United States
        Environmental Protection  Office of Water          EPA 811-Z-92-002
        Agency         4601               July 1992
&EPA 40 CFR, PARTS 141 and 142
       NATIONAL PRIMARY DRINKING
       REGULATIONS; SYNTHETIC
       ORGANIC CHEMICALS AND
       INORGANIC CHEMICALS

       FINAL RULE
                                     Recycled/Recyclable
                                     Printed on paper that contains at least
                                     50% post-consumer recycled fiber

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Friday
Julv 17. 1992
Part III
             *

Environmental

Protection Agency

'40 CFR Parts 141 and 142
National Primary Drinking Water
Regulations; Synthetic Organic Chemicals
and inorganic Chemicals; Final Rule

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31776       Federal Register / Vol. 57. No. 138 / Friday. July  17. 1992 / Rules and Regulations
ENVIRONMENTAL PROTECTION
AGENCY

40 CFR Parts 141 and 142
tWH-FRL-4137-31

Drinking Water; National Primary
Drinking Water Regulations—Synthetic
Organic Chetnleat* and Inorganic
Chemicals; National Primary Drinking
Water Regulations Implementation

AGENCY: U.S. Environmental Protection
Agency (EPA).
ACTION; Final rule.	

SUMMARY: By this document, EPA is
promulgating maximum contaminant
level goals (MCLGs) and National
Primary Drinking Water Regulations
(NPDWRs) for 18 synthetic organic
chemicals (SOCs) and 5 inorganic
che'micals (lOCs). The NPDWRs consist
of maximum contaminant levels (MCLs)
for the SOCs and lOCs. The NPDWRs
also include monitoring, reporting, and
public notification requirements for
these chemicals. Regulation of sulfate,
one of the contaminants in the proposed
rule, has been deferred. This document
includes the best available technology
(BAT) upon which the MCLs are based
and the BAT for the purpose of issuing
variances.
DATES: The effective date for revisions
and additions to 5§ 141.32.141.40.141.50
(except 141.50(b)(28)). 141.51141.61
(except 141.61(c)(28)), 141.62,142.16. and
142.62 is January 17,1994. The effective
date for revisions and additions to
§! 141.2,141.6,141.12.141.23.141.24.
141.50{b](26), 141.60.141.61(c}(26), and
141.89 is August 17.1992. In accordance
with 40 CFR 23.7. this regulation shall be
considered final Agency action for the
purposes of judicial review at 1 p.m..
Eastern time on July 31.1992.
ADDRESSES: Copies of the public
comments received, EPA responses, and.
all other supporting documents
(including references included in this
notice) are available for review at the
U.S. Environmental Protection Agency
(EPA). Drinking Water Docket 401 M
Street. SW.. Washington. DC 20480. For
access to the docket materials, call 202-
260-3027 between 9 a.m. and 3:30 p.m.
Any document referenced by an MRID
number is available by contacting Susan
Lawrence. Freedom of Information
Office. Office  of Pesticide Programs, at
703-557-4454.'
  Copies of health criteria, analytical
methods, and  economic impact analysis
documents are available for A fee from
 the National Technical Information
. Service (NTIS). U.S. Department of
 Commerce. 5285 Port Royal Road.
 Springfield. Virginia 22161. The toll-free
 number is 800-338-4700. local: 703-487-
 4650. Additionally, they can be reviewed
 at the EPA regional offices listed below.
 POM FURTHER INFORMATION CONTACT: .
 Gregory Helms. Regulation Management
 Branch. Drinking Water Standards
 Division. Office of Ground Water and
 Drinking Water (WH-550D). U.S.
 Environmental Protection Agency. 401 M
 Street. SW..  Washington. DC 20460. 202-
 260-8049. or one of the EPA Regional
 Office contacts listed below. General
 information may also be obtained from
 the EPA Drinking Water Hotline. Ca.'ers
 within the United States may reach '.- .-
 Safe Drinking Water Hotline at 800-^. '.-
 4791. The Safe Drinking Water Hotlir i.
 is open Monday through Friday.
 excluding Federal holidays, from 8:30
 a.m. to 4 p.m. Eastern Time.

 EPA Regional Offices
 I. JFK Federal  Bldg.. Room 2203. One
   Congress Street, llth floor. Boston. MA
   02203. Phone: (617) 565-3810. Jerry Heaiey
 II. 28 Federal Plaza. Room 824. New York. NY
   10278. Phone: (212) 264-1800, Walter
   Andrews
 HI. 841 Chestnut Street. Philadelphia. PA
   19107. Phone: (215) 597-9600. Dale Long
 IV. 345 Courtland Street. N.E.. Atlanta. GA
   30385. Phone: (404} 347-3633, Wayne
  Aronson
 V. 77 West Jackson Boulevard. Chicago, D.
   60804. Phone: (312) 353-2000, Ed Walters
 VI. 1445 Ross Avenue. Dallas. TX 75202.
   Phone: (214) 655-7155. Tom Love
 VII. 728 Minnesota Ave.. Kansas City. KS
   66101. Phone: (913) 276-7032. Ralph
   Langemeier
 VIII. One Denver Place. 999 18th Street Suite
  500. Denver. CO 80202-2468, Phone: (303)
  293-1413. Patrick Crotty
 IX. 75 Hawthorne Street. San Francisco. CA
  94105, Phone-. (415) 744-1855, Steve
   Pardieck
 X. 1200 Sixth Avenue. Seattle. WA 96101.
   Phone: (206) 553-1225. Jan Hasting*

 SUPPLEMENTARY INFORMATION:
 Table of Contents

 Abbreviations Used in this Rule Li*t of
 Tables
 Table of Contents
       I. Summary of Today's Action
             II Background           :
   A. Statutory Authority
   B. Regulatory History
   C. Applicability               .  '..-.,
   D. Public Comments on the Proposal' "f
    III. Explanation of Today's Action
 A. Establishment of MCLGs
   1. How MCLGs are Developed
   2. Occurrence and Relative Source Con-
     tribution
   3. Inorganic MCLGs
     a. Antimony
     b. Beryllium
   .  c. Cyanide •• .'••'•'
     d. Nickel
     e. Sulfate
     f. Thallium
   4. Organic MCLGs
     a. Benzo(a)pyrene and other PAHs
     b. Dalapon
     c. Dichloromethane (Methylene chlo-
      ride)
    d. Di(2-ethylhexyl)adipate
    e. Di(2-ethylhexyl)phthalate
    f. Dinoseb
    g. Diquat
    h. Endothall
    i. Glyphosate
    j. Hexachlorocyclopentadiene (HEX)
    k. Simazine
    1.1.2.4-Trichlorobenzene
    m. 1.1.2-Trichloroethane
    n. 2.3.7.8-Tetrachlorodibenzo-p-dioxin
    o. Endrin, hexachlorobenzene. oxamyl.
      picloram
E Establishment of MCLs
  1. Methodology for Determination of
    MCLs
  2. Inorganic Analytical Methods
    a. Metals (antimony, beryllium, nickel
      and thallium)
    b. Anions (cyanide and sulfate)
    c. Method Detection Limits and  Practi-
      cal Quantitation Levels
    d. Inorganic Chemical Sample Preser-
      vation.  Container,  and  Holding
      Times
  3. Organic Analytical Methods
    a. Method-Specific Comments
    b. Responses to Comments Specific to
      Method 1613 for Dioxin
    c. Detection and  Quantitation Levels:
      Laboratory Performance Criteria
  4. Laboratory Certification
  5. Selection of Best Available Technolo-
    gy
    a. Inorganics
    b.  Synthetic  Organic   Contaminant
      MCLs
  6. Determination of MCLs
    a. Inorganic Contaminant  MCLs
    b.  Synthetic  Organic   Contaminant
     MCLs
C. Compliance Monitoring Requirements
  1. Introduction
  2. Effective Date
  3, Standard Monitoring Framework
    a. Three-, Six-. Nine-Year  Cycles
    b. Base Monitoring Requirement!
    c. Volatile Organic'Chemicals (VOCs)
    d. Increased Monitoring
    e. Decreased Monitoring
    f. Vulnerability Assessments
    g. Relation to the  Wellhead Protection
     (WHP) Program

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             federal Rcsitter  /  Vol. 57.  Mo. t3& /Friday. }uly 17. 1992 / Rules and Regidationa
     h. Ground Water Policy
     1. Initial and. Repeat Base Monitoring
   4. Monitoring Frequenciei
     a. Inorganics
       (1) Initial and Repeat Base Require-
         ments  .
       (2) Increased Monitoring
       (3) Decreased Monitoring
     b. Cyanide
     c.   Volatile  Organic.  Corrtaminantr
       (VOCs)
       (1) Initial and Repeat Base Require-
         ments
       (2) Increased Monitoring
       (3) Decreased Monitoring
     d.    Synthetic  Organic   Chemicals
       (SOCs)
       (1) Initial and Repeat Base Require-
         ments
       (2) Increased Monitoring
       (3) Decreased Monitoring
     e. Sulfates
    5. Other Issues
     a. Compliance Determinations
     b. Confirmation Samples
     c. Compositing
     d.   Polynuclear Aromatic   Hydrocar-
       bons (PAHs)
  D. Variances and Exemptions
    1. Variances
    2. Exemptions
    3. Point-of-Use  Devices. Bottled Water.
     and Point-of-Entry Devices
    4. Public Comments
  E. Public Notice Requirements
    1. General Comments
    2. Contaminant-Specific Comments
  F. Secondary MCL for Hexachlorocyclc-
    pentadiene
  C. State Implementation
    1. Special State  Primacy  Requirements
    2. State Recordkeeping Requirements
    3. State Reporting Requirements
IV. Economic Analysis
  A. Costs of  the Final Rule
  B. Comparison  to Proposed Rule
    1. Monitoring Requirements
    2. Changes In MCLs
    3. Changes in Occurrence Data
    4. Changes in Unit Treatment Cost Esti-
      mates
  C. Cost to Systems
  D. Cost to State Programs
V. Other  Requirements
   A. Regulatory Flexibility Analysis
   B. Paperwork Reduction Act
   C. Federalism Review
VI. References.
Abbreviation* U*od In This Rula
AA; Direct Aspiration Atomic Absorption
     Spectroscopy
ACS: American Chemical Society
ADI: Acceptable Daily Intak*
- ASDWA; Association of State Drinking
     Water Administrators
ASTM: American Society for Testing
     Materials
 BAT: Best Available Technology
• BTCA: Best Technology Generally Available
 CRAVE: Oncer Risk Assessment
     Verification  Enterprise
 CAAj Clean Air Act.
 CAG: Cancer Assessment Group
CUR: Carbon Usage Rate
CWS: Community Water System
DWEL: Drinking Water Equivalent Level
EBCT: Empty Eled Contact Time
ELA: Economic Impact Analysis
EMSL Environmental Monitoring Systems
    Laboratory (Cincinnati)
EPA: Environmental Protection Agency
FDA: Food and Drug Administration
Fit Federal Register  •
GAC: Granular Activated Carbon
GFAA: Graphite Fumance Atomic
    Absorption Spectroscopy
HPLC: High Pressure Liquid Chromatography
HSDB: Hazardous Substances Data Base
ICP-AES: Inductively Coupled Plasma-
    Atomic Emission Spectroscopy
IE: Ion Exchange
IMDL: Inter-Laboratory Method Detection
    Limit
IOC: Inorganic Chemical
IRIS: Integrated Risk Information System
LOAEL- Lowest-Observed-Adverse-Effect
    Level
LOQ: Limit of Quantitation
MCAWW: Methods for Chemical Analysis of
    Water and Wastes
MCL: Maximum Contaminant Level
    (expressed as mg/1)1
MCLG: Maximum Contaminant Level Goal
MDL: Method Detection Limit
MF: Modifying, Factor
MGD: Million Gallons per Day
NAS: National Academy of Sciences
NCWS: Non-Community Water System
NIPDWR: National Interim Primary Drinking
    Water Regulation
NOA: Notice of Availability
NOAEL: No-Observed-Adverse-Effect Level
NOEL: No-Ob:ierved-Effect Level
NPDES: National Pollution Discharge
    Elimination System
NPDWR: National Primary Drinking Water
    Regulation
NTIS: National Technical Information Service
NTNCWS: Non-Transient Non-Community
    Water Syiitem
O&M: Operations & Maintenance
OPP: Office of Pesticide Programs
ORD: Office of Research and Development
OW: Office of Water
OX: Oxidation (Chlorine or Ozone)
PAC: Powdered Activated Carbon
PAHs: Polynuclear  Aromatic Hydrocarbons
Pathco: Pathology Working Group
 PE: Performance Evaluation
 POE: Point-of-Entry Technologies
 POU: Point-of-Use Technologies
 PQU Practical Quantitation Level
 FT A: Packed Tower Aeration
 PWS: Public Water System
 RCRA; Resource Conservation Recovery Act
 RfC: Reference Concentration
 RfD: Reference Dose (formerly termed
     Acceptable Daily Intake (ADI))
 R1A; Regulatory Impact Analysis
 RMCL: Recommended Maximum
     Contaminant Level
 RO: Reverse  Osmosis
 RSC- Relative Source Cootributiin
 SOW A: Safe Drinking Water Act or the
     "Act" at amended in 19*8
SMCL: Secondary Maximum Contamir
    Level
SMF: Standardized Monitoring Framev
SOC: Synthetic Organic Chemical
T&C: Technology & Costs
TEF: Toxic Equivalency Factors
TEM: Transmission Electron Microscop
TWS: Transient Non-Community Wate
    System
UF: Uncertainty Factor-   ;;  •    -
UIC: Underground Injection Control
USDA: U.S. Department of Agriculture
VOC: Volatile Organic Chemcial
WHP: Wellhead Protection
WHPA: Wellhead Protection Area
WS: Water Supply
  11.000 micrograms (ng) = l milligram

List of Table*
Table 1—MCLGs and MCLs for Inorgai
    Contaminants
Table 2—MCLGs and MCLs for Organi
    Contaminants
Table 3—Best Available Technologies
    Remove Inorganic Contaminants
Table 4—Best Available Technologies
    Remove Synthetic Organic Contarr
Table 5—Compliance Monitoring
    Requirements
Table 6—Analytical Methods for Inorg.
    Chemicals
TaWe 7—Analytical Methods for Vola!
    Organic Chemicals
Table 6—Analytical Methods for Pestic
    SOCs
Table 9—Laboratory Certification Crite
Table 10—EPA's Three-Category Appr
    for Establishing MCLGs
Table 11—Approved Methodology for
    Inorganic Contaminants and Meth-
    Detection Limits (MDLs)
Table 12—Inorganic Contaminant
    Acceptance Limits and Practical
    Quantitation Levels
Table 13—Inorganic Contaminant Sam)
    Preservation. Container, and Holdi
    Time Requirements
Table 14—Analytical Methods. DetectH
    Limits.  MDLs. PQLs. MCLs. and MC
    for Organic Chemicals
Table 15—MCLs. PQLs and Acceptance
    Limits Determined from Laboratory
    Performance Studies
Table 18—Final BAT for Inorganic
    Contaminants
Table 17—Proposed and Final BAT for
    Organic Contaminants
Table l&—MCL Analysis for Category 1
    Synthetic Organic Contaminants
Table 19—MCL Analysis for Category I
    HI Synthetic Organic Contaminant!
Table 20—Section 1415 BAT for Inorgat
    Compounds
Table 21—Section 1415 BAT for Organi.
    Compound*
Table 22—Summary of Cost Estimate* I
    Final Rul*
Table 23—Summary of Benefit* Estimat
    Final Rule
Table 24—Comparison of Costs for Pro;
    and Final Rule*

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JITTt
/ VoL 57, No. 138 / Friday. July 17. 1992 / Rufcs nod Regulation.
Tabk 25—Increased Coat of Compliance In
   Selected System Size Categories

I. Summary of Todiy'i Action
                            TASL£ 1.—MCLGS AND MCLS FOR INORGANIC CONTAMINANTS
Cnsmcal
(1) Antimony ,„,„„,..,.. 	 , 	 .....,, ....... _,, 	 	 	 	 ,
I2J 8a*yiMtv 	
i3) Cy«nm 	 ,,. .,. _____ 	 	 ._ ,.., 	 	
(4) N«l«tl™, 	 .... , 	 , 	 	 	 	
(5) Sotlate ._,.. 	 	 	 	 	 	 	 	
(6) Thallium 	 	 _ 	 	 ,._,_,

1 ProoOMd
j MCLG».

0.006
0004
0.2
0.1
0«f*rrod

Propoowo
• MOJ cfiicroettiar>« _..,„. 	 _.,...__ 	 „ 	 „ 	
1 .2.4'TncNorOfjen.iene .„._._._,„,., 	 	 	 	 	 _ .
1.1J2*Tr>criioroetiw>e 	 ._ 	 	 	 	
Dm Don 	 ... ..._,,
Dtnoub
fVy^it
E«x3otha)f . ........... .
Enorm , 	 „...._„_.... 	 . 	 	 	 ,
Glypr«saie
Onamyt (Vydatfl) 	 	 	
P*c*e)ryl}pMhalaIt
Hexacr*5rc*en»r>e, 	 	 	 	
2.3.7 J-TCOO (Ooan) .__ 	




1
'
	 	 1

	 ' "i
	 '" 	 """]






	 	 . . |
.. _ . j
... — 	 	 .j
MCLGa (mg/
7orf*

0.003



0 002





0 5

2wo
0.05

Final
MCLGo (mg/
0


0.003











2en»
0.05

MCU (mg/

0.005
0.009
0.005
0.2
0.007
0.02
0.1

0.7
0^
0.5
0.001


aoci
0.05 '

Final
MCU (mg/
I)

0.005
0.07
0.005
0,2
•3.007
0.02
0.1
0.002
0.7
0.2
0.5
0.004
0.0002

0.006
a 001
0.05

                   TA8t£ 3—BasT AVAILABLE TECHNOLOG^S To REMOVE INORGANIC CONTAMINANTS

Irvorgartc contaminant

Bwyiixxn.., _. 	 	
Cysmoe.. — ... 	 	 	 	 	
N(ckei,..._....__._.,..
TIMWiom ,™......» 	 _„ 	 	 	 	 	 __

Activated
alumn*

X

X

CoagLirt.cn/
fcraecx.
X
X


B«*t <
Urn*
»or>anne>

X
^

va4*M« toc.vx>k
ion ochcng*

X
X

X
5g«*
Reverse
osnosi*
X
X



Chtooo*
oxidation



	 : 	

Bectrodaty
«•

	


   ' Not 1415 BAT «or unaf ffOtnt for variance* ortes* treatment • curenOy n ptac*.

               TABLE *-!BEST AVAILABLE TECHNOLOGIES To REMOVE SYNTHETIC ORGANIC COWTAMJNAKTS
Chenwal
VOCa:
OcMoromemane , 	 ..
1i.4.Tnef>loro<>weeo» 	 	 	
1.1.2-Tnchkxoeiftane 	 	 _ .. _.. '•
PMCOEtee: . . 	
DA^An^^ . *~
a««-h . 	
Diouat,. _ 	 	
FrWrfhrf , 	 ,
crtorin... 	 tt lrt 	
Glyprvouta.. 	 „ 	 "
Oxim/t (Vyct«te)__ 	 ._._.. 	 . 	 . 	 _._ 	 	
ftcloram 	 ™™7IL'_Z 	 !_ 1_ 	
GAC'

j(

X
X
X
X
. X
_
X
PTA»




	
ox«




X

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               Federal Register /  VoL 57,  No. 138 /  Friday.  July 17, 1992  / Rules  and  Regulations
31779
             TABLE 4—BEST AVAILABLE TECHNOLOGIES To REMOVE SYNTHETIC ORGANIC CONTAMINANTS—Continued
                                            Chemical
                                                                                                    GAC'
                                                                                                                 PTA«
                                                                                                                               OX'

Omer Organic Contammarits:




237 8-TCDD (Dtoxin) ..." 	









X
X
X
x
. X
X
X



X


X










    ' GAC = Granular activated carbon.
    » PTA = Pacned tower aeration.
    •• OX = Oxidation (Chlorine or Ozone).
                                       TABLE 5.—COMPLIANCE MONITORING REQUIREMENTS *
      Contaminant
                                       8as« requirement
                             Ground water
                                                    Surface water
                                                                       Trigger that increase* monitoring
                                                                                                                  Waivers'
4 inorgarxs	  1 Sample/3 years...	 Annual sample	  MCL—	  Yes. based  on analytical result* of 3
                                                                                                      rounds.
                              1 Sample/9 years after 3 samples < MCL
Cyarwde	_	  1 Sample/3 years	_ Annual sample..:	  >MCt	,	'.		  Yes. based on vulnerability assessment.
                              1 Sample/9 years after 3 sample* CAL METHODS FOR
PESTJCtDES/SOCS
EPA rrwtftods
505
506
507
soe
515.1
531.1
1613
547
54*
549
550/560,1
Contamirtants
Endrin.
Simazine.
Di (2-e4hytt^e3ryf) adip*i*.
Di (2-ethy«>*xy() prtlTiaiat*.
Simazin*.
Endhn.
Datapon,
Dinoeeb.
Picloram.
Oitamvl (V/d***).
2.3.73-TCOO (Otoar^.
GrfphOMtil.
EndoJh*.
DiquK.
Benzo (a) pvn»n*.
TABLE 8.— ANALYTICAL METHODS FOR
PESTtctOES/SOCs— Continued
EPA 'method*
•525.1
•Contaminants
Benzo(a) pyren*.
DI (2-ethyfhexyO aolpate.
01 <2-ethylhe*yf) phthalat*.
Endhn.
Hexachlorobenzen*.
HexachkxocyclopentarJeri*.
Simazin*,
' MeO»a525.1maY be
mfofrnstiofv.
TABLE 9.— LABORAT
ORTT
/OCt
Antimony_
BeryaSum._
Cyanide
Nick*
The*um
VOCK
SOCf





At other SOC*
used i adequate sensrtivi-
Section 1KB for addttonal
ORY CERTIFICATJON
ER1A
±30% £ 0.006 mg/L
±15% S 0.001 mg/L
±25% £ 0.1 mg/L
±15% £ 0.01 mg/t
±30% £ 0.002 mg/l
±20% £ 0.01 rng/t
±40% < 0.01 mg/L
±30%.
2 xandert de*«*«on«
band on study


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3178ft
/ VoL 57. No. 138 / Friday. July 17.  IflCZ / Raks  and Regulation*
II. Background
A. Statutory Authority
  These regulations are among a
continuing aeries of rules mandated by
the 1988 Amendments to the Safe
Drinking Water Act. As this final rule
demonstrates. EPA is committed to
effective implementation of the laws   .
established by Congress-It should be
noted that EPA's development and
promulgation of these rules is now being
coordinated with a number of other EPA
activities intended to ensure protection
of public health while responsibly
addressing the economic challenge of
the ever-growing list of regulatory
requirements on States and water
systems. To the extent that the results of
this coordination call for change in the
law. we will make that known to the
Congress. It is a commitment of EPA.
however, to understand where
legitimate local implementation
concerns exist.
  EPA is working with a recently
convened Governors' Forum on
Environmental Management that is
reviewing means to ensure health
protection while balancing the need for
State regulatory flexibility to address
the States' highest priorities with
available resources. EPA'i
Environmental Financial Advisory
Board Is developing alternative
financing mechanisms with particular
attention on small community concerns.
In addition. EPA is in the third year of
an initiative to identify and promote
low-cost solutions to drinking water
protection. These include consolidation
of water systems to spread costs over a
larger consumer base:  pooling of several
systems' water samples to reduce
monitoring cost and low-cost treatment
 technologies that can cut water bills in
 very small water systems to as much as
 one-half what might arise with
 traditional engineering solutions.
   In addition. EPA is considering greater
 reliance on risk-based priority-setting
 within State compliance programs. That
 approach would focus limited State and
 Federal resources on those elements of
 the public water supply supervision
 program having the greatest potential
 for reducing risk and promoting public
 health protection. Again, EPA would
 only take action in this area to the
 extent consistent with law.
   The Safe Drinking Water Act (SDWA
 or "the Act"), as amended in 1988 (Pub.
 L 99-339,100 Stat 642}, requires EPA to
 publish "maximum contaminant level
 goals" [MCLGs] for contsmininti which,
 in the Judgment of the Administrator,
 "may have any adverse effect on the
 health of person* end which {are]
 known or anticipated to occur in public
       water systems" (section 1412(bK3MA)).
       MCLGs are to be set at a level at which
       "no known or anticipated adverse
       effects on the health of persons occur
       and which allows an adequate margin of
       safety" (section 1412(b)(4)).
          At the same time EPA publishes an
       MCLG. which is a non-enforceable
       health goal, it must also promulgate •••>'•'
       National Primary Drinking Water
       Regulation (NPDWR) which includes
       either (1) a maximum contaminant level
       (MCL). or (2) a required treatment
       technique (section 1401(1), 1412(a)(3).
       and 1412(b)(7)(A)). A treatment
       technique may be set only if it is not
       "economically or technologically
       feasible" to ascertain the level of a
       contaminant (Sections 1401(1) and
       1412(b)(7)(A)). An MCL must be set as
       close to the MCLG as feasible (section
       1412(b)(4)). Under the Act. "feasible"
       means "feasible with the use of the best
       technology, treatment techniques and
       other means which the  Administrator
       finds, after examination for efficacy
       under field conditions and not solely
       under laboratory conditions (taking cost
       into consideration)" (section 1412(b)(5}).
       In setting MCLs. EPA considers the cost
       of treatment technology to large public
       water systems with relatively clean
       source water supplies (132 Cong. Rec.
       S6287 (daily ed.. May 21.1986)).1 Each
       NPDWR that establishes an MCL must
       list the best available technology,
        treatment techniques, and other means
       that are feasible for meeting the MCL
       (BAT) (section 1412(b)(6)). NPDWRs
       include monitoring, analytical and
        quality assurance requirements,
        specifically, "criteria and procedures to
        assure a supply of drinking water which
        dependably complies with such
        maximum contaminant levels * *  * "
        (section 1401(1)(D)}. Section 1445 also
        authorizes EPA to promulgate
        monitoring requirements.
          Section 1414{c) requires each owner or
        operator of a public water system  to
        give notice to persons served by it of (1)
        any failure to comply with « maximum
        contaminant level, treatment technique,
        or testing procedure required by a
        NPDWR: (2) any failure to comply with
        any monitoring required pursuant  to
        section 1445 of the Act; (3} the existence
        of a variance or exemption; and (4) any
        failure to comply with  the requirements
        of any schedule prescribed pursuant to «
        variance or exemption.
          Under the 1986 Amendments to  the
        SDWA, EPA was to complete the
        promulgation of NPDWRa for 83 listed
        contaminants, in three  phases, by  fooe
        19,1989. After 1969, an additional  23
          1 EPA 
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             Federal
/ VoL 57, No.  13* / Friday, July 17. 199* / Rules and
                                                                                                           31781
 standards is specifically required und«r
 the SDWA for 22 of the 23 contaminants
 in today's rule [see SDWA section
 1412(b](l), 42 U.S.C. 300g-l(bKl)].
 Hexachlorobenzene. although not on the
 statutory list of contaminants to be
 regulated, is being regulated because it
 has.been found in drinking, water and-
 may cause adverse human health
 effects.

 C. Applicability
  The MCLs promulgated by today's
 rule apply to all community and non-
 transient non-community PWS.

"U. Public Comments on the Proposal
  EPA requested comments on all
 aspects of the July 25,1990 proposal A
 summary of the major comments and the
 Agency's response to the issues raised
 are presented in the following section.
 The Agency's detailed response to the
 comments received are presented in the
 document "Response to Comments
 Received on the Proposed Requirements
 for 24 Contaminants of July 25,1990 and
 Notice of Availability of November 29,
 1991," which is in the public docket for
 this rule.
  EPA received approximately 138
 comments on the proposed MCLGs and
 MCLs in the July 1990 proposal. These
 comments represented the views of 66
 industrial/commercial groups, 25 State
 governments, 36 local governments and
 public water systems, 2 public interest
 groups, 3 Federal agencies, as well as
. comments from individual citizens and
 academic interests.
   EPA held a public hearing on the
 proposed rule September 25,1990 in
 Washington, DC. Six individuals
 representing three organizations made
 oral presentations at the public bearing.
 A transcript of the hearing is available
 in the docket [USEPA. 1990J].
   EPA published a Notice of
 Availability (NOA) on November 29.
 1991 for public review and comment on
 new information received by the Agency
 and analyses of the information, which
 was being considered in establishing
 final regulations for these contaminants.
   EPA received approximately 34
 comments on the NOA. Thete comments
 represented the views of 14 industrial/
 commercial groups, 10 State
 - governments, and 10 local governments
 and public water systems.
' m. Explanation of Today's Action

 A. Establishment of MCLGs
   Most of the MCLGs promulgated
 today are at the same level as proposed
 in July 1990, However, the MCLGt far
 antimony, beryllium, skruudne, di(2-
 ethylhexyljadipate and 1.2,4-
        trichlorobenzene are different from
        those proposed in that notice. Changes
        result from public comments and/or new
        information received by the Agency. The
        change in the MCLG for antimony is due
        to a revaluation of the relative source
        contribution based on public comments.
        The change in UM MCXG forberyllium is .
        due to « reevataatioa of its   •
        categorization for setting the MCLG (i.e..
        EPA revised its classification from
        Category I to Category II based on
        public comments and revaluation of the
        data). The MCLGs for simazine, di(2-
        ethylhexyl)adipate arid 1.2.4-
        trichlorobenzene changed because new
        health information became available for
        these three compounds since the July
        1990 proposal. The new health data and
        other information pertinent to this rule
        was made available to the public for
        review and comment in the November
        1991 NOA {56 FR 60949}. A full
        explanation of these changes is included
        below in the sections for each specific
        contaminant. The draft health criteria
        documents prepared in support of the
        proposed  niles have all been finalized
        and placed in the public docket and
        through NTIS, with the exception of
        documents for dioxin and sulfate. Dioxin
        is being regulated bailed on the
        information in the draft criteria
        document pending Agency review of
        dioxin health effects. Regulation of
        sulfate has been deferred.
          Most of the MCLs promulgated today
        are at the same level as proposed in
        July. 1990. The MCL for thallium, for
        which options of 0.002 mg/1 and 0.001
        mg/1 were proposed, is being finjli**d
        as 0.002 mg/L Based on additional
        analytic chemistry data presented in die
        NOA. the proposed dioxin MCL of
        SxlQ-'mg/l is being reduced to 3xlO~*
        mg/1 in this final rule. The MCLG and
        MCL for sulfate are being deferred
        pending further study. The fnstificanon
        for this action is discussed in section
        IH.B.5 of this notice. Sulfate will b*
        addressed in a future action.
          In today's rule. EPA is responding to
        the major issues raised by the public in
        reference to the July 1990 proposal [55
        FR 30370] and the November 1991 NOA
        [56 FR 60949]. For EPA's complete
        response  to all issues raised in
        comments on both the July 1990 and
        November 1991 notic«s, EPA refers the
        reader to  the Comment/Response
        Document found in the Phase V docket
        '[USEPA, 1992a],
        1. How MCLGs Are Developed
          MCLGs are set at concentration levels
        at which no known or anticipated
        adverse health effects occur, allowing
        for an adequate  margin of safety.
        Establishment of an MCLG for each
specific contaminant depends on the
evidence of carcinogenitity from
drinking water exposure or the Agency's
reference do*e (RID) based on
noncarcinogeriic data.
  The cancer classification for a specific
chemical and the reference dose are
adopted by two. different Agency group*.
Decisions on cancer classifications are
made by the Cancer Risk Assessment
Verification Endeavor (CRAVE) Work
Group, which is composed of
representatives of various EPA program
offices. Decisions on EPA RfDs (using
non-cancer endpoints only) are made
through the Agency RfD/RfC work
group, also composed of representatives
of various EPA program offices.
Decisions by CRAVE and the RfD/RfC
groups represent consensus on risk
assessments for the Agency and can be
used by the respective regulatory
programs as the basis for regulatory
decisions. Summaries of the decisions
by these two groups  are published in the
Agency's Integrated Risk Information
System (IRIS). This system can be
accessed by the public by contacting
Mike McLaughlin of DIALCOM, Inc. at
202-488-0550.
  The RfO (expressed in mg/kg/day) is
aa estimate, with uncertainty spanning
perhaps an order of magnitude, of a
daily exposure to the human population
         sensitive subgroups) that is
likely to be without an appreciable risk
of deleterious health effects during a
lifetime. The RfD is derived from a no-
or lowest-observed-adverse-effect level
(called a NOAEL or LOAEL.
respectively) that has been identified
frora a sobchronic or chronic scientific
study of humans or animals. The
NOAEL or LOAEL ts then dirid«d by
uncertainty factors) to derive the RfD.
  Uncertainty factors are u«ed in order
to estimate the comparable "no-effect"
level for a larger heterogeneous human
population. The use of uncertainty
factors accounts for intra- and inter-
spedet variability, the small number of
animals tested compared to the size of
the population, sensitive subpopulations
and the possibility of synergistic action
between chemicals (see 52 FR 25600 for
further discussion OB the use of
uncertainty factors).
  The us* of an uncertainty factor (UF)
is important in the derivation of the RfD.
EPA has established certain guidelines
(shown below) fo determine how to
apply uncertainty factors when
establishing an RID [USEPA. 1966).

