United States       Office of Water        April 1983
           Environmental Protection    Regulations and Standards (WH-553) EPA-440/4-85-022
           Agency          Washington DC 20460


           Water	
£EPA     Water-borne Routes of
           Human Exposure Through
           Food and Drinking Water

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                                     DISCLAIMER

This is a contractor's final report, which has been reviewed by the Monitoring and Data Support
Division, U.S. EPA. The contents do not necessarily  reflect the views and policies of the U.S.
Environmental  Protection Agency,  nor  does mention of trade names or commercial products
constitute endorsement or recommendation for use.

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REPORT DOCUMENTATION *• «PORT •«• *•
PAGE EPA-440/4-85-022
4. Tttto and Subtitle
Water-Borne Routes of Human Exposure through Food and
Drinking Water
7. Authors) Perwak, J.; Adamson, F.; Gilbert, D. ; Scow, K. ; and
Wallace, D.
9. Performing Organization Nam* and Address
Arthur D. Little, Inc.
20 Acorn Park
Cambridge, MA 02140
12. Sponsoring Organization Nam* and Address
Monitoring and Data Support Division
Office of Water Regulations and Standards
U.S. Environmental Protection Agency
Washington, B.C. 20460
3. Raclpianf s Accession No.
s. Raport Dat* Final Revision
April 1983
6.
8. Performing Organization Rapt. No.
10. Projact/Task/Work Unit No.
11. ContracttC) or Grant(G) No.
{0 C-68-01-3857
C-68-01-5949
(G)
13. Type of Raport & Parted Covered
Final
14.
15. Supplementary Not**
Extensive Bibliographies
 1ft. Abstract (Limit 200 words)
  This  report discusses  methods  for identifying  and  quantifying water-borne routes  of
  contamination  of human  food and drinking  water.  The  work was performed for  the  U.S.
  Environmental  Protection Agency (EPA)  as part of  a program  to  assess exposure/risk of
  65  classes of chemicals (129 "priority pollutants")  in the water  environment.   It  is
  intended  as a first  step in developing methods for  estimating levels of contaminants
  in  food  and drinking water  resulting from  water-borne  routes  of  migration.  Points of
  water contact  with food  in  growth stages,  processing,  and  preparation are  identified.
  A  simplified  methodology  is presented for  evaluating pollutant  intakes  during  the
  growth phase of crops,  livestock, poultry, and fish,  and information is presented  on
  water  use  in  food processing  and  home preparation.   The  routes  of contamination  of
  drinking  water during treatment and  distribution are  identified.
 17. Document Analysis  a. Descriptors
  Exposure
  Risk
  Water  Pollution
  Food Contamination
   b. htantMara/Opan-Eiwtod Terms
c. COSATI Reid/Group 06H 06T
IS. Availability Statement
Release to Public
19. Security Class (This Report)
Unclassified
20. Security Class (This Page)
Unclassified
21. No. of Pag**
60
22. Price
$10.00
SeaANS»-Z39.1»
                                       See Instructions en Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-3S)
Department of Commerce

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                                       EPA-440/4-85-022
                                       December 1981
                                       (Revised April 1983)
      WATER-BORNE ROUTES OF HUMAN EXPOSURE
        THROUGH FOOD AND DRINKING WATER
                      by
        Joanne Perwak,  Francis Adamson,
           Diane Gilbert,  Kate Scow,
              and Douglas  Wallace
            Arthur D. Little,  Inc.
        U.S. EPA Contracts 68-01-3857
                           68-01-5949
              Michael W. Slimak
               Project Manager
    U.S. Environmental Protection Agency
Monitoring and Data Support Division  (WR-553)
  Office of Water Regulations and Standards
           Washington, D.C.  20460
  OFFICE OF WATER REGULATIONS AND STANDARDS
               OFFICE OF WATER
     U.S.  ENVIRONMENTAL PROTECTION AGENCY
            WASHINGTON,  D.C.   20460

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I
I
                                          FOREWORD

                This  report  is  part  of  a  series  of  documents  prepared  under  the
           Monitoring and Data  Support  Division's pollutant exposure fate  and  risk
           assessment program.   This program  is  directed  towards  investigating the
           risks due  to  presence of  129 Priority Pollutants in our nation's  waters.

                Sone  of  the  reports  prepared  under  this program address  specific
           pollutants.   Others,  such as this  one, are generic in  nature  and  are meant
           to  be tools for use  when  performing risk assessments on a wide  variety of
           pollutants.

                This  report  investigates  pathways through which waterborne pollutants
           can enter  or  leave food during various phases of growth, harvesting,
           processing, and preparation.   It addresses the overall potential  signi-
           ficance of  these  pathways.

                A companion  report,  Identification  and Evaluation of Waterborne Routes
           of  Exposure from  Other than Food  and  Drinking  Water  (EPA-440/4-79-016),
           investigates  other means  of  exposure  to  waterborne pollutants:  inhalation
           of  vapors  from polluted waters, and dermal absorption.

                A related series  of  documents assesses the overall risks from  54 of
           the most important Priority  Pollutants.  These documents compare  the
           importance of all known exposure routes, environmental pathways,  and
           sources of the particular pollutants.

                                     Michael W. Slimak, Chief
                                     Exposure Assessment Section
                                     Monitoring &  Data Support Division (WH-553)
                                     Office of Water Regulations and Standards
                                            111

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                           TABLE OF CONTENTS



 LIST OF FIGURES

 LIST OF TABLES                                                     ix

 1.0  SUMMARY AND CONCLUSIONS                                       1_1

 2.0  INTRODUCTION                                                 2-1

 3.0  WATER-RELATED  CONTAMINATION OF FOOD  DURING GROWTH            3-1

 3.1  Food  Crops                                                   3_1
      3.1.1  Principles  of  Irrigation and  Crop  Physiology           3-1
             3.1.1.1  Irrigation                                   3-1
             3.1.1.2  Crop  Physiology                              3-5
      3.1.2  Contamination  Model                                   3-5
             3.1.2.1  Assumptions                                  3-9
             3.1.2.2  Sample Applications                           3-10
             3.1.2.3  Limitations of Model and  Comparison
                      of Model Results with  Monitoring  Data         3-12
 3.2  Livestock  and  Poultry                                         3-13
      3.2.1  Ingestion                                             3-13
      3.2.2  Dermal  Absorption                                      3-13
      3.2.3  Comparison of  Two Exposure Routes                      3-20
 3.3   Aquatic Organisms                                             3-20

 4.0  WATER-RELATED  CONTAMINATION OF FOOD DURING PROCESSING         4-1

 4.1   Introduction                 '                                 4_1
 4.2   Utilization of Water  in Food Processing                       4-1
      4.2.1   Introduction                                           4_1
      4.2.2  Meat Products                                          4.3
      4.2.3  Dairy Products                                         4_6
      4.2.4  Preserved Fruits and Vegetables                        4-6
      4.2.5  Grain Milling Products                                 4-8
      4.2.6  Bakery Products                                        4-9
      4.2.7  Sugar, Confectionery Products                          4-9
      4.2.8  Fats and Oils                                          4-10
      4.2.9  Beverages                                              4-10
     4.2.10 Miscellaneous Foods                                    4-11
     Summary  of Water Use During Processing                        4-11

5.0  WATER-RELATED CONTAMINATION OF FOOD DURING HOME
     PREPARATION                                                   5_!

6.0  DRINKING WATER CONTAMINATION DURING TREATMENT AND
     DISTRIBUTION                                                  6_]_

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                          TABLE OF CONTENTS (Continued)
6.1  Introduction                                                 6_1
6.2  Chemical Additions at the Treatment Plant                    6-1
6.3  Chemical Formations at the Treatment Plant                   6-1
6.4  Pipe Corrosion                                               6-3
     6.4.1  Metal Pipes                                           6-3
     6.4.2  Asbestos-Cement Pipes                                 6-5
     6.4.3  PVC Pipes         *                                    6-5
6.5  Accidental Contamination in the Distribution System          6-6
6.6  Summary                                                      6-6

7.0  REFERENCES                                                   7_1
                                vi

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I
                                         LIST  OF  FIGURES

              Figure  No.                                                        Page

                 3-1      Consumptive Use  of Water by  an Annual                   3-7
                         Plant During  Various  Periods  of  Growth

                 3-2      Influence of  Environmental Temperature  on               3-17
                         Feed Consumption, Heat Production,  and  Feed
                         Utilization in Dairy  Cattle

                 6-1      Sources of Contamination of  Drinking Water              6-2
                         in Treatment  and Distribution

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I
                                        LIST OF TABLES

            Table No.
                                                                             Page
              3-1     Common Water Capacities of Soil by Soil Types           3-3

              3-2     Seasonal Consumptive-Use Requirements of Common         3-4
                      Irrigated Crops in Relation to the Requirements
                      for Alfalfa—Western States

              3-3     Normal Crop Water Use.   Central Coastal Plains.         3-6
                      Evapotranspiration (Consumptive Use)  Table

              3-4     Symbols Used in Food Crop Contamination Model           3-8

              3-5     Comparison of Estimated and Measured  Cadmium            3-14
                      Residues  in Food Crops


              3-6     Average Daily Water  Consumption of Poultry and          3-15
                      Livestock


              3-7      Representative  Body  Surface Areas  and Weights           3-18
                      for Various  Livestock Species

              3-8      Estimates  of  Daily Water Absorption Through  Skin         3-19
                      of Various Livestock Species


              3-9      Regression Equations Correlating Bioconcentration        3-21
                      Factors (BCF) in Aquatic Species to Other Parameters

             4-1     Water Intake of Major U.S.  Industries, 1973              4-2

             4-2     Process Water Usage by U.S. Food Industry                4-4
                     Groups, 1973


             4-3     Water Requirements of Selected Canned  Products           4-7

             4-4     Direct Food/Water Contact During Processing by           4-12
                     Food  Industry Group


             5-1     Estimated  Water Use in Home Preparation  of  Food         5-2

             6-1     Metals  in  Drinking Water Resulting  from  Various         6-4
                     Types  of Plumbing


             6-2     Contamination of  Drinking  Water  in  Treatment             6-7
                     and Distribution

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                     1.0   SUMMARY  AND CONCLUSIONS
      The  Monitoring  and  Data  Support  Division,  U.S.  Environmental
 Protection  Agency,  is  investigating the  sources and  distribution of
 129  priority  pollutants  in  the  nation's  environment  in  order  to  iden-
 tify populations  of  humans  and  biota  exposed  to these pollutants and co
 determine the associated health risks.   In  support of that  effort,
 this task was undertaken to identify  and  quantify major water-borne
 routes  of human exposure through food and drinking water.

      Points of water contact  with food have been identified and,  to
 the  degree  possible, the timing and volume  estimated.   While  it  was  not
 possible  to arrive at  an overall methodology  for estimation of con-
 tamination, the available information on  the  extent  of  water  contact,
 especially  in growth,  processing and  preparation, suggests  that  this
 source  may  be an  important  route of exposure  to humans  and  livestock.

      A  simplified methodology has  been developed for  evaluating  pollutant
 intakes via the water-borne route  for food  in the growth phase,  in-
 cluding crops, livestock, poultry, and fish.  Background information
 on water  use  in food processing  and home  preparation  is presented that
 could form the basis for the development  of an  estimation model  in the
 future.   Several steps (some exceedingly  complex) are required before
 actual levels  of food  contamination resulting from water contact  can
 be estimated:

     •  Relate yield of crop to  total yield of biomass per acre
        for a better estimate of concentration;

     •  Quantify pollutant loss rates from food during the
        growth period;

     •  Quantify pollutant uptake and loss rates from food
        during processing and home preparation.

