fraction of dietary consumption of crop /grown in sewage sludge-amended
                   soil (dimensionless),
  FD        =    fraction of diet considered to be  soil organisms (dimensionless, kg soil
                   organisms/kg diet),
  FM        =    pollutant-specific food chain multiplier (dimensionless),
  F&        -    ratio of fetch to depth (dimensionless),
  FS        =    fraction of animal's  diet that is sewage sludge (dimensionless, kg sewage
                   sludge/kg diet),
  H          =    Henry's Law constant (dimensionless),
  H          =     Henry's Law constant (atm-m3/mol),
  hj '        =     half-life of pollutant j in adults (days),
  IA    •   .   =  - .  inhalation rate (m3 air/day),
  IF          =     daily consumption of fish fillets (kg  fish fillets/day),
  IM       •=     higestion rate of breast milk (kg milk/day),  ,
  IS          =     sewage sludge higestion rate (g sewage sludge/day),
 Tw          =    volume of water ingested daily (L water/day),
 Ki          =    soil-water partition coefficient (L water/kg soil),
 K**        =    loss rate due to abiotic or microbial degradation of the pollutant on-sewaee
                  sludge-amended land (yr1),
 Kdegi       =    anaerobic rate of pollutant degradation in liquid layer (sec'1),
 JW       -    anaerobic rate of pollutant degradation hi solids layer (sec-1)'
   m        ~    Ioss1 rate due to erosion of the pollutant from sewage sludge-amended land

 Kg         =    mass transfer coefficient for the gas layer (m/sec),
 A"/         =     mass transfer coefficient for the liquid layer (m/sec),
 Kte         ~     l°ss rate due to leaching of the pollutant (yr1),
 KOC        =     organic carbon-water partition coefficient (mLwater/g organic carbon)
 A*.        -    octanol-water partition coefficient (dunensionless, mg pollutant/L octan'ol
                 per mg pollutant/L water),
 Kta        =    total loss rate  of pollutant due to leaching, volatilization, and degradation
                 during monofilFs active operation (yr1),
Kti        =    total loss rate  of pollutant from inactive monofill^yr1),
Km,        =  •  total loss rate  for the pollutant from sewage sludge-amended lancl (yr1)
A-.,        =    coefficient for the total rate at which pollutant is lost from the liquid layer
                 of a surface impoundment (mVsec),                '
                 coefficient for the total rate at which pollutant is lost from or stored in the
                 solids layer of a surface impooundment (mVsec),
*-totl
                                         Xlll

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              =     loss rate of pollutant due to volatilization during monofill' s active operation
                    (yr1),
              =     loss rate of pollutant  due to volatilization from inactive monofill (yr1),
              =     loss rate due to volatilization of the pollutant from sewage sludge-amended
                    lander1),
  KVOII        —     rate of pollutant volatilization from liquid layer (m/sec),
  LF         =     active lifetime of monofill (yr),
  LS         =     average human lifetime (yr),
  mbce*growui.f  =     maternal intake of pollutant/ from sources other than sewage sludge (mg
                    pollutant/kg body weight-day),                          .      '   ,
  Mmg        =     geometric  mean of. sewage sludge  feed rates  for  172  incinerators (kg
                    sewage sludge/yr),
  MO,         =     mass of gaseous pollutant (kg),
  Ma         =     mass of sorbed pollutant (kg),     .
  Ma         =     total mass of pollutant hi soil (kg),
  MC,,         =     mass of dissolved pollutant (kg),
  MEsile       =     rate of soil loss for land treated with sewage sludge (kg  sewage sludge-
                    amended soil/ha-yr),
  MEm       =     estimated rate of soil  loss (erosion) for the watershed (kg  soil/ha-yr),
  Mff         =     mass of pollutant in sewage sludge/soil at end of monofill's active lifetime
                    (kg pollutant/ha),
  MIS        =    mass °f pollutant hi soil at end of a period equal to an individual lifetime
                   (mg pollutant/ha);
  Mp         =    mass of sewage sludge incinerated at incinerator p each year (kg sewage
                   sludge/yr),
  Ms         =    mass of soil (kg),
  MS        =    mass of soil in mixing zone of one hectare of land (Mg soil/ha land),
  msiudge.j     =    maternal  intake  of pollutant j  from relevant sewage  sludge exposure
                   pathways (mg pollutant/kg body weightrday),
  MW        =    molecular weight of pollutant (g/mol),
  n          =    number of incinerators modeled,
,  N          =    total number of years  sewage sludge is applied to land (yr),
  Nsaf        =    site life (yr),
  No.         =    total average emissions from  the  soil surface over tune  interval te (kg
                   pollutant/m2 soil),
  Nas        =    emissions from the soil surface in first second (kg pollutant/m2),
  Nay        =•    total average emissions from the soil surface hi first year (kg pollutant/m2),
  NR         =    annual recharge   to   groundwater  (m3 recharge/m2  area-yr,  or  m
                   recharge/yr),
  PI   •      =    fraction of solids (by mass) in liquid layer (kg solids/kg liquid layer),
  P2          =    fraction of solids (by mass) in solids layer (kg solids/kg solids layer),
  Pf          —    ratio of pollutant concentration in fillet to whole fish (dimensionless),
             =    intake level of pollutant/ hi insectivorous mammal's diet (mg pollutant/kg
                   diet),
             =    tune-weighted  average pollutant flux from typical monofill unit over the
                   active lifetime  of the monofill (kg pollutant/m2 unit-sec),
                                           xiv

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  %         -     pollutant flux from treated soil for covered period (kg pollutarit/m2-sec)
  qJ          =     human cancer potency of pollutanty (mg pollutant/kg body weight-day)-'
  ?««         =     pollutant flux  from  sewage sludge/soil  for uncovered  period  (kg
                   pollutant/m2 unit-sec),
  Qi          =     rate at  which  sewage  sludge  enters  the  impoundment  (m3 sewage
                   sludge/sec),                                                       &
  Qo          =     rate at which outflow leaves the impoundment (m3 sewage sludge/sec),
  QW        =     rate of seepage beneath the impoundment (m/sec),
  r'          =     distance from center of the land application site to the downwind edge (m)
  R          =     gas constant (L-atm/mol-K),
  RJ          =     combined removal efficiency for pollutanty of furnace and control devices
                  expressed as fraction of original pollutant mass retained by the furnace or
                  pollution control devices (dimensionless),
 RJP         =    combined removal efficiency for pollutanty of furnace and control devices
                  for  incinerator p expressed as fraction of original pollutant mass  retained
                  by the furnace or pollution control devices (dimensionless),
                  Risk Reference Dose for pollutanty (mg pollutant/kg  body'weight-day)
                  ratio of the exposure to the RiD for pollutanty (dimensionless),
tun
                  ecological risk quotient for pollutanty (dimensionless),
 RTCj       =    ration of the exposure to the TLV-TWA for pollutant y (dimensionless),
 ^i   .   '.'  —    concentration of solids in liquid layer (kg/m3),
 "V         =    concentration of solids hi solids layer (kg/m3)'                        ~
 ScG         =    the Schmidt number on the gas side (dimensio'nless),
 SSM         =    sediment delivery ratio for the land application site (dimensionless)
 ^         ~    sediment delivery ratio for the watershed (dimensionless),
 SC         =    estimated  mass of sewage sludge contained  in one hectare of completed
                .  monofill (kg/ha),                                              F
 SRR       =    source-receptor ratio (sec/m),
 t           =    time (yr),
            =    duration of emissions (sec),
                  time that a typical active sewage sludge unit contains uncovered sewage
                  sludge (yr),                                                       *
            =    temperature (Kelvin),
            =    total exposure of tractor operator to soil dust (mg soil dust/m3 air)
 TF         -    estimated active lifetime of surface impoundment (sec)
 TLV-TWAj  =    Threshold  Limit Value-Time  Weighted  Average  for pollutant / (mg
                  pollutant/m3 air),
 TP         =     duration of "square wave" for approximating the loading of pollutant into
                  the unsaturated soil zone (yr),
 TPN        =     total mass of pollutant available at a site after the final year of application
                  (mg pollutant/ha),                                    .
 TRVj        =    toxicological  reference value for pollutanty for an animal (mg pollutant/kg,
                 diet),
 TSS       =    concentration of total suspended solids in the stream (mg solids/L water)
u          =    average wind speed (m/sec),                                         '
u">         =    average wind speed 10 m above surface (m/sec),
                                        xv

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    forage, j   =    rate °^ uptake of pollutant j into tissue of forage/pasture (mg pollutant/kg
                  dry weight forage/pasture per mg pollutant/kg soil),
            =    rate of uptake of pollutant y into tissue of crop / (jig pollutant/g dry weight
                  crop tissue per /zg pollutant/g sewage sludge-amended soil),
 Ujf.        =    rate of uptake of pollutant j into  animal product k (mg pollutant/kg dry
                  weight animal tissue per mg pollutant/kg dry weight diet),
 v          =    vertical term for dispersion of pollutant hi air (dimensionless),
 vh         =    regional velocity of horizontal groundwater flow (m/sec),
 vt          =    superimposed radial  velocity  from  water, seeping from impoundment
                  (m/sec),
 vv         =    vertical velocity due to the source (m/sec),
 Va         =    volume of air in soil (m3),
 Vs         =    volume of solids in soil (m3),
 V,         =    total bulk volume of soil (m3),
 Vw         =   .volume of water in soil (m3),
 x          =    distance from the center of the land application site  to the downwind edge
                  (km),
•xy          =    lateral virtual distance to land application site (m).
                                          XVI

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                                1.  INTRODUCTION

             Under section 405(d) of the Clean Water Act, the U.S. Environmental Protection
  Agency (EPA) is  required  to  promulgate regulations to protect  public health and  the
  environment from any reasonably anticipated adverse effects of pollutants in sewage sludge
  In November 1992, limits were promulgated for ten pollutants in sewage sludge.  At the same
  time, an operational standard was  promulgated for total hydrocarbons as a surrogate  for
  organic pollutants in the exit gas from sewage sludge incinerators. EPA is now required to
  propose and promulgate a regulation covering a second set of pollutants that may cause
  adverse effects to public health or the environment.


  1.1       BACKGROUND

            Congress adopted the Clean Water Act (CWA)  to "restore and maintain the
  chemical, physical, and biological integrity of the Nation's waters" (section 101(a) 33 U S  C
  1251(a)).  To achieve this goal, the CWA prohibits the discharge of pollutants into navigable
  waters  except in compliance with  the  statute.   The CWA  directs EPA to  promulgate
  regulations that  establish limits  on  the types and amounts of pollutants discharged from
  various industrial, commercial, and  public sources of wastewaters.  In addition  the CWA
  requires EPA  to promulgate regulations  limiting pollutant discharges to sewers'flowine to
  Publicly Owned  Treatment Works (POTWs).                                      .    _

            POTWs provide treatment to domestic sewage and other wastewaters- the effluent
 is generally discharged to surface waters and the residual material (i.e., sewage sludge) may
 be used as a fertilizer or soil nutrient or disposed  by a number .of practices.  Sewag? sludge
 is mostly water (approximately 90 percent), but also contains solids and dissolved substances
 The chemical and biological constituents in sewage sludge depend on the composition of the
 wastewater .that enters the treatment  works  and the processes used to treat the wastewater
 Typically, constituents of sewage sludge include organic chemicals, organic solids nutrients'
 inorganic chemicals, and disease-causing organisms or pathogens Ce.gi, bacteria, viruses and
 neimmth ova).

           Implementation of the CWA has resulted in higher levels of wastewater treatment
 leading to both greater pollutant removal from the wastewater before discharge and generation
 of larger amounts of  sewage sludge.  In the United States, the amount of sewage sludge
 generated  has  almost doubled  since  enactment of  the  Water  Pollution Control Act
 Amendments in 1972. POTWs currently generate 5.3 million dry metric  tons  of sewage
 sludge per year, or approximately 47 pounds per person per year.  Proper management of the
 use or disposal  of the  sewage sludge is important.

           A POTW has a number of alternative practices for the use or disposal  of sewage
 sludge. These practices include, but  are not limited to, land application, surface disposal
placement in a municipal solid waste landfill, and incineration: The requirements that have
to be met for all of these practices are described in the Standards for the Use or Disposal of
Sewage Sludge  (40 CFR Part 503), which were  published under the authority of section
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  405(d)  of the CWA.   These  standards are known as the  "Round One sewage sludge
  regulation."

            The Federal Water Pollution Control Act Amendments of 1972 regulated sewage
  sludge use or disposal  in only one limited circumstance: when the use or disposal poses a
  threat to navigable waters.  Section 405(a)  of the CWA prohibited the disposal of sewage
  sludge if it would result in any pollutant from the sewage sludge entering navigable wasters
  unless  hi accordance with a permit issued by the EPA  Administrator.  In 1977, Congress
  amended section 405 to add a new subsection 405(d) that required EPA to develop regulations
  for the use or disposal of sewage sludge. The regulations  had to establish guidelines that:
  (1) identify uses for sewage sludge, including disposal;  (2) specify factors to  be taken into
  account hi determinhig the methods and practices applicable to each use or disposal practice;
  and (3) identify concentrations of pollutants that interfere with each use or disposal practice.

            In 1987, Congress amended section 405 again and for the first tune set forth a
 comprehensive program to reduce the potential public health and environmental risks from
 sewage sludge and to maximize the beneficial use of sewage sludge. Amended section 405(d)
 established a timetable for the development of the sewage sludge use or disposal guidelines.
 The basis for the program Congress mandated to protect public health and the environment
 is the development of technical requirements or standards for sewage sludge use or disposal
 and the implementation of the standards, in part through a permit program.

           Under the current section 405(d), EPA must first  identify, based on available
 information, toxic pollutants that may be present in sewage sludge in concentrations that may
 adversely affect public health and the environment.  Next, for each identified use or disposal
 practice,- EPA must promulgate regulations that specify acceptable management practices and
 numerical limits for sewage sludge that contains these pollutants. The management practices
 and numerical limits must be "adequate to protect public health and the environment from any
 reasonably anticipated adverse effects of each pollutant. "  Section 405(d) requires that EPA
 promulgate the sewage sludge  regulations  in  two rounds  and review  the regulations
 periodically to identify additional toxic pollutants for regulation.

           On February 19, 1993, EPA published the Round One sewage sludge regulation
 in the Federal Register (58 FR 9248).   Subsequently, the regulation was amended on
 February 24, 1994 (59 FR 9095)  and on October 25, 1995 (60 FR 54764).

           A  candidate- list  of  pollutants for the  second round  of the sewage  sludge
 regulations (i.e., Round Two) was developed hi May 1993 in accordance with an agreement
 filed with the District Court hi Oregon (Gearhart et al. v. Browner, Civ. No. 89-6266-HO,
 D.  Oregon).   The final list of pollutants was provided to the District Court in Oregon in
 November 1995, and the Round Two regulation is scheduled  for proposal .hi December 1999
 and for publication hi December 2001 . The Round Two regulation will be an amendment to
the Round One regulation.
                                                                                          €>
                                        1-2

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1.2    PURPOSE
       The purpose of this document is to provide information on the list of pollutants for
the Round Two sewage sludge regulation.  It discusses the Round One regulation (Chapter
2), describes the methodology used to evaluate pollutants for inclusion on the candidate list
of Round Two pollutants and presents the candidate list of Round Two pollutants (Chapter
3), describes the methodology used to develop the final  list of Round Two  pollutants
(Chapters 4 and 5), and presents the final list (Chapter 6).
                                      1-3

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            2. ROUND ONE SEWAGE SLUDGE REGULATION
  2.1        DESCRIPTION OF A PART 503 STANDARD

            The Round One sewage sludge regulation established standards for the use or
  disposal of sewage sludge when the sewage sludge is applied to the  land (including sewage
  sludge sold or given-away in a bag or other container for application to the land), placed In
  a surface disposal site, placed in a municipal solid waste landfill, or incinerated. In general.
  the rule does not apply to the processing of sewage sludge before use or final disposal.

            A Part 503  standard contains seven  elements: general  requirements, pollutant
 .limits,  management  practices,  operational  standards,  and  frequency  of  monitoring.
  recordkeeping,  and reporting requirements.  These elements are designed to protect public
  health and the environment (only public health was evaluated in the case of incineration) from
  the reasonably anticipated adverse effects of pollutants in sewage sludge.

           The general  requirements hi a Part 503 standard contain what are  often called
  "administrative  requirements."  For example, the general requirements for land application
 require  the preparer of the sewage  sludge to  notify  the permitting authority about  the
 interstate transfer of sewage  sludge that is land applied.  Without the general requirements.
 a Part 503 standard  is  incomplete.  Thus, it is important that the regulated  community
 understand and follow the Part 503 general requirements. Note that the general requirements
 are different for land application, surface disposal, and incineration.

           Specific pollutant limits are established separately for  each regulated  use or
 disposal practice. EPA developed these limits based on the results of a risk assessment.  For
 example, in the  case of land  application, up to 14 exposure pathways were evaluated in the
 risk assessment for each pollutant.  The most stringent value for all of the exposure pathways
 for a  pollutant  was used to determine the limit for that pollutant  in  the  Part 503 land
 application subpart.

           Management practices  contain requirements that have to be met at a  use  or
 disposal  site, or, in the case of incineration, requirements for the incinerator.  For example,
 one of the surface disposal management practices indicates that to protect public health, food
 crops  cannot  be grown on  a surface disposal  site unless  otherwise authorized by  the
 permitting authority.

           Operational standards are technology-based requirements that in the judgement of
 the EPA Administrator protect public health and the environment.  Section 405(dX3) of the
 CWA  indicates that when risk-based pollutant limits and management practices cannot  be
developed, requirements such as an operational standard can be utilized. For land  application
and  surface  disposal, the pathogen  and  vector attraction -reduction  requirements  are
operational standards.  For incineration, the allowable concentration of total hydrocarbons in
the exit gas from the incinerator stack is an operational  standard.
                                        2-1

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         The final three elements of a Part 503 standard help make the Round One regulation
  self-implementing.  This means that the Part 503 requirements have to be met even in the
  absence of  a federal permit.   The frequency of monitoring requirements  establish  the
  frequency at which sewage sludge samples  have to collected and  analyzed, while  the
  recordkeeping requirements indicate who has to keep what records and  for  how  long.
  Finally, the  reporting requirements indicate who has to report information to the permitting
  authority annually.
  2.2    SEWAGE SLUDGE USE OR DISPOSAL PRACTICES

         This  section discusses the use or  disposal practices for which requirements are
  included  in  the Round One sewage sludge regulation.   These practices include land
  application, surface disposal, and incineration.  These same use or disposal practices were
  evaluated during the development of the final list of pollutants for the Round Two regulation,
  as discussed in more detail in Chapter 4.  Note that the placement of sewage sludge in a
  municipal solid waste landfill is not considered under Round Two, because the requirements
  have already been established by the Solid Waste Disposal Facility Criteria (40 CFR Part 258
  and Part 503.4).

  2.2.1  Land Application                                                       .   ,

        Approximately  33 percent of  the sewage  sludge  generated by POTWs is used to
  condition the soil or to fertilize crops grown in the soil.  Approximately 22 percent  of the
  sewage sludge  generated by POTWs is applied to agricultural land  (including pasture and
  range land). Approximately 11 percent of the sewage sludge generated by POTWs is applied
  to forests,  public contact sites (e.g.,  parks, ball  fields, and highway  median strips), and
  reclamation sites, or is sold or given away in a bag or other container for home gardens. The
  method ofapply ing sewage sludge to the land depends on the physical characteristics of the
  sewage sludge and the soil, and on the types of crops or vegetation grown.  Liquid sewage
  sludge may be  applied to the land surface or may be injected below the land surface.
  Dewatered sewage sludge is usually applied to the soil surface and either is left on the soil
  surface or incorporated into the soil by plowing or disking.

        Ten or more States have undertaken sewage sludge application to forests, at least on
  an experimental field-scale level. The most extensive experience with this practice is in the
 Pacific Northwest.  Usually, partially  dewatered sewage sludge is sprayed onto established
 forest stands using mobile equipment.

        Sewage sludge that is sold or given away in a bag or other container for application
 to the land often is composted with another material or heat-dried. The sewage sludge most
 often is used to fertilize lawns and home gardens.

.2.2.2  Surface  Disposal

        Surface disposal is the term used to describe the placement of sewage sludge on land
 for final disposal.   Surface disposal is used to  describe a number of  different practices,

                                         2-2

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  including disposal in surface impoundments (into which liquid sewage sludge is placed).
  disposal in sludge-only landfills (monofills), and disposal in piles left on land surfaces. These
  practices account for the disposal of approximately ten percent of the sewage sludge generated
  by POTWs.                               ......

  2.2.3      Incineration

            Incineration  is a practice that reduces the volume of sewage sludge through
  combustion.  A sewage sludge incinerator is an enclosed device in which sewage "sludge and
  auxiliary fuel are fired at high temperatures.  During the incineration process, emissions are
  discharged to the atmosphere.  The residual ash that is-generated is not sewage sludge, by
  definition.

            Approximately 16 percent of the sewage sludge generated by POTWs (i.e.,
  865,000 dry metric tons) is fired in a sewage sludge incinerator.  Most of the sewage sludge
  incinerators employ  the multiple  hearth technology.    Other types  of sewage sludge
  incinerators include multiple hearth incinerators with a secondary combustion chamber,
  fluidized bed incinerators, and electric incinerators.
 2.3       DATA GATHERING STUDIES

           The results of several EPA-sponsored data gathering studies were used to support
 development of the Round One sewage sludge regulation. These include the "40 City Study"
 (U.S. EPA,  1982), Environmental Profiles and Hazard Indices (U.S. EPA, 1985), sewage
 sludge incinerator field studies, and the National Sewage Sludge Survey (U.S. EPA, 1990a).
 These studies are described below.

 2.3.1 The 40 City Study

           During 1979 and 1980, EPA conducted a study, known as the "40 City Study"
 (U.S. EPA, 1982), to determine the fate of priority toxic pollutants in POTWs.  Wastewater
 samples were collected at 40 POTWs throughout the United States and analyzed for priority
 toxic pollutants.  Analytical data from the study were used to determine whether priority
 pollutants were in the influent to  POTWs and, if they were, what happened to them as they
 moved through the POTW.

           At several of the POTWs where wastewater samples were collected, sewage
 sludge samples also were collected and analyzed for priority toxic pollutants. Analytical data
 for the sewage sludge samples were used to determine the concentrations of 40 pollutants (12
metals, six base neutral organic compounds, six volatile organic compounds, nine pesticides,
and seven polychlorinated biphenyls)  in sewage sludge.  These concentrations were used to
develop the Environmental Profiles and Hazard Indices discussed below.
                                        2-3

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 2.3.2  Environmental Profiles and Hazard Indices

        In the spring of 1984, EPA enlisted the assistance of Federal, State, academic, and
 private sector experts to determine which pollutants likely to be found in sewage sludge
 should be examined  closely as possible candidates  for Part 503  pollutant limits.   These
 experts screened a  list of  185 pollutants in sewage sludge that,  if used  or disposed
 improperly, could cause adverse public health or environmental effects.  The experts were
 then requested to revise the list, adding or deleting pollutants, based on the potential risk to
 public health and the environment when sewage sludge containing a particular pollutant was
 applied to the land, placed in a surface disposal site, or incinerated.   The Agency also
 requested that the experts identify the most likely route that a pollutant would travel to reach
 target organisms, whether  human, plant,  or animal.  The experts recommended that the
 Agency gather additional information on approximately 50 pollutants. During 1984 and 1985,
 the Agency collected data and information from published scientific reports on the toxiciry,
 persistence, means of transport, and environmental fate of the 50 pollutants.

        EPA made an assessment of the likelihood that each pollutant would adversely affect
 public health  or the environment by using data from the'40 City Study on the frequency of
 detection and concentration of pollutants hi sewage sludge and preliminary information on
 pollutants' toxicity and persistence, the pathways by which the pollutants travel through the
 environment to a receptor organism (human, animal, or plant), the mechanisms that transport
 or bind the pollutants in the pathway, and the effects of pollutants on the target organism.
 For these  analyses, EPA relied on simple screening models and calculations to predict the
 exposure to each .pollutant that would occur if the pollutant were present hi surface or ground
 water, soil, air, or food. EPA then developed a hazard index for each pollutant by comparing
 the predicted exposure to  an Agency human health criterion, such as  a drinking  water
 standard promulgated under the Safe  Drinking Water Act, or an animal or plant toxicity
 number, to determine whether the pollutant could be  expected to have an adverse effect on
 public health or the environment.  For purposes of this initial screening, EPA assumed:  (1)
 conditions that would maximize the exposure of an individual human, animal, or plant to the
 pollutant and (2) the worst possible toxicity effects of the pollutant.

       Using  the hazard indices, EPA scored each pollutant and ranked them  for  more
 rigorous analysis. Two categories of pollutants were excluded from further evaluation.  First,
 EPA excluded pollutants that had a hazard index of less than one (i.e., presented no risk to
 public health or the environment at the highest concentration that the Agency found in the "40
 City Study" or hi other available databases).   Second,  EPA deferred  consideration of
 pollutants for which EPA lacked human health criteria or sufficient data. An environmental
 profile for each pollutant was then developed  by combining environmental fate, transport, and
 toxicity data on each pollutant, the results of the simple screening models and calculations,
 and the hazard indices for that pollutant (U.S. EPA, 1985).  The environmental profiles were
used to determine the pollutants for which limits would be developed through a detailed risk
assessment of exposure pathways.
                                         2-4

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  2.3.3  Sewage Sludge .Incinerator Field Studies

        In 1987, the Agency initiated a series of field studies at ten sewage sludge incinerators
  to support the Part 503 rulemaking effort.  The purposes of the on-site tests were to obtain:
  (1) information about the percentage of hexavalent chromium in the total chromium in the exit
  gas from a sewage sludge incinerator, (2) information on the percentage of nickel subsulfide
  in the  total nickel in the exit gas from a sewage sludge incinerator, (3) total hydrocarbon
  (THC) emissions data for the sewage  sludge incinerators, and (4) information about organic
  compounds hi the exit gas from a sewage sludge incinerator.

        Data from the .studies on the exit gas THC concentrations were used as the basis for
  the THC operational standard hi the Round One sewage sludge regulation.  This  standard is
  technology-based in that it is based on performance data from sewage sludge incinerators
  Test data indicated that there is a significant correlation between THC and organic compound
  concentrations hi the exit gas, which is important because sampling and analysis  techniques
 are not available to identify or quantify all potential organic compounds emitted from sewage
 sludge incinerators, nor are toxicity data available for all compounds.

 2.3.4  National Sewage Sludge Survey

       In  1988, EPA conducted the  National Sewage Sludge Survey (NSSS)  to collect
 information and data necessary to produce national estimates of: (1) concentrations of toxic
 pollutants in sewage sludge, (2) sewage sludge generation and treatment processes, (3) sewage
 sludge use or disposal practices, and (4) sewage sludge  treatment and use or disposal costs.

       The NSSS consisted of a questionnaire survey and an analytical survey  The sample
 for the  questionnaire survey  was selected from the 11,407 POTWs  in the  United States
 Puerto Rico, and the District of Columbia, identified in the 1986 Needs Survey as having at
 least secondary treatment. Secondary treatment was defined as primary clarification followed
 by biological treatment and secondary clarification. The sample for the analytical survey was
 a subset of the sample for the questionnaire survey.

    .  POTWs m me two samples were  selected using a stratified probability design based
on 24 mutually exclusive groups.  Membership in these groups was based on four categories
of wastewater flow rates and six use or disposal practices.  The flow rates and use or disposal
categories were as follows:                                                      v
                                         \
      POTW average daily flow rate categories:                                     ,

             •      Flow rate less than  or equal  to one million gallons per day (MOD)
             •      Flow rate greater than one MGD, but less  than or equal to 10 MOD
             •     Flow rate greater than 10 MGD, but less than or equal to 100 MGD
             •     Flow rate greater than 100 MGD
                                       2-5

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        POTW sewage sludge use or disposal practice groups:

              •      Land application
              •      Distribution and marketing (now called sale or give-away in a bag or
                     other container for application to the land)
              •      Incineration
              •      Monofill (sewage sludge-only landfill)
              •      Co-disposal landfill
              •      Ocean disposal

        For the questionnaire survey, a 50 page questionnaire was mailed to 479 POTWs.
 Information collected through the questionnaire included service area, POTW operating data,
 sewage sludge use or disposal practices,  pretreatment activities,  wastewater  and  sewage
 sludge testing frequencies, and POTW financial information.  In addition to the six use or
 disposal practices used  for  the  stratified sampling,  information was  collected  on co-
 incineration and surface disposal.

        POTWs in the analytical survey were restricted to POTWs  in the contiguous States
 and the District of Columbia.  As mentioned above, the POTWs were a subset  of  the
 POTWs in the questionnaire sample.  Sewage sludge samples were collected at 208 POTWs
 from the four flow rate categories and analyzed for 411 analytes. (Note that in 58 FR 9269,
 it is stated that samples were analyzed for a total of 412 analytes.  In Appendix C-List of
 NSSS Analytes hi the NSSS Data Element Dictionary for the Questionnaire and Analytical
 Data Bases, (U.S. EPA, 1990a), a total of 413 analytes are listed.   However, the pollutants
 crotoxyphos and  phosphorus were listed twice in Appendix  C (crotoxyphos  under both
 semivolatile organics and pesticides/herbicides; phosphorus under both metals and classicals).
 Therefore samples were analyzed for a  total of 411 analytes.)  Results of the NSSS are
 discussed in Chapter 3.
2.4    ROUND ONE POLLUTANTS

       The Round One sewage sludge regulation included limits (or equations for calculating
these limits) for 11 pollutants for one or more use or disposal practices. Not every pollutant
is regulated for each practice.  When the rule was proposed, limits were developed for 28
pollutants for one or more use or disposal practices.  The final Round One regulation contains
limits for the following pollutants:

       Land application:    arsenic, cadmium, chromium (deleted from the land application
                          subpart on  October  25,  1995),  copper,  lead,  mercury,
                          molybdenum, nickel, selenium, and zinc

       Surface disposal:     arsenic, chromium, and nickel

       Incineration:         arsenic,  cadmium,   chromium,   lead,   nickel,   and  total
                          hydrocarbons.  Beryllium and mercury are regulated through a
                          National Emission Standard

                                       2-6

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           3.CANDIDATE LIST OF ROUND TWO POLLUTANTS


  3.1        SELECTION PROCESS

             The Clean Water Act requires EPA to: (1) identify pollutants that may be present
  in sewage  sludge  in  concentrations  that  may  adversely  affect  public  health and  the
  environment,  and (2) promulgate standards, including numerical limits  for the identified
  pollutants.  To select the pollutants  on  the  candidate list of Round Two  pollutants  a
  Preliminary Hazard Identification study was conducted.  The first step in the study was to
  determine the pollutants not regulated  in the Round One sewage sludge regulation  that are
  detected frequently in sewage sludge.  This was done using data from the  1988 NSSS
  Analytical results for the 411 pollutants for which samples were analyzed in the NSSS were
  reviewed to determine the frequency  of detection for each pollutant.  Pollutants with a
  frequency of detection of less than ten percent were deleted from further consideration for
  the Round Two pollutant list, if the results of a toxicity analysis did not indicate potential for
  adverse public health effects (see Appendix A).  If a pollutant had a frequency of detection
  of ten percent or greater, the second step in the Preliminary Hazard Identification study was
  conducted.        .                                        .           -  .   .       .

           In the second step, scientific literature was reviewed to determine whether there
  were  toxicity data for a pollutant.  If no human health or ecological data were found for a
  pollutant, no further consideration was given to that pollutant for the Round Two list.

           Pollutants for  which sewage sludge samples were analyzed in the NSSS are
 presented in Section  3.2.   Section  3.3 presents the  results of the  Preliminary Hazard
 Identification study for pollutants with a frequency of detection of ten percent or greater and
 for which toxicity data were available.                                   .is«*uerdna


 3.2       NATIONAL SEWAGE SLUDGE SURVEY POLLUTANTS

           Sewage sludge samples collected during the NSSS were analyzed for 411 analvtes
 as shown in  Exhibit 3-1 at the end of this section.  These analytes included inorganics a^
 well as eveiy organic, pesticide, dibenzofuran, dioxin, and polychlorinated biphenyl (PCB)
 for which EPA had gas chromatography and mass spectrometry  (GC/MS) standards  The
 pollutants also were selected in consideration of the CWA priority toxic pollutants'" toxic
 pollutants identified in the Domestic Sewage Study (U.S, EPA? 1986a>!  and Resource
 Conservation and Recovery Act (RCRA, Pub. L. 94-580) appendix VIE pollutants.

           Three categories of POTWs were excluded from calculations of national estimates
of pollutant concentrations in sewage sludge: Primary Samples Only, No Sludge Sampled
SSs?? flBusmeAss/Ineligible- ,In addition, data for one POTW were not entered into the
NSSS database.   As a result, data from only 176 of the 208 POTWs sampled were used to
estimate pollutant concentrations.   The rationale  for excluding  the three  categories is
described below:
                                       3-1

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            Primary Samples Onty - Samples of sewage sludge generated during less than
            secondary treatment were collected from some POTWs; for two POTWs, they
            were the only type of sample collected.  These data were not suitable to use in
            determining the national estimates for pollutant concentrations in sewage sludge
            generated during secondary or more-advanced treatment.

            No Sludge  Sampled - No  sewage sludge samples were collected at 24 of the
            selected POTWs. For 18 of those POTWs, pre-sampling phone contacts indicated
            that sewage sludge was not being used or disposed at these POTWs during the
            time  of the NSSS.  These  18 POTWs claimed  to treat their  wastewater in
            stabilization ponds; sewage sludge generated in a stabilization pond remains in the
            pond until it is removed for final use or disposal through some other practice.

            Out of Business/Ineligible - Five of the selected POTWs were either closed or
            could not be contacted by telephone.  Therefore, no data were available for those
            POTWs because no samples could be collected.

            Sewage sludge sampling, preservation, and analytical protocols were developed
 specifically for the NSSS. Analytical methods 1624 and 1625 were developed for volatile and
 semi-volatile organics,  respectively,  hi the sewage sludge matrix; these methods use gel
 permeation chromatography sample clean-up followed by isotope dilution GC/MS analyte
 identification and quantification.  Pesticides and PCBs, and  dibenzofurans/dioxins, were
 analyzed using analytical methods 1618 and 1613, respectively. Metals, other inorganics, and
 classicals were analyzed using standard FJPA  methods.  The analytical methods were
 developed or adapted specifically for the sewage sludge matrix to give the  most reliable,
 accurate,  and precise measurements of the 411 analytes.

           Each  NSSS sample was tested by EPA contract laboratories for 411 pollutants.
 A minimum level, one land of "detection  limit" used by the Agency, was identified for each
 pollutant in the protocol of the analytical method.  That minimum level, as applied to the
 determination of pollutants by GC/MS, is defined by the EPA?s Engineering and Analysis
 Division'in the Office_ of Water as the level at which the entire analytical system shall give
 recognizable mass spectra and acceptable calibration points. In the NSSS, the minimum level .
 is equivalent to the minimum concentration of pollutant that could be measured.

           Pollutant concentrations arid minimum levels were reported in dry weight units
 due to differences hi the percent solids in sewage sludge samples; percent solids ranged from
 less than one percent to 100 percent in NSSS samples.  The use of dry weight units allows
 all sewage sludges to be evaluated on an equivalent basis. Implicit in this form of reporting
 is that pollutants are associated  with the solid phase of sewage sludge.

           For any given pollutant, the minimum levels varied due to varying volumes or
masses of samples tested, dilution of the sample or extract, and matrix effects or interference.
All analytical protocols specified the volume or amount of sewage sludge to be tested. When
matrix interferences prevented accurate determination of pollutant concentrations, however,
samples were diluted  with reagent water  and then reanalyzed.  The minimum level for a
diluted sample was then raised by the dilution factor.  For example, if a sample was diluted

                                        3-2

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by a factor of 10, then the minimum level was raised by a factor of 10.  Analytical protocols
provided explicit guidance as to the limits of dilution.

           For each pollutant, EPA statisticians calculated the frequency of occurrence as
weir as the median and other percentile concentrations.  Non-detected values were treated in
two ways to capture the full range of possible concentrations: nondetects were set to both the
minimum level and  to  zero.  These national pollutant concentration estimates reflect the
distribution  of pollutant concentrations in dry weight sewage sludge that is generated by
secondary or more advanced wastewater treatment at POTWs.  Appendix B provides details
on the statistical analyses performed on the NSSS data.
                                        3-3

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                                   EXHIBIT 3-1
              Pollutants Analyzed in the National Sewage Sludge Survey
  Pollutant1
  Acenaphthene
  Acenaphthylene
  Acetic acid, 2,4-dichlorophenoxy
  Acetophenone
  Acrylonitrile
  Aldrin
  Aluminum
  Aminobiphenyl, 4-
  Aniline
  Aniline, 2,4,5-trimethyl-
  Anisidine, o-
  Anthracene
  Antimony
  Aramite
  Arsenic
  Azinphos ethyl
 Azinphos methyl
 Barium
 Benzanthrone
 Benzene
 Benzenethiol
 Benzidine
 Benzofluorene, 2,3-
 Benzoic acid
 Benzonitrile, 3,5-dibromo-4-hydroxy-
 Benzoquinone, 2,6-di-tert-butyl-p-
 Benzothiazole, 2-(methylthio)
 Benzo(a)pyrene
 Benzo(b)fluoranthene
 Benzo(ghi)perylene
 Benzo(k)fluoranthene
 Benzyl alcohol
 Benz(a)anthracene
 Beryllium
 BHC, alpha-
BHC, beta-
BHC, delta-
Biphenyl
  Biphenyl, 4-nitro
  Bismuth
  Bis(2-chloroethoxy)methane
  Bis(2-chloroethyl)ether
  Bis(2-chloroisopropyl)ether
  Bis(2-ethylhexyl)phthalate
  Boron   -   ,
  Bromodichloromethane
  Bromomethane
  Butadiene, 2-chloro-l,3-
  Butanone, 2-
  Butene,  trans-l,4-dichloro-2-
  Butyl benzyl phthalate
  Cadmium
  Calcium
  Captafol
I Captan
J Carbazole
  Carbon disulfide
  Carbophenothion (Trithion)
  Cerium
  Chlordane
  Chloroacetonitrile
  Chloroaniluie, p-
  Chlorobenzene
  Chlorobenzene, l-bromo-2-
 Chlorobenzene, l-bromo-3-
 Chlorobenzilate
 Chloroethane
 Chloroethylvinyl ether, 2-
 Chlorofenvinphos
 Chloroform
 Chloromethane
 Chloronaphthalene, 2-
 Chlorophenol, 2-
 Chloropropene, 3-
 Chlorpyrifos
 Chromium
                                      3-4

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  Pollutant1
  Pollutant1
  cnrysene                        «
  Ciodrin
  Cobalt
  Copper
  Coumaphos
  Cresol, o-
  Cresol, p-
  Crotonaldehyde
  Crotoxyphos
  Cyanides (soluble salts and complexes)
  Cymene, p-'
  DDD
  DDE
  DDT
  Decane, n-
  Demeton
  Diallate
 Diazinon
 Dibenzofuran

 Dibenzothiophene
 Dibenz(a,h)anthracene
 Dibromochloromethane
 Dibromoethane, 1,2-
 Dibromomethane
 DicMoroaniline, 2,3-
 Dichlorobenzene,  1,2-
 Dichlorobenzene,  1,3-
 Dichlorobenzene,  1,4-
 Dichlorobenzidine, 3,3'-
 Dichloroethane, 1,1-
 Dichloroethane, 1,2-
 Dichloroethene, 1,1-
 Dichloroethene, trans-1,2-
 Dichloronitrobenzene, 2,3-
 Dichlorophenol, 2,4-
 Dichlorophenol, 2,6-
 Dichloropropane, 1,2-
Dichloropropane, 1,3-
  Dichloropropene, cis-1,3-
  Dichloropropene, trans-1,3-
  Dichlorvos
  Dicrotophos (Bidrin)
  Dieldrin
  Diepoxybutane, 1,2:3,4-
  Diethyl ether
  Diethyl phtbalate
  Dimethoate
  Dimethoxybenzidine, 3,3'-
  Dimethyl phtnalate
  Dimethyl sulfone
  Dimethylaminoazobenzene, p-
 Dimethylbenz(a)anthracene, 7,12-
 Dimethylphenanthrene, 3,6-
 Dimethylphenol, 2,4-
 Dinitrobenzene,  1,4-
 Dinitrophenol, 2,4-
 Dmitrophenol, 2Tsec-butyl-4,6-
 (Dinoseb)
 Dinitrotoluene, 2,4-
 Dmitrotoluene, 2,6-
 Dioxane, 1,4-.
 Dioxathion
 Diphenyl ether
 Diphenylamine
 Diphenyldisulfide
 Diphenylhydrazuie, 1,2-
 Disulfoton
 Di-n-butyl phtnalate
 Di-n-octyl phthalate
 Di-n-propyhiitrosamme
 Docosane, n-
 Dodecane, n-
 Dysprosium
 Eicosane, n-
 Endosulfan sulfate
Endosulfan-I
Endosulfah-n
                                       3-5

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                                    EXHIBIT 3-1
          Pollutants Analyzed in the National Sewage Sludge Survey (cont'd.)
  Pollutant1
  Endnn
  Endrin aldehyde
  Endrin ketone
  Erbium
  Ether, 4-bromophenylphenyl
  Ether, 4-chlorophenylphenyl
  Ethion
  Ethyl cyanide                 '
  Ethyl methacrylate
  Ethyl methanesulfonate
  Ethylbenzene
  Ethylenethiourea
  Europium
  Famphur
  Fensulfothion
  Fenthion
  Fluoranthene
 'Fluorene
 Fluoride
 Gadolinium
 Gallium
 Germanium
 Gold
 Hafnium         ~  •            •>
 Heptachlor
 Heptachlor  epoxide
 Heptachlorodibenzofuran, 1,2,3,4,6,7,8-
 Heptachlorodibenzofuran, 1,2,3,4,7,8,9-
 Heptachlorodibenzo-p-dioxhi, 1,2,3,4,6,7,8-
 Hexachlorobenzene
 Hexachlorobutadiene
 Hexachlorocyclopentadiene
 Hexachlorodibenzofuran, 1,2,3,4,7,8-
 Hexachlorodibenzofuran, 1,2,3,6,7,8-
 Hexachlorodibenzofuran, 1,2,3,7,8,9-
 Hexachlorodibenzofuran, 2,3,4,6,7,8-
Hexachlorodibenzo-p-dioxin, 1,2,3,4,7,8-
Hexachlorodibenzo-p-dioxin, 1,2,3,6,'7,'s-
  PoUutant1
   lexachlorodibenzo-i
  Hexachloroethane
  Hexachlorbpropene
  Hexacosane, n-
  Hexadecane, n-
  Hexanoic acid
  Hexanone, 2-
  Holmium
  Indeno(l ,2,3-cd)pyrene
  Indium
  Iodine
  lodomethane
  Indium
  Iron
  Isobutyl alcohol
  Isodrin
  Isophorone
  Isopropylnaphthalene, 2-
  Isosafrole
 Lanthanum
 Lead
 Leptophos
 Lindane
 Lithium
 Longifolene
 Lutetium
 Magnesium
 Malachite green
 Malathion
 Manganese
 Mercury
 Mestranol
 Methapyrilene
 Methoxychlor
 Methyl methacrylate
 Methyl methanesulfonate
Methyl parathion
Methylbenzothioazole, 2-
lioxin,
                                      3-6

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                                   EXHIBIT 3-1
          Pollutants Analyzed in the National Sewage Sludge Survey (cont'd.)
  Pollutant1
  Pollutant1
  Methylcholanthrene, 3-
  Methylene chloride
  Methylene phenanthrene, 4,5-
  Methylene bis(2-chloroaniline), 4,4'-
  Methylfluorene, 1-
  Methyhiaphthalene, 2-
  Methylphenanthrene, 1-
  Methylphenol, 4-chloro-3-
  Mevinphos (Phosdrin)
  Mirex
  Molybdenum
  Monocrotophos
  N,N-dimethylfonnamide
  Naled (Dibrom)
 Naphthalene
 Naphthalenediamine, 1,5-
 Naphthoquinone, 1,4-
 Naphthoquinone, 2,3-dichloro-l,4-
 Naphthylamine, 1-
 Naphthylamine, beta-
 Neodymium
 Nickel
 Niobium
 Nitrate
 Nitrite
 Nitroaniline, 2,6-dichloro-4-
 Nitroanilhie, 2-
 Nittoaniluie, 3-
 Nitroaniline, 4-chloro-2-
 Nitroaniline, p-
 Nitrobenzene
 Nitrobenzene, l-chloro-3-
 Nittofen (TOK)
 Nitrophenol, 2-
 Nitrophenol, 4-
N-nitrosodiethylamine
N-nitrosodimethylamine
N-nitrosodiphenylamine
  N-nitrosodi-N-butylamine
  N-nitrosomethylethylamine
  N-nitrosomethylphenylamine
  N-nitrosomorpholine
I  N-nitrosopiperidine
I  Octachlorodibenzofuran
  Octachlorodibenzo-p-dioxin
  Octacosane, n-
  Octadecane, n-
  Osmium
  Palladium
  Parathion
  PCB-1016
  PCB-1221
  PCB-1232
 PCB-1242
 PCB-1248
 PCB-1254
 PCB-1260
 Pentachlorobenzene
 Pentachlorodibenzofuran,  1,2,3,7,8-
 Pentachlorodibenzofuran,  2,3,4,7,8-
 Pentachlorodibenzo-p-dioxin, 1,2,3,7,8-
 Pentachloroethane
 Pentachloronitrobenzene
Pentachlorophenol
Pentamethylbenzene
Pentanone, 4-methyl-2-
Perylene
Phenacetin
Phenanthrene
Phenol
Phenol, 2-methyl-4,6-dinitro-
Phenothiazine
Phenymaphthalene,  1-
Phenymaphthalene, 2-
Phorate
Phosmet
                                      3-7

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                                    EXHIBIT 3-1
          Pollutants Analyzed in the National Sewage Sludge Survey (cont'd.)
  Pollutant1
  Pollutant1
  Phosphamidon
  Phosphoric acid, trimethyl ester
  Phosphoric acid, tri-o-tolyl ester
  Phosphoric triamide, hexamethyl-
  Phosphorus
  Picoline, 2-
  Platinum
  Potassium
  Praseodymium
I  Pronamide
  Propane, 1,2-dibromq-3-chloro-
  Propanol, l,3-dichloro-2-
  Propanone, 2-
  Propenal, 2-
  Propenenitrile, 2-methyl-2-
  Propen-1-ol, 2-
  Propionic acid, 2-(2,4,5-trichlorophenoxy)
  (Silvex)
 Pyrene
 Pyridine
 Resorcindl
 Rhenium
 Rhodium               .
 Ruthenium
 Safrole
 Samarium
 Santox (EPN)
 Scandium
 Selenium
Silicon
Silver
Sodium
Squalene
Strontium
Styrene
Sulfiir
Tantalum
Tellurium
Terbium
  Terbufos                 ~
  Terpineol, alpha-
  Tetrachlorobenzene, 1,2,4,5-
  Tetrachlorodibenzofuran, 2,3,7,8-
  Tetrachlorodibenzo-p-dioxin, 2,3,7,8-
  Tetrachloroethane, 1,1,1,2-
  Tetrachloroethane, 1,1,2,2-
  Tetrachloroethene
  Tetrachloromethane
  Tetrachlorophenol, 2,3,4,6-
  Tetrachlorvniphos
  Tetracosane, n-
  Tetradecane, n-
  Tetraethyldithiopyrophosphate
  Tetraethylpyrophosphate
  Thallium
  Thianaphthene

 Thioacetamide
 Thioxanthe-9-one
 Thorium
 Thulium
 Tin
 Titanium
 Toluene
 Toluene, 2,4-diamino-
 Toluidine, 5-chloro-o-
 Toluidme, 5-nitro-o-
 Toluidine, o-
 Total heptachlorodibenzofurans
 Total heptachlorodibenzo-p-dioxms
 Total hexachlorodibenzofurans
 Total hexachlorodibenzo-p-dioxins
 Total kjeldahl nitrogen
 Total pentacMorodibenzoiurans
 Total pentachlorodibenzo-p-dioxins
 Total residue
 Total tetrachlorodibenzofurans
Total tetrachlorodibenzo-p-dioxms
                                      3-8

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                                     EXHIBIT 3-1
          Pollutants Analyzed in the National Sewage Sludge Survey (cont'd.)
   Pollutant1
   Ioxapnene
   Triacontane, n-
   Tribromomethane
   Trichlorobenzene, 1,2,3-
  •Trichlorobenzene, 1,2,4-
   Trichloroethane,  1,1,1-
   Trichloroethane,. 1,1,2-
   Trichloroethene
   Trichlorofluoromethane
   Trichlorofon
   Trichlorophenol,  2,3,6-
  Trichlorophenol,  2,4,5-
  Trichlorophenol,  2,4,6-
  Trichlorophenoxyacetic acid, 2,4,5-
  Trichloropropane, 1,2,3-
  Trifluralin (Treflan)
 Pollutant1
 inmetnoxybenzene, 1,2,3-
 Triphenylene
 Triprppyleneglycol methyl ether
 Trithiane,  1,3,5-
 Tungsten
 Uranium
 Vanadium
 Vinyl acetate
 Vinyl chloride
 Xylene, m-
 Xylene, o- and p-
 Ytterbium
Yttrium
Zuic
Zirconium
1 This exhibit presents-the 411 specific analytes in the NSSS. In 58 ^ 9269, it is stated that samples were analyzed
for a total of 412 analytes.  However, in Appendix C-List of NSSS Analytes in U.S. EPA, 1990a, there are 411
unique analytes out of 413 listed (crotoxyphos and phosphorus are listed twice).
                                        3-9

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  3.3        RESULTS OF PRELIMINARY HAZARD IDENTIFICATION STUDY

             The purpose of the Preliminary Hazard Identification study was to identify a list
  of Round Two pollutant candidates that would be further evaluated in the Comprehensive
  Hazard Identification study.   Pollutants analyzed in the NSSS formed the initial set of
  candidates for Round Two regulation. This section discusses the methods used to reduce the
  initial set of candidates to the list of Round Two pollutant candidates submitted to the Court
  in May, 1993. These methods included removing pollutants already regulated and pollutants
  with analytical problems; combining pollutant congeners into classes; removing pollutants
  based on  frequency  of detection data;  and ascertaining the availability of human  and
  ecological toxicity data.

  3.3.1     Pollutants Removed from Further Consideration

            Several NSSS pollutants were removed from further consideration for Round Two
  Total residue was deleted because it is the inert material left after all the pollutants have been
  extracted from sewage sludge.   Total kjeldahl nitrogen, the sum of the concentrations of
  ammonia (NH3) and organic nitrogen compounds in the trinegative oxidation state (N(-HI))
  was deleted because the concentrations of the individual compounds cannot be discerned and
  because  nitrogen is already controlled through management practices hi Part 503   The
  herbicide Dinoseb (2-sec-butyl-4,6-dinitrophenol)  could  not  be analyzed in the  NSSS
  Because  all U.S. uses of this herbicide have been cancelled, Dinoseb was eliminated from"
  further consideration under Round Two. Lastly, the ten individual pollutants regulated under
  Round One, shown in Exhibit 3-2, were not considered to be pollutant candidates for Round
  Two because they were already  regulated.  This does not preclude possible re-evaluation of
  the Round One pollutants hi the Round Two regulation,  however.

 3.3.2      Individual Pollutants Combined Into Classes

           Two   classes   of   pollutants,  polychlorinated   biphenyls  (PCBs)  and
 dioxms/dibenzofurans, were formed by aggregating individual pollutants (Exhibit 3-3) For
 PCBs,  seven  Aroclor  mixtures were combined  into  one category.  For  dioxins and
 dibenzofurans, 25 chlorinated dioxins and dibenzofurans were combined by multiplying each.
 congener's concentration by its corresponding toxicity equivalency factor (U.S. EPA  1989b)
 and adding the resultant values over all congeners for each POTW.

 3.3.3      Frequency of Detection of Pollutants

           The Agency removed from  further consideration  all  pollutants that had a
 frequency of detection of zero percent in sewage sludge sampled in the NSSS. A total of 254
 pollutants, shown in Exhibit 3-4, fell into that category.

           The remaining 114 pollutants hi the NSSS were then analyzed further   The
Agency used non-zero frequency of occurrence data to evaluate which of the remaining 114
pollutants should be candidates for Round  Two regulation. For each pollutant in the NSSS
except  dioxms/dibenzofurans, there was  only one frequency of occurrence value   For
dioxms/dibenzofurans, however,  frequency of occurrence was calculated in two ways: (1)

                                        3-10

-------
  dioxins/dibenzofurans were considered to be detected if at least  one of the individual
  congeners was detected above the minimum level; (2) dioxins/dibenzofurans were.considered
  to be detected if all of the individual congeners were  detected  above the minimum level.
  Because all of the individual congeners were not detected above the minimum level at any
  given POTW, the second method resulted in zero percent detection.  At the other extreme,
  the first method resulted in 100 percent detection.

        Of the 114 pollutants, the Agency deleted from further consideration those pollutants
  that were detected less than ten percent of the time if the results of a toxicity analysis (see
  Appendix A) indicated  that a pollutant did  not have the potential to affect public health
  adversely.  EPA concluded that if a pollutant was not present in more than ten percent of the
  sewage sludge samples and is not highly toxic, the potential to adversely affect public health
  and the environment is low. Of the 69 pollutants deleted for this  reason, 35 had a frequency
  of detection of two percent or less; 22 had a frequency of detection greater than two percent,
  but equal to or less than five percent; and 12 had a frequency of detection greater than five
 percent, but less than ten percent.  After deleting those 69 pollutants, 45 pollutants remained
 as candidates for the Round Two regulation,  as shown in Exhibit 3-6.

 3.3.4  Available Human Health and Ecological Toxicity Data

        For the 45 candidate pollutants that had frequencies of occurrence of ten percent or
 greater, EPA obtained available human and ecological toxicity data. For human toxicity data,
 EPA predominantly relied on IRIS (Integrated Risk Information System) and HEAST (Health
 Effects Assessment Summary  Tables).  EPA also attempted to obtain human toxicity data
 from the following sources in descending order of preference:

              Reportable Quantities/Potency Factors,
              California Environmental Protection Agency data,
              HSDB (Hazardous Substances Data Base),
              RTECS (Registry of Toxic Effects of Chemical Substances), and
              Office of Pesticide Programs data sources.

       For carcinogenic effects, EPA obtained both the slope potency factor, qr*, hi units of
 (mg/kg-day)'1 for the oral and inhalation pathways, and the weight of evidence factors as
 classified by the Cancer Risk Assessment Guidelines (U.S. EPA, 1986b).   For non-
 carcinogenic effects, the Risk  Reference Doses (RfDs)  for the oral pathway and the Risk
 Reference Concentrations (RfCs)  for the inhalation pathway, in  units of (mg/kg-day) and
 (mg/m3), respectively, were obtained.   RfCs were converted to units of (mg/kg-day) by
 assuming a person weighs 70 kg and breathes 20m3 of air per day. For those chemicals with
 only noncarcinogenic effects, it was also noted whether any positive mutagenicity studies had
 been reported. These human health toxicity data are shown hi Exhibit 3-7.

        EPA's Health and Ecological Criteria Division provided several sources of ecological
toxicity data.  These sources included  work hi support  of the Great Lakes Water Quality
Initiative (U.S. EPA, 1993b), "Implementation of a Chemical Ranking System" (U.S. EPA,
 1990b), Oneliner in PIRANHA (U.S. EPA, 1991b), "Screening Study for Wildlife Criteria
Development" (U.S. EPA,  1989f), Devillers and Exbrayat (1992), Harfenist et al. (1989),

                                        3-11

-------
  and 40 CFR Part 131 (Federal Register, Part H, December 22, 1992).  These ecological
  toxicity data are shown in Exhibit 3-8.                                  .

        For 14 pollutants, shown in Exhibit 3-9, no human or ecological toxicity data were
  available; these pollutants were not considered further.  In addition, there were no human
  toxicity data from IRIS or HEAST for the pollutant n-decane; the only available data were
  from the least preferable source.  Therefore n-decane also was not  considered further.
  Although human or ecological toxicity data were riot available for aluminum, some evidence
  exists  that aluminum  may  be a phytotoxin.   Florida farmers have  reported that high
  background concentrations  and high loadings of aluminum  have led to phytotoxicity and
  decreased crop yields.  Therefore, aluminum was kept and evaluated in the Comprehensive
  Hazard Identification study.

 3.3.5  Pollutant Candidate List  for Round Two Regulation

        Of the  remaining 30 pollutants, seven pollutants were evaluated for some use or
 disposal practices under Round One; they are being re-evaluated in Round Two because they
 were not evaluated for all use or disposal practices (Exhibit 3-10).  Beryllium was initially
 modeled only under the incineration pathway for the Round One risk assessment due to a lack
 of data; it is considered as a pollutant candidate for Round Two for the land application and
 surface disposal pathways.   Bis(2-ethylhexyl)phthalate was not modeled under the  land
 application pathways hi Round One due to a lack of data, and therefore is considered as a
 pollutant candidate in Round Two.  Although the PCB Aroclor mixtures were evaluated for
 Round  One, coplanar congeners of PCBs were not evaluated; coplanar PCBs are pollutant
 candidates for Round Two because they have characteristics similar to those of dioxins. Four
 compounds considered  hi the Environmental Profiles  ranking system (discussed in Section
 2.3.2),  cyanide, fluoride, methylene chloride, and phenol, are considered again hi Round
 Two, because previously they were not fully evaluated for all use or disposal practices. -

       Even though it is  not known if asbestos is present hi sewage sludge,  asbestos was
 raised as a possible pollutant candidate after the public comment period for the Round One
 rule-was  closed.   NSSS  sewage sludge samples were  not  analyzed for asbestos; friable
 asbestos, however, is reported as  being released under the  Toxics Release Inventory.   If
 asbestos were present hi sewage sludge, it could potentially be released and become airborne
 as the sewage sludge matrix breaks down. It could then undergo secondary deposition on soil
 and water, as well  as on food and feed crops. The secondary deposition pathway was never
evaluated during Round One.  After including asbestos as a potential candidate, a total of 31
pollutant candidates resulted, as  shown hi  Exhibit 3-11..   Exhibit 3-12 summarizes the
rationale for the number of pollutants selected as candidate pollutants for the Round Two
sewage sludge regulation.
                                        3-12

-------
                                       EXHIBIT 3-2
             Pollutants Regulated in Round One Sewage Sludge Regulation
                               Pollutant
                               Arsenic
                               Beryllium1
                               Cadmium
                               Chromium
                               Copper
                               Lead
                               Mercury1   •
                               Molybdenum
                               Nickel
                               Selenium
                               Zinc
                               Total Hydrocarbons2
1 Regulated for incineration through a National Emission Standard, which is referenced in Part 503.

2 Note that "Total Hydrocarbons" is not a pollutant explicitly listed in the 411 analytes in  the NSSS.  Total
Hydrocarbons encompass all organic compounds in the stack gas exiting an incinerator.
                                          3-13

-------
                              EXHIBIT 3-3
 Pollutants Combined Into Classes or Removed from Further Consideration
Number of Pollutants
       Deleted
                 Explanation
         24
 7 Aroclor mixtures combined into one composite
 called "PCBs".

 25 chlorinated dioxins and furans combined using
 Toxic Equivalency  Factors into one  surrogate
 called "dioxins".

 Total   residue  was  removed  from   further
 consideration because it is not a pollutant; it is the
 inert material left after all the pollutants have been
 extracted from sewage sludge.

 Total  Kjeldahl   Nitrogen,  the  sum  of  the
 concentrations of  ammonia (NH3)  and organic
 nitrogen compounds hi the trinegative oxidation
 state (N(-H[)),   was  removed  from  further
 consideration because the concentrations  of the
 individual compounds  cannot be discerned and
 because   nitrogen   is   controlled   through
 management practices hi Part 503.

 Dinitrophenol,   2-sec-butyM,6-  (also  called
 Dinoseb) was  dropped from the NSSS due  to
 analytical problems.
        33
Total number  of pollutants from the  NSSS
analytical   survey   removed   from   further
consideration.
                                3-14

-------
                                  .EXHIBIT 3-4
  Pollutants With a Frequency of Detection of Zero Percent in the National Sewage
                                  Sludge Survey
 Pollutant
 Acenapntnene
 Acenaphthylene
 Acrylonitrile
 Aminobiphenyl, 4-
 Aniline
 Aniline, 2,4,5-trimethyl-
 Anisidine, o-
 Aramite
 Azinphos ethyl
 Benzanthrone
 Benzene
 Benzenethiol
 Benzidine
 Benzo(ghi)perylene
 Benzofluorene, 2,3-
 Benzonitrile, 3,5-dibromo-4-hydroxy-
 Benzoquinone, 2,6-di-tert-butyl-p-
 Benzothiazole, 2-(methylthio)
 Biphenyl, 4-nitro
 Bis(2-chloroethoxy) methane
 Bis(2-chloroethyl) ether
 Bis(2-chloroisopropyl) ether
 Bismuth
 Bromodichloromethane
 Bromomethane
 Butadiene,  2-chloro-l,3-
 Butene, trans-l,4-dichloro-2-
 Captafol
 Captan
 Carbazole
 Carbophenothion (Trithion)
 Cerium
Chlordane
Cfiloroacetdnitrile
Chlorobenzene, l-bromo-2-
Chlorobenzene, l-bromo-3-
 Pollutant
 unioroetnane
 Chloroethylvinyl ether, 2-
 Chlorofenvinphos
 Chloromethane
 Chlorophenol, 2-
 Chloropropene, 3-
 Ciodrin
 Coumaphos
 Crotonaldehyde
 Grotoxyphos
 DDD
 Demeton
 Di-n-propyMtrosamine
 Diallate
 Dibenz(a,h)anthracene
 Dibenzothiophene
 Dibromochloromethane
 Dibromoethane, 1,2-
 Dibromomethane
 Dichloroaniline, 2,3-
 Dichlorobenzene, 1,2-
 Dichlorobenzene, 1,3-
 Dichlorobenzidme, 3,3'-
 Dichloroethane, 1,1-
 Dichloroethane, 1,2,-
 Dichloroethene, 1,1-
 Dichloronitrobenzene, 2,3-
 Dichlorophenol, 2,4-
 Dichlorophenol, 2,6-
 Dichloropropane, 1,2-
 Dichloropropane, 1,3-
 Dichloropropene, cis-1,3-
Dichloropropene, trans-1,3-
Dichlorvos
Dicrotophos (Bidrin)
Diethyl ether
                                     3-15

-------
                                  EXHIBIT 3-4
          Pollutants With a Frequency of Detection of Zero Percent in the
                     National Sewage Sludge Survey (cont'd.)
  Pollutant
  Diethyl phthalate           ~~
  Dimethoxybenzidine, 3,3'-
  Dimethyl sulfone
  Dimethylaminoazobenzene, p-
  Dimethylbenz(a)anthracene, 7,12-
  Dimethylphenanthrene, 3,6-
  Dimethylphenol, 2,4-
  Dinitrobenzene, 1,4-
  Dinitrophenol, 2,4-
  Dinitrotoluene, 2,4-
  Dinitrotoluene, 2,6-
 Dioxathion
 Diphenyl ether
 Diphenylamine
 Diphenyldisulfide
 Diphenyihydrazine, l,2r
 Disulfoton
 Dysprosium
 Endosulfan sulfate
 Endrin aldehyde
 Endrin ketone
 Erbium
 Ether, 4-bromophenylphenyl
 Ether, 4-chlorophenylphenyl
 Ethion
 Ethyl cyanide
 Ethyl methacrylate
 Ethyl methanesulfonate
 Ethylenethiourea
 Europium
 Famphur
 Fensulfothion
 Fenthion
Fhiorene
Gadolmium
Gallium
Germanium
 Pollutant
 Gold                ^	—
 Hafnium
 Heptachlor
 Hexacnlorobenzene
 Hexachlorobutadiene
 Hexachlorocyclopentadiene
 Hexachloroethane
 Hexachloropropehe
 Hohnium
 Indeno(l ,2,3-cd)pyrene
 Indium
 Iodine
 lodomethane
 Indium
 Isodrin
 Isophorone
 Isopropyuiaphthalene, 2-
 Isosafrole
 Lanthanum
 Leptophos
 Lindane
 Lithium
 Longifolene
 Lutetium
 Malachite green
 Malathion
 Mestranol
 Methapyrilene
 Methoxychlor
 Methyl methacrylate
 Methyl methanesulfonate
 Methyl parathion
 Methylbenzothioazole, 2-
 Methylcholanthrene, 3-
 Methylene bis(2-chloroaniluie), 4,4'-
 Methylene phenanthrene, 4,5-
Methylfluorene,  1-
                                     3-16

-------
                                   EXHIBIT 3-4
          Pollutants With a Frequency of Detection of Zero Percent in the
                     National Sewage Sludge Survey (cont'd.)
  Pollutant
  Pollutant
  iviernyipnenanrnreryft(  i-
  Methylphenol, 4-chloro-3-
  Mevinphos (Phosdrin)
  Mirex
  Monocrotophos
  N-nitrosodi-n-butylamine
  N-nitrosodiethylamine
  N-nitrosodimethylamine
  N-nitrosomethylethylamine
  N-nitrosomethylphenylamine
  N-nitrosopiperidine
  N-nitrosomorpholine
  Naphthalenediamine, 1,5-
  Naphthoquinone, 1,4-
  Naphthoquinone, 2,3-dichloro-l,4-
 Naphthylamine, 1- .
 Naphthylamine, beta-
 Neodymium
 Niobium
 Nitroaniline, 2-
 Nitroaniline, 2,6-dichloro-4-
 Nitroaniline, 3-
 Nitroaniline, 4-chloro-2-
 Nitroaniline, p-
 Nitrobenzene
 Nitrobenzene, l-chloro-3-
 Nitrophenol, 2-
 Nitrophenol, 4-
 N,N-dimethylfonnamide
 Osmium
 Palladium
 Parathion
 Pentachlorobenzene
 Pentachloroethane
 Pentachlorophenol
Pentamethylbenzene
Perylene
  Fnenacetin
  Phenol, 2-methyl-4,6-dmitro-
  Phenothiazine
  Phenylnaphthalene, 1-
  Phenyhiaphthalene, 2-
  Phorate
  Phosmet
  Phosphoric acid, trimethyl ester
  Phosphoric triamide, hexamethyl-
  Phosphorus
  Platinum
  Potassium
 Praseodymium
 Pronamide
 Propane, l,2-dibromo-3-chloro-
 Propanol,  l,3-dichloro-2-
 Propen-1-ol, 2-
 Propenal, 2-
 Propenenitrile, 2-methyl-2-
 Pyridhie
 Resorcinol
 Rhenium
 Rhodium
 Ruthenium
 Safrole
 Samarium
 Scandium
 Silicon
 Squalene
 Strontium
 Sulfur
 Tantalum
 Tellurium
 Terbium
Terbufos
Tetrachlorobenzene, 1,2,4,5-
Tetrachloroethane, 1,1,1,2-
                                     3-17

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                                  EXHIBIT 3-4
         Pollutants With a Frequency of Detection of Zero Percent in the
                     National Sewage Sludge Survey (cont'd.)
 Pollutant
 Tetrachloroethane,  1,1,2,2T
 Tetrachlorophenol,  2,3,4,6-
 Tetrachlorvinphos
 Tetraethyldithiopyrophosphate
 Thianaphthene
 Thioacetamide
 Thioxandie-9-one
 Thorium
 Thulium
 Toluene, 2,4-diamino-
 Toluidine, 5-chloro-o-
 Toluidine, 5-nitro-o-
 Toluidine, o-
 Toxaphene
 Tribromomethane
 Trichlorobenzene, 1,2,3-
Trichlorobenzene, 1,2,4-
 PoUutant
  richloroethane, 1,1,1-
 Trichloroethane, 1,1,2-
 Trichlorofon
 Trichlorophenol, 2,3,6-
 Trichlorophenol, 2,4,5-
 Trichlorophenol, 2,4,6-
 Trichloropropane,  1,2,3-
 Trimethoxybenzene,  1,2,3-
 Triphenylene
 Tripropyleneglycol methyl ether
 Trithiane, 1,3,5-
 Tungsten
 Uranium
 Vinyl acetate
 Vinyl chloride
Ytterbium
Zirconium
                                    3-18

-------
                                 EXHIBIT 3-5
Pollutants With A Frequency of Detection of Less Than Ten Percent in the National
                             Sewage Sludge Survey
      Pollutant
Frequency of Detection (%)
      Acetophenone
      Aldrin
      Anthracene
      Azinphos methyl
      Benz(a)anthracene
      Benzo(a)pyrene
      Benzo(b)fluoranthene
      Benzo(k)fluoranthene
      Benzole acid
      Benzyl alcohol
      BHC, alpha-
      BHC, beta-
      BHC, delta-
      Biphenyl
      Butyl benzyl phthalate
      Chloroaniline, p-
      Chlorobenzene
      Chlorobenzilate
      Chloroform
      Chloronaphthalene, 2-
     Chlorpyrifos
     Chrysene
     Cobalt
     Cresol, o-
     Cymene,  p-
     DDE
     DDT
     Di-n-butyl phthalate
     Di-n-octyl phthalate
     Diazinon
     Dibenzofuran
     Dichlorobenzene, 1,4-
     Dichloroethene, trans-1,2-
     Dieldrin
     Diepoxybutane, 1,2:3,4-
              2
              3
              2
              2
              4
              3
              7
              5
              6
              1
              2
              6
              2
              1
              9
              5
              2
              7
              1
              1
              3
              5
              9
              6
              7
              1
              2
              5
              1
              2
              1
              2
              1
              5
              2
                                    3-19

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                              EXHIBIT 3-5
    Pollutants With A Frequency of Detection of Less Than Ten Percent
              in the National Sewage Sludge Survey (cont'd.)
   Pollutant
                                                Frequency of Detection (%)
   Dimethoate
   Dimethyl phthalate
   Dioxane, 1,4-
 " Docosane, n-
   Endosulfan-I
   Endrin
   Ethylbenzene
   Fluoranthene
   Heptachlor epoxide
  Hexanone, 2-
  Isobutyl alcohol
  Methylnaphthalene, 2-
  N-nitrosodiphenylamine
  Naled (Dibrom)
  Naphthalene
  Nitrofen (TOK)
  Octadecane, n-
 Pentanone, 4-methyl-2-
 Phenanthrene
 Phosphamidon
 Phosphoric acid, tri-o-tolyl ester
 Picolhie, 2-
 Pyrene
 Santox (EPN)
 Styrene
 Terpineol, alpha-
 Tetrachloroethene
 Tetrachloromethane
 Tetraethylpyrophosphate
 Trichloroethene
 Trichlorofiuoromethane
 Trifluralhi (Treflan)
. Xylene, m-
 Xylene, o- and p-
                                3-20

-------
                                 EXHIBIT 3-6
Pollutants With A Frequency of Detection of Ten Percent or Greater in the National
                             Sewage Sludge Survey
     Pollutant
Frequency of Detection (%)
    Acetic acid (2,4-dichlorophenoxy)
    Aluminum '
    Antimony
    Barium
    Beryllium
    Bis(2-ethylhexyl)phthalate
    Boron
    Butanone, 2-
    Calcium
    Carbon disulfide
    Crespl, p-
    Cyanides (Soluble salts and complexes)
    Decane, n-
    Dioxins
    Dodecane, ri-
    Eicosane, n-  •
    Endosulfan-n
    Fluoride
    Hexacosane, n-
    Hexadecane, n-
    Hexanoic acid
    Iron
    Magnesium
    Manganese
    Methylene chloride
    Nitrate
    Nitrite
    Octacosane, n-
    PCBs
    Pentachloronitrobenzene
   Phenol
   Propanone, 2-
   Propionic acid, 2-(2,4,5-trichlorophenoxy)
   Silver
   Sodium.
   Tetracosane, n-
   Tetradecane, n-
               16
              100
               38
              100
               22
               62
               48
               34
              100
               10
               43
               37
               10
              100
               14
               13
               12
               63
               15
               12
              40
              100
              100
              100
              42
              95
              83
              13
              19
              10
              34
              58
              15
              84
             100
              15
              14
                                    3-21

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                             EXHIBIT 3-6
Pollutants With A Frequency of Detection of Ten Percent or Greater in the
                National Sewage Sludge Survey (cont'd.)
Pollutant
Frequency of Detection (%)
Thallium
Tin
Titanium
Toluene
Triacontane, n-                 s
Trichlorophenoxyacetic acid, 2,4,5-
Vanadium
Yttrium
               15
               84
               98
               61
               14
               29
               62
               61
                               3-22

-------
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                              3-26

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                                 EXHIBIT 3-9
    Pollutants With No Human Health or Ecological Toxicity Data Available
                         Pollutant
                         Calcium
                         Decane, n-1
                         Dodecane, n-
                         Eicosane, n-
                         Hexacosane, n-
                         Hexadecane, n-
                         Hexanoic acid
                         Iron
                         Magnesium
                         Octacosane, n-
                         Sodium
                         Tetracosane, n-
                         Tetradecane, n-
                         Triacontane, n-
                         Yttrium
1 Available data from the Office of Pesticide Programs RfD Tracking Report (27 January 1992) were not
considered to be appropriate for the assessment of the Round Two list of pollutants.
                                   3-27

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                                 EXHIBIT 3-10
      Round One Pollutants Included as Potential Candidates For Round Two
        Pollutant
                      Rationale
 PCBs
 Beryllium


 Phenol.


 Methylene chloride


 Bis(2-ethylhexyl)phthalate


Cyanide


Fluoride
 Aroclor mixtures of PCBs were evaluated in Round One.
 Coplanar PCBs are being  considered for  Round Two
 because of their chemical and lexicological similarities to
 dioxins.
 Not evaluated for all exposure pathways
 practices in Round One.

 Not evaluated for all exposure pathways
 practices in Round One.

 Not evaluated for all exposure pathways
 practices in Round One.

 Not evaluated for all exposure pathways
 practices in Round One.

 Not evaluated for all exposure pathways
practices in Round One.

Not evaluated for all exposure pathways
practices hi Round One.
and use/disposal


and use/disposal


and use/disposal


and use/disposal


and use/disposal


and use/disposal
                                    3-28

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                                      EXHIBIT 3-11
                   31 Pollutant Candidates For Round Two Regulation1
                        Pollutant
                        Acetic acid (2,4-dichiorophenoxy)
                        Aluminum2
                        Antimony
                        Asbestos3
                        Barium
                        Beryllium
                        Bis(2-emylhexyl)phthalate  -
                        Boron
                        Butanone,  2-
                        Carbon disulfide
                        Cresol, p-
                       Cyanides (soluble salts and complexes)
                       Dioxins and dibenzofurans
                       Endosulfan-E
                       Fluoride
                       Manganese
                       Methylene chloride
                       Nitrate  -
                       Nitrite
                       Pentachloronitrobenzene
                       Phenol   .
                       Polychlorinated biphenyls - coplanar
                       Propanone, 2-
                       Propionic acid, 2-(2,4,5-trichlorophenoxy)
                       Silver
                       Thallium
                       Tin
                       Titanium
                       Toluene
                       Trichlorophenoxyacetic acid, 2,4,5-
                       Vanadium
' Pollutants detected at a frequency of at least ten percent with human health and/or ecological toxicity data available
 Aluminum does not have human health or ecological toxicity data available, but is included due to its potential for
phytotoxicity.
3 Asbestos was not tested in the NSSS, but is toxic, persistent, and may be in sewage sludge.
                                          3-29

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                                 EXHIBIT 3-12
Rationale for the Number of Pollutants Selected as Candidates for the Round Two
                            Sewage Sludge Regulation
Rationale
Number of
Pollutants
     Pollutants for which NSSS sewage sludge samples
     were analyzed (Exhibit 3-1).

     Pollutants regulated in the Round One sewage
     sludge regulation (Exhibit 3-2).

     Pollutants combined into classes of congeners or
     removed from further consideration (Exhibit 3-3).

     Pollutants with a frequency of detection of zero
     percent (Exhibit 3-4).

     Pollutants deleted because tfiey did not have a non-
     zero frequency of detection of ten percent or
     greater (Exhibit 3-5). ^

     Pollutants detected at a frequency of ten percent or
     greater (Exhibit 3-6).

     Pollutants detected at a frequency of ten percent or
     greater, but with insufficient human health or
     ecological toxicity data available (Exhibit 3-9).

    Pollutants detected at a frequency of ten percent or
    greater, with human health and/or ecological
    toxicity data available.