Uncazteimry Factors (UFsi
  • Use a 1- to W-feW factor when
extrapolating front vtHd experimental
       from ctadies osing prolonged

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31782       Federal RegUtw / Vol 57. No. 138  / Friday. July 17. 1992 / Rulea and Regulations
exposure to average healthy humans.
This factor is intended to account for the
variation in sensitivity among the
members of the human population.
  • Use an additional 10-fold factor
when extrapolating from valid results of
long-term studies on experimental
animals when results of studies of
human exposure are not available or are
inadequate. This factor is intended to
account for the uncertainty in
extrapolating animal data to the case of
humans.
  • Use an additional 10-fold factor
when extrapolating from less than
chronic results on experimental animals
where there are no useful long-term
human data. This factor is intended to
account for the uncertainty in
extrapolating from less than chronic
NOAELs  to chronic NOAELs.
  • Use an additional 10-fold factor
when denving a RfD from a LOAEL
                            instead of a NOAEL. This factor is
                            intended to account for the uncertainty
                            in extrapolating from LOAELs to
                            NOAELs.
                              An additional uncertainty factor may
                            be used according to scientific judgment
                            when justified.,..
                              • Use professional judgment to
                            determine another uncertainty factor
                            (alao called a modifying factor. MF) that
                            is greater than zero and less than or
                            equal to 10. The magnitude of the MF
                            depends upon the professional
                            assessment of scientific uncertainties of
                            the study and data base not explicitly
                            treated above. e.g., the completeness of
                            the overall data base and the number of
                            species tested. The default value for the
                            MFisl.
                              From the RfD, a drinking water
                            equivalent level fDWEL) is calculated.
                            The DWEL represents the drinking
                            water lifetime exposure at which
                             adverse health effects are not expected
                             to occur over a lifetime. The DWEL is
                             calculated by multiplying the RfD by an
                             assumed adult body weight (generally 70
                             kg) and then dividing by an average
                             daily water consumption of 2 liters per
                             day [NA&.1977], The DWEL assumes" • •
                             the total daily exposure to a substance
                             is from drinking water exposure. The
                             MCLG is determined by multiplying the
                             DWEL by the percentage of the total
                             daily exposure expected to be
                             contributed by drinking water, called
                             the relative source contribution.
                             Generally, EPA assumes that the
                             relative source  contribution form
                             drinking water is 20 percent of the total
                             exposure, unless other exposure data for
                             the chemical are available [see 54 FR
                             22089 and 56 FR 3535]. The relative
                             source contribution may be as high as 80
                             percent. The calculation below
                             expresses the derivation of the MCLG:
RfD


DWEL  -
      NOAEL or  LOAEL
uncertainty factor(s)

 	RfD x body  weight	
 daily  water  consumption  in  I/day
MCLG  -  DWEL  x  drinking water contribution
           (rounded  to  one significant figure)
ttg/kg  body  weight/day  (1)


                  ng/1          (2)


                  - mg/1       (3)
  For chemicals suspected to be
carcinogenic to humans, the assessment
for non-threshold toxicants consists of
the weight of evidence of
carcinogenicity in humans, using
bioassays in animals and human
epidemiological studies as well as
information that provides indirect
evidence (i.e., mutagenicity and other
short-term test results). The objectives
of the assessment are (1) to determine
the level or strength of evidence that the
substance  is a human or animal
carcinogen and (2) to provide an
upperbound estimate of the possible risk
of human exposure to the substance in
drinking water. A summary of EPA's
general carcinogen classification
scheme is (USEPA. 1986]:
  Group A—Human carcinogen based
on sufficient evidence from
epidemiological studio*.
  Croup Bl—-Probable human
carcinogen based on limited evidence of
carcinogenicity in human*.      ;
  Group A?—Probable, human  .
carcinogen based on a combination of
                            sufficient evidence in animals and
                            inadequate data in humans.
                             Group C—Possible human carcinogen
                            based on limited evidence of
                            carcinogenicity in animals in the
                            absence of human data.
                             Group D—Not classifiable based on
                            lack of data or inadequate evidence of
                            carcinogenkity from animal dat*.
                             Group E—No evidence of -
                            carcinogenicity for humans (no evidence •
                            for carcinogenicity in at least two
                            adequate animal testa in different
                            species  or in both epidemiological and
                            animal studies).
                             EPA follows a three-category
                            approach in developing MCLG* for
                            drinking water contaminant* (Table 10).
                              TABLE 10.—EPA'a THREE-CATEGORY
                             APPROACH FOR ESTABLISHING MCLGs
                             C«t«gory
Evidtne* of
      *yvi*
                                     Strong «vid«oco
                                      ofwmtenc*,
                                      pottncyand
                                      •XpOttflL
                                     UmiUd «vti*nc*
                                      cexwdtring w«ght
                                      of «vi4tnc*.
                                      ptwmecokinetic*.
                                      potency and
                                      •xpoaure.

                                     Inacfcqutt* or no
   MCLG
  •pproAch
                                                    Zero.
RfD approach
 ufetjr margn
 oil to to or
 W» 10 W»
                                                                  Each chemical 1* evaluated for
                                                                evidence of caranegenicity via
                                                                ingestioB. For volatile contaminant*,
                                                                inhalation data should also be
                                                                considered. EPA take* Into.
                                                                consideration the overall weight of '
                                                                evidence for carcinogenicity,

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              Federal Register / Vol. 57. No. 138 / Friday. July 17. 1992 / Rulei and Regulations
                                                                    91763
 pharmacokinetics. potency and
 exposure.
   EPA's policy is to set MCLGs for
 Category I chemicals at zero. The MCLG
 for Category II contaminants is
 calculated by using the RfD approach
 with an added margin of safety to
 account for possible cancer effects. If
 adequate data are not available to  •. .
 calculate an RfD, the MCLG is based on
 a cancer risk range of 10"5 to 10"*.
 MCLGs for Category III contaminants
: are calculated using the RfD/DWEL
 approach.
   The MCLG for Category I
 contaminants is set at zero because it is
 assumed, in the absence of other data,
 that there is no known threshold for
 carcinogenicity. Category I
 contaminants are those for which EPA
 has determined that there is strong
 evidence of carcinogenicity from
 drinking water. In the absence of other
 data (e.g.. oral) on the potential cancer
 risk from drinking water ingestion.
 chemicals  classified as Group A or B
 carcinogens are generally placed in
 Category I.
   Category II contaminants include
 those contaminants which EPA has
 determined that there is limited
 evidence of carcinogenicity from
 drinking water considering weight of
 evidence, pharmacokinetics, potency
 and exposure. In the absence of
 ingestion data, chemicals classified by
 the Agency as'Group C chemicals are
 generally placed in Category II. For
 Category II contaminants, two
 approaches are used to set the MCLG:
 Either (1) setting the MCLG based upon
 noncarcinogenic endpoints of toxicity
 (the RfD) then applying an additional
 safety factor of 1 to 10. or (2) setting the
 MCLG based upon a theoretical lifetime
 excess cancer risk range of 10"5 to 10"*
 using a conservative mathematical
 extrapolation model. EPA generally uses
 the first approach: however, the second
 approach is used when valid
 noncarcinogenic data are not available
 to calculate an RfD and adequate
 experimental data are available to
 quantify the cancer risk.
   EPA requested comment on tha
 appropriateness of these approaches for
 establishing MCLG* in the July 25.1990
 proposal (see 55 FR 30404-05). Two
 comments were received on this issue.
 One commenter stated.that the MCLGs
 and the MCLs should be set at level*
 able to protect against carcinogenic risk.
 The other commenter stated that Group
 C contaminants are not suitable for
 evaluation by EPA's cancer risk
; assessment process, tnd supported  •
 EPA's use of non-cafcinogqsic data for -
 establishing the MCLG foe these .
 chemicals, EPA believes that the present
approach for Category II contaminants
is protective of non-cancer effects as
well as potential carcinogenic risk.
Therefore, because adequate non-
carcinogenic data are available, the
MCLGs promulgated today for Category
II contaminants (beryllium. di(2-
ethylhexyljadipate. simazine and 1,1.2-
trichloroethane) us« the first optioru Lei.
they are based on the RfD with an
application of an additional safety
factor.
  Category III contaminants include
those contaminants for which there is
inadequate evidence of carcinogenicity
from drinking water. If there is no
additional information to consider.
contaminants classified as Group D or E
chemicals are generally placed in
Category III. For these contaminants, the
MCLG is established using the RfD
approach.

2. Occurrence and Relative Source
Contribution
  Most of the comments received on
occurrence/exposure and relative .
source contribution (RSC) were related
to current EPA policy. The Agency has
addressed many of tile questions raised
by these commenters in the Comment
Response Document for this rule. Below
is a summary of the major issues raised
and EPA's response.
  EPA received some comments
questioning the need to regulate a
chemical if there are little occurrence
data available, if the chemical occurs
infrequently or at low levels, or if the
RSC is below 20 percent. The Agency
has the statutory mandate, under
Section 1412 of the SDWA, to regulate
contaminants "which are known or
anticipated to occur in public water
systems." The  Agency believes that the
contaminants in today's rulemaking  •
have either been found or potentially
may occur in public water supplies and
that they may pose a health risk to
consumers. Also, development of
drinking water standards is specifically
required under the Safe Drinking Water
Act (SDWA) for 22 of the 23
contaminants in today's rule (see SDWA
Section 1412(b)(l), 42 U.S.C. 300g-
  Several commenters questioned why
EPA was regulating hexachlorobenzene,
since it is not on the list of 83
contaminants nor on the Drinking Water
Priority List (DWPL),,
Hexachlorobenzene. although neither on
the statutory list of contaminants to be
regulated nor on tha DWPL, is being
regulated because it has b««n found in
drinking water and may cause adverse
human health effectii.
  As described in tht background
occurrence document for
 hexachlorobenzene {USEPA, 1989bj. it
 has been widely detected in water
 albeit at low levels. Of 1.053
 observations of ground water in
 STORET. 1.028 samples had detectible
 (although not quantifiable) levels of
 hexachlorobenzene. In surface water
 STORET samples. 48 of 54 samples ha I
. detectible (although not quantifiable}"   -.-
 levels of hexachlorobenzene. The
 potential for hexachlorobenzene
 occurrence in public water supplies is
 corroborated by more recent
 information reported in EPA's "National
 Survey of Pesticides in Drinking Water
 Wells" {USEPA. 1990i], which detected
 hexachlorobenzene in several samples
 and projected that 470 PWS wells (range
 61-1.630 wells)  may have detectible
 levels (the minimum reporting limit for
 the NPS was 0.060 jig/1). EPA therefore
 believes that although levels may be
 low. there is ample evidence to conclude
 that hexachlorobenzene is known or
 anticipated  to occur in public water
 systems as required by the SDWA.
   Several comments were received on
 the current policy related to the use of a
 20 percent floor  and 80 percent ceiling
 for the RSC in setting the MCLG.  Some
 commenters objected to using a 20
 percent floor and 80 percent ceiling for
 the RSC when actual data are available
 and suggested percent contributions
 above or below  these levels. Others
 suggested using  an RSC of less than 20
 percent if available data indicate a
 drinking water contribution below this
 percentage,  assuming 100 percent
 contribution from drinking water  in the
 absence of data, and assuming 50
 percent contribution from inorganics
 and some pesticides in the absence of
 data.
   The Agency continues to believe the
 20 percent floor  and 80 percent ceiling
 are prudent and protective of public
 health. The 20 percent floor represents a
 level below which additional
 incremental protection is negligible. In
 addition, below  20 percent RSC from
 water is a dear  indication that control
 of other more contaminated media will
 result in a significantly greater reduction
 in exposure. EPA believes the 80 percent
 ceiling is required because it ensures
 that the MCLG will be low enough to
 provide adequate protection for those
 individuals whose total exposure to a
 contaminant is higher than indicated by
 available data. This approach, in  effect
 results In a slightly lower MCLG and
 increases the margin of safety. EPA
 utilizes the actual percentage when  , •
 adequate exposure "ffata exist and
 indicate ah RSC- between 20 and 80
 percent, but wheri data are not
 adequate, 20 percent Is generally  used

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31784       Faderal R«gbter / Vot. 57. No.  138 / Friday. July 17. 1992 / Rule« and Regulations
as a default value that is protective of
public health. In addition, the Agency
does .not believe that assuming a SO
percent RSC is appropriate for
inorganics or pesticides in the absence
of data, as suggested by a comrhenter. In
fact, there have been numerous
inorganics (such as lead or mercury) and
pesticide* regulated by EPA in public... ••
drinking water supples for which the
available data from all sources indicate
that drinking water likely contributes
less than SO percent to total exposure
and. in some cases, less than 20 percent.
Therefore, there is no basis for
automatically assuming 50 percent from
drinking water when data are not
available.
  There were three chemical-specific
issues regarding setting the RSC. One
RSC issue concerned cyanide. Several
commenters suggested the use of an 80
to 100 percent RSC because they felt
that drinking water represents
essentially all exposure. The Agency
has decided to use a 20 percent RSC for
this contaminant because the available
data on dietary exposure are
inadequate, and the Agency therefore
could  not adequately characterize
overall exposure to cyanide.
  Another commenter claimed that the
Agency misinterpreted a USDA study
(Miller-Ihli and Wolf, 1966] on the
dietary intake, and that EPA should
have used more appropriate data
regarding intake of nickel from food and
air to  calculate the MCLG. The Agency
agrees that the study relied upon in the
proposed rule was inappropriate for
calculating dietary exposure for nickel
because that study analyzed foods that
were freeze-dried, which resulted in
elevated nickel concentrations (higher
than one would determine in fresh
foods). The Agency has recalculated the '
dietary contribution using an FDA diet
study  by Pennington and Jones (1987).
Unlike the Miller-Ihli and Wolf study.
which involved an analysis of freeze-
dried  foods, the Pennington Diet Study
program [Pennington and Jones. 1967] is
appropriate for estimating overall
exposure. The revised calculation
indicates again that drinking water
contributes less than 20 percent of th«
daily  intake. Therefore, the Agency is
using  20 percent as the RSC in the
calculation of the final MCLG for nickel
following present policy of a 20 percent
floor.  Two commenten on the NOA
urged EPA to revise the RSC for nickel
and base a new RSC on analysis of
actual data, as wa» done for antimony..
As discussed above, EPA has done thi* .
and believes the available data, in.   . .'
conjunction with EPA's policy, on RSC
supports the use of the 20 percent'vaJu*.
  The third issue ia related to EPA's
 proposal to use a 20 percent RSC for
 antimony as a default value. The
 Agency agrees with the commenter that
 there is information available on which
 the RSC can appropriately be based.
 The Agency has decided to use an
 occurrence study by Grealhouse and
 Craun (1978^ andhu estimated .typical •'
 levels of 2 jig/1 antimony in drinking
 water. This study was chosen due to its
 large sampling base and
 representativeness of antimony levels
 nationwide. The Agency has also
 recalculated the dietary intake of
 antimony  using a different food study by
 Cunningham and Stroube (1987). The
 dietary contribution of 4.7 fig/day of
 antimony  calculated from this study is
 lower than previously estimation. The
 Cunningham and Stroube  report was
 judged adequate for determining the
 overall exposure estimation. This study,
 conducted by the FDA. uses the
 methodology of their Total Diet Study
 program [Cunningham and Stroube.
 1967). By using an inhalation
 contribution of 0.7 jig/day and the 4.7
 jig/day from the diet along with a mean
 drinking water contribution of 2 ng/1 (or
 4 jig/day), the resulting RSC is 40
 percent (rounded from 42.6 percent). Th«
 NOA requested comment on revision of
 the antimony RSC. and several
 commenters supported the proposed
 revision. The final MCLG for antimony
 reflects this change in the RSC
  The Agency refers readers to the
 Comment  Response Document [USEPA.
 1992a] for  additional detailed
 information on the issues discussed
 above, and for a discussion of other
 exposure/RSC related comments raised-
 during the public comment period.
 3. Inorganic MCLGs
  a. Antimony. EPA proposed an MCLG
 of 0.003 mg/1 for antimony in the July 25,
 1990 proposal [55 FR 3O377J. Antimony
 has been classified in Group D
 (inadequate evidence of cardnogenioty
 In humans) by EPA guideline*. The
proposed MCLG was derived from a
 DWEL of 0.015 mg/L applying a 20
percent contribution from drinking
water. The MCLG was based upon a
LOAEL of 0.43 rag/kg/day for
noncarcinogenic effects in a lifetime
drinking water study in rats [Schroedcr
et aL. 1970). An'uncertainty factor of
1,000 was applied to the LOAEL derived
from a lifetime animal study (which i* in.
accordance with MAS/EPA guidelines).
  No new  toxicological daia that would
change the conclusion* presented in the .
July 25,1990 proposal have became
available since its publication..         \
However, the Agency has revised Us
calculation of the-rtlativesvatw
 contribution for antimony after
 reconsidering the occurrence/exposure
 data, as discussed in the "Relative
 Source Contribution" section above.
 Based on this reassessment of the
 available occurrence/exposure data, the
 final RSC for antimony has been set at
 40 percent. This change in the RSG s ••"•••: •''
 results in a doubling of the final MCLC
 from 0.003 to 0.006 mg/1 for antimony.
   Public Comments: In response to the
 July 25.1990 notice, one individual or
 organization  commented on the MCLG
 proposal for antimony. The commenter
 indicated that an online computer
 search of the Hazardous Substances
 Data Base (rfSDB) showed that
 antimony causes marked weight loss.
 hair loss, dry scaly akin, eosinophilia.
 m'yocardia! failure, vomiting, diarrhea
 and stomatitis in animals orally
 exposed.
   EPA Response: EPA agrees with the
 commenter that antimony causes the
 above mentioned effects when used  in
 high doses in animal tests. These effects
 were discussed in the Health Criteria
 Document for antimony supporting the
 July 1990 proposal [USEPA. 19904
 finalized as USEPA. 1992b]. However.
 the effects reported in the July 1990
 notice are effects associated with the
 critical endpoint of toxicity used to
 establish the  lowesl-observed-adverse-
 effect level (LOAEL) for antimony. The
 effects described by the commenter are
 acute efleets noted at much higher dose
 levels than the dose causing the critical
 effects described in the July 1990 notice.
 Since the critical effects are the basis of
 the DWEL and MCLG calculations for
 antimony, only these effects were
 discussed in the July 1990 proposal.
 Detailed descriptions of antimony
 toxicity at different dose levels and in
 different animal species are documented
 in the Antimony Health Criteria
 Document prepared in support of the
 July 1990 notice [USEPA. 19804
 finalized in USEPA. 1992f]. This
 document is available in the EPA Public
 Docket. Office of Water. Based on the
 available toxicological information and
 on the relative source contribution   -
 reassessment, the Agency is
 promulgating  today an MCLG of 0006
 mg/1 foe antimony.
  b. Beryllium. EPA followed a
Category I approach for beryllium and
proposed an MCLG of zero for beryllium
 in drinking water (55 FR 30378) based on
the evidence of carcinogenic potential
from drinking water. The Agency
requested comment on. setting the MCLC
at zero for beryllium given that th« oral  .
expocurs- biotuayt on not adequate to
conclusively demonstrata a doa«-
        relationship, Beryllium Is

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              Federal Register / Vol 57. No, 139 /Friday.  July 17. 1992 / Rule»  and RegulatJona      31785
 classified in Group B2, probable human
 carcinogen, based on the positive
 carcinogenic findings in several animal
 species exposed to beryllium by
 inhalation and injection. In addition.
 available data indicate tumor induction
 by several beryllium compounds and
 genotoxic.activity in animal .studies. .
 Since the dose-response evidence of
 carcinogenicity specifically by  ingestion
 is limited, the Agency requested public
 comments on setting the MCLG of
 beryllium at zero.
   Public Comments: Eleven commenters
 responded to the beryllium proposal.
 One significant area of comment in
 response to the proposal deals  with the
 carcinogenicity of beryllium via the oral
 route of exposure. The commenters
 disagreed with the Agency on the
 classification of beryllium in Group B2.
 The commenters stated that cancer
 studies performed with beryllium sulfate
 in drinking water [Schroeder et al.. 1970]
 or in feed [Morgareidge. 1977] are
  inadequate because the tumors
  observed in these studies were
  statistically not significant when
  compared with those in controls. One
  commenter suggested that since
  statistical significance was not observed
  in these studies, beryllium should be
  classified as a Group C carcinogen and
  the MCLG should be recalculated using
  the options for Group C compounds. The
  commenter stated that the Agency has
  been inconsistent in its proposed
  regulation for beryllium in drinking
  water because MCLGs have been set at
  non-zero levels for nickel, chromium.
  cadmium, antimony and asbestos, which
  are classified by the Agency in Group A
  or B, via inhalation but in Group C or D
  by the oral route.
     In addition, one commenter sent two
   additional studies of beryllium toxicity
   to EPA during the comment period for
   the November 29.1991 NOA.
     EPA Response: EPA establishei •
   MCLGs for drinking water contaminants
   by placing them in three categories, a»
   discussed above. With regard to the oral
   carcinogenicity of beryllium, EPA hai
   reconsidered the data and agrees with
   the comments regarding the oral
   beryllium studies in that the induction of
   tumors was statistically not significant
   when compared with the controls.
:;  However, the Agency believes that
   these studies show a suggestive
   tumorigenic response which are
r.  consistent with the hazard seen In other
 -  portions of the beryllium data bas«. In
   the July 1990 proposal the Agency
   indicated that these studies were limited
   In their usefulness to evaluate   .
   carcinogenic potential in snlmals
   becaus«-the Schroeder et «L study (1970)
used only one dose, and the
Morgareidge study did not reflect a
traditional dose-response relationship.
In the Morgareidge study, there was an
increase in reticulocyte tumors in rats at
5 and 50 ppm but not at 500 ppm. Taken
together, the available studies show a
limited carcinogenic potential from. .
drinking water ing«*tion, Thii may
relate in part to poor absorption of
beryllium from ingestion. It has been
postulated that ingested beryllium is
precipitated in the gastrointestinal tract
as beryllium phosphate, making it
inaccessible for absorption.
   In general, the mechanisms of
absorption of metallic ions are not well
understood and do not follow a dose-
response relationship. On the other
hand, there .is clear evidence of
carcinogenicity of beryllium via
inhalation or injection in monkeys, rats
and rabbits. Studies in animal species
exposed to beryllium by inhalation or
injection showed tumors at sites
different from the route of exposure
[IRIS, 1989]. Because beryllim produces
tumors in several species (rats.
monkeys, and rabbits) via inhalation  or
injection, the Agency has concluded that
the overall weight of evidence provides
sufficient evidence of carcinogenicity;
therefore beryllium is classified by the
Agency in Group B2 as discussed in the
proposal. However. EPA has also placed
 beryllium in drinking water Category II
 (rather than Category L as proposed)  for
 regulation.
   In response to public comments, EPA
 reevaluated the categorization of
 beryllium by reconsidering its potency,
 exposure, and pharmacokinetics. EPA
 changed its categorization of beryllium
 from Category I to Category II based  on
 several factors. This contaminant is
 poorly absorbed from the
 gastrointestinal tract and the majority
 of the ingested beryllium passes through
 the gut unabsorbed with less than one
.percent being absorbed. Also it is noted
 that while  the carcinogenic potential for
 beryllium is viewed as Group B2 based
 on the overall weight of evidence of the
 inhalation and ingestion data, the dose-
 response analysis for ingestion exposure
  does not provide adequate evidence  of
  carcinogenicity from a drinking water
  source, as is true with many of the other
  B2 contaminant*. Therefore, in- setting
  an MCLG for beryllium k> drinking
  water. EPA believes that a Category U
  approach (which include* a safety factor
  for possible carcinogenic potential) Is
 .appropriate based on the weight of
  evidence- for cardnogenidty via
  ingestion. and also bated on the
  potency, exposure and.
  phannacokinetict of this chemical. EPA
believes that these factors justify
changing the categorization of beryllium
from Category I to Category II.
  For Category II contaminants, EPA
generally sets the MCLG based upon
noncarcinogenic endpoints (using the
RfD approach) with a safety factor
ranging from 1. to 10 applied .ta account,  .
for possible caremogenicity. As stated in
the July 1990 notice (55 FR 30378). EPA
selected a lifetime oral study in rats
(Schroeder et al., 1970) to derive the RfD
and the DWEL for beryllium. An RfD of
0.005 mg/kg/day was derived from this
study using an uncertainty factor of 100
(per NAS/EPA guidelines for use with a
chronic study). This results in a DWEL
of 0.2 mg/1 and an MCLG of 0.004 mg/1.
The derivation of the beryllium MCLG is
given below.
own. •
MCLC
).S »a/lco/dav * 70 fro
 100 x 2 Ut*r*/d*y
                              0.2
                     • °-004
   The DWEL is based on a 70-kg adult
 consuming 2 liters of drinking water per
 day. The MCLG includes an additional
 safety factor of 10 to account for
 possible carcinogenic potential of this
 contaminant via ingestion and assumes
 a drinking water contribution to total
 intake of 20 percent.
   The Agency disagrees with the
 comment alleging inconsistencies with
 other drinking water regulations. To set
 regulations (including those for nickeL
 cadmium, chromium, antimony, and
 asbestos, as well as the MCLG for
 beryllium), each contaminant was
 evaluated independently to assess the
 available health effects data for drinking
 water. EPA considered the overall
 weight of evidence to determine
 carcinogenic potential. The factors
 considered included carcinogenic
 potential by ingestion in  addition to
 other factors, e,g^ cancer potency.  •
 pharmacokinetics, and exposure. The
 above inorganic contaminants are all
 classified in Group A or B according to
 the Agency's classification scheme, but
 were placed into different drinking
 water categories from those that would
 typically apply to the particular
 classifications. The commenter is
 mistaken that EPA classified these
 contaminants as Group C or D
 carcinogens by the oral route of
 exposure. Asbestos (cancer
 classification A) was placed in  drinking
 water Category D due to limited
 evidence of cardnogenidty from
  drinking water cadmium (cancer
 classification Bl) was assigned to-

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31786       Federal Ragkter / y^ 57. NQ. i3& / Friday. July 17. 1992 / Rule* and Regulations
drinking water Category III due to lack
of evidence of carcinogenicity from
drinking water (56 FR 3536). MCLGi for
chromium (as chromium VI) (56 FR 3537)
and nickel (as refinery dust) (55 FR
30382) (proposed), both belonging to
cancer classification A based on the
inhalation route of exposure, were set
following a Category III approach since
data by the oral route show no evidence
of carcinogenicity. In short, a  case-by-
case decision on the categorization of a
contaminant with respect to its
carcinogenicity from drinking water
ir.gestion is made based on the strength
and overall weight of evidence.
  EPA also received two health effects
studies on beryllium submitted during
the December 1991 NOA comment
period. The comment period for
beryllium closed in October 1990. No
additional comments were solicited on
beryllium during the NOA period. In
addition, both studies do not appear to
be peer-reviewed as published. Results
of a preliminary review of these studies
do not indicate they would lead to a
change in the RfD or MCLG for
beryllium.
  One of the studies, by Morgareidge
(1976). reported that in dogs, a maximum
tolerated dose was likely just  above 1
mg/kg/day. a level higher than the 0.54
mg/kg/day NOAEL from the Schroeder
et al. (1970) study above. The other
study, by Ward et al. (undated), is an
epidemiology study of beryllium
workers which presents no dos«
response information.
  Consequently, after review of the
timely public comments and •
reassessment of the information on
cancer and other toxicity concerns, EPA
Is placing beryllium in Category II for
the reasons stated above, and
promulgating an MCLG of 0.004 mg/L
  c. Cyanide. EPA followed a  Category
III approach and proposed an  MCLG of
0.2 mg CN'/l for cyanide in the July 25,
1990 proposal (55 FR 30379). The Agency
has classified cyanide in Group D since
there  are insufficient human and animal
studies for an assessment of iU
carcineogenicity. A DWEL of 0^6 mg
CN~/1 was derived using a NOAEL
value of 10.8 mg CN"/kg/day from a   "
two-year dietary study in which rat*
were administered diets containing
hydrogen cyanide (Howard and HanzaL
1955). In calculating the DWEL. in
uncertainty factor of 100 was applied (in
accordance with NAS/EPA guidelines
for a lifetime animal study). An
additional modifying factor of 5 was
used to account for the possibility that
cyanide would be absorbed more
readily from drinking water than from
food. The 0-2 mg CN~/1 propoeed MCLG
is a rounded value (from OJ5 mg CN~/1)
 derived from the DWEL and assuming a
 relative source contribution of 20% due
 to exposure from drinking water.
   Public Comments: A total of eight
 individuals or organizations provided
 comments in response to the MCLG
 proposal regarding cyanide. Six
 commenters raised, the issue of cyanide-
: speciation. These commenters stated
 that while the proposed MCLG is based
 on "free cyanides." the proposed
 analytical methods imply that "tola!
 cyanides" will be regulated. While "free
 cyanides" are readily bioavailable and
 extremely toxic, "total cyanides"
 contain all cyanides, including those
 low-toxicity. inert species that are
 undissociable (to CN~) and not
 absorbable (see the Analytical Methods
 Section for additional information).
   Two commenters questioned the
 appropriateness of the NOAEL (10.8 mg
 CN~/kg/day) that was selected for the
 MCLG calculation. One commenter
 suggested that the study by Howard and
 Hanzai (1955) is not preferable since no
 effects were observed in rats at the
 highest test dose level of 10.8 mg CN"/
 kg/day, and studies should be designed
 to show an effect at the highest dose
 tested. Thus, this commenter claims that
 no NOAEL was identified. The other
 commenter stated that the rat LD*.
 (reported range of 1-4 mg CN"/kg) is
 lower than the NOAEL(10.8 mg CN'/kg/
 day) used in the MCLG calculation. The
 commenter questioned whether the
 proposed MCLG will pose an acute
 hazard if a large amount of water was
 ingested at one time.  Also, two
commenters questioned the necessity of
 using a modifying factor of 5 in the
. derivation  of the MCLG since the actual
bioavailability of cyanide was not
measured upon oral exposure through
diet or drinking water.
   EPA Response: In response to the
comments concerning cyanide
speciation. EPA is promulgating today
an MCLG and MCL for cyanide that
apply only to free cyanide. The Agency
agrees with the commenters that only
free cyanides should be regulated
because these are the species of heahh
concern due to their bioavailability and
toxicity. The analytical methods issue is
fully addressed in the Analytical
Methods section of this rule. In
summary. EPA is specifying the use of
the "cyanide amendable to cbJorination"
test for determining the "free cyanide"
concentrations, while the "total
cyanide" analytical technique is being
allowed to  screen samples. If the "toUl
cyanide" results are greater than the
MCL. then the analysis for free cyanide
would be required to determine whether
there is an exceedance of the MCL.
    EPA considers the NOAEL selected to
  be appropriate and to be protective
  against adverse health effects over a
  lifetime of exposure. The selection of a
  NOAEL of 10.8 mg CN'/kg/day is based
  on sensitive endpoint of toxicity and is
  consistent with a study that found a
.  NOAEL of »mg/kgCN-per day for '
  weight loss, thyroid effects, and myelin
  degeneration in rats reported in a 11.5-
  month dietary study using KCN
  (Philbrick et al.. 1979]. The commenter
  noted that the reported low LDM in rats.
  was lower than the selected NOAEL
  However, the rat lethal dose of cyanide
  was an acute effect obtained by
  administering cyanide in bolus form by
  gavage. The NOAEL chosen is from a
  two-year chronic dietary study. Studies
  have shown that rats (and humans) can
  tolerate higher doses of cyanide (80 mg
  CN~/kg/day) when mixed in the diet
  [Kreutler et al.. 1978) than when
  adminidtered in bolus form by gavage in
  aqueous solution (LD,.=4 mg CN"/kg/
  day) (Ferguson. 1962). Rats also
  tolerated a higher oral dose of cyanide
  (12 mg CN"/kg/day for 21 days that was
  administered in drinking water Palmer
  and Olson. 1979). The intermittent
  ingesrion of low doses over a day would
  allow for sufficient detoxification.
   Using the NOAEL chosen, an
  uncertainty factor of 500 was used in the
  calculation of the DWEL. This includes
  an uncertainty factor of 100 (for use of a
  NOAEL derived from a Chronic Study)
  and a 5-fold modifying factor to account
  for the fact that the NOAEL is from a
  dietary study.
   The fatal oral dose of cyanide in
  humans reported by several
  investigators ranged from 0.5 to 3.5 mg/
  kg CN-. The LD*° values and LOAELs
  for various acute (1-14 days) and
  subacute (90 days] effects in tested
- animals were reported in the same range
  as the human lethal levels or higher
  (USEPA. 1988b. finalized as USEPA.
  1992h]. Assuming an average human
  body weight of 70 kg, the approximate
  fatal dose of CN" would be no less than
 35 mg (04 mg/kgx70 kg). At the final
 MCL of 0.2 mg/1 promulgated today, a
 person would need to ingest 175 liters of
 water (35 mg+O2 mg/1) in one short
 time interval to obtain an acutely  toxic
 dose, an unrealistic volume to consume.
 Therefore, EPA believes the derived
 MCLG in protective of both acute and
 chronic toxic effects of cyanide in
 drinking water.
   After review of the comments. t*x
 Agency believe* that the proposed
 MCLG fir supported by the available
 health dttc and is promulg«tinf today
 as MCLG of OL2 Bg/I for free cyanxi*.