     However,  in the process of considering food contamination,  several
water-borne routes of contact were identified as being potentially impor-
tant, and could result  in human exposure to pollutants.

     •  crop growth —  rainfall or irrigation water

     •  water  consumption of livestock and poultry

     •  uptake of  pollutants from water  by aquatic  organisms

     •  water-mixing  with food products
                                 1-1

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     The relative importance of these routes cannot be established at
this time.  In addition, although food processing has been shown to
involve large quantities of water, the importance of this route cannot
be established since a detailed assessment of the surface area contacted
and the time of contact would be required.  This would vary by crop and
process step.

     The routes of contamination of drinking water in treatment and
distribution have also been identified.   However, a model predicting
concentrations in drinking water from these sources was not considered
feasible at this time.  It appears likely that only specific situations
of contamination (i.e., trihalomethane formation, or lead corrosion)
could be modeled due to the unique nature of each situation.
                                 1-2

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r
                                       2.0  INTRODUCTION
                 The Monitoring and Data Support Division, U.S. Environmental
            Protection Agency, is conducting a systematic investigation of the sources
            and distribution of 129 priority pollutants in the nation's environment
            in order to determine the exposure and risks to man, fish, and other
            biota.   One part of this program is the preparation of exposure and risk
            assessments, which identify the populations exposed to specific chemicals
            and estimate the health risks to man,  fish, and wildlife.   In the conduct
            of these risk assessments, it is important to identify and quantify the
            major water-borne routes of human exposure to pollutants.

                 This task considers methods for identifying and quantifying water-
            borne routes of human exposure.   The objectives of this task'were to:

                 •   Identify water-borne routes of contamination to food.

                 •   Identify routes of contamination in drinking water
                    treatment and distribution.

                 •   Develop a methodology for quantifying the contamination
                    of  food and drinking water through the routes identified.

                 The project was  focused primarily on the first two objectives;
            data  limitations meant  that  the  third  objective could be addressed  only
            in a  very preliminary fashion.   In addressing these objectives,  several
            simplifying assumptions were made:

                 •   The pathways  of  pollutants  to  the water compartments were
                    not considered.

                 •   The routes  of contamination  of  drinking water  supplies
                    were not  considered.

                 •   The quality of various sources  of  water used  in  food
                    production was not differentiated.

                 •   Pollutant losses occurring in any  phase  of  food  production
                    or  drinking water treatment and distribution were considered,
                    but not examined in  detail.

                This task was a first step in estimating inputs of  contaminants
           to food  and drinking water.  In order to estimate actual concentrations
           in food, losses would need to be considered, as well as  the specific
           characteristics of each type of food and pollutant.
                                              2-1

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      In  order  to  characterize  the  routes  of contamination of  food and
 drinking water, several  steps  in the  production  of  food  and drinks
 water were  examined.   For  food, Chapters  3.0,  4.0,  and 5.0 examine °
 contamination  during  growth, processing,  and home preparation.   Of
 these areas, contamination  during  growth  is the  one that can  be  charac-
 terized  most quantitatively at present.   A  simplified methodology is
 developed for  estimating water, and thus  pollutant  uptake fay  crops.
 Rates of water uptake  for livestock,  poultry,  fish  and shellfish'are
 also  discussed in Section 3.2.

      Chapter 4.0 describes  water use  in food processing.   It  identifies
 types of water contact and  estimated  volumes used in various  processes
 tor different rood groups.  Water  use in  home  preparation is  considered
 in a  similar manner in Chapter 5.0.   No attempt was made  to develop  a
methodology for estimating  pollutant  intake in processing  or  home
preparation, since a multifaceted model would be required, and the in-
formation presented in this report is only  the first step  in  the develop-
ment of such a methodology.

     The possible routes of contamination of water supplies during
treatment and distribution are considered in Chapter 6.0.  Due to°the
nature of the contamination routes, the development of a  general method-
ology tor estimating concentration  was not attempted.     S«^rax mecnoa
                                   2-2

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         3'°  WATER-RELATED CONTAMINATION OF FOOD DURING GROWTH
  3.1  FOOD CROPS
         Principles of Irrigation and Crop Physiology
  _   _  This section summarizes the key principles of crop phvsioloav and
  zrr^atxon practice as  background for constructing a preliminarv model
  ^or  food  crop  contamination by irrigation water.   In order to provide
  aa-™^ :  SlmPle rth°d  °f  aP?roximati^g uptake,  pollutant ur>take is
  Su TIL  r*  ^  Wlth WatSr UPtak£'  alth°ugh  this  is  often not the case.
  Thus, tne  resulting  model  is not  an  exhaustive  theoretical  model incor-
  porating  all pnysical and biological  processes  but  rather  a simplified
  metnod o,  approximating uptake.   Its  purpose is to  determine the  imoor-
  tance of water-borne routes  of contamination during  crop c,rowth
 3.1.1.1  Irrigation
      Optimum plant performance results at least partiallv  from an uninter-
 rupted and adequate supply of water  (Janick et al. 1969)'.  The nature
 of each agriculture site is defined by many factors, including soil
 horizons, weather regimes, topography, and groundwater hydrologv
 Because of the inherently wide variation in and numerous possible com-
 binations or these factors, irrigation guidelines have been developed
 experimentally for specific crops and soil types in various regions of
 the t.S.^ The state Extension Services can supply irrigation data, cal-
 culated ror the specific weather condition being experienced in the
 region.  As an aid to agriculturalists,  the Extension Services also
 r_ ,       kfdS  °f  w«er are associated with soil:   hygroscopic,  gravi-
 tational  and  capillary.   Hygroscopic water is the thin film of water
 tightly bound to  the  soil particles.   This bonding  renders the water
 unavailable _ to plants.   Capillary water fills the spaces  between  soil
 ?^tlCr6?' 1S f"  ln PlaCe  by WSak  molec^r forces,  and is available
 for uptake oy plant roots.   The  third type of water associaTed with soil
 is gravitational.   This  is the water  that  will be drained by gravity down
 to the water  table  or to  an  impervious  sublayer once the  spacfs between
 the soil particles have  been  filled by  capillary  water.   The "field
 capacity  of  a given  soil type is defined  as  the  volume of  capillarv
 hf-             follwin§ the Drainage of gravitational water.  When
the field capacity _ is used up by withdrawal by roots or by evaporation,
the wilting point is reached and plants loose their turgor (the swollen
condition of the cell caused by internal water pressure).  Since It inter-
rupts the plants' normal physiologic functioning (Janick et al. 1969)
loss of turgor is generally avoided.                     --
                                   3-1

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     Moisture is added to the soil by precipitation and irrigation.  The
 effectiveness of precipitation is a function of the intensity and dura-
 tion of the storm, the air temperature, and the soil absorption capacity
 at the time of the storm.   Following a rainstorm, the resulting available
 moisture is usually much less than the total precipitation because of
 evaporative losses and slow infiltration rates of soils.   Rain showers
 delivering less than 1/4 inch are likely to result in high runoff losses
 and minimal additions to soil moisture.  The final soil moisture content,
 therefore, is reduced by runoff during and following rain events, and by
 evaporation caused by the  action of wind and sun.

     Irrigation has been shown to be most effective if applied when 60%
 of the field capacity has  been depleted.  The rate of water use by field
 crops  is determined by hours of sunlight,  the drying effects of wind,
 humidity,  wind speed and direction,  the leaf area, root volume, and
 temperature.   Consumptive  use,  therefore,  will vary widely among plant
 species,  and even widely for a given crop  depending upon  its growth
 stage.   For example,  the highest water requirements for any crop are
 usually during the flowering stages  (Israelson and Hansen 1962)'.
                                                                     i
     The amount of readily  available  moisture is also a function of the
 soil type.   As shown in Table 3-1,  the light sandy soils  drain easily
 and, therefore,  contain less readily available moisture than the heavier
 clay soils.   The rate of water extraction  by plant roots  has been deter-
 mined  to  be a function of  the root  density and the gradient in water
 potential  (determined by the concentration of solutes  in  the root cell
 or soil and the  turgor pressure).   Usually the rate of extraction at the
 surface is  greater than subsurface  rates because of the greater surface
 area of roots in the  topsoil layers  (Janick _et ad. 1969).   Experimental
 observations  indicate that when the  depth  of the root  zone is divided
 into four  equal  horizontal subsurface zones,  the following fractions of
 available  water  are extracted (where D = depth of the  roots):

           Zone 1 (surface  to D/4)        40%

           Zone 2 (D/4 to D/2)            30%

           Zone 3 (D/2 to 3D/4)           20%

           Zone 4 (3D/4 to D)             10%

 To  aid  in making decisions regarding irrigation,  indices  of consumptive
 use have been  developed.  Consumptive use, or  evapotranspiration,  is the
water loss from a unit surface of land directly  (evaporation)  and  from
plant surfaces (transpiration)  (Israelson and  Hansen 1962).  These
indices are empirically derived constants, which compare the water needs
of a variety of  crops  to one baseline crop for a given  region.   In
Table 3-2 the  consumptive use indices of 26  crops  are presented  for  the
Western States, using  alfalfa as the baseline  crop  for  comparison.
                                   3-2

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                     TABLE  3-1.   COMMON WATER CAPACITIES OF SOIL BY SOIL TYPES
               Soil DescriDtion                  Readily Available Moisture




               light,  sandy - coarse to fine               Q.7 - 0.9




               medium,  loamy - fine sandy loam             1.5




                               silt loam                   ]__g




               heavy, clay  - clay  loam                      2  1




                             clay
              Source:   Janick _et_ al.  (1969).
                                             3-3

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TABLE 3-2.  SEASONAL CONSUMPTIVE-USE REQUIREMENTS OF COMMON IRRIGATED CROPS
            IN RELATION TO THE REQUIREMENTS FOR ALFALFA—WESTERN STATES
         Croos
Relation of Seasonal Consumptive
Use of Crops listed to the Season-
al Consumptive use of Alfalfa—
(Optimum Yield)	
      Alfalfa
      Almonds3
      Apricots3
      Artichokes
      Avocados3
      Beans
      Berries
      Clover
      Carrots
      Corn
      Citrus3
      Cotton
      Grain
      Grain-Sorghum
      Grapes
      Hops
      Lettuce
      Melons
      Pasture
      Peaches3
      Potatoes—Winter
      Potatoes—Spring or  Seed
      Seed Peas
      Sugar Beets
      Strawberries
      Tomatoes
      Walnuts3
       1.00
       0.42
       0.50
       0.50
       0.52
       0.42
       0.40
       0.90
       0.40
       0.65
       0.70
       0.65
       0.50 (variable)
       0.35 to  0.40
            (variable)
       0.50
       0.15 (Plant  use  only)b
       0.40
       0.90 (variable)
       0.65
       0.50
       0.30
       0.30
       0.82
       0.60
       0.45 to  0.50
       0.60
 3Add 20-25% for permanent grass—legume cover.

 bWater may be applied in addition to that required for growth for  the
  purpose of quality improvement.
Source:  Israelsen and Hansen (1962).
                                  3-4

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      Table  3-3  presents  data on water use by various crops.   The data
  given  are  the  estimated monthly evapotranspiration amounts  (in inche=)
  for  neld  crops  grown in the Sacramento  Valley.   These values  do not
  include water  lost  through  deep percolation or  runoff from  the field
  In trie Sacramento Valley, evaporation from  the  soil accounts  for apDrox-
  mately 10-20%  of the seasonal  total  evapotranspiration (Henderson  D.W
  Professor  of Agronomy,  U.C.  Davis, California,  personal communication  '
  iy/y).  mus,  tne total  amount  of water  actually  utilized by a criven
  crop over  its  growing season may be  estimated from Table 3-3 bv°reducina
  the figure to  80-90% of  the  seasonal  total."