    Asbestos added.

    Number of candidate pollutants for Round Two
    sewage sludge  regulation  (Exhibit 3-11).
 411


 10


 33


 254  .


 69



 45


 15



 30



 1

31
                                    3-30

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             4.  FINAL LIST OF ROUND TWO POLLUTANTS

         This  section presents the methods and the results of the Comprehensive Hazard
  Identification study, in which a quantitative risk assessment for the Highly  Exposed
  Individual,   including   dose-response  evaluation,   exposure  assessment,   and   risk
  characterization, is performed.  The 31 pollutant candidates for the Round Two sewage
  sludge  regulation, identified in the Preliminary Hazard'Identification, are evaluated in this
  Comprehensive  Hazard Identification.  Note that in the Technical Support Documents for
  Round  One, the calculations begin with an acceptable level of risk, and work backwards to
  determine  what pollutant  concentrations in the sewage sludge are acceptable  for that
  use/disposal practice, thereby calculating pollutant limits.  In this study, levels of risk that
  might be associated with a given pollutant under a given use/disposal practice are estimated
  based on sewage sludge pollutant concentrations from the NSSS.  Those pollutants/practices
  with high risk estimates are candidates for the final list of Round Two pollutants.  The results
  of this Comprehensive Hazard Identification indicate that  only a subset of the 31 pollutants
  should be considered for regulation in Round .Two.

  4.1    GENERAL   APPROACH   FOR   THE   COMPREHENSIVE  HAZARD
        IDENTIFICATION                                                ™^AKU

        The purpose of the Comprehensive Hazard Identification study is to identify pollutants
 that warrant further consideration for the  final list of Round Two pollutants.  Analyses are
 performed to identify pollutants that may potentially cause human health or ecological risk
 for a Highly Exposed Individual (HEI).  Consistent with the EPA Guidelines for Exposure
 Assessment (57  FR  22888, May 29,  1992), the risk to the HEI is estimated  using  a
 combination of high-end and average assumptions designed to give a plausible estimate of the
 individual risk at the upper end of the risk distribution (e.g., above the 90th percentile of the
 actual distribution).

       In general for mis study, high-end assumptions are used to characterize sewage sludge
 concentrations and certain exposure parameters,  while average values are typically used to
 characterize use/disposal practices and soil and meteorological characteristics.  Specifically
 sewage sludge concentrations are based on the 95th percentile concentrations of pollutants
 obtained in the NSSS, with non-detects set equal to the minimum level (e.g., the minimum
 concentration of pollutant that could be measured) (see Exhibit 4-1).  For each sewage sludge
 use/disposal practice, the HEI is defined  as  "an individual who remains for an extended
 period of time at or adjacent to the site where the maximum exposure occurs" (U.S. EPA,
 1992a).  Numerous exposure assumptions are specific to each exposure pathway and are given
 in the subsequent sections.1

       This  chapter describes the methods used for each sewage sludge use or  disposal
practice and exposure pathway (Section 4.2 (land application), 4.3 (surface disposal), and 4 4
(incineration)).  Next, methods for estimating human health and ecological risk are presented
   More detailed explanations for the derivations of the specific values used in this study are provided in the
Technical Support Documents for Round One (e.g., U.S. EPA, 1992a).
                                        4-1

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(Section 4.5). For those pollutant-exposure pathway combinations for which an exposure can
be estimated, the calculated risk associated with that exposure is then presented. Based on
these risk estimates, the pollutants that warrant further consideration for inclusion on the final
list of Round Two pollutants are presented in Chapter 5.
                                        4-2

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                                 EXHIBIT 4-1

       95th Percentile Concentrations for Round Two Candidate Pollutants
                 Pollutant
  95th Percentile Sewage Sludge

Concentrations1 (mg/kg dry weight)
  Acetic acid (2,4-dichlorophenoxy)
              0.030
  Aluminum
                                                        36,400
  Antimony
               24
 Asbestos2
                                                     Not Available
 Barium
                                                         1,730
 Beryllium
                8
 Bis(2-ethylhexyl)phthalate
               191
 Boron
                                                          182
 Butanone, 2-
              69.3
 Carbon disulfide
                                                         3.13
 Cresol,
                                                         306
 Cyanides (soluble salts and complexes)
               130
 Dfoxins and dibenzofurans
                                                      3.11 x
 Endosulfan-n
                                                        0.0667
 Fluoride
                                                         411
 Manganese
                                                        1,620
Methylene cWoride
              31.3
Nitrate
                                                        5,020
Nitrite
                                                         462
Pentachloronitrobenzene
                                                       0.0793
Phenol
Polychlorinated biphenyls — coplanar3

Propanone, 2-
Propionic acid, 2-(2,4,5-trichlorophenoxy)

Silver
                                                        57.5
              5.4
              116
             I^^^BH^^HK


             0.040
                                                         128
                                    4-3

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Pollutant
Thallium
Tin
Titanium
Toluene
Trichlorophenoxyacetic acid. 2,4,5-
Vanadium
95th Percentile Sewage Sludge .
Concentrations1 (mg/kg dry weight)
10.6
138
363
238
0.0505 ,
64.1
  1 Non-deiccts set equal to the Minimum Level. Concentrations from the NSSS.
  * Asbestos was not tested in the NSSS, but is toxic, persistent, and may be in sewage sludge.
  3 Sewage sludge samples were not analyzed for coplanar PCBs in the NSSS. A composite PCB concentration was
  estimated by combining the concentrations of the seven Aroclor mixtures measured in the NSSS.


 4.2    LAND APPLICATION PATHWAY EXPOSURE METHODOLOGIES

        Methods were developed in Round One to evaluate risk from sewage sludge that is land-
 applied to agricultural and non-agricultural sites.  These methods include evaluating both
 human health and ecological risks associated with exposure  to sewage sludge through 14
 different pathways. In Round Two, an additional exposure pathway, breastfeeding, is  also
 considered.  These 15 exposure pathways and the corresponding HEIs are summarized hi
 Exhibit 4-2."

        To estimate exposure to pollutants in sewage sludge that is land-applied, several non-pollutant-
 specific types of data are required, including information on application practices and  soil
 characteristics.  The average values used for these parameters are shown in Exhibit 4-3. The
 way hi which these data were combined with pollutant-specific data to estimate exposure is
 described in Sections 4.2.1 through 4.2.15.    "

       For both agricultural and non-agricultural land application sites, it is necessary to
 estimate the number of years that a site is used and the rate at which sewage sludge is applied
 to that site. An estimate of the depth to which sewage sludge is incorporated at the site also
 must be made.  The values used for these parameters in this analysis are presented in Exhibit
 4-3.  Note that for the forest.and public contact sites, depth of incorporation is assumed to
 be zero, and therefore the "soil concentration" of a pollutant is the same as the sewage sludge
 concentration.

       For the soil at agricultural land and reclaimed  sites, an average bulk density of 1600
kg/m3 is assumed (U.S. EPA,  1992a).  For the bulk density of sewage sludge-amended soil
an average value of 1400 kg/m3 is assumed (U.S. EPA, 1992a). For natural "background"
soil  concentrations  of inorganics, 90th  percentile  concentrations of  inorganics  in soil
throughout the United States  were used  (U.S.  Geological Survey,  1992).   To ascertain
                                         4r4

-------
 whether sewage sludge pollutant concentrations were greater than natural soil concentrations
 the  90th percentile soil  concentrations were  compared to  the 95th percentile pollutant
 concentrations in sewage sludge.  As shown in Exhibit 4-4, for three inorganics the 95th
 percentile  sewage sludge  concentrations  are less than  (aluminum and titanium)  or
 approximately equal to (vanadium)  the 90th percentile natural soil concentrations   This
 suggests that natural concentrations of these inorganics contribute significantly to the overall
 exposure of an HEI.  For antimony and tin, sewage sludge concentrations are much greater
 than  natural soil  concentrations,  indicating that  sewage  sludge  loadings  are the  major
 determinant of an HEI's exposure to those inorganic pollutants. In this analysis, background
 concentrations of nitrate and nitrite are  not applicable due to the cycling of nitrogen in soil
 systems. The background concentration of asbestos also is not applicable because asbestos
 would not be taken up by crops.  Cyanide was. the only applicable inorganic pollutant for
 which background soil concentration data were not available.  For the organic pollutants
background  concentration data are not required because it is assumed that there are not
natural concentrations of organic pollutants in soil.
                                       4-5

-------
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                                4-8

-------
                                           EXHIBIT 4-3
              Average Values for Sewage Sludge Land Application
                                                       Parameters
      Parameter
                Definition
                                                                  Value
                                                                  Notes
   N, agricultural
   land
  Number of years of application to
  agricultural land
   20
 assumed applied
 once even' year for
 20 year site life
 (U.S...EPA, 1993a)
   N, forest
  Number of years of application to forest
  land
                                                                              assumed applied
                                                                              once every three
                                                                              years for 20 year
                                                                              site life (U.S. EPA,
                                                                              1984)
   N, reclamation
   sites
 Number of years of application to
 reclamation sites
   1
 assumed one-time
 application
    ,  public contact
 Number of years of application to public
                     contact sues
  10.        assumed applied
             once every two
             years for 20 year
             site life (U.S. EPA,
             1984)
  NJW, agricultural
  land, forest,
  public contact
 Site life, i.e., period of time during
 which sewage sludge may be applied
 20yr
    3OT, reclamation
  site
 Site life, i.e., period of time during
 which sewage sludge may be applied
  lyr
  d, agricultural
  land
 Depth of incorporation on agricultural
 land
15 cm
U.S. EPA, 1992a
  d, forest
Depth of incorporation on forest land
                                                                 Ocm
                                                                             no incorporation
                                                                             assumed
  d, reclamation
  sites
Depth of incorporation on reclamation
sites
10cm
U.S. EPA,  1984
  d, public contact
Depth of incorporation on public contact
sites
                                                                 Ocm
                                                                             no incorporation
                                                                             assumed
 AR, agricultural
 land
Annual whole sludge application rate for
agricultural land
            U.S.. EPA; 1992a
                                                             dry Mg/ha-yr
                    Annual whole sludge application rate for
                    forest land
                                              26
                                         dry Mg/ha-yr1
            U.S. EPA, 1992a
 AR, reclamation     Annual whole sludge application rate for
                                              74
                                         dry Mg/ha-yr1
            U.S. EPA, 1992a
                   reclamation sites
                   Annual whole sludge application rate for
                   public contact sites
                                              18
                                         dry Mg/ha-yr'
            U.S. EPA, 1992a
                   Bulk density of soil at agricultural land
                   and reclamation sites
                                                         U.S. EPA/ 1992a
                   Bulk density of sewage sludge-amended
                   soil
                                                         U.S. EPA, 1992a
Note that 1 Mg = 1 megagram = 1 metric ton = 1000 kg.
                                              4-9

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                                       EXHIBIT 4-4
                     Background Concentrations of Pollutants in Soil
Pollutant
Aluminum

Antimony
Barium
Beryllium
Boron
Cyanide (soluble salts and
complexes)
Fluoride
Manganese
Silver
Thallium
Tin
Titanium
Vanadium
90th Percentile
Background
Concentration in Soil1
(mg/kg dry weight)
68,000
0.51
452
0.65
27
NA
220
342
O2
O3
0.94
3400
60
Ratio of Sewage Sludge
(95th) to Soil
Concentrations
(dimensionless)
. , 0.54
47
3.8
12
6.7
NA
1.9
4.7
NA
NA
150
0.11
1.1
NA means Not Available.
1 Concentration obtained by calculating 90th percentile value, based on geometric means and standard deviations
obtained from  U.S. Geological Survey, 1992.
2 Silver was measured too infrequently for a reliable mean concentration to be calculated, as discussed in U S
Geological Survey, 1992.
  Thallium was analyzed for in all samples but was never found, as discussed in U.S. Geological Survey, 1992.
4.2.1. Pathway 1 - Ingestion of Crops Grown on Sewage Sludge-Amended Soil

       Pathway 1  evaluates human ingestion of plants that have taken up pollutants from
sewage sludge-amended agricultural and non-agricultural  lands.   Non-agricultural, lands
include forests, reclaimed land,  and public contact sites.
                                          4-10

-------
 Mass Balance Equations

       to be conservative in these analyses, the entire mass of a pollutant applied hi sewage
 sludge over the life of a land application site is assumed to be available for plant uptake.
 Unlike Pathway  1  in  the Technical Support Document for Land Application of Sewage
 Sludge, developed for  the Round One regulation (U.S. EPA, 1992a), this analysis does not
 assume that organic pollutants either degrade or volatilize each year between sewage sludge
 applications.  This conservative approach is used for this level of assessment because: (a)
plant uptake of most pollutants is low and (b) the dissipation of many of the pollutants being
considered in Round Two is slow. If this pathway yielded high risk for a particular pollutant
the assumptions would  be refined.

      In  calculating total pollutant concentration hi the soil (CZ}) for the agricultural and
      ed  land scenarios, the  following equation is used for both inorganic  and organic
  reclaimed  land  scenarios,
  pollutants:
                              1          (N -AR) + MS

 where:
                                                                                 4
               =     concentration of pollutant  j in sewage sludge-amended  soil (mg
                     pollutant/kg sewage sludge-amended soil),
               =     background concentration  (dry  weight) of pollutant j  hi  soil (mg
                     pollutant/kg soil),                                                •
        MS    =     mass of soil hi mixing zone of one hectare of land (Mg soil/ha land),
        AT      =     total number of years sewage sludge is applied to land (yr),
        Cj      =     concentration of pollutant/ hi sewage sludge (mg pollutant/kg sewage
                     sludge), and
        AR     =     annual whole sludge application rate of sewage sludge to land (dry Mg
                     sewage sludge/ha-yr).

 The mass of soil in the mixing zone of one hectare of land is calculated as:


                                MS = BD^ • d  • lO'1     ,   .                  (4-2)
where:
       BDsoil  -    bulk density of soil (kg soil/m3 soil),
       d      =    depth of incorporation (cm), and                               .
       10'1    =    constant to convert (kg -cm/in3) to (Mg/ha).


       For forests and public contact sites,  it is assumed that there is no incorporation of
land-applied sewage sludge.  Therefore, the concentration of each pollutant in the "soil" is
set equal to its concentration in the sewage sludge.               •
                                        4-11

-------
        The concentrations of pollutants in crops grown on sewage sludge-amended soil are
 calculated as;                 .          •   '      .
                                                UC
                                                           (4-3)
 where:
        CD,.
        UC,   =
 tissue concentration (dry weight)  of pollutant j  in crop  /  (mg
 pollutant/kg crop tissue), and
 rate of uptake of pollutant j into tissue of crop i (jig pollutaut/g dry
 weight crop tissue per fig poUutant/g sewage sludge-amended soil).
 Exposure Equation
        Once the various concentrations of a pollutant in crop tissues are estimated, they are
 combined with data on the fraction of crops grown on sewage sludge-amended soil and the
 daily dietary consumption of crops to estimate human exposure:
                                  1Q-3
                                  BW
                                  icr3 CT.
                       CDfJ FCf DCt
                                    BW
                                         1 £  UC, PC, DC
where:
       10-3    =
       BW    =
       DC;    =

Data Inputs
exposure to pollutant./ from crops produced on sewage sludge-amended
soil (mg pollutant/kg body weight-day),
constant to convert units from (g) to (kg),
body weight (kg), assumed to be 70 kg,
fraction of dietary consumption of crop / grown in sewage sludge-
amended soil (dimensionless), and
daily dietary consumption  of crop / (g crop tissue/day).
       There are three types of  data  inputs  specific  to this pathway:   daily dietary
consumption of various crops, fraction of consumption derived from sewage sludge-amended
soil, and pollutant-specific plant uptake rates. Values for the daily dietary consumption of
crops and the fraction of consumption derived from sewage sludge-amended soil are presented
in Exhibit 4-5.
                                       4-12

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                                      EXHIBIT 4-5
                           Dietary Assumptions for Pathway 1
Daily Dietary Consumption
      of Crop (g dry
       weight/day)1
  Fraction of Consumption
Derived from Sewage Sludge-
       Amended Soil2
             Crop
             =
    Garden Fruits
   Grains and Cereals
   Leafy Vegetables
   Root Vegetables
   Mushrooms
                                          f°°d ***" f°r "» Cr°PS< in **.***. -less otherwise
  Fractions represent reasonable estimates, unless otherwise noted. U S EPA 1992a
  Fractions represent reasonable worst-case assumptions.  U.S. EPA, 1992a.
      _ Plant uptake slopes are needed for the seven agricultural crop categories that represent
whr. TS    ^f ^ gafden *"* (e'g" t0mat0e<* «"*» ™« steals ^g.  bSy
wheat); leafy vegetables (e.g., swiss chard, cabbage, lettuce); dry and fresh legumis (e g

        eaS);HP^anUtS;  F0tat°eS; 3nd' r°0t  Vegetables 
-------
        •      peanut  uptake slopes and  legume uptake  slopes  were considered
               interchangeable; and

        •      any vegetative or leafy growth uptake slopes.identified hi a study (e.g.,
               soybean leaves) were used for leafy vegetable uptake slopes if no leafy
               vegetable studies could be identified.

        When multiple data points were available for a particular pollutant and crop from a
 variety of studies, the average of the data from the most appropriate studies was used.  The
 appropriateness of a given study  was determined  from the study  hierarchy established in
 Round One: data from sludge-amended field studies were preferred over data from sludge-
 amended pot studies, which hi turn were preferred over data from metal-salt-amended field
 or pot studies.  If. uptake  slope data existed for a particular pollutant hi a particular crop
 category from more than one study of the same hierarchical level, they were averaged.

        For the agricultural pathway, if uptake slope data were not available or could not be
 estimated using the above extrapolations for all seven crops for a particular pollutant, then
 exposure to that pollutant was not estimated. Available plant uptake slopes for agricultural
 land crops are presented hi Exhibit 4-6.  Note that only 14 pollutant candidates had available
 data on plant uptake slopes for at least one crop; only three pollutant candidates had uptake
 slope data available for all  seven crops.  Therefore only three pollutants could be evaluated
 for this exposure pathway.                                                           -

       The non-agricultural Pathway 1 models human consumption of plants grown hi forests,
 on reclaimed lands, or on public contact sites that have been amended with sewage sludge!
 Humans are  assumed to be potentially  exposed to wild berries or mushrooms.   For this
 pathway, garden fruits were used as a surrogate for berries if actual data did not exist for
 organic and inorganic pollutant uptake.  For uptake of organic and inorganic pollutants .into
 mushrooms,  data were  not  available.   In the Technical Support Document for Land
 Application of Sewage Sludge (U.S. EPA,  1992a),  it was noted that mushrooms have
potential to bioaccumulate both mercury and cadmium.  As shown hi Exhibit 4-7, information
is not available on whether mushrooms can bioaccumulate any of the Round Two pollutant
candidates. Note that only four pollutant candidates, those with available wild berry uptake
data, are included hi the exhibit.  No pollutants could  be evaluated  for the non-agricultural
pathway due to the lack of uptake data for mushrooms.
                                       4-14

-------
4-15

-------
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4-16

-------
                                       EXHIBIT 4-7
               Available Plant Uptake Slopes for Non-Agricultural Pathway 1
                       Pollutant
             Dioxinsand Dibenzofurans
             Fluoride
                                                   Plant Uptake Slopes
                                              Qtg/g crop tissue per >g/g soil)
                                               0.0000362
  Key to Study Type:
  A: Studies conducted in the field with sewage sludge.
  B: All other studies conducted with sewage sludge.
  C: All other studies.

  Footnotes:
  1 Soon and Bates, 1985 (com kernels: 2.29): A.
  2 U.S. EPA, 1992b.  Estimated from model. Assumed dry weight basis
   Doss et al., 1977 (tomatoes: 0.35): C.
 4 Tonkpnozhenko and Khlyupina, 1974 (corn kernels: 0.136): C.
 Example Exposure Calculation for Pathway 1

' -   '   The following example presents the calculations for estimating human exnosure to
using £0^-2* 6
                      °f
                                                MS' fa 6Stimated f°r •&***** land by
where:
       1600   =
       15     -
       10     =
                    MS.- Jggfe  .-!<,-,'.
                                                         _ 2400Afg
                                            kg • cm/m3       ha
                    BDsoit (bulk density of soil) from Exhibit 4-3,
                    d (depth of incorporation for agricultural land) from Exhibit 4-3  and
                    constant to convert (kg •cm/m3) to (Mg/ha).

       Then, the concentration of fluoride in agricultural soil is calculated using Eq. 4-1:
                                        4-17

-------
               CT
                 fluoride
                       = 230mg/kg
 where:
        220   =    BSj (background concentration of fluoride in soil) from Exhibit 4-4,
        2400  =    MS (mass of soil hi agricultural mixing zone), estimated above,
        20    =    N (total number of years sewage sludge is applied to agricultural land)
                    from Exhibit 4-3,
        411   =    Cj (fluoride concentration hi sewage sludge) from Exhibit 4-1, and
        7      «    ^(application rate of sewage sludge to agricultural land) from Exhibit
                    4-3.

       Total dietary exposure is then determined using Eq. 4-4:
                                       ] . [(0.35*/g - 0.025 - 4.15g/day)

                   + (0.44gfg • 0.025 • 90.7g/day)  + (L9g/g • 0.025 - L91g/day)

                   + (2.2g/g • 0.025  • %.15glday) + (2.2g/g • 0.025 • 2.2Sg/day)

                   + (0.25^/g •  0.025 • 15.6gfday)  + (0.25g/g - 0.025 • L6g/day)]

                = 0.0061mg/kg-day
where:
       10"                 =     constant to convert units from (g) to (kg),
       230                =     CZ} (concentration of fluoride  hi  agricultural soil),
                                 estimated above,
       70                  -     5W(body weight), assumed to be 70 kg,
       0.35-0.025-4.15   =     contribution to dietary exposure from garden fruits,
       0.44-0.025-90.7   =     contribution to dietary exposure from grains and cereals,
       1.9 • 0.025 • 1.97    =     contribution to dietary exposure from leafy vegetables,'
      2.2 • 0.025 • 8.75    =     contribution to dietary exposure from legumes,
      2.2 • 0.025 • 2.25    =     contribution to dietary exposure from peanuts,
      0.25 • 0.025 • 15.6   =     contribution to dietary exposure from potatoes, and
      0.25-0.025-1.6    =     contribution to dietary exposure from root vegetables.
                                      4-18

-------
   Contribution to dietary exposure is derived as the product of UCy (uptake slope of fluoride
   into crop) from Exhibit 4-6, FCt (fraction of dietary consumption of crop grown in sewage
   sludge-amended soil) from Exhibit 4-5,  and DC, (daily dietary consumption of crop) from
   Exhibit 4-5.                                                                 *   .
  4.2.2  Pathway 2 - Ingestion of Crops Grown in Sewage Sludge-Amended Home Gardens

         Pathway 2 evaluates human ingestion of plants that have taken up pollutants from
  sewage sludge-amended home gardens.  The mass balance and exposure equations used are
  identical to those  for Pathway 1 (Section 4.2.1).

  Data Inputs

         There  are  three types  of data inputs  specific to this pathway:  the daily dietary
  consumption of specific crops, the fraction of that daily consumption that comes from sewage
  sludge-amended home gardens, and pollutant-specific plant uptake slopes.  Values for
  daily dietary consumption of crops and the fraction of consumption derived from sewage sludg
  amended soil are presented in Exhibit 4-8.
   Garden Fruits
   Grams and Cereals
  •~""™-~^™— •— ™— ™™— ^«_
   Leafy Vegetables
  "
   Fresh Legumes
  Potatoes
  Root Vegetables
  Sweet Corn
                                    EXHIBIT 4-8
                          Dietary Assumptions for Pathway 2
                                  Consumption of Crop
(g/day)1
 ==

  4.15
 •^•^^H^V^

  89.1
 •— ™»™

  1.97
. 3.22
 15.6

 1.60
TOp
=====






Fractio
Derived f
A
=====






           -^
Amended Soil2
     ==

     0.58
    0.0043
                              0.58
    0.58
    ^MM^H^^H

    0.37
                                                                      0.58
 Values represent-the estimated lifetime average daily food intakes for the crops US EPA  1992a
 Values are for a Highly Exposed Individual. U.S. EPA, 1992a.
         7 UP       *? ** Deeded f°r ** Seven Cr°Ps ** ******* major human dietary
aer^r/r?0^ fTi^ *** ^^^ garden ^^ 
-------
   legumes (e.g., beans, peas); potatoes; root vegetables (e.g., carrots, beets); and sweet corn
   (U.S.  EPA, 1992a).  Note that there  are three differences between these crops and  the
   agricultural crops used to evaluate exposure in Pathway 1.  First, only fresh legumes  are
   considered for Pathway 2, not both fresh and dry, because home gardeners do not usually
   grow the dried legumes they consume.  Second,  peanuts are not considered in Pathway 2,
   also because home gardeners do not usually grow the peanuts they consume. Third, sweet
   corn is separated out as a food group for home .gardeners because so many gardeners grow
   sweet corn. In Pathway 1, sweet corn is included in the category of cereals and grains  In
  Pathway 2, the percent of sweet corn that is homegrown differs from the percent of grains
  and cereals that are homegrown, and thus the two food categories are separated, the non-
  agricultural crops of Pathway  1, berries and mushrooms, which are grown on forest land
  reclaimed sites, and public contact sites, are not considered relevant for home gardens.

         Data on plant uptake slopes did not exist for all pollutant candidates and for all crops
  When no data  were available for a particular crop, the following extrapolations were made
  between crops  for a given pollutant:

         •      grain and cereal uptake slopes and forage/pasture uptake slopes (used
               in animal exposure pathways) were  considered interchangeable;

         •     potato uptake slopes and root vegetable uptake slopes were considered
              interchangeable;                                                    ' •    ~

        •     peanut uptake slopes  and legume  uptake  slopes were considered           ^^
              interchangeable;  and

        •     any vegetative or leafy growth uptake slopes identified in a study (e.g
              soybean leaves) were used  for leafy vegetable uptake slopes if no leafy
              vegetable studies could be  identified.

       When multiple data points were available for a particular pollutant and crop from a
 variety of studies, the average of the data from the most appropriate studies was used  The
 appropriateness  of a given study was determined  from the  study hierarchy established in
 Round One:  data from sludge-amended field studies were preferred over data from sludge-
 amended pot studies, which in turn were preferred  over data from metal-salt-amended field
 or pot studies. If uptake slope data existed for a particular pollutant in a particular crop from
 more than one study of the same hierarchical level,  they were averaged.        -

       Even  after all of the above extrapolations  were made, many pollutants still had data
 gaps.. If uptake slope data were not available or could not be estimated using  the above
 extrapolations for all seven crops for a particular pollutant, then exposure to that pollutant
 was not estimated.  Available plant uptake slopes are presented in Exhibit 4-9.  Note mat the
 exhibit includes only the  14 pollutant candidates for  which there were uptake data for at least
^nr°P' ,  ?y **$ P°Uutant candidates CPOM te ev^ted for this exposure pathway
because only.three pollutant candidates had uptake slope data available for all seven crops
                                        4-20

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                   4-22

-------
  Example Exposure Calculation for Pathway 2


        The following example presents the calculations for estimating human exposure to
  fluoride in sewage sludge applied to a home garden.  The example uses the equations and
  input data presented above for Pathway 2.


       JFirst, the mass of soil in the mixing zone, MS, is estimated for a home garden by
  using Eq. 4-2:



                    MS = 1600*g  - 15cm .  W^Mg/ha  =  2400Mg

                            m3           . kg  - cm/m3      ha

 where:

        1600   =     BDsoil (bulk density of soil) from Exhibit 4-3,

        fill    =     d (4epth °f mc°IP°ration for agricultural land) from Exhibit 4-3  and
        10-    -     constant to convert (kg - cm/m3) to (Mg/ha).


       Then, the concentration of fluoride in soil is calculated using Eq. 4-1:
                        (220mg . 2400Af£J + /;  .4llmg    7Mg

             CT^ = Li_	ha  }   (  	 kg     ha.,.
                                         ha-yr j      ha



                     = 230mg/kg
where:
                       (back8round concentration of fluoride in soil) from Exhibit 4-4

      oo           Sv (maSS °f S0il " h°me garden mbdnS zone>' estimated above,  '
      20     -     N (total number of years sewage sludge is applied to home garden)
                   from Exhibit 4-3,

      411    =     q.(fluoride concentration in sewage sludge) from Exhibit 4-1 and

      7      -     ^(application rate of sewage sludge to home garden) from Exhibit 4-
                                     4-23

-------
        Total dietary exposure is then determined using Eq. 4-4:
                                                       0.58
                               • 0.0043  • S9.1g/day)  + (l<9g/g • 0.58  • 1.97g/day)

                               0.58 • 3.22g/day) + (0.25g/g • 0.37

                    - (0.25g/g -  0.58  • 1.6g/day) + (0.35^ • 0.58

                 = Q.03lmg/kg-day
 where:
        10~3                    =  constant to convert units from (g) to (kg),
                                                                         ,
        230                    =   C3} (concentration of fluoride in agricultural  soil),
                                   estimated above,
        70                     =   BW (body weight), assumed to be 70 kg,
        0.35 • 0.58 -4.15       =   contribution to dietary exposure from garden fruits,
        0.44-0.0043-89.1     =   contribution to  dietary  exposure from  grains and
                                   cereals,
        1.9 • 0.58  • 1.97 .        =   contribution to dietary exposure from leafy vegetables,
       n'?c °n5?  " 3"22         =   contributi°n to dietary exposure from fresh legumes, '
       0.25 • 0.37 • 15.6        =   contribution to dietary exposure from potatoes,
       0.25 • 0.58 - 1.6         =   contribution to dietary exposure from root vegetables,
                                   and                                      •      '
       0.35-0.58-1.6         =   contribution to dietary exposure from sweet com.

Contribution to dietary exposure is derived as the product of UCfj (uptake slope of fluoride
into crop) from Exhibit 4-9, FCt (fraction of dietary consumption of crop grown in sewage
gidge-amended soil) from Exhibit 4-8,  and DC, (daily dietary consumption of crop)  from
                                       4-24

-------
   4.2.3 Pathway 3 - Direct Ingestion of Sewage Sludge by Children

         Pathway 3 evaluates children's exposure to pollutants from direct ingestion of sewaee
   sludge applied to land.  The agricultural and non-agricultural scenarios are different  in their
   assumptions regarding the age of children who ingest sewage sludge.  At agricultural and public
   contact sites, children ages 1 to 6 are assumed to be exposed, whereas forforest and reclaimed
   sites, only older children ages 4 to 6 are assumed to have the opportunity for exposure  For all
   scenarios, children are assumed to be exposed directly to sewage sludge from storage piles or
   from the soil surface, not to a sewage sludge/soil mixture.

   Data Inputs and Exposure Equation

         As in Round One, children (ages 1 to 6) exposed to agricultural land and public contact
  sites are assumed to ingest 0.2 g soil (dry weight) per day, and weigh  16  kg.  Older children
  (ages 4 to 6) exposed to forest and reclaimed sites are assumed to ingest 0.2 g soil per day  and
  Wp?r A  HM",   ™mf ?^ me °f °'2 g SOU P£r day is a high-end value, but does not represent
  a PICA child.  The body weights are average  values.  Exposure is calculated as:
                                        =	—1.                            (4-5)

 where:
        EXPj   =     exposure to pollutant y in sewage sludge (mg pollutant/kg body weight-
                     day),                                                          &
        IS ^    =     sewage sludge ingestion rate (g sewage sludge/day),
        10-     =     constant to convert units from (g/day)  to (kg/day)
        q     =     concentration of pollutant j in sewage sludge  (mg pollutant/kg sewage
                     sludge), and                                               "
       BW    =     body weight (kg).

 Example Exposure Calculation for Pathway 3

       The exposure of a child to fluoride from directly ingesting sewage sludge applied to
 agricultural land can be estimated from Eq. 4-5:                                 
-------
        10~*    =     constant to convert (g) to (kg),
        411    =     Cj (concentration of fluoride in sewage sludge) from Exhibit 4-1, and
        16     =     BW (body weight of child assumed to be exposed to  agricultural land),
                     from-Methods section above.
 4.2.4  Pathway 4 - Ingestion  of Animal  Products Produced From Animals Consuming
        Forage/Pasture Grown on Sewage Sludge-Amended Soil
                       i                                .
        Pathway 4 calculates human exposure to pollutants through consumption of animals that
 ingest forage/pasture grown on sewage sludge-amended soils.  In the agricultural Pathway 4,
 animals ingest forage and pasture produced oh sewage sludge-amended soil. Humans then ingest
 animal products,  such as beef, pork, lamb, poultry,  dairy products,  and eggs.   The  non-
 agricultural Pathway 4 examines human exposure to pollutants through consumption of deer and
 elk that forage on sewage sludge-amended forest land and reclaimed land.

 Methods

        As in Pathways 1 and 2, to  be conservative, the entire mass of pollutant applied  in
 sewage sludge over the life of a land application site is assumed to be available for plant uptake
 (see Section 4.2.1).  In calculating total pollutant concentration hi the soil for the agricultural
 and reclaimed land scenarios, Eq. 4-1 from Section 4.2.1 is used for inorganics and organics.
 The expected concentrations of pollutants hi forage/pasture grown on sewage sludge-amended
 soil are then estimated using Eq. 4-3 from Section 4.2.1.

       To estimate concentrations of pollutants hi animal tissues, the forage/pasture  pollutant
 concentrations are combined with animal uptake rates.   In this calculation it is assumed that
 forage is 100 percent of the animal's diet:
                                                   Ujk                           (4-6)

where:
                '    =     concentration of pollutant j in animal product k (mg pollutant/kg
                           animal tissue),
                    -     tissue concentration (dry weight) of pollutant/ in forage/pasture
                           (mg pollutant/kg forage/pasture), and
       ujt           =     rate of uptake of pollutant y into animal product k (mg pollutant/
                           kg dry weight animal tissue per mg pollutant/kg dry weight diet).

       Once the concentrations of pollutants hi animal tissues have  been estimated,  they are
combined with data on the daily dietary consumption of animal products and on the fraction ,of
these  animal products that are produced  on sewage sludge-amended soil to estimate human
exposure:                                                                                  ^^
                                         4-26

-------
 where:
       EXPj
       lO'3    =
       BW    =
       FAk    =

       DA,    =
Data Inputs
                                 IP
                                   -3
                                                                                (4-7)
                                 ID'3 CD.
                                        forage, j
                                     BW
                           £
                            k
                                                   UjkFAkDAk
exposure to pollutant j from animal products produced on sewage sludge-
amended soil (mg pollutant/kg "body weight-day),
constant to convert units from (g) to (kg),
body weight (kg), assumed to be 70 kg,
fraction of dietary consumption of animal product k produced on sewage
sludge-amended soil (dimensionless), and
daily dietary consumption of animal product k  (g dry weight animal
product/day).
       This pathway requires data on pollutant uptake  rates into forage/pasture and animal
products as well as data on daily  dietary  consumption of specific animal products and the
fraction of that daily consumption that comes from animals feeding on forage/pasture produced
on sewage sludge-amended soil.  Values used for the latter two parameters are shown in Exhibit
4-10.    •
                                   EXHIBIT 4-10
                         Dietary Assumptions for Pathway 4
Animal Product
Beef (lean)
Beef Fat
Beef Liver (lean and fat)
Dairy (non-fat)
Dairy Fat
Eggs
Lamb (lean)
Lamb Fat
Daily Dietary
Consumption of Animal
Product (g/day)1
19.3
15.5
1.1.
28.9
18.1
8.3
0.20
0.21
Fraction of Consumption
Derived from Sewage
Sludge-Amended Soil2
9.7xlO'2
9.7xlO'2
9.7xlO'2
S.lxlO'2
S.lxlO"2
7.9xlO'2
9.7xlO'2
9.7xlO-2
                                       4-27

-------
                                        EXHIBIT 4-10
                         Dietary Assumptions for Pathway 4 (cont'd.)
Animal Product
Poultry (lean)
Poultry Fat
Pork (lean)
Pork Fat
Deer (lean)
Deer Fat
Deer Liver (total)
Elk (lean)
Elk Fat
Elk Liver (total)
Daily Dietary
Consumption of Animal
Product (g/day)1
6.7
' 1.3
. 9.0
12.7
15.33
5.13
0.383
30.63
10.23
0.763
Fraction of Consumption
Derived from Sewage
Sludge-Amended Soil2
l.lxlO'1
1.1x10-'
9.7xlO'2
9.7xlO-2
1
1 .
1
0.5
0.5
0.5
 ' Values represent the estimated lifetime average daily food intakes for the animal products unless otherwise noted  U S
 EPA. 1992a.
 : Fractions represent reasonable estimates. U.S. EPA, 1992a.
 ' It was assumed that total consumption of deer and elk meat and fat constitutes 50 percent of the HEI's consumption
 of agricultural animal products. U.S. EPA.  1992a.

        If no data were available on  pollutant uptake slopes into forage/pasture, it was assumed
 that grain and cereal uptake slopes and  forage/pasture uptake slopes were  interchangeable.
 When multiple data points were available from a variety of studies for the uptake  of a particular
 pollutant into forage/pasture crops, the average of the data from the most appropriate studies was
 used.  The appropriateness of a given study was determined from the study hierarchy established
 in Round One: data from sewage sludge-amended field studies were preferred over data from
 sewage sludge-amended pot studies, that in turn were preferred over data from metal-salt-
 amended field or pot studies.  If uptake slope data existed for a particular pollutant from more
 than one study of the  same hierarchical level, they were, averaged.

       Available plant uptake data are presented in Exhibit 4-11.   Note that if forage/pasture
uptake data were not  available for a particular pollutant,  that pollutant is not included in the
exhibit.
                                           4-28

-------
                                        EXHIBIT 4-11
                  Forage/Pasture Uptake Slopes for Agricultural Pathway 4
                         Pollutant
           Aluminum
           Beryllium
           Boron
           Dioxihs and Dibenzofurans
           Fluoride
            Manganese

            Polychlorinated biphenyls (coplanar)
            Silver
                                                    Forage/Pasture Uptake Slopes
                                                       Qtg/g plant per ftg/g sou)
 Key to Study Type:
 A: Based on sewage sludge field study.
 B: Based on non-field sewage sludge study.
 C: Based on non-sewage sludge study.

 Footnotes:
 1 Muchovej et al., 1986 (ryegrass: 3.13): C.
 2 Bonn and Seekamp, 1979 (oats: 0.31): C.
 3 Soon and Bates, 1985 (bromegrass: 1.64): A.
 * U.S. EPA, 1992d. Estimated from model

 DO* =,
                                          ): c:
                                                                3.131
                                                                0.312
                                                                3,9s
                                                                0.0244
                                                              0.67755
                                                                8.226
                                                                  ^^Hm
                                                                2.07
                                                               0.0218
                                                                                  « 0.33):
8 Romney et al., 1977 (barley: 0.021): C
» Tonkonozhenko and Kblyupina, 1974 (winterwheat leaves+stem: 0.07, clover leaves + stems: 0.063, rice: 0.03): C.

For non-agncultural am
                           products, however, tissue values for sheep,  goats  dee
                                             HVCr ^ -*«ta.^S
                                           -  For coplffiar PCBi- """^ vataes were
                                          4-29

-------
       Exhibit 4-12 presents the available  animal uptake slopes for the agricultural animal
products of interest; Exhibit 4-13  presents the available uptake slopes for non-agricultural
animals. As before, note that only those pollutant candidates with data for at least one animal
uptake slope are included hi the exhibits.
                                         4-30

-------
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                          4-31

-------
                                      EXfflBIT4-13
                  Animal Uptake Slopes for Non-Agricultural Pathway 4
Pollutant
Aluminum
Barium
Boron
Manganese
• Polychlorinated
biphenyls (coplanar)
Animal Uptake Slopes Qtg/g animal per /tg/g feed) -
Deer
(Lean)
0.021 l
0.0883
0.0911
0.009254
NA
Deer
Fat
NA
NA
NA
NA
4.2152
Deer
Liver
0.0071
0.05353
0.09151
0.009254
6.6642 '
Elk
(Lean)
0.021 '
0.0883
0.091 l
0.009254
NA . ,
Elk
Fat
NA
NA
NA
NA
4.2152
Elk
Liver
0.0071
0.05353
0.09151
0.009254
6.6642
 NA means Not Applicable.
 1 Bray et al., 1985 (goat).
 2 U.S. EPA, 1992a.
 •'Whelan, 1993 (sheep:muscle).
 4 Bray et al., 1985 (goat); Voigt et al., 1988 (beef).
 Example Exposure Calculation for Pathway 4

       The following example presents the calculations for estimating human exposure to boron
 from consumption of deer and elk which have eaten forage plants on forest lands amended with
 sewage sludge. Because it is assumed that there is no incorporation of sewage sludge into forest
 soils, the concentration  of boron hi sewage sludge is used as the relevant  concentration  for
 uptake into the forage.  The concentration of boron in forage is calculated using Eq. 4-3:
       CD
       ^"
                                    boron
                                         = 182
                                           18Z ~~
                                                         V-gg
                                         = 710 mg/kg
where:
       182    =

       3.9
  j (concentration of boron in forest soil, equivalent to the concentration
of boron in sewage sludge) from Exhibit 4-1, and
   y (uptake slope of boron into forage/pasture) from Exhibit 4-11.
                                          4-32

-------
         Total dietary  exposure to boron  from wild animals eating plants  in sewage sludge-
  amended forests is then determined using Eq. 4-7:
                         1-3
                       + (0.092g/g • 1 • 0.3Sg/day) + (Q.09lg/g ' 0.5  - 30.6g/day)

                     •  + (0.092g/g • 0.5 - Q.76g/day)]

                    = Q.Q29mg/kg-day
  where:                                                                         "
        10"3                 =     constant to convert units from (g) to (kg),
        710                 -     CTj (concentration of boron in forest soil), estimated above,
        70                  =     BW (body weight), assumed to be 70 kg,
        0.091 -1-15.3      =     contribution to dietary exposure from lean deer,
        0.092 • 1 • 038       =     contribution to dietary exposure from deer liver,
        0.091 • 0.5 • 30.6    =     contribution to dietary exposure from lean elk, and
        0.092 • 0.5 • 0.76    =     contribution to dietary exposure from elk liver.

        Contribution to dietary exposure is derived as the product of UCik  (uptake slope of boron
 into animal product) from Exhibit 4-13, FAk (fraction of dietary consumption of animal product
 derived  from  sewage  sludge-amended soil)  from  Exhibit  4-10,  and DAt (daily dietarv
 consumption of animal product) from Exhibit 4-10.                            .


 4.2.5 Pathway 5 - Consumption of Animal Products Produced From Animals That Insest
       Sewage Sludge                        „                                     e

       Pathway 5 involves the application  of sewage sludge to land, the direct ingestion of
 sewage sludge by  animals,  and  finally, the consumption of animal  products  by humans
 Agricultural Pathway 5 considers only the direct  ingestion of sewage sludge  by livestock
 following the surface application of sewage sludge to pasture crops.  Non-agricultural Pathwav
 5 considers the direct ingestion of sewage sludge by livestock that graze on grasses growing on
 forest land or reclaimed land; the animals are then ingested by humans.  The pathway does not
 consider the grazing of livestock  on public contact sites because it is assumed such grazing
 would .be controlled.  The pathway also does not consider wild animals in forest land because
 deer do not graze on plants close to the ground and would not inadvertently ingest sewage
 sludge.  Furthermore, other wild  herbivorous game animals are assumed to grazl over large
 territories.                                                                          °

 Methods

      To estimate  concentrations of  pollutants in animal tissues, sewage sludge pollutant
concentrations are combined with percent of animal ingestion that is sewage sludge and tissue
uptake rates.  In this calculation the sewage sludge pollutant concentration multiplied by the

                     -                    4-33

-------
  animal's percentage sewage sludge consumption and pollutant uptake rate is assumed to equal
  the resulting animal tissue concentration of the pollutant:
  where:
        CAU
        FS
                                   CAjk  = C.  • FS  - U.k
                                                             (4-8)
        concentration of pollutant j in animal product k (mg pollutant/kg
        animal tissue),
        concentration of pollutant j in  sewage sludge (mg pollutant/kg
        sewage sludge),
        fraction of animal's diet that is sewage sludge (unitiess, kg sewage
        sludge/kg diet), and
        rate of uptake of pollutant/ into animal product k (mg pollutant/
        kg dry weight animal tissue per mg pollutant/kg dry weight diet).
        Once the concentrations of pollutants in animal tissues have been estimated, they are
 combined with data on the daily dietary consumption of animal products and on the fraction of
 those animal products that are produced on sewage  sludge-amended  soil to estimate human
 exposure:
                                  "3
                              = 4L 2:  CA*FA* DAt
 where:
       ID'3
       BW
       FAk

       DAt
                                 10
                                   -3
                   CJ
FS
                                     BW
                                                   UjkFAtDAt
                                                                                 (4-9)
exposure to pollutant/ from animal products produced oh sewage sludge-
amended soil (mg pollutant/kg body weight-day),
constant to convert units from (g) to (kg),
body weight (kg), assumed to be 70 kg,
fraction of dietary consumption of animal product k produced on sewage
sludge-amended soil (dimensionless), and
daily dietary consumption of animal product k (g dry weight annual
product/day).
Data Inputs

       For this pathway, there are four data inputs required to calculate human exposure from
consumption of animal products produced from animals that ingest sewage sludge: the percentage
of animal diet that consists of sewage sludge, the daily dietary consumption of specific animal
                                        4-34

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  products, the fraction of that daily consumption .which comes from animals that ingest sewage
  sludge, and animal uptake rates of pollutants.

        The percentage of a grazing cattle's diet that is sewage sludge, averaged over a season,
  is estimated to be 2.5 percent (Chaney et al.,  1987; Bertrand et al., 1981). However, given that
  in any one year, the maximum percentage of a farm treated with sewage sludge is approximately
  33 percent, and assuming that livestock are rotated among several pasture fields,  the actual
  percentage of the diet that is sewage sludge is assumed to be lower than 2.5 percent.  The diet
  for cattle grazing  on land treated with sewage sludge that was applied the previous growing
  season has been shown to be approximately  1.0 percent sewage sludge (Decker et al., 1980)
  When a weighted average is calculated from these two values of sewage sludge ingestion, the
  long-term average percentage of diet that is sewage sludge  is 1.5 percent:  V3(2.5%) + %fl 0%)
  = 1.5%  (Chaney etaL, 1991).                   .                          .  .

        Values for  the daily  dietary human consumption of specific animal products and the
  fraction of consumption from sewage sludge-amended soil are shown in Exhibit 4-14   For
  animal uptake slopes for beef, dairy, and lamb products,  see Exhibit 4-12 in Section 4.2.4.

                                     EXHIBIT 4-14
                           Dietary Assumptions for Pathway 5
  Beef (Lean)
  Beef Fat
  Beef Liver
Dairy (Non-Fat)

Dairy Fat

Lamb (Lean)
  Lamb Fat
roduct
=========


)



Daily Dietary
Consumption of A
Product (g/day
19.3
15.5
1.1
28,9
18.1
0.20
0.21
                                                       Fraction of Consumption
                                                         Derived from Sewage
                                                         Sludge-Amended Soil2
                                                        	=====
                                                               9.7xlO'2
                                                                  9.7xlO-2
                                                                 S.lxlO'2
                                                                 S.lxlO-2
                                                                 9.7xlO'2
                                   ^S^Sj^^SSS^SS^^SE^^S^^^^^^^s:^^^^^^^^^^^^^^^~^~^^^^^m^^
                                   : daily food intakes for the animal products unless otherwise noted. U.S.

 : Fractions represent reasonable estimates. U.S. EPA, 1992a.
Example Exposure Calculation for Pathway 5

       The following example presents the calculation for estimating human  exposure to
manganese from consumption of livestock that ingest sewage sludge on sewage sludge-amended
forest land.  Using Eq. 4-9:                                       .
                                         4-35

-------
   EXP.
       manganese
                  io-3**  . 1620-22  • 0.015
                           70kg
                   [fo.00925^ • 9.7xlO~2 • 1.1-S-} +
                   \     .   8                day)
                 fo.0005^ - 9.7x20-z • 19.3-3-} + fo.00925^ • 9.7x10-2 - 0.20-M
                 \       8                 day)   (       g                day)
V
g
                                          day
                 8.9xlO-7—™8__
                         kg-day
 where:
        io-3
        1620

        0.015

        70
        (0.00925 -9.7xlO-2 -1.1)

        (0.0005 • 9.7 x IO-2 • 19.3)

        (0.00925 - 9.7 x 10'2 • 0.20)

        (0.0005 -3.1 xlO'2 -28.9)
                       constant to convert units from (g) to (kg),
                       Cj (concentration of manganese in sewage
                       sludge) from Exhibit 4-1,
                       FS (fraction of animal's diet that is sewage
                       sludge), discussed above,
                       BW(]body weight), assumed to be 70 kg,
                       contribution to dietary exposure from beef
                       liver,
                       contribution to dietary exposure from lean
                       beef,
                       contribution  to dietary exposure, from lean
                       lamb, and
                       contribution  to dietary exposure from non-
                       fat dairy.
 Contnbution to dietary exposure is derived as the product of Uf (uptake of manganese into
 animal product) from Exhibit 4-12, FAk (fraction of dietary consumption of animal product
 derived from sewage  sludge-amended land),  from Exhibit 4-14,  and DAk (daily  dietary
 consumption of animal product) from Exhibit 4-14.


 4.2.6  Pathway 6 - Animal Toxicity From Plant Consumption

       Pathway 6 calculates herbivorous animal toxicity caused by the consumption of plants that
 are grown on sewage sludge-amended soil on both agricultural and non-agricultural lands  Non-
 agncultural lands include forests, reclaimed land,  and public contact sites. In the agricultural
 pathway, the HEI is the most sensitive herbivorous livestock that consumes plants grown on
 sewage sludge-amended soil.  For  the non-agricultural forest land Pathway 6, two exposure
 scenarios are possible.  In one, the HEI is a small herbivorous mammal that spends its entire
 life in a sewage  sludge-amended area feeding on seeds and small plants close to the sewage
sludge/soil layer. In the second scenario, the HEI is an herbivorous livestock that grazes on the
                                      .  4-36

-------
  grasses  growing on sewage sludge-amended forest  land:   The HEI for reclaimed land is
  livestock; the HEI for public contact sites is a small herbivorous mammal.
  Methods
         For the agricultural Pathway 6, the animals of interest are herbivorous livestock.  For
  the non-agricultural Pathway 6, the .animals of interest are small herbivorous mammals as well
  as herbivorous  livestock.   Eq.  4-1 from Section 4.2.1  is used to calculate total pollutant
  concentration in the soil (C7}) for the agricultural and reclaimed land scenarios.   Exposure is
  reported in terms of milligrams pollutant per kilogram of diet, assuming  that the herbivore
  receives its total diet from forage/pasture grown on sewage sludge-amended land   Therefore
  the dietary exposure for the HEI can be expressed as:                                    '
                                                                                 (4-10)


 where:
        EXPAJ       =     exposure of animal to pollutant./ (mg pollutant/kg diet),
        CDJ          ~     ti85116 concentration (dry weight) of pollutant j in forage/pasture
                            (mg pollutant/kg forage/pasture),
        01 i          -     concentration of pollutant j in sewage sludge-amended soil (mg
                            pollutant/kg sewage sludge-amended soil), and
        UCforageJ      =     rate of uptake of pollutant j into  tissue of forage/pasture (mg
                            pollutant/kg dry weight forage/pasture per mg pollutant/kg soil).

 Data Inputs

       For this pathway, data are needed on pollutant uptake rates into  forage/pasture   For
 available uptake rates into forage/pasture, see Exhibit 4-11 in Section 4.2,4.

 Example Exposure Calculation for Pathway 6

 live^n 5"°^ ^"^^ ^^ ** ^^^^ for estimating exposure of herbivorous
 livestock to fluoride in sewage sludge applied to agricultural land.

 E   4_2FirSt' ^ maSS °f S0il fa ** mbcmg zone' MS>  is estimated for agricultural land by using
                     MS =       g • i5cm .  W~Mg/ha =  2400Mg
                             m3            kg ' cm/m3      ha
where:
       1600  =     BDSOU (bulk density of soil) from Exhibit 4-3,
       15    =     d (depth of incorporation for agricultural land) from Exhibit 4-3 and
       iu    -     constant to convert (kg -crn/m3) to (Mg/ha).
                                         4-37

-------
        Then, the concentration of fluoride in agricultural soil is calculated using Eq. 4-1:
                          (22Qmg   24QQMg\   /.,.
                „    •  _(-*-—•ri'i**
                  ' fhtoridf
                  *                20yr • -2ML  + MM**
                                   V      ha-yr)      ha

                        - 230mgfkg
 where:
        220   =    55y (background concentration of fluoride hi soil) from Exhibit 4-4,
        2400  =    JWS (mass of soil in agricultural mixing zone), estimated above,
        20    =    N (total number of years sewage sludge is applied to agricultural land)
                    from Exhibit 4-3,
        411   =    Cj (fluoride concentration in sewage sludge) from Exhibit 4-1, and
        7      =    AR (application rate of sewage sludge to agricultural land) from Exhibit
                    4-3.

        The expected exposure of livestock to fluoride hi forage/pasture is calculated usins
 Eq. 4-10:               .                      '


                                                                                       0
                             EXP      = 230mS .  0.68g
                                          kg      g

                                       = 160 mg/kg

 where:             "...
       230   =     CTj (concentration of fluoride in agricultural soil), estimated above, and
       0.68  =
ucforage.j (uptake slope of fluoride into forage/pasture) from Exhibit 4-11.
4.2.7  Pathway 7 - Animal Toxicity From Direct Ingestion of Sewage Sludge

       This pathway calculates herbivorous animal toxicity caused by the direct ingestion of
sewage sludge on both agricultural and non-agricultural lands.  Non-agricultural lands include
forests and reclaimed land. For both the agricultural and non-agricultural pathways, the HEI
is the most sensitive or most exposed "herbivorous livestock that directly ingests sewage sludge
from sewage sludge-amended soil. This pathway does not consider exposure to sewage sludge
on public contact sites because livestock usually are not grazed there.

Methods

       For both the agricultural  and non-agricultural  Pathway 7, the HEI is herbivorous
livestock.  Exposure is reported in terms of milligrams pollutant per kilogram of diet, assuming
                                       4-38

-------
  that the herbivore receives its total diet from forage/pasture grown on sewage sludge-amended
  land.  Therefore, the dietary exposure for the HEI can be expressed as:


                                    EXPAj  = Cj -FS                             (4-11)


  where:
        EXPAj =     exposure of animal to pollutant j (mg pollutant/kg diet),
        Cj     =     concentration of pollutant j in sewage sludge (mg pollutant/kg sewage
                     sludge), and                            .
        FS    =     fraction of animal's diet that is  sewage  sludge  (unitless, kg  sewage
                     sludge/kg diet).

  Data Inputs

        For this pathway, data are required  on the percentage of animal  diet that consists of
  sewage sludge. As described for Pathway 5,  the percentage of a grazing cattle's diet that is
  sewage sludge, averaged over a season, is estimated to be 2.5 percent (Chancy et al   1987-
  Bertrandetal., 1981). However, given that in any one year, the maximum percentage of a fann
 treated with sewage sludge is approximately 33 percent, and assuming that livestock are rotated
 among several pasture fields, the actual percentage of the diet that is sewage sludge is assumed
 to be lower than 2.5 percent. The diet for cattle grazing on land treated with sewage sludge that
 was applied the previous growing season has  been shown to be approximately 1 0 percent
 sewage sludge (Decker et al., 1980).  When a weighted average is calculated from these two
 values of sewage sludge ingestion, the long-term average percentage of diet that is sewage sludge
 is 1.5 percent: V3(2.5%) + %(1.0%) =  1.5%  (Chaney et al.,  1991).             *

 Example Exposure Calculation for Pathway 7


                                  Uveaock " mwsansse  *- dircct tegesti°n °f
                                                    0.015
                                                is

                                             kg


where:         -
                                                                                 , and
                   FS (fraction of animal's diet that is sewage sludge), discussed above.
                                        4-39

-------
  4.2.8 Pathway 8 - Toxicity to Plants

        This pathway could not be evaluated due to a lack of data on the phytotoxicity effects of
  the candidate Round Two pollutants.


  4.2.9 Pathway 9 - Toxicity to Soil-Dwelling Organisms

        Pathway 9 evaluates toxicity to soil-dwelling organisms due to the presence of pollutants
 •in sewage sludge that is land-applied to agricultural and rion-agricultural lands. Non-agricultural
  lands include forests', reclaimed land, and public contact sites.  The soil-dwelling organisms
  considered are earthworms.  There  is no  evidence  that earthworms  are the most sensitive
  species; however,  because of a lack of data for other soil-dwelling species, earthworms are
  considered the HEI for this pathway.

  Data Inputs and Exposure Equation

        For each pollutant and type of land application site, the concentration of pollutant hi the
 soil had to be calculated. For agricultural and reclaimed land, the pollutant concentration was
 calculated using Eq. 4-1 in Section 4.2.1. For forests and public contact sites, it was assumed
 that there would be no incorporation of land-applied sewage sludge. This implies that the soil
 layer to which the soil-dwelling organisms are exposed is pure sewage sludge.  Therefore, the
 concentration of each pollutant hi the exposure layer ("soil") was set equal to its concentration
 hi the sewage sludge.   For this pathway,  exposure to  pollutants in soil by  earthworms  is
 measured by the concentration of th6 pollutants hi the sewage sludge/soil:


                                      EXPO;  = CTj                              (4-12)

 where:                                                       .
       EXPO;        =     exposure of soil-dwelling organisms to pollutant/' (mg pollutant/kg
                           sewage sludge-amended soil), and
       £2}           =     concentration of pollutant /" hi sewage sludge-amended soil (mg
                           pollutant/kg sewage sludge-amended soil).


Example Exposure Calculation for Pathway 9

       The following example estimates exposure of earthworms to manganese hi agricultural
sou.

       For agricultural land, the mass of soil in the mixing zone, MS, must first be estimated
by using Eq. 4-2:
                                         4-40

-------
                                MS = i°9°*£  . 15cm .  W-lMg/ha  = 240QMg
                                        m3            kg • cmjm3       ha
            where:
                  1600 . =     BDsoil (bulk density of soil) from Exhibit 4-3,
                  15     =     d (depth of incorporation for agricultural land) from Exhibit 4-3, and
                  10     -     constant to convert (kg • cm/m3) to (Mg/ha).

                  Then, the concentration of manganese in the soil, and thus the earthworm's exposure to
           manganese, is calculated using Eqs.  4-1 and 4-10:
                                            ?42jng •  24gOJKg  +         1620mg   ^^.  •
                CT~*_ " EXP0mangmese = US.	*"   I   I   	kg      ha-yrl
                                                      (2Qyr-™8\+~	
                                                      V       ha-yr)
                                         = 410mg/kg

          where:
^             342   -     ^(background concentration of manganese in soil) from Exhibit 4-4
                               •v 'macc nf c~'l m agricultural mixing zone),  estimated above,
                                             of years sewage sludge .is applied to agricultural  land)
                 1620  =     q (manganese concentration in sewage sludge) from Exhibit 4-1  and
                       -    AR (application rate of sewage sludge to agricultural land) fron/Exhibit
          4.2.10 Pathway 10 - Toxicity to Predators of Soil-Dwelling Organisms
                Pathway 10 evaluates toxicity to animals  feeding on soil-dwelling
          Sge *#""«*«.•** on ^th agricultural and nln^cul^
          lands include forests, reclaimed  land, and public contact sites.  For both the
          non-agncultural Pathway 10, the HEI is a small insectivorous mammal
                                  organisms-
         Methods
                                                                                    in Section
                                                                                 incorporation
                                                 4-41

-------
  of land-applied sewage sludge.  This implies that the soil layer to which the soil-dwelling
  organisms are exposed is pure sewage sludge.  Therefore, the concentration of each pollutant
  in the exposure layer ("soil")  is set equal to its concentration in the sewage sludge.

        Exposure for Pathway 10 is reported in terms of milligrams pollutant per kilogram of diet
  for the insectivorous mammal, assuming that the only source of the pollutant hi the mammal's
  diet is from ingestion of contaminated soil-dwelling organisms (eaVthworms).  This dietary
  concentration is referred to as the "pollutant intake level" and is represented by P/Ly hi the
  following equation:
                            EXPAj = PILj. = CTj' BACCj • FD                    (4-13)
                     =     exposure of insectivorous mammal to pollutant j (mg pollutant/kg
                            diet>>
                     =     intake  level  of pollutant  j in  insectivorous mammal's  diet
                            (mg pollutant/kg diet),
                     =     concentration. of pollutant j  in  sewage sludge-amended  soil
                            (mg pollutant/kg sewage sludge-amended soil),
        BACCj       =     bioaceumulation  factor  for pollutant j  (mg  pollutant/kg  soil
                            organisms per mg pollutant/kg sewage sludge-amended soil), and
        FD           =     fraction of diet considered to be soil organisms (unitless, kg soil
                            organisms/kg diet).

        First,  the concentration of the pollutant in the soil-dwelling prey is calculated by
 multiplying the pollutant concentration hi the  soil (CTJ) by a bioaceumulation factor (BACC).
 To adjust the pollutant concentration hi soil-dwelling organisms to the analogous concentration
 in the entire diet of the insectivorous mammal, the concentration hi the soil-dwelling organisms
 is then multiplied by the fraction of  the  insectivorous mammal's  diet that consists of soil-
 dwelling organisms.                                              "             .       •

 Data Inputs

       There are two data inputs required for this pathway: fraction of diet considered to be
 soil organisms and bioaceumulation factors. As in. Round One, it is assumed that the fraction
 of  the  HEI's  diet  that is composed  of' soil-dwelling organisms  is  one-third,  based on a
 consideration of maximum chronic consumption of earthworms by wildlife (U.S. EPA, 1992a).

       Because earthworms are generally the most conspicuous prey item of the soil biota and
are considered a potential vector for the transfer of sewage sludge pollutants up the food chain,
a number of studies have measured bioaceumulation  hi earthworms.   Most of the studies,'
however, have been focused on a select set of metals (e.g., cadmium, lead, mercury, selenium!
zinc, copper, nickel, and chromium) or persistent chlorinated hydrocarbons, such as DDT (see
Beyer, 1990; Gfflett,  1994).  Very few data were found on bioaceumulation of Round Two
candidate pollutants by earthworms from soil.
                                         4-42

-------
         Bioaccumulation  of  Organic  Pollutants.    No  empirical  data were found  on
  bioaccumulation in soil organisms for any of the candidate organic pollutants for Round Two
  except dioxins and dibenzofurans.  A predictive equation that describes bioaccumulation of all
  organic compounds  hi earthworms inhabiting contaminated soils  was found (Menzie  et al
  1992). This equation is based on a relationship between the fraction of organic carbon in the
  soil and the lipid content of earthworms:                          .


                                  •  BACC = -	-	
                                             0-66  •/«

  where:                                   .
        BACC =     bioaccumulation factor for earthworms (dimensionless),
        YI     =     Hpid content of earthworms (fraction),
        0.66   -     constant derived by Menzie et al., 1992, and
        fac     =     the fraction of organic carbon in the mixing zone of the sewage sludge-
                     amended soil.

 The lipid content of earthworms can be assumed to be two percent, as reported in Menzie et al
 (1992) for the earthworm Lumbricus terrestris.  Assuming the fraction of organic carbon in the
 mixing zone of  the  sewage  sludge-amended  soil  to be 0.01  (U.S.  EPA   1992a)  the
 bioaccumulation factor in earthworms for all organic  pollutants would be 3.0.  This value was
 not used hi Round Two, however, because it is not pollutant-specific.

        Bioaccumulation of Inorganic Pollutants. Very few studies were found  from which
 bioaccumulation factors for the inorganic Round Two candidate pollutants could be  determined
 Walton (1987) investigated sodium fluoride accumulation in earthworms (primarily Lumbricus
 terrestris).  From the results of one of the experiments, the bioaccumulation factor for worms
 (including gut contents) in soil with a high level of fluoride was calculated to be 0 670  This
 value was used for the BACC for fluoride.

       Helmke  et  al. (1979)  investigated  effects  of land-applied sewage sludge on the
 concentration of many different elements in earthworms (Aporrectodea tuberculata) Four of
 the elements measured were candidate Round Two pollutants: antimony, barium, manganese
 and thallium.  By taking the ratio of the reported concentrations of these metals in earthworms
 living in the control soil to the concentrations of the  metals in the control soil, BACCs were
 calculated for antimony, barium,  manganese,  and thallium.    The authors noted that the
 earthworms  may not  have  truly accumulated  these metals into their tissues.  Instead  the
 concentrations measured were probably due to the metals in the casts (soil in the gut of the
 worms). However, because predators of earthworms eat entire  earthworms, including casts
Aese bioaccumulation values were  considered appropriate for  this analysis.   Exhibit 4-15
displays the  bioaccumulation factors used for the candidate Round Two pollutants.  Note that
it pollutants  do not have data on bioaccumulation, they are not included in the exhibit
                                        4-43

-------
                                     EXHIBIT 4-15
                  Bioaccuinulation Factors for Soil-Dwelling Organisms
Pollutant
J=— - •- • • 	 - ----- - - - - "
Antimony
Barium
Dioxins and Dibenzofurans
Fluoride
Manganese
Thallium
-• • - ~ 	 	 -^•^=^r=^=
Bioaccumulation Factor
0.13
0.062
10
0.67
0.073
0.062
,!.
Reference
Helmke et al. (1979)
Helmke et al. (1979)
U.S. EPA (1994a)
Walton (1987)
Helmke et al. (1979)
Helmke et al. (1979) .
 Example Exposure Calculation for Pathway 10

       The following example estimates exposure of predators of soil-dwelling organisms to
 manganese in agricultural soil.                                   .                 •    -
Eq. 4-2:
       First, the mass of soil in the mixing zone, MS, is estimated for agricultural land by using
where:
              MS =  1600*g •  I5cm .  W^Mg/ha  _ 2400Mg
                      J"3            kg ' cm/m3       ha


1600   =     BDsoil (bulk density of soil) from Exhibit 4-3,
1 *\     -—     j /-a-»_-.i_ _^ ?	     .•   .     '
       15
       10:1
                                      -,
d (depth of incorporation for agricultural land) from Exhibit 4-3 and
constant to convert (kg • cm/m3) to (Mg/ha).
      The concentration of manganese hi the soil is then calculated using Eq. 4-1:
                                       4-44

-------
                 manganese
                           f342mg . 2400Afg\ + f     <  1620wg ,  7Mg
                                            ha-yr)    .  ha


                        = 410mg/kg
  where:
         .
        342  . =    flSy (background concentration of manganese in soil) from Exhibit 4-4,
        2400  =    MS (mass of soil hi agricultural mixing zone), estimated above,
        20    =    N (total number of years sewage sludge is  applied to agricultural land)
                    from Exhibit 4-3,
        1620  =    Cj (manganese concentration hi sewage sludge) from Exhibit 4-1, and
        7     =    AR (application rate of sewage sludge to agricultural land) fron/Exhibit
       Hie "pollutant intake level" (PZL), and thus exposure of the HEI, is then calculated using
                                                  "
    . *T~ 1 3 I
                                                       • 0.073 '
                                                   kg           3
                                      = 10 mg/kg

 where:     -
       n1*™  I     ^ (concentration of manganese in agricultural soil), estimated above,
       0.073  -     &4CCy(bioaccumulation factor for manganese for soil-dwelling organisms)
                    from Exhibit 4-15, and
       1/3     =     FD (fraction of diet that is soil-dwelling organisms), discussed above.


 4.2.11 Pathway 11 - Human Toxicity Through Inhalation of Particulates Resuspended by
             Tilling Sewage Sludge

       Pathway 11 evaluates human (tractor operator) exposure to particles that have been
 resuspended by the tilling  of dewatered sewage sludge into the soil.   Because this type of

                                     exposure to -"* sludge ^^ to
Methods

      To ^Iculate uie total poUutant concentration in the soil for both organics and inorganics

                           ' T° ^
                                       4-45

-------
                                EXPTj = CTj • TDA - IV*     '                   (4-14)


   where:

              j  =     exposure of tractor operator to pollutant j (mg pollutant/m3 air),
                                                                              ,
                      concentration   of  pollutant   j  in  sewage   sludge-amended   soil
                      (mg pollutant/kg sewage sludge-amended soil),
         TDA  =     total exposure of tractor operator to soil dust (mg soil dust/m3 air)  and
         10"*   =     constant to convert (kg) to (mg).

  Data Inputs


        As in Round One, the total dust exposure of the tractor operator is assumed to be the
  total dust standard of 10 mg/m3 established by the  American Conference of Governmental
  Industrial Hygienists (ACGIH).            '                                wvcnamanai


  Example Exposure Calculation for Pathway 11


        The following example estimates exposure of a tractor operator to manganese.


                 maSS °f S0il m ^ mixillS zone' M5' is estimated for agricultural land by using
                     MS =  1GOOkg -  15cin . W~lMg/ha =  2400Mg
                             m3            kg • cm/m3      ha
 where:

       1600  =    BDsoil (bulk density of soil) from Exhibit 4-3,
15     =

                    d (depth of incorporation for agricultural land) from Exhibit 4-3 and
              =     constant to convert (kg • cm/m3) to (Mg/ha).



       The concentration of manganese in the soil is then calculated using Eq. 4-1:
                          (342^ .  2400Mg\ + /     .  1620mg  .  7Mg

                          Ljfe	*«   I   (^	kg	ha-yr
where:
                                    [2Qyr  - J!&-}  + 24QQ^
                                    {       ha-yr)       ha

                         410mg/kg
                                  concentration of manganese in soil) from Exhibit 4-4
                   MS (mass of soil in agricultural mixing zone), estimated above,
                                       4-46

-------
       20     =    N (total number of years sewage sludge is applied to agricultural land)-
                    from Exhibit 4-3,
       1620  =    Cj (manganese concentration in sewage sludge) from Exhibit 4-1, and
       7      =    AR (application rate of sewage sludge to agricultural land) from Exhibit 4-
                    3.   •         •                                                  •

       Using Eq. 4-14, exposure of the tractor operator to manganese is then estimated as:
                                               • 10     • !()•«-
                                            g     m3       mg


                                    = 4.b:10-3 mg/m3

where:                         •
       410   =     CTj (concentration of manganese in agricultural soil), estimated above.
       10    =     TDA (total exposure of tractor operator to soil dust), discussed above, and
       10'6   =     constant to convert (kg) to (mg).
                                        4-47

-------
  4.2.12       Pathway 12 - Ingestion of Fish and Water from Surface Water that Receives
               Eroded Soil

         Pathway 12 evaluates human ingestion of fish and water from surface water that receives
  eroded soil  from  sewage sludge-amended agricultural  and non-agricultural lands.   Non-
  agricultural lands include forests, reclamation sites, and public contact sites.

         To estimate exposure for this pathway,  a mass balance analysis is required.  This mass
  balance analysis accounts for the partitioning of pollutants into different soil phases (solids, air,
  and water) and the subsequent losses of pollutants from the land application site.  Pollutants are
  lost from a land application site by: erosion of soil particles, which releases sorbed pollutants
  into surface waters; volatilization of pollutants into air; leaching of pollutants into groundwater;
  and degradation.  A mass balance for a pollutant must be maintained, given these four competing
  loss processes of erosion,  volatilization, leaching, and  degradation.  Once  mass balances for
  pollutants have been established, exposures to pollutants that have  eroded, volatilized, or leached
  are calculated under three separate pathways: surface water (Pathway 12),  air  (Pathway 13), and
  groundwater  (Pathway 14). It is assumed that if pollutants degrade, they degrade into chemicals
  that do not pose unacceptable risks  to public health or the environment.

        The methods for performing the mass balance  calculation for Pathways 12, 13, and 14
 are discussed below. Subsequent to this discussion, the equations particular to Pathway 12, for
 estimating the maximum amount of pollutant available for erosion at a site and the transport of
 that pollutant mass to a surface water stream, are presented.

 Method for Mass Balance (Pathways 12,  13,  and 14)

        There  are two major steps involved  in the mass balance calculation.  First, a pollutant
 is partitioned  among the three phases present hi a soil:  solids, air, and water.  Second, the rates
 at which the four loss  processes occur (erosion, volatilization, leaching,  and degradation) are
 estimated.   These .two steps are described in the next two subsections.

        Step 1: Partitioning of Pollutant Among Solids, Air, and Water in Sewage Sludge-
 Amended  Soil.  This  section describes the  methods for  partitioning a pollutant in the sewage
 sludge-amended soil at a  land application site, assuming  that equilibrium  is maintained among
 the pollutant concentration  sorbed onto soil particles  (which erodes into surface water), the
 pollutant concentration in  the  air-filled pore  space  (which volatilizes), and the pollutant
 concentration  in the  porewater (which leaches to groundwater).

       Equilibrium partitioning between sorbed and dissolved phases is described by soil-water
partition coefficients; partitioning between dissolved and gaseous phases is described by Henry's
Law constants. From these assumptions and the definitions of concentrations in different phases
presented below, equations are derived to describe pollutant partitioning among all of the phases.
                                          4-48

-------
  Mathematically, pollutant concentrations in different phases can be expressed as:
                            C  =
                                  Ms
                                    s
  and:


                                C{  = ~f  =   V 1  V^r   ^                       (4"16)

  where:      .
         C,      =     concentration of sorbed pollutant .on sewage sludge-amended soil particles
                      (kg pollutant/kg soil),
        Mcs     =     mass of sorbed pollutant (kg),
        M-s      =     mass of soil (kg),
         Vs      =     volume of solids in soil (m3),
        Ca      =     concentration of gaseous pollutant in  air-filled pore space  of sewage
                      sludge-amended soil (kg pollutant/m3 air),
        Mia     =     mass of gaseous, pollutant (kg),
        Va      =     volume of air in soil (m3),
        Cu.      =     concentration of dissolved pollutant in water-filled pore space of sewage
                      sludge-amended soil  (kg pollutant/m3 porewater),
        Mm.    =     mass of dissolved pollutant (kg),
        K     =     volume of water in soil (m3),
        C,     =     total concentration of pollutant in bulk  sewage sludge-amended soil (kg
                      pollutant/m3 total bulk soil volume),
        Ma     =     total mass of pollutant in soil (kg),  and
        V,      =     total bulk volume of soil (m3).


        The definitions of equilibrium partition coefficients and soil characteristics, such as bulk
density and porosity, are used in conjunction with Eqs. 4-15 and 4-16 to estimate the pollutant
concentrations  in each  soil  phase  (solids, air, and water).   The equilibrium partition  or
distribution coefficient (Kd), describing the  partitioning of a pollutant between pollutant sorbed
on solids and pollutant dissolved in  porewater, can be defined as:
                                                                                   (4-17)

where:
       Kd     =      soil-water partition coefficient (L water/kg soil), and
       103    =      constant to convert (m3) to (L).
                                          4-49

-------
          The dimensionless Henry's Law constant, which describes the partitioning of a pollutant
   between gaseous and dissolved phases, is defined as:
                                                  = ,.   _.                          (4-18)
                                        l*"cw/ r *J    Me* Va
  where:
         H     =     Henry's Law constant (dimensionless).

         The bulk density of soil is defined as:

                                             = MJ Vt                             (4-19)

  where:              •                                                              .
        #Anir   =     bulk density  of sewage sludge-amended soil (kg soil/m3 total bulk soil
                      volume).

  The air-filled porosity of soil is defined as:                   .                       •     -

                                        0C = va I Vt                               (4-20)
 where:                                                       .
        ^a     =     air-filled porosity (dimensionless).

 The water-filled porosity is defined as:

                                       ew =  rw/*V                              (4-21)
 where:
       0W    =     water-fmed porosity (dimensionless).

 And, the total porosity of soil is defined as:

                               *     *    S     t     O    W                       \  ™<«'^' t
 where:      .                                                                             .
       ^t      —     total soil porosity (dimensionless).

By combining Eqs. 4-15 through 4-22, equations that describe the pollutant concentrations in the
air and water phases in terms  of the  total pollutant concentration can be derivS:

                                          4-50

-------
                             c  .	s	    •     •
                              a    Kd BDmiI     _3    6M.                           (4-23)
                                   ~~5       x    +1+ 6a
 and:
                            Cw  = - - - - ^— - —                   (4-24)
                                                '
                                        Kd • ID
        Equations 4-23  and  4-24 are  used to estimate the  first-order rate constants for
 volatilization and leaching in the second step of. the mass balance calculation.