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              Federal Register  /  Vol. 57, No. 138  / Friday, July 17. 1992 /Rules and Regulations
                                                                     31787
   d. Nickel. On July 2S. 1990. EPA
 proposed an MCLG of 0.1 mg/1 for nickel
 (55 FR 30381]. The MCLG was based on
 the Ambrose et al. 1976 study where rats
 were fed nickel sulfate hexahydrate in
 their diet for 2 years. Effects noted in the
 animals included decreased body
 weight in male and female rats, as well
 as increased: relative heart weight and' •
 decreased relative liver weight in female
 rats. Other studies reported decreased
 body weight gains and organ weight
 effects. A NOAEL of 5 mg Ni/kg body
 weight was identified in the Ambrose
 study. This NOAEL is supported by a
 short term gavage study [American
 Biogenics. 1986].
'   Nickel refinery dust and nickel
 subsulfide are classified in Group A:
 Human carcinogen based on human
 epidemiologic data from occupational
 exposure via inhalation. Nickel was not
 demonstrated to be carcinogenic by the
 oral route of exposure in several animal
 studies. The soluble nickel salts that
 may be found in drinking water have not
 been classified as to their carcinogenic
 potential Nickel is considered to be an
 essential trace element for some animal
 species, although it has not been shown
 to be essential for humans. It is found as
 a normal constituent in the human diet.
 with average intakes of 100 to 500 jiig/
 day. EPA proposed an MCLG for nickel
 following a Category III approach
 considering the  lack of evidence of
 carcinogenicity  by ingestion.
   Public Comments: Comments are
 requested on the MCLG for nickel and
 the carcinogenicity potential for nickel
 in drinking water. Fourteen commenU
 were received Comments were received
 on the derivation of the MCLG which
 discussed the choice of study and toxic
 endpoint as the basis for the MCLG, use
 of uncertainty factors, assumed volume
 of water consumed daily, exposure from
 ' water and carcinogenic potential for
 ingested nickel.
   One commenter stated that the dose
 of 5 rag/kg/day should be considered a
 no-observed-effect level [NOEL) instead
 of a no-observed-adverse-effect level
 (NOAEL) since no effects, adverse or
 otherwise, were noted. They also noted
 that the next highest dose (50 mg/kg/d)
 could arguably be called a NOAEL
 instead of a LOAEL since the effect of
 decreased body weight could be the
 result of decreased food consumption
 possibly due to taste aversion.
    A few comments were received on the
  use of a 3-fold modifying factor in the
  RfD calculation. These commenter* *aid
  that EPA should not use the additional
  factor of 3 to account for deficiencies in
  the data base for reproductive effect*
  because the factor of 100 is already
  conservative and the available
reproductive data demonstrated a
NOAEL comparable to the Ambrose
study. It was suggested that EPA defer
establishing an MCLG for nickel until all
reviews of reproductive studies are
completed,  which would eliminate the
need for a modifying factor of 3.
  Comments were received which
discussed: consideration of reproductive :
or dermatitis studies related to nickel in
drinking water as the basis for the
MCLG. These studies suggest that
reproductive or derma tological
endpoinrs may be more sensitive than
the Ambrose feeding study! The
commenters agreed with EPA's position
that the reproductive and  dermatitis
studies were not appropriate, to serve as
the sole basis for the RfD  due to
problems with the study design. The
commenters stated further that  EPA has
been more than conservative in using
the NOAEL from the Ambrose feeding
study, that  there may be a potential for
differential absorption from food versus
water, and  that the reproductive and
dermatological studies in  fact support
the current RfD estimated from the
Ambrose feeding study. Another
commenter indicated that ingested
nickel exerts its toxicity through
irritation to the gastrointestinal tract
and not inherent toxicity due to low
intestinal absorption.
  One commenter indicated that the
DWEL should not be adjusted by a
relative source contribution from water
in that the DWEL is  already
conservative and that actual exposure
data should be used. Because actual
data show  less exposure than EPA's
default relative source contribution, the
MCLG should be 5 to 8 times higher than
it is. They further stated that the volume
of 2 liters of water per day was an
overestimate and that a vahie of 1.4
liters/day taken from the
recommendations of the EPA Exposure
Assessment Group should be used.
  Several commenters supported EPA's
position not to treat nickel as a
carcinogen in drinking water.
  EPA Response: EPA maintains that
the 5 mg/kg/day dose level in the
Ambrose feeding study is appropriately
considered a  NOAEL and that the higher
dose of 50 mg/kg/day is a LOAEL In
females given the done of 50 mg/kg/day,
decreased  body  weight increased
relative heart weight and decreased
relative liver weight were all
statistically significant Therefore, based
on scientific judgment and statistical
significance (concurred in by SAB), SO
mg/kg/day is considered the LOAEL.
All of the above effects were also
observed at the lower dose level of 5
mg/kg/day but were not statistically
significant. Thus, the 5 mg/kg/day level
is a NOAEL
  EPA agrees that nickel may be
irritating to the gastrointestinal tract;
however, there is evidence to indicate
systemic effects following chronic low
dose exposure. Therefore. EPA
disagrees that nickel lacks inherent  .
toxicity.- . • •  •   •   •   •     .,-
  EPA disagrees that the modifying
factor of 3 is not justified. While the
existing reproductive studies are not
adequate for use as the sole basis for the
RfD and DWEL they do indicate a
potentialreproductive  hazard that may
result from oral exposure to nickel. A
modifying factor of 3 accounts for the
uncertainties for the equivocal nature of
the dose-response data from the existing
reproductive studies.
  EPA agrees with the comments that
the dermatological studies should not be
the basis for the NOAEL in that oral
nickel challenge studies ideally should
be conducted in a double blind manner.
The commentators and EPA agree.
however, that the dermatological and
reproductive studies support the RfD
and DWEL in a weight-of-e\ idence
approach.
  The Agency disagrees with the
commenter who stated that the DWEL
should not be adjusted by a relative
source contribution but that actual
exposure data showing lower exposure
should be  used. EPA agrees that
available data indicate that drinking
water contributes less  than 20 percent of
.the daily intake, but EPA uses 20
percent as a minimum  percentage in
these cases (see "Relative Source
Contribution" section above).  •
  In response to the commenter's
suggestion to use 1.4 liters/day as the
assumed water consumption instead of 2
liters/day, EPA continues to believe that
the use of 2 liters/day  is appropriate in
setting the MCLGs. as  recommended by
NAS (1977). The Agency has
consistently used 2 liters/day as an
assumed consumption in past drinking
water regulations. The NAS estimate
was based on a survey of nine different
literature sources which gave an overall
average per capita water (liquid)
consumption per day of 1.63 liters. It
also concluded that  the volume of 2
liters/day represented the intake of the
majority of water consumers. In order to
be conservative and allow for an
adequate margin of safety, EPA uses the
2 I/day value. Further, the use of 1.41/
day  in the EPA Exposure Assessment
Group handbook is not inconsistent with
EPA's approach of using 2 I/day in this
and  other, drinking water rules. The 1.41
value is an overall average of a number
of studies, tome of which did not

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317bb       Federal Regiiter / Vol. 57. No.  130 / Friday. July 17. 1992 / Rules  and  Regulations
necessarily consider indirect water
consumption (such as use in cooking).
Therefore, to best account for all
exposures related to the occurrence of
contaminants in drinking water. EPA
believes use of 2 liters daily water
intake is conservative and appropriate.
The Exposure Assessment.Group.-. •••
Handbook also notes that 2 liters intake
is a reasonable worst case estimate.
  With respect to a factor  to account for
potential differences in absorption of
nickel from food and water, EPA
acknowledges that data are available
which suggest a potential for differential
absorption. However, these differences
are not clearly reflected in the dose-
response relationships from the toxicity
studies. In particular, the gavage study
[American Biogenics. 1986] exposed rats
to nickel chloride dissolved in water.
This study identified the same NOAEL
(5 mg Ni/kg/day) as the dietary study
[Ambrose et al.. 1976] which serves as
the basis for the RfD. Thus, application
of a modifying factor to account for
differential absorption is not considered
to be justified by the existing data.
  After review of the public comments,
EPA is promulgating the MCLG for
nickel at 0.1 mg/1. as proposed.
  e. Sulfate. In the July 25,1990 notice.
EPA proposed two alternative MCLGs of
400 and 500 mg/1 for sulfate. People who
continually ingest high levels of sulfate
in their drinking water generally
acclimate to the sulfate and are resistant
to its laxative properties. Even though
promulgation of the MCLG is being
deferred, for reasons discussed in
Section IILB.5  of this notice, a
discussion of comments received and
EPA's response follows below.
  Public Comments: There were 15
separate comments concerning sulfate.
Several commenters believed that EPA
should npt regulate sulfate due to a lack
of adequate health data, lack of chronic
effects and because of acclimatization
(refractoriness to the laxative effects) to
sulfate. Eleven commenters stated that
the sulfate regulation should be higher
than 500 mg/1  (between 600 and 1.000
mg/l). Six commenters stated that 500
mg/1 was protective, while three others
believed that the 400 mg/1 option would
be better. One commenter stated that
the usual approach for deriving the
MCLG—an RID and DWEL
calculation—should be used for sulfate.
Another commenter cited a 1989 letter
dated July 17,1989 from the Metals
Subcommittee of the Science Advisory
Board's Environmental Health
Committee to  the Administrator stating
that the Subcommittee could not support
the setting of an acute DWEL. Other
commenters urged no regulation of
sulfate, stating thct: a secondary MCL is
sufficient for sulfate, infants as well as
adults acclimate to sulfate. sulfate is
present in food, and the WHO
guidelines are based on taste and not on
health effects.
  EPA Response: As noted above. EPA
is deferring action on the sulfate MCLG
and MGL. Some-commenters'noted that''
no chronic health effects have been
associated with long-term exposure to
high levels of sulfate. However, sulfate
can have acute adverse effects on non-
acclimated persons. The critical health
effect that results from exposure to
sulfate in drinking water is diarrhea.
Diarrhea has been reported at a level as
low as 630 mg/1. The population most
likely to experience this effect consists
of travelers and infants not accustomed
to high sulfate levels. This laxative
effect eases and disappears (i.e., the
person acclimatizes to the effects of
sulfate) with continued exposure  to high
levels of sulfate in water. Little or no
information is available on how quickly
people, particularly infants, acclimate to
the effects of sulfate.
  Due to the acute nature of the critical
effect, an RfD and chronic DWEL were
not determined. Available data indicate
that infants may be the most sensitive
subpopulation since they may be  at risk
of becoming dehydrated (which may be
serious if not properly treated) as a
result of prolonged diarrhea [Chien et
al..  1968J.
  The Metals Subcommittee of the
Science Advisory Board's
Environmental Health Committee
recommended additional study before
regulation but  noted that, if regulated
an MCLG of 400 mg/1 [Loehr, 19891 was
more appropriate  than the 200 mg/1
recommended at the  time by the
Agency. The basis for the SAB
recommendation was that (1) the mode
of action of sulfate is fairly well known.
and (2) some human data are available
which indicate that ill effects occur only
at concentrations  above 600 mg/1.
  At the time EPA proposes a decision
on sulfate. it will present a discussion of
its science assessment, including any
new information which may'become
available.
  f. Thallium. EPA proposed an MCLG
of 0.0005 mg/1 for thallium in the July
1990 proposal [55 FR  30383J. The MCLG
was derived using a NOAEL of 0.2 mg
thallium/kg/day from a 13-week dietary
study in rats [Stoltz ei-al. 1986]. Based
on this NOAEL. a DWEL of 0.0023 mg/1
was calculated. An uncertainty factor of
1,000 was applied (in accordance with
NAS/EPA guidelines for a subchronic
study). An additional uncertainty factor
of 3 was used to account for the lack of
adequate reproductive data. EPA  ha*
classified thallium in Group D since
 there is inadequate evidence of
 carcinogenicity. No new data that would
 change the conclusions presented in the
 July 1990 notice have become available
 since its publication.
  Public Comments: In response to the
.July. .1990 notice..three individuals on^'"-'-'
 organizations commented on the
 proposed MCLG for thallium. The most
 significant area of comment was the
 claim that the uncertainty factor of 3.000
 used to establish the MCLG for-thallium
 is overly conservative given the nature
 of the health effects data involved, and
 that an uncertainty factor of 1,000
 should be sufficient. The commenter did
 not believe that an extra uncertainty
 factor of 3 was warranted for protection
 from potential reproductive effects.
  EPA Response: EPA disagrees that the
 uncertainty factor of 3.000 is overly
 conservative. The only data available
 are from subchronic exposure of
 rodents. A factor of 1,000 is generally
 used with a NOAEL derived from an
 animal study of less-than-lifetime
 duration (the 1986 Stoltz et al. study was
 13 weeks in length). The additional
 uncertainty factor of 3 was applied in
 the risk assessment to compensate for
 the lack of adequate reproductive data.
 In light of the results from Formigli et al.
 (1986) in which thallium induced
 testicular toxicity in rats at 0.74 mg
 thallium/kg/day administered in the
 drinking water for 8 weeks, EPA
 believes it is appropriate to use an
 additional uncertainty factor of 3 since
 the possibility that this effect may occur
 at doses at or below the selected
 NOAEL of 0.2 mg thallium/kg/day
 cannot be ruled out. Detailed
 descriptions of thallium toxicity at
 different dose levels and in different
 animal species are documented in the
 thallium Health Criteria Document
 prepared in support of this regulation
 [USEPA. 1990g, finalized in USEPA.
1992cJ. Accordingly, based on the
available information, the Agency is
promulgating today an MCLG of 0.0005
mg/1 for thallium.

4. Organic MCLGs
  a. BenzofaJPyrene and other PAHs. In
the July 1990 notice, EPA discussed the
available information on the health
effects, occurrence and human exposure
for 15 Polynuclear Aromatic
Hydrocarbons (PAHs) {55 FR 30396]. Of
the 15 PAHi. seven were presented in
greater detail because of their
carcinogenic potential (all classified as
Group B2, probable human carcinogen),
and were proposed for regulatory
consideration. These included:
Benz[a]anthracene (BaA).
benzo[ajpyrene (BaP).

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             Federal RagUtet  / VoL 57.  No. 138  /  Friday. July 17. 1992 / Rules  and Regulation*	31783
 benzo[b]fluoranthene (BbF).
 benzo[kjfluoranthene (BkF). chrysene
 (CHY). dibenz[a.h]anthracene (DBA).
 and indeno(1.2.3-c.d]pvrene (IPy). In tne
 proposal. EPA presented alternative
 approaches for controlling exposures: (1)
 Setting MCLG of zero for BaP alone.
 based on its carcinogenic potential and
 (2) setting an MCLG of zero for each of
 the seven carcinogenic PAHs. Only for
. BaP are sufficient data available to
 make a quantitative estimate of cancer
 potency.  In a study wherein mice were
 fed BaP in the diet treatment-related
 gastric tumors developed, another
 dietary study in rats produced similar
 results. Data from these studies form the
 basis for the quantitative estimate of
 cancer potency [Neal and Rigdon. 1967).
 BaP is mutagenic in vitro mutagenicity
 tests, and has been found to produce
 reproductive effects in animals. Skin
 painting studies in animals indicate that
 the effectiveness of inducing skin cancer
 of the other six PAHs are equal to or
 less than that of BaP (see studies cited
 in Criteria Document [USEPA. 1988C.
 finalized as USEPA, 1991f])- The Federal
 Register notice solicited public
 comments on: The Agency's two
 alternative options: regulation of other
 PAHs: and alternative approaches for
 evaluating the carcinogenic potency for
 BaP. The major comments are discussed
 below.
    Public Comments: There were 17
 comments  submitted to the Agency
 concerning health-based issues on the .
 proposal to regulate PAHs. Eight of the
 comments  stated that the Agency should
 limit the regulation to BaP  only. Three of
 the comments suggested regulating all
 seven of the Group B2 PAHs using a
 comparative potency approach, with
 comparison to BaP. One comment
 indicated that individual MCLGs should
 be established after the comparative
 potencies are validated. The validation
  method was not specified. There were
  several comments which suggested that
  the Agency should not  regulate PAHs.'
  The basis  claimed for this
  recommendation was either that data to
  determine health effects were not
  sufficient, or that exposure to PAHs in
  drinking water was negligible when
  compared to other sources. There also
  were comments that did not agree with
  the Agency's approach of selecting
  Category I and setting  a zero MCLG for
  contaminants'that show evidence of
  carcinogenicity via ingestion. Some
  commenters described the Agency's
  approach  as being overly conwrvative:
  overestimating riskiand not accounting
  for a threshold of carcinogenicity.
  Specific suggestions were: (1) To set
  MCLGs/MCLs at a de  minimus level
(e.g.. 10~4) or at background levels: (2)
use a biologically based (e.g., two-stage
or fitted multistage} model to estimate
cancer risk, instead of the linearized
multistage model: and (3) use body
weight scaling, instead of surface area.
to extrapolate animal data to human
exposure* for estimating cancer risk:v    .-
  EPA Response: EPA has decided to
establish an MCLG (and MCL) for BaP
only. There are-extensive and sufficient
data to support regulating BaP. It has
been shown to be carcinogenic in
animals by many routes, including by
ingestion. and has been classified by the
Agency as a Group EZ probable human
carcinogen. Even though less than one
percent of PAH exposure may come
from drinking water, PAHs have been
found in some drinking water sources.
  The Group B2 classifications and
frequency of association of the other six
PAHs with BaP as a mixture in drinking
water suggest that it may be appropriate
to regulate these others also. The
Agency is considering regulating BaA.
BbF, BkF, CHY. DBA, and IPy using a
comparative cancer potency approach;
the individual potencies would be
compared to that of BaP. Such regulation
may be proposed at a future date when
EPA has established a policy for how
such a comparative approach would be
conducted, or when other appropriate
data become available for any or all of
the six PAHs.
   The EPA approach to estimating
cancer risk for drinking water
contaminants (i.e., weight-of-evidence
determination and non-threshold low-
dose extrapolation) is considered to be
the most prudent approach that is
protective of human health. The Agency
considers and evaluates alternative
methods for assessing human health
risks to chemicals. Risk estimates using
a variety of models (including two-stage,
linearized multistage, and Weibull
methods) have been applied to the BaP
data. In the interest of using more of the
available data, the slope factor of 5.76
(mg/kg/dayr1 was derived. This slope
factor is the geometric mean of all the
models used. While data on the
potential mechanism of action of an
agent are considered in the weight-of-
 evidence judgment, evidence of a
 nongenotoxic mechanism, while
 pertinent, would, not always exclude
 classification of'a chemical as a
 probable human carcinogen. The
 appropriate scaling factors for
 interspecies extrapolation are being
 reviewed currently by the EPA and
 other Federal agencies. However, the
 Agency will continue to use surface area
 scaling to estimate cancer riiks until
 there is sufficient evidence to support a
change and until another approach is
fully approved and adopted.
  Based on the above discussion, which
considers the toxicity. carcinogenicity.
occurrence, and exposure of BaP. BaA.
BbF. BkF. CHY. DBA. and IPy. EPA has
concluded that only BaP should be
regulated at this time: In most cases, the' "•
Agency places Group B2 contaminants
into EPA Category I when there is strong
evidence of carcinogenicity via
ingestion. EPA's policy is to set MCLGs
for Category I chemicals at zero. Based
on the weight-of-evidence for
carcinogenicity, the Agency places BaP
in Category I and is promulgating today
an MCLG of zero for this contaminant.
  b. Dalapon. In the July, 1990 proposal
[55 FR 30385], EPA proposed an MCLG
of 0.2 mg/1 for dalapon based on a two-
year feeding study in rats [Paynter et aj..
I960]. A NOAEL of 8 mg/kg/day was
identified from this study. From the
NOAEL a DWEL of 0.93 mg/1 was
derived. An uncertainty factor of 100
was  applied to the NOAEL following
NAS/EPA guidelines for a lifetime  .
study. An additional uncertainty factor
of 3 was used to account for possible
inadequacy of the available animal
data.
  Public Comments: Three comments
were received on the health effects of
dalapon that were editorial in nature.
There was no major disagreement
between any of the commenters and
EPA. One commenteT misread the   .
uncertainty factor of 300 as 800. The
second commenter agreed on the value
but suggested the  use of the term
"uncertainty factor" be used
consistently to account for inadequacy
of toxicological data instead of the term
"modifying factor." The third commenter
needed clarification on the title of a
reference.
   EPA Response:  EPA agrees with the
commenter that suggested that "3" is an
uncertainty factor (which is synonymous
with "modifying factor") to account  for
the inadequacy of the data base.
Because none of the comments affect the
proposed MCLG, based on the available
information, the Agency is promulgating
today an MCLG of 0.2 mg/1 for dalapon.
   c.  Dichloromethane (Methylene
chloride). In the July 1990 notice [55  FR
30386], EPA proposed an MCLG of zero
for dichloromethane. This MCLG was
based on the classification of this
contaminant as a  Group B2 carcinogen.
EPA requested comments on whether
the available carcinogenicity data by
ingestion are adequate to classify
dichloromethane in Group B2. and on
the proposed MCLG.
   Public Comments: Eleven comments
were received in responw to the

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3^790       Federal  Register / Vol. 57. No. 138 / Friday. July 17.  1992 / Rules and Regulations
proposed regulation of dichloromethane.
The majority of the commentert
questioned the classification of
dichloromethane in Group B2—probable
human carcinogen. One commenter
suggested that EPA should not regulate
dichloromethane as a known human
carcinogen since no human'data are
available. Several commenters argued
for the classification in Group C while
others favored a classification in Group
D. These commenters stated that there
are limited or inadequate data to
classify dichloromethane as a Group B2
carcinogen. One commenter agreed with
the EPA cancer classification in Group
B2 for dichloromethane.
  EPA Response: EPA disagrees with
the comment that the Agency is
regulating dichloromethane (DCM) as a
known human carcinogen (i.e.. Group A
carcinogen). The Agency has classified
dichloromethane in the cancer
classification of Group B2. probable
human carcinogen. EPA has placed
dichloromethane in Category I to set the
MCLG* because there is sufficient
evidence of carcinogenicity in animals
from drinking water exposure.
  EPA disagrees with the commenters
supporting classification of
dichloromethane in Group C [possible
human carcinogen) or Group D
(inadequate evidence for classification).
EPA believes that there is sufficient
evidence that dichloromethane induces
tumors in animals. In drinking water
studies [Serota et al., 198&a.b],  a
statistically significant increase in the
incidence of combined hepatocellular
carcinoma and neoplastic nodules when
compared with matched controls was
observed (female rats). Male mice had
an increased incidence of combined
neoplastic modules and hepatocellular
carcinoma. In an inhalation experiment
[IRIS. 1991a], statistically increased
incidences of mammary adenomas and
flbroadenomas were observed in male
and female rats. Mice also showed
increased incidence of hepatocellular
adenomas and carcinomas. These data
support the classification-of
dichloromethane in Group B2 and
provide specific evidence for ingestion
exposure hazard.
  Consequently, based on the
information available to the Agency and
the public comments received. EPA has
concluded that dichloromethane should
be placed in Category L and that an.
MCLG'bf zero. a« proposed. i»  '
appropriate.
  d. Di(Z-ethylhexyl) adipate. In the July
1990 proposal [55 FR 30384], EPA
proposed an MCLG of 0.5 mg/1 for di(2-
ethylhexyl) adipate (DEHA). This MCLG
was derived from an NTP 2-year dietary
study in rats and mice which resulted in
a NOAEL of 700 mg/kg/day (NTP.
1982a]. An uncertainty factor of 100, and
an extra uncertainty factor of 10 for lack
of adequate reproductive effects data,
were applied to the NOAEL to derive a
DWEL of 25 mg/l. The MCLG of 0.5 mg/1
was calculated for DEHA from this
DWEL by applying an additional safety
factor of 10 in accordance with OW
policy for Group C carcinogens, and by
assuming a 20 percent contribution from
drinking water to total exposure.
  Based on new health information (see
discussion below), EPA has recalculated
the proposed MCLG for DEHA. A full
discussion on the basis for the revised
MCLG for DEHA was given in the
November 19.1991 Notice of
Availability (56 FR 60953J.
  Public Comments: Two commenters
responded to the July 1990 proposal.
Both commenters questioned the use of
an extra uncertainty factor of 10 in the
calculation of the DWEL to account for
the lack of data on reproductive effects.
One commenter claimed that the extra
uncertainty factor of 10 should not be
used because there are the 1988 ICI
teratology and reproductive studies
available for this chemical [ICI. 1988a.bJ.
  One commenter on the NOA asserted
that the 3-fold additional uncertainty
factor should not be justified in part by
the observation of dilated ureters in
fetuses in the ICI study [Id, 1988aJ.
because the noted effect wa* not
statistically significant. If these data
were used to justify use of an
uncertainty factor, a value less than 3
 should be used, according to the
 commenter.
   EPA Response: As discussed in the
 November 29.1991 Notice of
 Availability. EPA has reviewed the 1988
 ICI teratology and reproductive studies
 and considers.them.adequate.,and'.,
 suiufalt to serve as the basis for the
 MCLG for DEHA.
   In the teratogenicity study, Wistar-
 derived pregnant rats (24/group) were
 fed diets  containing DEHA to a 300,
 1,800 or 12.000 ppm corresponding to
 dosages of 0. 28,170 or 1,080 mg/kg/day
 on gestational days 1-22 [ICL 1988aJ. At
 the high dose, slight reductions in
 maternal body weight gain and food
 consumption were observed, and
 reduced ossification and kinked or
 dilated ureters were found in the
 fetuses. Slightly dilated ureters were
 also seen in a few fetuses at 170 mg/kg/
 day but the incidence did not reach
 statistical significance. The LOAEL and
 the NOAEL for this study were 1.080
 mg/kg/day, and 170 mg/kg/day.
 respectively.
  In a companion one-generation
 reproductive study [ICI, 1988bj, group's
 of Wistar-derived rats (15 males/dose;
 30 females/dose) were administered
 DEHA in their diets at the same levels
 (0. 28,170 or 1,080 mg/kg/day). After 10
 weeks on the diet the animals were
 mated to produce one generation of
 offspring  that was reared to day 38 post
 partum. Test diets were fed
 continuously throughout the study
 (approximately 18-19 weeks of
 exposure). No effects were seen on male
 or female fertility. However, at the
 highest dosage level, there was a
 reduction in the body weight gain of the
 dams during gestation; an increase in
 liver weight in both male and female
parents; and reductions in offspring
weight gain, total litter weight and  litter
 size. The NOAEL for this study was also
170 mg/hg/day.
  Based on the NOAEL of 170 mg/kg/
day, an RfD of 0.6 mg/kg/day and a
DWEL of 20 mg/1 is calculated for a 70-
kg adult consuming 2 liters of water per
day using an overall uncertainty factor
of 300.
                     DWEL  -
                                  3  X  100


                                0.6 rag/kcr/dav  x  70 kg
             -  0.56
                (rounded  to  0.6  mg/Jcg/day)
                                           2  I/day
                            «  21 mg/1

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             Federal Ragirtar / VoL 57. No. 138  /  Friday, July 17.  1992 / Rules and  Regulations
                                                                                                   31791
where:
  70 kg is the aisumed body weight of an
    adult person
  TOO is the uncertainty factor following EPA
    guidelines for a NOAEL obtained in a
    study using laboratory animals
  3 is the additional uncertainty factor used
    because of data base deficiencies
    including.lack of a multi-generation i:" • .-
    reproductive study.
  In the November 29.1991 Federal
Register Notice. EPA presented this
recalculated DWEL and the proposed
MCLG for DEHA  based on the DWEL of
21 mg/1. an additional safety factor of
10 in accordance  with EPA policy for
Category II contaminants and an
assumed drinking water contribution of
20% to total exposure.
MCLS
21 BQ/1
  10
X 0.2 - 0.4 stg/1
   EPA agrees that because the effect on fetal
 ureters in the ICI study [1CI. 1988a] was not
 statistically significant, this effect should not
 be used in justifying the additional 3-fold
 uncertainty factor. However. EPA believes
 the data gap cited (lack of a multi-generation
 study) does warrant use of the additional 3-
 fold uncertainty factor.
   Therefore, based on  the new toxicity
 data. EPA is placing DEHA in Category
 II (Group C) and promulgating an MCLG
 of 0.4 mg/1 in today'i notice. This MCLG
 of 0.4 mg/1 corresponds to a theoretical
 cancer risk level of 1.3  x 10*.
   e. Di(2-ethylhexyl)phthalate. In the
 July 1990 notice [55 FR 30398]. EPA
 discussed the available information on
 the health effects, occurrence and
 human exposure for four phthalates:
 di(2-ethylhexyl)phthalate (DEHP). butyl
 benzyl phthalate (BBP), dibutyl
 phthalate (DBP) and diethylphthalate
 (DEP). In that notice. EPA proposed to
 set an MCLG of zero for DEHP based on
 its classification as a Group B2
 carcinogen. The Agency based on the
 cancer classification on a weight-of-
 evidence approach for sufficient
 evidence of carcinogenicity in animals.
 DEHP caused hepatocellular adenomas
 and carcinomas in both sexes of rats
 and mice fed DEHP in the diet The
 Agency discussed three regulatory
 options which included: regulating only.
 DEHP based on its carcinogenicity;
./regulating DEHP and BBP. the latter
 based on a systemic toxic endpoint; and
 regulating all four phthalates separately,
* based on systemic endpoints for all
 . except DEHP. Based on toxicity,
 occurrence, and exposure
 consideration*, the Agency proposed
 that only DEHP should be regulated. The
 available occurrence data indicate that
 DEHP has been found most often in
drinking water while the three other
phthalates have rarely been found, and
the reported levels of the others are
below levels of health concern. Also.
drinking water is a minor route of
exposure to phthalates in general.
further adding to the likelihood of low
risk. The Federal Register notice,...
solicited public comments on the
Agency's proposal to regulate only
DEHP and also on the other options. The
major comments' are discussed below.
  Public Comments: There were five
comments submitted to the Agency
concerning health-based issues on the
proposal to regulate DEHP and other
options. There were no comments
addressing the third option, i.e..
regulating all four phthalates separately.
One commenter agreed with the EPA
proposal to regulate DEHP only.
Another commenter suggested that the
MCLG for DEHP should be based on the
DWEL rather than on its carcinogenicity
because the evidence for carcinogenicity
is insufficient. In support of this
position, the commenter stated that (1)
DEHP's classification as a Group B2
carcinogen has been considered but
never finalized by the Agency; (2) based
on scientific uncertainty (e.g.. with
mechanism of action, structure activity
relationships, potency, genotoxicity,
species differences, etc.) a B2
classification is inappropriate: and. (3)
the European community has concluded '
that DEHP is not a human carcinogen.
   The other three comments were about
BBP. The comments on BBP were: (1)
That the MCL should be set only for
DEHP until sufficient data  exists to set
MCLs for BBP and other phthalates; (2)
that the classification of BBP in Group C
(possible human carcinogen) is not
sufficient to warrant its regulation: and
(3) that the NOAEL to calculate the
DWEL and MCL is quantitatively
incorrect and should be increased by a
factor of 3 because no dose/response
relationship was found.
   EPA Response: EPA does not agree
with the position that there is a lack of
evidence for classifying DEHP as a
probable human carcinogen. According
to the Agency's Guidelines for
Carcinogen Risk Assessment [USEPA,
1986], the overall weight-of-evidence
provides sufficient evidence in animals
to classify DEHP as & Group B2
(probable human) carcinogen. EPA's
CRAVE verified the Group B2
classification for DEHP on November 7.
1987. The classification wa* based upon
 the  NTP study [NTP. 1982b). which
 resulted in a statistically significant
 increased incidence of hepatocellular
 carcinomas and adenomas in female
 raU and both sexes of mic*.
 Additionally, there was a statistically
significant increase in the combined
incidence of neoplastic nodules and
hepatocellular carcinomas in high dose
male rats. The 13 factors presented in
the comment, to support the view that
DEHP does not have an appreciable
cancer risk, do not conclusively support
an absence.of cancerrisk to humans-' •. *
(see comment response document for
detailed discussion). The EPA approach.
i.e.. weight-of-evidence consideration
and non-threshold low-dose
extrapolation, is considered protective
of human health and EPA has concluded
that the weight of evidence for DEHP
warrants classification in Group  B2.
according to the EPA Guidelines  for
Carcinogen Risk Assessment. In most
cases, the Agency places Group B2
contaminants into EPA Category I and
sets MCLGa at zero when there is strong
evidence of carcinogenicity from
drinking water. EPA's policy is to set
MCLGs for Category I chemicals  at zero.
The fact that the European communities
have concluded that DEHP is not a
human carcinogen is noted, but it does
not necessitate that EPA adopt such a
position, especially in the context of
setting drinking water regulations
according to the strict standard in the
SDWA ("no known or anticipated"
human health effects with an "adequate
margin of safety"). After reviewing the
public comments. EPA has concluded
that an MCLG of zero, as proposed.
based on the available evidence of
carcinogenicity in animals, is
appropriate for DEHP.
  With regard to the comments on BBP.
EPA believes that to set an MCL for BBP
alone would incorrectly suggest (as
discussed above) that the available data
are not adequate to regulate DEHP as a
carcinogen. A DWEL for BBP was
determined based upon systemic toxic
effects to the liver, kidney, and testes.
When selecting a NOAEL. EPA does not
necessarily rely upon the conclusions
published with the study. The NOAEL
for BBP was based upon liver weight
change and the value selected was
corroborated by evidence from other
studies. The rationale for selecting the
NOAEL-can be reviewed in the health
criteria document for phthalates
[USEPA. 1991g]. An additional
uncertainty factor for limited cancer
evidence was incorporated to develop
the proposed MCLG for BBP; however.
the Agency is not finalizing the MCLG at
this time.
  Considering the toxicity. occurrence.
and exposure of DEHP and BBP.  EPA
has decided to regulate DEHP only
because it appears more likely to occur
in drinking weter and is more toxic.
Based  on the weight-of-evidence on

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31792       Federal  gagktar / Vol. 57. No. 138 / Friday. July 17.  1992 / Rulea  and Regulations
carcinogenicity. the Agency it
promulgating today an MCLG of zero for
DEHP. as proposed.
  f. Dinoseb. In the July 1990,proposal
(55 FR 30387], EPA proposed an MCLG
cf 0.007 mg/1 for dinoseb based on a
two-year study in rats [Hazleton. 1977).
A LOAEL of 1 mg/kg/day was identified
from1 this study. An uncertainty factor of
1.000 {as per NAS/EPA guidelines for a
LOAEL) was used in the derivation of
the DWEL of 0.035 mg/1. This LOAEL of
1 mg/kg/day was also supported by a
100-week mouse study [Brown. 1981]
and a 3-generation reproductive study in
rats (Irvine. 1981]. The proposed MCLG
was based upon this DWEL and an
assumed drinking water contribution of
20 percent of the total intake. Dinoseb
was placed in Category III (Group D)
based on the lack of evidence of
carcinogenicity.
  Publir Cjmmenls: One comment was
received on the health effects of
dinoseb. The commenter agreed with
EPA that dinoseb should be placed in
Group D (inadequate evidence of
carcinogenicity). However, this
commenter questioned the rationale for
using 1.000 instead of 100 as the
uncertainty factor in the calculation  of
the DWEL
  EPA Response: The Agency used an
uncertainty factor of 1.000 in the
calculation of the DWEL in accordance
with the NAS/EPA guidelines for use of
a LOAEL in the absence of a NOAEL
from an animal study. Therefore, based
on the available toxicological data for
dinoseb. EPA is promulgating  today an
 MCLG of 0.007 mg/1 for dinoseb. as
proposed.
  g. Dignat EPA proposed an MCLG of
0.02 mg/1 for diquat in the July 1990
proposal [55 FR 30389] following a
Category 111 approach. The MCLG of
0.02 mg/1 was derived from a chronic
feeding study in rats (Colley et al., 1985]
A NOAEL of 0.22 mg/kg/day was
identified from this study. A DWEL of
0,08 mg/1 was calculated by applying an
uncertainty factor of 100. The MCLG of
0 02 mg/1 assumes a drinking water
contribution of 20 percent of the total
intake. EPA has placed this contaminant
in Category HI based on the lack of
information on its carcinogeniciry. No
new data that would change the
conclusions presented in this notice
have become available since its
publication.
   Public Comments: EPA received one
 comment on the proposed MCLG for
 diquat The commenter indicated that an
 online computer search of the
 Hazardous Substances Data Base
 (HSDB) showed that diquat causes
 nausea, vomiting, diarrhea, possible
 liver and kidney damage, dyspnea, and
 pulmonary edema. The commenter also
 noted that diquat appears to affect
 epithelial tissues primarily and may
 attack those of the kidney or lens of the
 eye preferentially.
   EPA Response: EPA agrees with the
 commenter  that diquat causes the  above
 mentioned effects when used at high,  •
 doses in animal tests. These effects
 were discussed in the Health Criteria
 Document for diquat prepared in support
 of the July 1990 proposal [USEPA.  1990e:
 finalized as  USEPA. 1992g|. However.
 the effects reported in the Federal
 Register notice are effects associated
 with the critical endpoint of toxicity
 used  to establish the no-observed-
 adverse-effect level (NOAEL) for diquat.
 The effects described by the commenter
 are acute effects noted only at much
 higher dose  levels than the dose causing
 the critical effects described in the
.notice. Therefore, based on the
 available health information, the
 Agency is promulgating today an MCLG
 of 0.02 mg/1 for diquat as proposed.
   h. Endothall: EPA proposed an MCLG
 of 0.1 mg/1 for endothall in the July 1990
 proposal [55 FR 30390]. The MCLG was
 derived from a 24-month feeding study
 in beagle dogs [Keller. 1965). This study
 identifies a NOAEL of 2 mg/kg/day. A
 DWEL of 0.7 mg/l was derived for the
 70-kg adult by applying an uncertainty
 factor of-100 (in accordance with NAS/
 EPA guidelines). The MCLG for
 endothall was then calculated at 0.1 mg/
 1 by applying a 20 percent contribution
 from drinking water. EPA has placed
 this contaminant in Category in (Group
 D) based on the lack of adequate data
 on its carcinogenic potential. No new
 data that change the conclusions
 presented in this notice have become
 available since its publication.
   Public Comments: EPA received one
 comment on the proposed MCLG for
 endothall. This commenter indicated
 that there is a one-year dog study
 '[Greenough et al.. 1987] with a higher
 NOAEL of 6 mg/kg/day that the
 commenter believes would be more
 suitable for  the calculation of the
 reference dose than the 2 mg/kg/day
 NOAEL from the two-year dog study by
 Keller (1965) used by the Agency. He
 further indicated that the effects noted
 by the Agency in the Keller study
 (increased organ weight and organ-to-
 body weight ratios) are not in hit
 opinion, "clearcut adverse effects"
 because no  effects on body weight gain
 or food consumption were seen at  any
 dose  level.
   EPA Response: The Agency agree*
 with this commenter that the additional
 one-year dog study on endothall
 [Greenough et ah, 1987; MRID 4M074S2-
 02]. which waa not available at the time
 the MCLG was proposed, should be
 considered. The data from this study are
 summarized below.
  In a 12-month dietary study in dogs,
 disodium endothall was fed to groups of
 four male and four female beagle dogs at
 levels of 0.150. 450, or 1.350 ppm
 [Greenough-et al.v!967f.-After 6 weeks
 of dosing, the dietary level at the highest
 dose was reduced to 1.000 ppm because
 of anorexia, decreased food
 consumption and body weight  loss.
 Compound intake in the low-, mid- and
 high-dose groups was approximately 6.
 18 and 35.8 mg/kg/day endothall
 disodium. After the highest  dose had
 been reduced to 1.000 ppm.  a partial
 recovery of the weight loss was
 observed, but the overall weight gain
 remained lower than in controls. No
 effects on weight gain were observed at
 150 or 450 ppm. However, based on the
 histologic changes in the liver and
 reactive hyperplastic response in the
 gastric mucosa. the LOAEL  is 450 ppm
 (14.4 mg/kg/day endothall ion), and
 considering the marginal effects on the
 stomach at the lowest level, the NOAEL
 is probably slightly lower than 6 mg/kg/
 day endothall disodium (equivalent to
 4.8 mg/kg/day endothall  ion).
  The Agency notes that the lowest
 dose tested in the Greenough et al. dog
 study of 4.8 mg/kg/day endothall ion
 (150 ppm) provides supportive evidence
 that the noted low grade epithelial
 irritation may contribute  to more
 remarkable effects when the animals are
 exposed to endothall for a longer period
 of time ao noted in the two-year dog
 feeding study by Keller (1965). Although
no effects were observed on body
weight gains or on food consumption in
 the two-year dog feeding study
 [Greenough et al., 1987], the increased
weights and organ-to-body weight ratios
for the stomach and intestine in this
study were dose-dependent and must be
considered in the risk assessment of this
chemical, considering that It is an
irritant.
  The dog appears to b« more sensitive
to adverse effects from endothall than
 the other animal species tested (as
discussed in the proposal). EPA has
concluded that the Keller (1965) study is
 the most appropriate study based on the
effects noted above. Accordingly? the
Agency in promulgating today an MCLG
of 0.1 mg/1 for endothall. as proposed.
  i. Glyphoaate. EPA proposed an
MCLG of 0.7 mg/1 for glyphosate in the
July 1990 proposal (55 FR 30392]. The
MCLG of 0.7 mg/1 was derived from a
three-generation rat study (Biodynamics,
1961a]. This study showed a statistically
 significant Increase in kidney lesions.
The NOAEL was identified at 10 mg/kg/