  3.1.1.2  Crop  Physiology

     The rate of water intake by a plant varies with  its  growth  stage  as
 noted above.   As measured by evapotranspiration,  the  intake will  inc-ease
 steadily during the vegetative stage of the plant's  growth, the  flowerin*
 stage occurs near maximum evapotranspiration, and  during the fru^'tin*
 stages,  the evapotranspiration begins to  drop.   Transpiration  (water"loss
 from plant  surfaces) is  virtually at a standstill  in  annuals when the
 iruit has  completely matured, dried,  or fallen from the plant.   Figure
 3-1 presents  the curve  for consumptive use of water over the life cycle
 of an annual  crop.   The  difference between the curves for consumptive
 transpiration indicates  the  amount of water evaporated from the soil
 surface.  Note  that  as  the plant matures  and the leaf area increases,
 the proportion  of water  evaporated from the soil surface diminishes.'
 The amount  of water  a plant  takes in  through its roots is much  greate^
 than  the amount finally  retained by  the plant;  approximately 99% of the
 water brougnt into  the plant is vaporized from leaf surfaces.   Loss
 occurs^mostly through the stomata (80-85%) and  through the  cuticle
 (10-15%).   The  rate  of transpiration  can  be  as much as 1.25  g per 100
 cm^ of  leaf surface  (Israelson  and Hansen 1962;  Wilson and  Loomis 1967).

 3.1.2   Contamination Model

    Much of the research  necessary for a  model that completely  and
 accurately  follows all the biological  and  physical processes,' is either
 lacking or  ongoing.  Hence the  present  contamination model for  wate^-
 contact through irrigation is extremely simplified.   It  estimates  the
 volume 01 water that can  be associated  directly with the plant.   The
 resulting estimated  concentration of the  contaminant  in  the edible por-
 tion represents a (not necessarily the only.) worst  case  scenario,  but  is
 primarily an attempt to determine the  importance of the  water-borne
 route of contamination.

    The assumptions made  in this analysis are listed below, followed by
the resulting conclusions and necessary discussion.  The  symbols used
in the model are shown in Table 3-4.
                                  3-5

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Croo and Growing Period — '
ArtichoKes
Broccoli
Brussels Sprouts
Carrots
 5,15-  4/15
 7/1  -  5/1
 7/15-  5/15

 2/1  -  5/15
 3/15 -  7 '1
 8/15 - 12/1
10/15-  3/1

 4'15-  8/15
 7/15-  3/1

12/1  -  3. "31
 1/15-  5/15
 Cauliflower
Ceierv
 Cucumbers
 Lettuce
Onions
Pepoers
 Potatoes
Spmacn
Tomatoes
 5/15- 8/1
 3/1  -11/15
 12/1 - 5/1

 1/15- 7/1
 8/1  - 1 /1

 3/15- 6/15
 7/1  - 8/31

12/15- 4/15
 3/15- 7/15
 8/15-11/15

 2/15- 9/15
 3/1  - 10/1
 3/15 - 10/15

 2/15 - 9/1
 4/1  -11/1

 4/1  - 8/31
 6,15 - 12/1

 9/15 - 11/15
11/15- 1 /31
 1/15- 4/15

 3/1  - 7/31
 5/1  - 10/15
                                          TABLE 3-3
                                NORMAL CROP WATER USE- '
                               CENTRAL COASTAL PLAINS £•'
                     EVAPCTRANSPIRATION .'CONSUMPTIVE USE) TABLE

                                ESTIMATED MONTHLY EVAPOTRANSPIRATION (inches)-
Jan

1.7
1.7
1.7




1.8


1.8

1.5
.5




1.5

.6





1.6














1.7
.6



Feo

2.2
2.2
2.2

1 .4


2.2


2.2

2.3
1 4




2.2

1 .5





2.1



.7



~f







1.8



Mar

3.1
3.1
3.1

2.5
.9






3.3
3.1




3.1

2.9


.8


3 .1
1.3


2.0
1.7
9

2.0







3.1

.8

Aor

1 .8
3.8
3.8

3.9
f\ O



s



4 .1




3.9

4.1


2.1


1.8
3.1


3.7
3-0
2.3

3.6
1.8

2.4




1.8

1.5

May



2.1

2.2
4.3



2.6



2.3


1 1



4.S


4.1



4.4


4.7
4.6
4.4

4.7
3.1

4.9






4.4
1.2
Jun

7




4.9



4.6






3.2



5 1


2.2



1 4.8


4.9
4.9
4.9

4.9
4.7

6.1
1 .4





| 5.6
1.9
Jul

2.1
1 .7
.8 '






5.3
1.2



1 .1

5.2







2.9


2.5


5.3
5.3
5.3

5.3
5.3

6.4
4.2





5.0
5.0
Auq

3.0
2 4
1 .9



* 1


2.3
2.4



2 5


2 1



2.0


4.4



1 .7

4.7
4.8
4.8

4.6
4.8

3.2
5.7






5.7
Seo

3.5
3.C
2.5



2.1



3 4



3.4


3.4



2.5






3.2

1 .8
3.6
3.9


3.9


4.8

.9




4.3
Oet
j
3.2 !
3.2
2.9



3.0
9 '


3.3



3.5


3.3



3.2






3.2



1.5


3.1


4.1

2.4




1.6
Nov Dec

2.2 1.4
2.2 1.4
2.2 1.4



2.2
1 .4 ' .4


2.2 1.5

1 0

2.3 ' 8


1.2
1 0

|
2.3 1.5
i



6

1.2 j









1.6

1.2
.6 1 .2




TOTAL

24.9
24.6
24.6

10. C
12 4
8.4
7.7

15.7
18.0

8.1
1 1 .4
13.6

9.5
10.0
11 7

19.1
11.5

9.2
7 .3

9.2
16.1
9.3

27.5
27.9
28.0

25.8
26.7

23.0
21.8

4.5
3.5
7.3

17.5
19.7
—'  Estimated evapotranspiration (Consumptive Usei data were obtained from historic measurements, and from calculations basea on data in
   Figure 8 Table 22 and 23. Crop Water Reauirements. No. 24 Food and Agricultural  Organization of the United Nations.
-  Coastal areas of San Mateo.  Santa Cruz. Monterey. San  Luis Obispo and Santa Barbara Counties.
—'  Planting to narvest.
4/
—  Other crops which have similar growing seasons  ground cover, and growth characteristics nave similar ET requirements.
Source: Anonymous (und.)
                                                          3-6

-------
           "ipt/ist ute
CT, g  in inchti pfr day
If                 ioo?
o o»
                            40    50     60     7B
                      P*r:enf of entire Droning period
                      80
   30     36    42
grcwmq pe-iofl m dovs
                       «-Tionrh growing period in days
                                                     49
                            90
                                   )OC
                                                                  60
c

0
0

9 " IB r
;nr,
36
Ef-mo-M
12 ?4 36 43
Four- month
	 '. 	 ! 	 I
'3 ;3 45 60
Five-mcnlh
	 : 	 ; 	 i
i3 36 54
72
45
' 9ro*!"9
60
75
growing
80
54
period ;n
72
period in
90
period in
ioe
63
floyj
64
days
lOS
days
126
72

96
120
144
81

ioe
135
162
90

120
:50
130
  Source: Israelson and Hansen (1962).
     FIGURE 3-1      CONSUMPTIVE USE OF WATER BY
                      AN ANNUAL PLANT DURING
                      VARIOUS PERIODS OF GROWTH
                                  3-7

-------
       TABLE 3-4.  SYMBOLS USED  IN  FOOD  CROP  CONTAMINATION  MODEL
Symbo1             	Description
 ET    =           total volume in liters of a crops consumptive  use  of
                   water or evapotranspiration for a given area in  its
                   lifetime
VT     =           volume in liters of water utilized by the crop for a
                   given area in its lifetime  (0.9 V  )



P      =           concentration (mg/1) of the pollutant in irrigation
                   water or rainwater  (assumed to be the same as in
                   groundwater)


p      =           mass in kg of a pollutant available in a given
                   area P = p V



[p]Fp  =           concentration of the pollutant in the plant and
                   thus in the food part

                   	 P (kg)
                   biomass per unit area (kkg)
                   concentration of the pollutant concentrated in
                   the food part
                   crop  yield  (kkg)
                                  3-8

-------
1.1.2.1  Assumptions

    Assumption:  Farmers will seek  to maximize yield by keeping  the
                 water content of their fields above 60/1 of  field
                 capacity.

         Conclusion:  The applied volume of water will be sufficient
                      to provide for drainage  (gravitational water),
                      runoff, irrigation efficiency, and the volume
                      (in liters) equal to evapotranspiration  (V^).

         Discussion:  While VET will obviously vary, depending upon
                      the cost of water, drought, irrigation practices,
                      accidents, etc., it is an adequate description
                      of the ideal situation.

    Assumption:  Approximately 10% of VET will evaporate.

         Conclusion:  VT = 0.9VET
                      where V =volume of water utilized by plants

         Discussion:  This value was found for the Sacramento Valley
                      area,  and does not apply everywhere.   It will
                      be used here as an example.

    Assumption:  The total mass  of pollutant applied to a given field
                 is a function of its concentration in the total volume
                 of water applied (either irrigation water or rainfall).

         Conclusion:  The total  amount of pollutant in the field that
                      is  available to plants is that contained in the
                      volume (VEX).   So,  if  the pollutant  concentration
                      is  [p],  then the total amount of  pollutant (P)
                      available  to  the plant is P = [p]•
         Discussion:   While P  is  the total amount of pollutant poten-
                      tially available  to  the  plant,  it  does  not  take
                      into  consideration adsorption  of the  pollutant
                      onto  soil surfaces,  release of pollutant from soil
                      into  groundwater, biodegradation in the soil, etc.

   Assumption:   The  transport of  pollutant will  occur at the same
                 rate as water transport.

         Conclusion:   The amount of  pollutant  entering the  plants will
                      equal the amount  available  in  VEj  that  is,  P.

         Discussion:   Although pollutant transport rates are  known to
                      vary,  this method provides  a simple way of
                      estimating pollutant uptake, and gives  a rough
                      estimate.
                                 3-9

-------
Assumption:  Once the pollutant is in the plant, its mass will
             not be diminished through evaporation or by metabo-
             lism.

     Conclusion:  The concentration in the plant will be given
                  by P/biomass for the same area.

     Discussion:  Again, this is meant to be a worst case assump-
                  tion, since both volatilization and degradation
                  may occur.  The relative importance of those
                  removal processes would depend on the chemical
                  and the particular plant considered.

Assumption:  For the purposes of a simple model, it is assumed
             that concentrations in the plant and the edible
             portion are the same.

     Conclusion:  [p]__
     -   LKJ
                               — —     /11  N
                               biomass  (kkg)

                    where  [?]pp = concentration in food part.


          Discussion:  This concentration may be too low in  some  cases.
                       As a maximum, or for lack of information on
                       crop biomass, the pollutant can be associated
                       with the food part:

                            [p]Fp*     P(kg)
                                    crop yield

3.1.2.2  Sample Applications

     Cadmium Contamination of Cucumbers

Region:  California Central Coastal Plains

Growing Season:  3/15-6/15

                 Procedure                        Example

a.  Find the volume of water that is      ET = 9.2 in-
    taken up and transpired by the
    crop plants on 1 acre, e.g.,  find    V   = 9.4x10  I/acre
    V                                     tr
    VET'

         •  Find ET for crop and  region
            from Agricultural  Extension
            Service data.
                                 3-10

-------
 b.   Determine  (choose)  concentration
     of  pollutant.