        It is important to note that in these derivations, Cr, the total pollutant concentration in
 sewage sludge-amended  soil, is expressed as  mass per volume.  Recall that in Pathways 1
 through 1 1 , the total pollutant concentration is expressed as mass per mass of soil (CTJ).  These
 two quantities can be related through the following equation:
                                 Ct  =  CTj • BD^ • 1
-------
                               Ku><  = *m + *„, + KUC + K*8                      (4-26)

  where:
         KM    =     total loss rate for.the pollutant from sewage sludge-amended land (yr1),
         Kcro    *=     loss rate due to erosion of the pollutant from sewage sludge-amended land
         K^i    -     loss rate due to volatilization of the pollutant from sewage sludge-amended
                      land (yr1),              .
         K&    -     loss rate due to leaching of the pollutant from sewage sludge-amended
                      land (yr1), and        .
         K
-------
   where:

         dt     =     average rate of soil loss due to erosion from sewage sludge-amended land
                       each year (m/yr),
         d      ~     dePtih of incorporation of sewage sludge (cm), and
         10'2    =     constant to convert (cm) to (m).

         Note that this assumes that the loss to erosion includes pollutant mass in all three phases
  (solids, air, and  water); therefore, the first-order loss coefficient is not pollutant-specific   That
  is, given the assumption of even incorporation, if one-tenth of the sewage sludge-soil mixture
  is removed by erosion, one-tenth of the mass of pollutant is also removed.

        First-Order Loss  Rate for  Volatilization.   Estimates  of volatile  emissions  from
  uncovered soil are used in conjunction with estimates of pollutant concentrations in the air-filled
  pore space of soil to estimate the loss rate coefficient for volatilization, Kml.

  ,i«o^ ?timates of volatile emissions are based on equations provided by Hwang and Falco
  (1986) for contaminated soil  with no cover:


                                           2te6eD  C
                                    Na       —-I *                             (4-29)

 where:                                                .      '
       Na     =     total  average emissions  from the  soil  surface  over time interval  t
                     (kg pollutant/m2 soil),                                              f
       le      —     duration of emissions (sec),
       6e      =     effective porosity of soil (dimensionless),
       Dei     =     intermediate diffusivity variable (defined in Eq. 4-30) (nrVsec),
       Q      =     concentration of gaseous pollutant in air-filled pore  space of sewage
                     sludge-amended soil  (kg pollutant/m3 ah-), and
       a-,     =     intermediate diffusivity variable (defined in Eq. 4-31) (m2/sec).


In Hwang  and  Falco (1986), C9 is  estimated from the concentration of sorbed pollutant (C)
However  this analysis requires the relationship between the total concentration of pollutant *in
sewage sludge-amended soil (in sorbed,  gaseous,  and dissolved phases) and the concentration
m gaseous phase within the soil's air-filled pore space. Therefore,  Eq. 4-23 is used ^e*
foil™-™6 1interm;;dia* diffusivity variables required in Eq.  4-29  are  obtained  from the
following relationships (Hwang and Falco, 1986):
                                          4-53

-------
  and:
                                     Dei =
                                                              (4-30)
 and:
       ««=
                                                    Kd'io-3/H
                                                                                  (4-31)
  where:
                                                                                  (4-32)
 and where:
       H
       T
       lO'3
                                               H
                                          R • r •  10
                                                    -3
                                                                                  (4-33)
the molecular diffusivity of pollutant in air (cm2/sec),
constant to convert units fronv(cm2) to (m2),
effective porosity of soil (dimensionless),
particle density of sewage sludge-soil mixture (kg/m3),
soil-water partition coefficient (L water/kg soil),
Henry's Law constant (dimensionless),
bulk density of sewage sludge-amended soil (kg soil/m3 total bulk soil
volume),
total soil porosity (dimensionless),
Henry's Law constant (atm-m3/mol),
gas constant (L-atm/mol-K),
temperature (Kelvin), and
constant to convert. (L) to (m3).
       Equation 4-29 provides an estimate of total average emissions from an uncovered layer
of soil as a function of both time and the initial concentration of pollutant. For consistency with
methods used to estimate losses for other pathways, Eq. 4-29 is evaluated for te equal to 1 year
(r^3.2x!07 sec), and results are used to estimate an annual loss coefficient.  Losses predicted
for the first year (Afap are divided  by the total mass of pollutant hi soil to  estimate the
approximate  fraction of available pollutant lost per unit of time. For a unit concentration (1
kg/m) of the pollutant hi soil (i.e., Q, the mass of pollutant beneath one square meter of soil
surface (in kg/m2) is equal to the volume of treated soil beneath a square meter of surface (m3
                                          4-54

-------
   per nr), that is, equal to the depth of incorporation (m).  The estimated loss rate (in kg/nr-yr)
   is approximated as a comparable first-order loss, coefficient (in yr1) as:


            .                                 /     Na   \
                                   K^  *  -In 1-	Jl_                   ,  .      (4-34)
                                             I  d • 10-2J                    .

   where:
         K^    =     loss rate due to volatilization (yr1),
         Nay    =     total   average   emissions  from   the   soil   surface  in   first   year
                      (kg pollutant/m2),  estimated using Eq. 4-29,
         d      =     depth of incorporation of sewage sludge (cm.  When converted to  (m),
                      equivalent to kg/m2 for a unit concentration of pollutant hi sewage sludge-
                      amended soil), and
         10'2    =     constant to convert (cm) to (m).

  Because Eq. 4-29 was derived by assuming the column of soil is of infinite depth  it can predict
  greater than 100 percent loss within a year for a relatively shallow layer of treated soil and a
  relatively volatile pollutant.  For such cases, Eq. 4-34 cannot be evaluated and the loss  rate
  coefficient is instead estimated from predicted emissions in the first second (t = 1 sec)  The loss
  rate coefficient estimated from the first second of emissions is then converted to an annual  loss
  rate coefficient:
                              K^ *  -3.2xl07lnfl-  Na'.  }                      (4-35)
                                                (   d-W2)   .

 where:                            .
      . Na*          =     emissions from the soil surface in first second (kg pollutant/m2)
                            estimated using Eq. 4-29,
       3.2xl07       =     constant to convert (sec'1) to (yr1), and
       10~2          -     constant to convert (cm) to (m).


   '    Equation  4-34 was used to evaluate carbon  disulfide,  dioxins  and  dibenzofurans
endosulfan, pentachloronitrobenzene, PCBs, and  2-(2,4,5-trichloroPhenoxy)  propionic acid
However, for the other Round Two pollutants that volatilize, Eq. 4-35 was used.

       First-Order  Loss Rate  for Leaching.  To estimate pollutant loss  to leaching  the
fo owing Aquation  which computes a first-order loss rate for a pollutant leaching from treated
soil (US. EPA,  1989f), was modified to take into account that leaching is only one of four
competing pollutant loss processes:
                                         4-55

-------
                                               NR
                                           Kd
 where:
        K&    ==     loss rate due to leaching of the pollutant from sewage sludge-amended
                     land (yr1),                 .     .
        NR    =     annual recharge to groundwater beneath the treated soil (m3 recharge/m2
                     area-yr, or m recharge/yr),
        BDma '  =     bulk density of sewage sludge-amended soil (kg ,soil/m3  total  bulk  soil
                     volume),
        Kd     =     soil-water partition coefficient (L water/kg soil),
        d      =     depth of incorporation of sewage sludge (cm),  .
        10'3    =     constant to convert (L) to (m3), and
        10"2    =     constant to convert (cm) to (m).

        To derive a coefficient for first-order loss to leaching while maintaining a mass balance,
 the mass of pollutant expected to be lost each year is estimated and divided by the available mass
 of pollutant. The mass of pollutant that will be lost to leaching in any interval of time per unit
 area (i.e., the flux of pollutant) can be described by the volume of water percolating through the
 treated soil multiplied by the average concentration of pollutant in that water:          •     -


                            .    FAUc  = NR • CUc • 10,000                         (4-37)

 where:         '                       ,
       FA,ec          =     annual average flux  of pollutant leached  from sewage sludge-
                           amended soil (kg pollutant/ha-yr),
       Ore           =     concentration of pollutant in water leaching from sewage sludge-
                           amended soil (kg pollutant/m3 porewater), and
       10,000        =     constant  to  convert units from (kg/m2-yr) to (kg/ha-yr).


       Assuming that all  the porewater forms leachate, Eq. 4-24 can be used to estimate the
pollutant concentration in the leachate:              .
                      C"^°>>^-ie.^ej

where:
       CH.     =     concentration of dissolved pollutant in water-filled pore space of sewage
                    sludge-amended soil (kg pollutant/m3 porewater),
    '   Q      =     total  concentration of  pollutant in bulk sewage sludge-amended  soil
                    (kg pollutant/m3 total bulk soil volume),
       0W      =     water-filled porosity (dimensionless),
                                          4-56

-------
         H     =     Henry's Law constant (dimensionless),
      .   0a     =     air-filled porosity (dimensionless), and
         10'3    =     constant to convert (L) to (m3).


  Given that first-order loss rates are being assumed, the total concentration of pollutant in soil
  decreases due to leaching according to the following equation:
                                       dC

                                       ~dt
1 = ~KUcCt                              (4-39)
 KUc can be estimated with the discrete approximation:
                                ».;   — ——  — •   '  = >    I                       i~r~*T\))
                                       f      f       \g
                                       ui      <-,      Az_      r
 where:
        t       —     time (yr).
 The change in the total pollutant mass in the soil with time can be expressed in terms of the
 pollutant flux leaching to the groundwater:


                                 AM"
                                 	^*  ^  ^y A     A   « f\'*&                  '        / A  A •< \
                               --£-  -^fa'^ -10-4                          (4-41)


 where:                                                                                .

       A34/A/       =     change in total mass of poUutant in soil over time interval of one
                           year(kg/yr),
       A             —    • area of land application site (m2), and
       10^           =     constant to convert units from (m2) to (ha).


Combining Eqs. 4-40 and 4-41:


                                            .  • A  - ID"4
                                            -r;	                    '      (4-42)
                                         4-57

-------
  Given that the total bulk volume of sewage sludge-amended soil equals the area of the land
  application site multiplied by the depth of incorporation:


                                    Vt = A  • d •  1(T2

  where:
        Vt     =     total bulk volume of soil (m3),

  and rearranging Eq. 4-16:
 the following equation can be written:
 Using Eqs. 4-37, 4-38, and 4-43, Eq. 4-42 can be rewritten as:
                         NRCu<   _                NR
                                                                               (A-AA\
                                                                               (    '
                                        Vmix'Kd* QW  + & Oj d • ID'2


 Equation 4-44 is used to predict the rate of pollutant loss to leaching.   -


       First-Order Loss Rate for Degradation. Values of K^ are obtained from the literature
 for each pollutant. For K^, rates of abiotic reactions such as hydrolysis are preferentially used
 because  they can be more reliably measured; for pollutants only degraded by microbes,  the
 lowest aerobic rates measured under environmental conditions are used.  For inorganics' and
 some persistent organic pollutants such as dioxins and dibenzofurans,  K^. is zero.

 Methods Specific to Pathway 12

       Overview of Methods Specific to Pathway 12. To calculate the average concentration
 of a pollutant in eroding soil, estimates of the maximum mass of pollutant available for erosion
 from a land application site are combined with estimates of the rate at which the pollutant is lost
 from the site due to the four loss processes.over a human lifetime.  The average concentration
 of pollutant in eroded, sewage sludge-amended soil is then "diluted"  by the erosion of clean soil
 from the remainder of the watershed.  Estimates of the concentration of pollutants in the stream
receiving the eroded soil are then made, derived from the mass of pollutant on eroded soil and
                                         4-58

-------
  on soil- water partition coefficients.  Pollutants then partition into fish inhabiting the stream.
  Humans are exposed to pollutants through both direct ingestion of surface water and ingestion
  of fish. For this analysis, organics as well as inorganics are allowed to build up in the soil over
  the active life of the land application site.

        Maximum Pollutant Mass Available for Erosion.  The maximum mass of pollutant
  available for erosion at a land application site occurs after the final application of sewage sludge
  to the site. This maximum mass is estimated as:


              TPN  = AR • Cj  • (\+e~c'Ka*+e~*c.'K**+...+e~b' *'***) • 1000  • 1       (4-45)

 where:
        TPN   =    total mass of pollutant available at a site after the final year of application
                    (mg pollutant/ha),                     .
       AR    =    annual whole sludge application rate of sewage sludge to land (dry Mg
                    sewage sludge/ha-yr),
        Cj     =    concentration of pollutant j in sewage sludge (mg pollutant/kg sewage
                    sludge),
       c     =    application interval (number of years between applications),
       Ktot    =    total loss  rate for the pollutant from sewage sludge-amended land (yr1),
       b     =    model parameter that is equal to the integer part of ((^te-l)/c), where N ~
                    is the site life (yr),                                 ..        •     «*
       1000   =    constant to convert (Mg) to (kg), and
       1      =•    interval of time over which pollutant loss is evaluated (yr).


       Losses to Erosion Averaged Over a Human Lifetime.  Because human exposure is
assumed to continue for the duration of an individual's lifetime, concentrations of pollutants in
surface  water  are calculated based on losses of pollutant through surface erosion for a period
equal to  the human life expectancy. Therefore, loss to erosion during the period between the
end of land application  and the end of an individual's lifetime must be estimated. To do so  the
mass of  pollutant left at the end  of an individual  lifetime is first calculated.  After the' last
application of sewage sludge to a site, a pollutant continues to be depleted according to the
following equation:
                               MLS = TPN •e~*-V*~ir"''>                         (4-46)

where:
      MU   =     mass of pollutant in soil at end of a period equal to an individual lifetime
                    (mg pollutant/ha),
      LS    =     average human lifetime (yr), and
      Nsiu   =     site life (yr).
                                         4-59

-------
         The fraction of total, cumulative loading lost to all four loss processes in the human
   lifetime (over both the application and post-application periods) can then be calculated as:
                     frs =
  where:
                                            ' AR ' 100°)  "
                                        N  • C, • AR '• 1000
                                                                                   (4-47)
JLS
                      fraction of total cumulative loading lost in individual's lifetime to all four
                      loss processes (dimensionless).                   .
         This fraction is used'to estimate the average pollutant concentration in eroded soil for
  both organic and inorganic pollutants.  The estimated total loading of pollutant is multiplied by
  the fraction expected to be  lost to erosion in the human lifetime (f^ -/^), and divided by the
  total mass of eroded soil lost during that period to calculate the expected average concentration
  of each pollutant in eroded  soil:
 where:
         •"me. j
        ME,.
                           "site, j
                                                             ILS
                                                                          (4-48)
                    the concentration of pollutant j in sewage sludge-amended soil
                    eroded from the land application  site (mg pollutant/kg  sewage
                    sludge-amended soil),
                    rate of soil loss for land treated with  sewage sludge (kg  sewage
                    sludge-amended soil/ha-yr), and
 where:
       BD.
       10,000
                                                   '10,000
                                                                         (4-49)
                   average rate of soil loss due  to  erosion  from sewage sludge-
                   amended land each year (m/yr),
                   bulk density of sewage sludge-amended soil (kg soil/m3 total bulk
                   soil volume), and
                   constant to convert (m2) to (ha).
Note that Eq. 4-48 assumes that the same mass of pollutant leaves the site by erosion every year.

       Dilution of Eroded, Sewage Sludge-Amended Soil with Non-Sewage Sludge-Amended
Soil.  The extent to which eroded soil from the land application site is  "diluted" by soil from
the untreated remainder of the  watershed also needs  to be estimated.   A "dilution factor"
                                          4-60

-------
  describes the fraction of the total eroded soil in the watershed originating in the land application
  site:
  where:
        Df     =     dilution factor (dimensionless),
        Asite    =     area of land application site (ha),
        Aws     =     area of the watershed (ha),
        Ssite     =     sediment delivery ratio for the land application site (dimensionless),
        Sws     =     sediment delivery ratio for the watershed (dimensionless), and
        ME**   -     estimated rate of soil loss (erosion) for the watershed (kg soil/ha-yr).


 If the rates of soil erosion from the land application site and the remainder of the watershed are
 assumed to be the same, ME!ite and MEWS cancel from Eq. 4-50, and the dilution factor can be
 calculated by:
                               Df =	:


        The sediment delivery ratios for the land application site arid the watershed are calculated
 with the following empirical relationship (Vanoni, 1975):


                                     S = 0.872 A-*135


Thus, the sediment delivery ratio for the site and for the watershed are:


                                  S^ =  0.872 [A^-*-125                           (4-52)


and
                                      = 0.872 HJ-0'125                           (4-53)
                                          4-61

-------
         If all of a pollutant entering the stream on eroded soil is assumed to originate from the    •»
  land application  site, the  dilution factor, Df,  also describes  the  ratio between the average    ^^
  concentration  of  pollutant hi  soil entering the stream and the average concentration in soil
  eroding from the  land application site:


                                     C.      = D  • C"                                (4,-^£\
                                      esoil,j    ^f    site,j                            (,t*-Jtt)

  where:
                          weight concentration of pollutant/ in eroded soil entering the stream
                      (mg pollutant/kg eroded soil).


        Pollutant Concentration in the Stream.  The estimated concentration of pollutant in the
 eroded soil is used as an input to calculate the expected concentration of pollutant in the stream.
 Once the eroded soil enters the stream, the pollutant is assumed to partition between the solid
 and liquid phases of the stream according to equilibrium conditions.   The total amount of
 pollutant available.to partition depends on the amount of eroded soil in the stream.  Assuming
 that all of the  total suspended solids  in the stream are from eroded  soil particles, Eq. 4-55
 partitions the total mass of pollutant between dissolved and sorbed phases.  The  lefthand term
 represents the total mass of pollutant (per liter of water) entering the stream hi eroded soil; the
 middle term represents the dissolved pollutant; and, the right-most term represents the mass of
 sorbed pollutant (per liter of water):
                                  10"6  = 
-------
                                       *<-*<*;/«<                              (4'57)

  where:
         Koc     =     organic carbon-water partition coefficient (mL water/g organic carbon),
                      and                          v .
        f^     =     fraction of organic carbon in suspended solids (dimensionless, g organic
                      carbon/g suspended solids).

                    *
  A value of 0.01 is used for the .4 of suspended solids,  to correspond to the .4 of -the mixing
  zone from which the suspended solids are assumed to have eroded (U.S. EPA, 1993a)

        To estimate an organic pollutant's Kx value, an empirical regression equation presented
  by Hasset et al. (1983) is used:
                           loSio(*oc) ".0.088 ' + 0.909 log^^)                   (4-58)

 where:
        K^    =     octanol-water partition coefficient (dimensionless, mg pollutant/L octanol
                     per mg pollutant/L water).


        Partition Coefficients for Inorganic Pollutants.  For inorganic pollutants, it is much
 more difficult to predict a "typical" Kd value.  Metals can sorb onto soils through the processes
 of ion exchange, specific adsorption, co-precipitation with hydrous oxides, and incorporation into
 canonic lattice sites in  crystalline sediments (Bodek et al., 1988).  Therefore, clay minerals
 organic  matter, and manganese and  iron oxides  are .all important sorbents of metals in soil
 (Bodek et al.  1988).   The pH of the system also  affects metal sorption, with most metals
 tending to sorb more at higher pHs.  Therefore, measured Kd values reported in  the literature
 tor conditions similar to those being modeled are used.

 Estimating Human Exposure

       Humans can be exposed to surface water contaminated by sewage sludge through two
 pathways:  ingestion of water and  ingestion  of fish.  Potential exposure through ingestion of .
 contaminated surface water is calculated as:                                      s^uuu "i
                                                                                (4-59)
                                               on

where:
                           exposure to pollutant j through direct ingestion of surface water
                           (mg pollutant/kg body weight-day),
                                         4-63

-------
         Cwj         =     concentration   of   pollutant  j   in    surface   water
                             (mg pollutant/L water),
         IW          =     quantity of water ingested daily (L water/day), and
         BW          =     body weight (kg), assumed to be 70 kg.


         Exposure through ingestion of fish is calculated based on estimates of the bioaccumulation
  of a pollutant in fish and the assumed rate of fish ingestion.  Bioaccumulation is the process by
  which aquatic organisms accumulate pollutants, from both water and food, at concentrations
  higher than the ambient concentration.  The process by which a pollutant is absorbed from water
  through gill membranes or other external body surfaces is called bioconcentration, and the
  measure of a pollutant's tendency to bioconcentrate is described by the bioconcentration factor.
  For organic pollutants,  a regression equation based on logCK^) values is used to estimate
  bioconcentration factors (BCFs).  The equation was developed for a three percent limd content
  of fish (U.S. EPA, 1990):                                                    H
                            log10(£CP) = 0.79 log^*^ - 0.80                   (4-60)

 where:
        BCF   —     pollutant-specific bioconcentration factor (L water/kg fish).


        For inorganic pollutants, available literature values were used for BCFs.

        Biomagnification denotes the process by which the concentration of a pollutant increases
 hi different organisms occupying successive trophic levels.  The combined accumulation from
 bioconcentration and biomagnification is represented by the bioaccumulation factor, which
 calculated as the product of the bioconcentration factor and a food chain multiplier: '
is
                                    BAF = BCF-FM                            (4-61)
                       r
 where:
       BAF   =     pollutant-specific bioaccumulation factor (L water/kg fish), and
       FM    =     pollutant-specific food chain multiplier (dimensionless).


       Assuming that humans  only  ingest fish fillets, and not the whole fish, the pollutant
concentration in fish fillets can be expressed as:
                                 CJKl  * c~j ' *** ' Pf                          (4-62)

where:                                                                     '
       CKJ    =     concentration of pollutant/ in fish fillets (mg pollutant/kg fish fillet), and


                                         4-64

-------
        •Pf     =     ratio of pollutant concentration in fillet to whole fish (dimensionless).


  Thus, human exposure through ingestion of contaminated fish can be expressed as:


                                    EXPf . =   ffJ'IF                             (4-63)
                                        fj      BW

  where:
     '   EXPf.j ~     exposure to pollutant/ through ingestion of fish (mg pollutant/kg body
                      weight-day), and
        IF    =     daily consumption of fish fillets (kg fish fillets/day).


        For this analysis of the surface water pathway, exposures through drinking water
 consumption  and fish ingestion are combined:
                                 EXPJ = EXPWJ + EXPfJ            .  .         .  (4-64)

 where':                                                                            .  .  _
        EXPj   =     exposure to pollutant/ through consumption of both surface water and fish
                     combined (mg pollutant/kg body weight-day).


 Data Inputs

        Both non-pollutant-specific and pollutant-specific inputs are required for the exposure
 equations described above.  Values for non-pollutant-specific inputs, such as the area of a
 watershed, its hydrogeological characteristics, and the daily consumption of fish and drinking
 water, are presented hi Exhibit 4-16.  Note that all parameters necessary for Pathways 12  13
 and 14 are presented in this Exhibit.

       There are several pollutant-specific fate and transport parameters required to maintain the
 mass balance of a pollutant among the four loss processes and to estimate the rates at that those
 four loss processes occur.   In Exhibit  4-17,  all of the fate and transport parameters  are
 presented.

       To obtain estimates of inorganic  Kd values for six Round  Two pollutants  studies  of
adsorption described in Gerritse et al. (1982) were used.  Gerritse et al. present a range  of Kd
values  for various inorganics in two soil types: sand and sandy loam.  In the sandy soil  there
was 0.035 g/g organic matter, 0 g/g clay, 0.22 meq/g cation exchange capacity (CEC), and the
porewater had a pH of 5.  In the sandy loam soil, there was 0.025 g/g organic matter, 0.2 g/g
clay, 0. 16 meq/g CEC, and the porewater had a pH of 8.  For this analysis, the Kd values from
sand, which were lower than those in sandy loam, were used.  In addition, the lowest Kd value
from the range available for each of the six Round Two inorganics  tested was used.

                                         4-65
•d

-------
        For aluminum and fluoride, available data on Langmuir isotherm parameters were used
  to estimate Kd values (Bodek et al., 1988).  For aluminum, data were for silica, at a pH of 5.
  For fluoride, data corresponded to clay loam, containing 10.4 percent clay, 0.94 percent organic
  carbon, and 825 /zg/g aluminum, with a pH of 5.9.  For boron, thallium, tin, and titanium, Kd
  values were not available.                                                   ' •      '

        In the absence of pollutant-specific data for the ratio of pollutant concentration in fillet
 to the concentration in whole fish, it is assumed that these concentrations are the same (Pf =  1)
 for all pollutants except PCBs and dioxins.  PCBs are assumed to behave similarly to dioxins,
 for which a ratio of 0.5 has been estimated (Branson et al., 1985).

        For BCF values for inorganic pollutants, the Ambient Aquatic Life Water Quality Criteria
 documents were reviewed.  Only three Round Two inorganics had such documents  available:
 aluminum, antimony, and silver. For aluminum, bibconcentration factors for young brook trout
 were reported to range from 50 to 231 (U.S. EPA, 1988a). The geometric mean (107) was used
 in this analysis. For  antimony, one study on bioconcentration in bluegill found no significant
 accumulation above controls (U.S. EPA, 1988b).  AQUIRE (Aquatic Toxicity  Information
 Retrieval) was then searched for BCF data on antimony.  The AQUIRE run turned up values for
 one saltwater fish and one fish that may  or may not be saltwater.  The BCFs for the shanny
 (Blennius pholis)  and for the  two-spot  goby (Gobiusculus flavescens) are  0.40 and. 0.15,
 respectively.  The geometric mean of these two values (0.24) was used in this analysis.  For
 silver, the Ambient Aquatic Life Water Quality Criteria for Silver document (U.S. EPA, 1987)
 had  BCF information  for two freshwater fish species, bass and bluegill.  The  geometric mean
 of the bass BCFs (11 and 19) is 14; the geometric mean of the bluegill BCFs (15 and 150) is 47.
 The geometric mean of the two species' BCFs is 26; this value was used in this analysis.

       AQUIRE was then searched for all  the remaining inorganics (Ba, Be, B, F, Mn, Th,  Sn
 Ti, and V).  No data on BCF values for freshwater fish were found.

       For FM values, if an organic pollutant had a log(Kow) value less than or equal to five, a
 value of one  was used;  otherwise a value of ten  was used for FM (U.S. EPA,  1990).  This
 relationship is applicable to a species on a trophic level of three.  For inorganic'pollutants  an
FM value of one was used.
                                        4-66

-------
                      EXHIBIT 4-16
Non-Pollutant-Specific Parameters for Pathways 12, 13, and 14
Parameter
LJ 	 : 	
r<
k
ra
K
•^site
II -^ws
jjc
U
1
" '
\\TSS
I
11

1 T
UF
\\IA
r-
1**
r
Definition
1 total soil porosity
effective soil porosity
air-filled porosity
water-filled porosity
area of land treated with
sewage sludge
area of watershed
application interval
yearly depth of soil eroded
annual recharge to
groundwater
density of water
total suspended solids in
surface water
angle subtended by the
land application site's
width
average wind velocity
vertical dispersion of
pollutant in air
average air temperature
daily consumption of fish
fillets
daily inhalation rate
daily ingestion of water
site life
]
gas constant <
|]
Value
— — ^—
0.4 (dimensionless)
0.4 (dimensionless)
0.2 (dimensionless)
0.2 (dimensionless)
1,074 ha
440,300 ha
varies
6 x 10-4 m/yr
0.5 m/yr.
1 kg/L
16 mg/L
22.5°
4.5 m/sec
1 (dimensionless)
288 Kelvin
0.04 kg/day
20m3/day
2 L/day
ZOyrag., forest,
sub., 1 yr reel.
3.082 L-atm/mol- •
Kelvin
	 1
Reference
4 — 	 1 	 = 	
U.S. EPA, 1992a
U.S. EPA. 1992a 1
U.S. EPA, 1992a 1
U.S. EPA, 1992a |
1 U.S. EPA, 1992a
U.S. EPA, 1992a
See # in Exhibit 4-3 ||
USDA, 1987 I
U.S. EPA, 1992a
approximate density of -
water under
environmental conditions
	 	
U.S. EPA, 1992a
U.S. EPA, 1992a
U.S. EPA, 1992a ~]|
U.S. EPA, 1992a 1
U.S. EPA, 1992a
U.S. EPA, 1992a
	 	 	 1
U.S. EPA, 1992a
U.S. EPA, 1992a T

" 	 : 	 1
constant
                        4-67

-------
4-68

-------
4-69

-------
    •• C
     o
    S
    c-
 t- —

 5 I

 H S

II
    65
    C
                                              4-70

-------
     I

     C
     u
     00 •
                 o
                 T3
                 n
                 «
                 _0

                 5


                 I
 £
 2
                 ts
                 s
      o

      §N
  £
  -a
  c
  ts
  c
  o

  I

  1
  CO

  S
  ON
              W



              I
     o
     ON
     ON
1
O
s.
.$>
  g
 o 3
tu a.
S  s
  5
  b

si
                              s
                              
                           oo
                           ON
                     •-- «n  .
                     2 2! R
                     & 52  s

                     *i^5ff§
                     llill;-!^
                «•!
                g s
      If
u

•S S
m CQ
                          « S
           Jf  3

           S 5 5
                           4-71

-------
  Example Exposure Calculations for Pathway 12

         The following example calculates  exposure of humans to  dioxins and dibenzofurans
  through ingestion of water and fish from surface water receiving eroded sewage sludge-amended
  soil from agricultural land.
  Step 1: Partitioning of Pollutant

        In Step 1 of the mass balance calculation, relationships among pollutant concentrations
  in the bulk sewage sludge-amended soil (Q, in the air-filled pore space (Q, and in the water-
  filled pore space (CJ are derived.  In this example calculation, these relationships are used to
  estimate Kwl and KlK in Step 2.               •


  Step 2: Estimation of Km

        Equation 4-28 can be used to calculate the loss rate coefficient for erosion (Kero):

                          j,         6xlO"4 mlyr       ,.,«-•?    i
                         Kero  = 	—LZ.	 = 4x10 3 yr'1
                                15 cm • 10~2  m/cm

 where:
       6x1 Q-4  =     de (average rate of soil loss due to erosion from sewage sludee-amended
                     land each year) from Exhibit 4-16,
       15      =     d (depth of incorporation for sewage sludge on agricultural land)  from
                  -   Exhibit 4-3, and
       10':    =     constant to convert (cm) to (m).
Step 2: Estimation of Knl


       Several equations are used to calculate the loss rate coefficient for volatilization (Kml).
First, the intermediate diffusivity variable £>„ is calculated from Eq. 4-30:


             Dei  = 4.4x10~2 cm2/sec •  10'4 m/cm2 • (0.4)1/3 = 3.2x10~6 m2/sec



where: .                                                                •
       4.4xlO'2       =     bm (diffusivity of pollutant in air)  from Exhibit 4-17,
       10"4           =     factor to convert (cm2) to (m2), and
       °-4           =     Oe (effective porosity of soil) from  Exhibit 4-16.
                                         4-72

-------
  4-32:
         Second, the particle density of the sewage sludge-soil mixture GO is calculated using Eq
  where:
         1400  =
         0.4    =
    * (bulk density of sewage sludge-amended soil) from Exhibit 4-3 and
6, (total porosity of soil) from Exhibit 4-16.
        Third, the dimensionless Henry's Law constant (H) is calculated using Eq. 4-33:
                     H =
                6.SxlQ-5atm-m3Imol
                           (0.082 L-atm/mol-K) - 288* • 0.001 m?IL
                        = 2.9xlO~3
 where:
        6.8xlO'5
        0.082
        288
        0.001
      H (Henry's Law constant) from Exhibit 4-17,
      R (universal gas constant) from Exhibit 4-16,'
      T (average air temperature in Kelvin) from Exhibit 4-16  and
      factor to convert (L) to (m3).
       Fourth, the intermediate diffusivity variable a, is calculated from Eq. 4-31:


                    a.  =	3.2x70•* m2/sec  • 0.4
   0.4
          2-3xl°3
                                                (1-Q.4) • 13.000 Lfke
                      = 2.0x10 -13m2/sec
                                                  1000 L/m
where:
       3,2x10-*
       0.4
       2.3X103
       13,000

       2.9xlO'3
       1000
     Dj (calculated above),
     6e (effective porosity of soil) from Exhibit 4-16
     pss (calculated above),
     Kd (partition coefficient for dioxins between water and soil) from
     Exhibit 4-17,                        ~          "
     A (calculated above), and
     constant to convert (m3) to (L).
                                         4-73

-------
        Next, to calculate Ca, Eq. 4-23 is used with a unit concentration of lkg/m3 for CT:
                                               kg/m:
[13,000 L/kg •  1400 kg/m3  • 0.001 m3/L\ +    0.2
                2.9x70 -3                    2.9x70 '3
                                                                           Q
 where:
        1

        13000
        1400

        0.001
        2.9xlO'3
        0.2
        0.2
         C, (unit concentration of pollutant in bulk sewage sludge-amended
         soil),
         Kd (soil-water partition coefficient) from Exhibit 4-17,
         BD^ (bulk density of sewage sludge-amended soil) from Exhibit
         4-3,
         constant to convert (L) to (m3),
         H (diniensionless Henry's Law constant) calculated above,
         0W (water-filled porosity) from Exhibit 4-16, and
         0a (air-filled porosity) from Exhibit 4-16.
4-29:
       Total average emissions from the soil surface hi one year are then calculated using Eq.
            Na   = 2 • 31,536,000 sec • 0.4  • 3.2x70 "6 /K2/sec  • 1.6x2Q-7 kgfm3
                   2.9x10
                             V/7t • 2.0x70 ~13 m2/sec • 31,536,000 sec
where:
       31,536,000   =
       0.4
       3.2x10-*
       1.6xlO'7

       2.0xlO:'3
        te (duration of emissions), corresponding to one year,
        0e (effective porosity of soil) from Exhibit 4-16,
        Da (intermediate diffusivity variable) calculated above,
        Ca (concentration of dioxins  in air-filled pore space) calculated
        above, and
        a, (intermediate diffusivity variable) calculated above.
                                          4-74

-------
         Finally, K^ can be calculated using Eq. 4-34:
                                         2.9x10-*
                                        0.15 kg/m2.
                                                    =  1.9x70
  where:
   2.9xlO'3

   0. 15
                            Nay (total average emissions from the soil surface in the first year),
                            calculated above, and
                            d (depth of incorporation of sewage sludge) from Exhibit 4-3; see
                            text for explanation of why this may be expressed as a mass per
                            area.
 Step 2: Estimation of

        Equation 4-44 can be used to approximate the loss rate coefficient for leaching
KUc «
                                            0.5  m/yr
                                                           _
       [1400 kg/m3  • 13,000 L/kg • 0.001 m3/L + 0.2 + 2.9xlO~3  • 0.2]  • 0.15

    =  1.8x70-* yr~\
                                                                                 m
 where:
  °-5
  1400

  13,000
  0-°°1
  °-2
  °-2
  2.9xlO'3
  °- 15
Step 2: Estimation of K
                       M
                           NR (annual recharge to ground water) from Exhibit 4-16,
                           BD^ (bulk density of sewage sludge-amended soil) from Exhibit
                           4-3,                      -
                           Kd (soil-water partition coefficient) from Exhibit 4-17,
                           constant to convert (L) to (m3),
                           0* (water-filled porosity) from Exhibit 4-16,
                           ^? (air-filled porosity) from Exhibit 4-16,
                           H (dimensionless Henry's law constant) calculated above, and
                           d (dePth of hicorporation of sewage sludge) from Exhibit 4-3.
       The total loss rate for dioxins  from the sewage  sludge-amended agricultural land is
calculated from Eq. 4-26:
                                         4-75

-------
          Ktot = 4*10
                                                 ~l  + 1.8x10 ~* yr~l
              = 2.3x70 ~2 yr
                              ~2   '1
  where:
  4x10°
  1.9xlO-2
  1.8x10"*
  0
                             Kero (loss coefficient for erosion) calculated above,
                             Kwl (loss coefficient for volatilization) calculated above,
                             KlK (loss coefficient for leaching) calculated above, and
                             Kdeg (loss coefficient for degradation) from Exhibit 4-17.
        Maximum Pollutant Mass Available for Erosion

        Once Ktot is calculated, it is then used in Eq. 4-45 to calculate the maximum mass of
 pollutant onsite:
    2J*S_  .
           35 mg/ha
                        kg
                                                                              kg_  .
                                                                              Mg
 where:
 S.llxlO"4
 1
 2.3xlO'2
 19
                            AR (application rate) from Exhibit 4-3,
                            Cj (concentration of dioxins in sewage sludge) from Exhibit 4-1,
                            c (application interval) .from Exhibit 4-3,
                            Km (total loss rate for dioxins) calculated above,
                            b (equal to integer part of (AT-l)/c, where TV is the site life),  from
                            Exhibit 4-3,
                            constant to convert (Mg) to (kg), and
                            interval of time over which pollution loss is evaluated.
       To calculate the mass of pollutant left in the sewage sludge-amended soil at the end of
an individual's lifetime, Eq. 4-46 is used:
where:
35
                              = 35 mg/ha

                              = 11 mg/ha
                           TPN (total mass of dioxins available at a site after the final year of
                           application) calculated above,
                                          4-76

-------
         2.3xlO'2      =     Km (total loss rate for dioxins) calculated above,
         70            ='    LS (average human lifetime), assumed to be 70 yr  and
         20            =     ATV (site life) from Exhibit 4-3.
         Then, f^ can be calculated using Eq. 4-47:




              -         20 yr  •
                                                             Mg)      ha
                            20 yr • 3.11x10-*' 28-' •  7 Mg •  1000 -**'
                                              kg    ha-yr        Mg
                    = 0.75



  where:
        20           =     ^(number of years sewage sludge is applied to land) from Exhibit
                            4-3,

        S.llxlQ-4     =     q , (concentration of dioxins in sewage sludge) from Exhibit 4-1
        7             -     AR (application rate) from Exhibit 4-3,

        1000          =     constant to convert (Mg) to (kg), and '                    •' •   -
        11            =     Mu  (mass of dioxms  in soU at end  of period  equal  to an
                            individual's lifetime) calculated above.



 Pollutant Concentration on Eroded Soil
 site (C^) 'reoukes ^^"T"**1 °f P°Uutant on soil erodinS from the land application
 Sfh»  ? /    q    * ?  additional parameters to be calculated.  First, the fraction of total
 pollutant loss caused by erosion is calculated by Eq. 4-27:                   "*-u«n or total
where:
                               f   _         yr      n^
                              fero  = - T^ - = 0.17
                                     2.3x10-*  r~l
                           5* (1°SS coefficient for erosion) calculated above, and
                              (total loss rate for dioxins) calculated above.
4-49
(-   Second, the calculated rate of soil loss for a land application site is calculated using Eq.
                                         4-77

-------
                           = 6x10 ^ m/yr • 1400 kg/m3 -  10,000 m2/ha

                           - 8400 kg/ha-yr
  where:
        6x10^

        1400

        10,000
  de (average rate of soil loss due to erosion from sewage sludge-
  amended land each year) from Exhibit 4-16,
  BDmu (bulk density of sewage sludge-amended soil) from Exhibit
  4-3, and
  constant to convert (ha) to (m2).
        Then, Csitetj can be calculated using, Eq. 4-48:
                      20 yr  • S.llxlO-4 ^ - 7 -^- - 1000  -ZL - 0.17  • 0.75
          r        =	*g     ha-yr	Mg
            siu,dioxaa                            ~~r	——	
                                        8400 —%— - 70 yr
                                               ha-yr
                    = 9.5x10-* 2£
                               kg
 where:
       20

       3.11x10^
       7
       1000
       0.17

       0.75

       8400
       70
 N (number of years sewage sludge is applied to land) from Exhibit
 4-3,                  .
 Cj (concentration of dioxins in sewage sludge) from Exhibit 4-1,
 AR (application rate) from Exhibit 4-3,
 constant to convert (Mg) to (kg),
fm (fraction of total pollutant loss caused by erosion) calculated
 above,
fus (fraction of total cumulative loading lost hi individual's lifetime
 to all four loss processes) calculated above,
MEsi!e (rate of soil loss) calculated above, and
LS (lifetime of an individual), assumed to be 70 years.
       A dilution factor, to represent the extent to which eroded soil from the land application
site is  diluted" by soil from the untreated remainder of the watershed, is calculated using Eq
4-51.  First, the -sediment delivery ratios for the land application site and watershed are
calculated using Eqs. 4-52 and 4-53:                                            .
                                         4-78

-------
                               = 0.872  • (1074 to)"0-125 = 0.36
                               = 0.872  • (440,300 fez)"0'125 = 0.17
  where:
        1074

        440,300
                            Asite (area of land application site treated with sewage sludge) from
                            Exhibit 4-16, and
                                (area of the watershed) from Exhibit 4-16.
 Then the dilution factor is calculated using Eq. 4-51:   .

                 D  = _         1074 ha -0.36   _
                   f   (1074 ha • 0.36)  + [(440,300 ha  -  1074 ha) • 0.17]

                     = 5.2xlO-3     .      .
 where:
       °-36

       °-17
                     $te (sediment delivery ratio for land treated with sludge) calculated above
                     and                                                               '
                     Swt (sediment delivery ratio for the watershed) calculated above.
Eq  4-5?e
                      C°nCentration of P°llutant m erod«i soil (Cao^ can be calculated using
                                     = 5.2x10-* • 9.5X10-62$.
where:
      5.2x10^
      9.5x10
                    *
                                                kg
                           ^(dilution factor) calculated above, and
                           c^j  (concentration of dioxins  in sewage sludge-amended soil
                           eroded from the land application site) calculated above.

                                 t0 CalCUlate ** concentratio° of Pollutant dissolved in the
                                         4-79

-------
4.9x70 ~8
                                         16
                                                           10   kgfmg
                               6.5XJ0'13 mgIL
 where:
4.9xlO'8

16

13,000
                                 j  (dry  weight  concentration of  dioxins  in eroded  soil)
                            calculated above,
                      =     TSS (concentration of total suspended solids in the surface water)
                            from Exhibit 4-16,
                      =     Kd (soil-water partition coefficient for dioxins in the stream) from
                        , '   Exhibit 4-17, and
                      =     constant to convert (mg) to (kg).
 Exposure Calculations

        Potential human  exposure to dioxins through  direct ingestion  of surface  water is
 calculated using Eq. 4-59:
                                     _ 6.5x20 713 mg/L • 2 L/day
                                     =                -
                                     = l.SxlO -14 mg/kg-day
 where:
       6.5xlO'13
       2
       70
                    Cswj (concentration of dioxins in surface water) calculated above,
                   IW (ingestion rate of water) from Exhibit 4-16, and
                   BW (body weight), assumed to be 70 kg.
       Potential human exposure to dioxins through  consumption of  contaminated fish  is
calculated using Eqs. 4-60 through 4-63.  First, the BCF for dioxins is calculated using Eq. 4-
60:
                         log.JBCF) = 0.79 - 6.64  - 0.80 = 4.4
where:
       6.64   =     log10(/$roHI) from Exhibit 4-17.
                                          4-80

-------
  The BAF is calculated using Eq. 4-61:


                               BAF = 28,000 • 10  = 2.8xl05

  where:
         28,000       =     BCF (bioconcentration factor for dioxins) calculated above by
                            exponentiating log10(5CF), and
         10           =     FM (food chain multiplier for dioxins) from Exhibit 4-17.

                               /                                           .
  The concentration of dioxins in fish fillets is then calculated from Eq.. 4-62:


                         CffJ = 6.5x10 ,'13 mg/L • 2.Sxl05 L/kg • 0.5

                             = 9.0x70 ~8 mg/kg


 where:
        6.5xlO"13     =     C^j (concentration of dioxins in surface water) calculated above,
        2.8X105      =     BAF (bioaccumulation factor for dioxins) calculated above, and -'
        °-5          =     pf (ratio of pollutant concentration in fillet to whole  fish) from
                            Data Inputs.


 Human exposure through ingestion of fish fillets is then calculated using Eq. 4-63:


                       EXp      = 9.0x20 -* mg/kg •• 0.04  kg/day
                         .   /•*—'" :            70kg

                                  = 5.2x20 -11 mg/kg-day


where:                                                           .
      - 9.0xlO'8      =     CffJ (concentration of dioxins in fish fillets) calculated above,
       °-04          =     IF (daily ingestion of fish) from Exhibit 4-16,  and
       70            =     BW (body weight), assumed to be 70 kg.


       Total exposure to dioxins in surface water is the sum of the exposures to dioxins in water
and fish, as shown in Eq.  4-64:
                                         4-81

-------
                            = '1.8x70-14 mg/kg-day + 52x20-nmg/kg-day

                            = 5.2x10'" mg/kg-day
  where:
        l.Sxlfr14      =     EXPw,j (exposure to dioxins through ingestion of surface water),
                            calculated above, and                                        '
        5.2x10-"      =     EXPf.j (exposure to dioxins through ingestion of fish) calculated
                            above.
 4.2.13        Pathway 13 - Inhalation of Pollutants Volatilized from Land-Applied Sewage
               Sludge

        Pathway 13 evaluates human exposure to pollutants volatilizing  from both agricultural
 and non-agricultural lands to which sewage sludge has been applied.   Non-agricultural lands
 include forests, reclamation sites, and public contact sites.
                                                                             ir
        To estimate exposure for this pathway, a mass balance analysis is required  This mass
 balance analysis accounts for the partitioning of pollutants into different soil phases (solids  air-
 and water) and the subsequent losses of pollutants from the land application site. Pollutants are
 lost from a  land application site by:  erosion of contaminated soil particles, which releases
 pollutants into surface waters; volatilization of pollutants into  air;  leaching of pollutants  into
 groundwater; and degradation. A mass balance for a pollutant must be maintained, given these
 four competing loss processes of erosion, volatilization, leaching, and degradation  Once mass
 balances for  pollutants  have  been established,  exposures to  pollutants that have eroded
 volatilized, or leached are calculated under three separate pathways: surface water (Pathway 12)'
 air (Pathway 13), and groundwater (Pathway 14).  Pollutants which have degraded are assumed
 to have degraded into chemicals that do not pose unacceptable risks to public health  or  the
 environment.

       The methods for performing the mass balance calculation for Pathways 12  13 and 14
 are discussed in Section  4.2.12.  In this section,  the equations particular to Pathway 13   for
 estimating the pollutant mass expected  to volatilize and its transport to the downwind edge of
 the land application site, are presented. Note that volatilization is assumed to occur within a
 one-year period; any contribution to volatilization  from sewage sludge applied in prior years is
considered negligible.                                                            J
                                         4-82

-------
  Methods Specific to Pathway 13

         There are two major steps required to estimate the concentration of a volatilized pollutant
  in air at the downwind edge of the land application site:

         1)     Using the mass balance calculations presented hi Section 4.2.12, the mass
               of pollutant expected to volatilize from the land application site within a
               period  equivalent to a human lifespan is estimated.

        2)     Using a simplified version of the Industrial Source Complex Long Term
               Model  (ISCLT), the transport and dispersion of pollutant in ambient an-
               al the downwind edge of the land application site are modeled.

        In the first step, the rate at which a pollutant volatilizes from the site is estimated, based
 on the assumption that equilibrium has been achieved between annual pollutant loadings and total
 losses:                                                      -
                                 ^j--AR-Cj-f^     .                 (4-65)


 where:
        FA^j  =     annual average flux of pollutant j volatilizing from the-sewage sludge-
                     amended soil (kg pollutant/ha-yr),
        0.001  =     constant to convert units from (Mg-mg/kg) to (kg),
        AR     =     annual whole sludge application rate of sewage sludge to land (dry Mg
                     sewage sludge/ha-yr),
        Cj      =     concentration of pollutant j  in sewage sludge (mg pollutant/kg sewage
                     sludge), and
     .  /«,„      -  .   fraction of total pollutant loss caused by volatilization (dimensionless).


 The fraction of total pollutant loss caused by volatilization is obtained from the mass balance
 calculation presented hi Section 4.2.12.

       In the second step, pollutant concentrations  in ambient air at the downwind edge of the
 land application site are estimated, based on pollutant fluxes from the site.  The model used to
 simulate^transport of pollutants from treated land is described by U.S. EPA (1986d) and is based
 on equations provided by Environmental.Science and Engineering (1985).  These equations are
 simplifications  of equations used hi ISCLT.

  •     The exposed individual is assumed to live within 1 km of the land application site and
to be exposed to concentrations present at the downwind edge of the land application site  A
source-receptor .ratio is calculated to relate the concentration of pollutant in ambient air at'that
mdividual s  location (g/m3) to.the rate at which that pollutant is emitted from the treated soil
(e/m-sec):
(g/m2-sec):
                                         4-83

-------
                                     - 2fW9  A*  ' V '  10>QO°
                                     - 2.032 — - - . —                      (4-66)
                                              (r  + *P ' u  • az


  where:
         SRR          =     source-receptor ratio (sec/m),
         2.032         =     empirical constant,      '    .
         Asue           —  '   area of land application site (ha),
         v             =     vertical term for dispersion of pollutant in air (dimensioriless),
         10,000        =     constant to convert (ha) to (m2),
         r>             =     distance from center of the land application site to the downwind
                              edge(m),
        xy             ~     ^teral virtual distance  to land application site (m),
        u      .       =     average wind speed (m/sec), and
        °i             =     standard  deviation  of  the  vertical  distribution  of pollutant
                             concentration hi air (m).
 rr ^        vertical term (v)  is a function of source height, the mixing layer height and a
 Under stable conditions the mixing layer height is assumed infinite, and for a pollutant releas'e"
 height of zero, v=l.  The lateral virtual distance is the distance from a virtual point source to
 the land application site, such that the angle 6 subtended by the site's width is 22 5°   This
 distance is calculated as:                                                        '   '
                                   _   A^-10,000      e
                                x  -  \	cot —                        (4-67)
                                      N     •' it            2
        The distance from  the  center of the land application site to the downwind  edge is
 calculated assuming a square land application site:
                                               • 10.000
at™ J?' T^   f     ,°f **•VertiCal distribution of concentration (az) is defined by an
atmosphenc stability class and the distance from the center of the site to the downwind edge
Exhibit 4-18 provides values for two parameters, a and b, for a range of distances under stable
                                          4-84

-------
  atmospheric conditions.  Based on values from this table, an appropriate value of a is calculated
 .as:                                                                         z
                                         az  = a or*
                                           (4-69)
  where r
x =.
                                                                                  (4-70)
 and:
        x      -     distance from the center of the land application site to the downwind edge
                     (km), and
        10'3    =     constant to convert (m) to (km).
                                     EXHIBIT 4-18
               Parameters Used to Calculate 
-------
        Once the source-receptor ratio has been estimated, it is combined with the estimated
  average flux of pollutant to predict the average concentration of pollutant in ambient air at the
  downwind edge of the site:
                                airj
                                             SRR • 0.00317
                                                                          (4-71)
 where:
        0.00317
                     average concentration of pollutant y in ambient air at the downwind
                     edge of the site (pg pollutant/m3 air), and
                     constant to convert (kg/ha-yr) to (/*g/m2-sec).
 Estimating Human Exposure

        The estimated concentrations of pollutants in air are converted to estimates of human
 exposure based on assumptions about the rate at which the average individual inhales air:
                                EXP. =
                                    3
                                         10"3 • C
                                              BW
                                                                         (4-72)
 where:
EXPj  -
lO"3   -

IA'*   -
BW   -
                    exposure to pollutant./ in sewage sludge (mg pollutant/kg body weight-
                    day),
                    constant to convert (/*g) to (mg),
                    average concentration of pollutant j in ambient air (jig pollutant/m3 air),
                    inhalation rate (m3 air/day), and
                    body weight (kg).
Data Inputs

       All the non-pollutant-specific data inputs required for this pathway are presented in
Exhibit 4-16 and all the pollutant-specific parameters are presented in Exhibit 4-17,  both hi
Section 4.2.12.  As shown in Exhibit 4-16, the daily inhalation rate for humans is assumed to
be 20 m /day, the average wind velocity is assumed to be 4.5 m/sec,  and the average air
temperature is assumed to  be 288 K.
                                         4-86

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  Example Exposure Calculations for Pathway 13


        The following example  calculates exposure of humans to  dioxins and dibenzofurans
  through inhalation of dioxins volatilized from sewage sludge-amended soil on agricultural land.
  The mass balance portion of the calculation, which is the same for Pathways 12, 13, and 14, is
 presented in the section "Example Exposure Calculations for Pathway 12". In the mass balance
 calculation, /w/ is estimated from Eq. 4-27:                                  .
                                      2.3*10-2/yr
 where:
 1.9 x 10"2

 2.3 x 10'2
                           Kw[ (loss rate due to volatilization of dioxins from sewage sludge-
                           amended land) calculated in Pathway 12, and
                           Kut (total loss rate for dioxins from sewage sludge-amended land)
                           calculated hi Pathway 12.
       Equation 4-65 is used to estimate the annual average flux of dioxins volatilizing from
sewage sludge-amended land:                                                        .  -
                           = 0-001 • IMglha-yr -3.1 1x10 ^mg/kg • 0.82
where:
3.11x10^

0.82
                          constant to convert (Mg-mg/kg) to (kg),
                          AR (annual whole sludge application rate of sewage sludge to land)
                          from Exhibit 4-3,
                          Cj (concentration of dioxins in sewage sludge) from Exhibit 4-1
                          and
                          fwl  (fraction of total  pollutant  loss  caused by volatilization)
                          calculated above.
      The source-receptor ratio is then calculated by Eq. 4-66. Three variables, x  r' and a
         ^6e7stimated-  ^ lateral virtual distance to the land application site, Xy, £ calculated
                                        4-87

-------
                       '  x       1074/m  • lQ,OOOm2/ha  m ^22.5

                            = 9295 m


 where:                      •
        1074         =    Asite (area of land application site treated with sewage sludge) from
                           Exhibit 4-16,
        10,000       =    constant to convert (ha) to (m2), and
        22.5         =    6 (the angle subtended by the site's width) from Exhibit 4-16.
        The standard deviation of the vertical distribution of concentration (o^) is then calculated
 using Eqs. 4-68 through 4-70.  The distance from the center of the land application site to the
 downwind edge is calculated using Eq. 4-68:
                             , , V1074/M • 10,000 =
                            r  ,
where:
       1074   -     Asitf (area of land application site treated with sewage sludge) from Exhibit
                    4-16, and                               '          .      <
       10000  =     constant to convert (ha) to (m2).


The distance from the center of the land application site to the downwind edge is then converted
to kilometers using Eq. 4-70:
                           x = 10'3 km/m • 1639m  = 1.6 km
where:
       10'3   =     constant to convert (m) to (km), and
       1639  =     r' (distance from center of the land application site to the downwind edge)
                  .  calculated above.
                                        4-88

-------
  Then the standard deviation of the vertical distribution is calculated using Eq. 4-69:
                                   = 13.953 • 1.6a63227 =  19m
where:
       13.953
       0.63227
                             a (corresponding to x = 1.6 km) from Exhibit 4-18, and
                             b (corresponding to x = 1,6 km) from Exhibit 4-18.
        The source-receptor ratio can then be calculated using Eq. 4-66:
 where:
      2.032
      1074

      1
      10000
      1639

      9295
      4.5
      19
                  SRR = 2.032 •

                       = 23sec/m
                                           1074te- 1 • 10.000
                                   (1639m  + 9295m) "• 4.5m/sec  • 19m
                     empirical constant,
                     Asiu (area of land application site treated with sewage sludge) from Exhibit
                     4-16,                                     -                    .
                     v (vertical dispersion term) from Exhibit 4-16,
                     constant to convert (ha) to (m2),
                     r' (distance from center of the land application site to the downwind edee)
                     calculated above,                                                 6 '
                     Xy (lateral virtual distance to land application site) calculated above
                     u (wind speed) from Exhibit 4-16, and
                     a (standard deviation of the vertical distribution of concentration in air)
                     calculated above.
                                                                   of
                  c
                      air,
-------
         Potential  human exposure to dioxins through  inhalation  of dioxins volatilizing from
  sewage sludge-amended land is calculated from Eq. 4-72:
                                 - 10"3 •  1.3x70-7u.g/m3 • 20m3/day
                                 ~              WJT-.	

                                 = 3.8xlO-nmg/kg-day
 where:                                                •                       ,
        10"3           =     constant to convert (/zg) to (kg),
        l.SxlO"7       =     C&j (average concentration of dioxins hi ambient air) calculated
                            above,           *
        20            =     IA (daily inhalation volume) from Exhibit 4-16, and
        70            =     BW (body weight), assumed to be 70 kg.


 4.2.14       Pathway 14 - Ingestion of Groundwater Containing Leached Pollutants

       Pathway 14 evaluates human exposure to pollutants through ingestion of groundwater that
 receives leachate from agricultural and non-agricultural lands to which sewage sludge has been
 applied.  Non-agricultural lands include forests, reclamation sites, and public contact sites.

       To estimate exposure for this pathway, a mass balance analysis is required. This mass
 balance analysis accounts  for the partitioning of pollutants into different soil phases (solids  air
 and water) and the subsequent losses of pollutants from the land application site. Pollutants are
 lost from a land  application site by: erosion of contaminated soil particles, which  releases
 pollutants into surface waters;  volatilization of pollutants into ah-; leaching of pollutants into
 groundwater; and degradation.  A mass balance for a pollutant must be maintained, given these
 four competing loss processes of erosion, volatilization,  leaching, and degradation   Once mass
 balances for pollutants have been established,  exposures  to pollutants that  have  eroded
 volatilized, or leached are calculated under three separate pathways: surface water (Pathway 12)'
 air (Pathway 13), and groundwater (Pathway 14).  Pollutants which have degraded  are assumed
 to have degraded  into chemicals that do  n6t pose unacceptable risks .to public health or the
 environment.

       The methods for performing the mass balance calculation for Pathways 12  13  and 14
are discussed hi Section 4.2.12.  In this section, the equations particular to Pathway  14  for
estimating the  concentration of pollutant in leachate from a site and modeling the  transport of
that pollutant to the groundwater, are presented.
                                                                                             *
                                         4-90

-------
  Methods Specific to Pathway 14

         There  are  two  steps  required  to  estimate  the  concentration  of each  pollutant in
  groundwater near the land application site:

         1)     Determine the concentration of pollutant in water leaching through the
                treated soil.

         2)     Use mathematical  models for  the  transport of pollutant  through the
                unsaturated and saturated soil zones to estimate expected  concentrations
                of pollutant in groundwater.

         The maximum mass of pollutant available for leaching from a site is estimated first  For
• all organic pollutants, except dioxins and dibenzofurans and coplanar PCBs, it is assumed that
  pollutant concentrations gradually increase in the soil until the rates of annual loss equal the rates
  of annual loading, and steady-state is achieved. At steady-state, the rate at which the organic
  pollutant leaches from the site  can be determined from the annual loading  (which equals total
  annual losses) and the fraction  of total losses attributable to leaching:


                               FA*cj  =  AR • Cj 'fuc ' °-001                        (4-73)


 where:                   ,
       FAleCf j  =     annual average flux of pollutant j leaching from sewage sludge-amended
                     soil (kg pollutant/ha-yr),
       AR     =     annual whole sludge application rate  of sewage sludge to land (dry  Me
                     sewage  sludge/ha-yr),
       Cj     =     concentration of pollutant j in sewage sludge (mg  pollutant/kg sewaee
      ,      '         sludge),      .                                              *      5
       •fbm   =     fraction of total pollutant loss caused by leaching (dimensionless), and
       0.001  -     constant for converting units from (Mg-mg/kg) to (kg).


       For inorganic pollutants, dioxins and dibenzofurans, and coplanar PCBs  sewage sludge
is assumed to be applied over a 20 year period, followed by an inactive  period.  During the
inactive period, pollutant is depleted from the treated soil by leaching and erosion, and for the
two classes of organic pollutants, volatilization and degradation, as  well. To simulate potential
contamination of groundwater, the loading of pollutant into the unsaturated zone is "linearized"
into a pulse of constant magnitude to represent the maximum annual loss of pollutant (in ke/ha-
yr) occurring  over the 300-year simulation  period modeled.  The duration of that pulse  is
calculated so that pollutant mass is conserved. For land application sites, the maximum rate of
loss is expected in the year immediately following the last application of sewage sludge  because
the concentration of pollutant at the site reaches its peak at that time. As explained in Appendix
C, this peak loss rate could be maintained for a maximum length of time described by
                                         4-91

-------
                                               N  '
                                    TP =	:—=—                            (4-74)
                                                                                      '
 where:
        TP    =     duration of "square wave" for approximating the loading of pollutant into
                     the unsaturated soil zone (yr), and
        N     =     total number of years sewage sludge is applied to land (yr).
        This result is combined with an estimate of the fraction of total pollutant loss to leaching
 for a conservative estimate of the average flux of pollutant leaching from the land application
 site:                                                      *
                                                                                 (4-75)
                                                '7*2)
 The fraction  of total  pollutant loss caused by leaching is -obtained  from the mass  balance
 calculation presented hi Section 4.2. 12.

       For both organic and inorganic pollutants, the estimated flux from either Eq. 4-73 or Eq.
 4-75 can 'be  combined with  the assumed rate of net  recharge -to groundwater at the  land
 application site to derive an estimate of the average concentration of pollutant in the leachate:
                                                                                (4-76)
                                              NR
where:
       Q«,y   =     average concentration of pollutant j in water leaching  from the sewage
                    sludge-amended soil (mg pollutant/L water),
       0.1    =     constant to convert, units from (kg/ha-m) to (mg/L), and
       NR    =     annual recharge to groundwater beneath the treated soil  (m recharge/yr).


       Next, the  leachate concentration is used to estimate the concentration  of pollutant in
drinking water wells near the site.   Two mathematical models are  combined  to calculate an
expected ratio between these two concentrations.  The Vadose Zone Flow and Transport finite
element module (VADOFT) from the RUSTIC model (U.S.  EPA, 1989d,g) is used to estimate
flow and transport through the unsaturated zone, and the AT123D analytical model (Yeh,  1981)
is used to estimate pollutant transport through the saturated zone.
                                         4-92

-------
         VADOFT allows consideration of multiple soil layers, each with homogeneous soil
   characteristics. Within the unsaturated zone, the attenuation of organic pollutants is predicted
   based on longitudinal dispersion, an estimated retardation coefficient derived from an equilibrium
   partition coefficient, and a first-order rate of pollutant degradation. The input requirements for
   the unsaturated zone module include various site-specific and geologic parameters and the rate
   of gfoundwater recharge in the area of the site. It is assumed that the flux of pollutant mass into
   the unsaturated zone beneath a land application site can be represented by results from the mass
   balance calculations described above.  Results from analysis of the unsaturated zone give the
   flow velocity and concentration profiles for each pollutant  of interest.  These velocities and
   concentrations are evaluated at the water table,  converted to a mass flux, and used as input to
   the AT123D saturated zone module.

         The flow system hi the vertical  column is solved with VADOFT, that  is  based  on an
   overlapping representation of the unsaturated and saturated zones.  The water flux into the
  unsaturated zone is specified for the bottom of the zone of incorporation for sewage sludge In
  addition, a constant pressure-head boundary  condition is  specified for the  bottom of the
  unsaturated zone beneath the land application site.  This pressure-head is chosen to be consistent
  with the expected  pressure  head  at  the  bottom of  the saturated  zone.   Transport in the
  unsaturated zone is determined using the Darcy velocity and saturation profiles from the flow
  simulation:  From these, the transport velocity profile  can be determined.
»                  -                                    •

        Although limited to one-dimensional flow and transport, the use of a rigorous finite--
  element model  in the unsaturated zone allows  consideration of depth-variant physical  and
  chemical processes that would influence  the mass flux entering the saturated zone  Among the
  more important of  these processes are  advection (that  is a function of the Darcy  velocity
  saturation and porosity), mass dispersion, adsorption of the leachate onto the solid phase and
  both chemical and biological degradation.                                    .       •'

        To represent the variably saturated  soil column beneath the application site the model
  discretizes the  column into a finite-element grid consisting of a series of  one-dimensional
  elements connected at nodal points.   Elements can be  assigned different  properties for the
  simulation of flow in a heterogenous system. The model generates the grid from user-defined
 zones; the user defines the homogeneous properties of each zone,  the zone thickness and the
 number of elements per zone, and the code automatically divides each zone into a series of '
 elements of  equal length.  The governing  equation is  approximated using the Galerkin finite
 element method and then solved iteratively for the dependent variable (pressure-head) subject
 to the chosen initial and boundary conditions. Solution of the series of nonlinear simultaneous
 equations  generated by the Galerkin scheme is  accomplished by either Picard  iteration a
 Newton-Raphson algorithm or a modified Newton-Raphson algorithm.  Once the finite^element
 calculation converges, the model yields  estimated values for all the variables at each of the
 discrete  nodal points.   A detailed description of the solution scheme is found  in U.S.  EPA
 \ •   o/*

       One-dimensional, advective-dispersive transport is estimated with VADOFT based on the
estimated mass  flux of pollutant into the top of the soil column, and  a zero  concentration
vT^Sr    f °n at **  b0tt°m °f ** saturated zone-  ^ resuWng mass flux from the
VADOFT simulation is used as input for the AT123D model, that simulates pollutant transport

                                         4-93

-------
  through the saturated zone. It is represented as a- mass flux boundary condition applied over a
  rectangular area representative of the land application site. The transient nature of the flux into
  the saturated zone is represented by tune-dependent levels interpolated from the results generated
  by the VADOFT  simulation.

        As in calculations for the unsaturated'zone, degradation of organic pollutants is assumed
  to be first-order during transport through the aquifer. Speciation and complexation reactions are
  ignored  for metals, leading to the possible over- or underestimation of expected concentrations
  of  metals  in groundwater at  the location of a receptor well.  Detailed descriptions  of  the
  AT123D model are provided by U.S. EPA (1986d) and by Yeh (1981) and will  not be repeated
  here.  In general, the model provides an analytical solution to the basic advective-dispersive
  transport equation.  One advantage of AT123D is its flexibility: the model allows the user up
  to 450 options and is capable  of simulating a wide variety of configurations of source release
  and boundary conditions.  For  the current application, AT123D uses the  source  term from
  VADOFT and other input parameters to predict concentrations of pollutant within 300 years in
  a receptor well at  the downgradient edge of the land application site.

  Estimating Human Exposure

        Once pollutant concentrations in groundwater are estimated, estimates of human exposure
 are  made based on assumptions  about the rate that the average individual consumes drinking
 water. Potential exposure through ingestion of contaminated groundwater is estimated as:


                                            C    • TW
                                   EXP. =   welj                                 (4-77)
                                       '      BW
 where:
       EXPj  =     exposure, to pollutant j in sewage sludge (mg pollutant/ke body weight-
                     day),
       CUt/  =     concentration of pollutant j in well water (mg pollutant/L water),
       TW    =     volume of water ingested daily (L water/day), and
       BW   =     body weight (kg).


 Data Inputs

       All the data inputs required for this pathway are presented in Section 4.2.12.

 Example Exposure Calculations for Pathway 14

       The following example calculates exposure of humans  to dioxins and dibenzofurans
 through ingestion of groundwater that has received leachate from sewage sludge-amended soil
on agricultural land.   The mass balance portion of the calculation,  which is the same for
Pathways 12,  13, and 14, is presented  in the section "Example Exposure Calculations for
Pathway  12".  In the mass balance calculation, f^ is estimated from Eq. 4-27:

                                         4-94

-------
                                                _ 7R    3
                                                ~ 7.0x10
                                     2.3xlQ-2/yr


  where:

        1.8 x 10^  .   =     Kkc (loss rate due to leaching of dioxins from sewage sludge-
                            amended land) calculated in Pathway 12, and
        2.3 x 10'      =     Kut (total loss rate for dioxins from sewage sludge-amended land)
                            calculated in Pathway 12.



        The duration of the  square wave for approximating the loading of dioxins into the
 unsaturated soil zone is calculated using Eq. 4-74:
                                £1 _ g



 where:

       20         •   = •'   N 
-------
        Eq. 4-76 is then used to calculate the average concentration of pollutant in the. leachate:
                                     =  0.1  • 6AxlQ-9kglha-yr
                                               0.5m/yr
                                     = 1.3xlQ-9mg/L
 where:
 0.1
 6.4xlO-9

 0.5
                            constant to convert units from (kg/ha-m) to (mg/L),
                            FA^ j (annual flux of dioxins leaching from the site) calculated
                            above, and
                            NR (net recharge to groundwater in treated area) from Exhibit 4-
                            16.
       The concentration of dioxins hi leachate is then converted into a  well concentration
 through the use of VADOFT and AT123D. The concentration of dioxins hi the well is estimated
 to be 0 mg/L; i.e., dioxins are not transported through the unsaturated and saturated zones to
 the  well  hi  appreciable concentrations.   Using  Eq. 4-77, human  exposure to  dioxins hi
 groundwater is thus estimated to be:
where:
0

2
70
                     Cweij (concentration of dioxins in well water) obtained through VADOFT
                     and AT123D modeling,
                     IW (quantity of water ingested daily) from Exhibit 4-16, and
                     BW (body weight), assumed to be 70 kg.
4.2.15        Pathway 15 - Infant Exposure to Pollutants Through Breastfeeding

       Pathway 15 evaluates exposures of infants to pollutants hi breast milk.  Only highly
lipophilic pollutants are  evaluated because  these  are  expected  to . concentrate  in milkfat.
Concentrations of pollutants hi breast milk result in part from the mother's exposure to pollutants
in sewage sludge through several human exposure pathways, including pathways 1,  2, 4, 5, 12,
13 and 14, as described in previous sections.  In addition, the mother is assumed to be exposed
to background concentrations of pollutants from sources other than sewage sludge. This analysis
presents two exposure  scenarios  that differ hi exposure duration and/or percent of an infant's
lifetime over which dose is averaged.
                                         4-96

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  Methods

        The method used to estimate infant exposure is taken from Estimating Exposures to
  Dioxin-Like Compounds (U.S. EPA, 1994b), and is based on an approach developed by Smith
  (1987).  The method assumes that the concentration of pollutant in breast milk fat is the same
  as the concentration in maternal fat.  The following calculation is used:
                                                + mS!Udge.J>' hj '/I. /
                                               0.693
                                                                                    (4-78)
 where:
            ».y


        ^background, j


        "^sludge, j
                      -     concentration of pollutant/ in maternal milk (mg pollutant/kg milk
                            fat),                             •
                            maternal intake of pollutant / from sources other than sewage
                            sludge (mg pollutant/kg body weight-day),
                      =     maternal intake  of pollutant / from  relevant  sewage  sludge
                            exposure pathways (mg pollutant/kg body weight-day),
                      =     half-life of pollutant j in adults (days),
                      =     proportion   of  ingested  pollutant /   that  is   stored  in  fat
                            (dimensionless),                                        '  '.'" ~
                      =     ln(0.5),  to  convert the half-life of  pollutant  / into a  rate
                            (dimensionless), and
       •^    •   •   ' '   =     proportion of mother's weight that is fat (kg maternal fat/kg total
                            body weight).

This steady-state model assumes that the pollutant levels in maternal fat remain constant i e
changes m maternal levels of pollutant during breastfeeding do not occur.

       The concentration of pollutant in mother's milk is then used in the following equation to
estimate the daily dose to the infant:                            .
       0.693
                                                    AT
                                                                                  (4-79)
where:
      IM
      ED
                           infant's average daily exposure to pollutant/ (mg pollutant/kg body
                           weight-day),
                           proportion of fat hi breast milk (dimensionless),
                           proportion of ingested pollutant/ that is absorbed (dimensionless),
                           ingestion rate of breast milk (kg milk/day),
                           exposure duration (yr),
                                          4-97

-------
                      =     average body weight of the infant during the exposure period (kg),
                            and
        AT           =     averaging time (yr).


        Daily doses to the infant are determined for each of the two following scenarios, which
  are distinguished by  exposure duration and averaging time:

        Scenario 1:   An infant breastfeeds for one year and the daily dose is averaged over this
                     •one year exposure period.   Infant body  weight at one-half  exposure
                     duration (six months) is used to represent the average weight-over the
                     exposure duration in this scenario.

        Scenario 2:   Under the second scenario, the infant breastfeeds for two years. The dose
                     is averaged over 70 years.

 The data used in these  scenarios are discussed hi the next section.

 Data  Inputs         '

        The exposure  scenarios were constructed using a mix of central tendency and high-end
 values.   The central tendency  values were used  for the following parameters: background
 maternal intake, proportion of pollutant stored in fat, fat content of breast milk, and absorption
 rate for ingested pollutants.  The remainder of the parameters were set to then: high-end values.
 Sources for the input values are discussed below.

        General Inputs. Exhibit 4-19 shows the general (i.e., not pollutant-specific) inputs used
 to  calculate  exposure to  infants through  breastfeeding.  The values for many of the input
 parameters were taken  from Smith (1987) and U.S. EPA (1994b).   The fat  content of milk
 (0.04) and the ingestion rate of milk come from information reported in Smith (1987).  A study
 of British children found mean intakes hi the first 7 to 8 months that ranged from 677 to 922
 ml per day (Whitehead  and Paul, 1981 as cited in Smith, 1987).  A  value of 0.9 L is used in
 this assessment; assuming the density of breast milk is approximately that of water, 0.9 L is
 equivalent to 0.9 kg.  Smith (1987) presents two studies that estimate the percent of maternal
 body weight that is fat.  One study estimated a fat content of about 33% (Timson and Coffman,
 1984,  as cited hi Smith, 1987), and a second study found a reduction from a mean of 28% to
 26.3% during four months of lactation (Butte et al.,  1984, as cited in  Smith, 1987).  Based on
 these data, the current assessment uses 0.3.as the proportion of maternal weight that is fat.

       •The exposure duration and infant body weight over the exposure period differ between
the two scenarios.  This  analysis uses exposure durations of one or two years.  Because the body
weight of an infant differs for these two exposure durations, the current analysis uses different
infant body weights for each exposure duration.  For a one-year exposure duration, an infant
body weight of 9.1 kg (an average for babies 6 to 11 months old) is used to represent an average
body weight during the first year. For the two year exposure duration, a body weight  of 11.3
kg (the average for 1 year old babies) is used as the average body weight over the first two years


                                         4-98

-------
  of life.  Both values are taken from the National Center for Health Statistics (1987) (cited in
  U.S. EPA, 1994b).

         The appropriate choice of averaging time for these less-than-lifetime exposures depends
  on the health endpoint assessed. In this analysis, different averaging times are used to estimate
  the daily dose.  First, the averaging time is set equal to the exposure duration (Scenario 1) to
  obtain an estimate of daily dose for the period during  which exposure occurs.  Such an estimate
  may be appropriate to evaluate health effects (such as developmental effects) that can occur from
  short-term exposures (U.S. EPA,  1994b).  (At this time, corresponding health risk values are
  not available. Therefore, this calculation is only carried to the point of estimating exposure )
  Second, this analysis also uses an averaging time of 70 years (Scenario 2) to calculate a lifetime
  average  daily dose (LADD) to correspond with exposure duration assumed for cancer potency
  estimates.
                                     EXHIBIT 4-19
    General Input Parameters to Estimate Exposure to Pollutants through Breastfeeding
   Parameter values common to all three scenarios:
  fz: proportion of mother's weight that is fat (dimensionless)
                              0.3
  •f3: proportion of fat hi breast milk (dimensionless)
                              0.04
  IM: ingestion rate of breast milk (kg/day)
  ==========^=^=^====^=^==—
  Parameter values that differ among scenarios:

  ED: exposure duration (yr)
scenario 1
scenario 2
                              0.9
                                                                         1
                                                                         2
         '- infant's average body weight (kg) scenario 1
                                          scenario 2
                              9.1
                             11.3
  AT: averaging time (yr)
scenario 1
scenario 2
 1
70
       Pollutant-Specific Inputs. For this pathway, only pollutants with a log Kow value greater
than five were evaluated. Other pollutants were not considered sufficiently lipophilic to warrant
further analysis.  Of the Round Two candidate pollutants, only three-dioxins and dibenzofurans
coplanar PCBs and bis (2-ethylhexyl) phthalate (BEHP)-have log K^ values of five or greater
(see Exhibit 4-17 in Section 4.2.12).  After further research, infant exposure to BEHP through
breastfeeding was not evaluated because the biological half-life of BEHP in humans is  less than
one day. Schmid and Schlatter (1985) estimated the urinary elimination half-life to be  12 hours
and concluded that accumulation of BEHP in the human body was  unlikely  Sjoberg et al
                                         4-99

-------
 (1985) determined that BEHP levels in the human body decline with a half-life of 10 hours.
 Based on these data, infant exposure to BEHP through breastfeeding did not require further
 consideration.  Therefore, only dioxins and furans and coplanar PCBs are considered for this
 pathway.