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              Ftxferal Register / VoL S7. No.  138 / Friday. July 17. 1992 / Rules  and Regulations
 day. A DWEL of 3.5 mg/1 was derived
 by applying an uncertainty factor of 100.
 which is in accordance with NAS/EPA
 guidelines. The MCLG of 0'.7 mg/1 for
 glyphosate was calculated by applying a
 20 percent contribution from drinking
 water.
   Several additional, toxicity. studies on., .
 glyphosate submitted tc the Agency
 since publication of the July 1990 notice
 have been evaluated. However, these
 studies do not provide new information
 that would change the MCLG proposed
 in that notice. The proposal noted that
 EPA has classified glyphosate as a
 Category III (Group D) chemical. In
" Joday'a notice, the Agency still places
" "glyphosate in Category III (Group D) for
 establishing the MCLG.
   Public Comments: In response to the
 July 1990 notice, two individuals or
 organizations commented on the MCLG
 proposal for glyphosate. One commenter
 noted that over-exposure to glyphosate
 may result in mucous membrane
 irritation, abdominal pain, vomiting,
 hypertension, oliguria. and anuria. The
 other commenter  claimed that the July
 1990 notice did not document
 adequately the results of some of the
 toxicological studies with glyphosate
 and did not include the most recent data
 on this chemical,  such as a new two-
 generation rat reproduction study
 [Reyna. 1990), which concerned much
 higher doses than the 1981 three-
 generation rat study by Biodynamics
  that was used in establishing the
  proposed MCLG.  This commenter also
  claimed that the oral LD* in mice is 10
 g/kg and that information on the
  toxicokinetics of  glyphosate is not "very
  limited" as stated in the July 1990 notice.
  The commenter requested that the
  discussion of the  chronic rat study of
  1981b by Biodynamics be revised as
  follows:
    Because of the absence of a dose-
  dependent effect, the lack of preneoplastic
  changes, the wide variability in the
  spontaneous incidence of thil tumor, the
  similarity in incidence between the high dote
  group and historical controls, the lack of any
  evidence of genotoxicity. it was concluded
  that the observed incidence did not
  demonstrate an oncogenic response
  (emphasis added).

  and that the statement on the three
  generation rat study of 1981a by
  Biodynamics also be corrected to:
     In the three-generation rat reproduction
  study and addendum, the mott significant
 '"•' finding was  focal, unilateral, renal tubular
  dilation in the kidneys of male pup* for the
  ft* generation of high-dote d«m* (30 mg/kg/
  day). The NOEL for thii effect wit 10 mgykg/
  day. No effects on  fertility or nproducUv*
  parameters were noted" (emphasis added).
  EPA Response: In response to the first
commenter, the Agency notes that acute
effects are already discussed in the
Health Criteria Document for glyphosate
[USEPA. 19SOfl. The preamble to the
proposal generally discussed only
effects noted at the lowest effect level
and not the acute, toxicity effects that  ...
may occur at much higher dose levels.
  In response to the second commenter,
the Agency agrees to include the revised
language quoted above in the Public
Comment Response Document [USEPA.
1992aj with respect to both the three-
generation rat reproduction study
[Biodynamics, 1981a] and the chronic rat.
study [Biodynamics. 1'98'lb], The Agency
believes that this-revised language is
appropriate. It does not change the
bases for the MCLG. The criteria
document [USEPA. lSS2bJ discusses
these issues in detail.
  On reconsideration, the Agency'
agrees with this commenter that the
data on the toxicokinetics of glyphosate
is not "very limited". The available
information as documented in the
updated Health Criteria Document for
glyphosate (1991) indicate the 97.5
percent of the absorbed dose by rats is
eliminated in urine and feces. The alpha
half-lives ranged from 2.11 to 7.52 hours
for males and 5 to 6.44 hours in females
while the beta half-lives ranged from 69
to 181 hours and 80 to 337 hours for
males and femates, respectively.
  In response to the commenter's
statement that the LEWi in mice is 10 g/
kg, a lower LDw in mice of 1.6 g/kg was
reported by Bababunmi et al. (1978), as
noted in the proposal.
  The Agency also notes that a new
lifetime rat feeding study [Stout and
Ruecker, 1990, MRID #416438-01.
volumes 1-6] was recently submitted to
the Agency and is being reviewed. As
per the commenter's recommendation to
use the new two-generation rat study
 [Reyna, M.S..  1990, MRID #416215-01).
for the  MCLG calculations, this study
was submitted to the Agency only
 recently and is fully described in the
 updated Health Criteria Document
 [USEPA. 1992b| prepared in support of
 today's rule. This new study is still
 under evaluation by the Agency. It i»
 unlikely that this study wiO be
 considered an appropriate basis for the
 NOAEL and MCLG because the NOAEL
 in this  study is 500 mg/kg/day, whereas
 adverse effects were noted at a much
 lower dose level (30 mg/kg/day) in the
"three-generation reproduction study In
 rats [Biodynamics, 1881a).
   Therefore. EPA has concluded that the
 three-generation study in rat*
 [Biodynamics, 1981a| is appropriate for
 the derivation of the MCLG for
 glyphosate. and is promulgating today
an MCLG of-0.7 mg/1 for this
contaminant, as proposed.
  j. Hexachlorocyclopentadiene (HEX).
EPA proposed an MCLG of 0.05 mg/1 for
hexachlorocyclopentadiene in the July
1990 proposal [55 FR 30394). The MCLG
of 0.05 mg/1 was derived from a 13-week
oral toxicity study .in rats. (SRL 1981).. •••-•
The only effect reported was slight
depression of body weight. A NOAEL of
10 mg/kg/day was identified from this
study. A DWEL of 0.25 mg/1 was
calculated by applying an uncertainty
factor of 1.000. which is appropriate for
use with a NOAEL derived from animal
study data that are significantly less-
than-lifetime in duration. The MCLG of
0.05 mg/lwas calculated from the
DWEL of 0.025 mg/1 by applying 20
percent  contribution from drinking
water. No new data that would change
the conclusions presented in this notice
have become available since  its
publication.
  Public Comments: EPA received one
comment on the proposed MCLG for
hexachlorocyclopentadiene in the July
1990 notice. The commenter indicated
that the toxicity data in the SRI study
are inadequate to justify setting an
MCLG and suggested that EPA postpone
regulation of hexachlorocyclopentadiene
until adequate toxicity studies are
available.
  EPA Response: Although EPA realizes
that the toxicity data base  is not as
extensive as-for some contaminant*.
EPA believes that there are sufficient
toxicity data to regulate
hexachlorocyclopentadiene. The SRI
data were reviewed by the Agency's
Reference Dose (RID) Workgroup, which
verified the Reference Dose using these
data. In addition. EPA is required by the
1988 amendments to the SDWA to
regulate hexachlorocyclopentadiene.
Therefore, based on the available data.
the Agency U promulgating today an
MCLG of 0.05 mg/1 for
hexachlorocyclopentadiene, as
proposed.
   k. Simazine. EPA proposed an MCLG
of 0.001 mg/1 for simazine  in the July
1990 proposal [55 FR 30402). The MCLG
was derived from a DWEL of 0.058 mg/1
(rounded to 0.06 mg/1), applying a 20
percent contribution from drinking
water and an additional 10-fold safety
factor by considering the classification
of simazine in Category II (limited
evidence of carcinogenicity from
drinking water). The MCLG was based
upon a  NOAEL of 0.5 mg/kg/day for
non-carcinogenic effects in a 2-year rat
chronic feeding/oncogenic study
 [McCormick et aL, 1988, MRID #406144-
05) and was supported by  a NOAEL of
0.7 mg/kg/day in a 1-year  dog feeding

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 31794       Federal Register / Vol. 57. No.  138 / Friday, July 17. 1992 / Rules and Regulations
 study [McCormick and Green. 1988,
 MRID =406144-021-
   Several uncertainty factors were
 applied to this NOAEL: 10-fold to
 account for mterspecies extrapolation
 and another 10-fold to account for
 intraspecies variability, plus an
 additional 3-fold factor to account for
 the absence of an adequate study (data'-
 gap) to assess the potential toxic effects
 of simazine on reproduction. The
 proposal also indicated that if '.he data
 gap  for reproduction is filled before
 finalizing the simazine  MCLG and if the
 data from this study would not raise any
 specific lexicological concerns at the
 dose used in the calculation of the
 MCLG. 0.5 mg/kg/day. the 3-fold
 uncertainty factor may be dropped and
 the DWEL would then be 0.2 mg/1 and
 the MCLG would be 0.004 mg/1 [55 FR
 30404. footnote]. This MCLG lies in  the
 range of 10"l cancer risk estimates.
   As noted in the November 29.1991
 Notice of Availability, subsequent to the
 July 1990 proposal, the data gap •
 concerning reproduction effects has
 been filled. The Agency recently
 received  a two-generation rat
 reproduction study [Eps'tein. 1991. MRID
 =418036-01] where simazine was tested
 at 10,100 and 500 ppm (these doses  are
 equivalent to 0.5. 5 and 25 mg/kg/day
 using Lehman (1959} conversion from
 ppm to mg/kg/day) assuming rats
 consume 5 percent of their body weight
 daily. No effects were noted in this
 reproduction study at the dose level (0.5
 mg/kg/day) used to calculate the MCLG.
 In light of these  data. EPA indicated in
 the Notice of Availability of November
29.1991 that it was considering dropping
 the 3-fold uncertainty factor from the
 calculation of the DWEL and the MCLG
 for simazine as EPA had indicated it
 would do in the proposal [55 FR 30404.
 Footnote]. EPA has now decided in
 today's final rule to drop the 3-fold
 uncertainty factor. Accordingly, the
 proposed DWEL end MCLG of 0.06 and
 0.001 mg/U respectively, are modified
 and finalized (after rounding) at 0.2 and
 0.004 mg/1. respectively.
  Public Comments: Two individuals or
 organizations commented on the MCLG
 for simazine. One commenter
 questioned  the reliability of the current
 animal studies for simazine if the
Agency haa to use an additional 3-fold
 uncertainty factor in the calculation of
 the DWEL. This commenter was also
 concerned that the chemical may have
been placed in Group C (possible human
 carcinogen) based on the similarity
between simazine tnd atrazine or
propazine. He claimi that the
Justification for the cancer classification
of simazine being placed in Group C
  should be made solely on the basis of
  animal data.
    The second commenter agreed that
  EPA should use the non-carcinogenic
  data for establishing the MCLG for
  Group C chemicals. This commenter
  added that Group C contaminants are
  not suitable for.the quantitative cancer
' • riskassessmenfprocess. "••' -
    Several comments on the NOA were
  received which discussed this issue. All
  of the commentere on the NOA
  supported use of the Epstein study
  [Epstein et al.. 1991] and dropping the
  additional 3-fold uncertainty factor.
    EPA Response: In response to the first
  commenter. EPA believes that the
  animal studies used in the calculation of
  the DWEL for simazine are adequate
  studies and provide reliable information
  to calculate the DWEL. The additional 3-
  fold uncertainty factor was originally
  applied to account for the absence of an
  adequate reproduction study. As
  discussed above, the 3-fold uncertainty
  factor is not being used in the final
  DWEL or MCLG calculation in today's
  notice.
    As tj this commenter's concern that
  simazine should be placed in Group C
  based only on animal data and not on
  the similarity with atrazine or
  propazine. the Agency notes that
  simazine has been placed in Category II
  based on the weight-of-evidence
  approach and not only because of the
  structure-activity relationship with
  atrazine and propazine. Simazine has
  been found to cause mammary gland
  tumors in Sprague-Dawley rats. This
  effect was also noted with other
  analogues: atrazine. propazine, and
 recently with cyanazine. This fact adds
  to the weight-of-evidence of the
 carcinogenicity of simazine in this
• animal species and supports EPA's
 classification of simazine in Group C.
   In response to the second
 commenter's contention that all Group C
 contaminants are unsuitable for
 quantitative cancer risk assessment, the
 Agency disagrees. In some cases,
 adequate dose-response data from •
 singk study may be available, even
 though the weight of evidence is
 inadequate for a Group B classification.
   In the July 1990 proposal the Agency •
 described two options for the
 calculation of the MCLG for Category II
 (i.e.. Group C) contaminants such aa
 simazine, one using the RfD approach.
 with an additional safety factor, and
-another using the cancer quantification
 approach.
   Many drinking water contaminants
 placed in Category D have been
 classified aa Group C, possible human
 carcinogen, due to the limited nature of •
  the weight of evidence for
  carcinogenicity. For Group C. the
  existing cancer risk assessment
  guidelines [USEPA. 1986] allow some
  flexibility as to whether to quantify the
  risk. Quantification should be carried
  out on a case-by-case basis, depending
  on various factors, including'th*--.-
  adequacy of the data.
    For Group C contaminants, the MCLG
  is usually based on the RfD approach
  when sufficient non-carcinogenic data
  are available. An additional 1- to 10-fold
  safety factor is used to account for the
  possible carcinogenicity. The resulting
  MCLG can then be compared to the
  cancer risk if the data are quantifiable.
  If adequate data are not available to
  determine an RfD. then the MCLG is set
 at the 10'* to 10"»excess cancer risk
 level where such quantification is
 appropriate.
   EPA under FIFRA examines the risk
 for Group C contaminants like simazine
 using both an RfD approach and
 quantification of cancer risk using the
 cancer potency. Either method may be
 an appropriate method for risk
 management decisions.
   As noted in the July 1990 proposal,
 carcinogenic potency for simazine at 1.2
 X 10"' mg/kg/day"' was determined
 from the incidence of mammary gland
 tumors in female Sprague-Dawley rats
 [McCormick et al., 1988: MRID *4O6144-
 05). Based on this carcinogenic potency,
 simazine concentrations of 0.003 and
 0.0003 mg/1 were associated with
 theoretical cancer risk levels of 10"* and
 10"*, respectively.
   The Agency also-has sufficient non-
 carcinogenic data to determine an RfD.
 Using the RfD and a 10-fold safety
 factor, EPA calculated an MCLG of 0.004
 mg/1. This MCLG corresponds to a
 theoretical cancer risk level of 1  X 10~*.
 The 10-fold safety factor used by EPA to
 calculate this MCLG is justified based
 on the possible cancer risk associated
 with this chemical as expressed in the
 rat chronic/oncogenic study
 [McCormick et al., 1988; MRID #406144-
 05]. Thin study was used for both the
 calculation of the cancer potency based
 on mammary gland tumors and the
 derivation of the RfD based on a
 NOAEL of 0.5 mg/kg/day  for other
 systemic toxicity. like the  noted
 reduction in the female body weight
gain and the significant changes in the
hematology parameters. This RfD is also
supported with the NOAEL of 0.7 mg/
kg/day from a one-year dietary
exposure study in the dog [McCormick
and Green. 1988; MRID #406144-02].
  Using the RfD approach with an
additional safety factor, the Agency is
promulgating today an MCLG of 0.004

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             F*dervi Register / VoL 57, No.  138 / Friday. July 17, 19&2 / Rules and Regulation*	3TT33
tng/1 for simazine assuming a daily
consumption of 2 liters of water by a 70
kilogram adult and applying a 20 percent
relative source contribution from
drinking water. This MCLG of 0.004 mg/1
corresponds to the theoretical cancer
risk level of 1 X 10"*.
  1. l'2.4-Trichlorobenzene. EPA
proposed *n MCLG of 0.009 mg/1 forv
1.2.4-trichlorobenzene (TCB) in the July
1990 proposal [55 FR 30405). The MCLG
of 0.009 mg/1 was derived from a
subchronic inhalation study in rats
{Watanabe et al.. 1978). A  NOAEL of
1.31 mg/kg/day and a DWEL of 0.046
mg/1 were identified, resulting in an
MCLG of 0.009 mg/1 when applying a 20
percent contribution from  drinking
water.
   Public Comments: In response to me
July 1990 notice, three individuals or
organizations commented  on the MCLG
 proposed for 1.2.4-trichlorobenzene.
Each commenter criticized EPA's use 'of
 an inhalation study to derive a health
 assessment value and regulatory
 standard for drinking water ingestion.
   EPA Response: In response to the
 public comments received for the July
 1990 proposal. EPA has reexamined the
 database for trichlorobenzene. The
 Agency agrees with the public
 comments stating that in the case of
 1.2,4-trichlorobenzene the oral RfD
 should not be based upon the Watanabe
 inhalation study [Watanabe et al., 1978).
 Upon reexamination of the oral studies,
 EPA determined that the Robinson et al.
 (1981) study provides the  best scientific
 basis for determination of an RfD for
 1.2.4-trichlorobenzene, as discussed in
 the November 1991 Notice of
 Availability [56 FR 60953]. This study
 was a multi-generation reproductive
 study in rats that were dosed with 0, 25.
 100 and 400 ppm 1.2.4-trichlorobenzene
 added to the drinking water for 95 days
 per generation for two generations and
  examination  of the offspring of the Fi
  rats. The only compound-related.
  changes seen in the dams or offspring
  were significant increase* in adrenal
  gland weights of the Po and Ft
  generations.
    To more specifically characterize the
  changes noted in this study, an in-house
  EPA study was performed. It was found
  that the increased adrenal weights were
  associated with the histopathologic
  lesion, vacuolization of the zona
  fasciculata of the cortex. The Robinson
  study determined a NOAEL at the 100.
.  ppm dose (14.8 mg/kg/day). Based on
 .  thi* study antf applying an uncertainty
  factor of 1,000 to account for sensitive
   human subpopulatiotic, extrapolation
   from an animal study, and for use of a
   study which was lew than lifetime, the
   RfD is 0.01 mg/kg/day and the DWEL is
0.35 mg/1 (verified by the RfD/RfC
Workgroup [USEPA. 1991bJ). Applying
relative source contribution of 20
percent. EPA is today promulgating an
MCLG of 0.07 mg/1 based upon the
Robinson study, as proposed in the
Notice of Availability,
  EPA received two comments on the
NOA.1 both of which supported EPA't '•'
use of the Robinson study [Robinson et
al.. 1981] as the basis for the 1.2.4-
trichlorobenzene RfD and MCLG.
  m. 1.1.2-Trichtoroethane. EPA
proposed an MCLG of 0.003 mg/1 for
1.1.2-trichloroethane in the July 1990
proposal [55 FR 30406]. The MCLG of
0.003 mg/1 was derived from two 90-day
drinking water studies in mice [Sanders
et al.. 1985: White et al.. 1985]. A NOAEL
value of 3.9 mg/kg/day was used to
calculate a DWEL of 0.14 mg/1. by
applying an uncertainty factor of 1.000
(per NAS/EPA guidelines for a NOAEL
derived from a less-than-lifetime study).
The proposed MCLG of 0.003 mg/1 was
calculated from the DWEL by applying
an additional safety factor of 10 because
of the classification of 1.1.2-        >
trichloroethane in Group C (limited
evidence of carcinogenicity as
evidenced by the presence  of
hepatocellular carcinomas and adrenal
 pheochromocytomaa in mice but not
 rats) and by applying 20 percent
 contribution from drinking water.
   Public Comments: In response to the
 July 1990 notice, two individuals
 commented that the use of an
 uncertainty factor of 1.000 indicated that
 reliable data do not exist for the
 development of a DWEL. Another
 commenter was confused about the use
 of an extra 10-fold safety factor for a
 chemical classified as a Group C
 chemical and asked ifor clarification
 about the use of an extra safety factor
 and the rationale for its use.
   EPA Response: In response to the
 comments about the use of a 1.000
 uncertainty factor. EPA prefers to use
 data from lifetime studies to set DWELs
 and MCLGs. However. EPA often
 regulates chemicals that do not have a
 complete data base: for example, there
 may be no lifetime studies in animal
 species. In such cases, an additional 10-
 fold uncertainty factor is applied to
 account for the "data gap." per NAS/
 EPA guidelines.
    As described previously in today'*
 notice. EPA has developed a three-
 category approach for setting MCLGs for
  chemical* in drinking water. For
  chemical* in Category II (compound*
  having limited evidence or
  carcinogenicity via drinking water), the
  MCLG it usually bated on the use of the
  RfD approach with an additional safety
  factor of 1 to 10 to account for possible
carcinogenicity. If the data are not
sufficient to calculate an RfD, then the
MCLG is set in the 10'»to KT • lifetime
cancer risk range. Since the Agency has
verified an RfD for 1.1.2-trichloroethane
(verification date 8/01/90) [IRIS. 1991hj.
EPA has used the RfD approach with an
additional safety factor of 10 (to account-
for possible carcinogenic effects) to
derive the MCLG for 1.1.2-
trichloroethane. Based on this approach
and after consideration of public
comment. EPA is promulgating  today an
MCLG of 0.003 mg/1 for 1.1.2-
trichloroethane. as proposed. This
MCLG of 0.003 mg/1 corresponds to the
theoretical cancer risk of 10' *.
   n'. 2.3,7.8- Tetrachlorodibenzo-p-dioxin.
EPA proposed an MCLG of zero for
2.3.7.8-tetrachlorodibenzo-p-dioxin
(2,3.7.8-TCDD: dioxin) in the July 1990
proposal (55 FR 30384). This proposal
MCLG was based on the classification
of 2.3.7.8-TCDD in Group B2: probable
human carcinogen. New data [i.e..
Fingerhut et al.. 1991 and other studies]
have become available to EPA since the
publication of the July 1990 notice.
• Critical reviews of much of these data.
including reassessments of critical
cancer studies and new epidemiology
studies are under way but have not been
completed by the Agency to date. The
Agency is undertaking a complete
reassessment of the risks from dioxin
which includes a review of the entire
health effects data set for 2.3.7.8-TCDD  .
 as well as additional laboratory studies.
The Agency expects to complete its
 reassessment including a full peer
 review by 1993.
   Until that time, the Agency believes it
 is appropriate to proceed to regulate
 2.3.7.8-TCDD in drinking water using the
 existing health data and the current
 peer-reviewed risk assessment.
 Consequently, the Agency is regulating
 2.3.7.8-TCDD based on the risk
 assessment presented  in the July 1990
 proposal. Once  EPA has completed its
 critical review of the new health
 information, the Agency will initiate a
 process to determine whether  the MCLG
 for 2.3.7.8-TCD should be revised.
   Public Comments: In response to the
 notice of July 1990.12 individuals or
. organizations commented on the MCLG
 proposal for 2.3.7.8-TCDD. Several
 commenters believed EPA's proposed
 MCLG was too stringent and several
 believed the MCLG was appropriate, but
 that the MCL was too lenient.
   Four commenters believe that the
 cancer potency of 2.3.7.8-TCDD ha*
 been overstated by the Agency and
 cited the re-review of the Kociba cancer
 slides by the EPA Pathology Working
 Group (PATHCO) as evidence [Kociba

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             F«hrd Registtg / Vol. 57. No. 138 / Friday. July 17. 1992 / Rules and  Regulations
et al.. 1978J. The PATHCO'* panel of
experts found two-third* fewer tumort
than the original Kociba study, and
concluded that those found were
correlated with toxicity. suggesting a
threshold mechanism. These
commenters also indicated that the
PATHCO findings have already been
recognized by.EPA as scientifically ••
defensible since the Agency approved
the Maryland Water Quality Standard.
which relied on these findings.
  One commenter staled that there is a
large body of epidemiological evidence
on 2,3.7.8-TCDD which has found no
association between dioxin and human
cancer, and that the Agency is therefore
not justified in basing all its
mathematical extrapolations on cancer
data from rat studies. This commenter
also stated that the linear multistage
model  used to qualify cancer risk for
2.3.7.8-TCDD was the incorrect model
since the reexammatSon of the Kociba et
al. (1978) data indicates no linear dose
response and evidence of a threshold
cancer response.
  The same commenter urged  EPA to
revise  the cancer potency factor based
on the most recent reexamination of the
Kociba et al. (1978) data done  by the
PATHCO.
  Two commenters criticized the fact
that the MCLG/MCL applies only to
2.3.7.8-TCDD. even though the Agency
acknowledges that other isomer* of
polychlonnarted dibenzo-p-dioxin
(PCDD) and polychlorinated
dibenzofurans (PCDF) have similar toxic
properties as estimated by the 2.3.7.8-
TCDD toxic equivalency factor (TEF)
methodology. The commenter  claims
that the MCLG/MCL should be based on
the TEF approach.
  One commenter believes that EPA's
proposal of a zero MCLG for 2,3.7,8-
TCDD is inappropriate since data
indicate that the chemical promotes
cancer through a receptor mediated
mechanism, thus indicating it  is a
threshold carcinogen. The commenter
indicated that 2.3.7.8-TCDD is not a
tumor initiator but is more likely a tumor
promoter.
   One commenter stated that  the
average dioxin exposure among the
general population exceeds EPA's
 calculated reference dose (RfD) and that
 it is unacceptable for EPA to allow any
 further dioxin exposure. The commenter
 also stated that the Agency failed to
 consider more recent data showing
 adverse reproductive effects for 2.3.73-
TCDD at doses' lower than those cited in
 the July 1990 proposal The commenter
 claims that an up-to-date RfD would be
 10 times more stringent than the RfD
 cited in the July 1990 proposal. •
  EPA Response: EPA disagree* with
the commenters who stated that the
MCLG for 2.3.7.8-TCDD is too stringent.
The Agency has placed this compound
in Category I and is setting the MCLG at
zero based on its carcinogenic potential.
  EPA disagrees with the commenters
who alleged that EPA has already
approved- the Kociba- et at (1978) re'read-
as part of its approval of the Maryland
water quality standard for 2.3.7,8-TCDD.
Maryland did not incorporate a re-read
of the Kociba study in developing their
water quality standard for 2.3.7.8-TCDD.
Instead. Maryland used the FDA cancer
potency estimate for this contaminant.
  In response to the concerns raised
about the cancer potency, EPA is
presently reviewing the cancer potency
of 2.3.7.8-TCDD as part of its complete
reassessment of dioxin. The Agency is
also investigating the mechanism of
carcinogenicity, including assessing the
likelihood of a potential threshold
mechanism and appropriateness of the
current extrapolation model. However,
at this time, the Agency has not
completed its risk assessment or
subjected it to peer review and therefore
has made no decisions to change its
assessment of the cancer potency or the
possible threshold mechanism for
dioxin. As stated above, the Agency
expects to complete its reassessment in
1993. Given this time frame and the legal
mandate to regulate  2,3.7,8-TCDD in
drinking water, the Agency has relied on
the data available at the time of the July
1990 proposal.
  EPA does not agree with the
commenter who stated that there is a
large body of epidemiology data on
2.3.7,8-TCDD which has found no
association between dioxin and human
cancer. EPA stated in the July 1990
proposal that taken together, the
epidemiology studies based on exposure
to 2,3,7.8-TCDD by themselves are
inadequate to establish a relationship
between 2,3.7.8,-TCDD and the
development of tumors in humans. More
recent data, however (including
Fingerhut 1991 and studies from
Germany and Italy), are being evaluated
together with the previous epidemiology
studies a* part of the overall
reassessment of dioxin. and EPA
expects to reach its conclusion* within
the timeframe noted above.
  EPA is considering revising the cancer
potency based on the re-read of tht
Kociba et al. (1978) data'and other data
such as body weight/surface area
correction*. In addition. EPA will asws*
the entire data base, including the uuuc
of threshold carcinogenicityt and    • :
possible  immuBotoxicity and
reproductive toxicity at low levels,
before embarking on a change in lite
 cancer risk characterization. Because
 dioxin is currently considered a B2
 carcinogen by the Agency, the MCLG is
 being set at zero.
   EPA agrees that new data published
 since development of the proposed
 criteria document might support a
 different RfD. As part of an overall .   .
' reassessment of dioxin toxicity. EPA i*
 reviewing  studies on immunotoxicity
 and reproductive effects in addition to
 the cancer data. The RfD and  DWEL
 would become relevant to setting the
 MCLG for  dioxin only if it were
 determined that this compound is in fact
 a threshold carcinogen with a potency
 so low that other non-cancer effect*
 become the mo'st sensitive endpoints of
 toxicity. This point will be considered in
 the re-evaluation of the risk assessment
 of 2.3.7.8-TCDD.
   In response to the commenter who
 stated that EPA should regulate  all
 isomers of polychlorinated dibenzo-p-
 dioxin (PCDD) and polychlorinated
 dibenzofurans (PCDF) using the  tox'ic
 equivalency factors (TEF) approach.
 EPA is not considering the regulation of
 other related compounds at this  time.
 The Agency has no indication that these
 compounds are found in public water
 supplies. The Agency is regulating
 2,3.7,8-TCDD in today's rule because it
 is the most potent isomer and  it is
 included in the list of 83 contaminants to
 be regulated under the SOW A.
   In response to the claim that EPA
 should not propose an MCLG of zero for
 2.3,7,8-TCDD because it is a threshold
 carcinogen, the Agency's reassessment,
 again, is reviewing all the health effects
 data on 2.3.7,8-TCDD in an effort to
 update the cancer risk characterization
 of 2,3.7,8-TCDD. However, until the
 Agency has completed its reassessment,
 the Agency will continue to consider
 2.3,7,8-TCDD to be a non-threshold
 contaminant and. thus, maintain an
 MCLG of zero for 2.3.7.8-TCDD. Because
 the analytic limitation for drinking water
 compliance monitoring for dioxin is at
 30 ppq, a significant change in the risk
 assessment and consequently the
 MCLG, would be needed before an
 increase in the final MCL would result
   Detailed descriptions of 2.3.7.8-TCDD
 toxicity at different dose levels and in
 different animal species are documented
 in the 2.3,7,8-TCDD Health Criteria
 Document  prepared in support of thi*
 regulation  [USEPA. 1988d]. Thi*
 document  i* available in the Drinking
 Water Public Docket
   Bated on the available information.
 EPA is promulgating today an ViCLC of
 zero for 24,7.8-TCDD,
   o. Endrin, hexachlorobenzene,
 oxamyL pichram. For four

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              Federal Renter / Vol.  57.  No. 138 / Friday. July 17. 1992  /  Rules and Regulations       3179',
 contaminants, no significant issues were
 raised and no new health effects
 information was obtained by the Agency
 that would cause it to change the
 MCLGs from the level proposed in July
 1990. Therefore, for these contaminants
 (endrin. hexachlorobenzene. oxamyl and
 pidoram). final MCLGs are.promulgated
 in today's^otice as proposed, as
 presented in Table 2.