          •   Search STORE! or other
             ambient  water data files
             for  an average or high
             concentration for the
             region.

 c.   Find  P  —  the  amount  of pollutant
     carried into the plants on one
     acre.
          P =  [p]'VT
0.03 mg/1 is maximum  concentra-
tion of cadmium measured  in
groundwater  (Battelle 1977).
P = 0.03 mg/1 (9.4x10  I/acre)(0.9)


  = 25 g/acre
           =  0.9V
                  £T
d.  Determine yield of  crop  (kg/acre)
    for  the  growing seasons  (USDA
    1978).a

e.  Associate pollutant load with
    crop yield.
Y = 13.24 tons/acre

  = 12011 kg/acre
[p]
   FP;
25 g
        12011 kg

        2 mg/kg
From this example, at a concentration of  0.03  ppm  (30  ppb)  cadmium in
irrigation waters, cucumbers may accumulate  cadmium to a  level  of
2.0 mg/kg.

     Cadmium Contamination of Tomatoes

Region:  California Central Coastal Plain

Growing Season:  3/1-7/31

a.  ET = 17.5 in.

   V£T = l.SxlO6 I/acre

b.  [p] 0.03 mg/1

c.  P - 0.03 mg/1 (l.SxlO6 I/acre)(0.9)

      = 50 g/acre

d.  Yield = 13.75 tons/acre = 12,473 kg/acre
                                 3-11

-------
e.   [?]  *  P      50
       FP -
            Y   12473       6/r^&

     Di-2 Ethyl Hexyl Phthalate  (DEPH)  Contamination  of
     Iceberg Lettuce

Region:  California Central  Coastal Plain

Growing Season:  3/15-7/15

a.  ET = 16.1 inches

   V£T = 1.65xl06 I/acre

b.  [p] =3.8 Mg/1 is the maximum found in ambient water  in  this  part
    of California according  to STORET.  The 50th percentile  concentra-
    tion for the country  (the median) is 0.85 ug/1  (A.D.  Little 1981),
    but the maximum concentration is used as a worst  case.

c.  P * 3.8 yg/1 (1.65xl06 I/acre)(0.9)

      =5.6 g/acre

d.  Y * 11.75 tons/acre = 10,659 kg/acre

e.  [p]Fp*=! = _


3.1.2.3  Limitations of Model and Comparison of Model Results with
         Monitoring Data

     The discussion above shows that there are many gaps  in  the data
necessary to develop a comprehensive model for uptake of  waterborne
pollutants by food crops.  The simple model developed is  meant to
provide a first approximation of contaminant levels in field crops.
Though it is likely that the model will generally overestimate con-
centration,  in some cases it may underestimate,  for example,
for a compound that is actively taken up by a plant and is not lost
through volatilization or degradation.

     In summary, the major assumptions, and sources of uncertainty,
are as follows:

     •  No  losses  or gains of the pollutant to the soil (through
        leaching,  dissolution,  or adsorption)  are allowed.

     •  The uptake of the pollutant is assumed to be
        equivalent to the uptake of water.

     •  No losses  from the plant are considered; i.e.,
        all of the pollutant that enters the plant
        remains there.
                                 3-12

-------
      •  The pollutant is evenly distributed to the plant
         parts (including the edible portion) .

      The results of the sample applications of the model suggest that
 waterborne routes of contamination can be very important for field crops,
 Though the estimated concentrations are not expected to reflect accu-
 rately real situations, it is useful to compare the model results for
 cadmium with actual measurements shown in Table 3-5.  The estimated
 concentrations of cadmium are substantially higher than measured concen-
 trations.

      The possible reasons for this difference are numerous.   First,
 worst-case assumptions were made in many cases, especially with regard
 to the concentration in irrigation water.   In addition,  cadmium is
 bound to the soil to some extent and hence unavailable for uptake.
 Measured concentrations of DEHP in lettuce were unavailable, but con-
 centrations of this compound in other foods are generally less than
 0.5 '^g/kg  (Arthur D. Little 1980).
 3.2  LIVESTOCK AND POULTRY

      Livestock come into contact with water via two routes:   ingestion
 and dermal  absorption.   The following section estimates the  total volume
 of  water  to which four  of the  most  common livestock species  — cattle,
 sheep,  swine and  poultry — are likely to be exposed.   This  provides a
 first approximation of  the mass of  a  priority pollutant potentially-
 available to livestock  over their lifetime as a function of  water uptake.
 In  order  to estimate tissue concentration,  further  information would be
 necessary on distribution,  metabolism,  and excretion of the  pollutant.
 Again,  the  goal is  to determine the potential importance of  waterborne
 routes  of exposure  by estimating the  upper limit  of the amount of a
 pollutant via  water each species can  possibly be  exposed to  in their
 lifetime.

 3.2.1   Ingestion

     Water  intake must  compensate for water  loss  in respiration,  sweat-
 ing, urination and  defecation.   Losses will  be  greater  under certain
 environmental  conditions  (low humidity, high temperature) and require
 increased water consumption.  Table 3-6 presents  estimates of average
water consumption per day  for several livestock species.  The water
 consumption  figures  given  are approximate values, and represent average
 rates over a variety of  climatic and regional conditions.

3.2.2  Dermal Absorption

     With the exception of horses, most livestock found  in the U.S.  have
only a slight ability to sweat  (Brody 1964).  When  subjected  to a high
ambient temperature, cattle and swine in particular are not very effec-
tive at lowering their basal temperature and respond only by  panting,
a less efficient heat-loss process than sweating.   As a result,
                                 3-13

-------
              TABLE 3-5.   COMPARISON OF ESTIMATED AND MEASURED
                          CADMIUM RESIDUES IN FOOD CROPS
  Crop

Cucumbers

Cucumbers

Cucumbers in
sludge/amended
soil

Garden fruits

Tomatoes

Tomatoes

Tomatoes
Method

Calculated

Measured


Measured


Measured

Calculated

Measured

Measured
Result
(mg/kg)

  2

0.005


0.02


0.01 (max)

  4

0.025

0.6
  Source

This  report
          a
Stoewsand (1980)
FDA  (1977)

This report

Stoewsand  (1980)

Stoewsand  (1980)
 Includes green peppers, tomatoes, cucumbers, etc., in a composite
 sample.
                                    3-14

-------
TABLE 3-6.   AVERAGE DAILY WATER CONSUMPTION OF POULTRY AND LIVESTOCK
                                             Daily Consumntion
  Species                                    (Gallons)      (Liters)


  Beef  Cattle  (all  ages;  range  and             10           38
   feedlot,  etc.)
 Dairy  Cows  (in milk)                          13            49.4


 Lambs  (on feed)                               0.4           1.52


 Swine  (all but boars)                         0.9           3.42


 Chicken

   Broilers                                    0.033         0.13

                                               0.064         0.24
 Turkeys                                      0.082        0.31
 Source:  Arthur D.  Little, Inc., estimates.
                                3-15

-------
 temperatures commonly encountered during summer will cause heat stress
 and decreased productivities  in these animals.   Figure 3-2 shows a sharp
 decline in various  productivities in  cattle at  temperatures above 18°C.'
 In  hot  environments,  two  management practices are  commonly used to cool
 animals:   wet blankets and hosing down.   Wet blankets,  made of moisture-
 holding material, are placed  on animals  during  the middle part of the
 day (at peak temperature)  throughout  the summer months.   Hosing is the
 direct  spraying of  animals with water.

      In the hotter  regions of  the U.S.,  the exposure period to water
 used for  cooling purposes  is  estimated to be from  10:30 a.m.  to 4:30 p.m.
 for a total of 6 hours per day (Currie,  B.,  Prof,  of Environmental
 Physiology,  Dept. of  Animal Science,  Cornell Univ.,  Personal  Communica-
 tion 1980).   As  an  upper  limit,  the maximum number of days per year when
 cooling with water  is required is estimated  to  be  90 days (July-September)
 Therefore,  the maximum period  of exposure to water is 540 hours per year
 per capita.

      As a  worst  case,  cattle,  sheep and  swine are  all assumed  to require
 dermal  contact with water  for  cooling purposes.  Poultry  are assumed to
 find relief  from the  heat  through panting or artificial  temperature
 regulation in their housing.

      Calculating  the  amount of water absorbed through the skin during
 the  period  of exposure to  water  requires  data on the body surface  area
 and  a skin  absorption coefficient  for each species.   Table 3-7 presents
 average surface  areas  calculated  for swine,  sheep,  and dairy and beef
 cattle.   These values  are  based  on a large,  full-grown animal  to provide
 an  upper limit.

      Skin absorption  coefficients for water  uptake specific to  each
 species were not available.  As an approximation of  these  coefficients,
 data  for human skin were used  (U.S. EPA 1979),  although the hairless
 skin of man would presumably have a higher potential  for  absorbing
water than the hides of swine, sheep,  and cattle.  Hair cover  acts  as
an initial external barrier, and animals  constantly  exposed to water via
a wet blanket or hosing will have saturated  fur, which will not  prevent
water absorption.  A more important parameter in determining absorption
may be  the fiber weave pattern making up  the skin collagen and this
varies according to  the species  (Yates 1971).


     The water flux through human skin was estimated  to be 0.2-0.5  mg/
cm2/hr  (Scheulpein and Blank 1971).  As a first approximation  of water
absorption in livestock, a rate of 0.3 mg/cm2/hr was multiplied  by  the
surface area of each livestock species and the duration of daily water
exposure (1.5 hrs/day), in order  to estimate daily water  uptake  through
 skin.   Table  3-8 presents  the results.
                                  3-16

-------
             >   »   ftio	2>	Jo'c
             (NVItONMENTAt 	
  Source:  Brody (1964).
FIGURE 3-2
INFLUENCE OF ENVIRONMENTAL

TEMPERATURE ON FEED CON-

SUMPTION, HEAT PRODUCTION,

AND FEED UTILIZATION IN
DAIRY CATTLE
                      3-17

-------
    TABLE  3-7.   REPRESENTATIVE  BODY SURFACE AREAS AND WEIGHTS
                 FOR VARIOUS  LIVESTOCK SPECIES
 Adult
Species

Swine
  Equation to
   Calculate
 Surface Area
                S = 0.10  (W)
            0.63
Weight (kg)    Surface  (m2)
   (W)          Area  (S)
                            250
                                                            3.24
Sheep
S = 0.12 (W)
                            0.57
                                              70
                                           1.35
Cattle (beef)   S = 0.13 (W)°>56
                            700
                                                            5.10
Cattle (dairy)  S = 0.12 (W)
                            0.60
                            500
                                                           5.00
 Source:   Brody (1964).
                                3-18

-------
 TABLE  3-8.   ESTIMATES  OF DAILY WATER ABSORPTION THROUGH SK^

             OF  VARIOUS LIVESTOCK SPECIES        ^^Oh =>K
                                          Estimated

 p£Cles                             Water Absorption fg/dav)


Swine                                         , -
Sheen
                                              o





Cattle (beef)                                23






Cattle (dairy)                               23
                             3-19

-------
 3-2.3  Comparison of Two Exposure Routes

      This analysis indicates that ingestion of water may be a far more
 significant  exposure route for swine,  sheep and cattle than dermal
 absorption (Tables 3-6  and 3-8):  for beef  cattle ingestion is  about 36 kg
 as  compared  to  23 g/day for dermal absorption.   To  the degree  that water"
 tlux  across  human skin  represents a worst  case for  absorption  across the
 skin  of  the  three animal species  examined,  dermal absorption can be ruled
 out as a significant route.