       There are five pollutant-specific parameters  used to estimate exposure through this
 pathway: maternal background exposure from other sources; maternal exposure from the relevant
 sewage sludge pathways; percentage of pollutant ingested by the mother that is stored in her fat;
 the half-life of the pollutant in the adult human body; and the percentage of pollutant ingested
by the infant that is absorbed. The pollutant-specific inputs for these pollutants are described
below; Exhibit 4-17 summarizes the pollutant-specific input values and the references for these
values.

      Maternal exposure from other sources.  For dioxins, a background exposure of
       119 pg/day is assumed. This value is derived from environmental concentration
      data collected hi rural, pristine, and urban areas not  thought to be affected by
      local sources (U.S. EPA, 1994b).  Dividing this value by the standard adult body
      weight of 70 kg yields 1.7 pg/kg-day.   A similar value for coplanar PCBs  was
      not found;  therefore, only incremental risk from exposure above background can
      be assessed for coplanar PCBs.

      Maternal exposure from sewage sludge pathways.  For the estimate of maternal
      exposure from the relevant sewage sludge pathways, the results of the exposure
      assessments for pathways  1, .2, 4, 5,  12,  13 and 14 (described  hi previous
      sections) were considered simultaneously as the source of maternal body burden.

      Percentage of pollutant ingested by the mother stored in her fat. The proportion
      of ingested  dioxins stored hi fat (0.9) is taken from Smith (1987) (as cited in U.S.
      EPA, 1994b).  Coplanar PCBs are assumed  to behave in  a  similar manner.
      Distribution studies of PCBs demonstrate that the adipose/plasma partition ratio
      for  PCBs ranged between  185/1 and 210/1 depending on the PCB  involved
      (Brown and Lawton,  1984). Based on these data  (and  assuming some PQBs are
    •  stored in other body tissues besides adipose tissues and plasma), it is assumed that
      90 percent of the ingested coplanar PCBs are stored in fat.

      Biological half-lives.  U.S. EPA (1994b) presents different half-lives for 2,3,7,8-
      TCDD in humans, from 5.8 years to 7 years.  For this analysis, a half-life'of 7
      years is used as a conservative estimate.

      For PCBs, Yakushiji et  al. (1978) reported an approximate half-life of 8 months.
      In an analysis  of exposure  to fish, contaminated  by PCBs hi the Great Lakes,
      Anderson and Amrhein (1993) assumed  a half-life of one year, based  on their
      review of the  literature, although it should be noted that longer half-lives were
      estimated for particular .PCB mixtures (up to a suggested half-life of 10 years for
      congener #153).   For  this  assessment,  a half-life of one year was used for
      coplanar PCBs.
                                       4-100

-------
         Percentage of pollutant ingested by the infant that is absorbed.  Ninety percent
         of ingested dioxins were assumed to be. absorbed by the infant (Smith  1987 as
         cited in U.S. EPA, 1994b).  For PCBs,  studies of monkeys (Allen et al  1974)
         and ferrets (Bleavins et al.,  1984) demonstrated  .90% and 85.4% absorption
         efficiencies, respectively.   Based  on the data for monkeys, 90% absorption
         efficiency in humans was assumed for.coplanar PCBs.
                                       EXHIBIT 4-20
      Pollutant-Specific Input Parameters to Estimate Exposure to Pollutants through
                                        Breastfeeding
                 Pollutant
 Maternal
Background
•  Intake
(mg/kg-day)
Proportion
    of
 Pollutant
 Stored in
Proportion
of Ingested
 Pollutant
 Absorbed
Half-Life of
Pollutant in
 Adults (hj)
   Dioxins and Dibenzofurans
1.7xlO-9(I>
                                                        0.9®
                            0.9®
                                                                                7 years(1)
   Polychlorinated biphenyls (coplanar)
 'U.S. EPA (1994b).
 2Smith (1987).
 3Brown and Lawton (1984).
 "Allen et al. (1974).
 5Anderson and Amrhein (1993).
                0.9(3>
                                                                     0.9(4>
Example Exposure Calculations for Pathway 15

       The following example calculates the exposure of infants to dioxins and dibenzofurans
in breast milk  First, the maternal intake of dioxins in sewage sludge from agricultural pathways
i, 2, 4,  5,  12,  13, and  14 (msludge diolij!s) is calculated using  the methods  discussed hi the
corresponding sections. The value of msludgt_ ^ is 1.4 x 10'9 mg/kg-day. Equation 4-78 is then
used to calculate  the concentration of dioxins hi milk fat:
                                          4-101

-------
         C         -
           mittfat, dioxins
                       (1.7xlQ-9mg/kg-day
                                        2555days  -0.9
                                              0.693  • 0.3
                    = 3.5x20-5mg/kg
 where:
        1.4xlO-9

        2555
        0.9

        0.693
        0.3
         , / (maternal  intake of dioxins from sources other than
 sewage sludge) from Exhibit 4-20,
 msiadge.j (maternal intake of dioxins from sewage sludge exposure
 pathways  1, 2, 4, 5, 12, 13, and 14),
 hj (half-life of dioxins in adults) from Exhibit 4-20,
' /7i j (proportion of ingested dioxins that  is stored in fat) from
 Exhibit 4-20,    .
 ln(0.5), to convert the half-life of dioxins  into a rate, and
 /2  (proportion of mother's weight that is fat) from Exhibit 4-19.
       Exposure to the infant under Scenario 2 can then be calculated using Eq. 4-79:
                     diorins
=  3.5xlQ-5mg/kg  • 0.04 • 0.9 • 0.9kg/day • 2yr
                  11.3kg • 70yr

= 2.SxlO -9mg/kg -day
•where:
       3.5xlO'5

       0.04
       0.9

       0.9
       2
       11.3

       70
           (concentration of dioxins in maternal milk) calculated
 above,
f3 (proportion of fat hi breast milk) from Exhibit 4-19,
ft.j (proportion of ingested dioxins that is absorbed) from Exhibit
 4-20,
 IM (ingestion rate of breast milk) from Exhibit 4-19,
 ED (exposure duration) from Exhibit 4-19 for Scenario 2,
 BWinfant  (average body weight of the  infant during the exposure
 period)  from Exhibit 4-19 for Scenario 2, and
AT (averaging time) from Exhibit 4-19 for Scenario 2.
                                         4-102

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  4.3    SURFACE DISPOSAL EXPOSURE METHODOLOGIES

         Under the surface disposal practice for sewage sludge, humans can be exposed to
  pollutants volatilizing or leaching from sewage sludge placed in either a monofill or a surface
  impoundment. Humans can either inhale air or ingest groundwater containing pollutants.  In
  this section, the modeling prototypes for monbfills and surface impoundments are defined.
  The methods used to model volatilization and leaching from the prototypes are then presented.

  4.3.1  Definitions of a MonofiU and a Surface Impoundment

         The  monofill prototype is a sewage sludge-only trench fill. Only de-watered sewage
  sludges with solids content greater than or equal to 20 percent are assumed to be suitable for
  placement in a monofill, and the sewage sludge  often is mixed with a bulking agent (e.e
  soil)  to increase solids content.  Operating  procedures assumed include daily" cover  which
  reduces odors and provides  vector control,  and  a final cover placed on the monofill after
  closure.

        The surface impoundment prototype  receives a continuous inflow of sewaee sludge
  with a low solids content (between two and five percent).  A vertical outflow pipe maintains
  the surface liquid  level at a constant height,  and liquid is assumed to leave the impoundment
  both in the outflow (possibly for return to the treatment works) and in seepage through the
  floor of the impoundment.  Over time, paniculate settling occurs and a denser layer of "solids
  accumulates  on the floor of the impoundment. Eventually, this layer of solids reaches the top
  of the impoundment and no further inflow is possible.  Upon closure, the sewage sludge is
  left permanently in place and remains uncovered.

        One key difference between the surface impoundment and monofill prototypes is that
 the active surface impoundment is assumed to contain significantly more liquid than the active
 monofill.  Seepage through the floor of the surface impoundment is expected to be greater
 than seepage from the monofill, and may be sufficient  to sustain a local moundiiuTof the
 underlying water table.  The surface layer of the impoundment also  is assumed to"be in a
 liquid  state over the active lifetime  of the  impoundment.   The volatilization of  organic
 pollutants from this liquid layer is expected to  differ from that predicted for a monofill which
 is assumed to contain a higher percentage of solids and to receive a daily, and eventually a
 permanent, cover,                                                 •

 4.3.2  Methods for the Monofill Prototype

 Method for Mass  Balance

       Pollutant mass is assumed to  enter the monofill through daily deposits of sewage
 sludge  and to be  removed through degradation,  leaching,  and volatilization   Rates  of
pollutant loss  are assumed to be first-order (that is, proportional to the residual concentration
ot pollutant in the monofill); mass balance calculations begin  by estimating first-order loss
coefficients for each competing loss process.
                                      4-103

-------
        Pollutant Losses Through Leaching. A coefficient for the rate of pollutant loss to
  leaching is calculated by assuming  that pollutant mass hi a filled monofill active sewage
  sludge unit is partitioned at equilibrium between dissolved and adsorbed phases.  Based on
  mathematical relationships  presented hi Section 4.2.14, the  concentration of  pollutant
  dissolved in water within the monofill  can be estimated from the total concentration of
  pollutant within the monofill:
 where:
        Cw     -     concentration of dissolved pollutant  hi  water-filled  pore space  of
                     sewage sludge/soil hi monofill (kg pollutant/m3 porewater),
        C,     =     total concentration of pollutant hi bulk sewage sludge/soil in monofill
                     (kg pollutant/m3 total bulk soil volume),
        BDma  =     bulk density of sewage sludge/soil (kg soil/m3 total bulk soil volume),
        Kd     =     soil-water partition coefficient (L water/kg. soil), .
        #u-     =     water-filled porosity (dimensionless),
        H     =     Henry's Law constant (dimensionless),
        6*      =     air-filled porosity (dimensionless), and
        10-3    =     constant to convert (L) to (m3).


        The dimensionless Henry's Law constant can be calculated by:
                                   H  = -  -                            (4_81)
                                        R • T  • ICT3

where:                                     .
       H     =     Henry's Law constant (atm-m3/mol),
       R     =     gas constant (L-atm/mol-K),
       T     =     temperature (Kelvin),  and
       10'3    =     constant to convert (L) to (m3).

       For  an  arbitrary  unit   concentration of pollutant  in  the  sewage  sludge/soil
(1 kg pollutant/m3 sewage sludge/soil),  a flux of pollutant mass leaching from the monofill
can be calculated  as  the product of net recharge (NR) and the expected concentration of
pollutant in leachate.  Moreover, with a unit concentration of pollutant,  the mass of pollutant
beneath one square meter of surface is equal to the volume of sewage sludge/soil beneath that
area.   This volume can be expressed as kg pollutant/m2 area/m depth  of the monofill.  As
discussed hi Section 4.2.14, the  estimated flux of leaching pollutant is  divided by mis mass
to derive a first-order loss coefficient for leaching:,
                                        4-104

-------
                                              7VR
  where:
        KIK    =     loss rate due to leaching of the pollutant from monofill (yr1),
        NR    =     annual recharge to groundwater beneath the monofill (m recharge/yr),
                      and
        dmf    =     depth of a monofill active sewage sludge unit (m).


        Pollutant Losses Through Volatilization. Rates of volatilization from a filled active
  sewage sludge unit in a monofill will vary according to whether a cover layer of soil has been
  applied.  Each active sewage sludge unit in the monofill  is assumed to contain uncovered
  sewage sludge for a few hours on each of the days it receives sewage sludge.  Following each
  placement, a temporary cover  layer of soil  is applied.   Once the monofill's capacity is
  exhausted, a thicker permanent cover of soil is applied to the entire monofill (U.S. EPA,
  1986d). A time-weighted average of emission rates with and without cover is used, therefore.
  to describe the average rate of volatile emissions for an  individual active sewage sludge unit
  in the monofill.  The fraction of the  monofill's active lifetime that a typical active sewage
 sludge unit will be uncovered is calculated as:
                        •   : '  '       ' /. - 7=;  .   . '                          (4-83)

 where:
       fm     =     fraction of monofill's active lifetime that a typical active sewage sludge
                     unit contains sewage sludge without soil cover (dimensionless),
       tm     =     tune that a typical active sewage sludge unit contains uncovered sewage
                     sludge (yr), and                                                "
       LF    -     active lifetime of monofill (yr).
       Some monofill active  sewage sludge units will  be filled  early  in  the monofill's
operation, others nearer to the monofill's closure. The average monofill active sewage sludge
unit is assumed to contain sewage sludge for half the active lifetime of the monofill  The
fraction of the monofill's active lifetime that such a unit  will contain sewaee sludge that is
rr\\rf*rt*ri ic-                         ••                                  °      °
covered is:
                                       4-105

-------
                                     fco    2   fun                             ^


 where:
       /„     =     fraction of monofiU's active lifetime that typical active sewage sludge
                     unit contains sewage sludge with temporary soil cover (dimensionless"),
                     and
        1A     =     fraction of monofill's active lifetime that typical active sewage sludge
                     unit contains sewage sludge (dimensionless).

       A time-weighted average flux of pollutant emissions from a typical monofill active
 sewage sludge unit is calculated from equations describing emissions from a unit with and
 without soil cover. According to Environmental Science and Engineering (1985) as discussed
 in U.S. EPA (1986d), emissions from an uncovered landfill cell can be described by:


                                    0.17 u 0.994(r-293) Ca.
 where:                                                                             ~       	
       
-------
         Equations 4-85 and 4-86 require an estimate of the concentration of pollutant in air-
  filled pore space within the active sewage sludge unit.  As discussed in Section 4.2.14, this
  concentration can be related to the total concentration of pollutant hi sewage sludge/soil as:

                                             10-3    8M                          (4-87)
                                                          6_
                                         H          H
  where:    .             .    .
        Ca     =     concentration of gaseous pollutant hi air-filled pore space of monofill
                      (kg pollutant/m3 ah:),
        C,     =     total  concentration of pollutant hi bulk sewage sludge/soil in monofill
                      (kg pollutant/m3 total bulk soil volume),
        KA    .-   '  soil-water partition coefficient (L water/kg soil),
        B.Dmix  --     bulk  density of sewage sludge/soil (kg soil/m3 total bulk soil volume),
       . H     =     Henry's Law constant (dimensionless),
        #w     —     water-filled porosity  (dunensionless),
        0a     =     air-filled porosity (dimensionless), and
        10'3    =     constant to convert (L) to (m3).


        Estimated pollutant fluxes from an uncovered and temporarily covered monofill active
 sewage sludge unit are combined  to derive a tune-weighted average pollutant flux  from a
 monofill  unit during the monofilFs active lifetime:


            '  .                  £« =  4unfun  + Icofco              .           (4'88)

 where:
        qac    =     time-weighted average pollutant flux from typical monofill unit over the
                     active lifetime of the  monofill (kg pollutant/m2 unit-sec).

        For a  unit concentration  (C,=l kg  pollutant/m3 sewage sludge/soil) of pollutant in
 sewage sludge/soil, the mass of pollutant  beneath one  square  meter of  monofill surface
.(kg/m2) is equal  to the depth of the monofill (m). Therefore, converting the estimated loss
 rate (kg/nr-sec)  into a first-order loss  coefficient  (yr1) requires division by depth and
 adjustment of units from seconds to years:
                                        4-107

-------
                                          qnr 3.16xl07
                                    K   = ?£. -                           (4-89)
                                             "
  where:
        KM          • -     loss rate of pollutant  due to volatilization during monofill's
                             active operation (yr1), and
        3.16xl07     =     constant to convert units from (sec"1) to (yr1).

        Fraction of Pollutant Loss to Each Pathway.  Estimated coefficients for losses to
  volatilization and  leaching are  combined  with assumed  rates of  degradation  to yield  a
  "lumped" coefficient describing pollutant loss through all three pathways during the monofill's
  active lifetime:


                                X  =KUC  + Zva+KtUg                          (4-90)

 where:             .
        K,a     =     total loss  rate  of pollutant  due  to leaching,  volatilization,  and
                      degradation during monofiU's active  operation (yr1).


        The fraction of pollutant  loss attributable to each  individual process during the
 monofill's active lifetime  is:
                        4-=     /«»=     /*,  =                      (4-91)
                               A«z           *M           ' Kv

where:                                                           .
       /to     =     fraction  of total pollutant  loss  during monofill's active  operation
                     attributable to leaching (dimensionless),
       fw     =     fraction  of total pollutant  loss  during monofill's active  operation
                     attributable to volatilization  (dimensionless), and
       ftu,     =     fraction  of total pollutant  loss  during monofill's active  operation
                     attributable to degradation (dimensionless).

       The fraction of total loading lost within the monofill's active lifetime is calculated
numerically from the lumped rate of pollutant loss, assuming a time  step of one year and a
unit pollutant loading of one kg/ha-yr:
                                        4-108

-------
                            Mt =  0                      (r=0)
                                                                                   (4-92)
  The fraction of total pollutant lost during a monofill's active lifetime can then be calculated
  as:

                                 '           ---                                 (4-93)
                                    .
                                    ac       1  - LF

  where:            •               "              .     •                    .
        /„,.      =     fraction of  total  pollutant  lost  during monofill's  active  lifetime
                      (dimensionless),
        Mff    =     mass of pollutant  in sewage sludge/soil at end of monofill's  active
                      lifetime (kg pollutant/ha), and
        1       =     annual unit loading of pollutant (kg/ha-yr).

        Once the monofill's capacity is exhausted, a permanent cover layer of soil is applied
 to its surface. This permanent cover reduces the rate of volatilization, changing both the total
 rate of pollutant loss and the  relative fraction of that loss attributable to  volatilization,
 leaching, or degradation.  Based on the  increased thickness of cover, an estimated rate of
 volatilization from  the -inactive monofill  (£„-) is calculated with Eqs. 4-86 through 4-88 by
 setting /„„ to zero.  Rate coefficients for loss to leaching and degradation are assumed to be
 unaffected by soil cover, so the lumped rate of loss for the inactive monofill is described by:


                                 K« ' Kuc  + *v, + K^                          (4-94)

 where:
        Kti     =     total loss rate of pollutant from inactive monofill (yr1),  and
        Kvi     =     loss rate of pollutant due to volatilization from inactive monofill (yr1).


 The fraction of loss attributable to volatilization is calculated as:

                                              j£-
                                       fvi = -/                                (4-95)
                                              &ri

where:
       /"      =     fraction  of  total  pollutant loss from inactive monofill attributable  to
                     volatilization (dimensionless).

As will be discussed below, these fractions and the lumped rate coefficients for pollutant loss
are used to estimate pollutant concentrations in air and groundwater near the site.
                                         4-109

-------
  Method for Groundwater Pathway

        Upon completion of the mass balance calculations described above, two additional
  steps are used to calculate the concentration of each pollutant hi groundwater:

        1)     Determine the concentration of pollutant hi leachate from the bottom of the
               monofill.

        2)     Use mathematical models for the transport of pollutant through the unsarurated
               and saturated soil zones to estimate expected concentrations of pollutants in
               groundwater.  .

        With the mass balance calculations, the total rate at which a pollutant is lost from the
 monofill, and the fraction of that, loss attributable to leaching, are estimated.  The amount of
 time that would be required to deplete the entire mass of pollutant placed in a monofill at the
 maximum predicted rate of loss for that pollutant is estimated. This approach is conservative
 because using higher estimates for pollutant flux leaving the monofill will yield a higher
 estimate of pollutant concentrations at the well.

        For monofills, the rate of maximum total pollutant loss  (hi kg/yr) will occur in the
 year immediately following the last placement of sewage sludge,  because the total mass of
 pollutant at the site reaches its peak at that tune. As explained in Appendix C, this peak rate
 of loss could  be maintained for a maximum length of. tune described by :
 where:
       TP    =     duration of "square wave" for approximating the loading of pollutant
                     into me unsaturated soil zone (yr).

       This result is combined with the estimate of the fraction of totaf pollutant loss through
 leaching for a conservative  estimate of the average flux of pollutant leaching from  the
 monofill:
                                                                               (4-97)


where:                         ,                                        .   .
           j        =     annual average flux of pollutant j leaching from the monofill
                           (kg pollutant/ha-yr),
       Cj            =     concentration of pollutant j in sewage sludge (mg pollutant/kg
                           sewage sludge),
       sc           =     estimated mass of sewage sludge contained  in one hectare of
                           completed monofill (kg/ha), and
                                        4-110

-------
         icr
                      constant for convening units from (mg/ha-yr) to (kg/ha-yr).
         Because sewage sludge is often combined with soil to increase solids content when
  placed  in a monofill,  the volume (and mass) of sewage sludge in the monofill is only  a
  fraction of the total volume of the monofill.   Therefore, the dry mass of sewage sludge
  contained in one hectare of filled monofill is calculated by multiplying the monofiH's depth
  by the fraction of its volume containing sewage sludge and by the mass of solids in one cubic
  meter of sewage.sludge:
 where:
                                    = dmffsl BDsludge
                                                                        (4-98)
                             BD
 and:
        BD
           sludge
       L

       Psl

       PH-
       Jsol

       io*.
                                sludge
                                                                       (4-99)
                     bulk density of sewage sludge (kg sewage sludge/m3 sewage
                     sludge),
                     fraction  of monofill's  volume  containing  sewage sludge
                     (dimensionless),                                 "-''.'' ~
                     particle density of sewage sludge (kg sewage sludge/m3 sewaae
                     sludge),
                     density of water (kg water/m3 water),
                     fraction of solids in sewage sludge , (kg  solids/kg  sewaee
                     sludge), and
                     constant for converting units from (kg/m2) to (kg/ha).
       Next, dividing this estimated flux by the assumed net recharge and adjusting units
yields the estimated average concentration of pollutant in leachate:
                                         0.1 FA
                                   'lecj
                                                lecj
                                             NR
                                                                            (4-100)
where:
c

0.1
                    average concentration of pollutant/ in water leaching from the monofill
                    site (mg pollutant/L water), and
                    constant to convert from (kg/ha-m) to (mg/L).
       The next step is to relate the leachate concentration to the expected concentration of
pollutant in drinking water wells near the site.  Two mathematical models are combined to
calculate an expected ratio between these two concentrations.  The Vadose Zone Flow and
Transport finite element module (VADOFT) from the RUSTIC model (U.S. EPA, 1989d,g)
is  used to estimate flow and transport through the  unsaturated  zone,  and the AT123D
                                       4-111

-------
   ana
   zone.
tlytical model (Yeh,  1981) is used to estimate pollutant transport through the saturated
le.
         VADOFT allows consideration of multiple soil layers, each with homogeneous soil
   characteristics. Within the unsaturated zone, the attenuation of organic pollutants is predicted
   based on longitudinal dispersion,  an estimated retardation coefficient derived from  an
   equilibrium soil-water partition coefficient,  and  a first-order rate of pollutant degradation.
   The input requirements for the unsaturated zone module include various site-specific and
   geologic parameters and the leakage rate from the bottom of the monofill. It is assumed that
   the flux  of pollutant mass into the  top of the unsaturated zone beneath a monofill  can be
   represented  by results from the mass-balance  calculations described above.  Results from
   analysis of the unsaturated zone give the flow velocity and concentration profiles for each
  pollutant. These velocities and concentrations are evaluated at the water table, converted to
  a mass flux, and used as input to the AT123D saturated zone module.

         The flow system in the vertical column is solved with VADOFT, which is based on
  an overlapping representation of the unsaturated and saturated zones.  The water flux at the
  soil/liquid interface is specified for the bottpm of the monofill, which defines the top of the
  unsaturated zone in the model. In addition, a constant pressure-head boundary condition is
  specified  for the bottom of the unsaturated zone beneath the monofill.  This pressure-head is
  chosen to be consistent with the expected pressure head  at the bottom of the saturated zone
  without consideration of the added flux  seeping from sewage sludge  in  the  monofilf
  Transport in the unsaturated  zone is  determined  using  the Darcy  velocity and  saturation
  profiles from  the  flow simulation.    From  these,  the  transport  velocity profile can be
  determined.

        Although limited to one-dimensional flow and transport, the use of a rigorous  finite-
 element model in the unsaturated zone allows consideration of depth-variant physical and
 chemical processes that would influence the mass flux entering the saturated zone. Among
 the more  important of these  processes are advection (which is a  function of the Darcy
 velocity, saturation, and porosity), mass dispersion, adsorption of the leachate onto the  solids
 phase, and both chemical and biological degradation.

        To represent the variably saturated soil column beneath the floor of the  monofill  the
 model  discretizes the column  into  a  finite-element grid consisting of  a series . of one-
 dimensional  elements connected at  nodal  points.   Elements can be assigned  different
 properties for the simulation of flow in a heterogenous system.  The model generates the grid
 from user-defined zones; the user defines the homogeneous properties of each zone, the zone
 thickness, and the number of elements per zone, and the code automatically divides each zone
 into a series of elements of equal length. The governing equation is approximated using the
 Galerkm finite  element method and  then  solved iteratively  for the dependent variable
 (pressure-head), subject to the chosen  initial  and boundary conditions.  Solution of the series
 of nonlinear simultaneous equations generated by the Galerkin scheme is accomplished by
 either Picard  iteration,  a  Newton-Raphson  algorithm  or a  modified  Newton-Raphson
 algorithm.  Once the finite-element calculation converges,  the model yields estimated values
 for all the variables at each of the discrete nodal points. A detailed description of the solution
scheme is found in U.S. EPA (1989g).
                                        4-112

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        One-dimensional, advective-dispersive transport is estimated with VADOFT based on
  the estimated mass flux of pollutant into the top of the soil column, and a zero concentration
  boundary condition at the bottom of the saturated zone.  As discussed earlier, sewage sludge
  is assumed to be deposited in the monofill for 20 years, followed by an inactive period in
  which pollutant is depleted from the monofill by leaching, volatilization, and degradation.
  To simulate potential contamination of groundwater,  the  loading of pollutant into  the
  unsaturated zone beneath the monofill is "linearized" into a pulse of constant magnitude (TP)
  to represent the maximum annual loss of pollutant (hi kg/ha-yr) occurring over the 300-year
  simulation period modeled.  The duration of that pulse is calculated so .that pollutant mass is
  conserved.

        As  in calculations for the unsaturated  zone, degradation of organic pollutants  is
  assumed to be first-order during transport through the aquifer.  Speciation and complexation
  reactions are  ignored for metals, leading to the possible over- or under-estimation of expected
  concentrations  of  metals  hi  groundwater at the  location  of a receptor well.   Detailed
 descriptions of the AT123D model are provided by U.S. EPA (1986d) and by Yeh (1981) and
 will not be repeated here.  In general, the model provides an analytical solution to the basic
 advective-dispersive  transport equation.  One advantage of AT123D is its flexibility: the
 model  allows the user up to 450  options and is capable of  simulating a "wide  variety  of
 configurations of source release and boundary  conditions.   For the current  application,
 AT123D uses the source term and other  input parameters  to predict  concentrations  of
 pollutant (Cwel)  within 300 years in a receptor well at the downgradient edge of the site~'s
 property boundary.

 Method for Volatilization Pathway

       Two steps provide an estimate of the concentration of a volatilized pollutant in air near
 the monofill:                                    ••„.•'

       1)     Use the mass balance calculations summarized above to determine the mass  of
              pollutant expected to volatilize from the monofill within a period equivalent to  '
              a human lifespan, and                .

       2)     Use a simplified version of the Industrial Source Complex Long Term Model
              (ISCLT) to model the transport and dispersion of pollutant in ambient air near
              the monofill.

       Results from the mass  balance calculations are used to  estimate the fraction of total
pollutant mass expected to volatilize from the monofill within an expected human lifetime
(assumed to be 70 years), which spans both the active and inactive phases of the monofill's
operation:
                                        4-113

-------
                                                   -"-^                 (4-101)

  where:
        jta    =     fraction of  pollutant mass that  volatilizes  over a human lifetime
                      (dimensionless), and
        LS    =     average human lifetime (yr).
        Next, this fraction is multiplied by the total mass of pollutant placed in the monofill,
 and divided by the time of release to calculate "an average flux:
                     •                 .         L*J

 where:       •
             j         =     annual average flux of pollutant./ volatilizing from the monofill
                            (kg pollutant/ha-yr),
                      =     constant to convert units from (mg/ha-yr) to (kg/ha-yr), and
        Cj         ,    =     concentration of pollutant j in sewage sludge (mg pollutant/kg
                            sewage sludge).                                       .  .  -

        The next step is to relate releases of volatilized pollutant to the expected concentrations
 in ambient air.  The model used to simulate transport  of pollutant from a monofill site is
 described by U.S.  EPA (1986d) and is based on equations provided by Environmental Science
 and  Engineering (1985).  These equations are simplifications of equations used in ISCLT
 The exposed individual is assumed to live at the downwind property boundary of the monofili
 site.  A source-receptor ratio is calculated to relate the. concentration of pollutant in ambient
 air at that individual's location (g  pollutant/m3 air)  to the rate at which that pollutant is
 emitted from the monofill (g pollutant/m2 monofill  area-sec):
                                  = 2.032     —                            (4-103)
                                           (r'+xy)uoz

where:                                                                           •
       SRR   =     source-receptor ratio (sec/m),
       2.032  =     empirical constant,
       Amono   =     area of monofill (m2),
       V,      =     vfrtical term for dispersion of pollutant in air (dimensionless),
       r'      =B     distance from the monofill's center to the downwind edge (m),
      xy      -     lateral virtual distance  to the monofill (m),
       u       -     average wind speed (m/sec), and
       or.      =     standard deviation of the vertical distribution of pollutant concentration
                    in air (m).
                                       4-114

-------
         The vertical term (v) is a function of source height, the mixing layer height, and oz.
  Under stable conditions the mixing layer height is assumed to be infinite, and for a pollutant
  release height of zero,  v=l.  The lateral virtual distance is the distance from a virtual point
  source to the monofill,  such that the angle 6 subtended by the monofill width is 22.5°. This
  distance is calculated as:
                                        ^
                                          Amono cot -                         (4-104)
        The distance from the center of the land application site to the downwind edee  is
  calculated assuming a square monofill:                                  -
                                                                               (4-105)
        The standard deviation of the vertical distribution of concentration (a.) is defined by
 an atmospheric  stability class and the distance from  the center  of the monofill  to the
 downwind edge.  Exhibit 4-18 provides values for two parameters, a and fe,  for a range of
 distances under stable  atmospheric conditions.   Based on values from this  table, an
 appropriate value of a. is calculated as:


                                       oz = a xb                               (4-106)

 where:

                                     * = 10-3 -r1                   '          (4-107) .

 and:  •

       x             =     distance from the  center of the monofill to the downwind edge
                           (km), and
       10"3           =     constant to convert (m) to (km).

       This result is combined with the estimated average flux of pollutant to predict the
 average concentration of pollutant in ambient air over this period:
                                                  0.00317          ,          (4-108)

where:                                                          '                   .
       C<*r.j          —     average concentration of pollutant j hi ambient air  at  the
                           downwind edge of site (fig pollutant/m3 air), and
       0.00317       =     constant to convert (kg/ha-yr) to G*g/m2-sec).

                                        4-115

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  4.3.3  Methods for the Surface Impoundment Prototype

         The methods for estimating exposure for surface impoundments are similar to those
  described in Section 4.3.2 for monofills.  As with monofills, a mass balance of pollutant
  losses from the surface impoundment is calculated first.

  Method for Mass Balance

         Pollutants hi sewage sludge are assumed to enter the surface impoundment through
  continuous inflow, and to be removed through four general processes:

         1)     degradation   within  the  surface  impoundment  (e.g.,  photolysis,
               hydrolysis, or microbial decay);

        2)     transportation out of the surface impoundment by seepage through the
               floor of the impoundment;

        3)     outflow (possibly for return to the treatment works); and

        4)     volatilization from the liquid surface of the impoundment.

        The model for describing these four processes in this analysis is adapted from a two-
 layer model suggested by Thomann and Mueller (1987) for modeling toxic substances in a
 lake.  For the water column of a lake, those authors consider the inflow and outflow of
 pollutant,  diffusive exchange between the solids  layer and the  water column, degradation
 volatilization, the settling of paniculate toxicant from the water column to the solid  and the
 re-suspension of particulate from the solids layer to the water column.  For the solids layer
 they consider diffusive exchange with the water column, decay processes, particulate  settling
 from the overlying water column, re-suspension from the solids to the water column, and loss
 of toxicant from the solids due to net sedimentation or burial.

       A similar, two-layer model is used for surface impoundments.  The "liquid" layer
 begins at the surface and has the same  average  solids content as inflow to the surface
 impoundment; the "solid" layer beneath has a higher solids content.  Although a gradient of
 solids concentrations  is likely to form in an actual impoundment, each layer is idealized as
 homogeneous for both solids and pollutant concentrations.

       Thomann and Mueller provide explicit equations for predicting settling velocities for
particulates and  rates  of diffusive  exchange between  the two layers,  but  the present
methodology derives simpler equations by assuming the  solids layer will eventually  reach the
surface  of the impoundment and outflow contains negligible concentrations of suspended
solids. All loss processes are approximated as proportional to pollutant concentration; i.e.,
loss  rates at any time are  proportional to the current concentration  of pollutant  in the
impoundment.                    .
                                       4-116

-------
        Two additional simplifying assumptions are made:

        1)     Concentrations  of pollutant  within each  layer are assumed to  be at
               steady-state and to be partitioned at equilibrium between adsorbed and
               dissolved phases..

        2)     Rates of pollutant transfer and loss when the impoundment is half-filled
             .  with solids are assumed to be typical of the surface impoundment both
            .   before and after it fills with sewage sludge.

        If rates of loss to effluent, volatilization, seepage, and degradation are all proportional
 to pollutant concentration,  the maximum total  rate of loss  will  occur if equilibrium
 concentrations are attained.  Moreover, after the continuous placement of sewage sludge in
 the surface impoundment is  terminated, the rates at which pollutant is lost to  seepage and
 volatilization should decline.  By assuming that equilibrium conditions represent the entire
 (active and inactive)  lifetime  of the surface impoundment, this methodology, probably
 overestimates  rates of pollutant  loss  through seepage and  volatilization,  leading  to
 conservative estimates of risks.

       Liquid  Layer.  The concentration of pollutant in the inflow of the impoundment (Q
 and  in the liquid  layer (C,)  are assumed to remain   constant throughout  the  surface
 impoundment's active lifetime.   The partitioning of pollutant in the liquid layer is described
as:
                                                                 + DVC,     (4-109)

where:            .                                  '.        •
       Qi     =•    rate  at  which  sewage sludge enters the impoundment (m3 sewage
                    sludge/sec),
       C,     =     concentration   of  pollutant   in  inflow   to   the  impoundment
                    (kg pollutant/m3 sewage sludge),
       Qo     -     rate at which outflow  leaves the impoundment, possibly  for further
                    treatment (m3 sewage sludge/sec),
      fa     =     fraction  of  total  pollutant  in  liquid  layer  that   is  dissolved
                    (dimensionless),
       C,     =     total concentration of pollutant (adsorbed and dissolved) in liquid layer
                    of impoundment (kg pollutant/m3 liquid layer),
      Kdegi   =     anaerobic rate of pollutant degradation in liquid layer (sec'1),
      A      =     area of surface impoundment (m2),
      di    '-     depth of liquid layer (m),
      KmU   =     rate of pollutant volatilization from liquid layer (m/sec),
      Qsep    =     rate of seepage beneath the impoundment (m/sec), and
      DV    =     rate of change in the volume of the liquid layer (m3 liquid  layer/sec).
                                       4-117

-------
        Because the total depth of the impoundment (including both liquid and solids layers)
 is assumed constant, the depth of  the  liquid layer  is reduced  as  more  sewage sludge
 accumulates in the solids layer. If the rate at which the solids accumulates is constant over
 the active lifetime of the surface impoundment, the rate of accumulation can be determined
 by dividing the total  depth of the impoundment by its expected active lifetime:      '.
                                      DV =                                  (4-110)
                                             TF

 where:    '                                             .
        dsi     =     total depth of surface impoundment (m), and
        TF     =     estimated active lifetime of surface impoundment (sec).
 The active lifetime of the surface impoundment is calculated as:


                                                                             (4-111)
 where:                                                         .                   -
       Sj     =     concentration of solids in liquid layer (kg/m3), and
       5,     =     concentration of solids in solids layer (kg/m3).

       For the first term on the right of Eq. 4-109, the volume of outflow from the surface
 impoundment (Q0) is calculated to be consistent with assumptions about rates of inflow,
 seepage, and accumulation of the solids layer:


                                    S*\               (   5, \
                                     1  I   f\   A    T*Tlt 1    2 I                (4-H2)
                                    P-l                   P*
The concentration of solids in the  liquid and solids layers  is calculated from  parameters
describing the fraction of solids (by mass) in each layer:
                                                                             (4-113)
              •    P.f,io-(i-p1)pj,              P.P.ioa-jyp,

where:
       PI     =     fraction of solids (by mass) in liquid layer (kg solids/kg liquid layer),
       P2     =     fraction of solids (by mass) in solids layer (kg solids/kg solids layer),
       Pw     =     density of water (kg water/L water),
       Pst     =     particle density of sewage sludge (kg sewage sludge/m3 sewage sludge),
                        '
                                       4-118

-------
         103    =     constant to convert (L) to (m3).
         In both the liquid and solids layers, a pollutant is partitioned between adsorbed and
  dissolved phases.  The partitioning depends on both the pollutant-specific partition coefficient
  and the concentration of solids in the layer:



                                 fdl "
                                                    '5,
  where:                          '
      •fdj     =     fraction  of  total  pollutant  hi  liquid  layer  that  is  dissolved
                      (dimensionless),   .
        Kd     =     soil-water partition coefficient (L water/kg soil), and
        10'3   =     constant to convert (L) to (m3).

        The second term on the right side of Eq. 4-109 describes degradation of the pollutant
 through photolysis, hydrolysis, microbial decay, and other processes.  Values for Kd , are
 taken from studies of hydrolysis and microbial degradation, and are applied to pollutant in
 both dissolved and adsorbed phases.

        The third term. oh the right side of  Eq.  4-109 describes  pollutant loss  through
 volatilization, and is the only term directly linked with human exposure.  The overall mass
 transfer coefficient for volatilization (Kwa) is  calculated  with a  two-film  resistance model
 (Tnomann and Mueller, 1987) in which the overall resistance equals the sum of the liquid and
 gas phase resistances:
                                  1       1     RT • 10'3
                           -     j— =  -? +  —-77jr~                •       (
                                ^voii    Ki      "Kg

 where:
       Kwtl   =     rate of pollutant volatilization from liquid layer (m/sec),
       KI .    = •    mass transfer coefficient for the liquid layer (m/sec),
       Kg     =     mass transfer coefficient for the gas layer (m/sec),
       R  .   =     gas constant (L-atm/mol-K),
   ..   T     =     average air temperature (Kelvin),
       H     = -    Henry's Law constant for pollutant (atm-m3/mol), and
       10"     =     constant to convert (L) to (m3).


       Numerous methods for calculating  Kt and Kg for water surfaces have been proposed
(see for example: Hwang,  1985; Mackay and Leinonen,  1975;  Mackay  and Yeun  1983-
Shen, 1982; Springer etal., 1984; U.S. EPA, 1987b; U.S. EPA, 1989e). This methodology
follows an approach described in U.S. EPA (1987b, 1989e) for estimating volatilization from


                                        4-119

-------
  surface impoundments.  The selection of appropriate equations for, calculating mass transfer
  coefficients depends on two characteristics of the site: (1), the ratio of the impoundment's
  effective diameter (or "fetch") to its depth and (2) the local average wind speed.  Effective
  diameter (hi meters) is defined  as the diameter of  a circle with area equal to that of the
  impoundment.  Depth is defined as that of the liquid layer, which for the purpose of this
  calcuiation is assumed to average half of the impoundment's total depth.  The ratio of fetch
  to depth is therefore calculated as:
                                      de =
                                           &    k                          (4-H6)
                                     FR = —
 where:
        2      =     factor to convert radius to diameter,
        A      —     area of surface -impoundment (m2),
        de     =     effective diameter (or fetch) of surface impoundment (m),
        FR     =     ratio of fetch to depth (dimensionless), and
        d,      —     depth of liquid layer (m).

 For surface impoundments where the average wind speed 1Q m above the liquid surface is
 greater than 3.25 m/s and FR ^  51.2 (as in the scenario used for the surface impoundment
 prototype):
K, = 2.61 IxlO'7.u{
                                                       2/3
                                                                             (4-117)  '
 where:
       2.6llxlO~7    =     empirical constant,  /
       u,0           =   '  average wind speed 10 m above surface (m/sec),
       •Dot-           =     diffusivity of pollutant in water (cm2/sec), and
       Dai,           =     diffusivity of diethyl ether hi water (8.5 x 10'6 cnr/sec).

       Calculation of the mass transfer coefficient for the gas phase is  based  on Hwang
 (1982).  For all  values of FD and uw, the mass transfer coefficient for the. gas layer is
 calculated from:
                          Kg = 1.8xlO-Vo78 Sc™ de™                  (4-118)

where:                                        •
       Kg           =     mass transfer coefficient for the gas layer (m/sec),
       LSxlO'3      =     empirical constant, and
       &G          —     the Schmidt number on the gas side (dimensionless), defined
                           below.
                                       4-120

-------
                                       Scc  = —j-        ,       •             (4-119)


  where:
         fia     =      viscosity of air (g/cm-sec),
         Pa     =      density of ah- (g air/cm3 air), and
         Dca    =      molecular  diffusivity of pollutant in air (cm2/sec).

  Equations 4-117 and 4-118 are sufficient to estimate Kwll, the overall mass transfer coefficient
  for the dissolved fraction of the  pollutant.

         The fourth term on the right side of Eq. 4-109 describes losses of dissolved pollutant
  from the liquid layer as a  result  of the seepage through the solids layer and the floor of the
  impoundment.  The rate of seepage (Qsep) is based on measured values  from sewage sludse
  lagoons.  Only dissolved pollutant concentrations are included in this term; adsorbed pollutant
  concentrations are included in the fifth term of the equation, which describes loss of pollutant
  from the liquid layer as a result of the  diminishing volume of that layer.

        All terms on the right side  of Eq. 4-109 are proportional to the  concentration of
 pollutant in the liquid layer.   A coefficient for the total rate at  which pollutant mass is lost
 from the liquid layer (Ktotl, in m3/sec) can be defined as:                                -


                  Kua= QJdi  +  K^gidiA +  KvoiifdiA + QSfpfdlA + DV        (4-120)

 so that:

                                     Q;C;  = K, ,C,                            (4-Pii
                                     ^'  I     tOll  1                            VT J.4-J./
 Because all estimated rates of pollutant loss are proportional to the concentration of pollutant
 m toe liquid layer, total losses can be partitioned among competing loss processes according
 to fixed ratios.  Of the total mass of pollutant lost from the liquid layer, the fraction lost to
 each process is:
                                   /.
                                             Jf         •'VOll      jp

                                                                               (4-122)
where:
                     fraction of total pollutant lost from liquid layer that is lost in outflow
                     from the impoundment (dimensionless),
                                        4-121

-------
         fdegi    —     fraction of  total pollutant lost  from liquid  layer that  is  lost to
                       degradation (dimensionless),
         /«>/;     =     fraction of  total pollutant lost  from liquid  layer that  is  lost to
                       volatilization (dimensionless),
         fscpi     =     fraction of total pollutant lost from liquid layer that is lost to seepage
                       (dimensionless),  and
         fdeii     =     fraction of total pollutant lost from the liquid layer as a result of the
                       diminishing volume of the liquid layer (dimensionless).

         Solids Layer. Pollutant mass accumulates in the solids layer as the depth of mis layer
  increases and eventually  reaches the surface of the impoundment.   If the only  source of
  pollutant mass  for the solids layer is  the loss estimated for the liquid layer, then:
                                    t  = Kdeg2d2AC2 + Q^faAC2 + DVC2       (4-123)

  where:                      -
        faz     =      fraction  of  total  pollutant  in   solids   layer  that  is   dissolved
                       (dimensionless),
        d2      =      depth of solids layer (m),
        Kdeg2    =      anaerobic rate of pollutant degradation in solids layer (sec^1), and
        C,     =   .  total concentration of pollutant hi  solids layer (kg pollutant/m3 solids
                       layer).

        Similar to the  liquid  layer, the partitioning of a pollutant in the solids layer can be
 expressed as:
                            '     <° '  i * r, .w*  • s,                        (4-124>

 where:                                                              .   .
        Kd     =      soil-water partition coefficient (L water/kg soil),
        S2      =      concentration of solids in solids layer (kg/m3), and
        1CT3    =      constant to convert (L) to (m3).


 A coefficient for the total loss or storage of pollutant in the solids layer (Ktol2, in m3/sec) can
 be defined as:
                                                        + DV                   (4-125)



As with the liquid layer, this coefficient can be partitioned into its individual components:
                                         4-122

-------
                                                                 _  DV
                                                            ./&£>    -jp—         (4-126)
                              wr2                  »r2              ^Wj2

 where:
        /^2    =     fraction of pollutant reaching the solids layer that is lost to degradation
                      (dimensionless),
       fsep2    =     fraction of pollutant reaching the  solids layer that is  lost to seepage
                      (dimensionless), and
       fata    -     fraction of pollutant reaching the solids layer that is stored in the
                      accumulating depth of this layer (dimensionless).

        If concentrations of pollutant in the liquid and  solids layers can be approximated as
 steady-state for the duration of the impoundment's active lifetime, and if the partitioning of
 pollutant among competing loss processes halfway: through the impoundment's active lifetime
 is assumed typical of its  entire active  phase, then the fraction  of each year's  loading  of
 pollutant lost during each  year of the surface, impoundment's active phase can be calculated
 as:
                    fact = /«,/;  + f*gi + /«| + (4p/ •*/*!/) (krf +4,2)           (4-127)

where:                                       .
     •  faa     =     fraction of each year's loading of pollutant lost during each year of the
                     surface impoundment's active phase (dimensionless).


       Finally, if all pollutant is eventually lost from the impoundment and the partitioning
of pollutant mass halfway through the surface impoundment's lifetime is generalized for the
entire mass of pollutant, the fraction of pollutant mass lost through each pathway  can be
calculated as:
                                        4-123

-------
                               f   = **epl +^del1'
                              J SfD
                               'scp          /.
                                           Jo
                                            act
Jvol
fdeg
f
fact
_ Joutl
«p, */«)/«
fact
                                                                               (4-128)
                               out
                                     Jact

  where:                         •
        fsep ,   =     fraction of total pollutant lost from the impoundment through seepage
                      (dimensionless),
        fwl    =     fraction of  total  pollutant  lost from  the  impoundment through
                      volatilization (dimensionless),            •
        fdtg    =     fraction of  total  pollutant  lost from  the  impoundment through
                      degradation (dimensionless), and
        /„„  *  -     fraction of total pollutant lost from the impoundment through outflow
                      (dimensionless).


        These results are used to calculate concentrations of pollutant in groundwater and air
 near the surface  impoundment.

 Method for Groundwater Pathway

        The methods for estimating concentrations of pollutants in groundwater near a surface
 impoundment  are  almost identical to those  discussed above for monofills.   First  the
 concentration of pollutant in sewage sludge is used to estimate the expected flux of pollutant
 info the top of the unsaturated zone.  To simplify the calculations, this  pollutant flux is
 represented as a pulse  of constant magnitude  or "square wave, "  with its duration calculated
 so that the entire  mass  of pollutant will be depleted at the equilibrium rates calculated for the
 active impoundment:
                                TP _        TF

                                    = f^ •  31,536,000        ,                (4"129)
                    ,                                                              •*

where:
                     -     duration of "square wave" for approximating the  loading of
                           pollutant into the unsaturated soil zone (yr),
       TF            =     estimated active lifetime of surface impoundment (sec), and
       31,536,000    =     constant to convert (sec) to (yr).
                                        4-124

-------
   This result is combined with another result from the mass balance calculations to derive a
   conservative estimate of the average flux of pollutant to the unsaturated zone beneath the site:
  where:
         PAiK.j        =     annual average flux of pollutant j leaching through the floor of
                            the surface impoundment (kg pollutant/ha-yr),
         °-01     .     =     constant to convert (mg/m2) to (kg/ha), and
         ci            =     concentration of pollutant/ in sewage sludge (mg pollutant/kg
                            sewage sludge).


         Next the average flux is used to estimate the average concentration of pollutant in
  seepage:                                        '
                                       Qsep  ' 31,536,000

 where:                                                                    .
        0.1    =     constant to convert (kg/ha-m) to (mg/L), and
        CsepJ   =     average concentration of pollutant j in water seeping through .the
                     bottom of the ^impoundment (mg pollutant/L water).

        As discussed in Section 4.3.2 for the monofill prototype, two mathematical models are
 combined for this purpose.  The VADOFT component of the RUSTIC model (U S  EPA
 1989d,g) estimates flow and transport through the unsaturated zone, and the AT123D model
 (Yeh, 1981) estimates pollutant transport through the saturated zone.

       Minor adjustments have been made to the linked models to represent a phenomenon
 unique to the surface impoundment prototype: seepage from a surface impoundment can cause
 local elevation of the  water table if rates of seepage from the  impoundment exceed natural
 rates of aquifer recharge  in the surrounding area.  Such elevation of the water table or
 mounding, has two implications for the expected concentrations of sewage sludge pollutants
 at a receptor well. The first is that the reduced vertical distance between the impoundment
 and the local water table will result  in decreased time of travel for water moving between the
 impoundment and the saturated zone.  The second is that an increased hydraulic gradient will
 form in the aquifer between the surface impoundment and the downgradient receptor well
 This change in the gradient will increase the expected rate of horizontal transport of the
 pollutant through the saturated zone.
PTT*T J° ac?°,mmod^these ^o effects in the model calculations, an approach used in the
RUSTIC model is modified.  The first component (VADOFT) of the modified linked model
performs calculations for a vertical column containing both unsaturated and saturated zones,
                                       4-125

-------
  and predicts the extent to which the elevation of the water table will be increased by the flux
  of water from the impoundment.  Once the vertical column problem has been solved for mass
  and water fluxes at the water table elevation,  the  second model component (AT123D)
  simulates  the movement of  pollutants  through  the  saturated zone, with adjustments to
  represent  increased elevation of the water  table.   Unlike RUSTIC,  however, the present
  methodology does not allow for partial feedback between the unsaturated and saturated zone
  components of the  model; the saturated zone is represented separately  by an analytical
  transport model.
                   A

         Saturated Zone. The  AT123D model accepts as input the flux of pure pollutant mass
  entering the top of the saturated zone,  and does not  consider the extent of the pollutant's
  dilution by water from the source area, or the impact of that water  on groundwater flow
  within the  saturated zone. When the vertical movement of pollutant  through the unsaturated
  zone is  due only  to infiltration throughout the area, the gradient  within the aquifer is a
  function of the water entering the saturated zone, and neglect of the diluted state of the source
  term may be valid. For the.case of a surface impoundment, however, neglect of the extent
  of the pollutant's  original dilution could result hi non-trivial overestimation of the source
  concentration, leading  to an overestimation of pollutant concentrations at the receptor well.
  Furthermore,  neglect of mounding effects could lead to incorrect  assumptions about the
  velocity of groundwater flow near the site.

        These concerns are addressed with three simple adjustments  to the  execution of the
 AT123D model.  First,  to correct for AT123D's potential  overestimation of the  original
 concentration of pollutant at the aquifer's boundary, the mass flux estimated from VADOFT
 results is adjusted by a dilution factor (Df) as follows:
                                    Df= AQ \p      .  •                   (4-132)

 where:
       . Fa     =     the volume of fluid passing through a vertical cross-section of the
                     aquifer oriented perpendicular to the direction of flow, and having a
                     width equal to the source width and a depth equal to the saturated
                     thickness of the aquifer (m3/sec).

       The excess water released by seepage from a surface impoundment also can result in
 a  superimposed  radial velocity field on  the  background or regional  velocity field  of
 groundwater flow.  In other words, the horizontal velocity of water within the aquifer can be
 decreased upgradient of the surface impoundment, and increased downgradient of the surface
 impoundment.  This change hi the velocity field might result in reduced time of travel for
pollutants moving to receptor wells downgradient of the impoundment, which could in turn
lead to reductions hi pollutant degradation prior  to human exposure.  Accurate accounting of
the influence of mixing and degradation would require a fully three-dimensional  flow and
transport model; this methodology uses a simpler approach to estimate a conservative limit
to  pollutant decay within the system.  The limit is estimated by increasing  the estimated
velocity of groundwater flow to account for the maximum downgradient increase in velocity

                                       4-126

-------
   due to the  source.  The velocity increase can be approximated by idealizing the surface
   impoundment as a circular source, so that the rite at which seepage passes outward through
   a cylinder beneath the perimeter of the impoundment is:
                                                                               (4-133)
                                             ••"a

  where:

         v,.      =  -   superimposed radial velocity from water seeping from impoundment
                      (m/sec), and                  .             .
         da     .=     depth of aquifer (m).

         In  addition to increasing the  expected velocity of pollutant transport through the
  aquifer, this  superimposed velocity also would  have the effect of increasing AT123D's
  estimate of pollutant dilution within  the aquifer.   This additional dilution effect  must be
  subtracted back out of the model calculations, because the true dilution is explicitly included
  in the factor introduced by Eq. 4-132.  The model performs this calculation automatically
  based on the following equation for the  anti-dilution factor-
                                                                              (4-134)
                                              vh
 where:                                                                       ,
        Daf    =     anti-dilution factor (dimensionless),
        v,.      =     vertical velocity due to the source (m/sec), and
        v*      =     regional velocity of horizontal groundwater flow (m/sec).
 the v^inrm, h.   »K *          JJ  ' methodology is conservative, because it overestimates
 the velocity beneath the source and does not allow for decreases in the superimposed velocity
 beyond  the source.  As a result, the methodology is more  conservative than a  three-
 dimensional model. In comparison with a two-dimensional cross-sectional flow and transport
 model, the model is more conservative beneath the source, but less conservative beyond the
 oUUlwC.                                               -  ^
          combining the VADOFT model with AT123D, and by adjusting calculations in
mn,   t  ,   9sfaaa^to ^  dil*ion and  superimposed velocity-described above,
concentrations of a pollutant in groundwater at a receptor well can be predicted as a function
of the liquid concentration of pollutant near the floor of the impoundment, the rate of seepage
from the surface impoundment, and hydrogeological characteristics of the area.  It should be
npted  tfiat.all  of the  calculations  described above  are linear  with  respect  to pollutant
concentrations in liquid seeping from the impoundment
                                       4-127

-------
  Method for Volatilization Pathway

         Estimates of exposure  for  the vapor pathway  are based on the  highest  average
  concentrations ,of pollutant to  be encountered over an expected human lifetime.  At the
  maximum rate at which pollutant is lost during the surface impoundment's active operation,
  the fraction that would be lost to all processes over a period equivalent to the life expectancy
  is:
                                     fvls = fact ' fvoll           •                 (4-135)

  where:                                          -
        fiis            -     fraction of pollutant mass that volatilizes over a human lifetime
                             (dimensionless),
        faa            =     fraction of each year's loading of pollutant lost during each year
                             of the surface impoundment's active phase (dimensionless), and
        fwu           =     fraction of total pollutant lost from liquid layer that is lost to
                             volatilization (dimensionless).
        This fraction can be converted to an average flux of pollutant volatilizing from the site
 as:                                                              ..'••-

 where:
       FAwij  =     annual  average flux  of pollutant /( volatilizing  from  the  surface
                     impoundment (kg/ha-yr),                                  •
       Cj      -     concentration of pollutant/ in sewage sludge (mg pollutant/kg sewage
                     sludge),
       /*      =     fraction of pollutant mass  that  volatilizes  over a  human lifetime
                     (dimensionless),
       0.01    =3     constant to convert (mg/m2) to (kg/ha),
       $>      =     concentration of solids in solids layer (kg/m3),
       dfi      =     total depth of impoundment  (m), and
       LS      =     average human lifetime (yr).         . ,     > •

     .  The next step is to relate  releases of volatilized pollutant from the site to the expected
concentration in ambient air.  As .before,  the simplified version of ISCLT described above
to calculate a source-receptor ratio (SRR) is used.   Multiplying the  SRR by the average
volatilized flux and adjusting units yields a conservative  estimate of the expected average
concentration of pollutant hi ambient ah- near the site-

                                                  '
                                        4-128

-------
                                   C    = —*fe/	_                         (4-137)
                                    mj      315.36

  where:           ' -            .               '
         c<*.j         =     average concentration  of pollutant j in  ambient air at the
                             downwind edge of the site (jig pollutant/m3 air),
         SRR          =     source-receptor ratio (sec/m), and
         315.36       =     constant to convert (kg/ha-yr) to (jig/nr-sec).


  4.3.4  Estimating Human Exposure

        To estimate human exposure, the methods discussed in Sections 4.3.2 and 4.3 3 are
  used to estimate the concentrations of each pollutant in air and groundwater near each type
  of surface disposal site prototype.  Estimated concentrations in environmental media are
  converted to  estimates of human exposure based on assumptions about the rate at which the
  average  individual  inhales air  and ingests drinking water.  For air,  human exposure  is
  calculated as:                                                               •

                                        icr3  •  c . . • IA
                               EXP. = 	^                           (4-138)
                                   '          BW          ,               '.         ~

 where:
       EXPj   =     exposure to pollutant/ in sewage sludge (mg pollutant/kg body weight-
                .     day),
       10'3    =     constant to convert units from (fig) to (mg),
       CairJ   =     average concentration of pollutant j  in ambient air at  the downwind
                     edge of the site (jtg pollutant/m3 air),
       I A      =     inhalation  rate (m3 air/day), and
       BW    =     body weight (kg).


Potential exposure to pollutants through ingestion of groundwater is calculated as:


                                          C      TW
                                  EXP. = .  welj                              (4-139)
                                             BW

where:
      C  ij   =     concentration-of pollutant j in well water (mg pollutant/L water), and
      ™    =     volume of water ingested daily (L water/day).
                                       4-129

-------
4.3.5  Data Inputs

       Exhibits  4-21 and 4-22  present the non-pollutant-specific data for the  monofill
prototype and the surface impoundment prototype.
                                  EXHIBIT 4-21
             Site and Sewage Sludge Parameters for Monofill Prototype'
j Parameter
| Area of Monofill (m2)
I Depth of Monofill (m)
|] Distance to Well (m)
1 Thickness of Daily Cover (m)
J Thickness of Permanent Cover (m)
II Time Each Unit Uncovered (hr)
[J Tune Average Unit Contains Sewage"
Sludge (hr) - -
II Sewage Sludge as Fraction of Total
Volume (m3/m3)
| Active Monofill Life (yr)
I! Average Wind Speed (m/sec)
| Average Air Temperature (Kelvin)
I! Vertical Term for Pollutant Dispersion in
Air (dimensionless)
[I Net Recharge (m/yr)
IJ Solids Content of Sewage Sludge (kg/kg)
Value
10,000
3.46
150
0.3
1
12
87,660
0.63
20
4.5
288
1'
0.5
0.20
Reference
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c.
U.S. EPA, 1992c
U.S. EPA, 1992c
U.S. EPA, 1992c
                                    4-130

-------
                                     EXHIBIT 4-22
         Site and Sewage Sludge Parameters for Surface
    Parameter
    Area of Surface Impoundment (m2)
 Value
      —
 20,236
            Impoundment Prototype
 Reference
 =====
 U.S. EPA, 1992c
   Total Depth of Surface Impoundment (m)
              U.S. EPA, 1992c
   Distance to Well (m)
 150
 U.S. EPA, 1992c
   Rate of Inflow (m3/sec)
 0.0022
 U.S. EPA, 1992c
  I Average Wind Speed (m/sec)
 4.5
 U.S. EPA, 1992c
   Average Air Temperature (Kelvin)
 288
 U.S. EPA, 1992c
   Solids Content of Inflow (kg/kg)
 0.03
 U.S. EPA,  1992c
   Solids Content of Liquid Layer (kg/kg)
0.03
 U.S. EPA,  1992c
                                           0.175
              U.S. EPA, 1992c
                                           1200
              U.S. EPA, 1992e
  I Net Seepage Beneath Impoundment (m/yr)
2.5
 U.S. EPA, 1992c
   Depth of Solids Layer (m)
              Assumed half-filled
  I Depth of Liquid Layer (m)
  Vertical Term for Pollutant Dispersion in
  Air (dimensionless)
             Assumed half-filled
             U.S. EPA, 1992c
 | Density of Air at 15 °C (g/cm3)
1.226xlO-3
Weast, 1990
  Viscosity of Air at 15 °C (g/cm-sec)
1.79x10^
 nterpolated from Henry and
Heinke, 1989
       There are several pollutant-specific fate and transport parameters required to maintain
 the mass balance of a pollutant among the three loss processes and to estimate the  rates at
 which those three loss processes occur. In Exhibit 4-23the fate and transport parameters for
 both the monofill and surface impoundment prototypes are presented. For degradation rates
 estimates of both aerobic and anaerobic degradation rates are presented.  As in Round One'
 for the degradation rate  of-a given pollutant in  the unsaturated zone, ten percent of the
 aerobic biodegradation rate is used if an hydrolysis rate was unavailable. For the degradation
 rate for a given pollutant in the saturated zone, the arithmetic-average of the unsaturated zone
 degradation rate  and the anaerobic degradation rate for that pollutant is used.

       To obtain estimates of inorganic Kd values for six Round Two pollutants, studies of
adsorption described in Gerritse et al. (1982) were used.  Gerritse et al. present a range of
^.values for various inorganics in two soil types: sand and sandy loam.  In the sandy soil
there was 0.035 g/g organic matter, 0 g/g clay, 0.22 meq/g cation exchange capacity (CEC)'
and the porewater  had  a  PH of 5. In the sandy loam soil, there  was 0.025 g/g organic
matter, 0.2 g/g clay, 0.16 meq/g CEC, and the porewater had a pH  of 8.  For this analysis
                                      4-131

-------


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-------
               \ .
,  the Kd values from sand, which were lower than those hi sandy loam, were used.  The
  median Kd value from the range available for each of the six Round Two inorganics tested
  was used.

        For aluminum and fluoride, available data on Langmuir isotherm parameters were
  used to estimate Kd values (Bodek et al., 1988).  For aluminum, data were for silica, at a pH
  of 5.  For fluoride, data corresponded to clay loam, containing 10.4 percent clay, 0.94
  percent organic carbon, and 825 /zg/g aluminum, with a pH of 5.9.  For boron, thallium, tin,
  and titanium, Kd values were not available.         •

  4.3.6 Modeling of Surface Impoundments in the Comprehensive Hazard Identification

       For this risk assessment, only surface impoundments were modeled for the surface
  disposal option. Exposure to pollutants in surface impoundments is greater than exposure to
 pollutants in monofills for both the air and groundwater exposure pathways.  Pollutants
 volatilize more readily from surface impoundments than from monofills because there is no
 soil cover.  Pollutants also leach more readily from surface  impoundments because the
 recharge rate to groundwater is higher due to the liquid sewage sludge being placed in the
 impoundment.  Therefore, if a pollutant hi a surface impoundment did not result in high risk
 levels, then its presence hi a monofill also would not be of concern.

4.3.7  Example Exposure Calculations for Surface Disposal

       The following example calculates exposure of humans to methylene chloride present
in sewage sludge placed hi a surface impoundment.  Exposure occurs through ingestion of
groundwater that has received leachate from a surface impoundment and through inhalation
of"methylene chloride that has volatilized from a surface impoundment.

Groundwater Exposure Pathway for Surface Impoundment

       To estimate human exposure through the  ground water pathway, computations must
be made for both the liquid layer of the surface impoundment and the solids layer.

       Calculations  for  Liquid Layer of Surface Impoundment.    Several steps are
necessary to estimate the rate at  which methylene chloride is lost from  the liquid layer of a
surface impoundment. • First, the mass transfer coefficients for the liquid layer of the surface
impoundment and the air layer immediately above it are calculated.  Equation 4-117 is used
to calculate the mass transfer coefficient for the liquid layer:
                                                                                        €>
                                      4-136

-------
                                                                  2/3
                   5T, = 2.611x20-7 • (4.5m/sec)2 • I 9-2*™'6<™W
                                                 8.5x70-6cm2/secj

                     = 5.6xlO-6m/sec


  where:
        2.611xlO'7    =     empirical constant,
        4-5           =     u!0 (average wind speed 10 m above surface) from Exhibit 4-22,
        9.2xlO-6       =     Dw  (difftisivity  of.  methylene  chloride  in  water)  from
                            Exhibit 4-23, and                                        '
        S.SxlQ-6       =     Dah (diffusivity of diethyl ether in water) from text.

        To calculate the mass transfer coefficient for the gas layer immediately above the
 surface  impoundment, the Schmidt  number and  the  effective  diameter of the surface
 impoundment must be calculated. The Schmidt number is calculated using Eq. 4-119:


                                     1.79x10 -tg/cm -sec
                       ScG  = —
                              1.23x20-3g/cm3  • 1.0xlO-\cm2/sec

   .                         =1.5

 where:
        1.79XK)-4     =      ^ (viscosity of air) from Exhibit 4-22,
        1.23xlO'3     =      Pa (density of air) from Exhibit 4-22, and
        1. Oxl O'1       =      Dca (diffusivity of methylene chloride in air) from Exhibit 4-23.


 Equation 4-116 is used to calculate the effective diameter of the surface impoundment:
  ~  20,236m2
= 2. — i -  =
                                                  t „
                                                  160m
where:
       ^            =     factor to convert radius to diameter, and
       20,236       =     A (area of surface impoundment) from Exhibit 4-22.
The mass transfer coefficient for the gas layer is then calculated using Eq. 4-118:
                                       4-137

-------
                         K  = 1.8x70 -3 • 4.5°'78 • 1.5-°'67 •  16Q-0-11
                          o -
                              2.6x70 -3--
                                      sec
  where:
  1.8xlO~3

 4-5
  1-5
  160
                             empirical constant,
                             uIO (average wind speed 10 m above surface) from Exhibit 4-22 ,
                             Scc (Schmidt number on the gas side) calculated above, and
                             ^(efTectivediameterofsurfaceimpoundment)calculatedabove.
  Both Kg and  K, are  then used in Equation 4-115 to calculate the overall  mass transfer
  coefficient for volatilization:
                   -5.6x.70-6ro/sec


                   1.8xl05secfm
                             0.082(L-atm)f(mol-K)  • 288K •  lQ-3m3fL

                               2.QxlO-3(m3-atm)l(mot) • 2.6x10-3m/sec
 where:
5.6X10"6

0.082

288
2.0xlO'3

2.6xlO'3
                            KI (mass transfer coefficient for the liquid layer)  calculated
                            above,
                            R (gas constant) from Exhibit 4-16,
                            T (average air temperature) from Exhibit 4-22,
                            H  (Henry's  Law constant  for  methylene  chloride)  from
                            Exhibit 4-23, and               .
                            Kg (mass transfer coefficient for the gas layer) calculated above.
Taking the inverse of
                                      = 5.4x70 -6m/sec
       Second, the active lifetime of the surface impoundment and the rate of change in the
volume of the liquid layer are calculated. The concentrations of solids in the liquid and solids
layers must first be calculated by using Eq. 4-113:
                                       4-138

-------
            s  =        1200kg/m3  - Ikg/L •  0.03  • 1000L/m3
                       • 0.03  • lOOOL/m3 + (1-0.03) • 1200kg/m


 and:                                          -
                                                                 = 30kg/m
                                  Ikg/L • 0.175 •  1000iy/n3                 3
                       0.03 •  lOOOL/m3 + (1-0.175)  • 1200£g/m3


 where:
        1200  =     p;, (particle density of sewage sludge) 'from Exhibit 4-22,
        1      =     pH. (density of water) from Exhibit 4-16,
        0.03   =     P, (fraction of solids (by mass) .in liquid layer) from Exhibit 4-22,
        0. 175  =     P2 (fraction of solids (by mass) in solids layer) from Exhibit 4-22 and
        1000  =     constant to convert (L) to (m3).


 The active lifetime of the surface impoundment is then calculated using Eq. 4-111:


                              _ 4m •  20.236/B2 • 206kg/m3
                                  0.0022w3/sec  - 3Qkg/m3   •

                              = 2.5x20ssec
where:
      ^          ,   ~     dsi (total depth of surface impoundment) from Exhibit 4-22,
      20,236        =     A (area of surface impoundment) from Exhibit 4-22,
      206           =     ^2 (concentration of solids in solids layer) calculated above,
      0.0022        =     0,  (rate  at  which   sewage  sludge  enters  the  surface
                          impoundment) from Exhibit 4-22, and
      30            =     si (concentration of solids in liquid layer) calculated above.
                                      4-139

-------
  The rate of change in the volume of the liquid layer is calculated using Eq. 4-110:
                                    =  4m • 20,236m2
                                         2.5xlO*sec

                                    = 3.2x20 "
 where:
        4
        20,236
        2.5xl08
=     d^ (total depth of surface impoundment) from Exhibit 4-22,
=.    A (area of surface impoundment) from Exhibit 4-22,  and
=     TF (active lifetime of the surface  impoundment) calculated
      above.
       Third, the volume of outflow from the surface impoundment is calculated using
 Eq. 4-112:                                                                        &
Q0 = 0.0022-
                            sec
                                  1 -
                   30-^
                      m3

                  1200-&
                                                     m
- 2.5—  -20,236m2 -
 	13L	32xlO-4^-
 31,536,000sec     '       sec
                                                      1 -
                                                           206-^
                                                               -3
                                                           1200-
                                                               -3
                   = 2.1x10-*—
                             sec
where:
      0.0022

      30
      1200
      2.5

      3.2X10-4

      206
     Qi  (rate   at  which  sewage  sludge  enters  the  surface
     impoundment) from Exhibit 4-22,
     Sj (concentration of solids in liquid layer) calculated above,
     ft a (particle density of sewage sludge) from Exhibit 4-22,
     Qsep  (rate  of  seepage  beneath  the  impoundment)  from
     Exhibit 4-22,
     £>V(rate of change in the volume of the liquid layer) calculated
     above,  and
     S2 (concentration of solids in solids layer) calculated above.
                                      4-140

-------
        Fourth, Eq. 4-114 is used to calculate the fraction of methylene chloride dissolved in
  the liquid layer:
                       fa =
                                          1
                              1+0.19^- •  10-*—  -30-^-
                                      kg       L      _3
                                     = 0.99
 where:
        0.19   =

        10'3
        30
 Kd (soil-water partition coefficient for methylene chloride) from Exhibit
 4-23,
 constant to convert (L) to (m3), and
 Sj (concentration of solids in liquid layer) calculated above.
        Fifth,  the total rate at which methylene chloride is lost from the liquid layer of a
 surface impoundment can be calculated using Eq. 4-120:
  Ktotl = (2.7x70 -4m3/sec • 0.99) +  (12/yr
                            lyr
                                           31,536,000sec

            (5.4x70-6/n/sec • 0.99  • 20,236m2)  +

                         lyr
                                       2m • 20,236m2)
         (2.5m/yr •


       =  0.13m3/sec
31,536,000sec
                0.99 • 20,236m2) + (3.
where:
       2.7x10^

       0,99

       12

       2
       20.236
       5.4X10-6

      2.5

      3.2x10^
       Q0 (rate at which outflow leaves the impoundment) calculated
       above,
      fa (fraction of total methylene chloride in liquid layer that is
       dissolved) calculated above,
      Kdegl (anaerobic degradatipn rate for methylene chloride)  from
      Exhibit 4-23,
      dj (depth of liquid layer) from Exhibit 4-22,
      A (area of surface impoundment) from Exhibit 4-22,
      K^j (rate of volatilization  of methylene chloride from liquid
      layer) calculated above,
      Qsep  (rate  of  seepage  beneath  the  impoundment)   from
      Exhibit 4-22, and
      DV(rate of change in the volume of the liquid layer) calculated
      above.                                                  -
                                      4-141

-------
         The  last calculations pertaining to the liquid layer estimate  the fractions  of total
  methylene chloride lost from the liquid layer to seepage and as a result of the diminishing
  volume of the liquid layer as the surface impoundment is  filled.  Eq. 4-122 is  used to
  calculate the fraction of total methylene chloride lost from the liquid layer to seepage:
                           .                0.13m3/sec

                           =  L3xlO~2
  where:
        2-5           =     Qsep  (rate  of  seepage  beneath  the  impoundment)   from
                             Exhibit 4-22,
        °-99          =    fa  (fraction of total methylene chloride in liquid layer that is
                             dissolved) calculated above,
        20,236       • =    A (area of surface impoundment) from Exhibit 4-22, and
        °-13          =    K,oa (coefficient for the total rate at which methylene chloride
                            is lost from the liquid  layer) calculated above.

 Eq. 4-122 is also used to calculate the fraction of total methylene chloride lost from the liquid
 layer due to the diminishing volume of the liquid layer:
                           f    =
                           Jdell    ^~     I
                                    0.13m3/sec
 where:                     .
       3.2X1Q-4      =     DV (rate of change in the volume of the liquid layer) calculated
                            above, and
       °-13          =     KMI (coefficient for the total rate at which methylene chloride
                            is lost from the liquid layer) calculated above.


       Calculations for Solids Layer of Surface Impoundment. As for the liquid layer of
the surface impoundment, several computational steps are required for the solids layer. First,
the fraction of total methylene chloride that is dissolved hi the solids layer is calculated using
Eq. 4-124:
                                        4-142

-------
                       fdz =	-	 = 0.96
                             1  + 0.19-  • KT3—  -206-^
                                      kg        L       m*


 where:           .

        0, 19   =     Kd (soil-water panition coefficient for methylene chloride) from Exhibit
                     Q-2.3 ,

        10'3    =     constant to convert (L) to (m3), and
        206    =     5, (concentration of solids in solids layer) calculated above.



        Second, the coefficient for the total loss or storage of methylene chloride in the solids
 layer is calculated using Eq. 4-125,:
                       31.536.



                          31.536.msec
where:

       12           =     K*g2 (anaerobic degradation rate for methylene chloride) from
                           Exhibit 4-23,
       2             ~     d2 (depth of solids layer) from Exhibit 4-22,
       20 236       =     A (area of surface impoundment) from Exhibit 4-22,
                           Q«P  (rate  of  seepage  beneath  the  impoundment)  from
                           Exhibit 4-22,
       °-96                fa (fraction of total  methylene chloride in solids layer that is
                           dissolved) calculated above, and
       3.2X10-4      =      D V (rate of change in the volume of the liquid layer) calculated
                           above.
                                      4-143

-------
         Third, the fraction of methylene chloride reaching the solids layer that  is lost  to
  seepage is calculated using Eq. -4-126:


                              2.5m/yr - —IE-- • 0.96 • 20,236m*
                      Jsep2                         •— -
                           = 8.9x10 ~2
  where:                                          .
        2-5           =     Qup  (rate  of  seepage  beneath  the  impoundment)  from
                             Exhibit 4-22,
        °-96         =  •  /^'(fraction of total methylene chloride in solids layer that is
                             dissolved) calculated above,
        20.236       =    A (area of surface impoundment) from Exhibit 4-22, and
        1.7xlO'2      =    Ktot2 (coefficient  for the total rate at which methylene chloride
                            is lost from or stored in the solids layer) calculated above.


        Fourth, the fraction of each year's loading of methylene chloride lost during each year
 of the surface  impoundment's  active phase must be calculated.  This calculation requires
 seven fractions, as shown in Eq. 4-127.  From Eq. 4-122, the fraction of total methylene
 chloride lost from the liquid layer to volatilization is calculated:


                         ,    _ 5.4x10 "6m/sec • 0.99  • 20,236m2
                     '   Jvoll	
                                          0.13m 3/sec
                             = 0.86


 where:
        5.4x10"6      =      Krn/f  (rate of volatilization of methylene chloride from  liquid
                            layer) calculated above,
        °-99          =     fdi  (fraction of methylene chloride -dissolved in  liquid  layer)
                            calculated above,
       20,236        =     A (area of surface impoundment) from Exhibit 4-22. and
       °-13          =     K-MI (coefficient for the  total rate at which methylene chloride
                           is lost from the liquid layer) calculated above.


Also from  Eq. 4-122, the fraction of total methylene chloride lost from the liquid layer to
degradation is calculated:
                                        4-144

-------
                                       31,S36,OOOsec
                                                  • 2m -20,236m2
                                              0.13—
                             = 0.12


  where:                                              •

         12            =     ^dqti (anaerobic degradation rate for methylene chloride) from
                             Exhibit 4-23,                 .
         2             =     d, (depth of liquid layer) from Exhibit 4-22,
         20.236  . -     =     A (area of surface impoundment) from Exhibit 4-22.

         °'13          =     5"" (coefficient for the total rate at which methylene chloride
                             is lost from the liquid layer) calculated above.