 B. Establishment of MCLs

 1. Methodology for Determination of
 MCLs

    The SDWA directs EPA to set the
 MCL "as close to" the MCLG "as is
 feasible." The term "feasible" means
 "feasible with the use of the best
 technology, treatment techniques, and
 other means, which the Administrator
 finds, after examination for efficacy
 under field conditions and not solely
 under laboratory conditions, are
 available (taking costs into •
 consideration)." {SDWA section
 1412(b)(5)). Each National Primary
 Drinking Water Regulation that
 establishes an MCL lists the technology.
 treatment techniques, and other means
 which the Administrator finds to be
 feasible for meeting the  MCL (SDWA
 section 1412(b)(6)).
    The present statutory standard for
 "best available technology" (BAT) under
 1412(b)(5) represents a change from  the
 provision prior to 1988, which required
 EPA to judge feasibility on the basis of
 "best technologies generally available"
 (BTGA). The 1988 Amendments to the
 SDWA changed BTGA to BAT  and
  added the requirement that BAT must
 be tested for efficacy under field
 conditions, not just under laboratory
  conditions. The legislative history  .
  explains that Congress removed the
  term "generally"  to assure that MCLs
  "reflect the full extent of current
  technology capability" [S. Rep. No. 58,
  99th Cong.. 1st Sess. at 8 (1985)]. Read
  together with the legislative history.
  EPA has concluded that the statutory
  term "best available technology" is  a
  broader standard than "best technology
  generally available." and that this
  standard allows EPA to select a
   technology that is not necessarily in
  widespread use.  as long as its
  performance has been validated in a
   reliable manner. In addition. EPA
   believes that the technology selected
   need not necessarily have been field
.   tested for each specific contaminant but
   rather, that the operating conditions
   may b« projected for a  specific
   contaminant using a field tested
   technology from laboratory or  pilot
   systems data.
  Based on the statutory directive for
setting the MCLs, EPA derives the MCLs
based on an evaluation of (1) the
availability and performance of various
technologies for removing the
contaminant, and (2] the costs of
applying those technologies. Other
technology factors that are considered .
in determining the MCL include the
ability of laboratories to measure
accurately and consistently the level of
the contaminant with available
analytical methods. For Category I
contaminants, the .Agency also
evaluates the health risks that are
associated with various levels of
contaminants, with  the goal of ensuring
that the maximum risk at the MCL falls
within the 10" * to 10"' risk range that the
Agency considers protective of public
health, therefore achieving the overall
purpose of the SDWA.
  EPA's initial step in deriving the MCL
is to make an engineering assessment of
technologies that are capable of
removing a contaminant from drinking
water. This assessment determines
which of those technologies are "best."
EPA reviews the available data to
determine technologies that have the
highest removal efficiencies, are
compatible with other water treatment
processes, and are not limited to a
particular geographic region.
  Based on the removal capabilities of
the various technologies. EPA calculates
the level of each contaminant that is
achievable by their application to large
systems with relative clean raw water
sources. [See H.R. Rep. 1185. 93rd Cong..
2nd Sess. at 13 (1974); 132 Cong. Rec.
S6287. May 21,1988, statement of Sen.
Durenberger.J
  When considering costs to control the
contaminants in thin rule, EPA analyzed
whether the technology is reasonably
affordable by regional and large
metropolitan public water systems [See
H.R. Rep. No. 93-1185 at 18 (1974) and
132 Cong. Rec. S6287 (May 21.1986)
(statement of Sen. DurenbergerJJ. EPA
also evaluated the total national
compliance costs for each contaminant
considering the number of systems that
will have to install treatment in order to
 comply with the MCL. The resulting
 total national costo vary depending
 upon the concentration level chosen as
 the MCL. The more stringent the MCL.
 the greater the number of systems that
 may have to Install BAT in order to
 achieve compliance and the higher the
 national cost In today's rule. EPA has
 determined that coits for large syjtems
 and total national compliance costs at
 the final MCL* are reasonable.
 affordable and. therefore, feasible.
   One commenter urged EPA to apply
 cost-effectiveness analysis in selecting
 the MCLs for the contaminants m this
 rule. EPA did consider the relative cost-
 effectiveness of regulatory alternatives
 in selecting the proposed MCLs for
 radionuclides in a recent notice (July 18.
. 1991 (56 FR 33050}). In. the-radionuclides-:-:
 proposal. EPA collectively analyzed the
 regulated contaminants based on the
 fact that all cause cancer by delivering
 ionizing radiation to body tissue.
 Ionizing radiation is itself classified as a
 group A carcinogen. Comparing the
 relative cost effectiveness of controlling
 different sources of ionizing  radiation
 dose formed the basis for choosing the
 most cost-effective alternative for
 proposal in the radionuclides rule. While
 EPA sought public comment on broader
• use of cost-effectiveness  analysis, the
 Agency did not suggest that  it would be
 applying a similar analysis to all other
 drinking water regulations, and EPA
 does not believe that cost-effectiveness
 analysis should be applied to the MCL
 selections in  today's rule since the
 factors that made this analysts
 appropriate in the radionuclide proposal
 radionuclides notice are not present
 here.
   The feasibility of setting the MCL at a
 precise level  is also influenced by
 laboratory ability to measure the
 contaminant  reliably. EPA derives
 practical quantitation levels (PQLs)
 which reflect the level that can be
 measured by good laboratories under
 normal operating conditions with
 specified limits of precision and
 accuracy. Because compliance with the
 MCL is determined by analysis with
 approved analytical techniques, the
 ability to analyze consistently and
 accurately for a contaminant at the MCL
 is important to'enforce a regulatory
 standard. Thus, the feasibility of
 meeting a particular level is affected by
 Jhe ability of analytical methods to
 determine with sufficient precision and
 accuracy whether such a level is
 actually being achieved. This factor is
 critically important in determining the
 MCL for contaminants for which EPA
  sets the MCLG at zero, a number of
  which by definition can be neither
  measured nor attained. Limits of
  analytical detection require that MCL be
•  set at some level greater than the MCLG
  for these contaminants. In these cases,
  EPA examined the  treatment capability
  of BAT and the accuracy of analytical
  techniques as reflected in the PQL to
  establish the appropriate MCL level
    EPA also evaluates the health risks
  that are associated with various
  contaminant levels in order to ensure
  that the MCL adequately protects the

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31798       Federal Register  /  Vol. 57. No.  138 / Friday. July 17. 1992 / Rules  and Regulations
public health. For drinking water
contaminants. EPA sets a maximum
reference risk range of 10"' to 10"*
excess individual risk from a carcinogen
over a lifetime. This policy is consistent
with other EPA regulatory programs that
generally target 'his range using
conservative models that are not likely
to underestimate the risk-Since the  •-.- ••
underlying goal of the Safe Drinking
Water Act is to protect the public from
adverse effects due to drinking water
contaminants. EPA seeks to ensure that
the health risks associated with MCLs
for carcinogenic contaminants are not
significant.
  Below is a discussion of how today's
MCLs were determined, including the
Agency's response to comments on the
proposed rule.
2. Inorganic Analytical Methods
  In the fi.ly 1990 notice, the Agency
proposed a list of analytical methods for
measuring the five inorganic chemicals
(lOCs) in today's ru'p. These analytical
 methods are considered to be
 economically and technologically
 feasible for compliance monitoring. In
 the November 29.1991 notice of
 availability (NOA). new information
 received by the Agency on these
 methods was made available for public
 comment. The NOA included new and
 updated versions'for analytical methods.'
 performance data on the proposed
 methods and corrections to some of the
 information included in the proposal
 related to the method detection limits.
 The NOA also addressed several issues
 that were raised during the public
 comment period for the July 1990
 proposal. EPA has analyzed the
 available information and has
 considered the public comments on the
 proposal and the NOA in arriving at the
 final selection of the inorganic methods
 and their associated MDLs and PQLs.
   The analytical methods being
 promulgated today are in some respects
 revised from those proposed, as
 indicated in the NOA. and as discussed
 below. These methods were selected
 based on the following factors: (l)
 Reliability (i.e.. precision/accuracy) of
 the analytical results; (2) specificity in
 the presence of interferences; (3)
 availability of enough equipment and
 trained personnel to implement a
 national monitoring program (i.e.... • ->• •••
 laboratory availability); (4) rapidity of
 analysis to permit routine use; and (5)
 cost of analysis to water supply
 systems.
   Table 11 lists the analytical methods
 that EPA is approving today for use  to
 comply with  the monitoring
 requirements in this rule. EPA has
 updated the references to the most
 recent editions of the relevant manuals.
 including the atomic absorption.
 emission, and mass spectrometric
 methods for metals, the spectrometric
 and electrode methods for cyanide.
 These newer editions are generally very
 similar, and in some cases identical, to
 the methods proposed in the Juiy 1990
 notice.
         TABLE 11.—APPROVED METHODOLOGY FOR INORGANIC CONTAMINANTS AND METHOD DETECTION LIMITS (MDLs)
                                                        Method
                                                                                                          MOL (mg/ n
Antimony ,



B«ytl«im ,.



NlCHW . .... „



Th4*i«m .....


C»arKje .....




, Atomic acsorption. Furnace 	 	 _ 	 _ 	
' Atomic Absorption. Platform 	 _ 	 _ 	 _ 	
i CP-Mast Soectromatry 	 v 	 _ ... ,
HyarKJe-Atomic Absorption 	 	 	 _ 	
,,„. Atomic Absorption. Furnace 	 - 	 _ 	 :. 	 „ 	
1 Atonic Absorption. Platform 	 _ 	 _.._ 	
Indoctivery Coucled Plasma ' 	 	 	
i iCP.Mais Soecuometry 	 , 	
„,.. Atonx: Absorption. Furnace 	 , 	 ; .
Atom* Absorption. Platform 	 _ 	 _ 	 _. „ 	 _ 	 ,
' Inductrvety Coupled Plasm* ' 	 	 	 _ . .
tCP'Mass Spectrometry 	 	 	 	 , . .
™» Atomic Absorption. Furnace 	 	
1 Atom* Absorption, Platform 	 	 	
. iCP-Masa Spectromeiry 	 _ 	 _ 	 _.. 	 	 „ 	
. 1 Distillation. Spectrophotometnc * 	 	 	 _ 	 	
• OistiHation. Automated. Soecvophotometnc 2 	 	
i Sefectwe Electrode ' 	 	 	
i Distillation. Amenable. Spectrophotometnc " 	 -...- 	 - 	 - 	

1
0003
4 Q OQOQ
0 0004
0001
0 0002
< 000002
0 0003
00003
0001
4 00006
0 005
0 0005
0001
4 00007
0 0003
002
0005
005
002

   ' Us«>j a 2X preconceitration step as noted in Method 200.7. Lower MDLs may be achieved when using a 
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             Federal Raster / Vol 57. No.  138 / Friday. |uly 17. 1992  /  Ralei md Regulation!
these corrections. However, they had  .
concerns on how the resulting
corrections would be used in the setting
of the PQLs. This issue is addressed
below in the PQL discussion.
  ICP-Mass Spectrometric Method (EPA
Method 200.8)—Several commenters had
concerns.with.thelisting.of EPA.Method  •
200.8 as an approved method because of
the following: (1) the absence of an
Intel-laboratory method validation study.
(2} the limited availability in
laboratories, and (3) the high acquisition
cost of the instrumentation. With
respect to the first point, the Agency
recognizes the usefulness of
interlaboratory performance data and
has recently completed an
interlaboratory method validation study
(Determination of Trace Elements in
Water by Inductively Coupled Plasma-
Mass Spectrometry: Collaborative Study
by J.E. Longbottom et aL. 1991). which
was made available for public comment
with the NOA. The resulting study data
indicate that laboratories using the  ICP-
MS method are quite capable of meeting
the  performance criteria (i.e.. MDL PQL
and acceptance limits) designated for
the metal contaminants in this rule. EPA
received no public comments on these
data.
   With respect to the second point
 regarding the limited availability of
 laboratories, the Agency believes that
 laboratory capability will expand with
 time. Although ICP-MS is not currently
 widely used. EPA expects a progressive
 evolution of the technique and an
 increase in its use analogous to the
 development and use of another mas*
 spectrometry technique, gas
 chromatography/mas* spectrometry
 (GC/MS). When GC/MS was first
 introduced, it was considered state-or-
 the-art and few labs had the expertise or
 instrumentation to employ, the
 technique. However, its use expanded
 quite rapidly and today there are very
  few laboratories that do not have the
  GC/MS instrumentation and employ this
  technique for routine analyses. The
  change in availability of GC/MS is
  attributed mostly to advantages and
  benefits for multi-analyte techniques, as
  discussed below. EPA believes this
  trend will also occur with the ICP-MS
  technique. Furthermore, this technique is
  only one of many being approved for use
  in the analyses of the metals in today's
  rule. Laboratories with the ICP-MS
  capability may.us,e it for analysis of thi
  metals in this rule, and those labs
  without it may use another method or
  consider acquiring ICP-MS
  instrumentation.
     In response to the third point
  regarding high acquisition costs of
instrumentation. EPA believes that
while ICP-MS represents a substantial
capital investment for labs, there are a
number of cost advantages associated
with having ICP-MS capability, i.e..
sensitivity, multiple metals analysis
capability and high volume sample
throughput. ICP.-MS is a. utable and...
precise technique capable of excellent
accuracy and very low detection limits,
thus providing a laboratory with the
option of performing multielement
analysis using one technique. Another
cost advantage  can be realized when
comparing the cost of running each
individual metal analysis on an atomic
absorption spectrophotorneter versus
the cost of simultaneous multiple metals
analyses on ICP-MS. Denpite the high
initial capital cost, ICP-MS capability is
cost-effective because of the speed of
analysis it provides, thus reducing
operational costs. EPA believes  that
these advantages will allow laboratories
using ICP-MS to expand their
capabilities and expertise and increase
their productivity.
   In conclusion. EPA has determined
that ICP-MS is  both technically and
economically feasible for routine
compliance monitoring and is
designating it as one of the approved
analytical methods for conducting
monitoring for the met a In in today's nil*.
   Digestion for Metals—-Commenters to
 the NOA expressed concerns about the
 clarity of EPA's requirements for the us«
 of the "total metals" technique and for
 digestion of drinking water samples
 prior to metals analysis. The
 commenters noted, first, that pp. 3-5 of
 Section (3030) of the seventeenth edition
 of the Standard Methods for the
 Examination of Water and Wastewater
 [USEPA, 1383), states:
   "Colorless, transparent samples
 (primarily drinking water) containing a
 turbidity of <1 NTU, no odor, and single
 phase may be analyzed directly by
 atomic absorption spectroscopy or
 inductively coupled  plasma
 spectroscopy for total metals without
 digestion*
   The commenter also noted that EPA's
 1983 "Method for Chemical Analysis of
 Water and Waste*" (MCAWW) on page
 Metals-5 states:
    "Drinking water samples containing
 suspended material and settleabla
 material should be prepared using the
 total recoverable procedure (4.1.4)
 * * * .". which included a digestion
 step.
    The commenters believe that in light
 of these statements, samples without
  suspended and settleable materials may
  not have to be digested The
  commenters stated that they recognize
that under certain circumstances, both
digested and undigested drinking water
samples should be compared to verify
that metals are being properly
recovered.
  EPA agrees that the requirements for
the use of the "total metals" technique
and for digestion of drinking water-   . •;.
samples may not be clear, which could
result in different interpretations by
different analysts. In addition to the
notes above, page Metals-'i of the
"Method for Chemical Analysis of
Water and Wastes" (MCAWW) states
that:
-  "While drinking waters free of
paniculate matter may be analyzed
directly, domestic and industrial wastes
require processing to solubilize
suspended material."
  While  digestion may be necessary for
turbid water samples. EPA does not
believe it is critical for non-turbid, clean
drinking water samples. The current
methodologies being cited for metal
analyses of drinking water samples are
applicable for samples of other matrices.
However. EPA agrees the guidance cited
above on whether to digest or not to
digest drinking water samples may not
be very clear. EPA believes that results
from analyses using the approved total
element  techniques, i.e.. graphite furnace
AA and ICP. can be reported as -total
metals" for non-turbid (<1  NTU)
samples that have been properly
preserved (cone HNO» to pH <2).
because under these circumstances the
"total metals" result is equal to the
"dissolved metals", since the
concentration of the "suspended metals"
would be negligible. However, samples
containing a turbidity greater than one
(>1 NTU) even though properly
preserved, require digestion using the
total recoverable technique as defined
in the approved methods, and can be
reported as  "total metals". Therefore, to
provide clarity for the "total metals"
 technique and to determine whether to
 digest or not to digest drinking water
 samples, EPA is amending the current
 requirement as footnoted in the tables of
 approved methodology. The revised
 footnotes will state:
    * Samples that contain less  than 1
 NTU (nephelometric turbidity unit) and
 which are properly preserved (cone
 HNO3 to pH <2) may be analyzed
 directly (without digestion) for total
 metals;  otherwise, digestion is required.
 Turbidity must be measured on the
 preserved samples just prior to th«
 initiation of metal analysis. Whtn
 digestion is required, the total
 recoverable technique as defined in the.
 method must be used.

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  31800
Federal  Register / Vol. 57. No.  138 / Friday. July 17. 1992 / Rules and Regulations
    10 For the gaseous hydride
  determination of Sb and Se, or for
  determination of Hg by the cold vapor
  technique, the proper digestion
" technique as defined in the method must
  be followed to ensure the element is in
  the proper chemical state for analyses.
    EPA believes that this revision will
  provide danty for "total metals"
  analysis and a means for determining
  whether digestion is required v\hen
  performing metals analyses in this rule.
  To provide consistency for all metals
  analyses for drinking water samples,
  EPA is also incorporating these
  footnotes, when applicable, by
  amending the tables of approved
  methodology in § 141.23(k)(4). which
  includes the metals in the January. 1991
  rule, and § 141.89{a). which includes   ,
  lead and copper.
   b. Ant'ons (cyanide ar.d sulfate]. (1).
 Cyanide. In the November 29.1991
 NOA. EPA addressed an issue ra-'sed in
 response to the July 1990 notice stating
 that although the proposed MCLG was
 based on "free" cyanide, the proposed
 analytical method's determine "total"
 cyanide. EPA concurred with
 commenters that it was appropriate to
 include methods that determined
 cyanide amenable to chlorination. or
 "free" cyanide. For this reason, the NOA
 proposed to add a methodology for
 amenable cyanide to the list of
 approved methods, and this notice
 finalizes the addition. The "total"
 cyanide methods are listed as well
 because they are adequate to screen
 samples for cyanide. If the "total"
cyanide levels are greater than the MCL
 then analysis for "free" cyanide should
be performed to determine whether
 there is an MCI exceedance. The "total"
cyanide analysis is still recommended
as an initial test because it is cheaper
than the amenable cyanide method.
There are several commenters to the
NOA who supported this action.
  Several commenters had concerns
with the approval of the titrimetric
method for cyanide because of its lack
of sensitivity (detection limit of 1 mg/1)
with respect to the PQL which was
proposed to be set at 0.2 mg/1. EPA
agrees with these commenters and has
rescinded the approval of this method
and deleted it from the list of approved
methods. The spectrophotometric
method has been added to the list of
approved methods for cyanide because
this method has adequate sensitivity.
This change was indicated in Table 6 of
the NOA. Comments received by EPA
supported these revisions.
  (2) Sulfate. A number of comments on
sulfate analytic methodi were received
Commenters objected to the absence of
the methylthymol blue method from the
                         list of approved methods and to the fact
                         that the "non-suppressed" column is not
                         stated as an acceptable option in
                         Method 300, an ion chroma tography
                         method, for sulfate analysis [USEPA.
                         1989dJ.
                           EPA agrees with the commenters that
                         the methylthymol blue.methodis.••-•••.
                         adequate. However, there are no data to
                         support the-use of the non-suppressed
                         column and the commenters submitted
                         no data to suppott it.
                           Commenters to the NOA objected to
                         the presence of the chloranilate method
                         for sulfate analysis and stated that the
                         chloranilate method has several
                         problems. They stated that the required
                         reagent (anhydrous chloranilate) is hard
                         to find and that only a single vendor
                         from England sells this form of the
                         reagent. Second, the analytical
                         equipment called for in the method  is no
                         longer available from the manufacturer.
                         In addition.  ASTM has dropped this
                         method from its most recent edition of
                         published methods and EMSL/CINN
                         (EPA) is considering  doing this as well.
                         EPA agrees with the commenters on all
                         these points.
                          However,  as discussed above. EPA is
                         deferring promulgation of a final
                         regulation for sulfate, and so is not
                         promulgating analytic methods for
                         sulfate in today's final rule.
                          c. Method detection limits and
                        practical quantitation levels. In the July
                         1990 notice, there were some
                         inconsistencies  and errors in the listed
                         method detection limits (MDLs) of the
                        cited methodologies for some of the
                        inorganic contaminants. Several
                        commenters  to the proposal and the
                        NOA expressed concerns with these
                        errors and inconsistencies. The Agency
                        addressed those concerns in the
                        November 29,1991 NOA and in this
                        final rule, respectively, by making the
                        appropriate corrections, as shown in the
                        NOA, and by clarifying how the MDLs
                        were used in setting the PQLs. as
                        discussed below.
                         EPA determines practical quantitation
                        levels (PQLs) for each substance for the
                        purpose of integrating analytical
                        chemistry data into regulation
                        development. This becomes particularly
                        important where MCLGs are zero or a
                        very low concentration, near or below
                        the detection limit. ThaPQL yields a
                        limit on measurement  and identifies
                        specific precision and accuracy
                        requirements  which EPA uses to
                        develop regulatory requirementi. At
                        such, PQLs are a regulatory device
                        rather than a standard that labs must
                        specifically demonstrate  they can meet.
                        The following is a discussion of how
                        EPA determined the PQLs for the
                        inorganic contaminants in today's rule.
    ' The proposed PQLs in the July 1990
   notice for cyanide and nickel were
   determined based upon MDLs and
   results from water pollution (WP)
   performance evaluation (PE) data as
   these data were available for
   concentrations near the MCLGs. There
   were-no PE data-available at the  u-'  f%r'
   proposed MCLG levels for antimony.
   beryllium and thallium. Therefore, the
   proposed PQLs for these contaminants
   were estimated from the respective
   MDLs by using "five or ten times the
  MDL" to set the PQL Only the proposed
  PQL for thallium was affected by the
  corrected MDLs discussed in the NOA.
    Several commenters  had concerns
  with EPA using the "five or ten times the
  MDL" to set the PQLs for antimony.
  beryllium and thallium. They asserted •
  that it is not feasible to measure these
  contaminants at these PQLs. As
  discussed in other FR notices. EPA
  prefers to set PQLs based on PE data or
  multi-laboratory collaborative study
  data: however, when such data are not
  available. EPA uses the generalized rule
  of "5 to 10 limes the MDL" to set the
  PQL Where data becomes available,
  EPA evaluates the data to verify the
  generalization or make the appropriate
  change(s) dictated by the data.
   EPA believes that the proposed PQLs
  for the inorganic contaminants are
  technologically and economically
  feasible and that in general the "5 to 10
  times the MDL" rule is a good estimate
 of laboratory practical quantitation
 capability for drinking water analyses.
 This assertion has now been
 corroborated by evaluations of Water
 Supply (WS) performance data for the
 five inorganic contaminants in today's
 rule.
   Several commenters to the NOA had
 concerns on how the WS performance
 data would be used. EPA has used the
 data in setting the PQLs in this rule as it
 has for most of the regulated inorganics,
 as discussed below.
   The final PQLs for all five inorganics
 were derived from data gathered in
 recent Water Supply (WS) PE studies,
 using the procedure described in 54 FR
 22100. May 22,1989. The  use of this
 procedure has been well  documented.
 The final acceptance limits and PQLs for
 antimony, beryllium and  thallium are
 based on EPA and State data from
 Water Supply PE studies  #024-027
 [USEPA. 1991dJ. These PE studies were
also evaluated to verify the earlier PE
data on which EPA based the proposed
acceptance limits and PQLs for cyanide
and nickel. The new study data, made
available for public comment in the
November 29,1991 NOA. indicated (1)
for antimony and thallium, for which

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             F«dwaT Ragbtar / Vol. S7, No. 1& /'Friday.  July it; 1992 / 'Rule* wuf Regulation*
two options were proposed, that their
PQLs be set at 0.006 mg/1 and 0.002 mg/
1. respectively (2) that the PQLs for
nickel and cyanide should be lowered
(the proposed PQLs for nickel and
cyanide were already at levels that were
at or below the proposed MCLGs) and
(3)  that the PQL for beryllium should
remain the same as proposed;-..
  The PQL procedure, described in the
aforementioned May 22.1989 notice.
generates acceptance ranges, i.e.. a
range of acceptable variation in the
analytical results compared to the
known or "true" value. The acceptance
limits for  the  inorganics in today's rule
were generated using the procedure
"used to derive PQLs and the laboratory
performance  data generated in Water
Supply Studies 24-27, which were
discussed in  the NOA. The PQLs  were
set at a concentration where it was
estimated that at least 75 percent of the
EPA and State labs are within the
specified  acceptance ranges. The final
acceptance limits (1) are tighter than
proposed for cyanide. (2) are bated on
the data rather than two standard
deviations for antimony, beryllium and
thallium and (3) remained the same for
nickel as proposed. The resulting PQLs
and acceptance limits are shown in
Table 12.

TABLE 12.—INORGANIC CONTAMMANT Ao
  CEPTANCE   LIMITS  AND  PRACTICAL
  O.UANTITATION LEVELS
Inorganic
contaminant
Antimony 	
Beryl bum 	
CyarwJe
Nickel
Thallium

MCL
(mg/1)
0006
0.004
02
0 1
0002

Acceptance
limits (plus
or tnnjt %
of the true
value)
30
15
25
15
30

POL
(mg/1)
0000
0.001
0 1
001
0002

preservation, containers and holding
times listed in Table 13 were proposed
for the inorganic contaminants in this
rule. One commenter on the NOA
mentioned that the addition of 0.6 gram
of ascorbic acid in the preservation of
cyanide is not applicable to all samples.
and that the  specific procedure in the .. •
methods should be followed to   '   '
determine the measure of ascorbic acid
required. EPA agrees with the
commenter and has amended the table
accordingly.
  No other comments were received on
these requirements. Therefore, the
Agency is promulgating these
requirements today, as listed.
  d. Inorganic chemical sample
preservation, container, and holding
times. The requirements for sample
         TABLE 13.—INORGANIC CONTAMINANT SAMPLE PRESERVATION, CONTAINER, AND HOLDING TIME REQUIREMENTS
Contarruneot
Antimony.— — __._ 	
Cyarw)6
Nickel
ThaHtum ._._ 	

Preservative '
Cone HNO> to pH < 2 	 ~ 	 --,..,-.. .-,., .,-,,,., ._. 	 __. 	 —._._...
Cone HNOi to pH <2 ... 	 	 	 	 	 	
Cool 4'C NaOH to pH >124 	 	 	 . _
Cone HNOi topH <2- 	 	 	 	 . 	
Go«eHNQi to p* <"!.-. ...... ,.„....-,...... 	 - 	 ~ 	

Container*
PorQ
PorG
PorQ
PorG
PorQ

Manmom hotdng time • •
emonttw.
6 month*.
14 days.

6 jikmBa.

    ' Samptes mat cannot be aod preserved at me tome o< collection became o4 sampbng limitations or transportation restrictions should be acidified with ratnc
 acid to a pH <2 upon recast n me laboratory. Following acidification, ffw sampM snoutd be held lor 16 noun betor* withdrawing an «*quot tor sample processing
 and/or anaiys*.
    " P «= plastic, hart or soft G - glaaa, hart or soft
    * In all cases, samples snook] be analyzed as soon after collection us posstte.
    * Ascot*: aod should onty be uSed in the presence at residue! cMome.
 3. Organic Analytical Methods
   A minimum of eight of the 17 methods
 included in today's rule are needed to
 measure the IB organic contaminants
 (Table 14). Eleven methods have been in
 use or promulgated in other rules; there
 were no significant comments on them.
 Four methods are single-analyte
 methods (i.e.. they measure only one
 analyte). Most systems will conduct
 compliance monitoring for contaminants
 to which they are vulnerable using one
 of the volatile organic chemical (VOC)
 methods and one to three other
 methods—Methods 515.1.525.1 and
 531.1—all of which may be used to
 measure the organic contaminants
 regulated in two previous rules
 promulgated on July 8.1987 [52 FR
 25690] and January 30,1991 [56 FR 3520].
  Some commenter* asked that when
EPA permits flexibility in method
selection by citing more than one
method for a contaminant, that the
detection limit practical quantitation
limit (PQL) and maximum contaminant
limit (MCL) be set differently for each
method; EPA disagrees. Although
method detection limits (MDLs) as
calculated by the procedure* in 40 CFR
130. appendix B may sometimes differ
for an analyte measured with different
methods, for regulatory purpose* EPA
must set a single PQL and MCL Sine*
laboratories can sometimes achieve
lower MDLs than thosa cited for •
specific listed method. EPA believes that
a laboratory which routinely achieves
the detection limits specified for a
contaminant (Table 14). should be
permitted to use that method for
compliance monitoring.
  EPA also received comments
recommending the use of alternate
analytical procedures. Because reliable
compliance data are necessary for
enforcement of the regulations. EPA
continues to cite only methodologies
included in EPA regulations, as
summarized in the guidance contained
in the laboratory certification manual.
However. EPA recognizes that
improvements in analytical technology
may occur frequently. Thus, the Agency
is developing a regulatory process to
expfriite the revision and updating of
older methods and the inclusion of new
methods for drinking water compliance
ana'y sis.

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   . > .      i     ..'-..
 31802        Federal RggUter  / Vol. 57. No. 138 / Friday. July 17. 1992 /  Rules and Regulations
       TABLE 14.—ANALYTICAL METHODS, DETECTION LIMITS. MDLs. PQLs. MCLs AND MCLGs FOR ORGANIC CHEMICALS
              EPA memod No,
                                                       Contaminant
                                                                                MDL
                                                                                          POL
    1 All concentrations a'e >n mg/1
    -Memoo 1613 [USEPA. 19901],
    • AN 500 Level Met-ocs fu'SEPA. !988e ana USEPA. 1990k]
                                                                                                    MCL
5021 5022,524 1,5242 . . ...
KZ 2 503 1. 524 2
S021 5022 52« 1 52*2 ,.
'6»3*
525 1 550, 5=0 « ...
SIS 525.)
5C6 525 I .
505 509. 525 *
505 508 525 t
505 525 I
505 507 5251
5*5 .
515 I ., . .... .
515'
S3« 1 ......
547
548 . ,„,..., 	 	 ,.
543 * . 	 	 	
Dtcnforometnane 	 	
	 1. 2. <»-TricniofoDenrene 	
1.1. 2-Tncmoroemane 	
2 3. 7. 8-TCDD lOioxm) 	 	
. ,. Benzo ia) pyr«ne 	 	 	 .
	 -.. Oi 12-ewiyinetyi) «ioit«..: 	 : 	
	 	 	 Di (2-einymexyi) pmtiaiate 	
Enonn 	 	
	 HexacmorooenzBnc 	 	 	
	 Hexacniorocyciopemaaiene 	
. . .. ... .... Simazine 	 . .
.... Daiapon 	
. 	 Dinoset) 	 	 .
	 Picloram 	
	 	 	 Oxamyl iVyoate) 	
. 	 	 Glyphosate 	 _
	 Enaotnail 	 	
	 	 Oiquat . 	 	 	
. 00002
. . 00003
00001
	 	 5 - 10 ' .
. . 0 00002.
. . . 0.0006 '
	 00006
000001
00001
00001
000007
0001
	 00002 :
	 0.0001 '
	 0002 i
	 0 006 :
	 : -6.009 •
	 00004 .
0005 :
0.005
0005 •
3 • 10 •
00002 :
0.006 '
0006
0001
0001
0001
00007 •
001 .
0002
0001
002
006
009
0004
0005
007
0005 '
3 • 10 •
00002 .
04
0006
0002
0001
005
0004
02 •
0007
05
02
07 •
0 1
002

0 07
0003


04

0002

Q OS
0004
02
0007
05
02
07
0 1
002
  a, Me&od-speafic comments. Some
comments were received on individual
chemicals--phthalates. adipates. 2.3.7.8-
TCDD(dio.xm). dalapon.
dichloromethane. endothall and
polynudear aromatic hydrocarbons
(PAHs)—and on certain methods being
approved for drinking water regulations
for !he first time—Methods 506. 547. 548.
549. 550. 550.1. 513 and 1613 [USEPA.
1988e and 1990k|.
  Several commenters believe that not
enough laboratories will be certified to
timely conduct compliance monitoring
analyses: EPA disagrees. These
comments were similar to those raised
and answered in  56 FR 3550 in the rule
promulgated on January 30.1991. EPA
also received a comment on the NOA
(56 FR 60949] about the effect of starting
the monitoring on January 1.1993 rather
than January 1.1996. EPA recognizes
that an earlier compliance monitoring
start-date accelerates the need for
certification. EPA also believes there is
some confusion about the criteria for
obtaining laboratory certification.
  EPA acknowledges that fewer
laboratories currently are proficient
with some of the  single-analyte methods
and the 2.3.7.8-TCDD Method 1613 than
with older pesticide and volatile organic
chemical methods. These same concerns
were raised by commenters when EPA
included  newer methods in the rule
promulgated January 30.1991. EPA again
expects systems to use vulnerability
assessments as a cost affective way to
characterize trends in their water
quality and thereby be eligible for
renewable monitoring waivers. For
these and other reasons stated in the
1991 rule  (56 FR 3550) EPA believes an
adequate number of laboratories will
have opportunity to obtain certification
 or^jrovisional certification for these
 contaminants in today's rule.
   Some commenters were concerned
 that high background contamination or
 interferences would make reliable
 detection and precise measurement of
 adipates. phthalates and
 dichloromethane difficult or impossible
 at the detection and MCL concentrations
 listed in the July 1990 notice. They
 believe that many false positives for
 dichloromethane. in particular, would
 occur due to ambient air conditions in
 the laboratory or sample collection site.
 All EPA methods detailed careful
 procedures that must be followed to.
 minimize or eliminate interferences or
 contamination that can occur in sample
 collection, shipment,  storage and
 analysis. In EPA's laboratory
 performance evaluation studies more
 than 75 percent of the laboratories have
 routinely and successfully analyzed
 samples with dichloromethane at
 concentrations near the practical
 quantification level of 0.005 mg/1. This
 affirms that laboratories appear to be
 taking  precautionary  steps outlined in
 the methods.
  Based on public comment and  further
 testing. EPA has  modified Method 508
 for the analysis of adipates and
phthalates. EPA switched from ternary
solvent mixture to the binary methytene
chloride and hexane solvent mixture.
which is used in a previously
promulgated EPA method! EPA Method
606. Using this modification, a very good
precision of ±6 percent was obtained in
replicate'measurements at
concentrations near the practical
quantification level.
  EPA  acknowledges that methods can
often be improved and the Agency
works to refine them and to adopt new
 analytic technology and techniques. For
 example. EPA's Environmental
 Monitoring Systems Laboratory in
 Cincinnati is working to change
 derivatization procedures that use' '
 diazomethane forthe measurement of
 several chemicals, including dalapon.
 Dalapon is now measured with Method
 515.1. EPA plans to include dalapon in
 the next version of Method 552. which
 will be named 552.1. Method 552.1
 replaces diazomethane with acidic
 methanol in the derivatization step, and
 liquid-liquid extraction is replaced by
 liquid-solid extraction. This should
 reduce interferences and improve the
 precision of the analysis.
   EPA also plans  to change the
 procedure (Method 548) for
 measurement of endothall. The new
 method would be  named Method 548.1.
 It would replace
 pentafluorophenylhydrazine with acidic
 methanol in the derivatization step, and
 liquid-solid extraction is used. The
 electron capture detector is replaced
 with a flame ionization detector in the
 new method. Data arid method write-ups
 were not available in time for these
 methods (552.1 and 546.1) to be included
 in today's rulemaking. However. EPA
 anticipates adopting these methods for
 compliance monitoring of dalapon and
 endothall as soon  as possible after they
 are released by the Environmental
 Monitoring Systems Laboratory.
  An early success is EPA Method 1613.
 which is a consolidated method for the
 measurement of 2,3,7.8-TCDD (dioxin) in
all matrices. It replaces Method 513.
 which had. been cited in the July 25,1990
proposal and as the method for
monitoring dioxin  as an unregulated
contaminant in the rule promulgated
January 30.1991 [56 FR 3592,