      By  contrast,  the water consumption  by  livestock and  poultry appears
 co be an important potential source of contamination.   Water consumption
 represents a larger mass  than does  food  consumption for livestock.  'For
 example,  for beef cattle,  water consumption is  about 38 kg,  and  food
 consumption  (as corn equivalent)  is about  7 kg.   Thus,  based strictly
 upon  considerations  of  mass  intake, water consumption  represents a  larger
 source.                                                                °

 3.3  AQUATIC ORGANISMS

     For fish and  other edible aquatic species  constantly  immersed  in
water, water is obviously  a primary route of contamination.  Consider-
able research has  been  conducted on pollutant uptake in aquatic  species,
and methods have been reported to estimate  pollutant uptake  (bioaccumula-
 tion)  for certain  groups of chemicals.

     The bioconcentration  factor  (BCF),  the chemical concentration  in an
organism's tissue  divided by the concentration  in water, is  commonly
used to express pollutant uptake by aquatic species.  This is an  equili-
brium expression assuming  that any  further  uptake of pollutant is
balanced by the depuration, or excretion, rate  of the substance.  For
36 organic compounds, Kenaga and Goring  (1978)  derived regression equa-
tions  relating each chemical's bioconcentration factor to  its water
solubility and octanol-water partition coefficient.   Table 3-9 presents
the two equations.

     Using these equations to estimate contamination of edible fish
species requires that a number of assumptions be made  (Kenaga and Goring
1978):

     (1)   Although considerable species variability in
          pollutant uptake is common,  these equations
          average data from several fish species and it
          is assumed that they are applicable to all fish
          species as a first approximation.

     (2)   Although these estimation equations assume concen-
          trations in the fatty portion of the  fish, the
          pollutant is assumed to be evenly distributed
          throughout the body of the fish.   This provides an
                                  3-20

-------
       TABLE 3-9.   REGRESSION EQUATIONS CORRELATING BIOCONCENTRATION FACTORS
                   (BCF)  IN AQUATIC SPECIES TO OTHER PARAMETERS
                                 Regression                          Correlation
                                  Equation                         Coefficient  (r)

Parameter BCF Correlated
  with Water Solubility     Lo§ BCF = 2*791 ~ °'564           ~ 0-72


Octanol-Water Partition
    Coefficient             Lo§ BCF = 1'495 + °-935 (L°§ K  )           0.87
                                                          ow
     Note:
       WS  =  Water  Solubility
       K   = Octanol-Water-partition  coefficient
    Source:  Kenaga and Goring  (1978)
                                      3-21

-------
          upper-limit estimate of tissue residue levels because                 ^
          fat is usually discarded during evisceration and  the
          remaining muscle portion is eaten.                                    I

      (3)  Variability in fish parameters likely to affect
          pollutant uptake, such as fat content, was assumed                    |
          to be expressed adequately in the equations.                          '

      (4)  All fish caught for consumption are assumed to have                   1
          been chronically exposed to the pollutant and to                      f
          have reached equilibrium tissue concentrations.

     For inorganics, no method exists at this time to estimate the              I
BCF in fish or other aquatic organisms.  Metals and other inorganics
are commonly detected in fish tissue at high concentrations, but
assimilation does not appear to follow a predictable pattern based on           I
the current state of understanding.  In addition, species variability           |
in uptake patterns is high.  For these reasons, no estimation of                I
inorganic pollutant concentrations in fish was possible.

     The waterborne route is very important in determining  residues
in aquatic organisms.  Residues of organics can be estimated from the
water concentration and a measured or estimated bioconcentration factor.
It should be pointed out, however, that consumption of contaminated food
items may also contribute to the body burden of aquatic species in some
situations.
                                 3-22

-------
       4.0  WATER-RELATED  CONTAMINATION OF FOOD DURING PROCESSING
 4.1  INTRODUCTION

      Of the 15 trillion gal of water consumed by the manufacturing
 industries of the United States in 1973, only 5% was accounted for by
 establishments processing food and kindred products (Table 4-1), whereas
 four other major industry groups accounted for a total of 85%.  An
 even smaller quantity, possibly about 1 1/2%, actually came into direct
 or indirect contact with food products.  However, when the nature of the
 U.S. food processing industry is taken into consideration, it can be
 seen that this use was spread over an exceptionally broad area of opera-
 tions,  involving a complex set of interrelationships.

      The food processing industry in the United States is comprised of
 nearly 30,000 establishments that run the entire spectrum from the manu-
 facture of bulk commodities in huge quantities,  such as fats and oils,
 starches,  and sweeteners,  which are basic ingredients  for the rest of'
 the industry,  to the production of highly processed convenience foods
 for both retail and institutional markets.

      While there are at least 50 food processing firms in the U.S. with
 over $1 billion annual sales,  nearly 50% of total food industry sales are
 derived from about 22,000  establishments with fewer than 100 employees
 each.   In  1978  the food processing industry employed over 2  million
 people,  and produced shipments worth $230 billion.

      In addition  to this extreme fragmentation,  the food industry is
 also widely diversified in  terms of  types of  products  manufactured and
 processes  employed.   The U.S.  Department  of Commerce has  classified
 this  industry into  47  individual subsectors at the  four-digit  SIC code
 level.   Each of  these  subsectors  is  really  a  complete  industry in itself,
 with  its own unique  characteristics  and  distinctions.   The "food  industry"
 is, therefore,  structurally complex,  differentiated  and  interrelated.

 4-2  UTILIZATION  OF WATER IN FOOD PROCESSING

 4.2.1  Introduction

     Water comes  into intimate contact with foods during preparation
 and preservation  operations.   It is universally used for washing  fresh
 raw foods at various stages of preparation; it serves commonly as a
 carrier of raw materials between unit processes;  and it is the medium
 through which many unit processes such as soaking, blanching, qualitv
 separation, and preheating are applied.  Water also serves as an in-'
gredient of formulation or as a principal portion of the brine or syrup
added as a packing medium.   Through its direct contact  with raw foods
in preparation and processing, or its indirect contact  with foods when
                                  4-1

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        TABLE  4-1.   WATER INTAKE OF MAJOR U.S.  INDUSTRIES,  1973
    Industry

Primary metal industries

Chemicals and allied products

Paper and allied products

Petroleum and coal products

Food and kindred products

Transportation equipment

Total U.S. industries
 Water Intake
(billion gal)
% of Total
4,941
4,176
2,415
1,283
804
242
15,024
33
28
16
9
5
2
100
U.S. Department of Commerce (1973).

-------
 used to wash food processing equipment, water exerts influence upon the
 efficiency of the processing operations and upon the quality of the
 finished processed food.

      The quantity of water used in food processing is subject to wide
 variation, depending on the physical characteristics of the raw food-
 stuffs, seasonality and changes in the product mix.  Table 4-2 shows
 the process water usage by U.S. food industry groups in 1973.  For the
 purposes of this discussion, process water includes water that comes
 into direct contact with the food in addition to water that is con-
 sumed in production.   It can be seen that the largest users of process
 water are the meat and poultry packers, processors of canned and frozen
 fruits and vegetables, and brewers of malt beverages.  Each of these
 industry groups consumed over 20 billion gal of process water in 1973.
 A more detailed review of amounts of process water used, and type of
 use for each major food item, follows below.

 4.2.2  Meat Products

      The meat products group is the second largest user of process water
 in the U.S.  food industry,  accounting for 28% of total usage.

      The meat packing industry  buys live animals and delivers primal
 cuts,  quarters  and sides to meat cutting facilities,  which reduce  them
 to retail film-wrapped packages.  Use of process water in  this  sector
 is mostly confined to washing the carcasses  after de-hairing,  and
 washing viscera  and major  cuts.   Much of the  water is used for  cleaning
 the facilities and the processing equipment.   In addition,  water  troughs
 are provided  for the  animals prior to slaughter.   Typically,  a  packing
 plant  uses  about 550  gal of water for every  100  hogs  slaughtered.

     Water  is also used  quite extensively  in  poultry  dressing plants.
 To assist in  defeathering  the slaughtered  birds,  they are  first immersed
 in hot  water  to  loosen  the  feathers.   Following  the defeathering operation,
 which is  carried out  by  a variety  of  machines, the birds are  subjected
 to a strong spray of  water  to rinse off  detached but  adhering feathers.

     During the  evisceration operation,  both the interior  and exterior
 of the  birds are frequently  sprayed with water to remove debris.  Follow-
 ing evisceration, the birds are  cooled by  conveying them through a
 chilled bath.  The chilling is accomplished by either a refrigerated
 jacket on the tank, or by adding water ice to the water bath.  In some
 operations, water is absorbed by the bird up to the legal limit of 8%
 of  the original weight.

     The use of water  in the manufacture of sausages and other prepared
meats is mostly  confined to washing operations following meat cutting
and trimming; to curing for varying lengths of time in brine baths; and
to process line cleanup.  Water is also used in production formulation
for the purpose of facilitating grinding, chopping and mixing, and to
prevent overheating of the mix.   In this case, not more than 3% of water
                                  4-3

-------
              TABLE 4-2.   PROCESS  WATER USAGE  BY  U.S.  FOOD
                          INDUSTRY GROUPS.  1973
                                                         Process Water Use
bic Code                     Industry Group               (billion gal)

  20        Food and  kindred products                         232.1

 201        Meat Products                                       54.5
              Meatpacking  plants                                36,2
              Poultry dressing  plants                          22.8
              Sausages and other  prepared  meats                  3.2
              Poultry and  egg processing                         2.3

 202        Dairy Products                                     11.4
              Fluid milk                                         6^0
              Condensed and evaporated milk                     3.0
              Cheese,  natural and processed                     1.3
              Ice cream, frozen desserts,  butter                 l.l

 203        Preserved  Fruit  and Specialties                    74.0
            .  Frozen  fruits  and vegetables                      27.0
              Canned  fruits  and vegetables                      20.5
              Canned  specialties                                16.0
              Dehydrated fruits, vegetables, soups               5.3
              Frozen  specialties                                 3.4
              Pickles, sauces, salad  dressings                   1.8

 204        Grain Mill Products                                 13.4
              Corn wet milling                                   9.2
              Dog, cat, and other pet foods      *               1.4
              Cereal breakfast foods                            1.0
              Flour, other grain mill products                  0.9
              Prepared foods                                    0.5
              Rice milling                                      0.3
              Blended and prepared flour                        0.1

205        Bakery Products                                     1.7
             Bread, cake,  and related products                 1.5
             Cookies and  crackers                              0.2

206        Sugar, Confectionery Products                      19.2
             Raw cane sugar                                    8.6
             Beet sugar                                        5 __ 7
             Cane sugar refining                               3.5
             Confectionery products                            1.8
                                  4-4

-------
             TABLE 4-2.  PROCESS WATER USAGE BY U.S. FOOD
                         INDUSTRY GROUPS, 1973  (Continued)
                                                         Process Water Use
SIC Code                       Industry Group             (billion gal)

 207        Fats and Oils                                      2.8
              Shortening and cooking oils                      1.1
              Animal and marine fats and oils                  0.9
              Soybean oil mills                                0.6
              Other vegetable oil mills                        0.2

 208        Beverages                                         34^3
              Malt  beverages                                  21.0
              Bottled and canned  soft  drinks                    6 4
              Malt                                              4]5
              Distilled  liquor, except brandy                  1.2
              Flavoring  extracts,  syrups                        0.8
              Wines,  brandy,  and  brandy spirits                 0.4

 209        Miscellaneous Foods                                10.8
              Canned  and  cured  seafoods,  other food
                preparations  n.e.c.                             6.0
              Fresh or frozen packaged  fish                     1.9
              Roasted coffee                                    ]_]g
              Manufactured ice                                  1_0
              Macaroni and spaghetti                            0.1
Source:  U.S. Department of Commerce  (1973), and
         Arthur D. Little, Inc., estimates.
                                  4-5

-------
 and/or ice may be added to uncooked sausage, while cooked sausage may
 contain not more than 10% added water.                                          I

 4.2.3  Dairy Products                                                           "

      Despite the high-volume production of the milk industry, dairy             I
 products account for a relatively low share of 5% in process water'              '
 usage.  With a few exceptions, water only comes into direct contact
 with the products during sanitation of processing equipment.                    1

      In the case of fluid milk, process pipes and pumps are primed with
 water to facilitate startup.   The first run of the water and milk mixture       1
 is discarded.   Process water  in the form of steam comes into direct              I
 contact with milk when the latter is heated by direct steam injection
 Applications of this process  include the deodorizing of milk (mostly            '
 used  in the South to avoid garlic-like flavors caused by feed)  and the
 heating of skim milk prior to drying.   Culinary steam is also used in
 the manufacture of processed  cheese when the shredded cheese is cooked
 with  live steam for a weight  gain of up to 6%.   In these instances,
 however,  the risk of contaminant  carryover into the steam is greatly
 diminished.