  Also from Eq. 4-122, the fraction of total methylene chloride  lost from the liquid layer to
  outflow is calculated:
                              f    = 2.7x10 ^m^/sec • 0.99
                              Joutl         ~      ~    	
                                          0.13m3/sec
 where:

        2.7X10-4      =     Qa (rate at which outflow leaves the impoundment) calculated
                            above,

        °'99         =     fa (fraction of methylene  chloride dissolved in liquid layer)
                            calculated above, and   ,         -

        °'13         =     K>»» (coefficient for the total rate at which methylene chloride
                            is lost from the liquid layer) calculated above.


 From Eq. 4-126, the fraction of methylene chloride reaching the solids layer that is lost to
 degradation is calculated:
                      f              urannn-.       '20,236m2
                      Jdeg2
                           = 0.89



where:

       12           =      ^W' (anaerobic degradation rate for methylene chloride) from
                           Exhibit 4-23,


                                        4-145

-------
        2             =     J, (depth of solids layer) from Exhibit 4-22,
        20,236        =     A (area of surface impoundment) from Exhibit 4-22. and
        1.7xlO~2       =     Klol2 (coefficient for the total rate at which methylene chloride
                            is lost from or stored in the solids layer) calculated above.

 The fraction of each year's loading of methylene chloride lost during each year of the surface
 impoundment's active phase then can be calculated from Eq. 4-127:


    fact = 0.86 •+ 0.12 + 2.1x10'*  + (1.3x10~2 + 2.5*10~3) • (0.89  + 8.9*70'2) = 1.0
 where:          •                   .                                              -
        0.86         =   •  fml1 (fraction of total methylene chloride lost from liquid layer
                            that is lost to volatilization) calculated above.
        0.12         =     fdefl (fraction of total methylene chloride lost from liquid layer
                            that is lost to degradation) calculated above,
        2.1xlO'J      =     foul, (fraction of total methylene chloride lost from liquid layer
                            that is lost in outflow from the impoundment) calculated above.
        l.SxlO"2      =   "  fsepl (fraction of total methylene chloride lost from liquid layer
                            that is lost to seepage) calculated above,
       2.5x1 0"J      =     fM, (fraction of total  methylene chloride- lost  from the liquid
                            layer as a result of the diminishing volume of the liquid layer)
                            calculated above,
       °-89          =      && (fraction of methylene chloride reaching the solids layer that
                            is lost to degradation) calculated above,  and
       8.9x10'-      =      f^ (fraction of methylene chloride reaching the solids layer that
                            is lost to seepage) calculated above.


       Fifth, the duration of the square wave is calculated by using Eq. 4-129:
                         TP = -                 =
                                1.0 • 31,536,000sec/yr
where:                                         .
       2.5x10s      =     TF  (estimated  active  lifetime  of  surface  impoundment)
                           calculated above,
       i-0           =     faa (fraction of each year's loading of methylene chloride lost
                           during each year of the surface impoundment's active phase)
                           calculated above, and
       31,536,000   =     constant to convert (sec) to (yr).
                                        4-146

-------
          Sixth, the fraction of total pollutant lost from the impoundment through seepage is
   calculated using Eq. 4-128:
                         _ (1.3X10   + ..	,„*„  !   y.7*.±v    _ 1AxJQ-3
   where:

          1.3x10'-      =     fsep] (fraction of total methylene chloride  lost from liquid layer
                             that is lost to seepage) calculated above,
         2.5x10°      =     fMJ (fraction of total methylene chloride lost from the liquid
                             layer  as a result of the diminishing volume of the liquid layer)
                             calculated above,
         8.9x 1O'2      = .    f^ (fraction of methylene chloride reaching the solids layer that
                             is lost to seepage) calculated above, and
         L0           =     fac, (fraction of each year's loading of methylene chloride lost
                             during each.year of the surface impoundment's active phase).

        Seventh, the average flux of methylene chloride to the unsaturated zone beneath the
  surface impoundment is calculated  using Eq. 4-130:



                                0.01-^-  • 1.4*70-3 • 206-^ • 4m • .31.32*
            fA              '  — 	' (mS/m )                 m3             kg
            *  lee, methylene chloride   	'	•	
                                                    S.Oyr


                              = 4.4x10-2  kg
                                        ha-yr


 where:    '                           .         .   '   .       '             '      •     •  •

        °-01          =     constant to convert (mg/m2) to (kg/ha),
        1.4x10°       =     /.c/, (fraction of total methylene chloride lost from impoundment
                            through seepage) calculated above,
        206           =     s: (concentration of solids in solids layer)  calculated above,
•   . ,  .  !j              "     d» (total dePm of surface impoundment) from Exhibit 4-22,
        -31--3          =  ,   Cf (concentration of methylene chloride in sewage sludge) from
                            Exhibit 4-1, and
        ?'°           =     JP (duration of "square wave" for approximating the loading of
                            methylene chloride into the unsaturated soil zone) calculated
                            above.



       Eighth, Eq. 4-131 is used to calculate the average concentration of methylene chloride
in seepage from the surface impoundment:
                                        4-147

-------
              x-.               _     (kg/ha -m)
                sep, methylene chloride
                                                              ha-yr
                                                   2.5-
                                      =  1.7xlQ-3^
                                                  L
 where:
 0.1
 4.4x1 0'2
 2.5
                            constant to convert (kg/ha-m) to (mg/L),
                            FA,CC j (annual  average  flux  of methyiene chloride  leaching
                            through the floor of the surface impoundment) calculated above,
                            and
                            Oxef>  (rate  of  seepage  beneath  the  impoundment)  from
                            Exhibit 4-22.
           .chioncie ls then used jn the linked unsatuTated zone and saturated zone models
 to estimate the concentration of methylene chloride at the well.  C^., for methylene chloride
 is modeled to be lAxW6 mg/L.   This concentration is then used in Eq. 4-139 to estimate
 human exposure:
                        1-4*10
                                             • 2Llday
                                               - ~  =
where:
1.4xlO'6
2
70
                           Cml j (concentration of methylene chloride in well water),
                           IW (volume of water ingested daily) from Exhibit 4-16, and
                           BW (body weight), assumed to be 70 kg.
Volatilization Exposure Pathway for Surface Impoundment

       The volatilization of methylene chloride from a surface impoundment is calculated
below. Many of the parameters required for the volatilization exposure route were calculated
above for the groundwater exposure pathway, and therefore are not repeated below.
                                       4-148

-------
         Equation 4-13 5 is used to calculate the. fraction of total methylene chloride volatilizing
  during a human lifetime:




                                 fvh = 1.0 -0.86 =0.86
  where:       .     '

         L0           =     .4, (fraction of each year's loading of pollutant lost during each

                            year of the surface impoundment's active phase), and

        °-86          =     fvoti (fraction of total pollutant lost from liquid layer that is lost

                            to volatilization) calculated above.




        Equation 4-136 is then  used to calculate the average flux of methylene chloride
 volatilizing from the surface impoundment:
             FA  ,             =  31.3 mg/% • 0.86  • 0.01 • 2Q6kfflm3 • 4m
                vol,methylenechloride            ~ - •     - 2i— -
                                                    70yr


                               = 3.2kgfha-yr                                         -


 where:                                                             '

       31.3   =      Cj (concentration of methylene  chloride  in  sewage sludge) from
                     Exhibit 4-1,            .                   .           ..

       °-86   =      /•/, (fraction of total methylene chloride volatilizing during  human
                     lifetime) calculated above,

       0.01-   =      factor to convert (mg/m2) to (kg/ha),

       206    =  ,    5", (concentration of solids in solids layer) calculated above,  -

       4      =      4,,- (total depth of surface impoundment) from Exhibit 4-22.' and

       70     =      LS (life expectancy), assumed to be 70 yr.




       The source-receptor ratio (SRR)  must be calculated next.   First, the lateral  virtual

distance to the surface impoundment is calculated using Eq. 4-104:
                                        4-149

-------
                 20,236 m
                                                   22.5
 where:
        20.236
        22.5°
                                = 403m
       A (area of surface impoundment) from Exhibit 4-22. and
       0 (the angle subtended by the surface impoundment's width)
       from text.
        The-standard deviation of the vertical distribution of concentration is calculated using
 Eqs. 4-105 through 4-107:
 where:
       20.236
       A (area of surface impoundment) from Exhibit 4-22.
 FromEq. 107:
                           x = lQ-3km/m  • 71m = 0.071 km
where:'
       71
constant to convert (m) to (km), and
r'.(distance from the surface  impoundment's center to the receptor)
calculated above.
From Eq. 106:
                         o.  =  (15.209 • 0.0710-81558) = 1.8m
where:
       15.209
       0.81558
       0.071
      a (corresponding to x = 0.071 km) from Exhibit 4-18,
      b (corresponding to x = 0.071 km) from Exhibit 4-18, and
      x (distance  from  the surface impoundment's center to  the
      receptor) calculated above.
                                      4-150

-------
        Equation 4-103 is then used to estimate the source-receptor ratio:


                    SRR = 2.032 • 	20,236m2 •  1	
                                   (71m + 403m)  • 4.5m/sec • 1.8m
                         = llsec/m

 where:
        2.032     •   =      empirical constant,
        20.236       =      A (area of surface impoundment) from Exhibit 4-22,.
        1             =      v (vertical term for dispersion of methylene chloride in air) from
                            Exhibit 4-22,
        71            =      *' (distance from me  surface impoundment's center  to  the
                            receptor) calculated above,
        403          =      xy  (lateral  virtual  distance  to  the  surface  impoundment)
                            calculated above.
        4-5           =      «/»(average wind speed) from Exhibit 4-22, and
        L8           =      
-------
                EXP            =  10~3mg/\ig  • O.llng/m3 • 20m3/day
                    me thy lene chloride


                                = 3.1x1 0~smg/kg -day
where:                                       .
       10°          =      constant to convert (fig) to (mg).
       0- ! !      "    = .     CairJ (average concentration of methylene chloride in ambient air
                           at the receptor location) calculated above,           .    •
       20            =      IA (hihalation rate) from Exhibit 4-16, and
       70            =      BW (body weight of an adult), assumed to be 70 kg.
                                     4-152

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  4.4    INCINERATION EXPOSURE METHODOLOGIES

         This section evaluates human exposure to inorganic pollutants from the incineration of
  sewage sludge.   For Round Two, the main concern is the emission of inorganic pollutants,
  because organic pollutant emissions were regulated as "Total Hydrocarbons" (THC) in Round
  One. THC was used to take into account the fact that organic pollutants are both destroyed and
•  created in the incineration process.  Although a pollutant-specific limit may be developed for
  dioxins and dibenzofurans in Round Two, in this Section only inorganic pollutant emissions are
  discussed.

        The analysis uses four steps to estimate risks from incineration of sewage sludge:.

        1)      estimate the rate at which pollutants are emitted from incinerator stacks;

        2)      estimate the transport and dispersion of pollutants in ambient air  near
               incinerators, .and determine the extent to which pollutant plumes overlap;

        3)      map expected, ground-level concentrations  of pollutants onto human
               populations; and

       4)      determine the  extent of human exposure to  emitted pollutants and the
               resulting health risks.                                                      -

 4.4.1 Estimating Emissions of Pollutants from Incinerators

       The first  step in estimating human  exposure  to pollutants through incineration is to
 determine  the rate at which pollutants are emitted from the stacks of sewage sludge incinerators.
 The rate at which an inorganic pollutant is emitted is based on the mass of pollutant entering the
 incinerator, the removal efficiency of the furnace, and any operating pollution control devices:
                                                                                (4.140)
                                         ,,000 • 10

where:                                              .
       EJP            =     emission rate for pollutant j at incinerator/? (g pollutant/sec),
       Cj            —     concentration of pollutant j in sewage  sludge  (mg pollutant/kg
                           sewage sludge),
       MP            =     mass of sewage sludge incinerated at incinerator/? each year (kg
                           sewage sludge/yr),
       RJP      •      -     combined removal efficiency for pollutant/' of furnace and control
                           devices for incinerator p expressed as fraction of original pollutant
                           mass  retained  by  the furnace  or pollution  control devices
                           (dimensionless),
       31,536,000   =     constant to convert (yr) to (sec), and
       103           =     constant to convert (mg) to (g).
                                        4-153

-------
         The rate at which a pollutant enters the incinerator is based on the feed rate for sewaee
  sludge (Mp) and the concentration.of pollutant hi the sewage sludge (Cy).  For a given mass of
  an inorganic pollutant entering the incinerator, some fraction will remain in the bottom ash of
  the furnace.  Of the remainder, some is trapped by pollution control devices and the rest is
  emitted from the stack.  To estimate the fraction of pollutant released to the atmosphere, the
  mass entering the incinerator (per unit time) is adjusted for the removal efficiency of the furnace
  and controls (Rjp).  The resulting estimates for emissions from individual incinerators  represent
  stack emissions hi units of grams per second for each pollutant (Ejp).

  4.4.2  Modeling the Dispersion of Pollutants in Ak-

        in Round One, dispersion of pollutants hi air was simulated with the Industrial Source
  Complex Long Term (ISCLT) model (Bowers et.al., 1980;  U.S.  EPA,  1986) as implemented
  in the Graphical Exposure Modeling System for personal computers, or PC-GEMS (U.S. EPA,
  1989a). The model described the dispersion of pollutants as steady-state Gaussian plumes, and
  allowed the user several modeling options.                   '

        In Round One, all incinerator stacks were modeled as point sources. Depending on the
 velocity and  temperature of exit gases,  plume rise was modeled as  either momentum- or
 buoyancy-induced; the appropriate option was  selected automatically by  the program.  Both the
 downwash and plume-rise-by-distance options were used, but (for lack of sufficient data) the
 effects of surrounding terrain were ignored.   For computational efficiency, the dispersion of     ^
 pollutants near each incinerator was modeled only once, using a unit rate of emissions (i e  one    MB
 g/sec of pollutant  emitted per  kg/sec of sewage sludge incinerated).    Resulting dispersion
 estimates were converted to ground-level concentrations at individual  locations, scaled  by
 expected emissions of each pollutant from each individual incinerator.

 4.4.3 Mapping Dispersion and Pollutant Concentrations Onto a Unified,Grid

       In Round One, results from the ISCLT model were reported as dispersion ratios in units
 of /zg/m  of pollutant  concentration  in ambient air per  g/sec of pollutant emissions from
 incinerator stacks.   Separate coefficients were  provided for  selected  locations  in  the area
 surrounding an individual incinerator.  The  model  allowed the  user  to choose between a
 rectangular or polar grid for specifying these locations. In Round One, the rectangular grid was
 selected and coordinates specified in such  a way that results from the modeling of individual
 incinerators could be integrated  into a unified  mapping of dispersion ratios for the U.S. as a
 whole.  Explicit details of this analysis are provided in the Risk Assessment Document (U S
 EPA, 1993a).

      Within each cell of the grid system, expected pollutant concentrations were calculated by
combining emission estimates from each incinerator with results from ISCLT.  When a cell was
                                        4-154

-------
  'impacted by more than one incinerator, pollutant concentrations were summed to calculate total
  expected concentrations for that cell:
 where:
        AA,j    =     estimated ambient air concentration of pollutant y  in grid cell / due to
                     sewage sludge incineration (fig pollutant/m3 air),
        Dip     =     dispersion ratio for grid cell i impacted by incinerator p (fig pollutant/m3
       -             air per g pollutant/sec), and
        n      =     number of incinerators modeled.

        For Round Two,  rather than model the entire U.S. for  this Comprehensive  Hazard
 Identification exercise, modeling results from the analyses performed for Round One were used.
 For each of the 172 sewage sludge incinerators modeled in Round One, the maximum dispersion
 ratio for any cell impacted by the  incinerator was  identified.   The geometric mean of these
 maximum  dispersion ratios was then calculated.  (An arithmetic average was not calculated
 because the maximum dispersion ratios appeared to be log-normally distributed.) The geometric
 mean of the  incinerator's  sewage sludge feed rates, was also determined;  again,  the feed rates
 appeared to be log-normally distributed.  Using an average removal  efficiency  for any given
 pollutant, an "average" ambient air  concentration was estimated:
                                                or
                                   .     I 31,536,000 •  103
where:
                    ~    average ambient air concentration of pollutant j due to sewage
                          sludge incineration 0*g pollutant/m3 air),
                    =    geometric  mean  of  the  maximum dispersion ratios  for  172
                          incinerators (fig pollutant/m3 air per g pollutant/sec),
                    ~    average emission rate for pollutant j (g pollutant/sec),
                    =    concentration  of  pollutant  /  in   sewage   sludge
                          (mg pollutant/kg sewage sludge),
      Mavg          =    geometric mean of sewage sludge feed rates for 172 incinerators
                          (kg sewage sludge/yr),
      Rj            =     combined removal efficiency for pollutant/ of furnace and control
                          devices expressed as fraction of original pollutant mass retained by
                          the furnace or pollution control  devices (dimensionless),
      31,536,000    =     constant to convert (yr) to (sec), and.
      1Q3           =     constant to convert (mg) to (g).
                                        4-155

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  4.4.4  Estimating Human Exposure

         Once average ambient air concentrations of each inorganic pollutant are estimated, an
  estimate of human exposure is made by combining the concentrations with assumptions about
  daily inhalation volume and body weight. Individual exposure to each pollutant is calculated as:


                                           AA.IA 10~3
                                    EXP. = — i -                          (4-1.43)
                                       1       BW

  where:
        EXPj   =   . exposure to pollutant j (mg pollutant/kg body weight-day),
        IA     =    inhalation rate  (m3 air/day),
        10'3    =    constant to c'onvert 0*g) to (mg), and
        BW    =    body weight (kg).

        As can be seen from the equation, the conservative assumption that each person inhales
 air at the estimated (outdoor) concentration for 24 hours per day  for his or her entire lifetime
 is made. It is also assumed that all of the inhaled pollutant is absorbed into the body, and thus
 exposure is effectively equivalent to dose.

 4.4.5  Data Inputs
                                             \
        To estimate human exposure through this pathway, several types of incinerator data are-
 required: sewage sludge feed rates, dispersion ratios, and  removal efficiencies.  As mentioned
 in Section 4.4.3, average values for these parameters were calculated.  For sewage sludre feed
 rates, a geometric mean of the feed rates  for the  172  sewage  sludge incinerators was calculated
 to be 1.04 x 10  kg/yr.  For dispersion  ratios, after the maximum dispersion ratio had been
 identified for each incinerator, the geometric mean was calculated  to be 3,36 ^g/m3 per g/sec.
       The removal efficiencies in two types of incinerators, multiple hearth with wet scrubber
and fluidized bed with wet scrubber,' were needed for inorganic pollutants.   Unfortunately
removal efficiency data were not available for any of the inorganics other than beryllium  which
was already evaluated  in Round One. Therefore, exposures were calculated for two removal
efficiencies:  50- percent and 90. percent.   Fifty percent was chosen  as a  very conservative
number; 90 percent was chosen as a more reasonable number, based on the removal efficiencies
of inorganic pollutants  evaluated in Round One.
                                        4-156

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 4.4.6  Example Calculations for Incineration


        To estimate human exposure to manganese from an incinerator with 50 percent removal
 efficiency,   Eq. 4-142  is used first to estimate the average ambient  air concentration of
 manganese:
         AA       = 3'36 ^S/m3} I (g/sec). •  1620 mg/ks -  1.04xl06 kg/yr • (1-0.5)
           manganese                   ~~ - ' - : — — - 2-=- - - - -
                                    31,536,000 sec/yr • 103 mgfg


                  = 0.090 \igfm3

 where:

       3;36         =     Davg (geometric mean of maximum dispersion ratios) from text,
       1620    •     =     Cj (manganese concentration hi  sewage sludge) from Exhibit 4-1
       1.04x10    =     Mavg (geometric mean of sewage sludge feed rates) from text,
       °-5          -     Rj (combined removal efficiency) assumed to be 50 percent, '
       31,536,000   =     constant to convert (yr) to (sec), and
       JO3         .=     constant to convert (mg) to (g).


       To then calculate the  exposure to manganese, Eq. 4-143 is used:



      EXP        - a09°  VSt™2 ' 20 *"3/
-------
 4.5    RISK CALCULATIONS

        In Sections 4.2, 4.3, and 4.4, estimates were made of exposure to pollutants from sewage
 sludge that is land applied, placed in surface disposal sites, or incinerated.  In this section, the
 exposure estimates are combined with human and ecological toxicity values to obtain estimates
 of risk by pollutant and exposure pathway. If risk values are greater than certain thresholds for
 a given exposure pathway, that pathway is defined  as "critical" for that pollutant.

 4.5.1  Human Health Risk Calculations

        For land application Pathways 1, 2, 4, .5, 12, 13,  14, and 15, and for surface disposal
 and incineration, human exposure estimates to carcinogenic pollutants are combined with cancer
 potency slopes to estimate individual risk:
                                   .  C/y.  = EXPj • q/                            (4-144)

 where:
        CIj     =     incremental  cancer  risk  from  pollutant  j  for exposed  individual
                     (incremental risk of developing cancer per lifetime of exposure),
       EXPj.   =     exposure to pollutant j (mg pollutant/kg body weight-day), and
       q~      =     human cancer potency of pollutant j (mg pollutant/kg body weight-day)'1 ~

       For land application Pathway 3, the exposure  must be modified to account for the
 duration of exposure relative to lifetime:
                                           j •  DE • q}"                          (4-145)

where:
       DE    =    .exposure duration adjustment (number of years  of exposure divided by
                    expected lifetime of 70 years.).

For Pathway 3,  an exposure duration adjustment of (5/70) was used.

       In this analysis, if the  individual risk  for a given pollutant  and exposure  pathway
exceeded a value of 10"4 (one in  10,000), then the pathway was considered critical.

       For non-carcinogenic pollutants for land application Pathways 1 through 5 and 12 through
15, as well as for surface disposal and incineration,  estimated exposure was compared to the
Risk Reference Dose (RfD):
                                         4-158

-------
                 RNCj =
                                                RfD.
                                                                                  (4-146)
  where:
         RJDj   =
ratio of the exposure to the RJD. for pollutant j (dimensionless), and
risk reference dose for pollutant y (mg pollutant/kg body weight-day).
  If the ratio was equal to or greater than one for a given pollutant and exposure pathway  then
  the pathway was considered critical.

         Since May, 1993,  when human  toxicity data were first obtained for the 31 -pollutant
  candidates, some pollutant toxicity numbers have been changed, and others withdrawn  Exhibit
  4-24 presents the q,  and RfD values used in the Comprehensive Hazard Identification for both
  oral and inhalation exposure routes and indicates those numbers which have changed from those
                                      EXHIBIT 4-24
                            Human Health Toxicity Numbers1
            Pollutant
  Acetic acid (2.4-
 j.dichlorophenoxy)

  Aluminum

 I Antimony
 	
  Asbestos3
 Barium
 [Beryllium

I Bis(2-ethylhexyl-)phthalate
[j Boron-

[JBuianone. 2-

 Carbon Disulfide
 Cresol, p-
 Cyanides (soluble salts and
 complexes)
 Dioxins and dibenzofurans
                   _
 Endosulfan-II^
Cancer Potency Slopes
(risk/mg/kg-day)
1 Inhalation
....




8.4






3.0 x 10W4>

Oral
=====
1.9.x- lO'2
" — I.
Reference Doses (mg/kg-day)
Inhalation
J
:


4.3
1,4 x 10'2






1.4x 10^2)


5.7 x lO'3
8.6 x lO'2
2.9xlO"3


3.0 x 106*4' |

•
Oral
===^
l.OxlO'2 j
4.0 xlO-4

7.0 x ID'2
5.0 x lO'3
2.0 x lO'2
9.0 x 10-2
6.0xlO-"2)
— 	 " —
IxlO'1
(3)
2.0 x 1C'2

5.0 xlO'5
                                         4-159

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                                           EXHIBIT 4-24
                           Human Health Toxicity Numbers (cont'd)1
Pollutant
Fluoride
Manganese
Methylene chloride
Nitrate
Nitrite
Pentachloronitrobenzene
Phenol
Polychlorinated biphenyls —
coplanar
Propanone, 2-
Propionic acid, 2-(2,4,5-
trichlorophenoxy)
Silver
Thallium
Tin
Titanium
Toluene
Trichlorophenoxyacetic acid,
0 4 5-
*-,*T,J
Vanadium
Cancer Potency Slopes
• (risk/mg/kg-day)
Tnha'?tini



1.5 x lO'3






-







Oral


7.5 x ID"3


2.6xlO-1

7.7









Reference Doses (mg/kg-dlay)
Inhalation

5 x ID'5®
9.0 x 10-'











4 x 10'1(2)


Oral
6.0 x 10-2
5.0 x 10-3(2>- (5)
6.0 x 1Q-2
1.6
1.0 x 10-'
S.OxlO'3
6.0 x 10"'

l.OxlO'1
8.0 x lO'3 .
5.0 x 10'3
8.0 x 10-5(2)
6.0 x 10-'
(3)
2.0 x 10-'
1.0 x 1012
7.0 x 10'3
Notes:
1 See Section 3.3.4 for a complete description of sources reviewed; see Exhibit 3-7 for references for individual toxicity
numbers unless marked with a (2).
1 Toxiciry data from IRIS (March 3, 1995).
* Toxiciry number withdrawn from IRIS for further consideration (March 3, 1995). No toxicity number available in
HEAST (March. 1994 tables).
4 U.S. EPA (1994c).                            •            '  '
5 This RfD is for water intake, assuming the necessary amount of the trace nutrient has already been ingested with food.
                                               4-160

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        For land application Pathway 11, exposure was compared to an occupational Threshold
 Limit Value-Time  Weighted Average  (TLV-TWA).  The  TLV-TWA  is the time-weighted
 average concentration of a pollutant to which nearly all workers can be repeatedly exposed over
 an 8-hour workday and 40-hour work week, without adverse effect.   The ratio of exposure to
 the TLV-TWA was taken:
        RTC. =  -
           1    TLV-TWA.
                                                                              (4-147)
where:
       RTC,
       TLV-TWAj
ratio  of  the exposure  to  the  TLV-TWA  for pollutant  j
(dimensionless), and
Threshold Limit Value-Time Weighted Average for pollutanty (mg
pollutant/m3 air).
       Exhibit 4-25 presents the Threshold Limit Values used in this analysis. As shown in the
Exhibit, values were not available for three organic compounds.
                                   EXHIBIT 4-25
                        Threshold Limit Values for Pollutants
                                                   Threshold Limit Values-
                                                   Tune Weighted Average
                                                           (mg/m3)1
       Acetic acid (2,4-dichlorophenoxy)
                                                        0.2 fiber/cm3 3
       Bis(2-ethylhexyl) phthalate
       Butanone, 2-
       Carbon disulfide
      Cyanides (soluble salts and complexes)
                                      4-161

-------
Pollutant
Dioxins and Dibenzofurans
1 Endosulfan-H
(I Fluoride
|j Manganese
1 Methylene chloride
1 Nitrate
1 Nitrite
|] Pentachloronitrobenzene
1 Phenol ,
1 Polychlorinated biphenyls (coplanar)
1 Propanone, 2-
Propionic acid, 2-(2'.4,5-trichlorophenoxy)
| Silver
1 Thallium
Tin
Titanium
Toluene
j Trichlorophenoxy acetic acid, 2,4,5-
Vanadium
1
Threshold Limit Values-
Tune Weighted Average
(mg/m3)1

0.1s
1.6
• r-
174
NA
NA
0.5s
19s
0.5s
1780

0.018
• o.i5
2
JO9
188

0.05
Notes:
NA means Not Applicable.
1 American Conference of Governmental Industrial Hygienists (1994).
2 Soluble salts.
* Crocidolite.
J Anhydrous sodium tetraborate.
"Skin.
* Hydrogen cyanide.
7 Fume.         .                                  .        •
* Soluble compounds.
* Titanium dioxide.
                                                 4-162

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 Example Calculations for Human Risk

        For carcinogens, this example estimates the risk associated with the application of sewage
 sludge containing dioxins and dibenzofurans to  agricultural land.   The exposure pathway is
 Pathway 12,  ingestion of fish and water from surface water that receives eroded soil.  In the
 example calculation. for exposure presented in Section 4,2.12, the sum of the exposures to
 dioxins in water and fish was estimated to be 5xlO'n mg/kg-day. To estimate the individual risk
 from this exposure to  these carcinogens, Eq. 4-144 is used:
                                                   .
                                        kg-day          mgjkg-day

                             = 2xlO~4

 where:
       5.2xlO'n    -  =     £XPy (exposure to dioxins) calculated in Section 4.2. 12, and
     .  S.OxlO6       =     q*j (human cancer potency of dioxins) from Exhibit 4-24.


 Given that the individual risk exceeds 10^, this pathway is critical for dioxins and dibenzofurans.

       To demonstrate the use of an exposure duration adjustment for carcinogens, exposure to
 a carcinogen must be calculated for Pathway 3.  Using Eq. 4-5 for beryllium in sewage -sludge
 used on agricultural land:
                                        0.2g  .
                          EXP       -            8
                                                kg-day


where:
       0.2    =     75 (sewage sludge ingestion rate for agricultural land), from Section 4.2.3,
       10'3    =     constant to convert (g) to (kg),
       8      =     ^(concentration of beryllium in sewage sludge) from Exhibit 4-1, and
       16     =     BW (body weight of .child assumed to be exposed  to agricultural land)
                    from Section 4.2.3.
                                        4-163

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  Then using Eq. 4-145:
                              " l.Qr/0     g- •     • 4.3
                                                          /
                                                  70      (mg/kg-day)
  where:

         1.0x10^     "=     EXPy (exposure to beryllium) calculated above,
         5/70          =     £>£ (exposure duration adjustment) from text above, and
         4-3           =     tf* (human cancer potency of beryllium) from Exhibit 4-24.



  Given that the individual risk does not exceed  10^, this pathway is not critical for beryllium.


        For non-carcinogens, boron in sewage sludge applied to forest lands in Pathway 4
  provides  an example.  Total dietary  exposure to boron from wild .animals was calculated in
  Section 4.2.4 to be 0.029 mg/kg-day.  Using Eq. 4-146:
                                         0.029
                                                mg
                                         0.090—^-
                                              kg-day
 where:                             •                    .                 .

       0.029  =     EXPj (exposure to boron) calculated in section 4.2.4, and
       0.090  =     ##} (risk reference dose for boron) from Exhibit 4-24.
 This ratio of exposure to RJD is less than one, and thus this pathway is not critical for boron.



       For Pathway 11, a different type  of risk to human health  is calculated.   Using the
 exposure to manganese calculated in Section 4.2.11  and using Eq. 4-147:
                                                — - 4. 1x20
                                            m3
where:

       4.1xlO'3   •   =    EXPj (exposure to manganese) calculated in section 4.2.11, and
                                        4-164

-------
         1            ==     TLV-TWAj (Threshold Limit Value-Time Weighted Average for
                             manganese) from Exhibit 4-25.

  This ratio of exposure to TLV-TWA is less than one, and thus this pathway is not critical for
  manganese.


  4.5.2 Ecological Risk Calculations

        For Pathways 6,  7, 9, and 10, to estimate risk to an herbivorous or an insectivorous
  mammal, or an earthworm,  an ecological risk quotient was calculated.   The ecological risk
  quotient is the ratio of the predicted exposure to an appropriate lexicological reference value:
 .where:
        RQj    =     ecological risk quotienl for pollutant j (dimensionless),
        EXPAj =     exposure of animal to pollutant j (mg pollutant/kg diet), and
        TRVj   =     toxicological reference value for pollutant/ for an animal'(mg pollutant/ke
                   .  diet).                                                       .  .  -


        Ideally, for toxicological reference values (77?Vs), data for livestock, earthworms and
 small mammals such  as  shrews and moles would be available; however,  toxicity data are
 generally not available for all of .these species.  Instead, toxicity tests are most often performed
 on a select number of "laboratory species,"  such as rats, mice, and dogs.  Results from tests on
 these species are assumed to be represeniative of the sensitivity of species experiencing exposure
 in the field.        •                    ;

       Toxicological reference values for livestock and small mammals were taken from three
 wrro f™011,1?6?;   f JS^R (Agencv for Toxic Substances and Disease Registry) documents;
 WHO (World Health Organization)  documents, and  data  provided  in HSDB (Hazardous
 Substances Data Bank). Each of these sources summarized results of toxicity studies  For this
 analysis, none of the original studies were obtained. The documents reported either NOAELs
 (no  observed adverse  effect levels),  LOAELs (lowest observed adverse effect  levels)  or
 information, necessary lo calculate NOAELs or LOAELs. When only a LOAEL was provided
 the LOAEL was divided by a factor of ten to make it more comparable with the NOAELs  For
 a given pollutant, the lowest NOAEL (or adjusted LOAEL value) reported in any of the sources
 was chosen to be the toxicological reference value for that species. This conservative practice
 was deemed appropriate for this effort.

       As shown in Eq,  4-8 in Section 4.2.6,  animal exposure is calculated  in terms of
concentration of pollutants in the food items (mg/kg);  therefore, the toxicological reference
values also should be in concentration units (mg/kg). While HSDB provides more details on the
protocol of the toxicity studies, the ATSDR and WHO documents only  report the toxicity  test

                                        4-165

-------
 results in terms of mg/kg-day,  regardless  of the exposure metric actually employed in the
 toxicity tests.  When the reference values came  from sources where the exposures were given
 as mg pollutant/kg body weight-day doses, the values were convened to a mg/kg food
 concentration.  In many of the toxicity studies,  exposure was probably originally reported as
 food concentrations. However, because the original studies were not consulted, standard values
 were used for the data needed to  make the conversions from the mg pollutant/kg body weisht-
 day values reported in the ATSDR and WHO  documents and HSDB to food concentration
 equivalents, as described below.

       To make the conversions from mg pollutant/kg body weight-day to food concentration,
 data on body weights,  food consumption rates, and, sometimes, water consumption rates were
 needed.  Body weights for the various species in the tests were taken from the table of reference
 body weights in EPA's report Recommendations for and Documentation of Biological Values for
 Use in Risk Assessment (Table 1-2, U.S. EPA, 1988).  Allometric equations for daily food  and
 water consumption were taken from Table 1-3 of the same source.  Daily doses were convened
 to food concentrations by multiplying the dose by the body weight and dividing by the daily food
 consumption rate.                     .  .

       When the exposure was  given in terms of pollutant concentration in drinking  water, the
 water  concentration was first  convened to a  mg  pollutant/kg  body  weight-day dose  by
 multiplying by the drinking water rate and dividing by the body weight.   The dose was then
 convened to a food concentration in the same manner as described in the previous paragraph
 In essence, the water concentration  was multiplied by the ratio of the water consumption rate
 to the food consumption rate.

       Exhibit 4-26 presents the  TRVs used  for each pollutant  for Pathways 6, 7 and 10   It
also shows which.species was  used to derive the TRY, whether exposure conversions were
necessary, and whether the TRY was based on a NOAEL or a LOAEL. Toxicological reference
values could not  be obtained for endosulfan-II or  2-propanone.
                                    EXHIBIT 4-26
                     Toxicological Reference Values for Mammals
            Pollutant
                  —
 Acetic acid (2.4-dichlorophenoxy)'
    Toxicological
   Reference Value
 (mg pollutant/kg diet)
•	      ^^-«.^_

         180
          Reference
          (Species)
               —
HSDB (mammals)N
 Aluminum1
                                          1400
                      Domingo et al., 1987 (rat)N
 Antimony1
        0.34
Schroeder et al., 1970 (rat)L
 Barium1
                                          0.70
                      Perry et al., 1983, 1985, 1989
                      (rat)N
 Beryllium1
        9.1
                                                        Schroeder and Mitchener,  1975
                                                        (rat)N
                                        4-166

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                                          EXHIBIT 4-26
                     Toxicological Reference Values for Mammals (cont.'d)
                                             Toxicological
                                           Reference Value
                                         (mg pollutant/kg diet)
                                            Reference
                                             (Species)
    Bis(2-ethylhexyl) phthalate
                                  Canning et al., 1991 (rat)N
                                                                Weir and Fisher, 1972 (doe)N
    Butanone. 2-
                                                                Ralston et al., 1985 (rat)N
    Carbon disulfide
                                                                Jones-Price et al., 1984 (rabbirt1-
                                                                Hornshaw et al., 1986 (mink)N
    Cyanides (soluble salts and
    complexes)1
                                 Gerhart, 1987 (rat)N
    Dioxins and Dibenzofurans
                                                                Kociba et al., 1978 (rat)N;
                                                                Murray et al., 1979 (rat)L
                                                               HSDB (mice)*1
                                                               Laskey et al., 1982 (rat)L
   Methylene chloride
                                                               Scrota et al., 1986 (rat)N
   Pentachloronitrobenzene3
                                                               HSDB fdoe)L
                                                               NCI, 1980 (rat)N
   Polychlorihated biphenyls
   (coplanar)1
                                Barsotti and Van Miller, 1984
                                (monkey)1*    .
   Propionic acid, 2-(2,4,5-
   trichlorophenoxy)
                                HSDB (dog)N
                                                               Rungby and Danscher. 1984
                                                               (mouse)L
                                                               Downs et al., 1960 (rat)N
                                                              Schroeder et al.,  1968 (rat)L
                                                              Schroeder et al..  1964 (mouse)N

                                                              NTP, 1990 (rat)N
  Tnchlorophenoxy acetic acid,
  2,4,5-'
                                HSDB (rat)N
                                                              Domingo et al.,  1985 (rat)N
Notes:
1 Secondary source reported exposure
in units of mg pollutant/kg body weight/day.
                                            4-167

-------
   " Secondary source reported exposure in units of mg pollutant/kg drinking water.
   1 Secondary source reported exposure in units of mg pollutant/kg food.
   N Toxicological Reference Value was based on a NOAEL.
   L Toxicological Reference Value was based on a LOAEL.


         For soil-dwelling organisms in Pathway 9, TRVs also were needed.  The soil-dwelling
   biota includes a  taxonomically very diverse array  of  organisms.   There  are  very few
   lexicological,data available, however, for most groups of soil-dwelling organisms. In ecological
   risk assessments, one or a few species of earthworms are generally chosen to represent the soil-
  dwelling niche. Therefore, searches focused on toxicity data for earthworms for the Round Two
  candidate pollutants.                                        .       .

        For Pathway 9, exposure  to pollutants  in soil by  earthworms  is  measured by the
  concentration of the pollutants in the sewage sludge/soil; therefore, the TRVs for earthworms
  should be in units of soil concentration. While there is a considerable amount of toxicity data
  for earthworms, the variability in test quality and designs  makes results difficult to compare-
  thus, it is very difficult to assess potential environmental hazards of pollutants to earthworms
  (Roberts and Dorough,  1985; Edwards and Bohlen, 1992).  There have been recent attempts to
  standardize earthworm toxicity testing protocols (Roberts and Dorough, 1984; Callahan et al
  1994). However, while standard laboratory testing protocols should help in comparing toxicities
  of different pollutants or sensitivities of different species of earthworms, many of thelaboratory
  testing protocols produce results mat are almost impossible to interpret in terms of field exposure
  (Edwards and Bohlen, 1992). For instance, while placing earthworms in contact with pollutants
 on filter papers in Pern dishes for two days may provide measurable LC50s,  it is not clear how
 these  results can be used to determine risk from exposure to pollutants in the field   In short
 there  is a dearth of toxicity data for earthworms that can be used in risk assessments.

        The toxicity literature was searched through computerized databases (e g   BIOSIS and
 HSDB) and recent review articles  were examined to find toxicity information on earthworms or
 other soil biota for the Round Two  candidate pollutants (e.g., Callahan et al 1994-  JEdwards
 and Bohlen, 1992; Beyer, 1990; Roberts and Dorough, 1985). Usable data were found only for
 two of the pollutants.  For phenol, Neuhauser and  Callahan (1990) determined a NOAEC (no
 observed  adverse effect  concentration) of 5900  mg pollutant/kg soil  for mortality  in  the
 earthworm Eisema fetida.  The  earthworms were  exposed for eight weeks.to phenol  in a
 combination of sand and horse manure in Petri dishes.  In a separate study,  Hartenstein et al
 (1981) investigated the effects of cations (including heavy metals) and  anions added to activated
 sewage sludge on the growth  of E. fetida.   The only Round Two metal investigated  was
 manganese.    It  was determined  that manganese at the  highest level  tested  (22 000  mg
 pollutant/kg sludge) was innocuous to this species of earthworms.  Therefore, a conservative
 NOAEC estimate of 22,000 mg  pollutant/kg  sludge is used for manganese.  Exhibit 4-27
summarizes these available data.
                                         4-168  ,

-------
                                      EXHIBIT 4-27
                Toxicological Reference Values for Sou-Dwelling Organisms
         Pollutant
    Manganese
        Toxicological Reference
         Value (NOAEC in mg
      pollutant/kg sewage sludge)
     ~"         • '      I,....
                22,000
      Reference
      (Species)
      =^===
Hartensteinet al., 1981
    (Eisenia fetida)
   Phenol
                                     5,900
                                    Neuhauser and Callahan, 1990
                                           (Eisenia fetida)
  Example Calculation for Ecological Risk   .

  ; ,^o  T° estflate^isk to animals from sewage sludge-amended land, the same equation Eq
  4-148, is used for Pathways 6, 7, 9, and 10.  As an example, the risk for predators of soil
  dwellmg organisms (Pathway 10) through exposure to manganese in sewage sludge-amended
  agricultural soil can be estimated using Eq. 4-148:
                                 manganese
                                            llmg/kg
 where:
        10
        17
EXPAj (exposure to manganese) calculated in Section 4.2.10, and
TRVj (toxicological reference value for manganese) from Exhibit 4-26.
                                                                       10 is «*
4.5.3  Human Health and Ecological Risk Results

       Presented  in  this section are estimates of risk for those pollutant-exposure pathway
combinations for which all pollutant-specific data are available.   For these estimates  95th
percentile pollutant concentrations, with non-detects  set equal to the minimum detection 'level  '
as determined in the 1988 National Sewage Sludge Survey were used.  Risks for each of the land
application exposure pathways are presented first, followed by risks for surface disposal and
mcmeration Note that in the following exhibits, a blank entry means that a risk estimate could
not be calculated for that pollutant-pathway combination, either because not all pollutant-specific
data  were available or, in the case of human endpoint pathways, because neither q* or RfD
values were available.                    -           •                                y
                                        4-169

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-------
                                      EXHIBIT 4-33
                Risk Results for Highly Exposed Individual for Pathway 6
Pollutant
Aluminum
Beryllium
Boron
Dioxins arid
Dibenzofiirans
Fluoride
Manganese
Polychlorinated
biphenyls (coplanar)
Silver
Titanium
Risk Quotient1
Agricultural
Land
100 ,
0.04
0.7
0.03
10
200
5'
\
0.02
7
Forest
80
0.3
4
0.6
30
800
80
0.3
0.7
Reclamation
Site
100
0.03
0.7
0.03
10
200
4
0.01
7
Public
Contact Sites
. 80
0.3
4
0.6
30
800
80
0".3 :
0.7
1 Ratio of exposure to ecological toxicological reference value.
                                          4-174

-------
                    EXHIBIT 4-34
Risk Results for Highly Exposed Individual for Pathway 7

I Pollutant
Acetic acid (2,4-
| dichlorophenoxy) '
1 Aluminum
•jj Antimony
1 Barium
-j| Beryllium
Bis(2-ethylhexyl) phthalate
jj Boron
|j Butanone, 2-
j| Carbon disulfide
I Cresol, p-
Cyanides (soluble salts and
jj complexes)
[Dioxins and Dibenzofurans
	 	 	 	 ; 	
Fluoride
jj Manganese
1 Methylene chloride
Pentachloronitrobenzene
Phenol
Polychlorinated biphenyls
(coplanar)
Propionic acid, 2-(2,4,5-
j trichlorophenoxy)
1 Silver
[ Thallium
Tin
1 	 	 	 _ 	

Agricultural
Land
<0,01.
0.4
1
40.
0.01
. 0.02
0.01 .
<0.01
<0.01
0.01
0.2
0.4
0.6
1
<0.01
<0.01
<0.01
0.6
<0.01
0.2
0.03
2
Risk Quotient1
Forest
'
<0.01
0.4
1
40
0.01
0.02
0.01
<0.01
<0.01
0.01
0.2
0.4
0.6
1 .
<0.01
<0.01
<0.01 .
0.6
<0.01
0.2
0.03
2

Reclamation
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0.6 1
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0.2
0.03
2 I
                      4-175

-------
                                       EXHIBIT 4-34
            Risk Results for Highly Exposed Individual for Pathway 7 (cont'd.)
Pollutant
Titanium
Toluene
Trichlorophenoxy acetic acid,
2,4,5-
Vanadium
Risk Quotient1
Agricultural
Land
0.2
<0.01
<0.01
0.2
Forest
0.2 .
<0.01
<0.01
0.2
Reclamation
Site
0.2
<0.01
<0.01
0.2
 1 Ratio of exposure to ecological toxicological reference value.
                                      EXHIBIT 4-35
                Risk Results for Highly Exposed Individual for Pathway 9
Pollutant
Manganese
Phenol
Risk Quotient l
Agricultural
Land
0.02 .
<0.01
Forest
0.07
<0.01
Reclamation
Site
0.02
<0.01
Public
Contact Sites
0.07
<0.01
1 Ratio of exposure to ecological toxicological reference value.
                                          4-176

-------
                                    EXHIBIT 4-36
              Risk Results for Highly Exposed Individual for Pathway 10
          Pollutant
  Antimony
  Barium
  Dioxins and
  Dibenzofiirans
  Fluoride
  Manganese
  Thallium
                                                 Risk Quotient1
Agricultural
   Land
     10
    0.6
  <0.01
50

80
                                             0.04
Ratio of exposure to ecological toxicological reference value.
         Reclamation
             Site
                                                            10
                                                           0.6
                              <0.01
   Public
Contact Sites
     50

     80


     JL
     2
                                                                          0.04
                                      4-177

-------
                    EXHIBIT 4-37
Risk Results for Highly Exposed Individual for Pathway 11
Pollutant
Aluminum
Antimony
Barium
Beryllium
Bis(2^ethylhexyl) phthalate
Boron
Butanone, 2-
Cresol, p-
Cyanides (soluble salts and complexes)
Endosulfan-H
Fluoride
Manganese
Methylene chloride
Phenol
Polychlorinated biphenyls (coplanar)
Propanone, 2-
Silver
Thallium
Tin
Titanium
Toluene
Vanadium
Exposure
as a Fraction of TLV-TWA
0.1
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
. <0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01

-------
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-------
                         EXHIBIT 4-43
Risk Results for Highly Exposed Individual for Incineration Pathway
Pollutant
Barium
Boron
Manganese
Exposure/RfD for 50%
Removal Efficiency
0.2
<0.01
0.5
Exposure/RfD for 90%
Removal Efficiency
0.04
<0.01
0.1
                           4-184

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        5. FURTHER ANALYSES OF ROUND TWO POLLUTANTS

 5.1   INTRODUCTION

       Chapter 4 presented the risk assessments used in the Comprehensive Hazard Identification
 to evaluate the list of candidate pollutants for the Part 503 Round Two regulation.  In that
 Chapter, results are presented only for those pollutant-exposure pathway combinations for which
 all pollutant-specific data are available.  Examples of pollutant-specific data are plant-uptake
 slopes for different crops; animal  uptake slopes for  livestock, poultry,  etc.;  distribution
 coefficients (K^);  and human and ecological toxicity values.  In this chapter, the candidate
 pollutants that warrant further consideration for the final list are presented. For each pollutant,
 the critical pathways, defined as exposure pathways for which the carcinogenic risk is 1 x 10~*
 or higher,  the ratio of exposure to the Risk Reference Dose  (RfD)  is one or greater, or the
 ecological risk quotient (RQ) is one or greater, are summarized.


 5.2    POLLUTANTS THAT WARRANT FURTHER CONSIDERATION

       Based on the results of the risk assessments of the Comprehensive Hazard Identification,
 12 pollutant candidates have critical pathways for land application and five pollutant candidates
have critical pathways for  surface disposal.   These pollutant candidates and their critical
pathways are summarized below in Exhibits 5-1 and 5-2, respectively.  None of the inorganic
pollutants evaluated had a critical pathway for incineration.
                                       5-1

-------
                                  >         EXHIBIT 5-1
                        Pollutants with Critical Land Application Pathways
I Pollutant
|| Aluminum
Antimony
Barium
J] Beryllium
|| Boron
| Dioxins and
Dibenzofurans
|| Fluoride
Manganese
PCBs-coplanar
Thallium
1 Tin
Titanium
' '..
Critical Agricultural Pathways
6
7, 14
7, 10, 14
14

2, 3, 10, 12, 13, 15
6, 10
3, 6, 7, 14
3, 4, 5, 6, 15
3
7
6
:^ 	
..
Critical Non-Agricultural Pathways
	
6 (for., rec., pub.)
7 (for., rec.); 10 (for., pub.); 14 (for., rec.,
pub.)
7 (for., rec.); 10 (for., rec., pub.); 14 (for., I
rec., pub.) . j
14 (for., rec., pub.) j
6 (for., pub.) j
3 (for., rec., pub.); 10 (for., rec., pub.); 12 1
(for., rec., pub.); 13 (for., rec., pub.);
15 (for., rec., pub.)
6 (for., rec., pub.); 10 (for., rec., pub.)
3 (for., rec., pub.); 4 (for., rec.); 6 (for.,
rec., pub.); 7 (for., rec.); 10 (for., pub.); 14
(for., rec., pub.)
3 (for., rec., pub.); 4 (for., rec.); 5 (for.,
rec.); 6 (for., rec., pub.); 13 (for., rec.);
15 (for., rec., pub.)
	 " 	 	 	 . 	
3 (for., rec., pub.)
7 (for., rec.)
6 (rec.) ||
 Notes:
 Pathway 2 = residential .home gardener
 Pathway 3 = child ingesting sewage sludge
 Pathway 4 = human ingesting animal products
 Pathway 6 = livestock ingesting forage/pasture
 Pathway 7 = livestock ingesting sewage sludge
 Pathway 10 = soil organism predators ingesting soil organisms
 Pathway 12 = humans ingesting surface water and fish
 Pathway 13 = humans inhaling volatilized pollutants
 Pathway 14 = humans ingesting groundwater
 Pathway 15 = breastfeeding infant
.for. = forest land
 rec. = reclamation site
 pub.  = public contact site           .
                                                5-2

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                                     EXHIBIT 5-2
                   Pollutants with Critical Surface Disposal Pathways
Pollutant
Antimony
Barium
Beryllium
Dioxins and
Dibenzofurans
Manganese
Surface Impoundments
Groundwater
Groundwater
Groundwater
Air
Groundwater
       From Exhibits 5-1 and 5-2, it is evident that the organic candidate pollutants dioxins and
dibenzofurans as well as coplanar PCBs have more critical pathways than the inorganic candidate
pollutants, except for manganese, which has the same number of critical pathways. These two
organic pollutant candidates are recommended to be included on the list of pollutants for the
Round Two regulation.  The Agency has decided not to  recommend including any of the
inorganic pollutants on the list for the Round Two regulation, however. The justifications for
that decision are presented in Appendix D on a pollutant by pollutant basis.
                                         5-3

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   6. LIST OF POLLUTANTS FOR THE ROUND TWO REGULATION
                         SUBMITTED TO THE COURT

        In May, 1993, the Agency submitted a list of 31 pollutant candidates for the Part 503
 Round Two regulation to the District Court in Oregon.  A copy of the court notice is presented
 in Appendix Dl. On November 30,  1995, EPA submitted the final list of pollutants for the Part
 503 Round Two regulation to the court.  A copy of that court notice is presented in Appendix
 D2.                   '

        After considering the results of the Comprehensive Hazard Identification, the analysis of
 pollutants that warranted further consideration,  and information received from others,  EPA
 concluded that two pollutants should be on the list for each use or disposal practice.  Tliey are:
 dioxins/dibenzofurans (all monochloro to octachloro congeners) and polychlorinated biphenyls
 (coplanar).  The court notice indicates that EPA may, hi the exercise of its discretion, determine
 to add  or delete other pollutants to or from this list at the tune the Round Two regulation is
 proposed.                                                         .

        In addition to the list of pollutants submitted to the  court, EPA may change  a limit for
 any of the pollutants in the Round One regulation  during development of the  Round  Two
 regulation. For this reason, the Round One pollutants also are considered pollutants for the
 Round Two regulation.

       Including the pollutants from Round One regulation, the list of pollutants for the Part 503
 Round Two regulation by use or disposal practice is:

 Land application
       arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, zinc,
       dioxins/dibenzofurans, and coplanar polychlorinated biphenyls

 Surface disposal          .
       arsenic, chromium, nickel, dioxins/dibenzofurans, and coplanar polychlorinated
       biphenyls

 Sewage sludge incineration
       arsenic, beryllium,  cadmium, chromium,  lead,  mercury,  nickel, dioxins/
       dibenzofurans, and coplanar polychlorinated biphenyls

       Dioxins/dibenzofurans and coplanar polychlorinated biphenyls were included  on the list
 of pollutants for sewage sludge incineration even though they were regulated under the Total
Hydrocarbons operational standard hi Round One. EPA currently is conducting a reassessment
of  dioxins/dibenzofurans.    Because the   results  of  this  assessment are   unknown,
dioxins/dibenzofurans were included on the Round Two list of pollutants for all use or disposal
practices. At the completion of  the  dioxin  reassessment,  EPA may decide not to regulate
                                         6-1

-------
dioxins/dibenzofurans for  a particular use or disposal practice of may. decide to regulate
dioxins/dibenzofurans on an accelerated schedule.
                                          6-2

-------
                               7.  REFERENCES
                                                                                    w
  Abt Associates Inc.  1989.  Characterization of Surface Disposal for Wastewater Sludge.
        Memorandum to Alan Rubin, U.S. EPA Office of Water Regulations and Standards
        March 27.

  Agbenin, J.O., G. Lombin, and JJ. Owunubi.  1991.  Direct and Interactive Effect of Boron
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 Agency for Toxic Substances and Disease Registry. 1989. Toxicological Profile for Phenol.
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 Agency for Toxic Substances and Disease Registry.  1990.  Toxicological Profile for Silver.
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 Agency for Toxic Substances  and  Disease Registry.  1992a.  Toxicological Profile for
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 Agency for Toxic Substances and Disease Registry.   1992b.  Toxicological Profile for
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 Agency for Toxic Substances and Disease Registry.   1992c.   Toxicological Profile  for
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 Agency for Toxic Substances and Disease Registry. 1992d:  Toxicological Profile for Boron
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 Agency for Toxic  Substances and Disease  Registry.   1992e.   Toxicological  Profile for
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Agency for Toxic Substances and Disease Registry. 1992f.  Toxicological Profile for Carbon
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       205-88-0608. U.S. Public Health Service. ATSDR/TP-91/09.                  '
                                      7-1

-------
  Agency for Toxic Substances and Disease Registry.  1992g.   lexicological Profile for
         Cresols.  Prepared by Syracuse Research Corporation under subcontract to Clement
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  Agency for Toxic Substances and Disease Registry.   1992h.  Toxicological  Profile  for
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        International Corporation under contract  no.  205-88-0608.   U S  Public Healrh
        Service.  ATSDR/TP-91/19.                                    '
                                          v

  Agency for Toxic Substances and Disease Registry.   1992L   Toxicological Profile for
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                                   n°"  2°5"88'0608-    U'S'  P""*  Health Service.
 Agency for Toxic Substances and Disease Registry.  1992J.  Toxicological Profile for Tin
        and  Compounds.   Prepared  by Life  Systems under subcontract  to  Clement
 Agency for Toxic Substances. and Disease Registry. 1992k. Draft: Toxicological Profile for
       Toluene.  Prepared by Life Systems under  subcontract to  Clement International
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 Agency for Toxic Substances and Disease Registry.  19921.  Toxicological Profile  for
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Agency for Toxic Substances and Disease Registry: 1993a. Draft: Toxicological Profile for
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Agency for Toxic  Substances and Disease Registry.   1993b.   Toxicological  Profile for


                                        under contract no- 205-88-0608- u-s-
      Bm™             f d MtelSe RegiStty-  1993C'  Toxicological Profile  for
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             10                                  205-88-0608.  U.S. Public Health

       vl'^p^^rc^ DiS6aSe Regis&y-   1993d-  Toxicological Profile for
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      Service. ATSDR/TP-92/09.                                            ncdim
                                      7-2

-------
  Agency  for Toxic Substances and Disease Registry.  1993e.  Toxicological  Profile  for
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  Agency  for Toxic Substances and Disease Registry.  1993f.  Toxicological  Profile  for
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  Agency for Toxic Substances and  Disease Registry.   1993g.  Toxicological  Profile for
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                                       7-3

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                                       7-4

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                                      7-5

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                                     .7-12

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   Singh, A., R. Chhabra, and I.P. Abrol. 1979a. Effect of Fluorine and Phosphorous on the
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                                       7-13

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                                      7-14

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                                     7-15

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   U.S. EPA.  1991a.  Human Health" Risk Assessment for Dioxin in Pulp and Paper Sludge-
         Technical Support Document for the Proposed Land Application Rule.  April.   "

   U.S. EPA. 1991b.  PIRANHA.  Version 2.0. Environmental Research Laboratory, Office
         of Research and Development:

   U.S. EPA. 1992a.  Technical Support Document for Land Application of Sewage Sludge
         Office of  Water,  Office  of Science and  Technology.    EPA 822/R-93-001a
         November.                     .     "         :

  U.S. EPA.  1992b.  Technical Support Document for Sewage Sludge Incineration  Office
         of Water.  EPA 822/R-93-003.  November.                            -_.*««

  U.S. EPA. 1992c. Technical Support Document for the Surface Disposal of Sewage Sludge
        Office of Water.  EPA 822/R-93-002.  November.                    "

  U.S. EPA. 1992d. Estimating Exposure to Dioxin-Like Compounds.  Review Draft  Office
        of Research and Development.  EPA/600/6-88/005B.  August.

  U.S. EPA^  1993a. Human Health Risk Assessment for the Use and Disposal of Sewage
 U.S. EPA.  1993b   Comparison and Rank of Proposed Human Health Bioaccumulation
       Factors for the Great Lakes Initiative. EPA-822-R-93-010. Office of Water. August.
 U'S- EP£™94t  Revision of Assessment of Risks to Terrestrial Wildlife from TCDD and
       Ism oncSt a* PSf S1U??f •  Prepared by Abt Associates **. under contract no. '
       68-CO-0093 for the Office of Pollution Prevention and Toxics. December.

 U.S. EPA.   1994b.   Estimating  Exposure  to  Dioxin-Like Compounds    Volume II-
       Properties, Sources, Occurrence and Background Exposures.  Office of Health and
       Environmental Assessment. June. EPA/600/6-88/005Cb. External Review Draft.
U"S' ^r!^40^1 * Assessment Document for 2,3,7,8 - Tetrachlorodibenzo-p-Dioxin
       (TCDD) and Related Compounds. Volume II. EPA/600/BP-92/001b. External Review
       Draft. June.

U.S. Geological  Survey.   1992.  Element Concentrations  in Soils and  Other Surficial
       Materials of the Conterminous United States.  H.T. Shacklette and  J.G Boerngen
       U.S. Geological Survey Professional Paper 1270. Second printing.

Vanoni  Vita A. (ed.).  1975.  Sedimentation  Engineering.   Prepared by the ASCE Task
      Committee for the Preparation of the Manual on Sedimentation of the Sedimentation
      Committee of the Hydraulics Division, New York, NY.
                                      7-16

-------
  Verschueren, K.  1983.  Handbook of Environmental Data on Organic Chemicals   Van
         Nostrand Reinhold Co., New York, NY. 2nd ed.  [Cited in ATSDR, 1992f, 1993b.]

  Voight, G., K. Henrichs, G. Prohl, and H.G. Paretzke.  1988.  Measurements of Transfer
         Coefficients for 137Cs, 60 Co, 54 Mn, 22 Na, 1311 and 95mTc from Feed into Milk
         and Beef.  Radiation and Environmental Biophysics. 27:153-164.

  Walton, K.C. 1987.  Effects of Treatment with Sodium Fluoride and Subsequent Starvation
        on Fluoride Content of Earthworms.  Bulletin of Environmental Contamination and
        Toxicology.  38:163-170,

  Wang, C.H. and F.E. Broadbent. 1972, Kinetics of Losses of PCNB and DCNA in Three
        California Soils. Soil Sci. Soc. Amer. Proc.  36:742-745.

  Weast, R.C. (ed.).  1990.  CRC Handbook of Chemistry and Physics  70th ed  CRC Press
        Inc., Boca Raton, FL.         -                     ,

 Webber, M.D H.D.  Monteith, and D.G.M. Corneau. 1983. Assessment of Heavy Metals
        and PCBs at Sludge Application  Sites.  Journal  of the Water Poll. Control Fed.


 Weir, R.J., Jr. and R.S.S Fisher.  1972.  Toxicologic Studies on Borax, and  Boric Acid
       Toxicol. Appl.  Pharmacol.  23:351-364. [Cited in ATSDR, 1992d.]

 Whelan, B.R.   1993   Effect of Barium Selenate Fertilizer on the Concentration of Barium
       in Pasture and Sheep Tissues.  J. Agric. Food Chem. 41:768-770.
             '9  w A«-   U, -L  Infant GTOV/th and Human Milk Requirements.
       Lancet.  2:161-163.  [Cited in Smith, 1987.]

WHO.  1982.  World Health Organization.  Environmental Health Criteria 24- Titanium
       Geneva.                                                                  ' .

Wilson  J.T., J.F. McNabb, D.L. Balkwill, and W.C. Ghiorse.  1983.  Enumeration and

                            ria Indigen°US tO a Shallow Water-Table Aquifer.  Ground
Yakushiji  T  LWatanabe  K.Kuwabura,etal. 1978. Long-Term Studies of the Excretion
      of PolychJonnated Biphenyls (PCBs) Through the Mother's Milk of an Occupational

                       ArCh' EnVir°n' C°ntam' T°XiCOL 7:493-504-
      1993]            rC'  nVr°n'   °ntam'  °XiCOL 7:493-504-  tcited in ATSDR,
                 fT         Transport One-,  Two-, and Three-Dimensional
                of  Waste Transport in the Aquifer System.   Oak  Ridge National
      Laboratory, Environmental Sciences Division.  Publication No. 1439.  March.
                                     7-17

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           APPENDIX A

ANALYSIS OF POLLUTANTS DETECTED
LESS THAN TEN PERCENT OF THE TIME

-------

-------
  Introduction

         EPA conducted  two screening analyses to  determine if any of the 69 pollutants
  detected less than ten percent of the time in sewage sludge might still pose an unacceptable
  risk  to human  health.   For the first screening analysis, EPA  used the algorithms  from
  agricultural Pathway 3.  This pathway tends to result in high risk because small children are
  directly ingesting sewage sludge, without any of the mitigating  influences of degradation
  dilution, etc. found in other pathways.  For the second screening analysis, EPA Devaluated
  other pathways  for pollutants with relatively large cancer potency slopes, or q,* values.

        To conduct these analyses, human toxicity data were needed.   Exhibit A-l presents
  the available human toxicity data for the 69 pollutants as well as each pollutant's frequency
  of detection, as  measured in the 1988 National Sewage Sludge Survey (U.S. EPA,  1989a).


  Screening Analysis Based on Pathway 3

        To calculate exposure from agricultural Pathway  3, the only pollutant-specific  data
  required is the pollutant's concentration in sewage sludge, as described in Section 423
  EPA chose to use 98th percentile pollutant concentrations with non-detects set equal to the
 minimuni detection level.  The Agency did not use 99th percentile concentrations because
 such estimates are not as statistically  meaningful when pollutants are only  detected a  few
 percent of the time.  For the non-pollutant-specific data required for this analysis, a sewage
 sludge mgestion  rate of 0.2  g/day, a body weight of 16 kg, and an exposure duration  (for
 cancer) of 5/70 were used.
    „ A      u     rlSk' £ither ™ °ral Risk Reference Dose (RfD) or an oral q, * value was
 needed.  .Of .the 69 pollutants detected less than ten percent of the time, 49 had at least one
 of these estimates of toxicity.  Six of these pollutants had already been evaluated for Pathway
 3 in Round One, and so were not considered further: aldrin, dieldrin. benzo(a)pyrene, DDT
 DDE, and trichloroethene. For the remaining 43 pollutants, EPA estimated risk.  For those
 pollutants with an oral RfD value, the ratio of exposure to RfD was calculated   For those

                         " value' ""• risk  of cancer  was                   '
       As shown in Exhibit A-2, for all but one of the 43 pollutants analyzed, the ratio of
exposure to RfD was. below one and the cancer  risk was below one in 100 000   For 2-
picoline  the ratio of exposure to RfD was  five.  EPA  chose to  not  evaluate 2-picoline
further, however, because it was only detected one percent of the time in the 1988 NSSS
                                        A-l

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   Screening Analysis Based on Cancer Potency Slopes
          The second screening analysis EPA conducted consisted of identifying those pollutants
   with relatively high cancer potency slopes.  As shown in Exhibit A-l, four pollutants, aldrin
   dieldrin, heptachlor epoxide, arid benzo(a)pyrene, have relatively large q,' values.  These
   pollutants were evaluated further.

          Although aldrin and dieldrin are both insecticides, they are often evaluated together
   as aldrm/dieldnn, because dieldrin  is an environmental  degradation product of aldrin   In
   addition, aldrin and dieldrin have the same human health toxicity values.  In Round One
   aldrm/dieldrm were evaluated for Pathways 1 through 11,. but not  12, 13, or 14.

          Given the log(Kow) value for dieldrin is greater than five, aldrin/dieldrin misht pose
   an unacceptable risk by  sorbing to. panicles that subsequently erode and enter  a^stream
   Aldnn/dieldnn is not expected to leach significantly to groundwater, given the high log(AT  )
   value   However, aldrin/dieldrin might also  pose an unacceptable risk through volatilization
   Therefore, EPA evaluated risks from Pathway 12 and Pathway 13. for aldrin/dieldrin using
   the assumptions and equations presented in  Sections 4.2.12 and 4.2.13, respectively.

         To  correspond to the methods used 'in the Comprehensive Hazard  Identification
  exercise, the 95th percentile pollutant concentrations with the non-detect values set equal to
  the minimum detection level  were used.  The pollutant-specific data for both pathways are
  presented in Exhibit A-3.                                             .**..-.

                                      EXHIBIT A-3
                Pollutant-Specific Data Required for Pathways 12 and 13
               95th percentile concentration (mg/kg)
               Kd(L/kg)
Henry's Law constant (atm-m3/mol)
                   (yr1)
Diffusivity in Air (cnr/sec)
              BCF (L/kg)
              FM (dimensiohless)
                                                              5.482
                                                11733
                                                            l.lxlO-5(2)
                                                 O4
                                                             4xl0-2(3)
                                               34003
^ Composite aldrin/dieWrin concentration from 1988 NSSS
' Schwarzenbach et al., 1993.
.  Calculated using equations in Section 4.2.12.
4 Howard, 1991.
                                         A-5

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        Results of the analysis are presented in Exhibit A-4 for Pathway 12 and Exhibit A-5
  for Pathway 13.   For Pathway 12, the individual cancer risks range  from 7xlO'9  for
  reclamation sites to 2X10"8 for other land application sites.  For Pathway 13, individual cancer
  risks range from 9xlO'8 for agricultural land to IxlO"6 for reclamation sites.

                                    EXHIBIT A-4
             Individual Cancer Risks.for Aldrin/Dieldrin from Pathway 12
! Agricultural Land
2xlO'8
Forest
2xlO-8
Reclamation Site
7xlO-9
Public Contact
Site
2xlO'8
                                    EXHIBIT A-5
             Individual Cancer Risks for Aldrin/Dieldrin from Pathway 13
1 Agricultural Land
9xlO-8
Forest
4xlO-7
Reclamation Site
IxlO-6
Public Contact
Site
2xlO'7
       For heptachlor epoxide, the individual risk for a child directly ingesting sewage sludge
(Pathway 3) was calculated above to be 9 x 10'7 (Exhibit A-2). Given the low magnitude of
the risk,  this pollutant was not evaluated further.

       Benzo(a)pyrene" was fully evaluated for all land application pathways in Round One
except Pathway 11 (tractor driver).  Benzo(a)pyrene cannot be considered further in Round
Two for Pathway 11, however, because there is not a Threshold Limit Value for this pollutant
to be evaluated under Pathway 11.
                                       A-6

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               APPENDIX B

           STATISTICAL ANALYSES
OF THE NATIONAL SEWAGE SLUDGE SURVEY DATA

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                    Final Report:

Percentile Estimates Used to Develop the List of Pollutants

       for Round Two of the Part 503 Regulation
                   Submitted to:

          Environmental Protection Agency
          Office of Science and Technology
          Engineering and Analysis Division
              401 M Street, SW. (4303)
              Washington, DC 20460
                  Submitted by:
 Health and Environment Studies and Systems Division
    Science Applications International Corporation
               1710 Goodridge Drive
               McLean, VA 22102
               Contract No. 68-C4-0046
      SAIC Project No. 01-0813-07-5046-010
                                              An-Employee-Owned Company

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   I.   INTRODUCTION

   In Februaiy, 1993, the Environmental Protection Agency (EPA) promulgated limits for nine toxic
   pollutants in sewage sludge.  These limits which were issued by EPA under the authority of
   section 405(d) Clean Water Act, as amended, are referred to as the "Round One" sewage sludee
   regulation. In May, 1993, the EPA submitted to the court a list of 31 candidate pollutants for
   "Round Two" regulations. This report presents percentile estimates used to develop the list of
   pollutants for Round  Two of the Part 503 Regulation.   All elements, compounds, or solids
   physically measured will be referred to in this report as pollutants.  The term pollutant is used
   here to mean only that a substance, in certain quantities, could cause harm to human health or the
   environment; not that it adll cause harm to human health or the environment.
                                 \
   Data analyzed to produce these pollutant concentration percentile estimates are from the EPA's
   1988 National Sewage Sludge Survey (NSSS). Section H briefly describes the NSSS   Data
   conventions are presented in Section m.  Section TV  provides the statistical methodology
   employed to produce me percentile estimates. And finally, Section V presents tabulated percentile
H.   EPA's 1988 NATIONAL SEWAGE SLUDGE SURVEY

To support Round One and Two regulatory development efforts, the EPA's 1988 NSSS collected
sewage sludge quality and pollutant occurrence data from a national probability sample of Publicly

            ^         P°TWS   iaC6
  S±   T ^  ^ (P°TWS) PiaC6^S 3t ^ "*"d«y "-—l °f wastewW
  OperationaUy,  secondary treatment was defined as  a primary clarifier process followed by
  biological treatment and secondary clarification. In 1988, 11,407 POTWs in the 50 States, Puerto
  Rico, and the District of Columbia met this criteria.

  A statistical probability sample of 208  POTWs in the contiguous states and the  District of
  Columbia comprised the analytical component of the 1988 NSSS.  These POTWs were randomly
  drawn from secondary or higher treatment POTWs which were categorized into one of four stZ
  based on their average  daily flow rate.  These strata are defined as follows:

     1)   Flow greater than 100 million gallons per day (MGD)
     2)   Flow more than 10 MGD but less than or equal to 100 MGD
     3)   How more than 1 MGD but less than or equal to 10 MGD
    4)   Flow less than or equal to 1 MGD.

 EPA contract personnel collected  sewage sludge samples from  180 POTWs in the analvtical
                                                                       "
                l                    -                                           ae
        All sample collection and preservation was conducted according toprotocol  Contract
-i^W'VBWV riUdge *** for 412 «**  ipAPadapS'aS
 methods 1624 and 1625 to allow volatile and semi-volatile organic analytes to bTcfuantified
 the .sewage sludge matrix.  Pesticides and polychlorinated biphenyls (PCBs) were
                                         1

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  according to EPA method 1618; method 1613 measured dibenzofiirans and dioxins; metals, other
  inorganics, and classical were quantified according to standard EPA methods.' All chemical
  analysis methods were either developed, chosen, or adapted to allow for the most reliable and
  accurate measurement of the 412 analytes in the sewage sludge matrix.

  A more detailed discussion the NSSS sampling plan, POTWs, and data is included in a November
  1992 final report entitled "Statistical Support Documentation  for the 40 CFR, Part 503 Final
  Standards for the Use or Disposal of Sewage Sludge."

 ffl.     DATA CONVENTIONS

 A total of 208 POTWs were selected for sampling as part of the analytical component of the 1988
 NSSS. However, 32 POTWs were excluded from the statistical analyses because sewage sludge
 samples were not obtained after the completion of secondary treatment of wastewater. POTWs that
 were selected for the NSSS but excluded from the statistical analyses are listed on Table 1 The
 EPISODE number listed on Table 1 designates the POTWs identification number in the analytical
 survey. An episode number of "0" indicates that the POTW was selected for sampling as part of
 the analytical-probability sample but samples of sewage sludge were not collected.

 The reported national pollutant concentration estimates were calculated  from a sample of 176
 POTWs.  These estimates apply to a population of 7,750 POTWs that practiced at least secondary
 treatment of wastewater during 1988. Pesticides were not quantified for Surveylb 35-38-348
 ^SSSSf ° J116"*016' «*»*» f°r pesticides reported on the tables result from a sample
 of 175 POTWs and are projected to a population of 7,720 POTWs in the Nation. Sewage sludge
 samples from SurveylDs 23-07-036 (Episode =1554) and 35-05-012 (Episode=1561) were not
analyzed  for the dioxin/furans. Therefore the dioxin estimates, generated from a sample of 174
   ^S>, "5 { ? a P0?"1^011 of 7'714 POTWs- Adjusted stratum weights for each sample size
are tabulated below.                                                              •


                ADJUSTED WEIGHTS for STRATA (wj) by Sample Size
                     Sample size = 174
                        »i_-_»_^_i

                         27/7,714
                         301/7,714
                        1,838/7.714

                        5,548/7,714
Sample size = 175
    ——^____
    27/7,720

    307/7,720
   1,838/7,720
Sample size = 176
    -5=5S=__S

    27/7,750
                                                                 307/7,750
   1,868/7,750

-------
   In the NSSS, if a pollutant was measured above the Minimum Level, as adjusted for interferences
   then the measure is considered a detection.  In the August, 1989 document titled "Analytical
   Methods for the National Sewage Sludge Survey," the EPA's Industrial Technology Division
   defines a Minimum Level for pollutants quantified by gas chromatography combined with mass
   spectrometry (GCMS) as the level at which " the entire analytical system shall give recognizable
   mass spectra and acceptable calibration points."  For elemental pollutants, the Minimum Level
   is defined as "the minimum concentration of substance that can be measured and reported in 99%
   confidence that the value is above zero." The final report for Round One Part 503 regulations
   refers to the Minimum Level as "roughly equivalent to the minimum concentration or amount of
  pollutant that could be measured."

  If a pollutant was not measured above the Minimum Level, then estimates were generated using
  two substitution methods.  One set of estimate were produced using the value of the Minimum
  Level for those samples for which the pollutant was considered to be an non-detect The second
  set of estimates substituted zero for pollutant concentration value for those samples from which
  a pollutant was not quantified above the  Minimum Level.  Tabulated results identify the
  substitution method employed  for the reported set of estimates.

  Prior to calculating the estimates, pollutant concentrations were aggregated on a POTW basis to
  form one concentration value per POTW for each pollutant. Field duplicate samples were
  averaged together. For POTWs with multiple treatment trains, sample measuremen^pSlu^
  concentrations were averaged  together, using a weighted average based on the dry weight of
 f ^ t?  T** by ** treatment *** aSSOdated *** «* -Me, Primary sarnp7« f were
                                                                 »  a
 secondary treatment  Because the percent solids in sampled sewage sludge ranged from kn ten
 raf^toofT^^^
 as a function of the sample s percent solids: This transformation allows a standardized basis for
 The  dioxins  and furans  are reported  individually and  in  aggregate    Agereeates were


                                                                         -
first convention  the composite dioxin was considered a detect if all of the individual conveners

a7^S"1rr
SL™ TV-         ^       ^ °f determining a detec*°n for the composite dioxin, the
compete dioxin was considered a detect if at least one of the individual congeners was detiS
           T111"1       T^651^ » ^ignated «dioxinb."  TEF adjusted estimates of the
         congeners appear in Section V.

-------
   PCBs were also mathematically aggregated. These aggregates were generated as described above
   with the exception that the individual PCB's were hot multiplied by a toxicity equivalence factor.