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                               / VoL  57. No. 13ft / Friday, July 17. 1992  / Rules and Regulation*
                                                                    31893
 1141.40(n)(ll)]. This rule promulgate!
 its use only for drinking water. Its use in
 other media will be promulgated as part
 of the appropriate regulations.
   EPA agrees with commenters who
 •fated that only one polynuclear
 aromatic hydrocarbon (PAH),
 benzo(a)pyrene. should be regulated at
 this time (see earlier discussion in':
 Section III-4). Three analytical methods
 were proposed in the July 1990 notice for
 the measurement of benzo(a)pyrene.
 Method 550 and 550.1 use high pressure
 liquid chromatography (HPLC). Method
 525 uses a gas chromatograph connected
 -to a mass spectrometer. No significant
, -comments were received on these
 methods. Methods 550 and 550.1 are
 included in today's rule for compliance
 analyses [USEPA. 1990k].           :
   Several commenters asked for more
 mass spectrometer methods to increase
 the number of analytes in an analysis
 and to decrease the probability of
 interferences that can cause false
 positives. EPA proposed multi-analyte
 mass spectrometric Method 525 in the
 July 25.1990 proposal. As discussed in
 an earlier Federal Register notice (58 FR
 30272, July'l. 1991), EPA improved the
 method, renumbered and adopted it as
 Method 525.1. Because Method 525.1
 supersedes Method 525. EPA is adopting
 525.1 for seven organic chemicals in
 today's rule.
   Method 525.1 has the potential to
 measure a large number of organic
 chemicals; the question is whether-the
 required sensitivity can be achieved. As
 always, laboratories using this method
 (and other methods) for compliance
  analysis must demonstrate an ability to
  achieve the detection limits specified in
 .Section 141.24 using the procedure
  described in 40 CFR part 136, appendix
 .B.
    Some commenters requested that EPA
  consolidate methods across all EPA
  programs and in all media. EPA realizes
  the difficulty laboratories may have in
  conducting certified analyses for the
  same organic chemical in several
  matrices over a wide range of
  concentrations using similar yet
  different EPA methods. Through EPA't
  Environmental Methods Management
  Council. EPA is working to consolidate
  methods, performance requirements and
  definitions of quantitation and
  detection. Regulatory, quality assurance,
 - enforcement and other issues make this
  a complicated task.
    b. Responses to comments specific to
 . Method 1613 for dioxin. EPA hat
  received comments related to the
   application of Method 1613 to the
   measurement of chlorinated dioxins end
   furans in drinking water. Some of these
   comments address a narrow range of
issues, primarily the Method Detection
Limit (MDL) and practical quantitation
limit (PQL). Others are very extensive in
that nearly every aspect of the technical
details in Method 1613 are addressed. In
organizing its response to the comments
submitted, the Agency has responded to
general issues first, then to comments
specific to the technical details of
Method 1613.
  Some comments on Method 1613
overall are incorporated into these
comment replies. Many commenters
were concerned about the performance
of Method 1613 on sample matrices
other than drinking water, particularly
on treated and untreated industrial
wastewaters. paper pulp, and sludge
from wastewater treatment processes.
EPA stated in the proposal of this rule
(55 FR 30426] that Method 1613 was
developed for-these matrices. In 1991
EPA proposed Method 1613 for analysis
of these matrices by industrial
discharges under the Clean Water Act
(proposed amendment to 40 CFR part
136 in 56 FR 5090. February 7.1991), and
solicited comments on that proposal. To
date.  EPA has not responded to the
comments received on that proposal.
Because EPA desires to move quickly on
today's drinking water rule, EPA is
responding to comments on Method 1613
related to application of the method to
drinking water prior to responding to
comments on the February 7.1991
proposal of Method 1613.
   General issues concerning Method
1613.  A commenter noted that Method
1613 has not been promulgated. EPA
agrees. As mentioned above. EPA
proposed Method 1613 under section
304(h) of the FWPCA at 40 CFR part 136
on February 7,1991, accepted comments
at that time, and has not promulgated
Method 1613 in part 138 as of today's
date. EPA has used data from its studies
of Method 1613 to support the practical
quantitation limit (PQL). the Method
Detection Limit (MDL), and other
 technical aspects of the regulation of
 dioxin in drinking water, in the same
 way  that EPA references other
 documents in support of its rules. The
 Agency is not required to use
 promulgated methods for reference
 purposes.  • •
   A commenter stated that EPA Office
 of Water Method 1613 and Office of
 Solid Waste SW-^646 Method 8290 are
 significantly different, contradicting
• recommendations to Congress in the
 report titled "Availability, Adequacy
 and Comparability of Testing
 Procedures for the Analysis of
 Pollutants Established Under section
 304{h) of the Federal Water Pollution
 Control Act" (USEPA, 1988f]. The
 commenter provided a block diagram
 showing differences in these two
 methods. EPA agrees that the two
 methods are different in exact technical
 detail, but the measurement principle of
 the two methods is the same. In
 developing testing methods for its
 regulatory programs, such methods
 evolve at different rates for different  .   .
 purposes. For example. Method 1613   '
 was originally developed primarily for
 use in treated and untreated effluents.
 but is applicable to pulps, sludges.
 drinking water and other solid and semi-
 solid matrices. Similarly. EPA Method
 6290 was developed for use primarily in
 solid and semi-solid matrices, but is
 applicable to analysis of water. EPA is
 in the process of consolidating methods
 for dioxin measurement in air. water.
 and solid waste, consistent with the
 recommendations in the report that the
'commenter references. However, such a
 merger cannot take precedence over
 EPA's development of methods to meet
 specific program heeds and for
 regulatory programs with Congressional
 deadlines and court-ordered timetables.
   A commenter stated that, although
 EPA used Method 1613A for analysis of
 more than 500 samples, there have been
 many versions of this method and the
 data produced using these versions were
 inaccurate. EPA acknowledges that
 some data produced with early versions
 of Method 1613 may have been less
 accurate than data produced with more
 recent versions. Much of these earlier
 data were developed using complex
 matrices, such as industrial effluents,
 and were generated as the method was
 being developed. The method and MDL
 proposed in the November 1991 notice,
 and being finalized here, are based not
 on these early data but on later data
 generated using reagent water, which is
 a matrix more similar to drinking water.
 The accuracy of analytic methods
 usually improves with experience in
 using the method. However, the fact that
 data become more accurate as a
 function of time does not mean that
 earlier data are necessarily unsuitable
 for their intended purpose. The Agency
 is careful to consider in its rulemaking
 the effects of the variability of the
 analytical data. For example, in this
 rulemaking. data variability is
 accounted for in the determination of
 the MDL and is considered in setting
 the PQL.
   A commenter noted that Method 181J
 calls for instrument calibration to be
 verified at a high level, but that
 calibration should be verified instead at
 the minimum level because of
 uncertainties at that level. EPA
 disagrees that calibration should be
 verified at the minimum level. In method

-------
31804       Federal Register / Vol.  57. No. 138 /  Friday.  July  17. 1992 / Rules  and Regulations
1613, calibration it verified at the mid-
point of the analytical range. This
verification is common and accepted
practice for analytical methods (see e.g..
the methods in 40 CFR 136. appendix A).
The generally accepted practice
followed by EPA is to verify calibration
in a region where  error is a constant.
proportion, of the level being measured.
This may not be the case if calibration
were done at the minimum level.
  A commenter stated that the MDL
tes's for Method 1613 use reagent water
for tests of initial precision and recovery
(1PR) and on-going precision and
recovery (OPR). and that this practice is
inappropriate for methods that must rely
on extensive cleanup. Reagent water is
water in which the analyte(s) of interest
and interfering compounds are not
detected by the method being used. EPA
disagrees that reagent water is
inappropriate for the IPR. OPR. and
other tests. EPA believes that in the case
of dioxin in drinking water, reagent
water and dnnking water are nearly
equivalent matrices, in that the
concentrations of potentially interfering
compounds in drinking-water are
extremely low.
  A commenter stated that allowing the
analyst the flexibility to modify the
method may adversely affect method
performance on real world samples, and
cited as examples that the performance
test solution used  to evaluate the
particular columns in Method 1613 will
not work with other columns, and that
reducing the solvent volumes to elute
the dioxm from the AX-21 cleanup
column would prevent analysts from
meeting the detection limits specified in
the method. EPA disagrees. In      	
developing and promulgating the 40 CFR
part 136. appendix A methods. EPA has  .
received comments in the past similar to
this one that the methods should allow
no flexibility in procedures [49 FR
432461. EPA also received comments
that there should be great leeway to
modify the methods [49 FR 43245). EPA'i
general response to those comments and
to this comment is that flexibility is
permitted only in discretionary elements
of the test procedures, and that the dad
generated must meet all  stated
performance criteria.
  For the specific examples that the
commenter cited. EPA believes that the
requirement for an alternate gas
chromatographic column to meet not
only the specifications for the
performance test solution but also to
meet the relative retention time criteria
in Method 1613 effectively preclude*
any column with Inferior performance,
and that reducing the solvent volumes
used with the AX-21 column to the point
where native dioxin becomes non-
detectable would probably cause the
recovery of the labeled compounds to
fall below the recovery specifications in
the Method: therefore, this would not be
allowed.
  EPA notes that the objective of
permitting flexibility»in certain  ••'
discretionary parts of its "methods is to
allow for improvements in technology
while requiring all performance
specifications in the method to be met.
  A ccmmenter included with its
comments approximately 40 pages of
suggested technical modifications of
Method 1613 to improve the reliability of
the Method. EPA appreciates these
suggestions. This commenter has
participated in EPA's validation studies.
has conducted validation studies of its
own. has scrutinized the details of
Method 1613 and other EPA methods.
and has provided many valuable
suggestions for  improvements to these
methods. EPA has considered all of
these suggestions, as well as the
suggestions of others, in its continuing
evolution and upgrading of analytical
methods, and shall continue to work
with all interested parties to assure that
these methods are as state-of-the-art as
possible. Many  of the suggestions relate
to analyses of more complex non-
drinking water matrices and are not
relative to analysis of drinking water
samples.
  1613  Inter-laboratory study. A
commenter said that EPA had not
completed its inter-laboratory study of
Method 1613 at  time of proposal of the
drinking water regulation for dioxin, and
that EPA is premature in proposing
Method 1613 without validating it first.
EPA has relied only on the MDL studies
on Method 1613 in determining the MDL
and the PQL Inter-laboratory validation
studies are on-going and EPA will make
them public when complete. However,
EPA is not required by statute or policy
to use inter-laboratory data to establish
MDLa or PQLs.
  Two commenters stated that EPA's
inter-laboratory study used extracts of
samples but  not real-world sample*.
Both commenters are correct However.
this rule relies on an MDL study as the
basis for the PQL. and not the inter-
laboratory studies. Therefore, this ii not
a relevant issue for this  rule. EPA used
extracts of real-world sample* because
the shipment of large volume* of dioxin-
contatning water both intra- and inter-
nationally was deemed to be too great a
risk to human health and th«
environment and because of the
difficulty in producing a homogeneous
mixtur* of dioxins In such large weter
volume*. EPA underttand* the
 commenters' argument and concerns
 that performing an inter-laboratory
 study on extracts of water rather than
 water itself could possibly result in less
 bias and greater precision than if water
 had been used, but EPA believes that
 the risk of using raw waste water
 samples'-was-unacceptable: EPA'has
 recently collected and received a large
 volume of data on application of Method
 1613 to paper industry wastewater and
 believes that the matrix effects
 associated with extraction of dioxin
 from water are fairly well quantified at
 this point. EPA believes that its
 international inter-laboratory validation
 study will be valuable in assessing
 method and laboratory performance.
 even though the study will not be
 conducted on raw wastewater.
 However, the complex matrix effects
 these data are intended to identify and
 help resolve are not relevant to drinking
 water samples.
   SDS extraction. A commenter stated
 that the Soxhlet/Dean-Stark (SDS)
 extraction procedure for solids  has only
 been tested to a limited extent on one
 municipal sludge.- The commenter was
 correct at the time of this comment in
 that EPA had performed limited testing
 of the SDS extraction procedure on a
 limited number of samples. Since that
 time, EPA and others have extracted
 many sample* using the SDS technique.
 and although some data show that some
 of the higher isomer* and congener* of
 dioxin may not be extracted as
 efficiently as other extraction
 techniques. EPA has not confirmed the*e
 results. However, SDS extraction is not
 a  method that would  be used on
 drinking water samples, and so this
 comment is not relevant to the present
 rulemaking.
   A commenter noted that use of liquid-
 solid extraction using 3M"» Empon Disk
 is approved by EPA for Method 525.1,
 and ia included in dioxin Method 513.
 The commenter suggested that EPA
 include the option of using the Empore
 Disk in Method 1613.  EPA i* currently
 evaluating the Empore disk a* «n
 extraction device for  cqueou* sample*
.in Method 1613. EPA'* Environmental
 Monitoring Systems Laboratory in
 Cincinnati. Ohio (EMSL-Ci) has
 performed extensive testing of liquid-
 solid extraction devices. EPA will
.continue to study the  Empore disk and
 similar device* because of their
 potential for reducing solvent use in the
 laboratory, and will incorporate such
 devices into Method 1613 and other EPA
 methodu if the performance of the*e
 device* 1* demonstrated to be
 equivalent to extraction device*
 presently In these method*. Nationwide

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              Fadarii Rggiftef / Vol. 57. No. 13d / Friday. July 17. 1992 / Rules and Regulation       31005
 application for an alternate test
 procedure may be made under 40 CFR
 138.5.
   Labeled compound recovery. A
 commenter stated that recovery of
 labeled compounds in Method 1613 do
 not adequately correct for incomplete
 recovery of the native analytes.because
 it is nearly impossible to spike the
 labeled compound into the sample in
 such a fashion that it distributes itself
 identically to the native anaiyte. EPA
 has chosen the isotope dilution
 technique for quantification because it  is
 the most precise analytic technique
 currently available to measure dioxin.
• EPA is aware that in some instances the
 labeled compounds are not distributed
 identically to the native analytes. but
 believes that the advantages of the
 isotope dilution technique far outweigh
 any limited imprecision and reduced
 accuracy that may occur when external
 standard quantitation techniques are
 used. Nearly all analytical methods for
 dioxin employ isotope dilution to
 provide the highest accuracy and
 greatest precision.
    Method Detection Limit (MDL) and
 minimum level. A com.menter stated
  that Method  Detection Limits (MDL's)  of
  5 and 10 ppq for Methods 1613 and 513.
  respectively, have not been
  demonstrated and that it is not possible
  for even the best laboratories to attain
  the MDL developed by EPA. EPA
  disagrees. EPA has now demonstrated
  that the MDL = 5 ppq using Method
  1613, as described in the NOA.
    A commenter stated that the proposed
  standard for dioxin is based upon
  detection limits associated with .
  outmoded analytical methods that are
  thousands of times less sensitive than
  the most advanced methods available.
  that methods developed by Christoffer
 ' Rappe, University of Umea, Sweden are
  capable  of detecting TCDD at 0.001-
  0.020 ppq in drinking water, and that •
  Canadian methods achieve MDL's of 2
  ppq in pulp mill effluents and could be
   extended to achieve 0.2 ppq in drinking
  .water. EPA  is aware that it is possible to
   achieve lower detection limits by
   revising the dioxin methods to use
   sample volumes 10 to 1,000 times (or
   more) larger than the existing methods.
   At present,  most dioxin methods employ
   a one liter sample. This sample is
   shipped from field locations to
   laboratories that have HRGC/HRMS
   instruments. Samples will need to
 '  continue to be shipped from remote
 V locations to laboratories. Most sample
   shipments are by overnight courier 10
   that the samples can be maintained
   refrigerated froth the time of collection
   until extraction. Shipping 10 to 1.000
liters presents unique logistics problems
and is prohibitively costly (a 1.000 liter
sample weighs approximately 2.500 Ibs..
and costs $1.50/lb. to ship for a total of
$4.500 per sample). Also, while large
volume samples might theoretically
result in a lower MDL, increased
interferences are likely.to result EPA is.
aware of no data demonstrating that
lower MDLs may be achievable. An
alternative  would be to collect the
samples on a liquid-solid extraction
device at the  remote location and ship
the device to  the laboratory. However.
EPA has not developed or validated this
sampling means at this time. EPA is
aware of the  methods proposed for
regulatory use in Canada, and believes
that the improvements in sensitivity
suggested by the commenter are simply
the result of differences in terminology
and reporting practices. The Canadian
methods use  the term "MDL" to mean
the sample-specific detection limit that
is calculated solely on the basis of
signal-to-noise measurements. In
contrast. EPA uses the term MDL to
refer to the statistically determined
value that results from replicate
measurements, as described in 40 CFR
part 136. appendix B. EPA will continue
to study devices and procedures for
lowering the detection limit to levels
commensurate with the Agency's
measurement and regulatory needs.
   1613  Method Detection  Limit (MDL}
study. A commenter utated  that the 5
 ppq MDL in Method 1613 was calculated
 from a single-shot experiment that does
 not represent a real work estimate of the
 MDL It alleges that a real world
 estimate of the MDL is at least 10 ppq
 based on the 104 mill study and an
 estimate by Georgia-Pacific. EPA agrees
 that the MDL in Method 1613 was
 obtained by a single use of the MDL
 procedure [40 CFR part 136. appendix BJ.
 As described in the proposal of Method
 1613. the MDL procedure was followed
 as prescribed, with a result of 5 ppq.
 EPA has reviewed the data submitted by
 the contract laboratory that performed
 the MDL procedure and believes that the
 tests were performed properly and that
 the 5 ppq MDL is valid.  EPA believes
 that if the MDL procedure were
 performed in other qualified
 laboratories, similar results would be
 obtained using Method  1613. although
 some laboratories might obtain slightly
 higher or slightly 'lower results.
 However, the MDL is by definition a
 single laboratory single operator
 concept EPA is unaware of any samples
 in the 104 Mill study that were analyzed
  at least seven time*, or that conformed
  to other requirements of the procedure
  for determining the MDL The
commenter provided no specific data for
analysis. Moreover, the 104 Mill study
analyses concern pulp, sludge and
industrial wastewater matrices and so
the MDL derived in that study is not
necessarily the lowest that could be
obtained in samples that more closely
resemble drinking-w.ater,matrices.:••..:'• •<:
  Two commenters daim that the MDL'
study cited was conducted with'reagent
water and. therefore, the MDL study is
not relevant. As EPA stated in its
response above to the use of reagent
water for initial and on-going precision
and recovery and other quality control
tests. EPA believes that in the case of
dioxin in drinking water, reagent water
and drinking water are nearly
equivalent matrices, in that the
concentrations of potentially interfering
compounds in drinking water are
extremely low.
  A commenter said,that no data are
presented in the Federal Register notice
[56 FR 5090] other than for reagent
water. Therefore, the proposed minimum
levels for solid matrices are
insupportable. For the purpose of the.
regulation of dioxin in drinking water.
data on matrices other than on reagent
water or drinking  water are
unnecessary.
  A commenter said that the MDL
experiment is inappropriate due to the
high spike levels chosen for the study.
that the variability increases as the
concentration levels approach the MDL
and that the only way to truly determine
the MDL is to perform the experiment at
the exact  level of the MDL. EPA notes
that the 25 ppq level was chosen as
described in EPA's proposal of Method
1613  [56 FR 5095). As stated earlier. EPA
believes that its contract laboratory
followed the MDL procedure correctly.
 including the use of 25 ppq as the
 spiking level. EPA agrees that the
 variability increases as the
 concentration levels approach the MDL.
 However, one of the tenets of the
 concept of the MDL is that the
 relationship between the level and the
 standard  deviation of the measurement
 becomes approximately constant in the
 region of the MDL and the spiking level
 is not critical in this region. In addition.
 EPA believes that spiking at too high a
. level will tend to overestimate the MDL
 rather than underestimate it. EPA is also
 in the process of contracting for
 additional MDL studies in a variety of
 matrices and at other spiking levels
 appropriate to the matrices. These data
 will  be made available at a later date.
   Two commenters stated that it is well
' known that a break in the calibration
 curve occura at approximately 5 ppq.
 Consequently  extrapolation from 25 or

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  31806       Fscteral Ragbter / Vol. 57. No.  138 / Friday. July 17^992 / Rules and Regulation*
  12 ppq to 5 ppq is not technically valid.
  Extrapolation must be made at or below
  the break point. One of the commenters
  stated further that extrapolation of the
  instrument calibration far beyond
  demonstrated performance is not sound
  science and provided a graph showing
  relative standard deviations a function
  of corresponding effluent.concentration-
  for native dioxin m calibration
  standards. EPA agrees that calibration
  error increases as concentration levels
  approach the MDL but believes that the
  measurement of the MDL in Method
  i613 was made  in a valid region of the
  calibration curve and was made
  according to the MDL procedure, as
  detailed in the proposal of Method 1613
  |56 FR 5035] and the support documents
  for the NOA. EPA has reviewed the
 graph provided by the commenter and
 boheves that the graoh supports the
 vji:<:ity of an MDL of 5 ppq. The graph
 shows data points at  equivalent
 concentrations of approximately 3. 5.12.
 100.1.000 and 5.000 ppq. associated with
 relative standard deviations of
 approximately 16. 8. T. 5. 2 and 1
 percent, respectively. Calculating the
 relame standard deviation (RSD) of
 these vaLes results in standard
 deviations of 0 48.0.40. 0.84. 5. 20. and
 100 ppg.  respectively, for the
 concentrations. Assuming that the RSD's
 are the result of three replicate
 determinations, the Student's t
 multiplier used in the  MDL procedure is
 6.97. resulting in MDL values of 3.4. 2.8,
 5,9. 35,140. and 700 ppq. (If more than
 three replicates were used, the MDL
 values would be lower). These data
 clearly show that in the region of the
 MDL (2-10 ppq). the MDL is
 approximately constant, but rises
 rapidly as the spike level increases.
 Thus, the use of a high spike level would
 tend to overstate the MDL. the opposite
 of what is argued by the commenters.
 Further, the data provided clearly show
 that measurement can be made in the
 range of 5 ppq because data were
 reported in (his range.
  Two commenters stated that dioxin
 was not detected in one of seven
 replicates in EPA's test of the MDL for
 Method 1613. EPA believes that in EPA'g
 studies of the MDL for Method 1613.
 EPA's contract laboratory performed the
 study improperly in its first attempt. In
 this attempt, the laboratory spiked the
native analytes into the blank that was
a part of the quality control associated
with the MDL test. Also, aa pointed but
by the commentei*, the laboratory failed
to detect dioxin in one of the seven
replicates. EPA rejected the data from
this MDL study, and had the laboratory
determine the MDL under the controlled
  conditions that EPA requires. The MDL
  of 5 ppq that EPA state* for Method 1613
  is the result of the properly conducted
  study. EPA did not formally release the
  results of the improperly conducted
  study, but has made all results of all
  studies available to all interested
  parties.
 •, •' MDL/POL-issues^''Acommenler said' "
  that the lowest level that can be
  measured is the.PQL. EPA disagrees.
  EPA has demonstrated that
  measurements can be made as low as
  the MDL, but has defined the concept of
  the PQL as the lowest Jevel that can be
 reliably achieved within specified limits
 of precision and accuracy during routine
 laboratory operating conditions (50 FR
 46902J. Thus, the PQL provides an
 allowance for the degree of
 measurement precision and accuracy
 that EPA estimates can be achieved
 across laboratories. If EPA desires a
 level of measurement precision and
 accuracy that is high, the PQL is set
 slightly higher (on the order of 10 times
 the MDL); whereas if the Agency desires
 a slightly lesser level of measurement
 precision and accuracy (in exchange for
 reduced health risks). EPA will set the
 PQL level somewhat lower (on the order
 of 5 times the MDL). but  EPA believes
 that measurements can be made in the
 range between the PQL and MDL.
   A commenter stated that finalization
 of the PQL should await  completion of
 an appropriately designed inter-
 laboratory study because the PQL is
 intended to reflect performance of
 multiple laboratories. The commenter
 also noted that the preferred method of
 determining the PQL would be to utilize
 performance evaluation data from as
 many labs as possible. EPA believes
 that inter-laboratory studies, whether
 method validation or performance
 evaluation, are useful in establishing the
 PQL but also believes that a multiplier
 of 5 -10 times me MDL is an effective-
 way to establish the PQL. In estimating
 the PQL, EPA takes into consideration
 all data available, including single
 laboratory, multi-laboratory,
 performance evaluation, and other data,
 as well as regulatory needs to protect
 human health and the environment. In
 the regulation of dioxin in drinking
 water. EPA has reviewed the data from
 its study of Method 1613, as well as data
 submitted by c«mmenter>. EPA has
 established the PQL for this rule after a
 review of technical data from method
 studies and from health risk
considerations.
  A commenter said that decreasing the
PQL from 50 ppq to 30 ppq represents «
very slight decrease in the level of risk
that does not justify the drastic increase
   in the level of uncertainty that would
   occur. EPA disagree, that there i« a
   drastic increase in the level of
   uncertainty between 50 and 30 ppq. As
   the data submitted by the commenter
   demonstrate, the uncertainty
   attributable to calibration increases
   from approximately  six percent Jo.    4
   approximately seven percent when the
   level decreases from the equivalent of 50
   to 30 ppq.
    A commenter stated that it is a
  longstanding practice within the
  scientific community to use a 3-fold
  multiplier in establishing the limit of
  quantitation. The American Chemical
  Society (ACS) uses the concepts of the
  Limit of Detection (LOD) and Limit of
  Quantitation (LOQ) in discussions of the
  lower limits of analytical'measurements.
  The LOD is approximately equivalent to
  EPA's MDL and the LOQ is
  approximately 3.3 times the MDL As
  EPA has stated in previous discussions
  of the PQL (50 FR 46902). the MDL and
  LOQ are single laboratory concepts.
  whereas the PQL is the lowest level that
  can be reliably achieved within
  specified limits of precision and
  accuracy during routine laboratory
  operating conditions.  EPA uses a
  multiplier of 5 to 10 times the MDL as
  well as other factors to establish the
  PQL EPA is presently in the process of
  reviewing its approach to establishing
  the limits of analytic chemistry for
  drinking water samples and the use of
  this information in setting drinking
 water standards. EPA may propose
 revisions to its general approach in a
 later Federal Register  notice. The ACS
 concepts are'among those that will be
 considered in this process. EPA will
 review its MCLs at that time to
 determine whether revisions are
 appropriate.
   A commenter stated that the PQL
 should be set at 10 times the MDL since
 the carcinogenic risks  do not justify less
 precision in dioxin measurement. As
 EPA has noted in response to other
 comments. EPA hat set the PQL at
 approximately five times the MDL based
 on technical and health risk
 considerations. The PQL is a regulatory
 tool that may include consideration of
 health risk. EPA also reiterates that the
 precision of the dioxin measurement is
 not significantly degraded between 50
 and 30 ppq.
   c. Detection and quantitation levels:
laboratory performance criteria. Many
comments were received on EPA'i
procedures for determining MDL§ and
PQLs. Calculation of method detection
limits (MDLi) by procedures Ml forth at
40 CFR Part 138 Append?*. B i«
understood and generally accepted by   i

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ST. No. 138  /
                                                            July 17. 19«  / Rule* «nd Regri«tk»n»
the laboratory community. A few
cotnmenten wrote that since Mine
MDLs cited in EPA methods are a one
time determination by one analyst the
results may not generally be achievable
by the number of laboratories needed to
handle compliance monitoring on a
routine basis. EPA believes that
laboratory performance improves'** an-r
analysis progresses from being novel to
routine. The purpose of the PQL concept
is to allow for this inter-laboratory
variability and ensure that the majority
of good laboratories can adequately
measure contaminants, EPA has also
provided relief for most contaminants in
today's rule by permitting performance
evaluation samples to be judged by the
results of the group of laboratories
participating in each study rather than
on an absolute scale (Le. the pass
criteria are two standard deviations
from  the average result rather than
within a fixed ±:percentage of the
spiked concentration).
   The selection of practical'quantitation
levels (PQLs) has been discussed at 55
FR 30370 and references therein. EPA
received comments on PQLs identical or
similar to those received and responded
to in  earlier rules [55 FR 30370, and 56
FR 3547-3552 and 30269-30271]. Some
commenters on the July 1990 proposal
wrote that some PQLs were too low for
most laboratories to quantify a
 contaminant .with acceptable precision
 because EPA relied too much on
 performance by the "best" laboratories
 in setting the PQLs. Some commenters
objected to the PQL for dioxin that WM
proposed at five times the method
detection limit They suggested all PQLs
be ten or more time* the MDL even if
this required that a maximum
contaminant level (MCL) be increased;
EPA disagrees. EPA recognizes that use
of a five-fold multiplier, rather than ten-
fold, may result in some loss of precision
and accuracy in performing analyses.
However. EPA believes it is sometimes
appropriate te- accept somewhat greater
imprecision and. inaccuracy when
necessary to achieve health risks within
EPA'? target risk range. EPA makes such
judgments on a case-by-case basis.
  Other commenten stated that some
PQLs were too high, especially for
contaminants with xero or very low
maximum contaminant level goals.
These commenters nuggested that PQLs
and MCLs could be lowered
significantly to reduce risk, thereby
allowing only  the best laboratories to
perform compliance analysis. However.
EPA believes this is impractical, due to
 the large number of compliance samples
 that are required to be analyzed by
 these rules.
   In response to this interest in
 detection and quantitation levels. EPA.
 the American  Chemical Society (ACS)
 and the American Society for Testing
 and Materials (ASTM) are working on
 standard definition:) of analytical
 detection and quantitation levels for
 chemical analyses in any matrix The
 definitions, if adopted by EPA. would be
 only a part of the process  used to
 determine the feasibility of measuring a
 contaminant with acceptable precision
 at the MCL The Agency is also
 developing criteria to define what data
 should be collected to set
 interiaboratory performance standards.
  EPA has determined, however, that it
 is appropriate to set PQLs for today's,.
 contaminants using the procedures  •
.discussed in the proposal (55 FR 30370
 and references therein) rather than
 waiting for the results of the new
 definitions. The maximum contaminant
 level goal (MCLG) for several of the
 organic chemicals in today's rule is
 significantly greater than the MDL listed
 for each contaminant in the EPA
 methods. This means setting MCLs
 equal to MCLG does not pose the  same
 problem as when  reliable detection and
 quantification is desirable near or below
 MDLs.
  For sixteen regulated organic
 chemicals in today's rule, the PQLs are
 based on laboratory performance data.
 As discussed earlier, considerable
 variation in interiaboratory performance
 was observed. For this reason, the PQLs
 for benzo(a)pyrene and 2. 3,7.8-TCDD
 are respectively estimated at ten times
 and five times the method detection
 limit (as defined at 40 CFR part 136.
 appendix B). Table 15 lists MCLs, PQLs
 and laboratory acceptance limits  for
 each organic contaminant. The ranges of
 concentrations included in EPA's
 laboratory performance samples are
 also listed
          TABLE 15.—MCLs, PQLs AND ACCEPTANCE LIMITS DirrERMtNeo FROM LABORATORY PERFOPMANCS STUDIES
Contvnrw*





O (2-*ttryfrie*yn a<*c*tft 	 	 	



EfxJrm .— ....-— 	






2.3.7.8-TCOO (Dwxm) 	 	 	
MCLoW
0.07
0.005
0.0002
0.2
0.005
0.4
0.008
0.007
0.02
0.1
0.002
0.7
0.001
0.05
a*
o.s
O.CO4
3X1I3-*
POL
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 31806       Federal Regutar /  Vol. 57.  No. 138  /  Friday. July 17. 1992 / Rules  and Regulation*
 cotnmenters that the performance by the
 current pool of laboratories does not
 warrant setting pass/fail criteria within
 fixed plus or minus percentage limits of
 the true concentration and acceptance
 limits for the other organic contaminants
 in today's rule remain at :r2 standard
 deviations. EPA disagrees with the
 comment tha: regulation be delayed.
 unul fixed acceptance ranges can be
 determined by interlaboratory
 performance. EPA believes performance
 will improve as laboratories routinely
 use a method to maintain certification
 for compliance monitoring analyses. The
 new methods are based on the same
 basic analytic techniques as many
 existing methods (such as GC. GC-MS,
 HPLC). EPA's experience in applying
 these techniques to other analytes has
 been that laboratory proficiency
 improves as laboratories become more
 experienced with the basic technique
 and specific individual methods.
   Although the data  are insufficient to
 change the proposed certification
 acceptance limits, they are sufficient to
 examine the relationship between study-
 generated PQLs and PQLs calculated by
 multiplying MDLs by a factor. In today's
 rule. EPA has set PQLs for 16 organic
 contaminants after considering an
 analysis of the performance from EPA-
 sponsored laboratory studies and MDL
 data. In most cases the PQLs are  ten
 times the MDL. For four contaminants.
 the PE data were adequate for
 establishing the PQLs. For the
 remainder. PQLs were established on
 the generalization of 10 times the  MDL.
 For many of these contaminants, a
 limited number of laboratories
 participated in the PE studies, and EPA
 therefore believes these data do not
 adequately represent likely performance
 over time. For other cases, while there
 were a considerable number of
 laboratories participating, the
 regression-derived acceptance limits
 were broad (> =50%). and the PQL was
 based on 10 times the MDL,  with
 acceptance limits set  at ±2 standard
 deviations, to allow for improvement in
 the future. EPA found that federal and
 Stale laboratories, which were more
 experienced with the  methods
 performed better. EPA therefore
 believes the other laboratories'
 performance will improve over time and
 use of 10 times the MDL to set the PQL
 is appropriate.
  For dioxin (PQL=5 MDL) and
 benzo(a]pyrene (PQL=10 MDL). PQLs   -
 could not be derived from an analysis of
 the limited laboratory performance
 database. The commenter correctly
notes that in most studies.
benzo(a)pyrene was not tested near the
  final maximum contaminant level of
  0.0002 mg/1. However, in the November
  29.1991 notice and in today's rule. EPA
  discusses a two-laboratory study of this
  contaminant. The precision obtained in
  samples spiked at 0.0002 mg/1 was
  excellent—±6 percent or better. A
  similar study,  which is discussed in
  today's rule..fordioxin using Method.-.-.
  1613 was conducted with good results.
  Thus, the PQL for dioxin and
  benzo(a)pyrene-are today specified
  respectively as five and ten times the
  MDL.
   The final PQLs for di(2-
  ethylhexyljadipate and di(2-
  ethylhexyl)phthalate are set at ten times
  the MDL. This  is consistent with EPA's
  general guidelines that calculated PQLs
  be equal to five to ten  times the MDL.
  The commenter refers  to the relatively
  poor performance in some of EPA's cited
  studies. However, in the November 29,
  1991 notice and in today's rule. EPA
  discusses an improvement in the
 Method 506 eluant mixture, which has
 been tested in samples spiked near the
 final maximum contaminant levels. EPA
 believes these data warrant setting a
 PQL at ten times  the MDL.
   EPA notes that PQLs that are'based
 on an evaluation  of the concentration at
 which about 75 percent of the
 laboratories participating in a study can
 successfully analyze a  sample use a
 criterion that is more stringent than
 setting a pass criterion of ±2 std. dev.
 Using this approach, the final PQLs for
 volatile organic chemicals are very close
 to ten times the MDL. This is consistent
 with the performance observed with
 other regulated volatile organic
 chemicals, all of which can be measured
 in the.same sample by an identical
 analytical procedure. Since analyses for
 dioxin. pesticides and other organic
 chemicals in today's rule use several
 different analytical techniques. EPA
 expected laboratory performance would
 be less homogeneous than for the VOC
 chemicals, which  used the now-routine
 purge and trap method. Use  of study-
 dependent laboratory criteria is
 consistent with  the requirement to
 achieve the lowest feasible MCL
  EPA disagrees that performance
 sample data need  to be  normally
 distributed in order to proceed with a
 determination of the suitability of a
 method for compliance measurements. It
 is not practical or  necessary to
 benchmark interlaboratory performance
 on anything but  a standard matrix. Each
analytical method notes if and how the
analyst should check a compliance
sample or laboratory reagents for
possible interferences. As discussed in
today's rule,  the available data indicate
   that laboratories have done so even
   with potentially difficult analytes such
   as dichloromethane.
    EPA agrees with the comment that
   when analytical variability poses a
   problem, the system should have the
   opportunity to use multiple samples and
   average the results. EPA's monitoring   •
  requirements-already proVide this'relief:
  The requirements permit confirmation of
  sample results, and the elimination  (with
  State concurrence) of spurious
  analytical results. And more than one
  confirmation sample  may be taken.  •
  provided the State concurs.
    EPA notes that for  most of the
  analytes presented in the table with
  relatively high confidence intervals, the
  PQLs and MDLs are significantly less
  than the final MCLGs and MCLs. so
  imprecision of the analysis is not as
  likely to lead to resource-wasting false
  positives.
    The  PQLs for most  of the
  contaminants are identical to the PQLs
  proposed on July 25,1990. The PQL for 2.
  3. 7, 8-TCDD decreased based on an
  evaluation of data from an
  interlaboratory study that used Method
  1613. The data were cited and discussed
  (56 FR  60952-60953) in the November 29.
  1991 notice of availability.
   For the reasons cited elsewhere in this
 rule and in the July 25.1990 proposal [55
 FR 30416). the final MCLG for 2. 3. 7.  8-
 TCDD (dioxin) remains at zero mg/1.
 and the final PQL is estimated as five.
 rather than 10. times'the MDL As
 discussed in the November 29,1991
 notice.  MDLs of 6xlO"9 mg/1 and
 4xiO"» mg/1 were obtained with a
 precision of ±12% in an EPA-sponsored
 study. Considering the zero MCLG. the
 high relative health risk, and the low
 probability of occurrence in finished
 drinking water, the final PQL has been
 set at five times the average of the two
 MDLs. The average MDL is 5x10'* mg/
 1—five times this MDL is 2.5 xlO"^ mg/1.
 which rounded up becomes the  final
 PQL of 3 X 10-« mg/1. The final MDL is
 50% lower than the proposed MDL of
 10X10-" mg/1. The final PQL'for dioxin
 is 40% less than the proposed PQL of
 5x10-* mg/1.
   The important use of laboratory
 performance data is to help EPA set
 fixed ranges of ± acceptance limits
 (Table 15) for laboratories to obtain and
 maintain certification. For fourteen of
 the organics covered by today's notice.
 EPA has set the acceptance limits for
certification samples at two standard
deviations based on performance
sample study statistics rather than
defining fixed acceptance limits.
  These limits will permit a reasonable
number  of laboratories to obtain