      Water may  also be added  directly  during the processing  of  cheese
 in order  to control texture characteristics;  and in the form of brine
 during one continuous butter-making process.

 4.2.4  Preserved  Fruits  and Vegetables

      This  category  of food products  accounts  for the  highest usage of
 process water in  the  U.S.  food  industry, or  about  one-third  of  total
 water used.  The  largest use  is in  the  canning  of  fruits  and vegetables
 followed closely  by  freezing.   This  is  no  cause  for surprise as  much
 of  the processing equipment,  insofar as raw material  preparation is
 concerned,  is common  to both  industries.

      Water  is used to  clean raw fruits  and vegetables,  and also  to
 transport  them between various process  steps.   It  is also used  to
 effect quality separation and facilitate further processing,  and  is
 added directly to canned goods in the form of brine, syrup or sauce,
 and to some frozen foods to prevent quality loss due to dehydration!

     Water consumption can vary over wide limits,  depending upon the
 physical characteristics of the raw material.  In  the canning industry,
water use can range from a low of 300 gal/100 cases of finished product
 in No. 2 cans for sauerkraut to 25,000 gal/100 cases for lima beans
 (see Table 4-3).  At a usage level of 7,000 gal/100 cases, tomatoes
are fairly representative of the group as a whole.
                                   4-6

-------
       TABLE 4-3.  WATER  REQUIREMENTS  OF  SELECTED  CANNED  PRODUCTS
  Product                                          TT    Total
  ~~    ~                                          Water Consumption
                                                     (gal/100 cases
                                                       No. 2 cans)*
                                                         8,000

                                                         7,000
  Beets
                                                         2,500
  Corn
                                                         2,500
  Grapefruit juice
                                                           500
  Grapefruit sections                                     ..  fnn
                                                         5,600
  Green beans
                                                         3,500
  Lima beans
                                                       25,000
  Peaches
                                                         6,500
  Pears
                                                         6,500
 Peas
                                                         2,500
 Pork and beans
                                                        3,500
 Pumpkin
                                                        2,500
 Sauerkraut
                                                          300
 Spinach
                                                       16,000
 Squash
                                                        2,500
 Succotash
                                                       12,500
 Tomato  products
                                                       7,000
 Tomatoes, whole
                                                         750

*24 cans/case


Source:   Jordan (1963).
                                4-7

-------
      Water enters the tomato processing operation together with the            I
 tomatoes at the rate of about 2500 gal of water per ton of tomatoes.
 About 10% of this water is initially used to soak the whole fruit so            I
 that contaminants are loosened on the surface.   Following the soaking          |
 operation, about one-third of the water is used in a high-pressure spray
 to remove the surface contaminants.   About 5% of the water is used to          •
 generate steam,  part of which is used in direct contact to scale the            I
 tomatoes prior to peeling or pulping.   The balance of the water is
 used to clean up the facilities and  the processing equipment.   The
 residual water contained in solid packed tomatoes or tomato juice is            J
 extremely small.   Water is added as  an ingredient in tomato sauces.             *

      The quantities  of water used in raw material preparation for              j
 dehydration compare  closely with those for canning or freezing,  on a            1
 per unit basis.   In  the case of pickle manufacture,  the product  is
 soaked in brine  for  a period of up to several weeks  to ensure thorough
 penetration of the pickling solution.

 4.2.5  Grain Milling Products

      Despite the high volume and diverse nature of the products  in-
 cluded in this industry group,  process water  usage accounts for  67,
 of  the total food industry use.

      Seventy percent  of the  group  total is  accounted  for  by the  corn
 wet milling industry,  which  processes  whole yellow corn into a wide
 variety  of products  such as  corn starch,  chemically modified starches,
 corn syrup,  dextrose  and high  fructose corn syrup  (HFCS);  and by-products
 such as  corn oil  and  animal  feed.

      Water is  used extensively throughout  the process.  Cleaned  corn  is
 first  steeped  and softened in  warm water tanks  for several  days.   The
 "steepwater"  or water  drained  off  from this process,  containing  about
 900 Ibs  solid  matter  per 1000  gal, is  a good  protein  source,  and is
 converted  to  animal  feed or  used as  a  fermentation nutrient  after  con-
 centration.   The  kernels are subsequently milled  to remove  the corn
 germs, which  are  washed  and  separated  by flotation.

     After  subsequent  grinding  operations, starch  is  removed from  the
 gluten by  flushing with  water.   The  starch is finally  cleaned by a
 series of washings and  filtering processes; the wash water  is re-used
 in  earlier  stages of the process.

     Rice milling is somewhat  similar,  insofar as  a hot water steeping
 process may be used to  condition the product prior to milling.

     Dog,  cat, and other pet foods include moist and  semi-moist product
 categories.  In both of  these  instances, water is used  in product
 formulation to a greater or lesser extent, as well as  coming into in-
direct contact with the product during processing line cleanup operations.

-------
       Cereal  breakfast  foods  can also  be  classified  into  two  general
  types:   those made  from whole  grains  or  their  mill  products,  and  those
  made  from fabricated cereal  products.  Considerable variations  exist
  within  each  type  in regard to  the  cereals  and  other raw  materials used,
  and the type of processing employed.   The  grains may be  cooked  in steam,
  while water  may form part of the formulation in dough preparation or
  flavoring system.

      A  small quantity  of water  is  used in  the  flour milling  industry
  to wash the  wheat,  which is  then passed  through a centrifuge  to remove
  excess  moisture.  A further addition  of  water  may be made to  condition
  the wheat  prior to  subsequent milling operations.   This  toughens  the
  bran and  assists separation.

  4.2.6   Bakery Products

      Bakery  products take only 1% of the total process water consumed
  by the  U.S.  food industry.   Process water usage is largely accounted
  for by  dough manufacture—typically about 40 Ibs of water are required
  for every 66 Ibs of flour in order to prepare a bread dough.   Similarly,
  cakes  and other bakery products incorporate water to a greater or lesser
 extent  in their formulation.

     Water is also used in  pan  washing, and in  cleaning other equipment
 and utensils.

     Cookie and  cracker production  is  fairly similar to bread production,
 except  that in  general  stiffer  doughs  are prepared,  and so  the quantity
 or process water used is less.

 4.2.7   Sugar, Confectionery Products

     This industry group accounts for  8%  of total food industry  use of
 process  water.  Most of this  occurs in raw  cane sugar and beet sugar
 processing operations.

     Large quantities of water  are  used in  raw  cane  milling.   A  typical
 cane sugar mill processes about  2,000  tons  of sugar  cane  per day
 Around 22% of this quantity is  required in  inhibition water.   This is
 water that  is added  to  the cane while  it  is being passed  through the
 crushing rollers.  The  water mixes with the raw juice, which is sub-
 sequently  concentrated  by evaporators.

     A cane sugar refinery produces white crystalline  sugar from the
 raw sugar resulting  from the milling operation.   Sugar cake is washed
 in hot  water,  and the crystals are then dissolved in about one-half
 their weight of hot water,  prior to recrystallization.  The process
requires a water consumption of  about 0.5 gal for every pound of sugar
•L CX Juried •
                                  4-9

-------
      In the processing of sugar beets, the raw material is conveyed
 to the initial stages of production by water channels or flumes.' Water
 sprays are used in rotary beet washers, where gross contamination is
 removed.  The beets are then sliced and passed into a diffusor, where
 the sugar is extracted with hot water.  Flow rates are high, as a lar
-------
  and  in  the  preparation of  cooled  carbonated water,  the  other major
  formulation component.  Water also  comes  into  direct  contact with the
  product through its use in can and  bottle washing,  as well  as  in the
  sanitizing  of equipment and utensils.

      The production of distilled  liquors generally  involves mashing
  the  grain or other fermentable raw  materials with hot water as the first
  step in the process.  After distillation, the  beverage  is adjusted to
  the desired proof or alcoholic strength by the addition of plain or
  distilled water.

      In the case of wines and related products, the use of water is
  limited to  indirect contact applications such  as bottle washing and
  sanitizing  equipment, with the exception of certain wines based on fruit
  other than  grapes, such as blackberries and peaches, where water is
  used in product formulation.

  4.2.10  Miscellaneous Foods

      This final category accounts for 4% of total process water consump-
 tion and is dominated by the processing of fresh, frozen, canned,  and
 cured seafoods.

      Liberal use of water  is  made at all stages of fish processing,
 including  gutting,  filleting,  cooking,  and canning in brine  or sauce.
 Water comes  into contact with whole  fish and  fillets in the  form of
.ice,  which is  added to  slow down  the rate of  deterioration of  the  product
 before  the preservation process.   Extensive use is made of water  in
 process  line cleanup.

      In  addition to making  ice for commercial  fish harvesting  and  pro-
 cessing  operations,  ice makers manufacture  and  sell  ice  for  institutional,
 wholesale  and  retail  customers.

      The coffee  industry uses water  in  the manufacture of  soluble
 coffee.  Ground, roasted coffee is extracted with  hot  water, and then
 the resulting  liquid is evaporated or spray dried  to a powder.

      Macaroni and spaghetti is produced  from a  dough containing semolina
durum flour, water, and other ingredients.  This category  represents
one of the lowest demands for process water in  the U.S.  food industry.