   IV.     STATISTICAL METHODS

   Percentile estimates were calculated using the nonparametric, weighted cumulative distribution
   function (CDF) technique.  Denote the dry weight concentration of a given pollutant in the
   sampled sewage sludge from the j* POTW in the i* survey flow stratum as X,.  The vahjes of the
   variable X,. were then sorted in order of increasing concentration. The values of the adjusted
   sur^w«ghts (Wi) associated with the ordered values of X are then  summed until the first


  If Xp is defined as the concentration of the p* percentile then,
                                                      4
                       X = F(XUp where  F(X) .= £ V.F. (X)
                                                     •^~  J. 2.      „
  with
                                       7=1
                                     and KXg 5 x)    = 1 if X^ £x for x aO
                                                           = 0 otherwise.

 To determine the pollutant concentration associated with the p* percentile, an inverse function was
 applied to the^ cumulative distribution function. Define the D* oercentile as
 P     !,                                                                        a
 PJPtog .p/100 Tneinverseof this function F'(p), is the smallest value of x satisfy   lx),p
 where p is the desired percentile point (P) divided by 100.

 Because the cumulative distribution created by application of the formula in the previous section
 ^empirical, integer valued percentile points are not always realized in the data. The conation

                  ** ^f11^011 aSS°daled ^ ** P* "«*« P6^^6 fi«» *e empiric^
                  was to determine the smaUest concentration value x such that FUx) >p Tto
                       ^^0^ «-—*»• ^ next smallest conc^S^f^m
  nH               f^ wth me (q-Dst ordered concentration was then defined. The
concentetion value for the p* percentile was obtained using linear interpolation between the a*
ana (q-lj values.   ,                             .                                   n

Nonparametric  estimates of pollutant concentration means and standard deviations are also
reported in the tables. Retaining the definition of X, as the dry weight concentration of a. given

-------
   pollutant in the sampled sewage sludge from the j* POTW in the i* survey stratum and w- as the
   adjusted survey weight for the i* stratum, then the mean pollutant concentration was estimated as
   listed on the next page.

£
                                            v
                                                n..
   The poUutant concentration standard deviation was estimated as the square root of the method of
   moments estimator of the variance. That is:
                                                         1/2
                                    •*    "it  y  *•
                         V(X)i/2 =
  V. POLLUTANT CONCENTRATION PERCENTILE ESTIMATES

  Tables 3 and 4 present pollutant concentration percentile estimates for pollutants from the 1988
  National Sewage Sludge Survey (NSSS.) Taking into account the individual dioxin and furan
  congeners  and  the PCS aroclors, Tables 3 and 4  present concentration estimates for 353
  pollutants. The listing of pollutants is ordered by percent detection. The ordering is from highest
  to lowest detection rates in the nation. Excluded from this listing are the metals regulated in
  Round One, and the 42 semiquantitative metals listed on Table 5. Of the 42 semiqukntitative
  metals, 36 had no quantitative measurements recorded in the NSSS database.  Of the remainine
  six, potassium and iodine had one recorded measure while silicon, strontium,  and  sulfur had
TrTZ6"!5 re«)rded/oi;itwo ^P165- AU other samples were missing measurements. This
  precluded estimation of poUutant concentrations.  Estimates of phosphorus concentrations were
  generated from data collected using colorimetric method 365.2 as reported in EPA's August  1989
  Analytical Method for the National Sewage Sludge Survey."

  For each poUutant, the tables report the foUowing:  poUutant type, unit of measure, sample size
 t^*?*^*S* Pf^detect' mean> ^dard deviation, the observed maximL, and
 me w , 9S" 9S», 90"  and  median percentiles estimated from empirical national, cumulative

 rf?S?^fj?° M«^ncen^°f ""*'C0lumn labeled "Sample""records *e number
 of POTWs in the NSSS from which data were used to generate the reported estimates.

 Table 3 is subtitled "Nonparametric  Substitution Method Estimation Procedure - Nondetects Set
 to the Minimum Level."  The nonparametric estimation procedure is that described in Section IV.

-------
The substitution of nondetects set to Minimum Levels indicates that Minimum Level of a pollutant
was used in the estimation procedure for those samples that were not quantified above the
pollutant's Minimum Level of detection.  Estimates on Table 4 were generated using the value
zero for samples from which a pollutant was not quantified above the Minimum Level.

Tables 3 and 4 indicate that there.are 45 tested pollutants detected at an estimated national rate of
ten percent  or higher from sewage sludge resulting from secondary or higher treatment of
wastewater in 1988.   EPA used this list of pollutants in conjunction  with human health and
ecological toxicity data to select the 31 candidate pollutants for Round Two regulation

-------
                                    TABLE 1.
        LISTING OF POTWS EXCLUDED FROM PERCENTILE ESTIMATION
                                                                 FLOW
                                                               STRATUM
SURVEYED
 12-49-455
 ^—"•^•••—™
 21-25-234
            REASON
            ——»••—••••.
 Ineligible/Out of Busing
 Not sampled
 ^••^•^^^M^hvM^H
 Ineligible/Out of Business
 Only primary sludge sampled
    ^^^^^^^^^""^""""^•^•^^•^^"•^^•^M
Data not entered into database
Only orimarv sludge samoled
   25-50-472
       •^—••
   31-18-140
  31-23-206
  41-24-215
  41-36-312
                         Not sampled
                         •••^^••^^^"—••^^MIM
                         Not sampled
                           Wastewater Stabilization pond
                           _._.                  *~
 45-13-083
 "^^^^•"«««"™"l^^^^
 45-13-089
 —•"™«—^«»^_
 45-14-092
 "••''      —
 45-15-112
 45-16-130
 45-17-131
 45-19-154
 ••^•MHHH.
 45-23-208
 45-24-220
 45-25-229
 ^~^"^^"«™^^^-™
 45-25-231
45-26-237
                        Ineligible/Out of Busin^c

-------
45-28-246
45-29-248
45-30-253
45-37-339
45-42-387
45-42-392-
45-45-415
45-45-423
45-50-463
45-50-474
0
0
0
0
0
- 1488
0
0
0
0
WWSP
WWSP
WWSP
Not sampled
Ineligible/Out of Business
Ineligible/Out of Business
WWSP
Not sampled
Not sampled
WWSP
4
4
4
4
4
4
4
4
4
4
8

-------

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                         TABLES




SEMIQUANTTrATIVE METALS in the NATIONAL SEWAGE SLUDGE SURVEY
| CAS NUMBER | CHEMICAL NAME |
I 7440699 1 . BISMUTH j
I 7440451 | CERIUM |j
1 74299.16
1 7440520
' 7440531
7440542
7440553
• 7440564
7440575
7440064
7440097
7440100
7440155
7440166
7440188
7440199
7440202
7440213
7440586
7440600
7440746
DYSPROSIUM II
ERBIUM 1
EUROPIUM 1
GADOLINIUM |
GALLIUM III
GERMANIUM III
GOLD |
PLATINUM I
POTASSIUM I
PRASEODYMIUM |||
	 — 	 ill
RHENIUM |
RHODIUM III
RUTHENIUM |||
.SAMARIUM |
SCANDIUM If
SILICON I
— "' 	 lil
HAFNIUM I
HOLMIUM |
INDIUM If
| CAS NUMBER 1 CHEMICAL NAME
1 7440246 j STRONTIUM
7704349
7440257'
13494809
7440279
7440291
7440304
7440337
7440611
7440031
, 7440644
7440042
7440677
7440053
7723140
7553562
7439885
7439910
7439932
7439943
7440008
SULFUR
TANTALUM
TELLURIUM
TERBIUM
THORIUM
THULIUM
TUNGSTEN
URANIUM
NIOBIUM
YTTERBIUM
OSMIUM
ZIRCONIUM:
PALLADIUM:
PHOSPHORUS
IODINE
IRIDIUM
LANTHANUM
LITHIUM
LUTETIUM
NEODYMIUM
                          46

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          APPENDIX C

CALCULATION OF A "SQUARE WAVE"
FOR THE GROUNDWATER PATHWAY

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          Potential human exposure and risk through the groundwater pathway are estimated for
   VAnn^T apP'1C,ati°n ai?d surfacfe disP°saI  of sewa^ sludge.   To prepare input for  the
   VADOFT model of pollu£am ^p^ ^^ ^ unsaturated 2one  k ig conservativej
   assumed for both land application and surface disposal that the pollutant is consistently loaded
   into the top of the unsaturated  zone at the  maximum rate estimated by  mass  balance
   calculations. The.duration of this constant pulse, or "square wave", is constrained so fl«£
   total mass of pollutant leaching or seeping from the site is conserved.  Althoush the general
   approach is the same for both land application and surface disposal, details differ aSne
   to which management practice is being considered. This append provides a brief dTscuSon
   of Ac methods for estimating the magnitude and duration of the  "square wave" of poHumm
   loading for land application and both prototype facilities for surface disposal
  Land Application
        Both inorganic and organic pollutants can accumulate in soil with repeated applicatio
  of sewage sludge.  As described in Chapter 4, it is assumed that all compel?poSumnt
  processes for sewage sludge-amended soil can be approximated as firsSfrder  and
  coefficients describing the rate of loss to each process can be summed to
   lumped" coefficient for first-order loss.  Losses at any time , can then te
                                   dMt
 where:
       M,    -     mass of pollumnt in sewage sludge-amended soil at time t (kg) and
       K,0,    -     total loss rate for the pollutant from sewage sludge-amended soil (yr>).
                       Mt = fpA  e~K^ dx =
                            o                K.
where:
      PA
                    total annual loading of pollutant to site (kg/yr).

Aw approaches inflnity, M, therefore app^ches (PA,/Km and yearly loss approaches yearly
                                       C-l

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                soil.  Estimates of risks from organic pollutants on land application sites are derived for this
                steady-state condition.  The amplitude of the square wave pulse for the groundwater pathway
                model is therefore equal to the annual loading of pollutant multiplied by the fraction of annual
                loss attributable to leaching,  the length of the square wave is equal to the length of the
                simulation (300 years).

                      For inorganic pollutants, this condition of steady-state is not necessarily reached.  The
                leaching of inorganic pollutants from sewage sludge to groundwater depends not only on the
                cumulative loading of inorganic pollutants, but also on the period of time  in which this
                cumulative loading takes place.   It  is  assumed that,  after 20 years, applications are
                discontinued.  To capture the risks associated with the peak rate at which inorganic pollutants
                leave the soil layer, the peak loss rate (calculated for the 20th year of application) is used for
                the  calculations.   The  length of the square  wave is  calculated by dividing  the  total
                (cumulative) loading of pollutant by this maximum rate of loss:            • •"


                                          TP =     N PA     =      N
                                                PA (l-e~K^)    (1-

               where:
                      TP    =     duration of "square wave" for approximating the loading of pollutant
                                   into the unsaturated soil zone (yr).

                                            '
               ---------- c --- ________ „ *.«wtJFt

                     The modeling of the groundwater pathway  for the monofill prototype of surface
               disposal is similar to that for land application.   For both cases, it is assumed that the site
               receives repeated loadings of pollutant for the duration of its active lifetime. By analogy with
               the above discussion for land application, this maximum rate of loss from the facility can be
               described as a function of its yearly loading, yearly loss, and number of years of active
               operation:
                                            *„**„* PA tl-e-*-")

              where:
                     LF    =      active lifetime of monofill (yr),
                     to,*    =     .mass of pollutant in sewage sludge/soil at  end of monofill's active
                                   lifetime (kg), and
                     PA     =      total annual loading of pollutant to monofill  (kg/yr).
•
                                                       C-2

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  The length of time this maximum rate of loss could be maintained is then:
                           TP =-
                                    LF PA            LF
                                PA'a-e'*-1*)    1-e-*-^



 Surface Disposal: Surface Impoundment Prototype

        For the surface impoundment prototype of surface disposal, calculations are based on
 the conservative assumption that steady-state is maintained for concentrations of pollutants
 within the liquidI and sediment layers of the impoundment. It is also assumed that the flux
 of pollutant leaching from the impoundment is constant with respect to time, at least until the
 tota mass of pollutant deposited in the impoundment has been depleted  For this orototvne
 the length of the square wave used for execution of the VADOFT model is therefore eaual
 to the total mass of pollutant entering the impoundment each year, multiplied by the expected
 lifetime of the facility and divided by the amount lost each year-                 expected
PA
                          31,536,000  -PA •/„   31,536,000  -/^

where:

                          total annual loading of pollutant into  the surface impoundment
                          \*v§' j*/»
                          estimated active lifetime of surface impoundment (sec),
                          constant to convert (sec) to (yr), and
                          fraction of each year's loading of pollutant lost during each year
                          of the surface impoundment's active phase (dimensionless)
                                      C-3

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                APPENDIX D

    EVALUATION OF CANDIDATE POLLUTANTS
FOR THE ROUND TWO SEWAGE SLUDGE REGULATION

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EVALUATION OF CANDIDATE POLLUTANTS FOR THE
   ROUND TWO SEWAGE SLUDGE REGULATION
                      by
     U.S. ENVIRONMENTAL PROTECTION AGENCY
               401 M STREET, S.W.
             WASHINGTON, D.C. 20460
                  AUGUST 1996

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                        TABLE OF CONTENTS


                                                                           Page

 TABLE OF CONTENTS . .	 .	      ;



 1. INTRODUCTION .		   j


       1.1 Background	             -       j


       1.2 Purpose	 .	                   2


      . 1.3 Policy Decisions	             2


       1.4 Additional Information	       3



2.  POLLUTANT EVALUATIONS	                  4


      2.1  Candidate Pollutants That Warrant Consideration	     4


      2.2  Information Used to Develop Rationales to Exclude
            Inorganic Pollutants From Further Consideration	      6


            2.2.1  Land Application	                    7


            2.2.2  Surface Disposal ......	                       -12


      2.3  Rationales for Excluding Inorganic Pollutants From
            Further Consideration	            12


            2.3.1 Land Application . . . . .  ;	             « -  .    j^


            2.3.2 Surface Disposal	                28


            2.3.3 Incineration	              29


     2.4  Pollutants Recommended by Others for the Round Two
            List of Pollutants 	

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                TABLE  OF CONTENTS (cont'd)

                                                                   Page

3. LIST OF POLLUTANTS FOR THE ROUND TWO SEWAGE SLUDGE
   REGULATION	32


4. REFERENCES	 . 34
APPENDIX Dl:    List of 31 Candidate Pollutants for the Round Two Sewage Sludge
                 Regulation Submitted to the District Court in Oregon
APPENDIX D2:    Final List of Pollutants for the Round Two Sewage Sludge Regulation
                " Submitted to the District Court in Oregon
APPENDIX D3:    Responses to Requests for Data on the Round Two Candidate Pollutants
                                   11

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                              1.  INTRODUCTION




  1.1  BACKGROUND




        In 1987, Congress amended section 405 of the Clean Water Act (CWA) to require a




  comprehensive program to reduce the potential public health and environmental risks from the




  use or disposal of sewage sludge, which is solid, semi-solid, or liquid residue generated during




  the treatment of domestic sewage in a.treatment works. Amended section 405(d) established a




  timetable for the development of the sewage sludge use or disposal regulations. The basis for




  the program Congress mandated to protect public health and the environment is the development




  of technical requirements or standards for sewage sludge use or disposal, and the implementation



  of the standards through a permit program.




        Under the current section 405(d), EPA first had to identify toxic pollutants that may be




 present in sewage sludge in concentrations that may affect public health and the environment.




 Next, for each identified use or disposal practice, EPA had to publish regulations  that specify




 management practices for sewage sludge that contains the toxic pollutants and establish numerical




 limits for the toxic pollutants.  The management practices and numerical limits must be "adequate



 to protect public health and the environment from any reasonably anticipated adverse effect of




 each pollutant." Section 405(d) requires that EPA publish the sewage sludge regulations in two




 rounds and then review the regulations periodically to identify additional pollutants for regulation.




       On February 19, 1993, EPA .published the Round One sewage sludge regulation (i.e., the




 Standards for the Use or Disposal of Sewage Sludge - 40 CFR Part 503)in the Federal Register




(58 FR  9248).   It was amended  subsequently on February 24, 1994 (59 FR  9095), and on



October 25, 1995 (60 FR 54164).       .

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        A candidate list of pollutants for the second round of the sewage sludge regulations (i.e.,

 Round Two) was provided to the District Court in Oregon in May 1993 (see Appendix Dl). The

 final list of pollutants was submitted to the District .Court in Oregon  in November  1995 (see

 Appendix D2).  The Round Two sewage sludge regulation is scheduled for proposal in December

 1999 and for publication in December 2001.

        To develop the final list of pollutants for the Round Two  sewage sludge regulation, a

 Comprehensive Hazard Identification study was conducted by use or disposal practice for the 31

 pollutants on the candidate list.  Results of that study were used to determine the candidate

 pollutants that warrant further consideration for the Round Two list of pollutants.



 1.2 PURPOSE

       This paper reviews the candidate pollutants from the Comprehensive Hazard Identification     ^^

 study that warrant further consideration  for the Round Two list of pollutants and presents the

 rationales for not including some of the pollutants on the final list. It also presents the pollutants

 on the final  list of pollutants for the Round Two  sewage  sludge regulation.



 1.3    POLICY DECISIONS

       For the review of the candidate pollutants from the Comprehensive Hazard Identification

study that warrant further consideration for the  Round  Two list, EPA made  several  policy

decisions. They are:

      •      Uptake rates from non-sewage sludge studies (i.e., crops for which the uptake rates
             were obtained were not grown in sewage sludge-amended soil) are not appropriate
             for crops  grown in sewage sludge-amended soils  because  sewage sludge  is
             expected to  "bind" pollutants and  makes them less  available for plant uptake

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              (Corey et al., 1987).                 .                          '

              Potential population effects are of greater concern than are individual effects for
              exposure  pathways  in which  the  Highly  Exposed  Individual  (HEI)  is a
              nonendangered animal.

              The route through which a pollutant is administered (e.g., in drinking water or
              food) hi a toxicity study should be considered when determining the applicability
             . of the study to an exposure pathway.

              A soil type for all land application sites and surface disposal sites of either sandy
              loam, shrinking clay, or sand is reasonable.

              A margin of safety that is smaller than the total uncertainty factor used for the
              Reference Dose (RfD) is reasonable in .certain cases.
1.4 ADDITIONAL INFORMATION

       Questions about the information in this paper should be addressed to:

             Yogendra M. Patel or Robert M. Southworth
             U.S. Environmental Protection Agency (4304)
             401 .M Street, S.W.
             Washington, D. C.  20460

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                    2. POLLUTANT  EVALUATIONS





  2.1 CANDIDATE POLLUTANTS THAT WARRANT CONSIDERATION




         During the Comprehensive Hazard Identification study (U.S. EPA, 1996), 15 exposure



  pathways were evaluated for land-applied sewage sludge and two pathways were evaluated for



  sewage sludge placed  on a  surface disposal site. A pathway was considered "critical" for a




  pollutant if the risk level for a carcinogenic pollutant was W4 or higher; the ratio of exposure




  for a noncarcinogeriic pollutant to its Reference Dose (RfD) was equal to or greater than one; or




  the risk quotient (RQ)  for a  pollutant for the ecological pathways was equal to or greater than
 one.
        Based on the results of the Comprehensive Hazard Identification study several of the




 candidate pollutants had critical pathways for land application and for surface disposal.  The




 candidate pollutants and their critical pathways are presented in Table 2.1 for land application and




 Table 2.2 for surface disposal. The exposure pathway for incineration (i.e., inhalation) was not




 critical for any of the candidate inorganic pollutants.   That pathway was not evaluated for the




 organic pollutants because organic pollutants are controlled by the allowable concentration of total




 hydrocarbons in the exit gas from a sewage sludge incinerator in the Part 503 regulation.




       As indicated on Tables 2.1 and 2.2, dioxins, dibenzofurans, and coplanar polychlorinated




 biphenyls (PCBs) have  several critical  pathways.    For this reason  and because dioxins,




 dibenzofurans, and coplanar PCBs are bioaccumulative pollutants (i.e., they accumulate in human




 and animal tissues) with reproductive effects, EPA concluded that those pollutants should be on




the final Round Two list of pollutants for land application and surface disposal.

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   TABLE 2.1 - POLLUTANTS WITH CRITICAL LAND APPLICATION PATHWAYS
Pollutant
Aluminum
Antimony
Barium
Beryllium
Boron
Dioxins/furans
Fluoride
Manganese
PCBs - coplanar
Thallium
Tin
Titanium
Critical Ag Pathway
6
7,14 .
7,10,14
14

2,3,10,12,13,15
6,10
3,6,7,14
3,4,5,6,15
3
7
6
Critical Non-Ag Pathway
6(f,r,p)
7(f,r); 10(f,p); 14(f,r,p,)
7(f,r); 10(f,r,p); 14(f,r,p)
H(f,r,p)
6(f,p)
3(f,r,p); 10(f,r,p); 12(f,r,p);
13(f,r,p); 15(f,r,p)
6(f,r,p); 10(f,r,p)
3(f,r,p); 4(f,r); 6(f,r,p); 7(f,r);
10(f,p); 14(f,r,p)
3(f,r,p); 4(f,r); 5(f,r); 6(f,r,p);
13(f,r); 15(f,r,p)
3(f,r,p)
7(f,r)
6(r).
Pathway 2 - residential home gardener
Pathway 3 - child ingesting sewage sludge
Pathway 4 - human ingesting animal products (foraging animals)
Pathway 5 - human ingesting animal products (grazing animals)
Pathway 6 - livestock ingesting forage/pasture
Pathway 7 - livestock ingesting sewage sludge
Pathway 10 - soil organism predators ingesting soil organisms
Pathway 12 - humans ingesting surface water and fish
Pathway 13 - humans inhaling volatilized pollutants
Pathway 14 - humans ingesting groundwater
Pathway 15 - breast-feeding infant
f - forest; r  - reclamation site; p - public contact site; ag - agricultural land; non-ag - non-
agricultural land

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   TABLE 2.2 - POLLUTANTS WITH CRITICAL SURFACE DISPOSAL PATHWAYS
   Pollutants
Monofills
Surface Impoundments
   Antimony
                   Ground water
   Barium
                                                Ground water
   Beryllium
                   Ground water
   Dioxins/furans
                   Air
   Manganese
                   Ground water
        EPA also  concluded  that the inorganic  pollutants with critical  pathways for  land




 application and surface disposal should not be on the final list of pollutants for the Round.Two




 regulation.  The rationales for excluding those pollutants from the list are presented below.
 2.2 INFORMATION USED TO DEVELOP RATIONALES TO EXCLUDE INORGANIC




 POLLUTANTS FROM FURTHER CONSIDERATION




       The Comprehensive Hazard Identification study used to evaluate the candidate inorganic




 pollutants was, by design, conservative.  After the critical pathways were identified for each




 pollutant, a detailed examination of each pathway was conducted by EPA to confirm that the




 pathway results supported inclusion of the pollutant on the final Round Two  list of pollutants.




       As part of the detailed examination for each critical pathway for a pollutant, three reviews




 were conducted.  First, the assumptions made in conducting the pathway exposure assessment




 were reviewed. Next, the relevance of available toxicity data for a pathway to the Highly




Exposed Individual (HEI) for the pathway was reviewed. Finally, the magnitude of the ratio of




estimated exposure to the RfD for a noncarcinogenic pollutant in the non-ecological pathways
                                                     or
                                         6

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 the magnitude of the ratio of the estimated exposure to the toxicological reference value (TRV)




 for a pollutant in the ecological pathways was reviewed.








 2.2.1 Land Application           •                 .




       The information in Tables 2.3, 2.4, 2.5, and 2.6 was used in the detailed examination of




the critical land application pathways.  Table 2.3 contains a summary of conservative assumptions




for several of the critical pathways.  Table 2.4 contains the Highly Exposed Individual (HEI) for




each of the  critical pathways, and Table 2.5 contains the measurement endpoint for each pollutant




by critical pathway and the species used to develop the endpoint.  Table 2.6 contains the results




of the Comprehensive Hazard Identification study for each of the critical pathways.

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TABLE 2.3 - SUMMARY OF CONSERVATIVE ASSUMPTIONS
Pathway
.3
4
6
. 7
10
14
Conservative Assumption
One hundred percent of the material that the child ingests is sewage sludge,
not a mixture of soil and sewage sludge.
Results from non-sewage-sludge studies can be used to develop pollutant
uptake slopes into forage/pasture.
Herbivorous livestock or small herbivorous animals forage only on land on
which sewage sludge has been applied; results from non-sewage-sludge
studies can be used to develop pollutant uptake slopes, into forage/pasture.
Herbivorous livestock graze only on land on which sewage sludge has been
applied.
All of the soil organisms ingested by small mammals are exposed to sewage
sludge-amended soil and, therefore, bioconcentrate pollutants.
The soil-water partition coefficient used is the lowest soil-water partition
coefficient for sandy soil with a porewater pH of 5.

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TABLE 2.4 - HIGHLY EXPOSED INDIVIDUALS FOR CRITICAL PATHWAYS
Pathway Number
3-agricultural
3-non-agricultural
4-non-agriculturaI
6-agricultural
6-non-agricultural
7-agricultural
7-non-agricultural
10-agricultural
1 0-non-agricultural
14-agricultural
1 4-non-agricultural
Highly Exposed Individual (HEI)
Child ingesting sewage sludge
Child ingesting, sewage sludge
Human uigesting deer and elk
Herbivorous livestock
Herbivorous livestock (forest, reclamation site); small
herbivorous mammal (forest, public contact site)
Herbivorous livestock
Herbivorous livestock
Small insectivorous mammal ingesting soil organisms
Small insectivorous mammal ingesting soil organisms
Human ingesting ground water
Human ingesting ground water

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TABLE 2.5 - MEASUREMENT ENDPOINTS FOR CRITICAL PATHWAYS
Pollutant
Aluminum
Antimony
Barium
Beryllium
Boron
Fluoride
Manganese
Thallium
Tin
Titanium
Pathway Number
6
7
10
. 14
7
10
14 •
3
14
.6
6
10
3
4
6
7
10
14
3
7
6
Endpoint/Species '
TRV/rat
TRV/rat
TRV/rat
RfD/rat
TRV/rat
TRV/rat -
RfD/human
CRL
CRL
. TRV/dog
TRV/mice
TRV/mice
RfD/human
RfD/human
TRV/rat
TRV/rat
TRV/rat
RfD/human
RfD/rat
TRV/rat
TRV/mice
1 CRL - cancer risk level
 RfD - risk reference dose
 TRV - toxicological reference value
                              10

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 TABLE 2.6  -  RESULTS OF RISK ASSESSMENT FOR CRITICAL PATHWAYS
Pollutant
Aluminum
Antimony
Barium
Beryllium1
Boron
Fluoride
Manganese
Thallium
Tin
Titanium
Pathway Number
6(ag,i>,p)
7(ag,f,r)
10(f,p)
14(ag,f,r,p)
7(ag,f,r)
10(ag,f,r,p)
14(ag,f,r,p)
14(ag,f,r,p)
6(f,p)
6(ag,f,r,p)
10(ag,f,r,p)
3(ag,f,r,p)
4(f,r) .
6(ag,f,r,p)
7(ag,f,r)
10(f,p)
14(ag,f,r,p)
t
3(ag,i>,p)
7(ag,f,r)
6(ag,r)
RfD Ratio1
'
20(ag),40(f),3(r),60(p)
9(ag),20(f),l(r), 20(p)
7xlO-4(ag),9xlO-4(f)
SxlO-VXlxlO-fa)
'
-
4(ag,p),3(f,r) '
10(f), 40(r)
700(ag),1000(f),
30(r),2000(p)
2(ag,p),l(f,r)
-
•
RQ2
80(f,p),
100(ag,r)
l(ag,f,r)
3(f,p)
40(ag,f,r)
10(ag,r), 50(f,p)
_
4(f,p)
10(ag,r),30(f,p)
5(ag,r),8(f,p)
200(ag,r),800(f,p)
l(ag,f,r)
2(f,p)
-
2(ag,f,r)
7(ag,r)
'Ratio of estimated exposure to Reference Dose (RfD). For beryllium, the value is a carcinogenic
risk level.
2Risk Quotient - ratio of estimated exposure to Toxicological Reference Value (TRY).

ag - agricultural land; f - forest land; r - reclamation site; p - public contact site
                                       11

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  2.2.2 Surface Disposal

        During the Comprehensive Hazard Identification study for surface disposal, soil-water

  partition coefficients for sand with a porewater pH of 5 were used for the ground-water pathway.

  This is the same conservative assumption that was used in the groundwater pathway analyses for
  land application.

        Results of the Comprehensive Hazard Identification study for the critical surface disposal
  pathways are presented in Table 2.7.


     TABLE 2.7 - RESULTS FOR CRITICAL SURFACE DISPOSAL PATHWAYS
Pollutant .
Antimony
Barium
Beryllium
Manganese
Pathway
Ground water
Ground water
Ground water
Ground water
Cancer Risk Level
-
,
2 x 10-4
.
•RfD Ratio1
• 4
1
-
90
               *
 '.Ratio of estimated exposure to the Reference Dose (RfD).



2.3 RATIONALES FOR EXCLUDING INORGANIC POLLUTANTS FROM FURTHER

CONSIDERATION

      The rationales for excluding inorganic pollutants from the list of pollutants for the Round

Two sewage sludge regulation for land application and ^surface disposal are presented below.
                                       12

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 2.3.1 Land Application                                                                      ^^




 Aluminum




        The critical pathway for aluminum for land application is Pathway 6 (animal foraging)




 for both agricultural land and non-agricultural land (forest, reclamation sites, and public contact




 sites).  As indicated in Table 2.3, the uptake slopes used in the Pathway 6 analyses were obtained




 from.non-sewage sludge studies (i.e., crops from which the uptake slopes were obtained-were not




 grown in sewage sludge-amended soil).  EPA concluded it is not appropriate to use those uptake




 slopes to estimate the uptake of aluminum into forage grown in sewage sludge-amended soils (see




 Policy Decision on page 2).  No other information was available on uptake slopes for aluminum.




        Because aluminum is not a bioaccumulative pollutant (i;e., does not accumulate in human




 or animal tissue); because Pathway 6 was the only  critical pathway for aluminum from the




 Comprehensive Hazard Identification study; and because after the detailed review of Pathway 6,




 it could not be evaluated using available information, EPA concluded that aluminum should not




 be on the list of pollutants for the Round Two regulation for land application.








 Antimony




        One of the critical pathways for antimony for land application is Pathway 7 (grazing




 animal that ingests sewage sludge directly). As indicated in Tables 2.3 and 2.5, the measurement




 endpoint (i.e., the lexicological reference value (TRY)) for this pathway for both agricultural and




non-agricultural land is based on results of studies using laboratory animals  (i.e., rats).  This




endpoint was  extrapolated to the  appropriate HEI (i.e., herbivorous animals) for the  land



application risk assessments.
                                          13

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         The lowest observed adverse effect level (LOAEL) for antimony is 0.262 mg/kg-body




  weight/day, which is based on the results of a study in which antimony was fed to rats in water




  (Schroeder et al., 1970). This value was converted to a dietary value (i.e., 3.4 mg/kg-food) using




  a standard body weight of 0.4 kilograms for a rat and allometric equations (U.S. EPA, 1988).




  A decrease in survival and longevity for male and female rats  was observed at this dose




  equivalent.  The dietary value was  divided by 10 to obtain the TRY for antimony.




        There are two reasons why it is not appropriate to use the TRV for laboratory animals as




  the TRV  for the HEI in the Pathway 7 exposure analyses for agricultural land, forests and




  reclamation  sites. First, the study  on which the LOAEL for antimony was based (Schroeder,




  1970) indicates that the effect from  exposure to antimony (a decrease.in survival and longevity)




 occurs later in the life of a rat and growth was not affected.  Thus, the potential for antimony to




 interfere with growth and reproduction (i.e., population effects) is unclear,  Also, results of




 another  study (Schroeder et al.,  1968a)  indicate a decrease in  survival and longevity due to



 exposure to antimony was not observed in mice.




       Second, the LOAEL on which the TRV is based was obtained from a study in which




.antimony was fed to rats in water. Gastrointestinal absorption of antimony in food is expected




to be lower than the gastrointestinal absorption of antimony in drinking water. For example,




results of other rat studies (Sunagawa, 1981; Smyth and Thompson, 1945) in which antimony was




administered  in food indicate that the no observed adverse effect level (NOAEL) for antimony




can be as high as 200 mg/kg-day and not cause  specific systemic effects (e.g., changes in blood




pressure). This value, which did not result in population effects, is over two orders of magnitude




higher than the LOAEL used to develop the TRV for antimony.
                                          14

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         Because there is uncertainty in the animal studies about whether exposure to antimony




  causes population effects and because the LOAEL used to develop the TRY is based on the




  results of a study in which rats were fed antimony in water, EPA concluded that it is not




  appropriate to use the TRY in the Comprehensive Hazard Identification study in the Pathway 7




  analyses.  In those analyses, the HEI ingests sewage sludge while gracing on sewage sludge-




  amended soil.  Other TRY values would likely be much higher based on other toxicity data. If




  the TRY is based on a NOAEL of 200 mg/kg-day (i.e., the NOAEL. from rat studies in which




  rats were fed antimony in food), the risk quotient for the Pathway 7 analyses would be less than




  one.  For these reasons, EPA concluded that antimony should not be on the Round Two list of




  pollutants based on exposure through Pathway 7.




        Pathway 10 (predator of soil organism) also was critical for antimony for land application.




  EPA  concluded that the TRY used in the Comprehensive  Hazard Identification study is not




  appropriate for this pathway for the same reasons the TRY for Pathway 7 is not appropriate.




1  Given that the RQ was 3 and that other TRY values would likely be much higher based on other




 toxicity data, EPA concluded antimony should not be included on the final Round Two list of




 pollutants for land application based on exposure through Pathway 10:




        Pathway  14 (i.e.,  ground  water)  in the. land  application Comprehensive  Hazard




 Identification study for agricultural land and non-agricultural land also was critical for antimony.




 One way to evaluate the RfD ratio for this pathway (i.e., the highest'ratio is 60 for public contact




 sites) is to consider the uncertainty factor for the RfD with respect to .the RfD ratio and the effect



 upon which the RfD is based.




     -  The antimony RfD is based on an uncertainty factor of 1000 (IRIS, 1996). The highest
                                          15

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  RfD ratio for this pathway is 60 for public contact sites. In this case, the margin of safety (that




  is, the ratio between the uncertainty factor and the RfD ratio) is approximately 17 (i.e., 1000/60).




  EPA concluded that a margin of safety of 17 is sufficiently protective for the HEI (i.e., human)




  in this case because .the effect upon which the RfD is based (i.e., changes in cholesterol and




  glucose blood levels) is not severe and is likely reversible. EPA also concluded that the margins




  of safety for the other types of land application sites (i.e., 50 for agricultural land, 25 for forest,




  and 333 for reclamation sites) are protective for the HEIs for those types of land application sites.




        The above information indicates that the critical pathways from the Comprehensive Hazard




 Identification study should not be used as  the basis for including antimony on  the  Hst of




 pollutants for the Round Two sewage  sludge regulation.  For this reason, antimony was not



 included on the list for land application.








 Barium




       One of the critical  pathways for barium for land application was  Pathway 7 (grazing




 animal that ingests sewage sludge directly).  The TRY  for this pathway for agricultural land,




 forest, and reclamation  sites is based on results of studies using  laboratory animals (i.e., rats).




 This endpoint was extrapolated to the appropriate HEI (i.e., herbivorous animals) for the land



 application risk assessments.'




       Study results reported in the Agency for toxic Substances and Disease Registry (ATSDR,




 1992a) were used as the  basis for the TRY for barium.  In those studies (Perry et al., 1983, 1985,




 1989), barium was fed to rats in drinking water. The NOAEL for barium was 0.056 mg/kg- body




weight/day,  which corresponds to a concentration  in drinking water of 1  ppm.  The dietary
                                           16

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 equivalent is 0.7 mg/kg-food when the NOAEL is converted using allometric equations (U!S.




 EPA, 1988).




        The RQ for barium for Pathway 7 was 40. .Even if the LOAEL were used as the basis




 for the TRY, instead of the NOAEL, the RQ would be 4. This means that the estimated exposure




 for Pathway 7 could cause the LOAEL to be exceeded.




        The effect for the LOAEL for barium is an increase in systolic blood pressure.  This effect




 was not seen, however, until the eight month of a 16 month rat study. No other toxic effects




 were observed in the study, and growth was not impaired.  The impact of slight increases hi




 systolic blood pressure for cattle, other grazing animals, and small mammals is unclear, and




 population effects (i.e., growth, reproductive, and mortality) for those animals cannot be evaluated



 using the results of the rat study.




         A 1975 study found reduced life span in male mice given 5 ppm barium in drinking      _




 water (Schroeder and Mitchener, 1975). The calculated LOAEL for this study was 0.95 mg/kg-     ^^




 body weight/day, which has a dietary equivalent of 4.8 mg/kg-food when converted using an




 allometric equation (U.S. EPA, 1988). During the study, longevity only was reduced slightly.




 Other studies in which cardiovascular and other systemic effects from exposure to barium were




 evaluated found NOAELs at an order of magnitude higher than in the NOAEL based on the




 results of the Perry et al. studies.




       EPA concluded that it is not appropriate to use the above TRY as the TRY for the HEI




 in the Pathway 7 exposure analyses because the observed effects from exposure to barium, which




is a non-bioaccumulative pollutant, were not population effects. In addition, the effects tirat were




observed (i.e., increase hi systolic blood pressure) occurred as a result of exposure to barium in
                                          17

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  drinking water. The absorption of barium in drinking water is likely to be higher than absorption




  of barium in food or in sewage sludge.  For these reasons, EPA concluded that barium should




  not be on the Round Two list of pollutants for land application based on exposure through



  Pathway 7.




        Pathway 10 (predator of soil organism) also was critical for barium hi the Comprehensive




 Hazard Identification study for agricultural land and non-agricultural land.  EPA concluded that




 the TRY used in that study for Pathway 10 is not appropriate for the same reasons the TRY for




 Pathway 7 is not appropriate.  Therefore, EPA concluded barium should not be on the Round




 Two list of pollutants based on exposure through Pathway 10.




       Pathway 14 (i.e., ground water) also  was critical for barium for agricultural and  non-




 agricultural land application.  Two conservative assumptions  were made for this pathway in the




 Comprehensive Hazard Identification study. One was the type of soil at the land application sites




 and the other was the value for the soil-water partition coefficient (KJ.




       The type of soil affects the ability of a pollutant to move vertically to an aquifer and




 laterally to a nearby  well.  Soil types in the unsaturated zone beneath a land application site in




 order of increasing pollution potential are: (1) nonshrinking clay,  (2) clay loam, (3) silty loam,




 (4) loam, (5)  sandy loam, (6) shrinking clay, (7) sand, (8) gravel, and (9) thin or absent soil (U.S.




 EPA, 1992).  EPA concluded that it is  reasonable to assume a soil type of either sandy loam,




 shrinking clay, or sand as the soil type for all  land application sites. In the  case of barium, the




 assumed soil  type for the land application sites was sand.




       The Kd value for  sand with a porewater pH of 5 varies from 6 liters per kilogram to  174




liters per kilogram (Gerritse et al., 1982).  In the Comprehensive Hazard Identification study,
                                          18

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  Pathway 14 was critical for barium because the lower end of the Kj range (i.e., 6) was used to




  estimate exposure from barium. If the upper end of the K,, range (i.e., 174) is used, Pathway 14




  is not critical (i.e., the RfD ratio is less than one) for barium.




        EPA concluded that because there is an acceptable range of partition coefficients, it is




  appropriate to use the upper end  of the range, particularly when the  soil type for all land




  application sites is assumed to be sand. Because Pathway 14 is not critical when the upper end




  of the partition coefficient range is used, EPA concluded that barium should not be on the Round




  Two list of pollutants for land application based on exposure through Pathway  14.




        The above information indicates that after the detailed examination of the critical pathways




 for barium (i.e., 7, 10, and 14) in the Comprehensive Hazard Identification study, none of the




 pathways are critical for both agricultural land and non-agricultural land. For this reason, barium




 was not included on the final list of pollutants for the Round Two regulation for land application.








 Beryllium                              .




       Pathway 14 was critical  for beryllium  for both agricultural and  non-agricultural  land




 (forest, reclamation sites, and publication sites). As mentioned previously,  the assumed soil type



 and the partition coefficient are important for this pathway.




       In the case of beryllium, the assumed soil type for all land application, sites is sand.  This




 is a reasonable assumption, particularly for agricultural land. Loam soils (sandy loam, silty loam,




 silty clay loam) are predominant on agricultural land throughout the United States  (sand and




sandy  loams predominate  in the southeast).  Of the loam soils, sandy loam has the highest



pollution potential  (U.S. EPA,  1992).                           ,
                                          19

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        During the Comprehensive Hazard Identification study, the partition coefficient at the




 lower end of the range of partition coefficients for sand with a porewater pH of 5 was used.




 EPA concluded that because a reasonable soil type was used, it is appropriate to use any of the




 partition coefficients in the range of partition coefficients.




        When the median partition coefficient value for sand with a porewater pH of 5 is used.




 Pathway 14 is not critical for beryllium (i.e., the cancer risk level is lower than 10"4).  For this




 reason, beryllium was not included on the final list of pollutants for the Round  Two sewage




 sludge regulation for land application.








 Boron




       The critical pathway for boron for land application is Pathway 6 (animal foraging) for




 forest and reclamation sites. None of the pathways for agricultural land were critical for boron".




       The uptake slopes used hi the Pathway 6 analyses were obtained from non-sewage-sludge




 studies (i.e., crops for which the uptake slopes were obtained were not grown in sewage sludge-




 amended soil). EPA concluded that it is not appropriate to use those uptake  slopes to estimate




 risks from boron in crops grown in sewage sludge-amended soils (see Policy .Decision on page



 2).




      No other information is available on uptake slopes for boron.  Because Pathway 6 was




the  only 'critical pathway  for  boron and because this  pathway could not be evaluated using




available information after the detailed examination of the critical pathways, EPA concluded that




boron should not be on the list of pollutants for the Round Two regulation for land application.
                                          20

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 Fluoride




        Pathways 6 and 10 were critical for fluoride for both agricultural land and non-agricultural




 land (i.e., forest, reclamation sites,  and public  contact sites)  in the Comprehensive Hazard




 Identification study.  For Pathway 6 (animal foraging), "the. uptake slopes used in the analyses




 were obtained from non-sewage-sludge studies (i.e., crops from which the uptake slopes were




 obtained were not grown on sewage sludge-amended soils).  EPA concluded it is not appropriate




 to use those uptake slopes to estimate risks from fluoride in forage grown in sewage sludge-




 amended soils (see  Policy Decision on page 2).




       No other information is available on uptake slopes for fluoride.  Because Pathway 6 could




 not be evaluated using existing information after completion of the detailed examination of the




 critical pathways, EPA concluded that Pathway 6 is not critical.  For this reason, fluoride v/as not




 included on the  list of pollutants for the Round Two regulation for land application based on




 exposure through Pathway 6.




       Pathway  10 (predator of soil organism) also was critical for fluoride for agricultural land




 and non-agricultural land. The TRY for this pathway was based on a NOAEL of 10 mg/L in




 drinking water administered to mice (Kanisawa and  Schroeder, 1969). This was converted to a




 dietary equivalent value of 11 mg/kg-food using allometric equations (U.S. EPA, 1988).  Results




 of other studies indicate that a dietary equivalent value for fluoride of 52 mg/kg-food resulted in




 changes in teeth and liver, and structural and functional changes in the kidney (Jankauskas, 1974;




Lim  et al.,  1975; Roman et aL, 1977, as cited in IARC, 1982).




      The HEI  for Pathway  10 is the predator of a soil organism (e.g.,  a shrew). The effect




from the exposure in Pathway 10 is mild systemic  changes (e.g.,  changes in teeth and liver).
                                          21

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  Population effects from this exposure are unknown.

        Because the effect for which the TRY is protective is mild systemic changes and not

  population effects, and because there is some evidence that fluoride is necessary for fertility in

  mice (Messer et al. 1973, as cited in IARC, 1982), EPA concluded that the TRV used in the

  Comprehensive Hazard Identification study was not appropriate.  For this reason, and because no

  other relevant toxicological information on small mammals was available for Pathway 10, EPA

  concluded that Pathway 10 could not be evaluated for fluoride.  Thus, Pathway 10 is not critical

  for fluoride.

        The above information indicates that the critical pathways from the Comprehensive Hazard

 Identification study should not be the basis for including fluoride on the Round Two list of

 pollutants.  For this reason, fluoride was not placed on the list of pollutants for the Round Two

 sewage sludge regulation for land application.                                           -



 Manganese                                                .

       Pathways 3, 6, 7, and 14 were critical for manganese for agricultural land.  Pathways 3,

 4, 6, 7, 10, and 14 were critical for manganese for non-agricultural land.

       Pathway 3 is the child ingestion pathway. For agricultural land and public contact sites,

 a child between the ages of 1  and 6  is assumed to ingest 0.2 gram of sewage sludge (not the

 sewage sludge-soil mixture) daily. For forest and reclamation sites, a child between the ages of

 4 and 6 is assumed to ingest 0.2 grams of sewage sludge daily.

       The Reference Dose (RfD) for the Pathway  3 analyses  in the Comprehensive Hazard

Identification study was 0.005 milligrams of manganese per kilogram of body weight per day.
                                               j
                                          22

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  On May 1, 1996, the RfD for manganese in EPA's Integrated Risk Information System (IRIS)




  was changed.  The current RfD for manganese in IRIS is 0.14 milligrams of manganese per




  kilogram of body  weight per day for dietary exposure.  As indicated in the Uncertainty and




  Modifying Factors section in IRIS, when assessing  exposure to manganese  from  food, a




  modifying factor of one is used. When assessing exposure to manganese from drinking water




  or soil, a modifying factor of three is used. Because the HEI ingests sewage sludge, which is




  similar to soil, an uncertainty factor of three was applied to the RfD.  The RfD for the Pathway




  3 analyses should be 0.14 divided by 3, resulting in 0.05 milligrams of manganese per kilogram



 of body weight per day.




        Using the current RfD for manganese, the RfD ratio for Pathway 3 is 0.4 for agricultural




 land and public contact sites, and 0.3 for forest and reclamation sites.  Because these values are




 less than one, Pathway 3 is not critical for manganese.  For this reason, EPA concluded that




 manganese should not be on the list of pollutants for the Round Two  sewage sludge regulation



 based on exposure through Pathway 3.




        The uptake slopes in Pathway 4, which was criticaTfor forest and reclamation sites, were




 obtained using non-sewage-sludge studies (i.e., crops from which the uptake slopes were obtained




 were not grown in sewage sludge-amended soils). EPA concluded that it is not appropriate to




 use those uptake slopes for crops grown in sewage sludge-amended soils (see Policy Decision on




 page 2). Because there is no other information on manganese uptake slopes, manganese was not




 included on the Round Two list of pollutants based on exposure through Pathway 4.




       Pathway 6 also was critical for manganese for agricultural land, forests, reclamation sites,




and public contact sites.  EPA concluded that manganese should not be included on the  Round
                                          23

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  Two list of pollutants based on exposure through this pathway because the uptake slopes used in

  the analyses were obtained from non-sewage-sludge studies.  It is not appropriate to use those

  uptake slopes for crops grown in sewage sludge-amended soils (see Policy Decision on page 2).
                    *. .                                            •
        The TRVs for Pathway 7, which was critical for manganese for agricultural land, forest,

  and reclamation sites, and for Pathway 10, which was critical for forest and public contact sites,

  are based on the results of studies using laboratory animals (i.e., rats).  After reviewing the results

  in the original study (Laskey et al., 1982) used to develop the TRY, an error was found in the

 dietary value.   The dietary  value  used to develop the  TRY in the Comprehensive  Hazard

 Identification study was 170 mg/kg-food. This value was divided by 10 to determine the TRY.

       The dietary value in the Laskey study was 350 mg/kg-food. Thus, the TRY should have

 been 35 mg/kg-food instead of 17 mg/kg-food.  When the revised TRY was used to calculate the

 RQs. for Pathways 7 and 10, the RQ for Pathway 7 was 0.7 and the RQ for Pathway 10 was just

 1.  Therefore EPA concluded that manganese should not be included on the Round Two list of

 pollutants, because the RQ became less than one for one pathway,  and just met the level of

 concern for the other pathway.

       The final pathway that was critical for manganese is  Pathway 14 (i,e., ground water).

 This  pathway was  critical  for  both agricultural land and non-agricultural  land (i.e.,  forest,

 reclamation sites, and public contact sites).

       Two of the important variables for^this pathway are soil type and partition coefficient.

As mentioned previously, EPA  concluded that assuming a  soil type of either sandy loam,

shrinking clay, or sand is conservative. During the detailed examination of the critical pathways,

the assumed soil type for Pathway 14 for manganese was sandy loam, not sand.
                                          24

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        The partition coefficient for sandy loam with a porewater pH of 8 ranges from 8418 liter




 per kilogram to 15,774 liter per kilogram (Gerritse et al., 1982). Using any partition coefficient




 within that range is conservative.  For the Pathway 14 analysis for manganese,  when a value in




 the middle of the above range is used, Pathway  14 is not critical for manganese.




        The above information indicates that after completion of the detailed examination of the




 critical pathways for manganese from the Comprehensive Hazard Identification study, none of




 the pathways are considered to be critical for agricultural land and non-agricultural land.  For this




 reason, manganese was not included on the final list of pollutants for the Round Two sewage




 sludge regulation for land application.,








 Thallium




       The critical pathway for thallium for agricultural land, forest, reclamation sites, and public




 contact sites  was Pathway 3 - child ingestion of sewage sludge. In the Comprehensive Hazard




 Identification study, the ratio of exposure from Pathway 3 to the RfD for thallium was two.




       The thallium RfD is based  on the results of a 90-day study during which rats ingested




 soluble thallium salts in drinking water (IRIS, 1996). The uncertainty factor in the RfD is 3,000.




 In the case of the Pathway 3 analysis, the margin of safety is 1,500 (i.e., 3,000. divided by an



 RfD ratio of 2).       •     '




       The absorption of metals like thallium in sewage sludge in the gastrointestinal tract, after




the sewage sludge is ingested by a child is expected to be lower than the absorption of soluble




salts of thallium. For this reason and because  the margin of safety for the Pathway 3 analysis




is 1,5.00, EPA concluded that Pathway 3 was not critical for thallium.  Thus, thallium was not
                                          25

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   included on the final list of Round Two pollutants' for land application for either agricultural land

   or non-agricultural land.
                                                                          *

   Tin

         The critical pathway for tin for agricultural land,  forest, and public contact sites was

  Pathway 7 (i.e., grazing animal that ingests sewage sludge directly).  The TRY for tin was based

  on the results of a study in which female rats were fed 5 ppm tin hi drinking water (Schroeder

  et.al., 1968b).  The observed effect in this study was decreased longevity.

        The LOAEL reported in ATSDR (1992b) was 0.7 mg/kg/day, which is equivalent to a

  dietary value of 9 mg/kg-food.  This value was divided by 10 to obtain a TRY for Pathway 7 of

  0.9 mg/kg-food.  When reviewing  the original study on which  the TRY is based, an error was

  found. The TRY should be 0.45 mg/kg-food, which means the  RQ for tin for agricultural land,

  forest, and reclamation sites should have been four instead of two.

    '    Studies other than the Schroeder et al. study (1968b) failed to find any effects in mice

  administered 5 ppm  tin in  drinking water (Schroeder and  Balassa,  1967).  In addition, other

  studies examining systemic effects  in rats and mice found NOAELs  an order of magnitude or

• more higher than the LOAEL from the Schroeder et al. study (1968b). Effects observed in these

 studies are not clear with respect to population effects from exposure to tin.

        Because the LOAEL used to calculate the TRY for tin is from a study in which rats were

 administered tin  in drinking water (absorption of tin in food or sewage- sludge is likely to be

 lower than absorption of tin in drinking water); because results of other studies indicate that the

 NOAEL for tin is higher than the LOAEL from the Schroeder et al. study (1968b); and because
                                           26

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 the population effects from exposure to tin are not known, EPA concluded that the TRY from




 the rat study should not be used as the TRY for the HEI hi Pathway 7.




       Because there is no other more appropriate information on the TRY for tin, Pathway 7




 could not be evaluated for tin after completion of the  detailed examination of the critical




 pathways. For this reason, Pathway 7 is not critical for tin, and tin was not included on the




 Round Two list of pollutants based on exposure through Pathway 7.








 Titanium




       The critical pathway for titanium for agricultural land arid reclamation sites was Pathway




 6 (i.e., animal foraging on sewage sludge-amended soils). The uptake slopes used in the Pathway




 6 analyses were obtained from non-sewage-sludge studies (i.e., crops from which the uptake




 slopes were obtained were not grown in sewage sludge-amended soils).  EPA concluded that it




 is not appropriate to use uptake slopes from non-sewage-sludge  studies  for forage  grown in




 sewage sludge-amended soils (see Policy  Decision on page 2).                          -




       No other information is available on uptake slopes for titanium.  Because Pathway 6 could




not be evaluated using available information, EPA  concluded that Pathway 6 is not critical and




that titanium should not be on the list of pollutants for the Round Two sewage sludge regulation




for land application based on exposure through Pathway 6.
                                         27

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    2.3.2 Surface Disposal




    Antimony and Barium




          The critical pathway for antimony and barium for surface disposal is the groundwater




    pathway. As mentioned in the above discussion of antimony for land application, one way to




    evaluate the RfD ratio (i.e., four for antimony and one for barium) for this pathway is to consider




    the uncertainty  factor for the RfD with respect to the RfD ratio and the effect for which the RfD



    is protective.                                     ,




          The antimony and barium RfDs are based on an uncertainty factor of 1000.  The margin




    of safety for a surface disposal site (i.e., surface impoundment) would be 250 (i.e., 1000 divided.




    by 4) for antimony and 1000 (i.e.,  1000 divided by one) for barium. EPA concluded that for




    antimony a margin of safety of 250 is sufficiently protective for the HEI (i.e^, human) in this case"




    because the effect upon which the RfD is based (i.e.,  changes in cholesterol and glucose blood




    levels) is not severe and is likely reversible. EPA also concluded that barium just met the critical




   pathway criteria. For these reasons, EPA concluded after completion of the detailed examination




   of the critical pathways that antimony and barium should not be on the Round Two list  of




   pollutants for surface disposal based on exposure through the groundwater pathway.








   Beryllium and Manganese                                         i




         The groundwater pathway also was the critical pathway for beryllium and manganese for




,   surface disposal.  As mentioned previously during the discussion of the groundwater pathway for




   land application, two important parameters for the groundwater pathway are soil type and soil-



   water partition coefficient.                                                      .
                                            28

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        During the Comprehensive Hazard Identification  study, the soil type for all  surface




  disposal sites was assumed to be sand.  EPA concluded that using a soil type of eithe:r sandy



  loam, shrinking clay, or sand is conservative.




        A soil-water partition coefficient for sandy soil with a porewater pH of 5 was used in the




  Comprehensive Hazard Identification study for surface disposal. However, if the median partition




  coefficient for sandy loam with a porewater pH of 8 is used in the analysis, the groundwater




  pathway is no longer critical for  beryllium and manganese for. surface disposal.




        EPA concluded that it is reasonable to use the sandy loam soil type in the surface disposal




 groundwater analysis.  It is also reasonable to use the median value for partition coefficient in




 the range of partition coefficients for sandy loam soil in the analysis.  When this value is used,




 the groundwater pathway is not critical for beryllium and manganese for surface disposal. For




 this reason, EPA concluded that those pollutants should not be on the, final list of pollutants for




 the Round  Two regulation for surface disposal based on  exposure through the groundwater



 pathway.                                                      •








 2.3.3  Incineration




       Results of the Comprehensive Hazard Identification study indicate that no pollutants




warrant consideration for the "list of pollutants  for the Part 503 Round Two  regulation for




incineration.  Dioxins/furans will be re-evaluated for the Part 503  use  or disposal practices,




including  incineration, at the completion of EPA's dioxin reassessment.
                                           29

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  2.4    POLLUTANTS RECOMMENDED BY OTHERS FOR THE ROUND TWO LIST
         OF POLLUTANTS


         Prior to conducting the Comprehensive Hazard Identification study for the 31 candidate

  pollutants for the Round Two list of pollutants, EPA programs and experts from outside of EPA

  were contacted to obtain data (e.g., plant and animal uptake data) on the 31 candidate pollutants.

  Comments were received from Dr. George O'Connor from the University of Florida and Dr.

  Rufus Chaney from the U. S. Department of Agriculture (see Appendix D3).

        Dr. O'Connor provided references on plant bioavailability for some of the candidate

  organic pollutants. Information from those references was used in the Comprehensive Hazard
                             \                       •
  Identification study, where applicable.                                         •

        Dr.  Chaney  also provided information  on several of  the candidate pollutants.  He

 recommended that beryllium, boron, dioxins/furans, coplanar polychlorinated biphenyls, cobalt,

 fluoride, and iron be on the Round Two list of pollutants for land application.

        With the exception of cobalt and iron, the pollutants that Dr. Chaney recommended for

 the  Round Two list of pollutants for land application were evaluated in the  Comprehensive

 Hazard Identification study. The results of the detailed examination of the critical pathways.for

 those pollutants are presented in other sections of the Technical Support Document (U.S. EPA,

 1996).


       Both cobalt and iron were evaluated for the list of pollutants for the Part 503 Round One

regulation for land application.   Neither pollutant was include  on the  Round  One list of

pollutants.


       Cobalt was not included on the Round One list of pollutants because the hazard index

(estimated exposure divided by the reference dose) was less than one.  Dr. Chaney stated that '


                                         30

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 results of cobalt feeding trials indicate that a cobalt concentration between 5 and .10 milligrams




 per gram of diet may be injurious to sheep and cattle.  Cobalt was detected in nine percent of the




 samples from the National Sewage Sludge Survey.  Using the 98th percentile concentration for




 cobalt from the NSSS (i.e., 104 mg/kg with non-detected values set equal to the minimum level)




 and the fraction of the  animal's  diet that is  sewage sludge  used  in  the Round One  risk




 assessments (i.e., 1.5 percent), the 5-10 milligram per kilogram diet concentration for cobalt is




 not expected to be reached in an animal's diet from ingestion of sewage sludge.  In addition,




 none of the updated information submitted by Dr. Chancy suggests that the original hazard index




 for cobalt would change.  For these reasons,  EPA concluded that cobalt should not be on the list




 of pollutants for the Part 503 Round Two regulation for land application.




       Iron was not included on the Round One list of pollutants even though the hazard index




 for grazing  animals that ingest the sewage sludge/soil mixture (i.e., Pathway 7) was 2.1. TKe




 rationale for not including iron on the Round One list was that the gracing  animal  index was




 based  on a  worst worst-case sewage sludge iron concentration and the  assumption that five




 percent of  the  animal's  diet is Sewage sludge.   If sewage  sludge with  a  "typical" iron




 concentration (i.e., 28,000 mg/kg (U.S. EPA, 1985)) is used in the analysis, the hazard index for




 grazing animals is less than one.  The hazard index for iron also is expected to be less man one




 if the fraction of the animal's diet from the risk assessment for the Round One regulation (i.e.,




 1.5 percent) and the 90th percentile concentration for iron from the NSSS (i.e., 41,800 mg/kg)




are used to develop the index. For these reasons, EPA concluded that iron should not be on the




list of pollutants for the Part 503 Round Two regulation for land application.
                                          31

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     3. LIST OF  POLLUTANTS FOR THE ROUND TWO
                  SEWAGE SLUDGE  REGULATION

        On November 30, 1995, EPA submitted the list of pollutants for the Round Two sewage
 sludge regulation to the District Court in Oregon.  The court notice is presented hi Appendix D2.
       After considering information from the Comprehensive Hazard Identification study; the
 rationales for deleting inorganic pollutants from the list of pollutants that warranted further
 consideration; and information received from others, EPA concluded that two pollutants should
 be on the list for each  use or disposal practice.  They are: dioxins/furans (all monochloro to
 octachloro congeners) and polychlorinated biphenyls (coplanar). The court notice indicates that
 EPA may, in the exercise of its discretion, determine to add or delete other pollutants to or from
 this list at the time the Round Two regulation is proposed.
       In addition to the list of pollutants submitted  to the court, EPA may change  a limit for
 the pollutants in the Round One regulation during development of the Round  Two regulation.
 For  this reason, the Round One pollutants also are considered pollutants for the Round  Two
 sewage sludge regulation.                                      .                      :
       Including the pollutants from  the Round One regulation, the list of pollutants for the
Round Two sewage sludge regulation by use or disposal practice is:
Land application
       arsenic,  cadmium, copper,  lead,  mercury,  molybdenum,  nickel,  selenium,  zinc,
      dioxins/furans, and coplanar polychlorinated biphenyls.
                                         32

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 Surface disposal

        arsenic, chromium, nickel, dioxins/furans, and coplanar polychlorinated biphenyls


 Sewage sludge incineration

        arsenic, beryllium, cadmium, chromium, lead, mercury, nickel, total hydrocarbons (or

        carbon monoxide), dioxins/furans, and coplanar polychlorinated biphenyls
                          •               T

        Dioxins/furans were included on the list of pollutants for sewage sludge incineration even

 though results of the screening risk assessments indicate that no pollutant warrants consideration

 for the Round Two list of pollutants for incineration. EPA currently is conducting a reassessment

of dioxins/furans.   Because the results of this  assessment are unknown, dioxins/furans were

included on the Round Two list of pollutants for all use or disposal practices. At the completion

of the dioxin reassessment, EPA may decide not to regulate dioxins/furans for a particular .use

or disposal practice or may decide to regulate dioxins/furans on an accelerated schedule.
                                           33

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                              4. REFERENCES


 Agency for Toxic Substances and Disease Registry.  1992a.  lexicological Profile for Barium
        and Compounds. Prepared by Clement International Corporation under contract no. 205-
        88-0608.  U:S. Public Health Service. ATSDR/TP-91/03.

 Agency for Toxic Substances and Disease Registry. 1992b. Toxicological Profile for Tin and
        Compounds.  Prepared by  Life Systems under  subcontract to Clement International
        Corporation under contract no. 205-88-0608. U.S. Public Health Service.  ATSDR/TP-
        91/27.

 Corey,  R.B., L.D. King, C. Lue-Hing, D.S. Fanning, J.J. Street, and J.M. Walker.  1987. Effects
        of Sludge Properties on Accumulation of Trace Elements by Crops. In: Land Application
        of Sludge.  A.L. Page, T.J. Logan, and J.A. Ryan.  Lewis Publishers, Inc. Chelsea, MI.

 Gerritse, R.G., R.  Vriesema, J.W. Dalenberg, and H.P. De Roos. 1982. Effect of Sewage Sludge
       on Trace Element Mobility in Soils. Journal of Environmental Quality.  ll(3):359-364.

 IARC (International  Agency for Research on Cancer).    1982.  IARC Monographs on the
       Evaluation of the Carcinogenic Risk of Chemicals  to Humans.  Some Aromatic Amines,
       Anthraquinones and Nitroso Compounds, and Inorganic Fluorides Used in Drinking-water
       and Dental Preparations.  Vol. 27.

 IRIS.  1996.  Integrated Risk Information System.  June.

 Jankauskas, J. 1974.  Effects of Fluoride on the Kidney (A Review). Fluoride.  7-93-105  [As
       cited in IARC, 1982].

 Kanisawa, M. and H.A. Schroeder.  1969.  Life Term Studies on the Effect of Trace Elements
       on  Spontaneous Tumors in Mice and Rats.  Cancer Res.  29:892-895.

 Laskey^ J.W., G.L. Rehnberg, J.F. Hein, and S.D. Carter.  1982.  Effects of Chronic Manganese
       (Mn3O4) Exposure on Selected Reproductive Parameters in Rats.  J. Toxicol. Environ
       Health. 9:677-687.

 Lim. J.K.J., G.K.  Jensen, and O.K. King, Jr. 1975.  Some Toxicological Aspects of Stannous
      Fluoride After Ingestion as  a Clear, Precipitate Free Solution Compared to Sodium
      Fluoride. J. Dent. Res.  54:615-625.  [As cited in I ARC,  1982].

Messer,  H.H., W.D.  Armstrong, and L.  Singer.   1973., Influence  of Fluoride Intake on
      Reproduction hi Mice.  J. Nutr. 103:1319-1327. [As cited in IARC, 1982].

Perry, H.M., Jr., SJ.  Kopp, M.W. Erlanger, and E.F. Perry. 1983. Cardiovascular Effects of


                           '34

-------
        Chronic Barium Ingestion. Trace Subst. Environ. Health.  17:155-164.

  Perry, H.M.,  Jr.,  E.F.  Perry,  M.W. Erlanger, .and SJ.  Kopp.   1985.   Barium-Induced
        Hypertension.  In: Advances in Modern Environmental Toxicology, Vol. IX, Inorganics
        in Drinking Water and Cardiovascular Disease.  EJ. Calabrese, R.W. TuthilL, and L.
        Condie, eds. Princeton Scientific Publishing Co., Inc. Princeton, N.J. pp. 221-229.

  Perry, H.M., Jr., SJ. Kopp, E.F. Perry, and M.W. Erlanger. 1989. Hypertension and Associated
        Cardiovascular Abnormalities Induced by Chronic Barium Feeding. J. Toxicol Environ
        Health.  28:373-388.

  Roman, R.J., J.R. Carter, W.C. North, and M.L. Kauker. 1977. Renal Tubular Site of Action
        of Fluoride in Fischer 344 Rats. Anesthesiology. 46:260-264. [As cited in I ARC, 1982].

  Schroeder, H.A. and J.J. Balassa.  1967.  Arsenic, Germanium, Tin and Vanadium in Mice:
     .   Effects on Growth, Survival and Tissue Levels. J. Nutr. 92:245-252.

 Schroeder, H.A., M. Mitchener, J.J. Balassa, M. Kanisawa, and A.P. Nason.  1968a.  Zirconium,
        Niobium, Antimony and Fluorine in Mice: Effects on Growth, Survival'and Tissue Levels'
       'J. Nutr.  95:95-101.                                           -

 Schroeder, H.A., M. Kanisawa, D.V. Frost, and M. Mitchener.  1968b.  Germanium, Tin and
       Arsenic in Rats: Effects on Growth, Survival,  Pathological Lesions and Life Span  J
       Nutr.  96:37-45.

 Schroeder, H.A., M. Mitchener, and A.P.  Nason.  1970.   Zirconium, Niobium, Antimony,
       Vanadium and Lead in,Rats: Life Term Studies.  J. Nutr.  100:59-68.

 Schroeder, H.A. and M. Mitchener. 1975.  Life-term Effects of Mercury, Methyl Mercury, and
       Nine Other Trace Metals on Mice. J. Nutr.  105:452-458.

•Smyth, H.F., Jr. and W.L. Thompson,.   1945.  The  Single Dose  and Subacute-Toxiciry of
       Antimony Oxide (Sb2O3). Melon Institute of Industrial Research, University of Pittsburgh
       OTS 206062. [As cited in ATSDR, 1992bj.

Sunagawa, S. 1981. Experimental Studies on Antimony Poisoning. Igaku kenkyu  51-129-142
       [As cited in ATSDR, 1992b].

U.S. EPA. 1985.  Environmental Profiles and Hazard Indices for Constituents of Municipal
       Sludge: iron.  Office of Water, Regulations and Standards. June.

U.S. EPA. 4988:. Recommendations for and Documentation of Biological Values for Use in
    .   Risk Assessment. Environmental Criteria and Assessment Office, Office of Health and
       Environmental Assessment, Office  of Research  and Development.   EPA/600/6-87/008.

                                         35

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       February.        .                                                           •

U.S. EPA.   1992.  Technical Support Document for Land Application of Sewage Sludge.
       Appendix J.  Office of Water, Office of Science and Technology. EPA 822/R-93-001a.
       November.

U.S. EPA.  1996. Technical Support Document for the Round Two Sewage Sludge Pollutants.
       Health and Ecological  Criteria Division, Office of Science and Technology  Office of
       Water. EPA-822-R-96-003.  August.
                                       36

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                APPENDIX Dl

 LIST OF 31 CANDIDATE POLLUTANTS FOR THE
  ROUND TWO SEWAGE SLUDGE REGULATION
SUBMITTED TO THE DISTRICT COURT IN OREGON

-------

-------
   v   .         IN THE UNITED STATES DISTRICT COURT
                     FOR THE DISTRICT 0? OREGON

 FRANK GEARHART,, CITIZENS  INTERESTED      )'   "'" -V ": ^T
 IN BULL. RUN,  INC.,  An Oregon             )
 Corporation,  KATHY  WILLIAMS, AND         )•    ;      '  ..
 PRANCES PRICE COOK,                      (•:.••'-.
                                          I     '•'••. :i

           Plaintiffs,                    )       	  '

 NATURAL RESOURCES DEFENSE COUNCIL,       )

           Intervenor Plaintiffs,         )

 ASSOCIATION OF METROPOLITAN SEWERAGE     I  ClVl1 Np«  89-fi266-HO
 AGENCIES,                                j

           Intervenor Plaintiffs,         )
           v.
 CAROL M. BROWNER                        ]
 Administrator, United States            \
 Environmental Protection Agency,        )

           Defendant.                    j        •    .



                       NOTICE OF POLLUTANTS

      Pursuant to paragraph 2. of the Consent Decree entered in this

proceeding on  September  5,  1990,  as  modified  by  this  Court's

September 14,  1993 order, the U.S.  Environmental Protection Agency

 ("EPA")  hereby gives notice that,  based on available  information

reviewed to date, EPA presently  intends to propose for  regulation

under section  4OS(d)<2J{B)(i) of the Clean Water  Act, 33  U.S.C.  §

1345(d)(2)(B)(i), the following pollutants:1

     Acetic  acid (2,  4,  -dichlorophenoxy),  aluminum,  antimony,

asbestos, barium, beryllium, boron, butanone  (2-), carbon
            ^?  information available at the time of proposal, EPA
     «  +   discretion to either add or delete pollutant^ from the
     of those that it currently intends to propose for regulation^

-------
                         cyanides
               fluoride,.
                                   phenol.

                              biphenyls


                       ,  tin,  titani™, tolu«n«,

tarichlorophenoxyacetic iciii fa   4   s-\
                             C2'  4'  5 }'
acid (C2 -  C2/4/ Sr)J/
                                                      ^

                                                      o          '
                              Respectfully
                                    E. FLINT
                              Acting Assistant Attorney General

                                v
                                    —r—*- »*«vitt. of Justice
                             „  :-.- Pennsylvania Ave.,  N.W
                             Washington,  O.c.   20530
                             (202)  S14-3785


                              /v,
                             RJCHARO T. WITT, Attorney	

                              ri0             Counsel  (LE-132W1
                             401 M Street, s.W.

                             Washington, D.C.  20460
                             (202)   260-7715

-------
                               JACK C.  WONG - Bar No.  67138
                               United States Attorney
                                      RAY  - Bar HO.  72319~~
                                   itant United States Attorney
                               District of  Oregon
                               701 High Street .
                               Eugene, Oregon  97401
                               (503) 465-6771
OF COUNSEL:

GERALD H. .YAKADA
Acting General  Counsel

DAVID M. GRAVALLESE
Assistant General Counsel
U.S. Environmental Protection Agency

Dated:  May 21,  IS93

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                APPENDIX D2
     FINAL LIST OF POLLUTANTS FOR THE
   ROUND TWO SEWAGE SLUDGE REGULATION
SUBMITTED TO THE DISTRICT COURT IN OREGON

-------

-------
 LOIS J. SCHIFFER
 Assistant Attorney General
 Environment and Natural Resources
      Division

 MARK A. NITCZYNSKI, Attorney
 Environment and Natural Resources
      Division

 RICHARD T. WITT, Attorney
 Office of General Counsel (LE-132W)
 U.S. Environmental Protection Agency

 JACK C. WONG - Bar No. 67138
 United States Attorney.

 JOHN C. RAY - Bar No. 72319
 Assistant United States Attorney
 District of Oregon
 701 High Street
 Eugene, Oregon  97401             ~
 (503)  465-6771
                                               95HQV29
                                               • ERK. U.S. DISTRICT COURT
                                                 DISTRICT OF OREGON
                                                  EUGENE. OREGON
               IN THE UNITED STATES DISTRICT COURT
                    FOR THE DISTRICT OP OREGON
FRANK GEARHART, CITIZENS INTERESTED
IN  BULL RUN,  INC., An Oregon
Corporation,  KATHY WILLIAMS, AND
FRANCES PRICE COOK,

           Plaintiffs,

NATURAL RESOURCES DEFENSE COUNCIL,
INC.,

           Intervenor Plaintiffs,

ASSOCIATION OF METROPOLITAN SEWERAGE
AGENCIES,                •   ,

           Intervenor Plaintiffs,

           v.

CAROL M. BROWNER
Administrator,  united States
Environmental  Protection Agency,

           Defendant.
                                             Civil No.  89-6266-HO
                                             REVISED NOTICE OF
                                             POLLUTANTS
Revised Notice of Pollutants -

-------

-------
      On May 24,  1993, pursuant to Paragraph 2 of the Consent
 Decree entered in -this proceeding on September 5,  19 9O,  as
 subsequently.modified by this Court's orders, the U.s.
 Environmental Protection Agency ("EPA")  submitted a Notice of
 Pollutants ("Notice").  The Notice stated that the Agency was
 considering proposing 31 pollutants for  regulation under section
 405(d)(2)(B)(i)  of the Clean Water Act,  33 U.S.C.  §
 1345(d) (2) (B) (i)'v  Paragraph 9d of the Consent Decree provides
 that the Agency  may revise this list of  pollutants if it
 concludes  that regulations are not needed for some or all -of the
 31 pollutants.   Based on current information,  EPA  has concluded
 that 29  of the listed pollutants need not be  regulatedj
 acetic acid (2,  4,  -dichlorophenoxy),  aluminum,  antimony,
 asbestos,  barium,  beryllium,  boron,  butanone  (2-),  carbon
 disulfide,  cresol  (p-),  cyanides (soluble salts and complexes),
 endsulfan-II,  fluoride,  manganese, methylene  chloride, nitrate,
 nitrite, pentachloronitrobenzene,  phenol,  phthalate (bis-2-
 ethylhexyi), propanone (2-),  silver, thallium,  tin,  titanium,
 toluene, trichlorophenoxyacetic  acid  (2,  4, 5-),
 trichlorophenoxypropionic acid  ([2 -  (2,4, 5-)], and vanadium.
     Thus,  EPA has  concluded  that  only two of the  listed
pollutants  warrant  further consideration  for regulation:
dioxins/dibenaofurans  (all monochloro to  octochloro  congeners)
and polychlorinated biphenyls  (co-planar).  EPA may,  in the
exercise of its discretion, determine to  add or dele-te other
pollutants  from this list at the time of proposal.
Revised Notice of Pollutants  - 2

-------

-------
Dated:   November 28,  1995
                                Respectfully submitted,

                                LOIS J.  SCHIFPER
                                Assistant Attorney General
                                Environment and Natural Resources
                                     Division
                                MARK A. NITCZYkSKI,  Attorney
                                Environment and Natural Resources
                                    . Division
                                U.S. Department of Justice
                                10th & Pennsylvania  Ave. ,  N,w.
                                Washington/ D.C.  20530
                                (202) 514-3785
\
J~
                               RICHARD T. WITT, Attorney
                               Office of General Counsel  (LE-132W)
                               U.S. Environmental Protection
                               Agency
                               401 M Street, S.W.
                               Washington, D.C.  20460
                               (202)  260-7715

                               JACK C. WONG - Bar No. 6713 S
                               United States Attorney

                               JOHN C, RAY - Bar No. 72319
                               Assistant United States Attorney
                               District of Oregon
                               701 High Street
                               Eugene,  Oregon  97401
                               (503)  465-6771
Revised Notice of Pollutants - 3

-------

-------
                      CERTIFICATE OP SERVICE

     1 hereby certify that pn this November 28,  19? 5 I caused a
copy of the foregoing Revised Notice of Pollutants to be served
by first class mail, postage prepaid,  on the following counsel:

WILLIAM CARPENTER
474 Willamette
Suite 303
Eugene, OR  97401

     Counsel for Plaintiffs

JESSICA IANDMAN           •       .
Natural Resources Defense Council,  Inc.
1350 New York Ave. , N.W.
Suite 300
Washington , DC .20005

     Counsel for Natural Resources Defense Council, Inc.  -

LEE WHITE       '
122S I Street, N.W. , Suite 300
Washington, DC 20005

     counsel for Association of Metropolitan Sewerage Agencies
                                                &
                                        Annette Bucco

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               APPENDIX D3

     RESPONSES TO REQUESTS FOR DATA
ON THE ROUND TWO CANDIDATE POLLUTANTS

-------

-------
       United Sratej
       Department of
       Aoricuiture
Agricultural.
Raeaarch
Seivica
Beitsviiie Area
Baftsvilfa. Agricultural
Rasiarch Canter
BeltSvUla. Maryland
20705
 May 10, 1995

 SUBJECT:  Round 2 contaminants.