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'•certification for compliance monitoring
 analyses while ensuring continued
 progress toward more efficient analysis.
   Laboratory performance data for the
 remaining five organic contaminants
 were obtained in the following studies.
 which were also cited in the November
 29.1991 notice. In the first study, the
 lowest concentration of benzo(a)pyrene -
 tested in an EMSL study was 0.002 mg/L
 which is ten times greater than the
 proposed MCL Rather than extrapolate '
 these data, two EPA laboratories tested
 Method 550 for benzo(a)pyrene at the
 proposed MCL of 0.0002 mg/1 [USEPA.
 1991c]. They achieved a very good
 precision of ±6 percent or better. The
 second study concluded that the
 precision for adipate and phthalate
 analysis with Method 506 was relatively
 poor in EMSL PE  studies  [USEPA,
 1991c]. With the solvent changes
 discussed in Section III-B-3a. an EMSL
 laboratory obtained very good precision
 of ±6 percent or better in samples
 spiked near the MCLs. Based on these
 results EPA is citing Methods 506. 550
 and 550.1 as compliance methods in
 today's rule, and  is  permitting individual
 performance evaluation sample study
 statistics to determine the acceptance
 limits (ranges) by setting them at two
 standard deviations around the average
 concentration (Table 15).
    For endrin and the volatile organic
 chemicals, an analysis of laboratory
 performance evaluation data, the mort  •
 recent of which were cited in the
 November 29,1991  NOA. affirm* that
  laboratory performance warrants using
  fixed limits of ±30  percent for endrin.
 The data also support using the fixed
  acceptance limits of ±40 percent for
  three volatile organic chemical*
  included in today's rule—
  dichloromethaoe. 1.2,4-trichlorobenzene
  and 1.1.2-trichloroethane, These are the
  same limits listed in TaUe 18 of the July
  25.1990 notice.
    Several commenters on the NOA data
  for the SOC contaminants expressed
  concern about broad confidence
  intervals (near ±100 percent) and slated
  doubts about PQLs based on such wide
  bands. EPA agrees that the data for
  some contaminants stowed broad
  acceptance bands, and for too**
  contaminants. EPA has established
  acceptance limits as ±2 standard
  deviations of the data developed in PE
  studies. As laboratory performance with
 • these method* improves, si is EPA'*
  expenence with new methods, tfa*   .
 , confidence interral* will narrow,
 *'   4. Laboratory certification. Several
  cormnenter* expressed concern about
   the resources seeded and the time ,
   constrain!* to achieve fuO certification
   prior to the initial  monitoring period lot
newly regulated contaminants. EPA
understands that certification for all
parameters in time to comply with the
initial monitoring deadlines
(specifically, the January 1993-^
December 1995 period in today's rule)
may present some difficulties in some
areas. To alleviate this. EPA is
recommending that Su» te» and -Regions'•. •
grant provisional certification, but only
for recently regulated unalytes. The
provisional certification criteria are not
regulatory in nature. Guidelines for
granting provisional certification are
described in EPA's "Manual for the
Certification of Laboratories Analyzing
Drinking Water" (USEPA. 1990mJ.
  States and Regions are encouraged to
begin certifying laboratories for analytes
as soon as MCLs and certification
requirements for those analytes have
been promulgated. It in not necessary to
wait for MCL* to become effective.or for
the State or Region to  become certified.
Under the Certification Manual a State
is to grant a laboratory provisional
certification only for newly regulated
analytes until the next regularly
scheduled on-site audit after the
effective date of the MCLs or until the
end of the first monitoring period.
whichever comes first. Also, according
to the Certification Manual in order to
be granted provisional certification a
laboratory should currently be certified
to test for other drinking water
parameters, pas* an annual performance
evaluation cample containing the
analytes of interest aiad meet all the
other criteria stated in the rule. States
may add additional requirements that
they deem appropriate. In addition.
States may set criteri« for certifying a
laboratory for the measurement of
dioxin (2J^3-TCDD) with EPA Method
1613.
   EPA wishes to clarify the effective
 date of promulgated analytical method*
 in this rule. A promulgated method or
 method update must be used for those
 analytes for which it was promulgated
 as soon as the MCLs become effective.
 which i* usually 18 months after
 promulgation. However, the method*
 may and should be uced starting 30  days
 after promulgation of the rule* for
 analyzing sample*. Thi* will enable
 laboratories to be well prepared and at
 least provisionally certified when the
 MCLs and monitoring requirements
 become effective.
 5. Selection of Best Available
 Technology
   a. Inorganics. On Jtily 25,1990, EPA
 proposed the best available technolog**
 (BATs) for the removal of tie five
 inorganic contaminants frosa drinking
 water (55 FR 30416). Today's notice
finalize* the*e determinations. Table 16
summarizes the final BATs for the five
inorganic contaminants.

 TABLE 16.—FINAL BAT FOR INORGANIC
           CONTAMINANTS
    Contvmwnt
 j
                          BAT-
Antimony ......... ______ ...
Berytkuni .. ___________ ...
Cyanide ................ - ........
Thallium „
...I C/F; RO.
.... AA; IE; BO: LS. C/F
.... IE. RO: CH.
...' IE. RO: LS.
...; AA: IE.
  1 Best AvadabM Technology (BAT):
  AA » Activated Alumina.
  IE = ton Eichange.
  LS - Lime So«er»ng.
  RO « Reverse Osmosis.
 •C/F  m Coagulation/FtNralion.
  CH.» CMonne Oadaaon.

  The BATs presented in this notice are
the same as in the proposal with one
exception: ion exchange for cyanide
removal is amended to require pH
adjustment for better removal efficiency.
This issue is discussed below in further
detail with the discussions of the other
major concerns expressed during the
public comment period for Jie proposed
rule regarding the BATs for the  IOC*.
  (1) BAT field demonstrations. Several
commenters stated that the proposed
BATs have not been demonstrated
specifically for some of the inorganic
contaminants under field conditions.
These commenters were concerned that
the reliance upon bench-scale and  pilot-
scale data in the absence of field studies
might not meet the requirements of BAT
for these contaminants  under section
1412(b){5)ofrheSLTWA.
  The Agency does not believe that the
SDWA requires field studies as a
prerequisite to establishing BAT for a
contaminant. The SDWA directs EPA to
set the MCL as dose to the MCLG  as
"feasible." The SDWA  defines
"feasible" as "feasible with the use of
the best technology which the
Administrator finds, after examination
for efficacy under field  conditions  and
not solely under laboratory conditions.
 (is] available (taking costs into
consideration)." Section 1412{b)(3){D).
EPA interprets this provision to require
 field trials for a technology, not for the
 application of that technology to each
 individual contaminant Consequently,
 EPA has not required full-scale field
 validation of a technology's feasibility
 for treating a specific contaminant if its
 effectivene** has been demonstrated at
 bench or pilot *cale for that compound.
 The technology, however. mu»t
 reasonably b« expected to perform in •
 similar """«<** nnAar Ocid condition*
 regardleas of aberrations du* to tcale-u
 factors.

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3111ft
..ftd«t«M9g«ter
 57: «o.
                                                               Jdy 17. 1992 / Ruieff and Regulations
   It should also be noted that many of
 the 83 contaminants for which Congress
 required EPA to establish NPDWRs by
 June 19.1989 had never been regulated
 by EPA or treated by public water
 systems. Thus for many of the
 contaminants which Congress  required
 EPA to regulate, the data which the
 commenter asserts are a prerequisite to
 selecting a. technology as BAT do notyet
 exist. The commenter's arguments
 suggest that Congress required EPA to
 regulate many new contaminants within
 3 years of the 1986 amendments but
 effectively precluded EPA from selecting
 any technologies as BAT for the
 regulations. Therefore. EPA believes it is
 appropriate to consider pilot plant and
 laboratory studies to project the removal
 efficiencies for these inorganics that
 would be achieved by technologies that
 have been in full-scale use by public
 water systems for other similar
 contaminants. A detailed discussion of
 the efficiencies of each of the treatments
 can be found in the July  1990 proposal
 and in the "Technology and Costs for
 the Removal of Phase V Inorganic
 Contaminants from Potable Water
 Sources" [USEPA. 1990b].
  While some of the treatments listed as
 BATs in Table 16 are not currently in
 full-scale use to treat specifically for the
 inorganic contaminants in today's
 notice, they are demonstrated
 technologies currently in use to treat a
 variety of drinking water contaminants,
 including previously regulated inorganic
 contaminants. Further, in each case.
 high quality bench- or pilot-scale  data
 obtained under verifiable conditions
 which replicate typical drinking water
 treatment conditions have been
 provided.These data confirm that'the
 treatment efficiencies of these
 technologies are high and that these
 technologies may be properly
 designated as BAT for the inorganic
 contaminants.
  (2) Potential For antimony leaching
 from tin/antimony solder. Several
 commenters were concerned that
 antimony could leach from tin/antimony
 solder joints similar to lead leaching
 from lead/tin solder joints.
  EPA has determined that antimony
leaching from tin/antimony solder does
not present a contamination problem.
EPA has based this determination'upon
 a theoretical analysis of the potential for
 leaching and on three studies that
 investigated antimony levels in water in
contact with tin/antimony-soldered
copper pipe joints [Herrera et al., 1981,
Subramanian  et al., 1991. and USEPA.
1988a].
  When different types of metals are in
contact with each other. gaJvanic
corrosion can occur. In a galvanic
  couple, one metal will serve as the
  anode, which will deteriorate, and the
  other metal will serve as the cathode.
  For copper pipes soldered with either
  lead/tin solder or tin/antimony solder.
  three galvanic couples can exist. For
  lead/tin-soldered copper pipe joints, the
  three couples which exist are: copper-
  tin, copper-lead, and lead-tin. The
 • strongest galvanic couple:of these three--
  will be the copper-lead couple and lead
  will serve as'the sacrificial anode. Thus.
  galvanic corrosion would promote lead
  leaching from a lead/tin-soldered
  copper plumbing joint. For the tin/
  antimony-soldered copper pipe joint, the
  three couples which may exist are:
 copper-antimony, copper-tin, and tin-
 antimony. The strongest  galvanic couple
 of these three will be the copper-tin
 couple and tin will serve as  the
 sacrificial anode. Thus, galvanic
 corrosion would promote tin leaching.
 rather than antimony leaching, from a
 tin/antimony-soldered copper pipe joint
 and very little antimony  would be
 expected to leach. In addition, tin can be
 passivated by tin oxide, which could
 form a passivating film to further inhibit
 antimony leaching from a tin/antimony
 solder joint.
   Laboratory experiments and field
 tests were conducted to verify the
 theory on the  potential for antimony
 leaching from tin/antimony solder joints
 (Seattle Distribution System Corrosion
 Control Study: Volume III. Potential for
 Drinking Water Contamination from
 Tin/Antimony Solder prepared by
 Herrera et al.  for USEPA  (August, 1981)
 [Seattle. 1981] and also reported in
 Herrera et al.. Journal of the American
 Water Works  Association, July 1982)
 [Herrera et al.. 1982].
   The laboratory experiments evaluated
 antimony levels from tin/antimony-
 soldered copper coupons  with
 stagnation times between one-half hour
 to 98 hours. Two coupons of pure
 antimony were also tested with a
 stagnation time of 70 hours for
 comparative purposes. The coupon tests
 demonstrated  that antimony dissolution
 was several orders of magnitude lower
 than the dissolution from  pure antimony
 metal even though the stagnation time
 was longer (98 hours versus 70 hours).
 The highest antimony concentration
 observed in the tin/antimony coupon
 testing was 3.7 fig/1, which is below the
 MCLG promulgated in this noticed for
 antimony. In addition.'tin  oxides were
 found adhering to areas on the solder,
 which'may provide additional inhibition
 of antimony leaching from tin/antimony
solder.
  Field tests were conducted at the
University of Washington where tin/
antimony solder has been used for
                                                                  building plumbing systems since 1968.
                                                                  Samples (0.9 liter) were taken at the
                                                                  point where the distribution system
                                                                  entered the building to obtain the
                                                                  characteristics of the inflow water.
                                                                  Several commenters stated that these
                                                                  were the only type of samples taken and
                                                                  claimed that the study did not evaluate
                                                                  the leaching potential of .the plumbing.., -
                                                                  However, overnight standing samples
                                                                  (0.9 liter) were taken at the tap located
                                                                  the furthest distance from the entry
                                                                  point to the building. The plumbing
                                                                  systems ranged from 1 to 10 years in
                                                                  age. Thus, the contribution of antimony
                                                                  leaching from  tin/antimony soldered
                                                                  copper pipe joints was evaluated by
                                                                  comparing the results from the ovemighi
                                                                  tap sampling with the building inflow
                                                                  sampling results. A difference in
                                                                  antimony concentrations between the
                                                                  overnight tap sample and the building,
                                                                  inflow sample was observed in only one
                                                                  of the eight buildings where sampling
                                                                  was conducted. The concentration of
                                                                  antimony in that overnight  tap sample
                                                                  was below the MCLG. AH of the other
                                                                 antimony concentrations were below
                                                                 the detection limit. In addition, tin oxide '
                                                                 films were found on three solder joints
                                                                 which were removed from a building's
                                                                 plumbing system. These films could
                                                                 have contributed to the inhibition of
                                                                 antimony leaching from these joints
                                                                 [Herrera et al., 1981].
                                                                   The commenters noted that the study
                                                                 conducted at the University of
                                                                 Washington evaluated only one type of
                                                                 water quality. However. Seattle's
                                                                 finished water quality, at the time of this
                                                                 study, was corrosive, yet significant
                                                                 antimony leaching from tin/antimony
                                                                 solder was not  observed under these
                                                                 conditions. In fact, all of the antimony
                                                                 concentrations  measured in this study
                                                                 were below the MCLG and most were
                                                                 below the detection limit. The amount of
                                                                 antimony leaching from tin/antimony
                                                                 solder would be even less in non-
                                                                 corrosive waters.
                                                                  This was confirmed by another study
                                                                 which evaluated the impact of several
                                                                 water qualities on antimony leaching
                                                                 from tin/antimony solder with various.
                                                                 stagnation times (Impact of Lead and
                                                                 Other Metallic Solders on Water
                                                                 Quality, prepared by Murrell for USEPA.
                                                                 July, 1988) [USEPA. 1988a]. In this study,
                                                                 a pipe loop was constructed with tin/
                                                                 antimony-soldered joints to evaluate the
                                                                effect of water quality or antimony
                                                                leaching from tin/antimony solder. Four
                                                                waters with the following
                                                                characteristics were evaluated with
                                                                varying stagnation times to determine
                                                                their effect on antimony leaching from
                                                                tin/aMfirnony solder (1) pH between 5.1
                                                                and 5.3; (2) pH between 6.3 and 6.6; (3)

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             Federal Register / Vol. 57. No.  138 / Friday. July 17. 1992 / Rules and Regulations
pH 7.4; and (4) pH between 8.5 and 8.6.
The stagnation times evaluated in this
study were 4 hours. 8 hours. 12 hours. 24
hours, and 4 weeks. Six samples were
taken at each pH and stagnation time
combination.
  For the two higher pH ranges, where
the pH was above.pH7.0.all of the,
samples had antimony concentrations
below 4 fig/1 for stagnation times up to
24 hours. All of the samples for the
lowest pH range also had antimony
concentrations below 4 /xg/1 for
stagnation  times up to 24 hours. For the
second lowest pH range (pH between
6.3 and 6.6). results at 4 ng/\ and above
were observed at  stagnation times
below  24 hours. One of the six samples
with a stagnation  time of 12 hours
exceeded the final MCLG and three of
the six samples with a 24-hour
stagnation time exceeded the MCLG.
However. EPA believes that systems
with such a low pH would likely fail.to
meet the requirements of the recently
promulgated lead and copper rule (June
7.1991. Federal Register [56 FR 26460]).
Those  systems would therefore likely
need to increase the pH of the finished
water to comply with that regulation.
Finished water with a pH above pH 7
did not produce antimony
concentrations above the MCLG in this
study and this water quality is a likely
minimum necessary to comply with the
lead and copper rule.
   EPA also believes that this study
addresses  several commenters' concerns
about antimony leaching from newly
soldered joints. The commenters
apparently believe that antimony
leaching from tin/antimony solder could
be similar to lead leaching from lead/tin
 solder and thus were concerned that
 significant concentrations of antimony
 could leach from newly soldered joints.
 As discussed above, antimony leaching
 from newly soldered joints was not
 observed in non-acidic waters which
 will predominate as systems comply
 with the lead and copper rule
 requirements.
   The effect of water quality on
 antimony  leaching from tin/antimony
 solder was also investigated in
 Subramanian, Conner and Meranger.
 Journal of Environmental Science and
 Health, 1991 [Subramanian et aL 1991].
 This study investigated the effect of
 three  water qualities on metals leaching
 from four non-lead-based solders. The
 amount of metals leaching from newly
"soldered joints was evaluated using high
 purity, tap, and well water samples with
 various standing times. The pH of the
 high-purity water was 6.8. The pH and
 alkalinity of the tap water was 7.8 and
 30 mg/1 (as CaCOj). The pH and
alkalinity of the well water was 8.1 and
155 mg/1 (as CaCOa).
  The amount of antimony leached into
samples was at or below the detection
limit of 1.2 mg/1 for standing times up to
7 days, regardless of the water quality.
For the high-purity and well water
samples, there was.nodetectable ...
leaching of antimony with standing
times longer than 7 days. However, the
amount of antimony leached into tap
water after 14. 28. and 90 days of
contact  was 2.0. 3.7. and 7.3  Mg/l-
respectively. EPA does not believe that
such unusually long standing times are
typically encountered in public water
supplies. Thus, this study supports
EPA's position that antimony leaching'
from tin/antimony solder joints should  '
not be a problem.
  (3) Disposal of wash brines from ion
exchange and reverse osmosis
treatments in water-scarce areas.
Commenters expressed concerns
regarding the potential costs associated
with disposal of wastes (particularly
brine wastes) generated by  treatment
processes which remove inorganics. Of
particular concern are waste brines
generated by reverse osmosis (RO) and
ion exchange (IE] processes. One
commenter expressed concern about the
environmental impacts as well as the
potential impact of waste water
treatment on  water conservation
concerns in water-scarce regions. For
example, reverse osmosis results in loss
of a percentage of the influent water as
brine.
  EPA does not agree with the
commenter's  assertion that
environmental impacts (discussed
below) would be extreme if a low
sulfate standard (i.e., 400 mg/1) were
promulgated. The Agency believes that
water wastage could be minimized by
treating only  a portion of source water
containing elevated sulfate  levels.
blending the treated water with source
water, and by further treating brine
wastes. Waste volume reduction and
waste handling options appear not to
have been fully considered  by
commenters. Other very conservative
assumptions  were employed by the
commenter which led to conclusions not
shared by EPA. The commenter'o
assumptions  include: An increase in
Colorado River,sulfate levels beyond
 recent historical levels: and the overall^
 importance of that source to the
Southern California supplier, when
 competing entitlements to that river
 source may diminish the supplier's share
 of available river water.
   One commenter stated that there are
 potential economic impacts where
 limited disposal option* exist The
Agency agrees with the commentei
cheaper options (such as direct
discharge into a receiving body of
water) are not always available. F<
these reasons. EPA has included se
waste treatment and waste dispose
options in its analysis and incorpot
costs for all projected systems in tb
Regulatory Impact Analysis (RIAf
Document developed for this rule
[USEPA. 1992d]. These costs are a
substantial part of the overall estin
treatment costs for meeting the drit
water MCLs.
  Commenters raised questions ab
competition for scarce water in cer
regions, the need for source water
protection measures  (i.e.. pollution
prevention), and waste quantity an
quality that may limit disposal opti
EPA has addressed these concerns
this rulemaking and in previous act
(Federal Register. Vol. 56. No. 20. p;
3553-3554) and does  not believe the
data and assertions presented in
response to the July 1990 proposal <
sufficient to raise regulatory concet
  (4) Alkaline chlorination treatme
cyanide. Several commenters were
concerned about the potential for
increased concentration of
trihalomethanes resulting from the
alkaline chlorination treatment for
cyanide. For systems whose raw w
has a high trihalomethane formatio
potential. EPA agrees that this trea'
could exacerbate the problem. How
systems can choose to install ion
exchange or reverse  osmosis, whicl
would be less likely  to significantly
increase trihalomethanes.  As statec
the proposal, the highest observed
occurrence level for cyanide in drin
water (8 fig/1) is considerably lowe
than the MCL for cyanide  (200 ^g/l
Therefore. EPA expects that few. if
systems would need to install treat!
for cyanide and that increased
trihalomethanes resulting  from a
cyanide BAT is unlikely to be a
widespread problem.
  (5) Ion exchange as BA Tfor cyan
Several commenters stated that ani
exchange would not remove cyanid
because at the near-neutral pH vah
for most drinking waters, cyanide is
much more likely to  be present as f-
rather than CM. EPA agrees with th
commenters' assertions that anion
exchange would only likely remove
cyanide that is present as CN. EPA
believes, however, that systems tha
need to can increase the pH of theit
water to further dissociate HCN to i
The ion exchange data presented in
Technology and Cost Document ind
that ion exchange can efficiently rei
dissociated cyanide [USEPA. 1990b

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  J3812       Fedend Regbter / Vol. 57. No. 138 / Friday. July 17. 1992  /  Rule* and
  Cyanide is dissociated at lower pH
  levels than those cited in some of the
,  studies in the Technology and Cost
  Document. EPA has provided the
  treatment costs for pH adjustment (see
  Lead and Copper in Drinking Water as a
  Result of Corrosion: Evaluation of
  Occurrence. Cost and Technology. 1991-
  IUSEPA. 1991aj). An option for systems
  using ion exchange for cyanide removal
  would be to adjust the pH to dissociate
  and remove the cyanide and then lower
  the pH somewhat prior to chlorination
  and distribution. EPA believes this
  approach to be a more effective way to
  address  cyanide removal in waters with
  significant trihalomethanes (THM)
  formation potential than alkaline
  chlonnation. Nevertheless, for the
  reasons  provided in the discussion of
  alkaline  chlorination. EPA does not
  believe (hat increased trihalomethanes
  resulting from a cyanide BAT will be a •
  widespread problem when using that
  method.
    (6) Sulfate reverse osmosis costs.
  Several commenters questioned why the
  total treatment costs for sulfate removal
  by reverse osmosis were lower than the
  total treatment costs for the inorganic
  contaminants in this rule. The MCLs
  proposed for sulfate were several orders
  of magnitude higher than the MCLs for
  the inorganic contaminants in this rule.
  EPA assumed that systems would blend
  a treated portion and an untreated
  portion to reduce the total production
  costs for  sulfate. EPA believes that only
  in extreme cases would systems require
  both high removal efficiency and
  treatment of the entire influent flow.
  Thus, systems  were only assumed  to
  treat a part of the product water to
  remove sulfate rather than the entire
  product flow as is assumed in the T*C
  document for the other inorganic
  contaminants.  However, as was noted in
  the Juiy 1990 proposal, blending to
  reduce total treatment costs is an option'
  tor systems using RO for the other lOCi.
  Since a smaller volume of water is being
  treated, capital costs and operation and
  maintenance costs would be lower.
  resulting  in lower treatment costs  than
  estimated.
   (7) Sulfate ion exchange costs. Several
  commenters questioned why the total
  production costs for sulfate removal by
  anion exchange were higher than the
  total production costs for cyanide
  removal by anion exchange. The
  difference in the total production coatt
  for these  two inorganic contaminant*
  resulted from higher operation and
  maintenance costi for sulfate removal
  associated with resin regeneration. The
  increased regeneration co«ti are due to
 faster saturation if the r«in b«cau«« of
  the significantly higher levels of sulfate
  that would be treated to meet the
  proposed MCL levels compared to the
  levels of cyanide.
    b. Synthetic organic contaminant.
  MCLs In the 1988 SDWA amendments.
  Congress specified in section 1412(b)(5)
  that."Granularactivated--carb'on:is •  ••
  feasible for the control of synthetic
  organic chemicals, and any technology,
  treatment technique, or other means
  found to be best  available for the
  control of synthetic organic chemicals
  must b'e'at least as effective in
  controlling synthetic organic chemicals
  as granular activated carbon." On July
  25.1990. the Agency proposed the best
  available technology (BAT) for the
  removal of the 18 synthetic organic
  chemicals (SOCs) from drinking water
  [55 FR 30420). Today's notice
  promulgates the final rule for these
 contaminants, including identification of
  the Bat. Table 17 provides a summary of
 the proposed and final BATs.

  TABLE 17.—PROPOSED AND FINAL BAT
      FOR ORGANIC CONTAMINANTS
Contaminant
DH2-«thyln«*yf)
atfoatr
Oalaoon 	 _ 	 	
Dicritorom««n2o-p-diojan —
1.2.4-
TncttorotMonn*.
1. 1.2-
TncttorocttWM.
PropOMd
BAT
GAC/PTA
GAC
PTA
GAC
GAC
GAC
GAC
GAC
GAC
GAC/PTA
GAC
GAC
GAC
GAC
GAC
GAC
GAC/PTA
GAC/PTA
FmalBAT
GAC or PTA
GAC
PTA
GAC
GAC
GAC
GAC
OX
GAC
GAC or PTA
GAC
GAC
GAC
GAC
GAC
GAC
GAC or PTA
GAC or PTA
  GAC—Granular Activated Carbon.
  PTA—Pack*! Towvr Aaratnn.
  OX—OnMkon (Chtonn* or Ozcrw)

  With one exception, the BAT
presented in today's notice is the same
as proposed in July 1990. The exception
is glyphosate. The BAT for glyphosate
was proposed as granular activated
carbon (GAC) but has been finalized as
oxidation. This change U discussed
below.
  The BAT* for organic* in today's final
rule listed in Table 17 are discussed in
detail in the Technology and Coit (T&CJ
document contained in the rulemaJdng
docket [USEPA, 1992e£ In the T&C
  document the available technologies are
  discussed, a summary of the literature
  documenting treatment performance is
  provided, and the cost estimates of BAT
  are detailed. The information presented
  in the T&C document, including the
  availability of.a technology,,!!*'.••••.- ?•'••':
  performance, and an estimated cost of
  compliance of using the technology are
  all considered and form .the basis for
  determining the final BATs for the SOCs
  in today's rule.
   The following discussion addresses
  the major concerns expressed during the
  public comment period for the July 25.
  1990 proposed rule regarding the
  proposed BATs for the SOCs.
   (1) BAT field evaluations. A number
  of commenters expressed concern that
  the BAT proposed for the SOCs had not
  been demonstrated to be effective
  according to the criteria set forth by the
  SDWA. They recommended that the
  Agency conduct field testing of all the
  SOCs under various conditions to
  determine the effectiveness of the BATs
  as proposed.
   The SDWA directs EPA to set the
 MCL as close to the MCLG as
 "feasible." The SDWA defines
 "feasible" as "feasible" with the use of
 the best technology. . . which the
 Administrator finds, after examination
 for efficacy under field conditions and
 not solely under laboratory conditions.
 [isj available (taking cost* into
 consideration)." As mentioned above,
 EPA interprets this provision to require
 field trials for a technology, not for the
 application of that technology to each
 individual contaminant. Consequently,
 EPA has not required full-scale field
 validation of a technology's
 effectiveness for treating a specific
 contaminant if its effectiveness has been
 demonstrated at bench or pilot scale for
 that compound. The technology.
 however, must reasonably be expected
 to perform in a similar manner under
 field conditions after considering
 aberrations due to scale-up factors.
  For three of the contaminant! In the
 July 1990 proposal (di(2-
 ethylhexyl)adipate and endothall and
 2,3,7,8-TCDD), EPA relied on model
 prediction* based on the compounds'
 physical/chemical characteristics, to
 specify GAC ac BAT. At the time of
 proposal treatment performance data
 were not available due to analytical
 difficulties with (di(2-ethylhexyl)adipate
 and endothall. Since proposal, however.
 the Agency has obtained treatment
performance data for these two
compounds. The treatment performance
studies and data for both (m[2-
ethylhexyljadipate, endothall are
included te the Technology and Co*t

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             Federal  Register / Vol. 57. No. 138 / Friday, fuly 17. 1992 / Rules and  Regulations       31813
Document contained in the rulemaking
docket [USEPA. 1992e). The results of
the studies on these two compounds
support earlier BAT determinations of
GAG made using the model. Further, the
SDWA states that GAG is feasible for
the control of SOCs.
  With.respect to.dioxin.,there is a.piloK
scale treatment performance study
indicating removal of diox'n from Agent
Orange using GAG (Chemical Eng..
1977). This study has limited
applicability since the solvent is not
water, but due to the associated health
risks during analysis of dioxin. the
treatment performance of GAG was
determined based solely on the model
predictions.
  The Agency is designating GAG as
BAT for dioxin in today's rule in spite of
the lack of performance data. GAG has
been statutorily designated as "feasible
for the control of synthetic organic
chemicals" (section 1412(b)(5). SDWA)
and the results from model predictions
based on the physical/chemical
properties of dioxin support this
determination. In light of the SDWA
statement that GAG is feasible and the
fact that GAG has proven to be effective
in the laboratory and under full-scale
conditions for other synthetic organic
contaminants of similar characteristics.
the Agency believes it is appropriate to
establish GAC as BAT.
   Cost considerations. One commenter
 stated that a BAT must be evaluated
 and applied to site-specific conditions
 and that estimated costs might not be
 representative of actual operating
 conditions.
   In response, costs at specific sites
 may be higher than estimated in the
 Cost and Technology Documents. The
 design and costs of the treatment
 technologies evaluated as part of the
 T&C document pertain to an average
 system (not-worst case), and are meant
 to be used for a system's preliminary
 planning purposes, for generating
 national cost estimates and for
 determining affordability for typical
 systems. Worst-case cost estimates are
 not used because the Agency does not
 believe that such estimates would
 accurately represent the affordability of
 treatment for large water suppliers on a
 national basis. Individual systems •
 should develop a  more complete and
 detailed design and cost evaluation
 based on pilot-plant testing and site-
 specific considerations. The cost
 estimates presented in the T&C
 document provide a basis that can be
 used by any system regardless of water
 quality.
    Use of other technologies. One
 commenter noted that treatment
 facilities are free to choose technologies
other than BAT to meet the MCL Other
technologies may be chosen in lieu of
BAT because they may be more cost
effective or better suited to the specific
operating condition!! of the particular
site to meet the MCL Making the choice
not to use BAT. however, means that a
system will not be eligible for.a variance
under SDWA section 1415. For example.
if a facility does not install GAC where
it is the designated BAT. but uses PAG
instead, and fails to meet the MCL. the
facility would not be eligible for a
variance. On the other hand, the same
facility may be eligible for an exemption
under SDWA § 141tt if for example GAC
could not be installed due to an inability
to obtain financing and PAG was used
instead, and the facility failed to meet
the MCL
  EPA agrees with commenters that
GAC. and any other treatment
technology for that matter, can create
problems if not properly maintained and
operated. Again, technologies other than
GAC. PTA or OX can be used if they
seem better suited to site-specific
conditions in order to achieve the MCL  .
   Carbon  disposal costs. Some
commenters were concerned that the
cost of disposal of spent carbon was not
taken into account at all in the costing
assumptions for  the design and
operation  and maintenance (O&M) for a
facility. The cost of carbon "disposal" is
essentially the cost of regenerating the
spent carbon (and replacing the 12 to 15
percent lost in the process). For plants
whose daily carbon use is less than
1.000 pounds per day. EPA assumes that
the carbon would be regenerated off-site
by the carbon supplier and that cost is
included in the cost: of.replacement
carbon. For plants whose carbon
demand is more  than 1,000 pounds per
day, it is generally economical to
regenerate on-site. The cost of the
incinerator used to regenerate the
carbon and its operation and
maintenance costs are part of the
 facility capital and O&M costs already
 factored into total costs. The revised
 model that EPA  now uses in developing
 costs [Adams and Clark. 1989] factors
 into total  costs the expense of carbon
 regeneration and replacement.
   When powdered activated carbon
 (PAG) is used, it is usually disposed of
 with the alum sludge in a sanitary
 landfill. Because this rule does not
 consider PAC to be BAT, EPA is not
 addressing the issue of PAC costs,
 including the costs of disposal.
   PTA and air emissions. One
 commenter stated that it is possible to
 transfer risk from water to air when
 using PTA. As th« commenter points out.
 there is a possibility of transferring the
 risk associated with VOCs from water
 to air when using PTA as a treatment
 technology (and that increased costs
 may result from a requirement to also
 treat the PTA emissions). EPA agrees
 that control of such air emissions may
 be required by regulations outside the
 SDWA (e.g.. local or State regulations)
. and could.increase.the costs, of this •••• .'-•-'
 technology. Consequently, the cost of
 controlling emissions was estimated  as
 a separate cost item in Table 13 of the
 July 1990 notice and was included in
 chapter 7 of the proposed and final T&C
 document [USEPA. 1992e|. These
 emission control costs can be added  to
 the PTA costs to get an estimate of the
 total costs. The costs are based on
 treatment by vapor-phase GAC.
   Empty bed contact time. A number of
 commenters expressed concern about
 the use of an empty bed contact time
 (EBCT) of 7.5 minutes and urged field
 studies to identify an EBCT or range  of
 EBCT values. A reference cited in the
 July 1990 proposal on general
 information about the parameters of  the
 cost model may have misled these
' commenters. The values used to satisfy
 the variables of the parameters were
 stated in the T&C document. The EBCT
 was used for estimating cost of GAC
 removal of SOCs in the July 1990
 proposal and in today's rule, and the
 EBCT was assumed to be 10 minutes;
 not 7.5 minutes. For additional
 information on the basis for the use.of a
 10-minute contact time. EPA refers
 readers to the January 30.1991 rule [56
 FR 3555] and-supporting documents.
   Carbon usage rate. Some commenters
 stated that natural organic matter is  a
 major contributor to the carbon use rate
 (CUR). The concern was that costs of
 carbon replacement and regeneration
 would be much higher in actual practice
 than those calculated in theory. The
 Agency agrees with these commenters
 that natural organics contributes to the
 CUR. To account for the competitive
 adsorption and fouling of GAC by these
 organics present in the water matrix.
 EPA used an adjusted CUR in both the
 proposed and final rules. The CURs are
 calculated using an equation derived
 from the Freundlich isothermal
 relationship and a mass balance for
 each specific SOC based on distilled
 water isotherm data. The CUR is then
 adjusted by comparison of field to
 distilled water usage rates to account
 for the competing effects of natural
 organic*. The method used  to determine
 and adjust the CUR is presented in
 Chapter 4 of the Technology & Cost
 Document [USEPA, 19S2e] and is a
 reasonable approximation of the effects
 of natural organic*. The'CUR as well as
 the adjusted CUR provide a mechanism