4-3   SUMMARY OF WATER USE DURING PROCESSING

     Table 4-4 contains a summary  of water use  during processing by
food industry group.  It identifies the process in which water has
direct contact with the food.   The text has discussed quantities of
water associated with most of these particular  steps and the conditions
of contact using representative examples.  For  instance, the following
breakdown was derived for tomatoes:
                                  4-11

-------
FABLE 4-4.   DIRECT FOOD/WATER CONTACT DURING PROCESSING
            BY FOOD INDUSTRY GROUP
N. PROCESS
FOOD ^v
INDUSTRY \^
GROUP N^
Meat Products
Meatpacking
Poul trv
Sausages/Prepared Meats
(Dairy Products
J rluid Milk
C'.ieese
Fruits, Vegetables
Canned/rrozen
Pickles
Grain Milling
Corn wet Milling
1 Pet Foods
Breakfast Cereals
Flour Milling
IBakerv Products
i Bread
Cookies
(Sugar, Confectionery
Cane Sugar
Beet Sugar
Fats, Oils
Animal/Vegetable Oils
Beverages
Malt Bevt?rar:es
Soft Drinks
Distilled Liquor |
V, I n c' s
h 	 	 	 — 	 »~- 	 — 	 _.
Miscellaneous
Canned Seafood
rrozen Seafood
Roasted Coffee
Macaroni /Spaghetti
i
i
K
C
f-
y
•H
U
a

•
1



I


























=
-— f
c
— t
en
en
OJ
y


1


•






















1




1 •£
s








,














1



1





1
i
c
ra
•j
!
«
.
«

i •
f

,
• i



1 ,


.
»




•

•
•
•
•

•
•

•

-------
           process                water  contact  (gal/ton product)

           soak                               250

           spray                              800

           steam                              125

     These values cannot be summed to obtain a total water contact
since these processes involve different  types of contact.  A model
could be developed as for food during growth, however, several factors
need to be taken into consideration before amounts of contaminants
entering food can be estimated.

     •  Detailed assessment of the surface area contacted, and
        the time of contact.  This would vary by crop and
        process step.

     •  Consideration of the rates of absorption or adsorption
        of water or the pollutant under the conditions specified
        for each processing step.

     Thus,  although the opportunities for water contact can be specified,
this information cannot yet be used for calculating the resultant con-
centrations of a water-borne pollutant in processed food.
                                 4-13

-------
                               o
substantial amounts     ater Ire
of water consumption
                                                             in the
                                                 processas th" "l-ir.

                                                        « -
                                                        as wel1 as  estimates
  likelihood  does  not  entail si^nTf-  riC6'  ^ PaSta) *   StSamin§
  Partly  because ofthe stall oSntiti^ T^' °f f°°d C°

  because ,any  Inorg^ic'Sit^St.'^ n°  t^po^^'rei        h-
  presents minimal  potential for  contamination T     re^d^y-   Washing
  brief contact of  the  food  with  wate^    '          * "      relati^ly



 actuaf L^^J^^f a^f JJf ^f-e data as a basis for estimatin,

 Processing.   The  data requirements ?or a ^dT'10^ Previ°us1^ ^ food
 preparation  as home preparation   thS   a moH^ ""i the Same f°r co^rcia
 similar  considerations.   For products   «  h    ^^ d ^ devel°Ped using

 added directly (see water mLx'ngt ll*£ ?  5-1)  Je^°'  C° Wh±Ch Water is
 concentrations in  water  to  estimate  ron,  ,     v°lumes can be used with
 foods.   As an  example, huLnTar* LnT n tratl°ns  in  those particular
 2 I/day  of tap water Is  drinking Xfter  an^ • C°nSidered to  Consume  about
 tea). ' if a person wer£     ™JJat«  a^d ln water-based  drinks  (coffee,

 eggs, soup,  hot cereal   rice  iello * S  J     &S  drled  milk' Peered

about 1.8 1 of water with th^s  produc s    Th" ^^  ^ mi^ht
from drinking water could be complrabl^ %      ,'  lntake °f a PoHutant
tion of  these products.      con>Parable to   mtake resulting from conSump-
                                   5-1

-------
TANLE 5-1.  ESTIMATED WATER USE  IN  HOME  PREPARATION OT E()()l)
                      Water  Ust^ (oz) per Unit of Preparation
Food Group
Fresh Vegetables
Lettuces
Root vegetables
Spinach, cabbages,
b roc eo I i
Li j'uin-s
Torutoes, peppers
Sqnaslies
Corn
Frozen Vegetables
Canned Vegetables
Freeze-dricd Vegetables
Fresh Fruits

Herrles

Fresh Fruits

Dairy Products
Dried Milk
Condensed Milk
Powdered Egj;s
Boiling


32 oz./lb.

32 oz./lb.
32 oz./lb.
16 oz./lb.
32 oz./lb.
48 oz./lb.
8 oz./12 oz. pkg.
8 oz./can










Steaming




8 oz./lb.
8 oz./lb.












Water Mixing







16 oz./4 oz. pkg.



16 oz./4 oz. pkg.



32 oz./5 oz. pkg.
16 oz./can
16 oz./pkg.
Stewing
1
1


16 oz./lb.
16 oz./lb.
16 oz//lb.






48 oz./lb.

16 oz./lb.



Washing
— — 	

64 oz . /head
32 oz./lb.
64 oz./lb.
64 oz./lb.
32 oz./Jb.




32 oz./lb.

32 oz./lb.

32 oz./lb.




-------
                                      TABLE 5-1.  ESTIMATED WATER USE  .N HOME PREPARATION OK  KOOI,  (Continued)
 I
to
                  Food Group
         Meats
  Fronh  (nil  meats)
  Poultry,  fresh  fish
  Freoze-drlcd  (.ill  moats)

 Prepared Foods

   Dry Soup Mix
   Condensed Soup
   Single Serving  Soups
   Boullion Cubes

Hot  Breakfast Cereals

Rice

Pasta

Baking Mixes

Gelatin,  Instant  Pudding

Drinks

  Frozen Juices
  Tea Bags
  Loose Tea
  Instant Tea
  Ground Coffee
  Instant Coffee
  Powdered Mixes
      ,  Source-:  Arthur  I).  LiLtle,  inc. estimate.
                                                                  per Un U oj Preparat i on
                                                                      Water Mixing
                                                                             16  oz./4  oz.  pkg.
                                                                            24 oz./pkg.
                                                                            11 oz./can
                                                                            8 oz./pkg.
                                                                            6 oz./serving
                                                                            12 oz./pkg.

                                                                            16 oz./pkg.
                                                                           48 oz./12 oz. can
                                                                           12 oz./bag
                                                                           J6 02. /tsp.
                                                                              oz./tsp.
                                                                           12 oz./tsp.
                                                                            6 oz./tsp.
                                                                           48 oz./pkg.
                                                                                                  04 oz./lb.
                                                                                                                  Wash ing
                                                                                                               16 oz./lb.

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    6-0  DRINKING WATER CONTAMINATION DURING TREATMENT AND DISTRIBUTION
 6.1  INTRODUCTION

      Much emphasis has been placed on the contamination of drinking
 water supplies, and only recently has contamination in drinking water
 treatment and distribution been considered as a source of human exposure
 to hazardous chemicals.  This Chapter examines such types of exposure.
 Unlike food contamination, drinking water contamination during treat-
 ment and distribution is generally limited to certain types of chemicals.
 Chemicals introduced in water treatment and distribution come in direct
 contact with the water supply and predicting the resultant contamination
 requires specific information on water chemistry and other environmental
 conditions.   This Chapter considers qualitatively the types of such
 contamination that may occur and the conditions that promote the occur-
 rences.

      Figure  6-1 shows the flow of drinking water from the water supply
 to the consumer.   Several sources of contamination have been identified,
 including chemical additions at the treatment plant, chemical production
 at the treatment  plant, pipe corrosion,  and leakage into pipes.   These
 types of contamination will  be discussed individually below.

 6.2  CHEMICAL ADDITIONS AT THE TREATMENT PLANT

      Thousands of chemicals  are used  in  water treatment in the U.S.
 today.   The  U.S.  EPA has compiled a long list of approved  additives,
 however,  has no regulatory authority  except  through the individual
 states.   Thus,  although the  composition  of  some  additives  is  very well
 known,  i.e.,  chlorine,  the composition of  others  is  largely unknown."
 In addition,  even the known  chemical  additives may contain trace con-
 taminants  that  have  not  yet  been  identified.

      With  the  exception  of chlorine and  florine, most  chemicals added
 at  the treatment  plant  are not  intended  to remain  in the finished
 drinking water.   Nevertheless,  little is known about  the fate  of these
 chemicals, and  especially  the fate of any contaminants.

 6.3   CHEMICAL FORMATIONS AT  THE TREATMENT PLANT

     The chlorination of drinking water results in the  formation of
chlorinated organics, particularly trihalomethanes.  The production of
these compounds, especially chloroform, appears to depend primarily on
the available precursors.  Arguello et al. (1979) reported that such
compounds in raw water as resourcinol, A-methoxyphenol, humic acid,
2,6-dimethylphenol, pentachlorophenol, hydroquinone and n.n-diethylaniline
in raw water resulted in a high production of chloroform.  The production
of bromofonn was directly related to the bromide concentrations in raw
                                   6-1

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                                                         Consumer
                             leaching
         Water  supply
         ground or
            surface
to
                             pipe
                             corrosion
                                               chemical
1
Treatment!

chemical
formations
i
i
Pi;
CO]
r
ie
rros ion
                                                                                               Consumer
                                                                                                  1.
chemi cal
addi tions
                FIGURE 6-1.  SOURCES OF CONTAMINATION OF DRINKING WATER IN TREATMENT AND DISTRIBUTION

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 water.  Temperature appears to  influence  the production  of  trihalomethanes,
 usually resulting in a lower production at lower  temperatures.   In addi-
 tion, trihalomethanes continue  to be formed in the distribution  system  if
 the water contains a chlorine residual, an appropriate precursor,'or
 both  (Brett and Claverley 1979).

      The estimation of trihalomethane concentrations, based on these
 variables is complex.  While production ratios (from precursors) have
 been calculated in the laboratory, these ratios are not useful in the
 field for predictive purposes.   The primary reason for this is that in
 the field a composite of precursors will be available, and production
 ratios are not likely to be the same as in the isolated laboratory-
 situation.

 6.4  PIPE CORROSION

      Pipe corrosion is  a well-known problem in water distribution,
 and the  release of metals from  lead pipes  into the drinking water'has
 been studied extensively.  However,  other  chemicals may be released in
 the distribution,  such  as vinyl chloride and asbestos if PVC or asbestos-
 cement piping  is used.   This section will  discuss these types of dis-
 tribution systems  and the resulting  contaminants.

 6.4.1  Metal Pipes

     The release of metals from  distribution systems  depends on the water
 quality and  the  piping material  used.  Important water  quality  parameters
 influencing corrosion are pH, alkalinity,  hardness, temperature,  dis-
 solved oxygen and dissolved  carbon dioxide  (McFarren  et al.  1977).
 In  general, soft waters containing dissolved oxygen and "carbon  dioxide
 promote corrosion, especially at higher temperatures  (Karalekas et al.
 1976).                                                          — —


     Distribution  systems have most  commonly been  examined from a
 materials point  of view,  that is,  the corrosion is measured  as  loss in
 diameter in mils per year.   Though this  is a quantitative measure of
 loss,  it bears little relationship to concentrations  of metals  that
 ™aLiroSSVn thv WStfr*  Jable  6-X  Shows  ^'P*3 of Plumbing  used and  the
 metals that may be released.  These types  of materials  corrode  at
 different rates under different  conditions  and the rate of corrosion
 is  not predictable.