       TO:  Alan B. Hals, Chief, Multimedia Risk Assessment Branch.
            Yogi Pstel, Multimedia Risk Assessment Branch.

    FROM:  R.L. Chaney, USDA-ARS, Environmental Chemistry Lab,

 I am responding to your letter of April 18, 1995 requesting information on
 plant uptake of these compounds or metals. 1 have written about the risks of
 most of these metals, and some of the organics over the last 10 years. I
 have huge amounts of literature on these elements, and several you appear
 to left our of consideration. Where uptake by plants is known to occur to
 any significant level from sludge-amended soils, these lesser-studied
 elements have often been examined  by pot and field studies  of Dr. Don Usk
 and his collaborator* (including me);  they examined the Sludges, soils, plants,
 and animal tissues using neutron activation (and atomic absorption or ICP) to
 analyze over 40 elements in numerous experiments.

 I would hope that demonstrated Iron toxlclty to  cattle and horses from high
 Fe sludges would put Fe on the list.  Similarly, Co is a significant possibility
 based on food-chain Injury to cattle and sheep.  Fluoride Is also a
 demonstrated risk from sludges, although mostly in the livestock grazing on
 surface-applied sludges. 1 fiad brought up these omissions in Round  1, so I
 am a little surprised that Fe and Co were not on the list. Even more
 surprised when Tl, Sn, and some of the others on  your preliminary list were
 being considered when  papers I have given EPA clearly show the lack of risk
 under any route of exposure to sludges.  It would seem to me that your list
 partially came from the  Water people, and they base their concern on toxlclty
 of water soluble salts in distilled water, or even  on injected water soluble
 salts (e.g., Ag, TI, Sn. etc.).

 If there is a message to this letter, it  is my concern about the need to have
iron  and cobalt on the thorough evaluation list.  Comments below will
 provide a summary of the literature related to Pathway Analysis of Risk, and
useful references.
If you want to reach me regarding these comments on the Round 2 List of
Contaminants, I will bo at my lab (301-504-8324) May 10 and 11, leaving

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 for England In mid-afternoon.  I will return the evening "of May 18, and be in
 the iab on May 19.

 Aluminum:  AI is severely phytotoxic to plants when soils remain at pH lower
     than about 5.2 for a number of years. Clays dissolve and AJ3+ enters the
     cation exchange complex in soil.  The water soluble AI3+ injures root
     Initials, reduces root grown and reduces yield. Toxic AI in subsoils
     prevents plants from  using water stored in subsoils. AI phytotoxicity Is a
     common problem on agricultural and forest land. Addition of inorganic AI
     salts would allow development of AI phytotoxiclty soon  after acidification
     since precipitated AI(OH)3 !s present when the soil pH is over 5.2-5.5.

     Little AI Is absorbed and translocated  into plant shoots, and even less
     into fruits and grains. Most plant AI is soil contamination from "wind-
     blown dust in the field.  Soil AI has lower bioavailability than do soluble
     salts of AI. Other than phytotoxicity, we know of no Pathway in which
     sludge-borne AJ in soils will cause risk compared to unsludged soils. AI
     should be deleted from the list.

 Antimony:  In the 1970s and 1980s. Dr. Lisk and his collaborators used
    neutral activation to measure many elements in plants, sludges, and
    soils.. In pot and field experiments.  There were some limitations in these
    studies.  However, the results with antimony were useful to your need.
    The normal chemical form of antimony (Sb3*) in soils is quite Insoluble at
    normal soil pH levels.  Plant leaves, fruits, or grains had unchanged Sb
    concentration even when soil Sb was  significantly increased by applied
    sludges; and animals did not accumulate Sb from sludge grown crops of
    Chaney et al. (1978).  Sb has little toxicity to animals or plants. It is
    used some medications. 1 believe Sb should be deleted from your list.

 Barium:  in normal soils, which have adequate amounts of Ca and Mg even
    when sludges are utilized on land, Ba is an exchangeable cation which is
    pretty insoluble when  sulfate is at the  levels in  soil required to produce
    high yielding crops. Plant shoots have little response to added sludge
    Ba, again from the data of Lisk et al. (including  the Chaney et al., 1978b)
    paper on chard fed to  Guinea pigs) show no risk of injury or residue
    transfer to livestock or wildlife.  Barium occurs  at unusual levels in a few
    crop species, including Brazil nut, but Lisk and other researchers have
    not shown significant increase In crop Ba on sludge-amended soils.

Beryllium: Added to soils as a soluble salt. Be has low phytoavailability. Lisk
    found little evidence that sludge Be moved Into plants.  And no evidence
    that Be accumulated in, animal tissues when sludge grown crops were

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    fed to test animals.  Be may require full evaluation because of known
    possible uptake and important industrial toxicology information.
    However, only Lisk may have measured Be in sludge research studies,
    and I'm not sure even he did.  My comments are based on basic studies
    in which Be salts were added to soils for plant studies, and the NRC
    (1980) book on livestock.

 Boron: Boron is important in agriculture and the  environment because It is
    phytotoxlc. High water soluble B in soils is accumulated by most plants,
    and they suffer phytotoxlclty at foliar B levels which are not high enough
    to be toxic to livestock chronically fed the  crops suffering B toxicity.
    There Is reasonably good evidence that B is required by animals, and that
    dietary B is generally low. I can perceive no  risk except phytotoxlclty
    from sludge B; Lisk et al. provided good evidence of lack of B toxicity or
  .  food-chain accumulation of boron.

    Only a few studies of sludge or effluent use on cropland or forests has
    shown B phytotoxicity.  In one, a sensitive crop received spray-applied
    effluent with over 1 mg B/L. in a sludge study, a sensitive crop suffered
    B phytotoxicity when a sludge containing glass fiber wastes was land
    applied. Slow dissolution of B from the glass fibers caused excessive B
    uptake. More B tolerant crops would not have been expected to suffer
    any effects of biosoiids-applied B in that study. I summarized sludge and
    compost B data in the Chaney and Ryan (1993) paper from the Ohio
    Composting Conference (see at end of reference section). The
    appropriate analysis of sludge boron risk will  require extraction of "hot
    water soluble" boron.  Based on substantial animal tolerance of B {NRC,
    1980), only the phytotoxicity pathway will require risk assessment.

Fluoride: A few sludges contain very high levels  of F, resulting from
    computer chip manufacturing wastewaters {HF is  used to leach  Si from
  .  marked surfaces of the chip}, and from aluminum  smelting processes.
    One sludge containing about 5% F was  studied by Davis, 1980. Ha
    found this sludge could induce  F phytotoxicity in ryegrass from soil
    applied high-fluoride sludge.  Generally,  foliar exposure of plants to HF
    causes high accumulation of F in the plants, which In turn poisons
    livestock.  It is widely shown that animals are at much greater fluoride
    risk from sludge of soil ingestion than from plant uptake.

    In the Denver sludge feeding studies (Klenhoiz et al. and Baxter  et al.),
    CaF (the solid phase F compound in sludges)  could be dissolved in the
    digestive system of cattle, and it could cause bones to become brittle
    and teeth to break. Analysis of sludges, using some selected

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    concentration below which no harm is expected to plants or livestock,
    will provide the protection needed for humans, livestock, and wildlife.
    Only highly contaminated soils will have phytoavailabte F.

Manganese: Few sludges contain high levels of Mn (> 1500 ppmDW), In
    fact, the principle problem regarding sludges is the induction of Min
    deficiency when lime-treated sludges are used on coastal plain soils
    (historically depleted of total soil Mn, so they are more susceptible to '
    limo-induced-Mn deficiency}.  I reviewed Mn in the Chaney and Ryan
    (1993a) paper at the Ohio Composting Conference.

    We have been testing use of Mn amendments to sludges to prevent
    induced-Mn deficiency from lime-treated sludges, and have found no
    evidence of plant toxicity when  limed sludge was enriched In Mn by
    about 6,000 ppm.  Al Rubin heard our seminar on May 3 at the Maryland
    Department of the  Environment.                  .

    When high Mn soils are strongly acidified (pH £ 5.4),  Mn24 accumulates
    among the exchangeable cations, and can cause phytotoxicity to
    sensitive crops.  However, except for rare Mn hyperaccumulator species,
    plants suffer phytotoxicity and leaves remain low in  Mn such that they
    do not comprise chronic toxicity risk to  livestock or wildlife.  Farmers are
    forced to add limestone to raise soil pH  to prevent Mn phytotoxicity in
    strongly acidic high Mn soils.  I believe that the added risk from
    sludge-borne Mn is trivial.

Silver: Silver is toxic to animals when injected, but not when ingested with a
    complete diet; AgCi precipitate is formed in the gut,  and Ag is not toxic.
   •When Ag is added to soils, it is strongly precipitated and adsorbed by the
    soils.  Plants accumulate only traces of Ag, and no evidence of plant
    uptake which might comprise a  chronic  ingestion risk has been found.
    Most environmental concern about Ag results from toxicologists testing
    soluble Ag salts in purified waters. Never from sludge. Even when
    sludge was fed to livestock, sludge Ag was not toxic nor accumulated.
    Silver should be deleted from the list.

Thallium:  Although Tl appears to comprise a risk to plants or the food-chain
    from deposition of aerosols on plants, there is little evidence that sludge-
    applied Tl is moved into edible plant tissues.  Again, the studies of Lisk
    et al. using neutron activation provide adequate evidence that sludge Tl
    has not been found to comprise risk. Tl can be emitted from
    incinerators, and cement manufacturers commonly emit Tl and cause
    local enrichment of soils.

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 Tin: Sn is normally Sn * in the soil environment, and very insoluble.  Like TX
    and Cr, Sn is a good label for non-absorbed soil in the diet.  Sludges
    seldom have really high levels of Sn> and no evidence of plant uptake of
    Sn from sludge-amended soil has been reported.  Lisk included Sn in hi*
    studies by neutron activation. Actually, sludge Sn is not a risk to
    livestock which ingest sludge, in strong contrast with sludge Fe and F.
    Tin should be deleted from the list.

Titanium:  Ti is usually Ti4* in soils, and is very insoluble as TIO2.  Soil Tl is
    not found Inside plants, only as soil or dust contamination on the plants.
    Soil/Sludge Ti is so insoluble that it does not comprise risk even when
    Ingested by livestock. Titanium should be deleted from the list.

Vanadium:  In nutrient solutions, certain unstable V salts can be accumulated
    by plants, and vanadate interferes with ion uptake by ATPase enzymes in
    the roots. Little V is translocated to edible crop tissues. The Lisk work
    usually showed that-V'was not accumulated by crops, nor in animal
    tissues. Vanadium should likely be deleted from the list.

Iron: I am a little concerned that no one in your team chose to enter Fe
    {iron} or cobalt (Co) into the Round 2 review. In 1976-1979, a
    cooperative study in Maryland allowed us to characterize Fe  toxicity to
    cattle fed high Fe  U1%) and low Cu sludges on pastures.  When a
    sludge or compost with only about 4% Fe was surface-applied  on
    pastures or added to feeds in a feeding study with cattle, they  did not
    cause the Fe toxicity, but some accumulation of Fe in the spleen, liver,
    and duodenum was observed. Several other controlled feeding studies in
    the US  did not find evidence of Fe toxicity from ingested sludges with 1-
    2% Fe, and seldom found Fe accumulation is tissues. The usual action
    of excessive Fe Intake is to induce chronic Cu deficiency which causes
    joint disease.  Because Fe has poisoned livestock in several sludge
    experiments, and if high Fe sludges are found by monitoring, the sludge
    can be required to be injected  or incorporated rather than left on the
    surface, avoidance of sludge Fe risk is comparatively easy. When the
    ferrous  Fe in anaerobic sludges becomes oxidized in the soil,  or during
    composting, the ferric Fe has much lower solubility or toxicity to cattle.
    So the method of sludge processing and the concentration of Fe In the
    final product are important in prediction of animal risk. Humans seldom
    ingest sludges which are freshly anaerobic, and no evidence of  human
    risk from sludge Fe has been identified.

    In the Oklahoma miniature horses case, the horses were alleged to have
    suffered Fe toxicity, but the soil appears to have been the major source

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    of the Fe exposure. Historic observations of induced Cu deficiency on
    lateritic or other high Fe soils has been reported in cattle from many
    locations. Another ease in Virginia may have comprised Fe poisoning,
    but the details of the source of excess soluble Fe remain unclear.  Ona
    common symptom of Fe toxicity is red coloration of the duodenum from
    ferritln accumulation.  Tissues (liver; kidney, spleen, blood/serum) have
    increased Fe concentrations when higher Fe sludges are Ingested by
    livestock.

Cobalt: Because sludges normally do not contain high Co concentrations
    without unusual industrial discharge, no Co problems have been
    observed En sludge research. However, my analysis of the "Soil-Plant
    Barrier" indicated that plants could tolerate higher Co concentrations
    than can be tolerated by ruminant  livestock. Apparently vitamin B14 is
    formed in the rumen, and this form of Co causes toxicity in the livestock.
    Co feeding trials (see NRC, 1980}  have shown that 5-10 ppm Co In diets
    injures sheep and cattle. I have done a substantial risk assessment on
    Co for a compost to be made from wastewater treatment blosolids at a
    manufacturing plant of DuPont, and this could be made available to you
    upon request.  Thus, although no adverse effects of sludge-applied Co
    have been reported to date, it is at least possible to poison ruminants by
    Co in forage plants. Analysis can identify the very few high Co sludges
    and require practices to prevent adverse effects.

So, of all the elements  you have listed, Fe and F are the only ones with
sludge research showing a toxic environmental effect from sludges utilized
on land.  Please add Fe and Co to the list now. And delete Ai, Sb, Ba, Mn,
Ag, Sn, Ti, and V.                                                 '.

Organics with substantial vapor pressure Uoluene; 2-butanona; methylene
chloride; phenol; 2-propanone; toluene} are expected to be volatilized or
biodegraded during activated sludge treatment of the wastewater, and trace
residues will collect in the sludge. Each of these compounds is  readily
metabolized by soils, with short half-lives.  These should be deleted because
Round 1  consideration  of other volatile compounds showed that no residue
reached humans or livestock.

The 2,4-D, 2,4,5-T, and 2-(2,4,5)-TP are residues of pesticides  which have
lower use today because of their adverse effects in Agent Orange which was
contaminated with dioxins produced as byproducts. These compounds are
usually sprayed on the  plant, and metabolized fairly rapidly by tolerant plants,
but slowly by sensitive plants. These reactions are well reported in pesticide
applications at EPA. Because these  are not very lipophilic, they are usually

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 blodegraded rather than persistent in soils.

 Cyanides can accumulate in sludges after precipitation of ferricyanide by
 other metals. Soluble cyanide is present only at very low concentrations.
 Sludges have low levels of total CM, and essentially all sludge/soil cyanide is
 found to be bound to Fe.
                                               "*!

 I know little about CSa.  But these is little evidence it would survive aerobic
 treatment of the water.

 Co-planar PCBs, PCNB, Dioxins, Dibenzofurans, and endosulfan are
 persistent halogenated hydrocarbons. Detailed evaluation will be required for
 these compounds. But the toxicity endpoints for the halogenated
 hydrocarbons are seldom reached from these compounds in land-applied
 sludges. The Madison, Wl, studies showed that no significant transfer of
 sludge-applied PCBs was observed in  above ground plant biomass =
 forages. Direct ingestion of sludges allows digestion of these compounds
 from the sludge. Accumulation of dioxins in earthworm-food-webs is
 expected, but not yet shown to induce toxicity to animals.

 Nitrate accumulates in fields with aerobic soils after sludge has been
 incorporated.  Some plants accumulate excessive levels of plant nitrate
 {spinach, beet),  and comprise nitrate-poisoning risk to infants. Further,
 excessive nitrate accumulation in some forage crops can poison livestock.
 Nitrite seldom accumulates unless some toxic factor inhibits nitrification of
 the nitrite.  Because sludge application rate is limited  to the fertilizer
 requirement of the crop,  nitrate and nitrite so not require regulation.

 1 heard a story about tungsten toxicity in a field study in the UK, but no
 papers were prepared from the thesis and report to the funding agency. I
 hope to visit the University of Sheffield and obtain a copy of the thesis on
 May 12. Dr. Steven McGrath hypothesized that tungstate Interfered with
 use of moiybdate in plants by competition as a co-factor for an enzyme
 involved in N-fixation or nitrate reduction by the plants.

 Thus, several elements on the list are of potential importance because of
their phytotoxicity rather than food-chain-transfer.  These include Al, B and
 F.  Some comprise food-chain risk to livestock which  graze the fields (F; and
 possibly Be, Ba,  and Be).  Some are not dangerous to livestock even when
ingested (Ti, Sn, Sb, and  probably Sb). As noted above, Fe and Co also
comprise risk until sludge analysts provides the management Information
needed to prevent risk.

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As shown by the Round 1 contaminants/ Se and Mo are accumulated by
forage crops such that they comprise risk to the livestock rather than to
humans consuming garden crops in Pathway 3.  Mo needs to be finalized.
Several scientists have been conducting studies on Mo uptake by crops on
sludge-amended soils. High sludge Fe reduces Mo phytoavailability as noted
in my 1991/1992 comments  on 503 Mo limits in which I clarified .errors in
the database on Mo uptake from sludges. The potential role of sludge Fe
(and Al) in binding sludge F can sharply reduce fluoride risk assessment for
sludges.


Based on  widely accepted data about the trace elements on this list,  I .believe
that the following should be deleted from Round 2 now (AI, Sb, Ba, Mn, Ag,
Tl, Sn, TI, and V, and the volatile organics).  Others are only a risk in sludge
is ingested (Fe, F}, and some  are sufficiently phytotoxic (based on field
studies with sludge) that they might be regulated to avoid phytotoxicity): Al,
B, Mn. And Fe should be added to include a well characterized sludge risk
from anaerobic treatment conditions.  Cobalt is theoretically.toxic to
ruminant livestock after it is accumulated in forage  plants.


Please feel free to call or write me for further information if needed.   I
enclose several references which cover the Lisk/Furr papers, and have
several databases on the sludge-trace element literature in WordPerfect 5.1
which contain references on these rarer elements in sludges.


PLEASE CONFIRM RECEIPT OF THIS MEMORANDUM.


References cited in  letter to Hais:

Boyer, K.W., J.W. Jones,  D. Linscott, S.K. Wright, W.  Stroube and W.
Cunningham. 1381. Trace element levels in tissues from cattle fed a sewage
sludge-amended diet. J. Toxicol. Environ. Health. 8:281-295.
      VREF-VER/Copy [Sewage Sludge—CO: "Baxter et al.] "The levels of 20 elements (Al. Ca, Cd,
   Cl. Co. Cu. Fe. K, Mo. Mn. Mo. Na,  Mi. P. Pb, Rb. Sb. Se. V, and Zn ere reported for kidney, liver.
   musda, spleen, and brain tissues taken from two groups of 6 steers per group In a feeding study
   conducted at Colorado State University.  The control group was fed a normal feedlot cattlo ration
   and the test group was fed the sama ration amended with 12% (by weight) air-dried municipal
   sewage sludge, elemental levels ere also reported for the contra! and test diets, control and test
   faces, arid sewage sludge added to the diet. All samples were analyzed by 3CP-plasma emission
   cpectroccopy and neutron activation analysis.  Brief descriptions of the analytical methods are
   included, the levels of all metals determined were elevated In the test diet (as much as 19>fold for
   Cd) compared with the control diet. The levels of Pb and Cd in kidney and of Pb. Cd, and Cu ki
   Ever In tha test animals were high enough to causa concern from a lexicological standpoint If those
   tissues were consumed regularly by humans. None of the levels of any of the other elements in the
   control and test animals tissues were high enough to cause similar concern with respect to human
   consumption."
      Samples from the  2nd study, with Ft. Collins sludge when It was still high in Cd and Cu. Wat
   ashed samples. For higher concn metals, ran on ICP directly. For lower conen metals, adjusted to
   pH near 5 and used chelex resin to  collect metals from a larger aliquot, and than add stripped the

                                       8

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     metals into small volume for analysis.  Co was by NAA.  Co In kidney of (Control/Test) were
     0.020/0.041 f/gig FW; liver Co: 0.047/0.077; Muscle Co: 0.07/0.01?; Spleen Co: 0.02/0.02; Brain:
     0.009/6.019. Diet contained 0.09/0.43 ppm Co. sludge, 2.5 ppm; and f eces:0.43/1.60 ppm DW.
     /RLC-fl


 Capar, S.G., J.T. Tanner, M.H. Friedman and K.W. Boyer.  1978.  Multielement
 analysis of animal feed, animal wastes, and sewage sludge.  Environ. Sci. Technol.
 12:785-790.
        VREF-VER/Copy  (Sewage Sludge-CO:  Baxter at aJ.J "Animal excreta and sewage sludge  are
     currently being used as animal feed ingredients on an experimental basis. The levels of 30 elements
     are reported for a typical cattle feedlot diet, two dried cattle manures, a commercial  cattle waste
     product, tow dried poultry manures, and a metropolitan sewage sludge. The analyses arc
     conducted using neutron activation analysis. Induction coupled plasma spectroscppy. atomic
     absorption spectroscopy. and anodic stripping voltammetry.  The levels of most Inorganic elements
     are considerably  higher In animal wastes and sewage sludge than in traditional animal feeds. For
     most «iemem» tb« levels determined by several techniques are in good agreement. Problems of io«a
     of lead with precipitate formation,  accurate quantisation of elements present in high levels, and
     obtaining homogeneous samples for analysis are discussed.*  ,
        Worried about clement contamination of sludge and manure if these are used as  feed
    Ingredients, thus analyzed many elements using newer techniques (at that time).  The feedlot diet
    contained 0.10 ppm Co, while manures contained 1.1-2.2 ppm Co, and Denver sludge, 7.1 ppm Co.
    Also analyzed As. Ba. Be. Br. Cd, Cr. Cu. Eu. Hg. La. Mn. Mo. Pb. Rb. Sb. Sc. Se. Sn. Ti. V. Zn. Al,
    Ca. CI, Fe. K, Mg. Na. and P. Found considerable  contamination of samples with residues of e
    homogenlzer (for Co, Cr, and Ni from stainless steel).  Nete need for studies of risk and health of
    animals which consume these contaminated materials. /KLC-Q

Chaney, R.L. and J.A. Ryan.  1993.  Heavy metals and toxic organic pollutants  in
MSW-composts:   Research results on phytoavailabllity, bioavailability, etc.  pp.
451-506.  In H.A.J. Hoitink and H.M. Keener (eds.j.  Science and Engineering of
Composting: Design, Environmental, Microbiological and Utilization Aspects. Ohio
State University,  Columbus, OH.


Chaney, R.L., G.S. Stoewsand, A.K. Furr, C.A. Bacne and D.J. Usk. 1978b.
Elemental content of tissues of guinea  pigs fed Swiss chard grown  on municipal
sewage sludge-amended soil. J. Agr. Food Chem. 26:994-997.
       V  (Sewage Sludge-USDA: Chaney et al.-FEEDING] VREF-VER/Copy  HCo In Soil/Plant: Misc.
    Auth.) Sewage Sludge-USDA: Cheney et al.-BioavaiIabffityJ  Because we used neutron activation
    to analyze Co. data are available.  "Swiss chard was grown on soil amended with municipal sewage
    sludges from Baltimore and Washington, DC.  The harvested crops were fed at 20 or  28% of diet to
    guinea pigs for 80 days. Samples of soil, sludges, plant, and animal tissues were analyzed for up to
    43 elements. The elements Br, Ca. Co. Eu. Fe. NI. and Sr were found at higher concentrations In
    tissues of animals fed the chard cultured on sludge-amended soil than In control animals.
    Composting sludge prior to amending the soil appeared to render certain elements such ac Cd, Cu,
    NI. and Zn less available to Swiss chard subsequently  grown.'
       COBALT SUMMARY:  Chard was grown  on plots of Woodstown silt loam amended with 56
    Mg/ha of Baltimore digested sludge. 112 Mg/ha ef Blue Plains digested sludge, and 224 Mg/ha of
    composted digested Blue Plains sludge, and on control. Because the BP compost included some
    serpentine rock chips, compost and chard were higher In Co than the other sludges: Son * 9.1
    ppm; Balto  - 9.4 ppm; BP Dig - 8.0 ppm and BP Compost  =15 ppm DW. The chard (harvested
    at maturity, washed, rinsed, freeze»dried and ground]:  Control - 0.4; Balto - 0.8; BP Dig = 2.2;
    and BP Comp = 1.1 mg Co/kg DW. These results follow the pH of the plots rather than the Co
    content of the "sludge" or the amended soils. pH at harvest was 6.6, 5.0. 5.7, and 6.7 indicating
    that compost acted as a liming agent in contrast with sludge. Kidney of one of the 4  replicate

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    gulnaa pigs was analyzed for many elements, and all kidney, and fiver samples wora analyzed for Nl,
    Pb. and Cd.  Kidney Co was: Control •• 0.6: Balto » 0.7; BP Dig « 1.0; BP Cemp * not reported.
    No significance test was possible on (ha Co data. Ni was increasad in Baltimore chard and
    kJdney/llver of the guinea pigs; Although ail sludge grown chard was higher in Cd than tlh» control,
    no Increase was found In kidney, or liverf Attribute this to presence of 2n in same tissue. The
    guinea pigs did equally weQ on ail sources of chard, growing 450 g in the 80 days.
Davis, R.D.  1980.  Uptake of fluoride by ryegrass grown in soil treated with
sewage sludge.  Environ. Pollut. 81:277-284.


Decker, A.M., R.L Chaney, J.P. Davidson, T.S. Rumsay, S.B. Mohanty arid R.C.
Hammond.  1980. Animal performance on pastures topdressed with liquid sawage
sludge and sludge compost, pp 37-41. In, Proc. Nat. Conf. Municipal and Industrial
Sludge Utilization and Disposal.  Information Transfer, Inc., Silver Spring, IMD.
       *  RLC.JQ

Francois, L.E.  1986. Effect of excess boron on  broccoli, cauliflower, and radish.
J. Am. Soc.  Hort. Scl. 11.1:494-498.

Francois, L.E. and R.A.  Clark.  1979. Boron tolerance of twenty-five ornamental
shrub species. J. Am. Soc.. Hort. Sci. 104:319*322.

Furr, A,K., W.C. Kelly, C.A. Bache, W.H. Gutenmann, and D.J. Lisk. 197(5.
Multi-element absorption by crops grown on Ithaca  sludge-amended soil. Bull.
Environ.  Contam. Toxicol.  16:756-763.
       V  RLC-Q                    .

Furr, A.K., T.F. Parkinson, D.C. Elfving et al.  1981. Element content of vegetable
and apple trees grown on Syracuse sludge-amended soils. J. Agrie. Food Cham.
29:156-160.
       V  RLC.Q

Hogue, D.E., J.J. Parrish, R.H. Foote, J.R. Stouffer, J.L. Anderson, G.S.
Stoewsand, J.N. Telford, C.A. Bache, W.H, Gutenmann and D.J. Lisk.  1984.
Toxicologic studies with male sheep grazing on municipal sludge-amended soil.  J.
Toxicol. Environ.  Health  14:153-161.
       VREF-VER/Copy  [Heavy Metals in Soil/Plants: Lisk et al.— SLUDGE]  "Growing sheep were
    grazed  for 152 days on grass-legume forage growing on soil that had been amended with municipal
    sewage sludge from Syracuse, NY, at 224 metric tons/ha. Cd was higher, but not significantly IP
    > 0.05), In  tissues of sheep fed the sludge-grown forage as compared to controls. No significant
    differences between the sludge or control treatments were found In weight ef the complete or
   •cauda epididymls  or in % progressive motility of cauda epididymal sperm.  The sludge-treatment
    group had significantly larger testes (P< 0.025) when expressed as a percentage of body weight,
    end higher blood uric add values IP < 0,05). There were no observable changes In tissue
    ultrastructure of Ever,  kidney, muscle, or testes as examined  by electron microscopy in either of the
    treatment groups. There were no significant differences for rate of animal weight gain, carcass
    weight, dressing percentage, or quality or yield grade of the carcass between tha treatment
    groups."
       Syracuse sludge.  April 1980. applied weathered (1 yr) sludge to subsoil of Chanango gravelly
    loam, pH 7.1. Amended soil was pH 6.7. Collected grass-legume hay for feeding studiai; in 1980
    and" 1981. In 1982, used for grazing study. Had been planted with alfalfa, blrdsfoot trefoil,


                                         10

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    timothy, and brornegrass.  3 month old 'Mortem' sheep used to graze the pastures for 152 days.
    Each animal was also fed 250 g feed concentrate dally, and ad Ub water. Composite sott from fi«id
       Sludge contained S3 ppm Cd; forage 0.09 vs. 1.14 pprnDW Cd. Feed concentrate contained
    0.21 ppm Cd.  Kidney contained 0,55 ±0.14. ppmDW Cd vs. 0.83 ±0.17 NS; liver contained
    0.22 ±0.04 vs. 0.40 ±0.08 NS; musde contained 0.03*0.01  vs. 0.09  ±0.04 ppmDW Cd NS.
    Rate of gain was higher for sludge than control animals NS.
 Kienhoiz, E.W;, G.M. Ward, D.E. Johnton, J. Baxter, G. Braude and G. Stern.
 1979. Metropolitan  Denver sewage sludge fed to feedlot steers,  J. Anim. Sci.
 48:735-741.
       VREF-VER/Copy [Sewage Sludga-CO:  Baxter, Kienhoiz. et a!.] 'Feadlot steers received 0, 4,
    or 12% Metropolitan Denver sewage sludge on a dry weight Intake basis for a 94-day finishing
  .  period.  Th« sludge was anaerobically digested primary sludge that had been treated with
    poly electrolyte to aid in dewstering during vacuum filtering.  K was then dried to 35% water prior to
    mixing Into the pelleted diet given the steers.  Cattle (6 on each treatment) were slaughtered and
    kidney,  liver, musde, bone, brain, blood. lung, spleen, and fat were analyzed for As. Cd, Cu,.Hg,
    Mo. Ni,  Pb, Se, and Zn.            .                                  .
     .  "Growth of the sludge animals was less than controls (P < 0.02S) because sludge,  apparently,
    provided no energy. Sludge ingestion caused no pathology. All 10 inorganic elements except M
    were increased In one or more body tissues following the 94 day sludge Ingestion. Percentage
    whole carcass  retentions of ingested minerals were estimated as follows: 0-2% As. 0.04% Cd,
    0.3% Cu.  0.07% Hfl, 0.2% Mo, < 0.006% NI. 0.6% Pb, 1.3% Se. 0.2% Zn. and 32% f. Steers
    retained low amounts of the toxic heavy metals from sludge Ingestion."
       Sludge containad (ppmOW): 1.3 As. 21 Cd(die« 0.025. 0.65, and 1.9 ppm), 710 Cu(diats 3.2,
    31. and 86 ppm), 11 Kg, 40 Mo, 125 NI, 780 Pbfdiets 0.6, 26, end 77 ppm). 5.4 Se. 1500 Zn, and
    200 F.  Diet was pelletted  corn + cottonseed mean + molasses + limestone + NaCI.  corn silage ad fib.
    Bone samples were taken from the proximal half of the tarsal bone. Samples digested with low
    metal acids. . For many elements (not kidney or liver), sample metals were extracted by APDC.
    crystals collected, and filtered;  Taken Into small volume for analysis. Carbon rod used for some
    samples. Good QA/QC program.  At 12% sludge. As was increased in fiver, Cd in fiver and kidney,
    Cu Increased in liver, Hg increased in liver, kidney and muscle.  Mo Increased in bone and liver, Pb
    Increased in Ever, kidney, bone, and blood: Sa increased  In blood: Zn increased only in Uver.  At
    both rates. F increased In bone. NI did not Increase in any tissues.
       Pb in tissues: Liver 0.2a 3.3b, 4.6c ppmDW for 0/4/12% sludge: kidney: 0.9a 12.2 b 15.8 b;
    Muscle: 0.2 . 0.2: bone:1a, 4b, lie: blood: 0.12a. ., 0.82b; fat:0.16, ., 0.16.  Cd In tissues: iiver:
    0.2a 0.5b  0.4b: kidney:  l.la 2.5b 2.4b; muscle: <0.01, ., <0.01. Hg: Uver:0.01a 0.06b 0.14e;
    kidney 0.1 a, 0.45b, 0.9c. Cu: liver:  124a, 260b 240b.
Neary, D.G., G. Schneider, and D.P. White.  1975.  Boron toxicity in red pine
following municipal wastewater irrigation. Soil Sci. Soc. am. Proc. 39:981-982.

NRC (National Research Council).  1980.  Mineral Tolerance of Domestic Animals.
National Academy of Sciences, Washington, D.C.  577pp.
       •  RLC-Q

Rea, R.E.  1979.  A rapid method for the determination of fluoride in sewage
sludges.  Water Pollut. Contr. 78:139-142.

Sanson, D.W., D.M. Hallford and G.S. Smith.  1984.  Effects of long-term
consumption of sewage solids on blood, milk and tissue elemental composition of
breeding ewes. J.  Anim. Sci. 59:416-424.
       VREF-VER/Copy  ISewaga Sludge-NM: Smith et a!.]  "Fine-wool ewes received for 2 yr a
   complete palleted diet (11% protein) or the basal diet fortified with 3.5% cottonseed meal  (CSM,

                                          11

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     12* protein} or gamma-Irradiated (1 megarad) dried solids (SS. 12% protein) from primary
     (undigested), sewage (Us Graces, NM municipal sewage).  Five awe* fad each diet were sampled to
     determine Ag, Ca, Cd, Co. Cr. Cu, Fa, K, Mg. Mn, Na. M. P, Pb, and Zn In blood, milk and tissues.
     Tissues and blood ware sampled at slaughter 40 days after weaning of lambs. Mean whole blood
     mineral concentrations were similar (P > 0.05) among treatments 3 d postpartum; however, at 42
     days after lambing both basal and sewage fed awes had elevated blood Ca compared with awes fed
     CSM. No biologically Important differences were detected In the concentrations of elements in milk.
     Ewes fed SS had lower (P<0.05) flood Fe than animals in the other groups. Sewage-fed ewe« alee
     had higher {P<0.05} liver Fe (1092 ppmDw) than basal-fed ewes (626 ppm) whereas Fe In CSM-fed
     awes (873 ppm) was similar to both.  Basal-fed animals had 1.1-1.3 times more (P<0.05> liver Mg
     and 2-to-3-foid higher liver Na  than CSM or SS.  Uvars from SS-fed ewes had higher concentrations
     0.051. element concentrations In
    whole blood at weaning, after SB days of the feeding trial and at slaughter did not differ (F'>0.05)
    between dietary groups. Serum chemistry determinations showed no biologically meaningful
    patterns related to diets. Lambs fed SS had higher (P<0.05) canon, of Cu in livers (51.1 vs. 34.3
    //g/g) and Pb In kidneys (4.0 vs. 2.2 ±0.3 j/g/g and lower Mg in kidneys. None of the elements in
    spleen and muscle tissue differed  (P>0.05) between diet groups. Lambs fed SS had  elevated
    (P<0.05) bone Co, Cu. Fe. K, and Na compared with those of CD. Lead concn. In bone were
    Increased (P<0..05) by Ss over CD (30.5 vs. 26.3). but Cd and Zn did not differ. A feedlot diet with
    7% SS did not appear to adversely affect growth or carcass characteristics of lambs. Serum
    clinical profiles and chemical  elements in blood and tissues were affected negligibly by SS as 7% of
    the diet."
       Sludge composition averaged:  3  Cd, 470 Cu, 9233 Fe, 110 Mn, 9  diet consumption, and
    lower gain rates. Blood Cu not affected by sludge Ingestion. Uver contained: Cd < 0.07/0.07
    ppmDW; Cu 34.3/51.1; Fe 179/190;  Pb 2.5/3.5;  Kidney: Cd <0.07/<0.07; Pb 2.2a/4.0b;  bone:
    Pb 26.3a/30.Bb.
Smith, G.S., D.M. Hallford and J.B. Watklns, III.  1985.  lexicological effects of
gamma-Irradiated sewage solids  fed as seven percent of diet to sheep for four
years.  J. Anim.  Sci.  61:931-941.
                                            12

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        VREF-VER/Copy [Sewage SIudge-NM: Smith at at.] 'Breeding awes ki dryiot ware fed pelleted
    complete diets with 3% cottonseed meal {CSMJ or 7% dried, sarnma-lrradiated sewage so&ds
    (DGSS) for 4 yr.  Cytochrome P-450 content and enzyme activities for xenobiotic*
    biotrarisformatlons ware assayed in livers after 3 yr and In liven, kidneys and Heat tissue after 4 yr.
    Dietary DGSS caused no Increase in P-450 and few changes In activities of oxldativa, hydrolative,
    and conjugates blotransformatlonaJ enzymes.  Consumption of DGSS for 4 yr caused slight
    enlargement of spleens (1.1-fold) and ovaries (1.3-fold, P<0.10). but no change In size of fiver*.
    kidneys, hearts, adrenals and thyroids {R>0.10). nor Pver vitamin A levels (P>0.10). Of 22
    refractory lipophilic  residues  assayed in abdominal adipose tissue, few were detected and of those
    detected DGSS caused none to exceed normal levels.  Dietary DGSS increased IP < 0.01) Fa In Ivan
    1.5-fold and In spleens 5.6-fold, and Increased Cu in Overs 1.3-fold (P<0.01) and in  kidneys 1,2-
    foid. Dietary DGSS increased Cd level* in fivers but not in kidneys or spleens  {P>0.10); yet all Cd
    levels were within ranges for livestock fed conventional feed.  Dietary DGSS caused  no increase
    (P>0.10) In levels of Ag. Caf Cr, Hg. K. Mg. Mn, Na, M. P. pfa. or Zn in livers, kidneys or spleens.
    There were no histopathological  lesions of toxicosis except mild hemosiderasis of spleens.
    Consumption of a diet with 7% DGSS throughout 4 yr caused no hazardous accumulation of toxic
    elements and little, if any, evidence of toxiclty."
       Undigested sewage solids (primary and activated) from Las Crucas. NM. Dried and irradiated.
   .Contained:  0.58% Fa; 606 ppm Zn; 405 ppm  Cu; 361 ppm Cr: 150 ppm Pb; 99 ppm Pb; 11 ppm
    Mi; <5 ppm Hg: <1 ppm So. 41.5% ash.  Liver Fe was Increased. 849±387 (SD) vs. 1303 ±291
    ppm DW. Uver Cu was raised:   597±308 vs. 761 ±259 ppmDW. liver Cd [<0.03  vs. 1.47*0.30
    ppmDW] was raised, but kidney  was not [2.8±0.3 vs. 3.6±0.6 ppmDWJ.   Pb was unchanged and
    at very-low levels In Over, kidney, and spleen «0.10 ppm DW).  p.p'DDE was increased in fat, but
    PCS and other chlorinated hydrocarbons were not increased. The animals were mature, tine-wool
    ewes of Rambouillet breading. /BLC«Q

Vimmerstedt, J,P. and  T.N. Glover. 1984.   Boron toxicity to sycamore on mihesoil
mixed with sewage sludge containing glass fibers.  Soil Sci. Soc. Am. J. 48:383-
393.
                                            13

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 TABLE 5.  Maximum tolerable levels of dietary minerals for domestic livestock in
 comparison with levels in forages.
 	'——~~	 Eiement "Soil-  Level in
 Plant-Foliage* MaxirhumJLevels Chronically Tolerated*       Plant
                                Barrier" Normal  ghyto.toxic  Cjsittfi   Sheep
 Swine   Chicken
            -mg/kg dry foliage	——mg/kg dry diet	--
As. Inorg. yes 0.01*1
B
Cd'
Cr3*
Co
Cu
F
Fe
Mn
Mo
NI
Pb'
SQ
V
Zn
yes 7-75
Fails O.i-l
yes O.I-l
Fail? O.ON0.3
yes 3-20
yes? 1-5
yes 30-300
? 15-150
Fails 0.1-3.0
yes 0.1-5
yes 2-5
Fails 0.1-2
yes? O.I-l
yes 15-150
3-10 50. 50. 50. 50.
75 150. (150.) (150.) (150.)
5-700 0.5 0.5 0.5 0.5
20 (3000.) (3000.) (3000.) 3000.
25-100 10. 10. 10. 10.
25-40 100. 25. 250. 300. .
40. 60. 150. 200.
1000. 500. 3000. 1000.
400-2000 1000. 1000. 400. 2000.
100 10. 10. 20. 100.
50-100 50. (50.) (100.) (300.)
30. 30. 30. 30.
100 (2.) (2.) 2. 2.
10 50. 50. (10.) 10.
500-1500 500. 300. 1000. 1000.
£/  Based on literature summarized in Chaney et al. (1982).
&/  Basad on NRC (1980). Continuous long-term feeding of minerals at the
maximum tolerable levels may cause adverse effects.  Levels in parentheses were
estimated (by NRC) by extrapolating between animal species.
sJ  Maximum levels tolerated were based on Cd or Pb in liver, kidney, and bone in
foods for humans rather than simple tolerance by the animals.
From:  Chaney and Ryan, 1993.

   Boron Phytotoxicity: In contrast with municipal sewage sludge, MSW-compost
contains substantial levels of soluble boron (B). B toxicity from sewage sludge
application was reported only for an unusual case of a sensitive tree species
growing In soils amended with a sludge containing lots of glass fibers (Vimmerstedt
and Glover, 1984; see also Neary et al., 1975, regarding high B levels in
phosphate-free detergents).  The glass fibers contained borosiiicate and release of
B caused phytotoxicity. Research has shown that much of the soluble 8 in MSW-     _.
compost comes from glues (Voik, 1976).  It has long been known that plant         IM
samples placed in paper bags can become contaminated from B from glue  used to

                                     14

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 hold the bag together.  E! Bassarn and Thorman (1979) and Gray and Biddlestone
 (1980) noted that the B level in MSW-composts was quite variable as might be
 expected if composts are not well mixed.
    In general, B phytotoxicity has occurred when high application rates were used,
 and B-sensttlve crops were grown.  However, when MSW-compost is used at
 fertilizer rates In normal fields, the B might be important as a fertilizer rather than
 as a potential phytotoxicity problem.
    Boric acid  and most  berates are quite water soluble, although B can be adsorbed
 on clays and by organic matter.  Low soil pH facilitates B uptake by plants because
 the H3BO3 molecule (predominant form at lower soil pH) is absorbed by roots rather
 than anionic borates (Oertli and Grgurevic, 1975).  Although most B toxicity has
 been reported on alkaline soils, this  is due to the lack  of leaching for most of these
 soils.  Excess applications of soluble B are much more phytotoxlc in acidic soils,
 and liming can correct B phytotoxicity.  The usual liming action of compost should
 help prevent this problem.                  .
    There are large differences among crop species In tolerance of excessive soil B.
 Some crops are very sensitive, and these are the species which have suffered
 phytotoxicity from compost-applied  B (bean, wheat, and mum).  Francois has
 summarized the significant differences among several  groups of crops (Francois
 and Clark, 1979; Gupta, 1979; Francois, 1986). Ornamental horticultural species
 have been examined to  some extent (information on Individual species can be
 found by literature searching),  but many horticultural crops have not been studied.
 This is one research need related to  practical microelement phytotoxicity from
 compost.
    Perhaps the first report on B toxicity from MSW-compost is that of Purves
 (1972) who noted B phytptoxicity to beans on field plots which  received high rates
 of MSW-compost. The  full description of the compost experiment is reported in  :'
 Purves and Mackenzie (1973). and a careful examination to prove  B phytotoxicity
 was reported by Purves and Mackenzie (1974). Bean  (but not potato or other
 species examined) suffered severe yield reduction at high compost rates; this yield
 reduction was proportional to rate of compost application.  Bean is known to be
 especially sensitive to B phytotoxicity.  Gray and Biddiestone (1980) also found B
 phytotoxicity In sensitive species grown in field plots with high rates of MSW-
 compost.
   Gogue and Sanderson (1975) reported B phytotoxicity to chrysanthemums in
 potting media  containing MSW-compost.  Foliar analysis clearly supported the
 conclusion that B was toxic and that Mn, Cu, Zn, and  other, elements were not at
 toxic levels. They conducted a calibration experiment  to determine the sensitivity
 of chrysanthemums (Gogue and Sanderson, 1973), and the levels found in the
 mums grown on  the test media were In the phytotoxic range,  in their research,
they adjusted the pH of  the media to 6 using sulfur, rather than allowing the MSW-
compost to raise the pH of the media. This probably contributed to the severity of
B phytotoxicity observed. Some other horticultural species also  suffered  B
phytotoxicity in compost-containing  media (GUUam and Watson,  1981).  Sanderson
 (1980) reviewed B toxicity in compost amended potting media.   In contrast to
MSW-compost, sewage  sludge composts with wood chips have  not been found to
 cause B phytotoxicity  (Chaney, Munns, and Cathey, 1980).  Only a few acid-loving

                                    15

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species require acidification of media to do well on neutral compost-amended
media.
   Interestingly, because the B which causes phytotoxiclty is water soluble, the B
phytotoxlcity problem from MSW-compost Is short-lived. Purves and Mackenzie
11373} noted that pre-leaehing MSW-compost prevented B phytotoxicity. Other
studies noted that the B-phytotoxlcity occurred only during the year of application,
and that soluble B was leached out of the root zone over winter (Volk, 1976) or by
leaching potting media with normal horticultural watering practices. Sanderson
(1980) noted that perllte also adds B to potting media, and that use of both may
cause B toxiclty when either periite or MSW-compost alone might not have don*
so. Lumis and Johnson (1982} studied leaching of B in relation to toxicity of salts
and B to Forsythia and Thuja.  They reported that a simple leaching treatment
removed excess soluble salts, but was unable to remove enough B to prevent
phytotoxlcity (the compost they studied contained 225 mg B/kg, higher than most
reports}.  Nogaies at at. (1987} also found compost-applied B leached quickly such
that crop  B was reduced in each successive ryegrass crop.
   B phytotoxicity Is significantly more severe when plants are N-deficiant IGogua
and Sanderson,  1973; Nogaies et a!., 1987; Gupta et al., 1973). This makes the B
in MSW-compost which is not properly cured (to avoid N immobilization) potentially
more phytotoxic than in well cured composts.  Further, B flows with the
transpiration stream and accumulates in older leaves,  in environments with low
humidity,  more transpiration occurs (e.g., greenhouses), and B toxicity is more
severs.  B and salt toxicity are easily confused; both are first observed in leaf tips
or margins of older leaves. Diagnosis of B phytotoxicity requires a knowledge of
relative plant tolerance of  B, or analysis of the leaves bearing symptoms.
   Thus, in general use, compost application at a reasonable fertilizer rate would
simply add enough B to serve as a fertilizer for B-deficiency susceptible crops such
as alfalfa or cole crops.  However, use of MSW-compost at high rates in soils or
potting media  could cause phytotoxicity if high soluble B were present. The B
phytotoxicity would not be persistent because soluble B would leach from The root
zone with normal rainfall or .irrigation. Compost-applied B would be more
phytotoxic in N-deflcient soils, which might result from application of Improperly
cured compost.  Water soluble B should be one chemical which is regularly
monitored in MSW-composts so that the need for warning about rates of
application and use with sensitive crops can be Identified. Deliberate use of MSW-
compost as a B fertilizer for high B-requiring crops such as the cole crops (cabbage
family) might become a  regular agronomic practice. Sources of soluble B In
modern MSW-compost should be evaluated, and alternative to B use identified.
                                     16

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                  Reprinted from the Journal of Environmental Quality
          Vol 19, no. 3, July-September 1990, Copyright C 1990, ASA. CSSA, SSSA
                   677 Sooth Segoe Road. Mmdinon, WI 53711 USA
Plant Uptake of Pentachlorophenol from Sludge-Amended Soils

               Cheryl A. Bellin and George A. O'Connor

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                   Plant Uptake of Pentachlorophenol from Sludge-Amended Soils

                                  Cheryl A. Bellin and George A. O'Connor*
                      ABSTRACT
    A greenhouse study was conducted to determine the effects of
  sludge OB plant •ptmke of "C-prntarslorophtsMC (PCP). Plants fe-
  clwied tall tacae(FextmemmTm*di*ma* Schreb.), kttace (£«•«• je-
  ft'wi L.), csmt (Dometts carota L,), and chfle pepper (Comou* am-
  m»m L.X Minimal intact PCP was detected ia the fescue and lettoee
  by gas chroamtognphy/inasf spectranwtry (GC/MS) analysis. No
  intact PCP was detected in the carrot tissue yrtrartt. Chfle pepper
  was not analyzed for intact PCP became netfaykoe chloride extracts
  contained minimal "C. The GC/MS analysis of caQ extracts at har-
  vest suggests a half-life of PCP of abort 10 d independent of stodge
  rate or PCP loading rate. Kapid degndatioa of PCP is die soil
  apparently linked PCP anSabflity to the plant. Bioeonceotntfoa
  factors (dry plant wt/initial soil PCP coocentratio*) based oa intact
  PCP were <(UH for aO craps, iism ilhn tittle PCP •stake. That,
  food-chain crop PCP intake in these alkaline sofls sbooJd not limit
  land application of stodge.
     LAND APPLICATION of sewage sludge is an inexpen-
      sive and convenient method of sludge disposal
 that provides plant nutrients and improves soil struc-
 ture. The potential bioavailability of toxic organics
 that can contaminate some sludges (e.g^ polychlori-
 nated biphenyls) may limit sludge utilization in agri-
 cultural settings, however. The large number of toxic
 organics that can contaminate sludges, complex anal-
 ysis, and unlimited environmental conditions makes
 it  virtually  impossible to study each compound in
 every setting. Therefore, a compound is selected based
 on physical and chemical properties  to represent a
 group of compounds.
   Chlorophenols are a group of ionizable organic com-
 pounds of environmental concern. Chlorophenols are
 not generally detected in sludges nationwide.  How-
 ever, .156 of 223 industrial and municipal sewage
 sludges from Michigan contained pentachlorophenol
 (PCP) at concentrations ranging from 0.2 to 8 490 mg
 kg-' dry weight (Jacobs et al., 1987). The median con-
 centration of the PCP contaminated sludges was 5 mg
 kg"1-
   The widespread use of PCP as a wood preservative
 and general biocide has lead to contamination of air,
 food, sediment (Bevenue and Beckman, 1967), water,
 and municipal sewage sludge (Buhler et aL, 1973). Pen-
 tachlorophenol is categorized as very toxic [oral LDso
 =  146 mg kg-1, rat (Rattus norvegicus); Crosby, 1980]
 and is mutagenic in MP-1 yeast strain (Fahrig et al.,
 1978). The generally low PCP concentration in con-
 taminated sludges (5 mg kg-1) would be reduced 50 to
 100 times during land application of sludge at normal
 agronomic rates (22.5-45 Mg ha-1). Accumulation of

 Both authors, Dep. of Agronomy and Horticulture, New Mexico
State Un iv.. Las Cruces, NM 88003. Journal Article no.  1499. Agric.
Exp. Stn., New Mexico State Univ. Although financial support for
2?L!?fe *?! Provjded «» Pan by Cooperative Agreement CR-
8126874)2 with  the USEPA, this report has not had USEPA's re-
quired peer and policy review and does not necessarily reflect the
views of the agency. Received 14 July 1989. "Corresponding author.
Published in J. Environ. Qual. 19:598-602 (1990).
  PCP in food-chain crops would not likely adversely
  affect humans at the resulting  PCP soil-sludge con-
  centrations.
    Bioavailability of nonpolar compounds such as PCP
- depends on the extent of sorption by the soil organic
  fraction and other transformation processes (Hamalcer
  and Thompson, 1972). Sludge additions increase the
  soil organic fraction and thus possibly alter PCP bioa-
  vailabDity. The chemical characteristics also contrib-
  ute to the complexity of PCP  sorption in the soil-
  sludge system. Pentachlorophenol is a.weak acid (pK,
  - 4.74; USEPA, 1979) and sorption increases with
  decreasing soil pH (Lagas, I988a; Baaerji et al., 1986)
  possibly altering the bioavailability of PCP in soils.
    Uptake of I4C by crops grown in "C-PCP treated
  soils has been reported; however, actual PCP and me-
  tabolites were not verified (Kloskowski et aL, 1981;
  Topp et aL, 1986). Topp et aL (1986) reported signif-
  icant >4C uptake for barley (Hordeum vulgare L.) after
  1 wk in a soil with a  pH of 6.4. However, I4C in the
  plant was attributed  to rapid degradation and min-
  eralization of PCP followed by assimilation of I4CO2.
  On the contrary, CasterHne etaL (1985) reported intact
  PCP uptake by spinach plants (Spinacia oleracea L.)
  and soybean plants [Glycine max (L.) Merr.} from an
  acid soiL  Methoxytetrachlorophenol, 2,3,4,6-tetrach-
  lorophenoL  pentachloroanisoL and 2,3,4,6-tetrachlo-
  roanisol were the primary metabolites detected in the
  plant tissue. The purpose of this experiment was  to
  determine the effects of sludge on PCP uptake by
  plants grown in alkaline soils in  the greenhouse.

          MATERIALS AND METHODS
  . The soils used in this study were a Glendate clay loam
 ffme-silty, mixed (calcareousX thermic Typic Torrifluvent]
 and a Biucpoint sandy loam (mixed, thermic Typic Torrip-
 samment), with pH values (water paste) of 7.8 and 8.3, re-
 spectively. The sofls were air-dried and sieved (6.25 mm)
 prior to the experiment.
   A municipal sewage sludge obtained from Albuquerque,
 NM, was anaerobically digested, air-dried, and gamma ir-
 radiated (II7Cs 10 kGy) to reduce pathogens. The sludge was
 ground to <2 mm and amended to  the soils at rates of 0,
 22.5, and 45 Mg ha-' (0,  10, and 20 g kg-')- The sludge was
 PCP-free, <1  mg kg-1 as analyzed by gas chromatography
 with a flame ionization detector (USEPA method 625).
   Reagent-grade PCP (Chemical Dynamics Corp., South
 Plainfield, NJ) and "C-PCP (Sigma Chemical Co., St. Louis,
 MO) (specific activity 455.1 MBq mmol-', uniformly ring-  ,
 labeled) were used to obtain desired PCP rates (0, 0.1, 0.6,
 1.1, and 5.1  mg kg-').
   Fescue (Festuca anatdinacea Schreb., 'Ky 31') and three
 foodchain crops: lettuce (Latuca saliva L.,  'Great Lakes'),
 carrot (Dauaa carota L, 'Nantes Scariet'X and chile pepper
 (Capsicum, annum L., 'Espanola Improved*) were grown in
 a greenhouse. The foodchain crops were chosen to represent
 a leafy crop, a root crop, and a fruit crop, respectively. Treat-
 ments were duplicated.
               Greenhouse Procedure
  Soil, sludge, and fertilizer (phosphate fertilizer 920 kg P2O5
ha-1) totaling 4 kg were mixed in a twin shell blender (18 kg
                                                   598

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                           BEUJN & O'CONNOR: PLANT UPTAKE OF PENTACHLOROPHENOL
                                                  599
  capacity) for S min. This soil-sludge mixture was placed in
  two pots (2 kg nor1) and leached to remove excess salts.
  After drying, soil-sludge mixtures were spiked with '•'C-PCP
  solutions (20 mL of 9.1 .AS Nad containing 740 MBq I4Q.
  The soil was mixed in a twin shell blender for 3 min and
  weighed into 18-cm diam. pots (2 kg pof). Drainage holes
  in the pots were covered with fiberglass mesh. A 100-g sam-
  ple of the soil-sludge mixture was retained for verification
  of "C-PCP application rate.
    Seeds were placed on the soil surfaces and covered with
  1 cm of soil previously removed from the pot The pots were
  then watered by a drip irrigation system to  80% pot water
  holding capacity and maintained at this moisture content
  gravimetneally. A total of 16 h daylight was maintained (ad-
  ditional light fr°m c&bt 400-W sodium lamps). Tempera-
  tures ranged from IS to 40 *C Liquid calcium nitrate fer-
  tilizer (equivalent  to 360 kg N ha-')  was added to the
  Bluepoint soil to compensate for N available in the sludge
  treatments. The experimental design was a randomized com-
  plete block for the lettuce, carrot, and chile and a completely
  random design for the fescue.

                Plant and Son Sampling

   Fescue was grown in the Bluepoint soil and the Glendale
 soil for 34 and 42 d, respectively. Lettuce was grown for 58
 d, carrot for 79  d, and chile pepper for 115 d.
   Plants were cut 2 cm above the soil surface to avoid con-
 tamination from the soil Chile fruits were cut from the fo-
 liage and carrot roots were removed from the soiL pie carrot
 roots were washed in an ultrasonic bath with deionized water
 for 5 min.
   Fresh weights of each fraction (combustion and extraction
 fractions) were recorded for an plant parts. The fraction for
 combustion was oven-dried at SO °C, reweighed, and ground
 in  a. Wiley mill with a 20-mesh screen. Extraction samples
 were stored in Ziploc bags in a freezer at —10 °C
   Soil samples, consisting of four 2-cm diam. cores to the
 depth of the pot (100 g), were taken from each pot at each
 harvest The soil samples were divided into two fractions:
 one for combustion and one for extraction. The samples for
 combustion were air-dried and ground with a mortar and
 pestle. The extraction samples were stored in Ziploc bags in
 a refrigerator at  5 *C               .

                 Analytical Methods

   Combustion.  Ground, air-dried, 300-mg soil samples and
 ground, oven-dried, 50-mg plant samples were replaced in
 boats, covered with activated alumina/cupric oxide (5:1 w/
 w), and combusted at 1000 *.C (Lindberg furnace) for 8 min
 under a stream  of Oj (150 mL min-1). Evolved "COj was
 trapped in a solution of 8 mL ethbxyethanolethanolamine
 (3:2 v/v) and 10 mL Ready Gel cocktail (Beckman). Samples
 were counted by liquid scintillation (LS) with a Beckman
 LSI800 counter.  Blanks and standards were combusted and
 counted to determine background counts (40 disintegrations
 per minute, dpm), oxidation efficiency (about 0.95),  and
 counting efficiency (0.65). The mean radioactivity was 0.184
 ± 0.018 MBq kg-' soil-sludge mixture in all PCP-containing
 treatments.
  Extraction Procedure. Soil and plant samples containing
 the highest '^C concentrations were extracted and analyzed
by LS counting and gas chromatography with mass spec-
trometer detector (GC/MS). Samples were extracted with a
procedure modified from Casteriine et aL (1985). The orig-
inal procedure extracted PCP, lower chlorinated phenols,
and anisols individually from plant and soil samples (93.2%
total plant extraction efficiency). This procedure was  sim-
plified because individual FCP metabolite identification was
not attempted.
    Fine roots were removed from sofl samples and 10 g of
  soil and 10 mL concentrated HQ were combined in glass
  centrifuge bottles, and heated m an oven at 60 *C overnight
  After cooling, the acidified soils were extracted with 50 mL
  methylene chloride. The bottles were stoppered, shaken for
  2 min, and centrifuged for 5 min at 2000 rpm (750 X g),
  The methylene chloride was removed and collected in a
  beaker. The soil mixture was extracted three more times for
  a total methylene chloride volume of 125 mL,
    Frozen plant samples were homogenized in  a Waring
  blender with 100  mL, 0.2 M Hd for 5 iron. The mixture
  was transferred into a 200-mL glass centrifujie bottle, 100
  mL methylene chloride added, and the bottle stoppered. Af-
  ter shaking for 2 inin, the inixture was centrifui^ for 4 rnin
  at 1000 rpm (300 X g). The methylene chloride was removed
  and collected into a beaker. The plant and acid  mixtures
  were extracted three more times with 50, 25, and 25 mL
  methylene chloride. All extracts were combined.
   Extract Cleanup. Soil and plant methylene chloride ex-
  tracts were evaporated to 25 mL. A 2-mL fraction of the soil
  extract was evaporated to dryness in a LS vial, dissolved
  with scintillation cocktail, and counted by LS, A 2-mL frac-
  tion of the plant extract was evaporated to dryness in a LS
  viaL Bleach (0.75  mL of 5.25% sodium hypochlorite) was
  added and the suspension heated at 50 °C for HIT. A mixture
  of acetic acid and Ready Gel cocktail (18 mL of 3:400 v/V)
  was then added to the bleached plant samples, and the re-
  sulting mixture counted by LS.
  • The remaining  23-mL  fractions of methylene  chloride
  were placed into glass centrifuge tubes with 10 mL NaOH
  (pH 9), shaken for 2 min, and centrifuged for 4 min at 1000
  rpm (300Xg). The methylene chloride was discarded. The
  NaOH was acidified with 2 M Hd to pH<2 and extracted
  with 2 mL methylene chloride. The acid fractions were ex-
 tracted two more times with 2 mL methylene chloride. All
 extracts were combined in one vial and evaporated to dry-
 ness with N2 gas.
   Extract residues were derivatized for GC/MS (MS Model
 HP5970, connected to a GC Model HP5890) analysis by
 heating at 70 °C  for  15 min  with 20 nL  N,O-
 bis(trimethylsilyl)-trifluoroacetamide  (BSTFA)  (Poole,
 1978). Aliquots were injected on to a 0.32 mm :i.d by 25 m
 Ultra 2 column (Hewlett Packard, Boulder, CO) with a 0.52
 Mm film (Cross-linked 5% Phenol Methyl Silicons) at 150 °C.
 The oven temperature was ramped at 25 °C min-' to 280 °C,
 with a final hold time of 4 min. The detector temperature
 was 270 °C The helium carrier gas flow rate was  1.5 mL
 min"'.
   The mass spectra were recorded with the electron multi-
 plier at 1800 V and the ionization energy was preset at 70
 eV. Selective ion monitoring (SIM) at ion masses of 321,
 323,336, and 338 at 100 ms dwell times was used to analyze
 the extracts.
                    Calculations

  Total 14C estimates of plant uptake of PCP were based on
 I4C of dry combusted plant material. This I4C represents the
 maximum amount of PCP possible in the plant .is I4C-PCP,
 l4CMabeled metabolites, or "CO* Carbon-14 was detected
 in the control plants grown in soil containing no "C-PCP.
 The '^C in the control plants probably represented foliar
 assimilation of the I4CO2 released from pots containing I4C-
 treated soils.  This contamination was assumed uniform
across all treatments. Thus, "C contents for crops were re-
corded as net I4C (gross I4C dpm g-' in each treatment minus
 I4C dpm g-1 in the controls, mean — 300 dpm g- ')• Biocon-
centration factors (BCF) were calculated by dividing the net
 I4C (dpm g-1) in  the dry plant material by the initial "C
(dpm g-') in the dry soiL

-------
  600
                              J. ENVIRON. QUAL, VOL 19, JULY-SEPTEMBER 1990
         RESULTS AND DISCUSSION

        Carbon-14 Concentration in Plants

  Analysis of plant tissue by combustion (total
suggested uptake of "C-PCP (Beffin, 1989)
mation of mtact PCP in the plant tissue, S
necessary due to possible "C-PCP degradation
detection of '^-labeled metabolites.
                                            14O
        i                     rom   m
  the highest combustion "C contents, The«'C i
  methylene chloride extract represents PCP
  cWonnated phenols, and anisols (CasteSne el
                               —— —— —uwM^yicnc
                        , -,  —i significantly less








     PentacUorophenoI Concentration in Plants
                          ett»ct»' ^A *e high-
           n, were analyzed bv GC/VfS «nwn%«
identify only intact PCP. TrWamounteofLgSpCP
were detected in the fescue and fettucT NoPCT^S







     ™1
              &
              m
                   1.00
                  6.75
                aso
                                                ground tissue. The ^centratio? of^PTP ?^T












                                                           Bioconcentration Factors
                                 O.25
                                              aso
                                                            0.75
                                                                         1.00
                                     Organic' Carbon Content
                               t™™^™^^,^*^^^^^^^^^^

-------

-------
                          BELLIN & O'CONNOR: PUNT UPTAKE OF PENTACHLOROPHENOL
                                                                                      601
  the change in BCF values, calculated from 14C in meth-
  ylene chloride extracts. This effect was even more ap-
  parent when BCFs were calculated from actual PCP
  concentration, as determined by GC/MS SIM analysis
  of the methylene chloride extracts.
    The BCFs for fescue, carrot, and chile (Table 1) were
  calculated from total 14C determined by combustion,
  14C in  the-methylene chloride extracts,  and GC/MS
  measurements. The BCFs calculated from total 14C
  determined by combustion were maximum BCF val-
  ues representing l4Cas PCP, PCP-metabolites, and any
  other compound containing I4C. The BCFs from I4C
  in the methylene chloride extracts (representing PCP,
  lower chlorinated phenols, and anisols) were substan-
  tially lower. The BCFs based on GC/MS analysis (ac-
  tual PCP) were less than 0.01 for all crops. The PCP
  was not detected in the carrot peels or tops. The ex-
  tracted radioactivity in chile samples was only 5% of
  the total (combustion) radioactivity. Thus, due to al-
  ready low BCFs based on |*C in the methylene chloride
  extracts, chile (foliage and fruit) was not analyzed by
  GC/MS.
    The BCFs based on actual  PCP suggest minim?!
  plant uptake in any sludge or PCP rate treatment This
  was likely caused by rapid degradation of PCP in the
  soils.                          •
    Topp et aL (1986) reported PCP concentration fac-
  tors (fresh plant weight/air dry soil) for barley (Hor-
  deum vulgare L.) of about 7 after 1 wk in a soil with
  a pH 6.4. This concentration factor, however, based
  on I4Q likely overestimated actual PCP accumulation.
  Topp et al. (1986) attributed the large bioconcentra-
  tion factors to rapid degradation and mineralization
  of PCP, followed by plant uptake of I4CO2.
   Casterline et al. (1985) reported BCF values (fresh
  plant  weight  and air dry soil) of »1.0  for spinach
  plants, soybean plants, and soybean roots, based on
 analysis by gas chromatography with an electron cap-
 ture detector. Thus, BCFs suggested significant PCP
                                         uptake and much greater uptake than measured here.
                                         Several factors may have  contributed to the greater
                                         bioconcentration factors. Soil analysis revealed a half-
                                         life of PCP of about 25 d  (whereas the PCP half-life
                                         in our soils was about 10 d). The relative average plant
                                         exposure increases with increasing half-life. Based on
                                         a 25- and 1 OK! PCP half-life the-relative average ex-
                                         posure would be 0.3 and 045, respectively, for a 100-
                                         d growing season (Ryan et aL, 1988). Thus, greater
                                         uptake would be expected with a longer PCP half-life
                                         Casterline et al. (1985) sterilized their soil to inten-
                                         tionally delay degradation. The low sou* pll (estimated
                                         to be  <5.5) may also  have reduced  the activity of
                                         microorganism responsible for  PCP degradation
                                         DeLauhe et aL (1983) reported maximal degradation;
                                         at pH 8, and decreasing degradation with increasing
                                         or decreasing pH. Additionally, PCP sorptipn (Bellin
                                         et aL,  1990) was greater in an acid soil than two al-
                                         kaline soils. Adsorbed PCP may be less available for
                                         degradation than solution PCP. Speitel et aL (1989)
                                         reported slower degradation when PCP was adsorbed
                                         to granular activated carbon than when PCP remained
                                         in solution. Therefore, slower degradation in the add
                                         soil due to increased sorption allowing longer PCP
                                        availability and thus, greater opportunity for plant up-



                                               SUMMARY AND CONCLUSIONS
                                          Detection of intact PCP by GC/MS in fescue and
                                        lettuce revealed minimal plant uptake of intact PCP
                                        The BCF values (plant dry  wL/initial soil concentra-
                                        tions) were <0.01 for fescue and lettuce. On a fresh-
                                        weight basis, BCF values were <0.001. Intact PCP was
                                        not detected in the carrot (foliage,  peel, or pulp) and
                                        chile plants (foliage or pods).
                                          The GC/MS analysis  of extracts of soil samples
                                        taken after each crop harvest suggested PCP degraded
                                        so rapidly in these soils that minimal plant contami-
 Table 1. Fescue, carrot. and chile bioconcentratjon factors based on initial gog concentration «nd dry plant weights.

                                                               Carott
                                                                                           Chile*
    Sludge
     rate
PCP
rate
                                                      Plant
                       Total}
                                                                         Peels
                  MeOf   GC/MS*
                                                  Total
                                                          Med
                                                                    Total
                                                                             Med
                                                                Plant
                                                                Total
                                                                Fruit
                                                                Total
    Mg/ha


     0

    22.5

    45
nig/kg
0.6
5.1
0.6
5.1
0.06
5.1
0.77
134
1.18
2.25
0.84
2.18
0.08
0.14
0.08
0.08
0.06
0.10
  -tt
0.0072

0.0001
Bfaepoint toil

    0.06
    1.09
    0.04
    OJ3
    0.03
    0.28

Gleodafesoil
0.06

0.02

0.04
1.22
0.48
1.34
OJS
1-32
0.33
                   0.46
0.24
0.40
0.23
0.29
0.17
0.19
0.08
0.13
0.06
0.15
0.06
0.09
0
22.5
45
0.6
5.1
0.6
5.1
0.6
5.J
1.32
0.96
0.61
0.60
0-24
0.86
0.12
0.06
0.06
0.02
<0.00004
0.41
O22
0.45
0.10
0.20
0.13
0.03
0.01
0.01
1.71
0.27
2.09
0.37
1.63
0.42
0.13
0.08
0.16
0.07
0.09
0.09
0.15
0.16
0.09
0.07
0.17
0.27
0.05
0.00
0.03
0.03
'0.07
 —.-»...v wimwuMrMUMUUH TXJUCft IUT OTZVI PCCIS WCTC < 0.000 I
 Mea bioconcentration &aors for chife plant and {rat were 
-------
 602
J. ENVIRON. QUAU, VOL. 19, JULY-SEPTEMBER 1990
 nation could occur in the field. Thus, given normal
 application rates of sludge with normal (or even ab-
 nprmally high) PCP  concentrations,  concerns  about
 food chain plant uptake of PCP should not limit land
 application of sludge in these soils. This conclusion is
 likely appropriate to other high (>6.5) pH soils. How-
 ever, fUrther study is necessary to determine the bioa-
 vailabllity  of PCP in sludge-amended, low-pH soils,
 particularly those with high organic C contents where
 PCP half-lives are reportedly much longer (Bellin et
 aL, 1990).
                    REFERENCES

 Banerji, S.K., K. Piottfc, and J.T. O'Connor.  1986. Pentachloro-
  phenol adsorption on soils and its potential for migration into
  eroundwater. Hazardous and industrial solid waste testing and
  disposal VpL 6. ASTM STP 933. p. 120-139. Am. Soc. for Testing
  and Materials. Philadelphia, PA.
 Bellin, GA. 1989. Plant uptake of pentachlorophenol in sludge
  amended soils. MS. thesis. New Mexico State Univ., Las Graces.
  NM.
 Bellin, CJ^, G.A. O'Connor, and Y. Jin. 1990. Sorption and deg-
  radation of pentacbloropbenol in sludge-amended soils. J. Envi-
  ron. QuaL 19:603-608 (ibis issue).
 Be venue. A, and H. P^ium, 1967. Pentachlorophenol: A discus-
  sion of its properties and its occurrence as a residue in human
  and animal tissues. Res. Rev. 19:83-134.
 Buhler, D.R., M.E Rassmusson, and US. Nakaue. -1973. Occur-
  rence of bexachlorobenzene and pentachlorophenol in sewage
  sludge and water. Environ. Sti. Techno!. 7:929-934.
Casterfine. J.L., N.M. Barnett, and Y. Ku. 198S. Uptake, translo-
  cau'on, and transformation of pentachlorophenol in soybean and
  spinach plants. Environ. Res. 37:101-118.
Crosby, D.G. 1980. Environmental chemistry of pentachlorophenol:
  A special report on pentachlorophenol in the environment p.
  1052-1080. In Commission on pesticide chemistry. Dep. of En-
  vironmental Toxicology, Univ. of California, Davis, CA.
DeLaune, R.D., R.P. Gambrell, and KS. Reddy. 1983. Bite of pen-
  uchtorophenol in  estuarine sediment  Environ. PolluL Ser. B
                            6:297-308.
                           Fahrig, R., CA. Nilsson, and C Rappe. 1978. Genetic activ.
                            chlorophenols and chlorophenoi impurities, p. 325-338. In \
                            Rao (ed.) PentachlorophenoL Plenum, New York.
                           Hamaker, J.W., and J.M. Thompson. 1972. Adsorption, p, 49-1	
                            In CA.L Goring and J.W. Hamaker (ed.) Organic chemicals in
                            the soil environment. Marcel Dekker, New York.
                           Jacobs, L.W., GA. O'Connor, M.R. Overcaslv MJ. Zabek, and P.
                            Rygwiecz. 1987. Effect of trace organic* in sewage sludges on soil-
                            plant systems and assessing their risk to humans, p. 101-143. In
                            AI_ Page et aL (ed.) Land application of sludge. Lewis Publishers,
                            Chelsea, ML
                           Kloskowski, R., I. Schuenert, W. Klein, and F. Korte. 1981. Lab-
                            oratory screening of distribution, conversion and mineralization
                            of chemicals in the soil-plant system and comparison to outdoor
                            experimental data. Chemosphere 10:1089-1100.
                           Lagas. P.  1988a. Sorption of chlorophenols in the soiL Chemosphere
                            17205-216.
                           Lagas, P.  1988b. Behavior of chlorophenols in soil p. 264-266. In
                           . AA. Orio (ed.) Environmental contamination, 3rd International
                            Conference. CEP Consultants Ltd., Edinbuiig, UK.
                          Poole, CF. 1978. Advances in silylation of organic compounds for
                            GC p.  152-200. In K. Blau and G.S.  King (ed.) Handbook of
                            derivatives for chronutography. Heydon- and Son, Ltd,. London.
                          Ryan, JA, RJvt Bell, J.M. Davidson, and GA, O'Connor. 1988.
                            Plant uptake of non-ionic organic chemicali from soils. Chemo-
                            sphere 17:2299—2323.
                          Schafer. W., and VL Sandermann, Jr. 1988. Metabolism of pentach-
                            lorophenol in cell suspension  cultures of wheat (7n/tcwm aesti-
                            vum L.). Tetrachlorocatechol as a primary metabolite. J. Aerie.
                            Food Chem. 36:370-377.
                          Scheel, D., W. Schafer, and H. Sandermann. Ir. 1984. Metabolism
                            of pentachlorophenol in cell suspension cultures of soybean (G/y-
                           cine max L.) and wheat (Triticum aestivum L.). General results
                           and isolation of lignin metabolites. J. Agnc.  Food Chem.
                            32:1237-1241.
                          Speitel, G.E. Jr., C Lu, M. Turakhia, and X. Zhu. 1989.  Biodeg-
                            radation of trace concentrations of substituted phenols in granular
                           activated carbon columns.  Environ. Sci. Technol. 23:68-74.
                          Topp, E, L Scheunert, A. Attar, and F. Korte. 1986. Factors affectii
                           the uptake of "C-labelled  organic chemicals from soil.
                           Environ. Safety 11:219-228.                             ._
                          U^. Environmental Protection Agency. 1979. Water related env?
                           ronmental fete of 129 priority pollutants. Vol. 1 and 2.  USEPA
                           Rep. 440/4-79-029b. NTIS, Springfield,  VA.