     Even for the same water system, concentrations vary depending
 on  the time of day.  For  example, the maximum sample taken in a survev
 of homes in the Boston area showed 1.5 mg/1 lead in a standing  sample'
 (the water was standing in the pipes for several hours).   In a  running
 sample (the water is run  for several minutes before sampling) the level
of lead was 0.13 mg/1, a difference of a factor of ten (Karalekas
€ L 3.J..  j.9/0y.
                                   6-3

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                        TABLE 6-1.   METALS IN DRINKING WATER RESULTING FROM VARIOUS TYPES OF PLUMBING
o>
Type of Plumbing

Lead

Zinc-lined galvanized Iron



Alloys (solder, brass, bronze)

Iron and steel

Copper and brass

Stainless steel
                                                    Resultant Metal  in
                                                    Drinking Water

                                                    Lead

                                                    Lead, zinc, cadmium
Copper, lead, silver, zinc

Iron, manganese

Copper

Chromium, nickel
                                     Concent rations Found'

                                      Pb - 170-1500 ug/1

                                      Pb - 3.2-24.1 ug/1, Cd
                                      <0.04-0.2 ug/i, 2n-280-
                                      1400 ug/1.
       aPipe exposed to corrosive water and standing water.
       Sources:   Karalekas et al.  (1976)  and McFarren £t  al.  (1977),

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      While most metals are leached from the piping material, as is
 shown in the example given above, small amounts of lead or other metal
 may come from other sources such as lead joints, gaskets and lead-tin
 solder used in the system.  Though these sources probably represent
 insignificant sources as compared with lead pipes, they may significantly
 contribute to lead levels where other types of piping are used.

 6.4.2  Asbestos-Cement Pipes

      Asbestos-cement pipe is commonly used in the United States in
 water distribution systems.  Hallenbeck _et al. (1978) reported that
 one-third of all water distribution pipe sold at that time in the U.S.
 was asbestos-cement.

      Recently,  the release of asbestos into drinking water in the dis-
 tribution has been observed (Sargent 1974; Peterson 1978,  McFarren
 et_ al_.  1977).   The American Water Works Association Standard C400-77
 sets criteria for quality of water that can be transported through
 asbestos-cement pipe using the equation pH + log AH,  where A equals
 the alkalinity (mg/1 as CaCO^).   This equation is used to  determine
 the agressiveness of the water.   Values greater than 12 are non-aggressive,
 10.0-11.9 are moderately aggressive, and less than 10 are  considered
 highly aggressive.  The use of this equation implies that  the release
 of asbestos is  related directly to these parameters.

      While  pH,  hardness and alkalinity may influence the release of
 asbestos  from pipes,  other factors are also important.   For example,
 Buelow  e_t al.  (1979)  have shown that zinc,  iron,  and manganese  in the
 water can provide protection against asbestos release.   On the  other
 hand, mechanical handling during installation and tapping  for new users
 promote release,  if  only temporarily.   In  addition,  a high H2S  content
 in the  source water  was associated with higher levels of asbestos in
 drinking  water.

      Obviously  the release  of  asbestos from piping  is a  largely unpre-
 dictable  event.   Levels  may vary within a  system  at  different times.
 Therefore, calculating asbestos levels resulting in drinking water
would be extremely difficult.

     Liners of  concrete  pipes  can  also  be a  source of pollutants  in
 drinking water.   Tetrachloroethylene has been  reported at  levels  up to
 5 mg/1 in drinking water  in Massachusetts.   These levels were caused  by
 leaching  from a resinous  liner of  concrete pipes used in distribution
 systems (DEQE 1980).

 6.4.3  PVC Pipes

     Polyvinyl chloride  (PVC) pipe has been used in distribution  systems
 for a number of years.  Though it has not been studied extensively, PVC
pipe has generally been considered stable.  Flexible PVC, however",  has
been shown to release a number of organic materials,  including numerous


                                    6-5

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 phthalate esters (Junk et al.  1974).   In addition, Dressman and McFarren
 (1978) nave ooserved the migration of vinyl chloride from PVC into water.
 Little is known about the factors affecting such migration, but it does
 not  seem to depend  as much upon water chemistry as does the migration
 from metal pipes.


      In addition to vinyl chloride, Wang and Bricker (1979) identified
 MEK (2-butanone) and THF (tetrahydrofuran)  in a water supply after PVC
 pipes were installed.  These solvents were  used in the PVC pipe cement
 used to join the tubing.   The  concentrations in this particular case
 depended upon the residence time, up  to an  equilibrium concentration.

      Clearly too little is known at present about the release of con-
 taminants from the  PVC pipe to  describe even the conditions that promote


 6-5   ACCIDENTAL CONTAMINATION IN THE  DISTRIBUTION SYSTEM

      Accidental contamination of drinking water in the  distribution
 system may occur in a number of ways,  including cross-connections,
 back-siphonage,  and breaks  in the system.   The  contaminants that may
 result  are limitless,  and  do not depend  upon the characteristics of the
 water,  the distribution system,  or  the  chemical.   As  a  typical  example
 of what  may occur,  Craun and Gunn (1979) described an incident  in which

 Sitr?r?-        C°  a  h°me f°r  termitS  C°ntro1  had entered a water
 distribution  system due to back-siphonage.   It was hypothesized  that
 fnd  rhSl PTaratl°n  ^d  dUUti0n  °f  the solution, back-siphonage  occurred
 and  chlordane entered the distribution system.

     Obviously,  this  type of incident cannot be  predicted,  nor  can  the
 situations  in which it would occur  be described.

 6.6  SUMMARY

     Some  of the important routes of contamination in drinking water
 treatment  can be described qualitatively as  shown  in  Table  6-2.   In
 some cases  the conditions that may promote release or contamination are
known but  in no case can the estimated resulting concentrations  of
water-borne pollutants be calculated.
                                    6-6

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           TABLE 6-2.  CONTAMINATION OF DRINKING WATER IN
                       TREATMENT AND DISTRIBUTION
  Contamination Route

Treatment:

  Chemical addition


  Chemical formation


Distribution:

  Pipe Corrosion

  Cross-connection, back-
   siphonage
       Chemicals  Involved
Large number, chlorine and
fluoride common

Trihalomethanes, other chlorinated
  organics
Metals, asbestos, vinyl chloride

Unknown
                                 6-7

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                           7.0  REFERENCES
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 Distributed  by Interagency Agricultural Information Task Force; undated.

 Arguello, M.D.;  Chriswell, C.D. ;  Fritz, J.S.;  Kissinger, L.D.;  Lee,  K.W. ;
 Richard,  J.J.; Svec,  H.J.   Trihalomethanes  in  water:   a report  on the
 occurrence,  seasonal  variation in concentrations,  and precursors of
 trihalomethanes.   J.  Am. Water Works  Assoc.  71(9):504-508;  1979.

 Arthur  D. Little,  Inc.  An exposure and risk assessment for phthalate
 esters.   Washington,  DC:   Office  of Water Regulations and Standards,
 U.S.  Environmental Protection  Agency;  1981.

 Battelle  Columbus  Laboratories.   Multi-media levels of cadmium.
 Washington,  DC:  Office of Toxic  Substances, U.S.  Environmental
 Protection Agency;  1977.

 Brett,  R.W.; Calverly, R.K.  A one-year survey of  trihalomethane concen-
 tration changes within a distribution  system.   J.  Am.  Water Works Assoc.
 71(9) .-504-508; 1979.

 Brody,  S.  Bioenergetics and growth.   New York,  NY:   Hafner Publishing
 Co.;  1964.

 Buelow, R.W.;  Millette, J.R.;  McFarren,  E.F.   Field investigation of
 the performance of  asbestos-cement  pipe under  various  water quality
 conditions.  Cincinnati, OH:   Water Supply Research Division, U.S.
 Environmental  Protection Agency;  1979.

 Craun, G.F.; Gunn,  R.A.  Outbreaks  of  waterborne disease in the United
 States:  1975-1976.   J. Am. Water Works  Assoc.  71:422;  1979.

 Department of  Environmental Quality and  Engineering (DEQE).  Tetra-
 chloroethylene update.  DEQE,  Commonwealth of  Massachusetts; 1980.

 Dressman, R.C.; McFarren,  E.F.  Determination  of vinyl chloride migration
 from  polyvinyl chloride pipe into water.  J. Am. Water Works Assoc. 20(1):
 29-30; 1978.

 Food  and Drug Administration(FDA).  Compliance program evaluation.
 FY 74 total diet studies.   Washington,  DC:   Food and Drug Administra-
 Bureau of Foods; 1977.

 Hallenbeck,  W.H.; Chen, E.H.;  Hesse, 'C.S.; Patel-Manklik, K.; Wolffe,  A.H.
 Is chrysotile asbestos released from asbestos-cement pipe into  drinking
water?  J. Am.  Water Works Assoc. 70(2):97-102; 1978.

 Israelson, O.W.; Hansen,  V.E.  Irrigation principals and practices.
 3rd ed.   New York,  NY:  John Wiley  and  Sons; 1962.


                                  7-1

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 Janick,  J.;  Schery,  R.W.;  Woods,  F.W.;  Ruttan,  V.W.   An introduction
 to  world crops.   San Francisco,  CA:   W.H.  Freeman;  1969.

 Jordan,  H.E.   Industrial requirements for  water.   As cited in Heid, J.L.;
 Joslyn,  M.A.   Food processing operations.   Westport, CT:   Avi Publishing
 Co.;  1963.

 Junk,  G.A.;  Svec,  H.J.; Vick,  R.D.;  Avery,  H.J.   Contamination of water
 by  synthetic  polymer tubes.   Environ. Sci.  Technol.  8(16):1100-1106•
 1974.

 Karalekas, P.C.;  Cran,  G.F.;  Hammonds,  A.F.;  Ruan,  C.R.;  Worth,  D.J.
 Lead  and other trace metals  in drinking water in  the Boston Metropolitan
 area.  J.  New England Water  Works Assoc. 90(2):150-179;  1976.

 Kenaga,  E.E.;  Goring, C.A.I.   Relationship  between water  solubility
 soil-sorption,  octanol-water partitioning,  and  bioconcentration of
 chemicals  in  biota.   Third Aquatic Toxicology Symposium,  ASTM,  October
 1978,  New  Orleans, LA;  1978.

 McFarren,  E.F.; Buelow, R.W.;  Thurnau,  R.C.;  Gardels,  M. ;  Sorrell, R.K.;
 Snyder,  P.; Dressman, R.C.   Water quality  deterioration  in the distri-
 bution system.  Cincinnati,  OH:  Municipal  Environmental  Research
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 Peterson,  D.L.  The  Duluth experience — asbestos, water,  and  the public.
 J.  Am. Water  Works Assoc.  70(l):24-28;  1978.

 Peterson,  J.E.  Modeling the  uptake,  metabolism,  and excretion of dichloro-
 methane  by man.  J.  Am. Ind.  Hyg. Assoc. 39(l):41-47;  1978.

 Sargent, H.E.  Asbestos in drinking water.  J. New England Water Works
 Assoc. 88(l):44-57;  1974.

 Scheulpein, R.J.;  Blank, I.H.  Permeability of the skin.   Physiol. Rev.
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 Stoewsand, G.S.  In:  Graham,  H.D.   Safety  of foods.   2nd  ed.   Westport,
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U.S. Department of Agriculture (U.S.   DoA).   Agricultural statistics 1978.
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U.S. Department of Commerce.   Census  of Manufacturers.  Special  use series:
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evaluation of waterborne routes of exposure from  other than  food  and
drinking water.  EPA 440/4-79/016.  Washington, DC:  U.S.  Environmental
Protection Agency;  1979.


                               7-2

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Wang, T.-C.; Bricker, J.C.  2-butanone and tetrahvdrofuran  contamination
in the water supply.  Bull. Environ. Contain. Toxicol.  23(4-5);  1979.

Wilson, C.L.; Loomis, W.E.  Botany.  4th ed.  New York, NY:  Holt,
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Yates, J.R.  Mechanism of water uptake by skin.  Elden, H.R. ed.
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1971.
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