-------
                                     Reprinted from the Journal of Environmental Quality
                             Vol. 19. no. 3. July-September 1990. Copyright © 1990. ASA, CSSA. SSSA
                                       677 South Segoe Road. Madison. WI 53711 USA
                 Adsorption, Degradation, and Plant Availability of 2,4-Dinitrophenol
                                    in Sludge-Amended Calcareous Soils
                                    G. A. O'Connor,* J. R. Lujan, and Yan Jin
                       ABSTRACT
    2,4-Dinitrophenol (DNP) is a moderately weak acid that is ex-
  pected to be highly labile (teachable and plant available) in high-
  pH soils. The adsorption and degradation behavior of DNP in two
  sludge-amended, calcareous soils was determined and used to ex-
  plain DNP uptake by plants grown in the soils in the greenhouse.
  The DNP adsorption was minor in both soils and was only slightly
  affected by sludge. The DNP degradation was rapid in both soils
  and was unaffected by sludge. Thus, despite  limited soil adsorption,
  plant uptake of DNP was minor in all crops and plant parts owing
  to rapid soil DNP degradation. Even if a municipal sludge highly
  contaminated with DNP was identified (an unlikely occurrence), con-
  cerns over possible plant contamination should not limit sludge ap-
  plications to calcareous soils at agronomic rates. Rapid degradation
  will minimize opportunities for plant uptake of DNP from contam-
  inated soils or leaching of DNP to groundwater, given careful water
  management
     2,4-DiNiTROPHENOL (DNP) is an active compound
      of considerable phytotoxicity to both animals and
  plants (Shea et al., 1983). It occurs as a waste contam-
  inant originating from several industrial sources, and
  may occur as a  degradation product  of other com-
  pounds. Shea et al. (1983) reviewed the various bio-
  logical  activities  of DNP in plant-soil systems, and
  noted that DNP behavior is highly pH-dependent ow-
  ing to its weak acid character (pKa =  4.09). Adsorpr
  tion of DNP is favored by low soil pH, but degradation
  is favored by high soil pH. They cautioned that careful
  management  is necessary if DNP is a predominant
 component in land-applied waste materials.
   The purpose of this study was to determine DNP
 behavior in calcareous (high-pH) soils amended with
 municipal sewage sludge and to determine the extent
 to which DNP is available to food-chain crops grown
 in such soils.
   In  high-pH, calcareous  soils, DNP adsorption
 should be minimal and DNP should be readily avail-
 able to  plants (Shea et al., 1983; Ryan et al., 1988).
 Sludge additions to soils may, however,  increase DNP
 adsorption (Shea et al., 1983) and thereby reduce DNP
.plant availability. Studies of DNP uptake by plants
 from sludge-amended  soils have not been conducted.
 This study was intended to supply such information
 and to explain the uptake data in terms of DNP soil
 behavior..

           MATERIAL AND METHODS

  Adsorption, degradation, and  plant uptake studies were
conducted with two calcareous soils from New Mexico. The

All authors. Dep. of Agronomy and Horticulture, New Mexico State
Uni v  Las Graces, NM 88003. Journal Article no.  1491, Agric. Exp.
Stn New Mexico State Univ. Although financial support for this
study was Provided m part by Cooperative Agreement CR-812687-
02 with the USEPA, this report has not had USEPA's required peer
and policy review and does not necessarily reflect the views ofthe
agency. Received  1 Aug. 1989. 'Corresponding author.
Published in J. Environ. Qual. 19:587-593 (1990).
  Glendale clay loam [pH 8.0, 6.5 g organic C (OQ/kg, and
  132 g CaCOj/kg] is classified as a fine-silty, mixed thermic
  Typic Torrifluvent The Bluepoint sandy loam (pH 8.0, 1.2
  g OC/kg and 30 g CaCOj/kg) is classified as a mixed, thermic
  Typic Torripsamment  Surface  (0-15 cm) samples of both
  were air-dried and sieved (<2 mm) before use.
    Soils were amended with a secondary, anaerobically di-
  gested sewage sludge from Albuquerque, NM. Air-dried
  sludge was gamma-irradiated (i:57Cs, 10 kGy) to further re-
  duce pathogens. Sludge  was thoroughly mixed,  sieved (<2
  mm), and, stored in 30-L plastic containers for use  in all
  studies. A screen for priority pollutants (USEPA method
  625), utilizing a gas chromatograph with a flame ionization
  detector,  revealed no detectable  (1 mg/kg) DNP in  the
  sludge. Sludge rates included 0 and 45 Mg/ha equivalent (20
  g/kg).
                   Adsorption Study

    The batch equilibration technique was used at a soil/so-
  lution ratio of 10:11 (w/v). Initial DNP soil concentrations
  were 1.0, 10.0,  50.0, and 100.0 mg/kg. Each solution con-
  sisted of 10 mL of nonradioactive DNP of appropriate con-
  centration and 1 mL of I4C-DNP. The rates were chosen to
  cover a wide range of concentrations, including rates much
  higher than expected in normal municipal sludge-amended
  soils. The median concentration  of most organics in mu-
  nicipal sludges is <10 mg/kg.  Such sludges applied at ag-
  ronomic rates would result in DNP concentrations in soil-
  sludge mixtures of <0.1 mg/kg (Jacobs et al., 1987). Uni-
  formly ring-labeled MC-DNP (specific activity 1.89 BqAg,
  >99% purity, Sigma Chemical Company, St Louis, MO)
 was present in each flask at 2.442 dpm/kg soil (disintegra-
 tions per minute per kilogram). All DNP solutions were pre-
 pared in  10-3 M NaCl (as background electrolyte) adjusted
 to pH 8.0 with NaOH. This pH was chosen to match the
 soil initial pH values to reduce pH variations of soil solu-
 tions  that might otherwise occur with the different DNP
 (acid) concentrations.
   The suspensions were shaken  on a wrist-action shaker in
 the laboratory (22 °C) for 18 h. Such vigorous agitation pro-
 motes thorough mixing of the  solute-containing solution
 with soil, and normally promotes rapid attainment of ad-
 sorption equilibrium. A preliminary time study suggested
 that equilibrium was not attained  in 18 h. We nevertheless
 chose  18 h of shaking for convenience and to minimize deg-
 radation effects (see below) on the disappearance of DNP
 from solution. Extrapolation of a preliminary percent ad-
 sorbed vs. time curve  suggested adsorption equilibrium
 would require about 36 h and would yield an additional 5%
 adsorption.
  After shaking,  the suspension  pH of the lowest (LO) and
 highest (100.0 mg/kg) treatments  was measured. Suspen-
 sions were then centrifuged (900 X g) to separate superna-
 tants. An aliquot (0.5 mL) ofthe clear supernatant was added
 to scintillation cocktail and counted to 2 sigma percent error.
 An external standard  was used  to correct for'quenching.
 Counting efficiency was typically ~0.75.
  Mass of DNP adsorbed was calculated as the difference in
 mass of DNP originally added and that remaining after 18
h. Two soil-less blanks were included  for each soil to detect
DNP losses  from solution by  mechanisms other than ad-
sorption. The soil-less blanks consisted of 100 mg DNP/L.
                                                     587

-------
 588
J. ENVIRON. QUAU VOL. 19. JULY-SEPTEMBER 1990
                  Degradation Study

   The DNP degradation was measured  in a simple flow-
 through incubation system. Air under vacuum was first bub-
 bled through water to humidify the air and to minimize soil
 drying. The humid air was then drawn through the air space
 of a flask containing 60 g of soil amended with 0 or 45 Mg/
 ha (0.02 g/g) sludge. The DNP was added at 3.7 mg/kg, and
 consisted of reagent-grade DNP plus 18.5 kBq I4C-DNP/
 flask. Carbon dioxide (including "COj) was trapped in a final
 test tube  containing 1 M NaOH. Soils were moistened  to
 water contents representative of moisture conditions-main-
 tained in the greenhouse study of DNP plant uptake (see
 below). The moisture contents (0.16 kg/kg for the Bluepoint
 sandy loam and 0.38 kg/kg for the Glendale clay loam) were
 slightly greater than  field capacity. A total of 14 flasks for
 each soil-sludge mixture allowed duplicate sampling at 0, 1,
 2,4,8, 16, and 32 d. (Preliminary studies suggested most of
 the DNP would degrade between 2 and 16 d, and that vol-
 atilization losses  of DNP were negligible.) Flasks were re-
 moved from the  train at appropriate times, and soils were
 immediately extracted with a mixture of 30 mL methanol
 and 30 mL 0.1 M Nad. The suspensions were shaken 3  h,
 and then centrifuged (900 X g) for 30 min to separate equi-
 librium solutions. The supernatants were transferred to glass
 bottles, pne-milliliter aliquots were removed for I4C assay;
 the remainder was refrigerated for subsequent high pressure
 liquid chromatography (HPLQ. analysis. Approximately 1
 mL of each supernatant was centrifuged (12-680 X g) for 2
 min to  further dear the samples. Aliquots (25 to 250 pL,
 depending on DNP concentration) were injected for HPLC
 analysis.
   The HPLC conditions were: RP-18 column, 4.6  X 250
 mm, mobile phase, methanol: 1 % acetic acid at pH 2.8 (50:50
 v/v), flow rate  1  mL/min. Under these conditions, the re-
 tention time  was  8.4 to 8.8 min. Detector UV at 254 mm,
•limit of detection was equivalent to 0.0174 mg DNPAg soil
 dry weight (~0.5% of initial).
   Extracted soil was air-dried and ground (mortar and pes-
 tle) for combustion.  About 300 mg  soil  was weighed into
 ceramic boats, covered with catalyst (activated alumina/cu-
 pric oxide powder, 5:1 w/w), and combusted at 1000 °C for
 8 min in an oxygen stream of 150 mL/min. Evolved "CO2
 was trapped  in a  mixture of 10 mL ethanolamine-ethoxy-
 ethanol (2:3,  v/v) and counted by liquid scintillation. Com-
 bustion efficiencies were typically ~95%. Samples  corre-
 sponding to Day 0 and 1 were combusted to determine mass
 balance and  extraction  efficiency. Mass  balance  (I4C ex-
 tracted 4- MC remaining in soil) averaged 101% across soils
 for times Day 0 and 1. Extraction efficiencies averaged 65%
 (SD - 3.9%) for  the Glendale soil and 69% (SD - 7.7%) .
 for the Bluepoint  soil, with no sludge effect in either soil. A
 preliminary incubation study utilized alcohol (95% MeOH)
 as the extractant (Overcash et al., 1982), but yielded extrac-
 tion efficiencies that  varied from 91  to 52% depending on
 soil and sludge treatment, even over  short (I d) times. Ov-
 ercash et al. (1982) also reported that the alcohol extraction
 efficiency varied (80-120%) with DNP concentration. The
 mixture of MeOH and NaCl used in  this  study seems pref-
 erable to alcohol  alone. The extraction efficiency was less
 than ideal, but was reproducible, and similar for both soils.


                  Greenhouse Study

  Sludge, soils (2 kg), and 2 g of fertilizer (18-48-0; 18-21-
 0, N-P-K) were thoroughly mixed in a blender. Fertilizer
 additions were intended to equalize  fertility differences of
 soils and sludge treatments.
  Six DNP rates (0. 0.1, 0.5, 1.0, 5.0,  and  10.0 mg/kg) were
 imposed on the soil and sludge treatments. The rates were
 chosen to avoid possible phytotoxic (>20 mg DNP/kg) ef-
                         fects on the crops (Overcash et al., 1982) and to cncompa
                         both reasonable and excessively high DNP rates expec
                         from additions of sludge containing priority pollutants
                         concentrations <10 mg/kg (Jacobs et al.. 1987).
                           The 24 treatments (six DNP rates, two sludge rates, two
                         soils) per crop were replicated twice. The decision to invest
                        ' in several DNP rates rather than more replicates was made
                         to detect the nature of plant response trends; with DNP rate
                         more precisely than with fewer DNP rates and more repli-
                         cates. With the same total number of pots, the estimate of
                         variance is the same, but the precision of the estimate of the
                         mean response is better with more DNP rates than with more
                         replicates; Each DNP treatment, except the control, con-
                         sisted of nonradioactiye, reagent-grade DNP plus uniformly
                         ring-labeled  I4C-DNP (specific activity 1.89 Bq/kg, >99%
                         purity; Sigma Chemical  Company, St. Louis, MO). The 0.1
                         mg/kg rate consisted of only 14C-DNP.  The amount of I4C
                         added to each pot was the same (11.100 dpm/kg, SD =- 10%).
                         Soil-sludge-fertilizer mixes were spread uniformly on a tray
                         covered with aluminum foil. The DNP solutions  (labeled
                         and uniabeled) were uniformly applied to  the soils with a
                         syringe.  The soils were mixed for several minutes by hand
                         and then transferred to  plastic pots. The mass of prepared
                         soil in each pot  was  1.8  kg. The excess soil  (200 g) was
                         retained for DNP analysis (see below) and for covering seeds.
                           Soils  were seeded  with fescue (Festuca arundinacea
                         Schreb., *KY 31'), carrot (Daucus carota L., 'Nantes'), lettuce
                         (Lactuca saliva L., 'Black Seeded Simpson'), and chile pep-
                         per  (Capsicum annuum L., 'Espanola' improved).  Seeds
                         were sprinkled uniformly on  the soil surface, and  covered
                         with a few millimeters of dry soil reserved from each pot.
                         After seeding, pots were  watered to pot-holding  capacity
                         (0.16 kg/kg for Bluepoint, 0.38 kg/kg for Glendale). Each
                         was then covered with newspaper to minimize evapora
                         during germination. Some leaching occurred from several
                         pots in  the initial watering, but leachate was collected  in
                         plastic saucers and was reapplied to the  respective pots.
                         Plants were watered approximately every 2 d to return them
                         to initial pot-holding weights. No subsequent drainage oc-
                         curred.       '
                           Fescue was grown for  32 d^ lettuce for 43 d, carrot for 70
                         d, and chile pepper for 90 d. Natural light was supplemented
                         as needed by eight 400-W sodium lamps to supply 16 h of
                         light Temperatures, in the greenhouse  varied  from 16 to
                         35 °C during the experiment.
                           Fescue, lettuce, and chile were harvested by cutting plants
                         about 3  cm above the soil surface. Carrot  plants were re-
                         moved with the main tap root intact Tops and roots were
                         separated with a razor blade and were washed with distilled
                         water until no visible soil particles remained. The roots were
                         then peeled, weighed, and stored  in paper bags. Peels were
                         also weighed and stored in bags. Plant fresh weight yields
                         were recorded immediately after harvest. All plant material
                         was then dried (50 °C) for a minimum of 12 h. Dried plant
                         material  was weighed, ground, and stored in'plastic bags for
                         later analysis.'
                          Soils retained from the initial  mixing and labeling with
                         "C-DNP and dried plant samples were assayed for MC  by
                         combustion as in  the degradation study. Approximately  50
                         mg plant tissue or 300 mg ground (mortar  and pestle) soil
                         was combusted.
                          Analysis of plant material for intact (parent  compound)
                         DNP was performed by an independent analytical firm using
                        approved USEPA extraction and  clean up procedures. De-
                        tection was by gas chromatography with flame ionization
                        detection. Given the limited mass of plant  tissue available
                        for extraction (~9 g, reps combined), the limit of detection
                        for DNP was 0.146 mg/kg.
                          Treatments were arranged in a random complete block
                        design. Analyses of variance were conducted for the varia-
                        b •;::  crop, plant parts, DNP rates, sludge  treatment, and

-------
                          O'CONNOR ET AL.: 2.4-DINITROPHENOL IN SLUDGE-AMENDED SOILS
                                                                                                      589
   bioconcentration factors based-pn MC. An LSD test was per-
   formed for variable means exhibiting significant differences
   in the analysis of variance.                    -


                Results and Discussion
                      Adsorption

    Adsorption data for the sludge-amended calcareous
   soils  are summarized in Table 1 along with  the pH
   values of the equilibrium suspensions measured. The
   pH values of intermediate DNP treatments  are as-
   sumed to be similar. The paste pH values of both soils
   in distilled water are 8.0. The lower pH values of the
   adsorption equilibrium suspensions are primarily
   caused by the background salt (IQ-3 M NaCl). rather
   than acidifying effect of the DNP. Sludge-amended soil
   pH values were consistently lower than unamended
   soil pH values, but the effect on adsorption was prob-
   ably minor. The pKa of DNP (4.09) is at least 2.6 units
   lower than the soil pH values, so <0.25% of the DNP
  exists as  undissociated acid in the most acidic treat-
  ment  (pH 6.7) and <0.14% at pH 7.0.
    The DNP adsorption was minor in both soils owing
  to their negative  charges and the dominance  of the
  anionic form of DNP. The Glendale soil.exhibited
  positive adsorption  (Freundlich K = 0.67 and 0.35.
  unamended and  amended, respectively) consistent
  with adsorption of other weak acid  organics 2  4-D
  and 2,4,5-T (O'Connor et al.,  1981) and pentachoro-
  phenol (Belliri et al., 1990) on this soil. Despite the
  soil's .negative charge, adsorption of weak acid com-
  pound occurs, and is  primarily associated with the
  organic fraction  (O'Connor  and  Anderson,  1974)
  Sludge additions slightly decreased DNP adsorption
  (Table 1), but had no effect on phenoxy herbicide ad-
  sorption by the Glendale soil (O'Connor et al,  1981)
   The DNP was repelled (negatively  adsorbed) from
  the Bluepomt soil at all DNP concentrations. This soil
  is extremely low m organic matter (1.2 g OC/kg) and
 apparently offered no positive adsorption sites. Sludge
 addition reduced DNP repulsion (Table  1), but DNP
 was negatively adsorbed in almost all treatments.
   Given the minimal adsorption of DNP in both soils
 in the presence and absence of sludge, DNP mobility
 is expected to be great. Careful  water management
 would  be  necessary  in DNP-contaminated soils to
 avoid groundwater pollution (Shea et al., 1983)  The   -
 DNP activity toward plants would be maximal in both
 soils and unaffected by sludge additions. Almost  all of
 the chemical would remain .in  solution available for
   plant uptake, or other removal processes  e g.  degra-
   dation and leaching.                     •«>•.&,


                     Degradation

    The DNP  degradation in the sludge-amended cal-
  careous soils (Fig. 1 and 2) is presented as percent DNP
  remaining (as determined by HPLC) plotted as a func-
  tion of time. The data have been corrected for ex-
  traction efficiencies. Similar plots (not presented) of
  percent MC  remaining in methanol/NaCI  extracts
  matched  closely the data in both figures. Thus  I4C
  extracted by  methanol/NaCI could have served'as a
  surrogate for  intact DNP, contrary to results we have
  obtained  for pentachlorophenol (Bellin et al  1990)
    A semilog plot of the data was used to identify first-
  order degradation kinetics. Neither soil, however
  demonstrated the single linear decrease in DNP re-
  maining with time consistent with simple  first-order
  kinetics. An initial linear decrease, lasting a few days
  was followed by  another linear decrease, of much
  greater slope, until only  a few percent of DNP re-
  ?lai™,^ls-J and 2)- Half-J'ves could be estimated
  for DNP  in both soils (~5 d in Glendale and ~9 d
  m-BIuepomtX but  are misleading. Much less DNP re-
  mains in the soils after 2  half-lives than the 25% ex-
  pected from first-order kinetics. A more meaningful
  description would  be that DNP has almost completely
  degraded in the Glendale soil in 8 d, and in the Blue-
  pomt soil m  16 d. There  was no significant effect of
 sludge on  DNP degradation in either soil.
   The DNP degradation in these soils was more rapid
 ^,^noted by other investigators. Overcash et  al
 (1982) reported 62 to 66% DNP loss after 4 wk in the
 acid Davidson clay loam [clayey, kaolinitic, thermic
 (oxidic) Rhodic Paieudults]. The USEPA (1979) re-
 P°rts a half-life of 50 d for DNP. Miller (1977) clas-
 sified phenolic compounds as slowly degradable. The
 DNP can be rather persistent in both soils and aquatic
 systems, but decomposition by certain strains of bac-
 tencide and by a fungus has been demonstrated (Shea
 et al.,  1983). The DNP  is bactericide at high concen-
 trations and low pH, thus, both these factors influ-
 enced toxicity and metabolism. The optimum pH for
 microbial decomposition (by reduction of the nitro
 groups to amino groups, followed by oxidative deam-
 ination, or by the release of a nitro group as nitrite)
 is near neutrality (Shea et al., 1983). Decomposition
 by release of NO2 by Corynebacterium simplex was
maximal at pH 8.0  (Gundersen and Jensen,  1956)
Treatment
DNP
mg/kg
1.0
10.0
50.0
100.0
Sludge
Mg/ha
0
45"
0
45
0
45
0
45
Ci
0.93
0.93
9.1
9.1
45.5
45.5 '
90.9
90.9
Glendale
Ce
-mg/L — — 	
0.54
0.70
6.9
7.4
39.1
41.1
82.6
87.5

mg/kg
0.43
0.26
2.5
2.0
7.2
4.6
9.5
3.9 .

PH
7.0 .
6.8
7.0
6.9

Ce
mg/L
1.01
0.93
9.7
9.3
50.5
47.3
99.2
95.9
Blueprint
x/m
fflg/kg
-0.09
0.00
-0.6
-0.2
' -5.6
-2.0
-3.2
-5.6

PH
7.1
6.9
7.2
6.7
t a - inin-a. concentration; Ce - equiHbrium concentration; */m - amoun« adsorbed per Uni, mass of soi!. AH valuei are ,he average of ,wo rep.ica.es.'

-------
 590
                                J. ENVIRON. QUAL.. VOL. 19. JULY-SEPTEMBER 1990
                                                        • Bluepoint  Soil
                                                                                        T
                       2   4   6   8  10  12  14  16  18  2O 22, 24  26 28  3O 32
                                                Time
	 : 	 1


 Fig, 2. The DNP degradation in Glendale soil (means ± I SD).

   Photochemical hydrolysis of DNP has not been
 demonstrated,  but has been suggested as possible
 (Shea et al., 1983). Flasks in our study, however, were
 wrapped with aluminum foil to exclude light, and
 there was no evidence of photolysis in the adsorption
 study (exposed containers).  Volatilization was also
 considered unlikely based on previous work (Overcash
 et al., 1982) and DNP's low Henry's constant (2.7 X
 10-«, dimensionless). Lack of volatilization was con-
firmed in a preliminary study with soil-less blanks;
Thus, the rapid dissipation of DNP in Our soils was
                                                    8
                                               Time(days)
                                                              1O
12
                                                                              14
                                                                                        16
                                                    attributed to microbial activity, favored by the initial
                                                    low (3.7 mg/kg) DNP concentration and high pH.
                                                     The rapid degradation of DNP in high pH soils has
                                                    important environmental  consequences. The essen-
                                                    tially complete degradation of DNP in 8 or 16 d (Glen-
                                                    dale and  Bluepoint, respectively) means that little
                                                    chemical remains in the soils long enough for signif-
                                                    icant plant uptake. Also, DNP is weakly, or negati vely
                                                    adsorbed in high-pH soils and could threaten ground-
                                                    water if the soils are leached excessively. Careful water
                                                    management that ensures chemical residence times of

-------
                             O'CONNOR ET AL.: 2,4-DlNITROPHENOL IN SLUDGE-AMENDED SOILS
                                                                                                           591
     Table 2. Effect of DNP and sludge.on yieldsf of crops in high pH soils in the greenhonse.
                                                                            Glendaie
Treatment
DNP
rag/kg
0
0.1
0.5
1
5
10
Sludge
Mg/ha
0
45
0
45
0
45
0
45
0
45
0
45
. Fescue :
Glendaie Bluepoint
2.60
3.80
3.45
4.70
4.50
4.00
4.60
4.20
4.35
4.30
3.15
3.65
•iiii ,
1.65
3.05
Z80
Z8S '
3.20
Z80
3.80
3.15
3.20
3.30
3.00
ZOO
Lettuce
4.55
4.00
5.50
5.90
. 5.65
4.25
S3S
6.00
3.55
5.55
5.15
4.65
Tops
, Carrot
Roots
	 g dr^ wt/pot — 	
4.30 2.45
4.15 1.80
3.85 1.15
4.10 0.85
4.85 2.60
4.40 1.20
4.80 2.25
4.95 1.10
5-50 1.70
6-15 1.55
5.60 2.00
4.15 MS
t Mean of two replicates. . " ' 	 ~ 	
Peels
	
1.30
0.80
0.75
0.60
1.30
0.75
1.75
1.10
1.55'
0.95
1.50
0.75

Pl*nt
. 6.25
8.15
6.70
6.95
6.35
6J5
8.05
8.40
5.30
630
6.05
6.90
Chile
Fruit
1.35
1.75
Z25
1.55
1.65
Z85
4.90
4.20
Z3S
3.05
3.00
4.55
1
    Table 3. The DNP bioconcentrarion factorst (dry-wt. basis) based on "C and intact DNP analysis.
                        Fescue
                 Glendaie
                             Bluepoint
                                         Lettuce
DNP Sludge
rag/kg Mg/ba
0 0
45
0.1 0
45
0.5 0
45
1.0 0
. 45
5.0 0
45
10. 0
45
"C

_
:_
0.432
0.295
0.781
0.472
0.840
0.838
1.46
0.542
1.07
1.05
DNP



NP


0.068 
-------
 592
J. ENVIRON. QUAL.. VOL. 19, JULY-SEPTEMBER 1990
•Table 4. Various estimates of DNP bioconcentration ftctors (fresh-
  wt. basis) at the highest initial DNP soil concentration (10 mg/
  kg).	
                          Bioconcentration factor
Crop
Fescue (Gtendak)
Fescue (Bluepoinl)
Lettuce
Carrot tops
Peels
Roots
Chile foliage
Fruit
"C
0.21
0.64
0.034 '
0.01
0.003
0.000
0.012
0.001
DNP
<0.040
<0.045
 1) bioaccu-
mulation, whereas the BCFs for the other crops imply
much less (passive, BCFs < I) bioaccumulation.
   The BCFs calculated on the basis of I4C are common
in the literature, but are misleading as the I4C is as-
sumed to represent intact parent compound. If the I4C-
labeled compound degrades in soil or is metabolized
within the plant, I4C contents of plant tissue  falsely
describe parent compound contents. Some 14C was de-
tected  in the plant tissues from control treatments.
Because there was no MC in the control soils (and no
DNP volatilized in the degradation study), I4C in plant
tissue in the controls was regarded as I4CO2 released
from l4C-tagged  soils.  This contamination was  ac-
counted for by subtracting the average I4C content
(~0.300 dpm/kg, effective BCF = 0.027) of all con-
trols from the |4C content of each treatment. Never-
theless, net I4C contents of plants  may still represent
|4C species accumulated other than 14C-DNP. Degra-
dation of DNP was rapid in both  soils, being almost
complete in 8 d in the Glendale soil and 16 d in  the
Bluepoint soil. Thus, even before the plants germi-
nated (5-20 d after planting), significant reductions in
actual soil DNP concentrations occurred, especially in
the Glendale soil. Fescue germinated 5 d after seeding
and was harvested 32 d after seeding. The three food-
chain crops grew for longer times, but germinated
more slowly. Lettuce germinated  20 d  after seeding
and was harvested on Day 54; carrot germinated on
Day 12 and was harvested on Day 70; chile germinated
on Day 20 and was harvested on Day 90. Given these
growth characteristics, one would expect greatest con-
tamination in fescue, less in lettuce and carrot,  and
much less in chile. The MC-based BCFs in Table 3
generally reflect the expected trend.
  Evidence exists that DNP is metabolized within
plants (Berlin et al., 1971; Klepper, 1979). Thus, even
if intact '"C-DNP were accumulated by plants,  I4C
contents of harvested plant material would not be clear
evidence of DNP in tissue. That plant metabolism can
completely obviate meaningful  interpretations of
BCFs based on |4C was clearly demonstrated in studies
similar to this utilizing diethylhexyl phthalate (DEHP)
as the target chemical (Aranda et al., 1989). Based on
all of the above discussion,'it is clear that BCFs based
on  |4C represent very conservative, and probably er-
roneously high, values.
  Attempts to improve on the I4C data by analyzing
for intact DNP were disappointing. Because of limited
                       plant tissue, the limit of detection (LOD) for DNP in
                       extracted plant tissue was only  0.146 mg/kg dry
                       weight Replicates were combined to yield plant tissue
                       for analysis, but only 8 to 9 g dry tissue was obtained
                       (Table 2) resulting in the stated LOD. When less plant
                       tissue was available, the LOD, (per gram tissue) was
                       higher. Thus, BCFs calculated on the basis of detected,
                       intact DNP were limited to LOD values and usually
                       exceeded the BCFs based on I4C (Table 3). Exceptions
                       were  for the highest initial DNP treatments. (10  mg/
                       kg). Particularly for fescue grown  in Bluepoint  soil,
                       actual DNP analysis showed the uC-based BCFs to be
                       grossly in error.      .     .-.
                       ,  Various estimates of DNP bioconcentration factors
                       for each plant and plant part are given in Table 4. The
                       BCFs are expressed on a fresh-weight- basis, because
                       all of these plants would be consumed fresh. Data for
                       unamended and sludge-amended soils have been av-
                       eraged because there was no significant effect of sludge
                       on BCFs across all treatments. The BCFs are presented
                       for the highest DNP concentration (10 mg/kg) because
                       DNP accumulation is likely greatest  at this concen-
                       tration, and  because  DNP determinations of intact
                       parent compound are useful only for this DNP rate.
                       The last column represents our estimate of the likely
                       maximum BCFs. The values are the smaller (but more
                       reasonably accurate) than the BCFs based on I4C or
                       actual DNP determinations. Even this estimate is con-
                       servative as no intact DNP was  indicated in any GC
                       chromatogram. Further, our degradation data suggest
                       minimal DNP  existing in  the soils long enough for
                       plant uptake. Plant metabolisrn of even .the small
                       amounts of DNP accumulated could also occur.
                         All of the BCFs (Table 4) are  low, suggesting min-
                       imal plant contamination with DNP.  Contamination
                       is minor regardless" of sludge treatment, at DNP con-
                       centrations an order  of magnitude (or more)  higher
                       than  expected under  normal  conditions. Calcareous
                       soils  more  highly polluted (>20 mg/kg) with DNP
                       would likely result in plant phytotoxicities (Shea et al.,
                       1983). If the soils are acid, phytotoxicities-occur- at
                       lower DNP concentrations  (Simon, 1953).
                         Thus, even if a municipal sewage sludge highly con-
                       taminated with DNP was identified (an unlikely oc-
                       currence), concerns over possible plant contamination
                       should not limit sludge application  to calcareous soils
                       at agronomic rates. Degradation of DNP in these soils
                       would minimize the amount of chemical, available for
                       plant  uptake. Careful  water management for the  first
                       30 d or so following DNP additions to high pH soils
                       would also minimize the amount of chemical available
                       for leaching to groundwater.

                                    ACKNOWLEDGMENTS
                         The assistance of J. Aranda, L. Tinguely, and.C. Bellin in
                       the greenhouse study, of Dr. M. Southward in statistical anal-
                       ysis, and of J Aranda and Dr. W.  Mueller in performing the
                       HPLC analysis for DNP is gratefully acknowledged.

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                       Bellin. C.A.. G.A. O'Connor, and Jin Van. 1990. Sorption and deg-
                         radation'of pentachlorophenol in sludge-amended soils. J. Envi-

-------
                           O'CONNOR ET AI-: 2,4-DlNITROPHENOL IM SLUDGE-AMENDED SOILS
                                                         593
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Berlin, J., W. Barz, H. Harms, and K. Harder. 1971. Degradation
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Klepper, I~A., 1979. Effects of certain herbicides and their combi-
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   Chemosphere,  Vol.17,  No.12, pn 2299-2323,  1983         0045-6535/88  $3.00 +-.OO
   Printed in Great Britain                                .Pergamori Press nlq
                PLANT UPTAKE OF  NON-IONIC ORGANIC CHEKICALS 7ROM SOILS
              J.A.  Ryan1*, R.H.  Bell2, J.M.  Davidson3,  and G.A. O'Connor*
                               1.UEL, USEPA. Cincinnati, Ohio. *S268.
                         Z.Environaantal Ad»i»ory Unit, Univaraity of Liv«rpool, U.K.
                           ,  3.Univaraity of Florid*. Gainnvilla, Florid..
                          «.N«w Naxico Stata University, Laa Crjjeaa, Nw Naxico.
i                                         *v*iaMfei
    Mcthooblogias utiliiirw tiapl* propartia* of chaaricals - half-Ufa . log octanol-vatar partition coafficiant (log K ) and
  H«f»ry'« Lav constant (He) - art oavalopad to scraan organic chaaricals fcVpotantial plant mtaka?                °"
                                     XNTRODUCTIOM
     Early  in 1983,  the  American  Chemical Society's Chemical Abstract Service
  registered  its  6,000,000th chemical. The Toxic  Substance Control  Act Inventory
  list 63,000 chemical substances whose manufacture, processing and ultimate use
  for commercial  purposes has  occurred  in  the United  States since  January, 1975
  (TSCA inventory,  USEPA,  1985).  Additionally, the number  of synthetic organic
  chemicals used and disposed of by society is increasing at a  rate  of about 1000
  new chemicals per year,  (Loehr and Malina,  1986) .  Thi« endless supply of compounds
  together with the variety of -reactions they can undergo in the environment makes
  describing their environmental impact  exceptionally challenging.

     Of  the  possible  locations  for  the disposal  of  wastes  -  surface waters,'
  atmosphere or land the latter represents a common location for waste disposal as
  well as  an  opportunity  to manage wastes with minimal environmental  impact.  The
  object of the land  disposal practice is to degrade, immobilize, and/or transform
  the wastes  into beneficial, or at least non detrimental  constituents.  There  are
  over 200 industrial waste 3and treatment sites in the United States, and a  larger
  number of land treatment sites  for municipal wastewater and  sludge  (Loehr  and
  Malina,  1986).  Land disposal  of wastes has increased  during the past  decade  and
  is  projected to continue to increase in the future (Loehr and Malina,  1986).

     The study of organic chemicals in the soil environment has been dominated by
  agricultural chemicals   (e.g.,  insecticides,  nematicides and herbicides)  and
 specific compounds that  persist  in the soil   (e.g., PCB's,  PBB's etc.). This
 narrow perspective  probably occurred because  of  the prevalence  of agricultural
 chemicals in soil,  complexity of  reactions, large number  of  compounds, and cost
 associated with organic analysis.  Specific  compound attention has been propagated
 by  the formation of  lists  of specific  compounds,  such  as the organic priority
 pollutant list o£  1976.  Even  with this narrowing of focus, the  cost associated
 with a  chemical by chemical  investigation is prohibitive.  The approach therefore
                                      2299

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 2300
 has been to utilize physicochemical parameters, or to group compounds on the'basis
 of their chemical or physical properties and study selected compounds from each
 group.  Clearly,  we must insure that the grouping of compounds is correct and that
 the factors used in the groupings predict the behavior and impact of compounds
 not studied.
    The following  attempts to  provide  a  frameworJc  which uses  physicochemical
 parameters to evaluate potential plant uptake of neutral or weakly ionized organic
 chemicals from  soil.  The  procedure does hot predict  plant concentration  of
 organics  in  a field situation, but provides a procedure  for  grouping chemicals
 by their  relative  potential for plant uptake.  As  such,  it should allow compound
 screening for  their  likelihood  for  plant  uptake  and, therefore,  justify
 experimental evaluation as well as identify chemicals of low concern where testing
 say be counterproductive.  It should also reveal where  information  is needed  to
 confirm the  screening model.
                         BEHAVIOR OF ORGANIC CHZKICAL*
    Many processes  impact organic chemicals in the soil environment.  The sum  of
 these  actions determine  the compounds environmental impact (Figure  1).  Factors
 such as pH,  CEC, OM content, clay content  and  soil water content all impact the
 rate  and  extent  of these  processes (Goring  and Hamaker,  1972).   In a  given
 situation (soil and environmental conditions)  however, the processes are dependant
 upon the physical  and  chemical properties of the, chemical. The  characteristics
 of  a chemical that determine its distribution between vapor,  solid,  liquid and"
 adsorbed phases in the soil, and its degradation rate become the characteristics
 that determine  its environmental fate and impact upon plants.  These processes
determine not only the fora of the compound that is present, but also the speed
at which the  compound moves or spreads through the soil  and atmosphere to achieve
its  impact.  The   importance  of .each of  these  .processes will be discussed
separately.
                   FIGURE  1
                                SOIL TRANSFORMATIONS

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                                                                             2301
  Degradation                   -   -
  •   Plant  uptake  of  most chemicals  is • concentration  dependent,  therefore  a
  compound's  persistence can alter its  ultimate fate and environmental impact.
  An  assessment of the half-life of a particular compound is  a.relatively simple
  way of limiting  the number  of soil  borne  organic ..compounds that need to be
  considered    as  likely to  impact  'a plant  grown  in  contaminated  soil.  The
  concentration of synthetic organic compounds.in  the 'soil  decrease with time,
  providing no further additions occur.'  Processes contributing to the decrease with
  tine are.biological and/or chemical degradation.  These processes  have been shown
  to  be  dependent  on -soil  and  environmental  'factors  (ie.,  temperature, water
  content,  soil pH,  and organic C), . (Hamaker, 1972).  Withput  the  quantitative
  information necessary .to describe the functional  dependence of degradation on
  these factors, it has been shown that  degradation of a  specific organic  chemical
  can be  described by  a first order rate  constant, p,  (Nash, 1980;  Rao and Davidson,
  1980; Jury  et al.,  1983; Gillett,1983). This  parameter is usually measured by
 determining the fraction of an applied  chemical remaining after a time t according
 to Equation 1 : .            .         '.        .'   '•
           M(t).= M(0) exp <~/*t>                                              C1]

 where M(t)  is the quantity of the compound remaining in the soil at time  t.  The
 half-life, T1/2, of a compound is defined as-the time required  for  one half  of  the
 concentration of the chemical  at any point in time to be lost  from the soil. This
 is  related  to the rate constant (ju)  by :                         .
          T/  -  Q-69?                        ,             .
            1/2 ~   M                      ,                        '        '   [2]
   Half-lives  of many chemicals have been published  (USEPA,  1979;  Jury  et al.,
 1983; .smith and  Dragun, 1984). Unfortunately,  reported values  of n may vary.
 enormously because measured half-lives of  compounds in  the  soil  do not always
 reflect degradation.  Often  losses  include other pathways (i.e., volatilization,
 leaching,  etc.).  Additionally,  water  content,  microbial  population,  and
 temperature  can significantly  influence the rate  of loss thus,  a  chemicals life
 r.ay vary from soil to soil. Half-lives are reported in Table 1 from data in USEPA,
 1979. compounds are distinguish from  one another on  the basis of half-life in the
 soil: less than 10 days, (Class A); between 10  and  50 days,  (Class B);.and  greater
 than 50  days,-(Class  C) . Gillett considered compounds of T1/2 greater than  14 days
 of sufficient stability to be  of concern (Gillett, 1983). The  impact of chemical
 half-lives on  concentration of  a  pollutant in the soil  over time is shown  in
 Figure 2.  Pollutants with half-lives  of less  than 10  days, for example,  are
 reduced  to less than  0.10% of their original concentration after 100 days in  the
 soil, m contrast; pollutants with half-lives of greater  than 50 days are  still
present  at >25% of their original  concentrations  after 100 days.  Their  impact,
and relative potential for plant uptake, are much more pronounced than that  for

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 2302
 compounds with half lives of less than  10 days.
            6-
            o
                                    HALF-TIME (days)
                                                 100
                           20
                                   40      60
                                   TIME (days)
                           80
                                  100
             FIGURE  2   EFFECT  OF  CHEMICAL ' HALF LIFE  AKD  TIHE  Oil
                        FRACTION  REMAIHIHG
   The  average concentration  present during the plant growing  period can  be
calculated by integration of Equation 1 between the limits 0 and t (growth, period)
and dividing by t. Assuming a  growth period (i.e. 50 or 100 days) the effect  of
half-life on the average soil concentration as a fraction of the amount originally
applied illustrates that the limits for classification of compounds based on half-
lives are arbitrary (Figure 3). The length of exposure  (i.e. plant  growth period)
and relative average exposure must be specified before compounds can be classified
by their half-lives.  For example,  our  use  of   10  and 50  day  half  lives  as'
classification end  points  was based  on  a 100 day  growth period and relative
average exposures of 0.15 and  0.5. Using  the same half-life end points but a  50
day growth period means relative average  exposures of  0.3  and 0.7.
                           20
                                     40        60
                                 HALF-LIFE (DAYS)
                                80
                                          100
             FIGURE   3
AVERAGE  SOIL  CONCENTRATION.  VS  HALF  LIFE
FOR  50  AND  100  DAYS  OF  GROWTH   -  '

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                                                                                                                   2303
    TABLE  l.   Log  K^;  Half-life  and  He  for  the  Priority  Pollutant*
t**r« log
  Caipaini

  PESTICIDES
  20.Acroltin
  22.Chtordv«
  24.006
  26.0i«ldrin
  28.Endrfn
  JO.K«pt»ehtor tpexidt
  32.lind*nt
  34.TO*

  MLTOUXIMATB «MOnS
  36i.Araditer  1016
  36c.Arodilor  1232
 3&t.Arochlor  1248
 36g.Aroehlor  1260
.!!!.?~.l!/?...!!!.

   -0.09   t   2.8E-03  21.Aldrin
   4.3 .   C   3.9E-03  23.000
   5.69   I   9.0E-04  25.00T

   4.5    C   1.7E-05  29.ltaptacnlor'
                                                                                                         4 ...04
                                                    ,
                                                 3.72

                                                                    3.lMp*Mron.
                                          3.SS
                                          5.9   *   *.2£.02
                                          3.8   t   3.0E.04
                                          1.70 , «J   nd
                                          3.85  c   2.1E.01
                                                 *.3B  C   8.61-01  36b.*roditor 1221
                                                 *-54  c   2.1E«00  36d.*rodiior 12*2
                                                 !1i  r   J'«"JJ  »*•*««*"«• «*
                                                 6.11  C   2.9E-01  37.2-chlom0itlMlm
                                         4.11
                                                       c   1.3E-02
                                                       C   5 SE-02
                                                «•<*   e   i:«-oT
                                                *.«   c   1.J£-02
 IALOKWTED AllPMTIC
 38.Chlora»tlunt               0.91   e
 40.TriehloroBtthant            .1.9    |
 42.Chlorb*thm                \ .54   |
 44.1,2-dtdiloriMtlww          1.48   •
 46.1.1,2-trietilerwtiwnt        2.17   nd
 48.Hcjuehlore*than»    '        4.62   nd
 50.1,1-dieiileratlMnt           1 48   A
 SZ.THehlerettiwnt              2.29   A
 54.1.2-dieMofOpfep«»          2;28   nd
 S6.N*iuehloretutadi«n»          3.74   e
 58.«roBMtlunt                 1.10   I
 60.DibranchleraBtthan*         2.09   nd
 62.0ichterodifluoraHthint       2.16   C

 •AUJGEJUTES ETKIS  •
64.1U(ehloroiithyl>«thw       -0.38   A
66.li«<2-ehtoroiMpropyl)*tlwr   2.M   nd
6S.*-chloroph«nyt ptMnytctlwr    4.08   nd
70.tt*(2-ehlore*thaxyXMthan»    1.26   C
                                                           1.6M1
                                                           1.2£-01
                                                           6.1t-01
                                                           3.8E-02
                                                           3.1E-01
              39.Dthyl
10).0f-n-propyl nitreuBin*
103.3.3-dichtoretanzidim
105.AcrylonitrU«
                                              Ml
                                                '
                                              0.06
                                              1.31

                                              fl'25
     .«E-03 95d.U0itiuil«nt
nd
nd

A
           nd
           nd
                                                                 SM.Ind»t123-aapxr«»
                                                100.0lph.vl nitrourint
                                                102.8«tidfn.
                                                10*'1'2-<»"ll*»lh»*«1'»
                                              4.07   C
                                              3.3T   e
                                              5.33   C
                                              s.6i   e
                                              6.84   C'

                                              4.04   C
                                              7.66   C
                                                                                     4.8E-03
                                                                                     2.0E-02
                                                                                     4.0E-04
                                                                                     4.1E-05
                                                                                      nd

                                                                                     4.9E-01
                                                                                      nd
2.57   nd  nd
i.gi   A   „,
3.03   nd  nd



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   2304
                   Partition
   ^  considerable research data exists on the equilibrium between an organic sorbed
  to  the soil and  that in the  soil-water phase. For  simplicity,  this  is  often
  expressed as a linear sorption isotherm (Karickoff, 1981):

  where Cs is the sorbed concentration (g/kg soil),  q is the solution concentration
  (g/m  soil solution)  and Kd  (m3/kg) is  the slope of the  sorption isother* or
  distribution coefficient  (Kay and  Elrick,  1967).  Equation  3  assumes  complete
  reversibility and equilibrium between the two pha.es, which may not  strictly occur
  for some  chemicals. Di Toro and Horzempa  (1982),  reported that  the sorptive
  process of 2,4,5,2-,4•,5'- hexachlorobiphenyl con.i.ted  of both reversible and
  strongly bound components, such bound residues could not be extracted by normal
  analytical techniques, but could be detected by radiolabelling. similar findings
  have been reported by others working with herbicides  and chlorobenzenes (Khan,
  1982; and Scheunert, et al., 1985) and may require the above mathematical approach
  for  sorption be modified to account for bound residuals.

    in soil, .and sediments, where the clay content is  relatively low,  pollufant
 sorption  occurs  primarily on the organic fraction of the .oil,   (Hamaker  and
 Thompson, 1972; Rao and Davidson, 1980). The degree of sorption of the non ionic
 organic pollutant is then dependant upon the organic carbon content in the soil
 or sediment. Variation between materials, which otherwise exhibit a wide range
 of physicochemical properties, can then be reduced by defining an organic carbon
 distribution coefficient (K^):
                 KKjj                                .    ,* ,
            __ "  _                   »
                 •foe                                                           [4]
 where Kd is the slope  of the  sorption  isotherm in ,Vkg,  and foe is the organic
 carbon fraction in the  soil or sediment, (Means, et al., 1982). This assumes that
 all organic matter has the same chemical structure.

    K   is defined as the ratio of the organic chemical  concentration in octanol
 to  that  in water, when  an aqueous solution of the organic chemical is mixed with
 n-octanol  and  then the organic chemical  allowed  to  partition between  the  two
 Phases  (Dawson,  et al.,  1980). There  have been  many  investigations  into  the
 relationship between  K,, and K^. Briggs (1973) for example'reported:
     iogK^ - 0.524  logK,,,, + 0.62
 from his work with  4  agricultural .oil. and 30 chemicals chosen  for  their wide
range of properties,  similar relationship., see Equation'. 6, 7, 8,  9,  and  10
have been reported ( Means, et al., 1982;  Schwarzenbach and  Westall,  1981; Rao'
«t al.,  1982;   Karickhoff, 1981; and Brown and Flagg, 1981 respectively).
     logK^ - logK^, -  0.317
                                                                             [6]
           - 0.721 lQgKM.+ 0.49

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                                                                              2305
        1(?9Koc ' 1-029 logK^, - 0.18
        logK,,. = 0.989 logK,,,, - 0.346     .                  .                    '
        logK^ - 0.937 logK^ -0.006               '  '"                        [1Q]
  The relationships are surprisingly similar to on. another considering they cover
  over 100 chemicals, as well as a large number of soils and sediments  (Figure 4)
  Thus when  the sorption value  of a particular pollutant in a particular soil is
  not available,  advantage can  be taken of the relationship between the organic
  carbon distribution coefficient (K^) and the octanol water partition coefficient
  (K^,) of the chemical. Recently, a nonempirical measurement (first-order molecular
  connective indexes)  calculated from the non-hydrogen part of the molecule ha. been
  shown to predict the KO- of organic compounds with great success (Sabljlc  1987)
  As these calculated values for various organic compound, become available it will
  allow for their use in place of K^ or
                                     log Kov
           FIGURE
                         RELATIONSHIP  BETVEEN   log   Koc  AND   log
    To  have greatest  impact upon plant uptake,  the organic compound must stay
 witlun the vicinity of the plant root, and not be  quickly Reached  away by mass
 flow. For example most residual .oil-acting herbicide, have Kd value, in the range
 of  1-20 with  value, up  to -40  being satifactory for  mo.t soil  applications
 (Graham-Bryce, 1984), compounds with *,-.  of gr.at.r tbmn 1000 becom. inactivated
 by  sou sorptxon  (Graham-Bryce,  1984). Ba.«J  on  Equation 4  and  Equation 9  for a
 son With ,„> 0.0125 (OM « at,- Kd's of l, 20, 40,  and 1000 would represent log
 K,,  s of 2.3, 3.6,  3.9, and  5.3,  respectively.
.   Vapor  phase partitioning of a compound in the ..oil influence, the spread of
the compound  through the  soil.  Even for  cheaical. with  relatively low vapor
          *hi" tranSPOrt rWt* h"  ^en *"«>  *° «- ^^ificant (Mayer,. t al.,
       Those chemxcals that have a high vapor pressure may easily move from the
sou solution into the soil air phase, where they can  move throughout the soil

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 23O6
 and across the soil  surface. The vapor-phase say be taken up by the plant either
 through roots or by above ground portions of the plant.

    The compartmentalization of the compound between the soil solution and the air
 spaces in the soil is frequently described by Henry's Lav (Jury et al.,  1983) with
 the extent  of partitioning described by Henry's Constant  (He) . This  can  be
 calculated as:
      Henry's Constant (He)  -     1$^04P M                                   tll]
                where P « vapor pressure of pure solute in mm/Hg,
                      H - molecular weight of solute,
                      T « absolute temperature,  and
                      S - solubility in water ag/L

 (Thibodeaux, 1979) .  Henry's Constant may be expressed  in different units and vary
 by several orders of magnitude depending upon the source  of the original data.
 For example, estimated values for vinyl chloride of 2.3 X 10"2 to 6.39  ata ms/mol
 are reported  by Mackay  and Shiu  (1981)  and  Goldstein  (1982) ,  respectively.
 Experimentally determined He values are considered more reliable than  calculated
 values. Henry's Constant, dimensionless, for the priority pollutants is provided
 in Table  1.

    Comprehensive  studies have not been conducted to determine the He above which
 volatilization  plays an important  role in the transport  of a  chemical  in the
 atmosphere.  Thus, it is not possible to select a He above which transport in the
 soil will  occur primarily in the vapor phase. However, a  partition between the
 vapor  and aqueous  phases of  greater  than  10"*  is  normally  sufficient for  a
 chemical  to be a good  preemergence herbicide  (Graham-Bryce,  1984) . Jury et
 al.,(1984) utilized three  volatility categories with He values of 2.5 x 10"3, 2.5
 x  10"s  and 2,. 5 x 10*7. Gillett  (1983) utilized values  of 10"3 and 6 x 10'5  in his
 classification. Thus, the value of 10"*  may be a reasonable transition point for
 determining  when  vapor  diffusion  becomes important.  This would  mean that vapor
 diffusion  would  be  important  for all. PCB's and halogenated  aliphatics and
 unimportant  for  some of  the  monocyclic and  polycyclic aromatics  and  many
 pesticides.  Soil  sorption can  significantly  reduce  chemical ' volatilization
 (Fairbanks et al., 1987) thus,  the arbitrary value of 10"*  may  overestimate the
 importance of volatilization in high organic carbon soils. Jury et  al.,  (1983)
used He and  K^ to calculate volatilization flux from' soil.
                       PLANT CPTAJOt OT OROAHIC
   Chemical uptake by  plants is a complex process that may involve a  compound
specific  active processes,  and/or .a passive  process  in which  the  chemical
accompanies  the transpiration  water  through the plant.  If  the  former case
dominates,  a rigorous relationship,  between plant uptake  and  the chemicals

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                                                                             2307
  physicochemical parameters   may not  exist,  although some general guidelines may
  be expected. If uptake into the plant is a passive process, rigorous relationships
  should exist.

    It is generally accepted that there  are four main pathways by which a chemical
  in the soil can enter  a plant  (Topp et al., 1986). These ar«:
      .1. root uptake and subsequent translocation by the  transpiration stream,
      2. vegetative uptake of vapor from the surrounding  air,
      3. uptake by external  contamination of shoots by soil and dust,  followed
         by retention in the cuticle or penetration through it, and
      4. uptake and transport in oil  cells which  are found in oil containing
         plants like carrots and cress.

    The amount of an organic chemical found  in a  plant will be the sum total of"
 each of these transport routes minus metabolic losses. Their respective importance
 will depend upon the nature  of  the organic chemical, the  nature of the soil, and
 the environmental  conditions under which plant exposure  occurs.  Pathways 364
 are significant only in specific situations. Thus,  for the purpose of describing
 the general  case of plant uptake,  they can be discounted as major routes of plant
 contamination.   Most reported  instances of plant uptake of  soil-borne organic
-compounds  make  no attempt to discriminate between pathways 1 & 2. Therefore, the
 relative  importance of each pathway, under  different environmental conditions,
 has not been assessed  at present.
 Reet  Ootake  And Traaaloeatien                                                '
   Shone and Wood  (1.972)  investigated  the  absorption" and translocation  of the
 herbicide  simazine  by 6-day-old  barley  plants  in  solution  cultures.   The
 experiments  were either 24-  or 48-hour experiments conducted under different
 conditions  of  humidity, light  intensity, temperature,  and levels of metabolic
 inhibitors.  The relationship between simazine  transport  and  water uptake  was
described by a  transpiration stream concentration factor  (TSCF),  defined as:
     TSCF = t"?  ?imagine in shoots per mL water transnired
            ng  simazane per mL  of external solution
They found that water was taken up preferentially to simazine, because the  TSCF
was always  less than unity,  i.e., the  concentration of  simazine in the plant
shoots per mL of water  transpired never reached that in the external  solution.
There was no evidence of loss of or breakdown of the parent compound  during the
experiment. The concentration of simazine in the plant roots, on a fresh  weight
basis, however,  reached a value  greater than  unity  as  a result  of  physical
sorption of the herbicide to the root tissue.

   Evaluation of other  triazines led to  the conclusion that plant uptake was, in
general, a passive process because TSCF was less than unity, {Shone et al.,1973).

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 2308
 Plant uptake of 6 herbicides and a fungicide showed.that TSCF was  independent of
 concentration and less than unity for all except 2,4-D at pH 4.0 (Shone and Wood,
 1974). In the case of 2,4-D at pH 4.0,  plant uptake vac metabolically influenced.
 Briggs et al.,(1982) evaluated  plant uptake of 18 chemicals and  found that  the
 TSCF was less than unity for all chemicals  studied. They related the TSCF to  the
 octanol/water partition  coefficient (KM)  for the chemicals and  found  a bell
 shaped relationship  between TSCF and K^,, with a broad maximum around a K^  of 1.8.
 A Gaussin  curve  (Figure 5)  was  fitted to the data such  that:

      TSCF-O^e-"10^- l-™> /2-«]                                  [12]
 /The authors suggested that at K^, values below 1.8,  translocation is limited by
 the lipid membranes  in  the-root. At Revalues above 1.8, translocation is  limited
 by the rate of transport of the lipophilic chemical  from the plant root to the
 top of  the plant.  All the TSCF values were  below  unity,  suggesting 'passive
 chemical movement into the shoot with  the transpiration stream.( There  wa» no
 evidence that chemicals were taken up against a concentration gradient.
                   1.0-1
               FIGURE  5   RELATIONSHIP  BETVEEH  log  Kov  AKD  TRAHSPIRATIOH
                          STREAK COHCEHTRATIOH  FACTOR
   Shone and Hood (1974) proposed that the uptake of a chemical  into a plant root
could be described by a root concentration factor (RCF),  defined as:
     TJCP m  concentration  in root.fug/a fresh wt.)
            concentration  in external solution, (pg/mli)
Using radiolabelled  herbicides in solution culture with  barley seedlings, they
showed that the quantity of  the herbicide transported  to  the plant stems  (TSCF)
could not be  inferred  from the concentration  in the plant  roots  (RCF).  In
addition, although the RCF  of some of the tested herbicides exceeded unity, uptake
was not affected by  temperature. This, suggests the compounds  were retained by
physical sorption rather than  biochemically.

   When barley  seedlings were  transferred from  the herbicide  amended solution
culture to a herbicide  free  solution,  RCF decreased before  TSCF was affected by

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                                                                               2309
  the change  (Shone et  al.,  1974).  Thus lipophilic herbicides appear to penetrate
  the cortical  cells of  the root whereas  the lipophobic  herbicides are  largely
  confined to the free  cell  space in the root.

     Briggs et al., (1982) found that RCF was related to K,,,. Starting with  a value
  of less  than  unity  for  polar  compounds,  RCF increased  with  increasing l^,.
  Sorption of chemicals by macerated roots  was very closely related  to the RCF of
  living roots,  for the more lipophilic chemicals. In contrast, the RCF of macerated
  roots  continued to decrease as the lipophilicity decreased  (Figure  6). There was
  a  linear relationship  between the log concentration factor of the macerated roots
  and log K,,,:
                  * root)  -' 0.77. logK,, - 1.52                                   [13]
                100
                                              MACERATED  ROOT
                        .  -0    •  -1 '      2       3    '   4      5
                                      log Xov
              FIGURE  6   EFFECT  OF  TISSUE' STATUS  OH  THE  RELATIONSHIP
                         BETVEEH  log Kov  AND  ROOT  COHCEHTRAT10H  FACTOR
             	*OB0t»a  from eriggs  «t Ol .  1982
    Assuming that RCF of living  roots  could be explained by two processes:  (1)  a
 partitioning of  the organic chemical  between the  lipophilic root  tissue and
 external solution culture  and (2)  a fraction of root  that is aqueous and  equal
 in concentration to external  solution phase (constant for all compounds, 0.82).
 Briggs et al.,  (19«3)  suggested that  sorption  of chemicals  by the  root  is  a
 partitioning described by:
      log(RCF -  0.82) - 0.77 logK,,. - 1.52                                    [14]
 They  proposed an analogous stem concentration  factor (SCF) :
      SCF -    concentration in stm iua/a fr.MH wt.i
              concentration in external  solution  (ng/*L)
Macerated stems sorption of organic compounds was also related to the K,,, of the
compound:         '
logSCF(-,crlt-
                  .t-)
                        0.95
                                    - 2.05
                                                                             [15]
Assuming that the  contribution of the aqueous phase in the stem was similar to
that in roots (0.82),  the partition between the stem and xylem stream is:  •
               ll-Mp) - 0.8,2) - 0.95  logK., - 2.05                            [16}

-------
   2310
   The SCF 'is then given by the K(,t-/xyli-Mp)  partition co*fficient multiplied by th«
   partition of the external solution present in the xylem sap  (TSCF) :
        SCF - [10(0.951ogKa, - 2.05)  +
                                                ~ 1.78)2/2.44)
                                                                               [17]
      For *5 chemicals (logK^ from -0.57 to  3.7),  th. .xp.rim.ntal point, fit th.
   predicted line quite well (Figure 7) . Th. shift, in log K,,, wh.re TSCF reaches a
   maximum (1.8)  to where  SCF reach., a maximum  (4.5)  ari... b«caus« sorption of
   the more  lipophilic compounds  by th. stra  tissu. incr.as.s faster than th. TSCF
   decreases. The predicted decline in see for compound, of log *  >  4.5  wa» not
   tested.                   '                             •     '
                FIGURE  7
                                                               8
                            RELATIONSHIP  BETVEEH  log  Kov  AND  PLANT
                            CONCENTRATION  FACTOR
    There have been other attempts to r.lat. plant upta*. and translation of an
 organic chemical to either the physical or  ch«ical prop.rti.s of th. chemical
 Topp et al., (1986) reported the relationship:
      logRCF - 0.63 logK,,, - 0.959         ,.               '.
 following their exposure of barley seedling, for 7-day, to various chemicals  in
 water culture.
    The concentration  factor  (CF)  concept is  a useful  way of  describing the
 relative  concentration of an organic chemical in a particular plant part, it has

 cZica?   vT', TVer>  ^  ari" "—»" *~ CmCmtration  °£ *****
 chemxcals,  both within th. soil or  nutri.nt  solution and within th. plant part
 mLT TTn C°nStant With tim*- Ch«aical« in «» «U. or in.nutri.nt solution,
 may be depleted by plant uptaJc. or degradation;  chemical,  in a plant may also be
 reduced with time  by degradation within th. plant, or by incr.as.s in plant mass
 effectively diluting the chemical, change, in upta*. a. measured by th. CF,  have
been reported, Figure 8 (Topp et al., 1986).  Different CF's aris. dep.nding upon
the timing  of th. actual sampling.  Further it  seem, logical that  the  CF would
depend upon soil concentration,  initial v. soil concentration at time  of plant

-------
                                                                                2311
  sampling.  Further research on this topic is needed to define the effect of time
  of  sampling  (both plant  and  soil)  on  CF'« so  different  experiments can be
  compared.
                     is  -i
                     10  -
                     5 -
                          BARLEY
                                      50
                                   TIKE  Cdays)
                                    100
                  FIGURE 8   EFFECT  OF PLAHT  TYPE AID LEBGTH  OF  GROWTH
                            PEROID  OH THE  PLAHT  COHCEHTRATION FACTOR
                            ««Bt«0 from TODD «  a I   19i6
    The work of Shone, Briggs, and their co-worker, reported above was carried out
 in nutrient  solution  cultures where   sorption and  desorption effects  of soil
 organic matter were absent. The application of their results to plant uptake from
 field soils requires that soil sorption be considered. The effect of soil sorption
 on son solution concentration can be mathematically described using the following
 relationship:       '                       •             _
            5CS
ec,
                                                                              [19]
 where CT  is the total organic chemical concentration in the soil (ng/g), S is the
 soil bulk density (g/cm3),  c$  is. the adsorbed chemical  concentration (Mg/g),  6 is
 the soil-water content by volume  (mX/cm5), and  C, i. the chemical  concentration
 in the soil-water phase (Ag/mL). Using the linear  equilibrium relationship  in
 Equation 3 and 4 allows Equation  19 to be rewritten in terms of c  such that-
    _c,.    =        s	
     CT      '      5Kpe^oc + S             .                 "            •         [20]
    It is  now  possible to   combine equations relating soil sorption and  soil
 solution  concentration and calculate RCF, TSCF, and SCF  for different chemicals
 on a total soil concentration basis.  Substituting Equation 20  into' Equation  17
 where CL is the external solution  and:
     SCF
        (SOIL)
gives:
concentration in
concentration in soil
     SCF,
        (SOIL)
                                                     5-2.44]
                                                                             [21],
   For nutrient solutions this equation reduces  to Eq 117] when /„,. -  o,  e - l,
and S =  i.  Inclusion  of  soil sorption  into the SCF  from Briggs et al.,

-------
 2312
 alters the relationship between  SCF and 109 K^ such that the log K^ where plant
 adsorption is a maximum decreases from 4.5 for nutrient solution to 1 for soils.
 (Figure 9).  The decrease  in  SCF for chemicals  with log  K^, greater than 1 is
 supported by the published literature on plant uptake in soil systems (Travin and
 Anus, 1988).
           bu
           U
           cn
               FIGURE  9   EFFECT OF  SOIL  ON  THE  RELATIONSHIP  BETWEEN
                           log  Row  AND  STEM  CONCENTRATION  FACTOR
   Equation 21 implies that plant uptake is related to soil organic natter content
 (Figure  10).Differences in the plant uptake of an organic chemical .in soils with
 different  organic carbon contents has been shown experimentally. Lichtenstein et
 al.,  (1967) for example,  showed higher concentrations of the pesticide aldrin in
 roots of peas when grown in  aldrin- polluted quartz sand compared to a loam soil
 containing approximately the same total concentration of the pollutant.
                     FIGURE  10  EFFECT OF  SOIL ORGANIC  HATTER  OH THE
                               RELATIONSHIP- BETVEER log Kow AHD
                               STEH  COHCEHTRATIOH  FACTOR
  •It is  also apparent  from Equation 21  that increases  in soil water  content
reduce SCF  (Figure  11).  However, for a soil with a fx of 0.0075  (1.25%  organic
Batter), changes  in soil water content over the  range  0.1 to 0.5 mL/cm3  altered
SCF less  than 10%  for chemicals with  a K^ greater than 2.5.  The fraction  in
solution,  (ecL/cT)j  increases as  soil  water content increases'  even though the
organic  chemical  concentration  (CL)   in  the soil 'solution-phase decreases.

-------
                                                                              2313
  Therefore, if plant transpiration were increased by increasing soil water content,
  plant  concentration  could   be  increased.  Walker,   (1971)   found  that  the
  phytotoxicities  of the  pesticides atrazine,  simazine,  linuron,  lenacil,  and
  aziprotryne were  increased as  the  moisture content of the soil increased.  He
  related the effect to differences in the quantities of  the  pesticides that were
  accumulated by the  plants,   with  the  degree  of accumulation  being  directly
  proportional to water uptake.                      :
                                        VOLUMETRIC VATER
                                        CONTEXT
                    -1
                                                           ,6'
             FIGURE 11  EFFECT OF  SOIL  VATER COHTEHT  OS  THE  RELATIONSHIP
            	BETVEEH log Kov AHD STEK COKCEffTRATIOS  FACTOR
    In conclusion,  assuming degradation of  the  organic chemical does  not occur
 within the plant,  and  plant root uptake and translation of  organic  chemicals
 from the soil is passive, plant uptake can be described as a series of consecutive
 partitions reactions. Partitioning occurs between soil solids and soil water  soil
 water and plant roots, plant roots  and transpiration  stream,  and  transpiration
 stream and plant  stem.  This partitioning can be related to the  K  of  organic
 compounds such  that pollutants with  high log *„,  values, (eg.  TCDD  (6.14),  PCB-S
 (4.12-6.11), some  of the phthalate esters (above 5.2) and the polycyclic aromatic
 hydrocarbons  (4.07-7.66))  are most likely to be .orbed, by the  soil and/or  plant
 root.  Chemicals with lower  KO- values are likely to be translocated within the
 Plant  and may reach significant concentrations/within the above ground portions
 of the plant.                         .           •                         •
 Vapor  Phase
   For volatile compounds, diffusion in the vapor phase and subsequent uptake by
the root  and/or shoot may be  an  important route of chemical  entry into plants
(Parker, 1966, and  Prendeville, 1968). Two processes precede the penetration of
chemicals in  the  soil into plant tissue  via the air: 1) volatilization of the
chemical from the  soil and 2) deposition from the air onto the plant surface. Soil
volatilization  depends  upon the  vapor pressure of the  compound which varies
according to ambient temperatures, water solubility of the compound, and sorption
capacity and physical properties of the soil.

-------
 2314
    Increasing the soil-water content of a  coil  will  increase the potential for
 volatilization  loss  of  a chemical   (Guenzi   and  Beard,  1970).  Harris  and
 Lichtenstein  (1961) showed that the rate of volatilization of aldrin from soil
 increased with aldrin concentration, soil moisture, relative humidity, temperature
 and the  rate of air  movement.  Chemical concentration  effects cease when the
 concentration reaches that required to give  a maximum saturation vapor  density
 equivalent to that of the pure compound. For dieldrin in  a  Gila silt loan soil
 this concentration was 25 ppm (Farmer et al., 1972). These  authors also rttport
 that under similar environmental  conditions the rate of volatilization was  lindane
 > dieldrin > DDT, which is the same order  for increasing  vapor pressures.  Jury
 et al.,  (1983 and  1984) developed a behavior  assessment model that  separates
 compounds into volatilization  categories based on Henry's  constants.

    There  have been  few investigations aimed   at  separating  root uptake  and
 translocation of a  chemical from vapor phase uptake into plant shoots. In  an
 experiment designed to discriminate these 'effects, Beall  and Mash  (1971)  found
 soybean shoots were  contaminated by soil applied dieldrin,  endrin and heptachlor
 largely via root uptake and subsequent translocation. Vapor phase .foliar sorption
 however dominated for DDT  and  was nearly 7  times greater than root sorption and
 translocation. Foliar contamination from vapor sorption of  residues from all four
 insecticides  was  similar (about 6.5 ppm plant dry weight),  whereas contamination
 from root sorption and translocation varied from 38 ppm  to 1 ppm depending upon
 the compound.        .   •

   Using  similar experimental techniques. Fries and Narrow  (1981) found that PCBs
 reached the shoots  of plants via the vapor phase rather than from  root  uptake,
 although  the  importance of this  route  for  PCS  contamination of plants  remains
 inconclusive.

   Topp et al., (1986) investigated the uptake of 16 organic chemicals  by barley
 seedlings. Foliar uptake was related to the amount of chemical  volatilized  from
 the soil  surface.. The  relationship (Figure  12) after 7 days  exposure was:
     FU - 46.11 + 28.95  log VOL                                             [22]
 where FU was foliar uptake  as percent of total UC uptake,  and VOL was the  organic
 UC trapped from the air plus that sublimated on the walls of the exposure  chamber-
 as percent of the total UC applied  (Note that  in the original publication the
 sign in  front of log  VOL  is negative, this is assumed to  be a typographical
error). Four  compounds (benzene, pentachlorophenol,  diethylhexylphthalate, and
the phenylenediamine pigment) did  not fit the calculated line because  they were
nonpersistent and taken up after mineralization  to 1*CO2.

   There  are  many  difficulties  in extrapolating  vapor  phase uptake  in the

-------
                                                                              2315.
  laboratory to that in the field. Overall, volatilization  rates are likely to be
  higher in the laboratory than in the field. This is because laboratory  soils are
  normally     kept   moist  to  encourage  plant  growth,   and  this   encourages
  volatilization. In addition, the actual deposition of volatilized chemicals onto
  a plant  in  the field is likely to be lower as  atmospheric  turbulence nay  be
  higher.
                    -2
                                 -i •       -o
                                    log VOLATILIZATION
                FIGURE  12  RELATIONSHIP BETVEEH  VOLATILIZATION  AND
                           FOLIAR  UPTAKE MBCKM from T
-------
 2316
 phase, and can  be related to   the octanol vater. partition  coefficient of the
 compound. Subsequent translocation of the chemical from roots to shoots depends
 on the K^ of the  compound  and the transpiration rate of the plant.  Based on
 available data,  compounds with a log K,,, of approximately 4.5 are most likely to
 accumulate in the stem and leaf tissue of plants.

    In soil systems,  -there  is competition between  the plant  and soil  solids
 (organic  fraction)  for.the partitioning of organic* from solution. As the sorption
 of the compound  by the soil  organic phase increases,  the quantity available for
 plant uptake   decreases. Based upon these considerations compounds with log K^
 of 1 -2 are most likely to have significant transport  of the chemical  to  above
 ground plant  tissue produced in soil systems. If metabolism  of the compound  in
 the  roots is  significant,   even  compounds  with low log  K^'s  may  not  be
 translocated  (HcFarlen et  al., 1987). Compounds with high log K^ > 5.0 would not
 be expected to be present in above ground plant tissue if plant uptake is limited
 by soil solution.

    The potential for root or plant sorption of organic compounds  from  vapor  is
 dependent upon the vapor pressure  of the compound. Very few experiments on this
 route of  plant  contamination  have been conducted. Based  upon the movement  of
 herbicides in the soil, a Henry's constant of  10"* may be used as a  transition
 point between primary movement in solution and vapor phases. If it can be assumed
 that  vapor movement in the soil will result in vapor uptake  by the plant,  then
 those compounds  with He >10"* are potential candidates  for vapor phase uptake.

   ,superimposed  upon both  of these processes  is the half-life of the compound.
 If it is  short,  i.e.,  less than 10  days,  the chemical is  likely lost from the
 system before  it can be taken up by the plant.  Those compounds with long half
 lives, i.e.,  greater than 6 months  or greater than the growing  season of the
 plant, presist long enough to  impact plants.

   Applying these screening processes to the priority pollutants, listed in Table
 1,  reduces the number of chemicals  likely taken.up by plants.  For example, if
plant uptake and translocation without vaporization  is the pathway of concern,
tb* li*t  of 107  chemicals is  reduced  to 50- on the basis of half-life and K^,
 (Table 2). If vaporization  is of concern the list is reduced from 107 to 64 on
the basis of half-life and He,  (Table 3).

-------
                                                                                              2317
TABLE  2 Log  K^,  Half-life  and  He  for Priority  Pollutant*  which  ar*  subject  to
plant  uptake from  soil
                                   tcsr
                                         '1/2
                                              He
PESTICIDES
2Q.Acrel«in
27.Endo«uU«n
31 .Nwuchlorocyctohwim
33.1taphorent

-0.09
3.55
3.8
1.70

8
C
8
nd

2.8E-03
nd-
3.0E-04
nd

26.D'i«ldrin
SO.ftpucnlor (pOKldt

35.Teu*hinB

2.9
3.9
3.72
3.8S

e
c
c
c

3.0E-04
3.2E-OS
6.0E-04
2.1E-01
NLYC8LOKIMTE9 B1PK8ILS ' '
MUCEMTEB ALIMATIC ITDtOCNB
38.Chtoranthan*
40.Tridttor<»thint
42.Chlerotthm
44.1,2-dichlerMthm
46.1,1.2-tricnloratthm
. 56.N*uchlorotoutadf«n»
59.lrandichleroMthn
61.TribronMtnm»
63.TriehlorofluaraHth«tt
MLOGEMTB cms
6S.8U(2-c*ilero*thyl)tth*r
70.8f(C2-dilorMtnexyMitam
mocraic AKMATICS
74. 1 ,3-dienlonbKuww
79.M1 tretenzanv
82.2,6-dinitretolum
86.2,4,6-tridilora^Mnpt
89.4-ni traphtnot
91 .2.4-diatthylpiwnol
93.4,6-dinitre-e-ermol
UK
0.91
1.9
1.54
1.48
2.17
3.74
1.88
2.30
2.53

1.58
1.26

2.84
3.55
1.85
2.05
3.61
1.91
2.50
2.85

C
8
8
8
nd

nd
nd
nd

nd
C

nd
nd
c
. nd
nd
.8
nd
nd

1.6E*01
1.21-01
6.1E-01
3.8E-02
3.1E-01
4.3E-01
nd
2.4E-02
2.4t*OO

4.7E-05
1. It-OS

1.5E-01
1.1E-01
5.4E-04
1.3E-02
1.7E-04
2.«E-04
7.SE-04
nd

39.0
-------
 2318
 TABLE 3.  Log K^,  Half-life and He for the Priority Pollutants which are subject
 to plant  uptake via volatilization
Cc*x»d 1
PESTICIDES
20.Acrol«in
23.BOO
27.Endc«ulfan
33.1tophorent
35.Teuph«nt
HLTOaOtlMTED 8IPKUIU
36».Arochtor 1016
36c.Arochler 1232
56«.Anxhlor 1248
36e.*ra»ler 1260
UUCEMTO ALIPMTIC ITOCCCMtl
40.TriehlortMt)un*
42.CMerotthan*
44.1,2-dtchlorotthm
46.1.1.2-trfchlerocthww
54 . 1 ,2-dfcJi toropropm
60 .0 i branch 1 ortacthm
62.0icnlorcdiftuoraMith«nt
KAUXSUTH) Eras
6A.li*(2-cMoroiMeraprl»tlMr
69.4-broKptMnyl ph«nyl «ttnr
KMOCTCLIC MOJMTICS
T2.Cntorct»nxm
74.1,3-dlchlerebtnun*
77. Muefl 1 enbtnztm
82.2,6-dlnitratolum
mmUUATE ESTEtS
KLTCTO.IC UCMTIC mCOCU«CB!
95c.Fluor«n*
97D.8*nze Oil f I uoranthm
97d.Chryunt
9Sc .6 1 b«ruo [t] tnthrietnt
"itmtwrr^w airuMn
101.DI-n-prapy( nltraUBin*
«**,
-0.09
5.99
3.55
1.70
3.85
4.38
4.54
5.6
6.11
OB*
0.91
1.9
1.54
1.48
2.17
2.28
1.10
2.09
2.16
2.58
4.28
2.84
3.55
6.18
2.05
3.22
C
4.13
4.18
6.57
5.61
7.23
5.97

0.06
1.31
T1/2
8
C
C
nd
C
C
• e
e
c
c
8
8
8
nd
nd
I
nd
C
nd
nd
nd
nd
C
nd
8
C
C
nd
C
C
C

nd
nd
He
2.8E-03
0.5E*00
nd
nd
2.1E-01
8.6E-01
2.1E*00
1.1E-01
2.9E-01
1.6E«01
1.2E-01
6.1E-01
3.8C-02
3.1E-01
1.2C-01
4.4E*00
nd
6.3E*01
4.7E-02
nd
1.5E-01
1.1E-01
7.0E-02
1.3E-02
1.9E-03
1. 06-02
4.8E-03
nd
8.8E-02
nd
nd

nd
nd
Ccapound
22.CMordm . -
25.DOT
31.N«aehleracycloh«iant ,
34.TCDO
36d.*radilor 1242 ,
36f.Arachter 1254
37.2-dilenraphtlwlm
41 .TctraehleroMthin*
43.1.1-dicMon»thm
45.1,1.1*triehlerattMra
56.ltaxKhlor«butid!m
61.TritaranBthin*
63.Tr
-------
                                                                            2319
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 Briggs,  G.G.  1973. A simple relationship between  soil adsorption  of organic
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 Briggs,   G.G.,   R.H.  Bromilow,  and A.A.  Evans.  1982.  Relationship  between
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 Briggs,  G.G., R.H. Bromilow,  A.A.  Evans,  and M. Williams.  1983.  Relationships
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 Briggs,  G.G..,  R.H.  Bromilow,- R. Edmondson, and  M. Johnston.  1976.  Distribution
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-------
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 Fairbanks,  B.C.,  G.A.   O'Connor,  and  S.E.  Smith.  1987.,  Mineralization and
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 Fries, G.F., and G.S.  Marrow.  1981. Chlorobiphenyl aoveaent from soil to soybean
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 (Received in Germany 11 September 1988;  accepted 4 October- 1988)

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