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 31814       Federal Regbter  /  yol. 57. No. 138 / Friday. July 17. 1992 / Rulea and Regulation!
to compare relative absorbabilities, and
ultimately, relative'costs. The Agency
recommends that each system use its
own water quality  and geographical
conditions, as well as the appropriate
EBCT and CURs as part of their design
considerations. EPA discussed  these
same issues :n its Phase.II final      •
regulation (January 30.1991 [56 FR
3556 J).
  Powdered activated carbon as BA T.
One commenter suggested that  PAC be
considered BAT since it can be used for
removal of pesticide contamination in
surface waters and is the same
substance as GAC. EPA's position is
that the use  of PAC may be  an
appropriate  choice of technology in
certain instances. PAC treatment of
surface water that is only intermittently
contaminated by pesticides  or other
SOCs could  be both economical, in
combination with an existing filtration
plant, and effective.
  While PAC has proven effective in
taste and odor control, its efficacy for
trace SOC removal in drinking water is
variable due to factors such as carbon
particle size, background organics. and
plant efficiency. Therefore. EPA does
not believe that PAC is as effective as
CAC overall, and the Agency has not
designated it as BAT. If application of
PAC will reduce the contaminant below
the MCL in particular cases, it may be
used in lieu of the designated BAT (for
example, if the utility finds that PAC is
more cost effective}. See discussion
above on use of these technologies in
lieu of BAT.
  BATforglyphosate. As presented
earlier in today's notice, the BAT
proposed forglyphosate was GAC. One
commenter stated that GAC is not BAT
for glyphosate and indicated that
conventional treatment is more  effective
Jn removing  this compound from
drinking water. Conventional treatment
typically combines  disinfection  (usually
chlorine), coagulation, flocculation.
sedimentation, and filtration. EPA
agrees that other technologies appear to
provide better treatment removal
efficiencies for glyphosate than  GAC
and conducted additional bench- and
pilot-scale studies to evaluate and
determine  the BAT. As the commenter
suggests, and as we determined from
subsequent study. GAC is not effective
in removing glyphosate from drinking
water. Bench-scale  treatability studies
documented by Speth (Speth. 1990]
indicate that oxidation using
chlorination  (potentially as part of
conventional treatment) or oronation
were significantly more effective
treatment techniques for glyphosate
than is GAC. EPA stated in th«
 November 1991 NOA (56 FR 609541 that
 it was considering designating these
 technologies instead of GAC as BAT for
 glyphosate. Today. EPA is identifying
 oxidation (using chlorination or
 ozonation) instead of GAC as BAT for
 glyphosate.
•   The proposed BAT was-based OIF
 treatment evaluations conducted using
 distilled water and a limited number of
 data points.  Subsequent bench-scale
 analyses [Speth. 1990) revealed that
 glyphosate's behavior in natural waters
 is unlike that of any of the other SOCs
 associated with this rulemaking.
 Glyphosate exhibits very different
 treatability characteristics in distilled
 water than in natural waters. This is
 thought to be due to  extremely slow
 kinetics and the influence of organo/
 metallic complexation. These additional
 studies also provided a  preliminary
 examination of the effectiveness of
 various other treatment methods for
 removing glyphosate. The results
 indicated that carbon did not remove
 glyphosate under raw water conditions.
 but oxidation, specifically chlorine or
 ozone, was very effective. These bench-
 scale studies also seemed to suggest that
 under some conditions glyphosate could
 be removed by membranes and
 coagulation/filtration. These bench
 scale studies were completed too late
 for inclusion in the July 1990 proposal.
 EPA made these bench-scale studies
 available for public comment in the
 November 1991 NOA.
   During 1991, the Agency conducted
 pilot-scale studies to further evaluate
 the effectiveness of conventional
 treatment (including  chlorination and
 ozonation). The results of the pilot
 studies demonstrated that lower levels
 of glyphosate were detected after
 chlorination or ozonation. The pilot
 study also showed, however, that
 conventional treatment,  which typically
 combines disinfection (usually by
 chlorine), coagulation/flocculation/
 sedimentation and filtration, has not
 added effect over chlorination or
 ozonation. The results of these pilot-
 scale studies were too late to be
 included in the November 29,1991 NOA
 [56 FR 60954J.
   One'commenter raised a number of
 concerns in response to the November
 1991 NOA regarding the  designation of
 oxidation as BAT for glyphosate. The
 commenter argues that by selecting
 chlorination (or oxidation by chlorine)
 as BAT the oxidation by-products
 themselves may  present  health risks and
 may need to be regulated under the
 SDWA in  the future. The commenter
 goes on the state that the ccwU
 associated with the treatment
  modifications that would be required to
  accommodate an oxidation process
  could be appreciable. In addition, public
  water suppliers already have to contend
  with the Surface Water Treatment Rule
  (SWTR). disinfection by-product (DBP)
  concerns, and upcoming DBP regulation.
  The-commenter also states-'that-the •'•'•'••''•
  bench-scale studies included in the
  public docket of the NOA [Speth. 1990|
  indicated that conventional
  coagulation/flocculaticn/sedimentation
  was being overlooked by the Agency.
  and that additional studies should be
 conducted, beyond bench-scale, to
 evaluate the effects of pH. coagulant.
 water matrix, etc.. on the removal of
 glyphosate,by conventional methods.
   As mentioned earlier in response to
 comments, the Agency conducted
 follow-up pilot studies to evaluate the
 effectiveness of the various treatment
 alternatives identified by Speth [Speth.
 1990|. While chlorination used as a
 treatment method could raise concerns
 of associated health risks due to
 disinfection by-products (DBPs). these
 concerns can be addressed through
 effective precursor removal. This
 approach is fully consistent with EPA's
 anticipated approach in the  upcoming
 DBP regulations. To the degree existing
 disinfection also accomplishes oxidation
 of glyphosate. little or no cost would be
 incurred. Installation of new disinfection
 has  been costed and the cost considered
 acceptable..Further, the option to choose
 a treatment technology other than the
 BAT to meet the MCL when
 necessitated by specific conditions is
 available (see earlier discussion of
 selection of technologies other than
 BAT). Also, consistent with the
 commenter's recommendation to do
 additional pilot-scale studies to evaluate
 conventional treatment, including
 coagulation/filtration/sedimentation,
 EPA has  now conducted such studies as
 described above, and based on these
 studies. EPA has decided not to identify
 those technologies as BAT.
  The BAT for glyphosate is determined
 to be oxidation. Details of the
 treatability studies conducted in support
 of selecting a BAT for glyphosate can be
 found in the Technology 4 Cost
 Document [USEPA, 1992e| for the SOCs.
  BA Tfor Di(2-ethylhexyl)adipate and
endothall. As stated earlier in today's
notice, proposed BAT for di(2-
ethylhexyljadipate and endothall was
GAC and is not being changed by
today's notice. One cormntinter stated
that EPA  should use treatability study
data instead of relying solely on model
predictions to select BAT for di(2-
ethylhexyl)adipate. The proposed BAT
for di(2-
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              Federal Register  / Vol. 57. No. 136 / Friday. July 17. 1992 / Rules and Regulations       318
 endothatl was based on model
 predictions due to .analytical problems
.encountered during the earlier treatment
 evaluations. The Agency recently
 conducted additional treatability studies
 to provide additional support for the
 selection of GAG as. BAT.for these..- •
 compounds. ••  '
  The treatability studies for di(2-
 ethylhexyl)adipate and endothail
 demonstrate that GAG is as effective in
 removing these compounds from
 dnnking water as predicted by the
 model. In addition, the SDWA section
 1412(b)(5) states that GAG is feasible for
 the control of SOCs. Therefore, the BAT
 for these compounds remains GAG.
 Details of the treatability studies
 conducted for di(2-ethylhexyl)adipate
 and endothall can be found in the
 Technology &  Cost Document for the
 SOCs [USEPA. 1992E].
  BATforBenzofa/pyrene. One
 commenter suggested that PAC should
 be used  to remove PAHs. As indicated
 in theT&C document, however. PAHs
 can be removed more effectively using
 GAG than by other technologies:
 therefore, the Agency has defined only
 GAG as  BAT for PAHs. However, any
 other technology  that seems  better
 suited to the particular operating
 conditions of the  particular site can be
 chosen as long as the MCL for the
 particular SOC is met. See above for a
 discussion of the  use of other
 technologies in lieu of BAT.
 6. Determination of MCLs
  EPA proposed MCLs for 24 chemicals
 based upon an analysis of several
 factors, including:
  (!) The effectiveness of BAT in
 reducing contaminant levels  from,
 influent  concentrations to'the MCLG.
  (2) The feasibility (including costs) of
 applying BAT. EPA considered the
 availability of the technology and the
 costs of  installation and operation for
 large systems.1
   (3) The performance of available
 analytical methods as reflected in the
 PQL for  each contaminant. In order to
 ensure the precision and accuracy of
 analytical measurement of contaminants
 at the MCL. the MCL is set at a level no
 lower than the PQL
   After  taking into account the above
 factors.  EPA then considered the risks at
 the MCL level for the EPA Group A and
 B carcinogens to  determine whether
 they would be adequately protective of
 public health. EPA considers a target
 risk range of 10~4 to 10"* to be safe  and
 protective of public health when
   1 EPA alto evaluates the national cost* and com
 lo tnuller lytiemt in its analyti* of economic
 Impact!
calculated by the conservative linear
multistage model. The factors EPA used
in its analysis are summarized in Table
18 for the Category11 and Table 19 for
the Category II and III contaminants.
respectively.
  a. Inorganic contaminant A/CLtThe''
MCLs for the inorganic contaminants  '
promulgated today are at the same level
as the promulgated MCLG for each
contaminant, except for thallium (see
Table 1). Also. EPA is deferring action
on sulfate. and no sulfate MCL is
promulgated today.
  The July 1990 notice proposed
alternative PQLs or MCLs for antimony
and thallium. 7\lternative PQLs/MCLs of
0.005 mg/1 and 0,01 mg/1  were proposed
for antimony based on multiples of 5
and 10 times the MTJL As discussed
above, however, the final PQL for
antimony is not being set as a multiple
of the MDL but rather is being set at
0.006 mg/1 based on new PE data
[USEPA,l991d]. This PQL is equal to the
final MCLG for antimony, as  discussed
in section III-A. The Agency  is.
therefore, finalizing the MCL at the same
level as the promulgated MCLG of 0.008
mg/1 for this contaminant.
  The Agency proposed alternative
MCLGs/MCLs for sulfate of 400 mg/1
and 500 mg/1. Today EPA is deferring
promulgation of a sulfate MCL because
the Agency believes it needs  to consider
innovative approaches to regulating
sulfate. The length of this deferral period
will be determined  in the course of
ongoing litigation with an interested
citizen's group concerning EPA's legal
deadlines for establishing regulations
for drinking water contaminants. Unlike
most drinking water pollutants, sulfate
appears to be primarily of concern for
Unacclimated transient populations (as
well as for infants).
  Because of the high cost of regulating
sulfate. its relatively low risk, and its
impact primarily on the transient
consumer. EPA is deferring the
promulgation of the sulfate MCLG and
MCL In the interim. EPA intends to
resolve the following  issues: (1) Whether
further research is needed on how long
it takes infants to acclimate to high
sulfate-containing water. (2) whether
new regulatory approaches need to be
established for regulating a contaminant
whose health effect is confined largely
to transient populations,  and (3) whether
the Agency should revise its definition
of Best Available Technology for small
systems (i.e., what should be considered
affordable for transient noncommunity
water system*).
.  During this deferral period, the
Agency also intends to consider ways to
expedite the proceas for granting
potential exemptions and variances to
 ease the impact of eventual regulations
 on small systems. Also in the interim.
 the Agency plans to issue a Health
 Advisory and encourage States whets
 sulfate levels may be high to conduct
 additional monitoring and encouragetfh
" use of alternative-water supplies where
 appropriate.
   For thallium, alternative PQLs/MCLs
 of 0.002 mg/1 and 0.001 mg/1 were
 proposed in the July 1990 notice based
 on 5 and 10 times the MDL As
 discussed above, however, the  final RQI
 and MCL for thallium is being set today
 at 0.002 mg/1 based on new PE  data
.[USEPA. 1991d]. The. MCL for thallium-ii
 limited by the sensitivity of available :
 analytical methods (i.e.. it is being set^at
 the PQL). The PQL constraint results in
 an MCL higher-than the 6.0005 mg/1
 MCLG by a factor of 4. However, the
 Agency has concluded that the
 promulgated MCL is adequately
 protective of health because the MCLG
 includes a large cumulative safety  factor
 of 3.000. Thus. EPA believes that "the
 health risks of exceeding the MCLG up
 to the MCLare minimal.
   EPA has determined that each
 inorganic contaminant has one  or more
 BATs to reduce contaminant levels to
 the MCLG. and that the BAT(s) is
 feasible (as defined by the Act).
analytical methodologies are available
 to ensure accurate and precise
measurement for each MCL and each
MCL adequately protects public health.
EPA also calculated the household cost
for water suppliers to remove IOC
contaminants to or below the MCLs.
based on the identified BATs. The
inorganic contaminants are not expected
to occur in the very large water systems
and household costs were not estimated
for them. In the largest systems where
they may occur (25.000-50,000
population), costs were approximately
$100/household per year, and would
likely be lower for larger systems. EPA
believes these costs are reasonable.
Also, the national costs associated with
the MCLs for these contaminants, as
shown in the RIA. are considered
reasonable. Also, the national costs
associated with the MCLs for these
contaminants, as shown in the RIA. are
considered reasonable.
   B. Synthetic organic contaminant
MCLa—(1) Category I contaminants.
EPA considered the same factors in.
determining the proposed MCLs for
Category I contaminants as for  Category
II and III contaminants. However, the
proposed MCLGs for Category I
contaminant* are zero, a level that by
definition is not "feasible" because no  -
analytical method is capable of
determining whether a contaminant

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31816
Federal  Register / Vol. 57. No.  138 / Friday. July 17. 1992  /  Rules and Regulations
level is zero. The lowest level that can
be reliably measured is the'PQL. EPA
calculated PQLs for these contaminants
from available analytical performance
data, as described above.
  In developing MCLs. the Agency
attempts to attain a level as close to the
MCLG as is feastble..For carcinogens."  •
EPA evaluates the cancer risk at various
contaminant levels in order to ensure
that the MCL adequately protects public
health. The Agency targets a reference
cancer risk range of 10"' to 10"* excess
individual risk from lifetime exposure
using conservative  models which are not
likely to underestimate the risk. Since
the underlying goal of the Safe Drinking
Water Act is to protect the public from
adverse health effects due to drinking
water contaminants. EPA seeks to
ensure that the health risks associated
with carcinogenic contaminants are not
significant.
  For most contaminants regulated
today. The PQL is identical to that
proposed in the July 1990 notice. In the
case of dioxin. EPA lowered the PQL
based upon a new MDL study using
Method  1613 (USEPA. 1990hJ. This study
Identifies an MDL of SxiO"'mg/l.
which is exactly twice as low as the
MDL of ixWrng/l that EPA identified
in the July 1990 proposal. EPA provided
this new information through the
November 29.1991  Notice of
Availability. Based on the new
information. EPA has decided to set the
                          PQL at five times the MDL or at 3x10"'
                          mg/1.
                            In the July 25.1990 proposed
                          regulation for dioxin [55 FR 30416). EPA
                          proposed to set the PQL (and MCL) at
                          five times the MDL. rather than ten
                          times the MDL because of concerns
                          about.the health risk-posed aUhe •••• ••"
                          concentration corresponding to ten
                          times the MDL. EPA recognized  that
                          some loss of analytic precision would
                          likely result from th'is, but believed it
                          was warranted by the additional health
                          protection that would be ensured by the
                          lower MCL In soliciting public comment
                          on the new dioxin analytic method
                          (1613) and MDL EPA asked for
                          comment on this same issue,  of whether
                          the additional health protection afforded
                          by a lower MCL warranted the likely
                          reduction in analytic precision. Several
                          commenters expressed concern about
                          likely reduction in analytic precision. In
                          using a multiplier of five rather than ten
                          in setting the  PQL (based on the  new
                          data), estimated lifetime cancer risks
                          would be reduced from 2.5X10"*. to
                          1.3x10"*. EPA believes this reduction in
                          risk is warranted, because it brings the
                          MCL closer to the 1 xlO~* target
                          maximum risk that EPA uses for
                          national primary drinking water
                          regulations. Also, as discussed above.
                          EPA believes that the degradation in
                          analytic precisional accuracy is not
                          unreasonable in going from 50 to 30 ppq.
                            EPA also calculated the annual
                          household costs for large systems to
 remove the SOC contaminants to or
 below the MCL using GAC. PTA or
 oxidation. As Table 18 shows, these
 costs are estimate to be generally about
 $20 per household per year for large
 systems to jnstall and operate any of
 these technologies. Cost estimate* have
 not changed frdm the estimates in the'
 proposal. No significant comments on
 unit treatment costs were submitted.
 EPA believes these costs are
 reasonable, as are the associated
 national costs as shown in the RIA. EPA
 therefore promulgates the MCLs at the
 levels listed in Table 18.
  Pursuant to SDWA section
 1412(b)(10). the effective date for all
 MCLs promulgated today (except  for the
 MCL for endrin) is 18 months after
 publication of today's notice (see the
 beginning of today's notice for the exact
 date). The effective date for the MCL for
 endrin is set at 30 days after publication
 of today's notice. The MCL for endrin
 promulgated today represents a
 relaxation of the existing MCL for
 endrin (from 0.0002 mg/1 to 0.002 mg/1).
 Even though SDWA section 1412(b)(10)
 calls for the effective date of MCLs to bt
 18 months after promulgation. EPA
 interprets this provision not to apply in
 the case of an existing MCL that is being
 revised to a higher level, since utilities
 do not need time to prepare to meet the
 revised level (they are, in-effect. already
 required to be meeting it).
                      TABLE 18—MCL ANALYSIS FOR CATEGORY I SYNTHETIC ORGANIC CONTAMINANTS
SOC contaminant

Ocnitxomctr.jrw „,,„ 	 _..„., 	
OitZ-ethytfiexytlpnthatate.... 	
HcxacftlcfobenzenG ,«....:.,„ 	 „ 	
Benzofajpyrene .«..«....».».«..^ 	 „ 	
2,3.7,8-TCOD™ 	 	 	

Final
MCLG '
(mg/l)
0
0
0
o
0

Final
MCL
(mg/l)
0.005
0.006
0,001
00002
3x10"»

10'«
risk -
(mg/l)
0,05
0.4
0.002
00002
2x 10"'

PQL
(mg/l)
0.005
0.006
0.001
00002
3x10'§

Annual h
cos
GAC

S20.00
20.00
2000
2000

ousanott
ts»
PTA
18.00




	
Notes





MCL it *t 1.3x 10M risK.

    1 EPA polcy is mat lot all Category I carcinogens me MCLG "» zoro.
    1 For large systems.
  (2) Category II and III contaminants.
For the Category II and III SOC
contaminants listed in Table 19, each of
the MCLs was proposed equal to its
proposed MCLG. Because the MCLGt
for di(2-ethylhexyl)adi-pate and
simazine have changed from the levels
proposed in July 1990, as discussed
above, the MCLs have also changed.
The MCL for-di(2-ethylhexyl)adipate
changed from 0.5 to 0.4 mg/l and the
MCL for simazine changed from 0.001 to
0.004 mg/L The MCL for 1.2.4-
trichlorobenzene changed from 0.009 to
                         0.07 mg/l. Both of these changed MCLs
                         are equal to the final MCLGs. which
                         were revised based on a reassessment
                         of the health data as discussed above.
                           Section 1412 of the S,DWA requires
                         EPA to set MCLs as close to the MCLGs
                         as is feasible (taking costs into
                         consideration). EPA believes that it is
                         feasible to set the MCL* at the MCLGs
                         for the Category II and Category III
                         contaminants because (1) the PQL for
                         each contaminant is at or below the
                         level established by the MCLG: (2) BAT
                         can remove each contaminant to a level
equal to or below the MCLG: and (3) the
annual household cost to install BAT in
large systems is reasonable. Final
estimated costs are the same as were
established for the proposal. EPA
believes that these costs are affordable
for large systems. EPA also believes the
associated national costs, as shown in
the RIA, are reasonable. Therefore. EPA
promulgates the MCL* for the non-
carcinogenic contaminants equal 10 their
MCLG*.

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                       I

             Federal Raster / Vol.  87. No. 138 / Friday. July 17. 1992 / Rules and Regulations
                                                                                                          31B1
                 TABLE 19.—MCL ANALYSIS FOR CATEGORY II AND III SYNTHETIC ORGANIC CONTAMINANTS
5OC contaminant
Dal&pon ..«.
Ort2-ftttryHHcy)aflip3H' ... - 	 — . .. . .
QtnoSffO 	 • 	 •• 	
DtQudt 	 	 	 , 	 	 	 	 	 :. 	
£ndothafl 	 	 	 	 	 - 	
Enflfin
Glypfiosate 	 ..— 	 	 	 .
HexacMofocydopefitadiene 	 	
Oxamyf (Vydate)..., 	 	 	 	 	 , 	 	 	
Pictofafn ,„ 	 	 	 	 	
Simazine 	 	 	
1 2 4-TrtcniOfOt>Gn20O6 	 — 	 • 	 	 	
1 1 2-Tncntofoeihana 	 	 	 	 	

! Final
;. MCLG
| (fftg/l)
I 02
-- , , ,,,( 0*
. ; 0007
	 : 002
1 01
1 0002
: o 7
i 005
0 2
	 • 05
i 0004
	 j 0 07
. . .. • 0003
I
Final '
MCL
(mg/l) j
02 I
04 I
0.007
0.02 :
01
0002 '
0.7 '
005 j
02
OS :
0.004 !
0.07 |
0005 (
POL
(rrg/l)
001
0.005-
0002
0.004
009
0001
0.4
0001
005
0.002
0001
0005
0.005
Annual household costs
BAT '
GAC i PTA !
$3500
25.00
20.00
25.00
' 3500
2000
20.00
25.00
35.00
2000
20.00
25.00
|
S1700|
'" 	 1
	 1
£1 Sfl
1.7 00 :

1700 !
42.00 ;
uung
OX
V
-900
   1 For iarg« systems.
C. Compliance Monitoring
Requirements

1. Introduction

  The proposed compliance monitoring
requirements (55 FR 30427} included
specific monitoring requirements for
inorganic contaminants (IOC*), volatile
organic contaminants (VOCs); and non-
volatile synthetic organic chemical*
(SOCa). EPA proposed that all
community and non-transient non-
community water systems comply with
the monitoring requirements for all
contaminants. EPA also requested
comment on whether the MCL for
sulfate and the associated monitoring
requirements should apply to  transient.
non-community system since  this
contaminant is associated with acute
effects. The compliance monitoring
requirements promulgated in today's
rule apply to all community and non-
transient non-community water systems.
The compliance monitoring
requirements that EPA is promulgating
today are the minimum currently
necessary to determine whether a public
water supply delivers drinking water
that meets the MCL*.
  The  proposed compliance monitoring
requirements for the contaminants in the
July 25.1990 notice were similar to the
monitoring requirement* proposed in a
May 1989 notice [54 FR 22124] for 38
inorganic and synthetic organic
contaminants. In the July 1990 proposal
{55 FR 30428), EPA explained  that the
Agency's goal in promulgated
compliance monitoring requirement* is
to standardize the requirement* and to
synchronize the schedules to minimize
overall sample collection.and analysis  .
efforts. In keeping to that goal, the
Agency further stated in that  notice [55
FR 30429] that change* to the monitoring
requirement* in the final rule  to the May
1989 proposal would likely  effect the
final requirements for the contaminants
in today's notice.
  EPA promulgated final regulations for
the contaminants in the May, 1989
proposed rule on January 30,1991 and
July 1.1991 [56 FR 3528 and 56 FR 30266,
respectively]. In the January 1991 final
rule. EPA described a standard
monitoring framework that was
developed by the Agency based on the
proposed monitoring requirements and
on the comments received by EPA in
response to the May 1989 notice. The
final rule, and the November 1991. NOA
concerning today's rule, indicated that
EPA intends to apply this framework to
future requirements for source-related
contamination (i.e., inorganics, VOCs,
SOCs and radionuclides), as
appropriate. The framework and how it
applies to today's rule is described in
more detail below.
  The contaminants in today's rule
usually occur at limited frequencies.
thereby justifying flexible monitoring
requirements. In general, the possible
occurrence of these contaminants in
drinking water may be predictable to
some extent based upon a multiplicity of
factors such as geological condition*,
use patterns (e.g., pesticides), presence
of industrial activity in the area, type of
source or historic record. Therefore. EPA
believes that State* should be allowed
the discretion to increase or decrease
monitoring based on established criteria
and site-specific conditions. A* part of .
today's rule EPA is withdrawing these
contaminants from the unregulated
contaminant monitoring requirement* of
§ 141.40 since they will now be
monitored as regulated contaminant*
under J i 141.23 and 141.24.
  In developing th« compliance
monitoring requirement* for these
contaminant*. EPA, considered:
  (1) Tb« likely lource of drinking water
contaminant*.
  .(2) The nature of the potential adverse
 health effects, i.e.. chronic versus acute
 effects.
   (3) Differences between ground and
 surface water systems.
   (4) How to collect samples that are
 representative of consumer exposure,
   (5) Sample collection and analysis
. costs,
   (6) The use of historical monitoring
 data to identify vulnerable systems.
   (7) The limited occurrence of some
 contaminants, and
   (8) The need for States to tailor
 monitoring requirements to system- and
 area-specific conditions.
   EPA monitoring requirements are
 designed to ens>'re that compliance with
 the MCLs is met and to efficiently utilize
 State and utility resources. EPA's goal in
 today's rule is to ensure these
 monitoring requirements are consistent
 with monitoring requirements
 promulgated previously by EPA and
 with known occurrence trends. The
 monitoring requirements promulgated
 today focus monitoring in individual
 public water systems on the
 contaminants that are likely to occur, an
 approach that includes:
   •  Allowing States to reduce
 monitoring frequencies based upon
 system vulnerability assessments for the
 organic chemicals listed in S 141.61 (a)
 and (c),
   •  Allowing States to target monitoring
 to those system* that are vulnerable to a
 particular .contaminant.
   •  Allowing the use of recent
 monitoring data in lieu of new data if
 the system has conducted a monitoring
 program generally consistent with
 today's requirement* and using reliable
 analytical method*.
   •  Encouraging the States to use
 historical monitoring data meeting
 specific quality requirement* and other

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 31818
      '    ' '          *         ''          •  ••  i  .      ...     .             .

Federal  Regular / Vol. 57. No.  138 / Friday.  July 17. 1992 / Rules and Regulations
 available records to make decisions
 regarding a system's vulnerability.
   • Requiring all systems to conduct
 repeat monitoring unless they
 demonstrate through an assessment or
 other data that they are not vulnerable.
   • Designating sampling locations and
 frequencies,that permit simultaneous..
 monitoring for all regulated source-
 related contaminants, whenever
 possible.
   • Phase-in monitoring requirements
 based on system size. For systems with
 150 or more service connections.
 mcn:lor:ng begins in the first compliance
 period (January 1.1993 to December 31.
 1995). For those systems wi.th less than
 150 service connections, monitoring
 begins in the second compliance period,
 (January 1.1996 to December 31.1998).
   Although base monitoring
 requirements for surface and
 groundwater systems are the same for
 all contaminants, groundwater systems
 will qualify more frequently for reduced
 monitoring and return more quickly to
 the base monitoring requirements
 because (1) the sources and mechanisms
 of contamination for ground and surface
 water systems are different. (2) the
 overall quality of surface waters tends
 to change more rapidly with time than
 does the quality of ground waters, and
 (3) seasonal variations tend to affect
 surface  waters more than ground
 waters.  Spatial variations are more
 important in ground waters than in
 surface  waters since groundwater
 contamination can be a localized
 problem confined to one or several wells
 within a system. Therefore, monitoring
 frequency is an important factor to
 determine baseline conditions for
 surface  water systems, while sampling
 location within the system generally is
 more important for groundwater
 systems. Today's monitoring
 requirements generally require surface
 water systems to monitor at an
 increased frequency for longer periods
 than groundwater systems.
 2. Effective Date
  In the July 25.1990 Federal Register
 Notice. EPA proposed to allow an
 additional 12 months after the effective
 date of the  rule taking final action on the
 proposal for public water systems to
 complete the first round of sampling and
 analysis and to report the results of such
 monitoring  to the States. The effective
 date of the  rules is by statute, 18 months
 from promulgation. EPA also proposed
 to allow an additional 12 months after
 the effective date of the final regulations
 for the States to complete vulnerability
assessments.
  Most commenter*  supported
extending the initial monitoring and
                          reporting period as well as the date to
                          complete vulnerability assessments.
                          They claimed that the 18 months
                          compliance schedule is too rigorous.
                          especially since extensive investigation
                          is required. Some commenters claimed
                          there is a lack of laboratory capacity for
                          conducting analyses using- the new - . •
                          analytical methods and a lack of
                          qualified staff as a rationale for
                          extending the first.round of monitoring
                          and the reporting of the results of such
                          monitoring to the States. Other
                          commenters cited the impact on State
                          resources to properly notify water
                          systems regarding the new monitoring
                          requirements, develop .the necessary
                          guidance and procedures, train staff, to
                          review vulernability assessments.
                          reduced monitoring decisions, etc.. and
                          to be prepared to administratively
                          handle the data  generated, as the
                          rationale for allowing States sufficient
                          time to initiate the monitoring
                         requirements. One commenter suggested
                          that small systems be given more time to
                         comply with the requirements because
                         of the cost burden on these systems.
                         Another commenter suggested that the
                         systems should be allowed to submit to
                         the State their own schedule for
                         compliance for State approval.
                           In the November 29.1991 NOA. EPA
                        .stated that it was considering requiring
                         that monitoring begin during the first
                         compliance period following
                         promulgation. This change would
                         synchronize the  monitoring schedule for
                         the 23 contaminants with those
                         promulgated for  other SOCs and lOCs in
                         the January 30.1991 notice. Two
                         commenters supported this change.  ,
                         However. 14 commenters disagreed with
                         the change since they felt it effectively
                         moved monitoring up three years from
                         what was proposed, there would be a
                         lack of time to conduct vulnerability
                         assessments, inadequate time for
                         laboratories to become certified, and
                         increased cost to States and public
                         water systems.
                           EPA agrees with the commenters that
                         problems may occur in the early stages
                         of implementing  the monitoring
                         requirements. These problems are
                         alleviated to some extent, however, by
                         the fact that this  rulemaking is adopting
                         the Agency's Standard Monitoring
                         Framework (which EPA originally
                         adopted in the January,30.1991 rule
                         setting regulations for 33 contaminants).
                       _and is adopting a phased approach for
                         initial monitoring. Specifically, the
                         Agency has decided to require that
                         monitoring for the contaminants  in
                         today's rule b« completed (1) during the
                         first compliance period, as specified in
                         the-Standard Monitoring Framework.
                         which begins January 1.1993 and end*
  December 31.1995 for systems with 150
  or more service connections, and (2)
  during the period beginning January 1.
  1996 and ending December 31.1998 for
  systems with fewer than 150
  connections. In addition, all
  vulnerability assessment decisions must
  be completed prior to' the calendar year
  when the initial monitoring must be
  completed. Laboratories can be granted
  provisional certification to perform
  analyses for the contaminants in today's
 . rule  during the 1993-1995 compliance
  period. See the discussion under
  Laboratory Certification. •
   EPA believes this  phased-ih time
  frame allows adequate time  for
  implementation of the monitoring
  requirements since for larger systems it .
  provides for more than two additional
  years after the effective date of today's
  rule for completion of the first round of
  sampling and analysis and for small
  systems it provides three years
  additional time. This monitoring
 schedule also coincides  with the
  sampling and analysis schedule for 38.
 contaminants previously regulated (56
 FR 3526 and 56 FR 30266|. By allowing
 systems with less than 150 service
 connections to begin initial monitoring
 in the second compliance period
 (January 1.1996 to December 31.1998).
 more time is allowed for States.
 laboratories, and small systems to be
 fully prepared (i.e.. conduct vulnerability
 assessments, find funding).
  EPA believes that the earlier 1993-
 1995 compliance period for those
 systems with 150 ormore service
 connections is appropriate, to better
 protect health. These systems would
 have  been required to begin monitoring
 for these contaminants under
 unregulated monitoring requirements of
 the January 30.1991 rule. Since many of
 the previously unregulated
 contaminants are contaminants being
 regulated in today's rule, the Agency
 believes the 1993 monitoring will result
 in only minor increased monitoring
 impact. Those individual contaminants
 moving from "unregulated" to
 "regulated" status are being deleted
 from the unregulated  contaminant
 monitoring requirement*.
  States have the discretion, and may
 well choose, to require a percentage
 (e.g., one-third) of the required systems
 to monitor during each year of the three-
 year compliance period States have the
 option to prioritize monitoring based on
 system size. EPA ha*  decided not to
allow systems to submit their own
monitoring schedule for State approval
as some commenters suggested. EPA
believes States need to control the flow
of samples and data to them in order to

-------
               rnoay. puy
                                                                                        ana- «ggmanon«
          orderly implementation and
   enforcement, within the regulatory
   requirements and avoid undue
   administrative burdens and potentially
   unmanageable enforcement problems.

   3. Standard Monitoring Framework
     In response to the May 1989 notice
   covering a different set of contaminants.
   EPA received extensive comment*-;
   stating that the proposed monitoring
   requirements were complex and would
   lead to confusion and misunderstanding
   among the public, water utilities, and
   State personnel. Commenters also cited
   the lack of coordination among various
   regulations. Many commenters
   suggested that EPA simplify, coordinate.
   and synchronize the proposed regulation
   with previous regulations. In response to
   these comments. EPA developed a
   Standard Monitoring Framework to
   reduce the complexity of the monitoring
   requirements, coordinate the
   requirements among various regulations.
   and synchronize the monitoring
   schedules. This framework is discussed
   extensively in the January 30.1991 final
   rulemaking to the May 1989 Notice [56
   FR 3560]. The Agency also indicated
   that this framework will serve as a guide
   for future source-related monitoring
   requirements. The framework was
   developed based on the proposed
   requirements, the options and requests
   for comments EPA discussed in the
   proposal, and the comments received by
   EPA.
     The use of a Standard Monitoring
   Framework for the contaminants in
   today's rule was supported by many of
   the comments received. Commenters
   cited the efficient use of resources as the
   major reason to synchronize the
   monitoring requirements.
      EPA believes  that using a Standard
   Monitoring Framework satisfies the
   comments that recommended reducing
   the complexity of the requirements,
   synchronizing monitoring schedules.
   standardizing regulatory requirements.
   and giving regulatory flexibility to
    States and systems to manage
    monitoring programs. EPA believes
    these changes will reduce costs by
    combining monitoring requirements tor
    the contaminants regulated by the
    January 30.1991 rule and today's rule
    (i.e.. the presence of multiple
    contaminants can be evaluated in a
    single laboratory sample and analysis.
    or by a single vulnerability assessment)
    and will promote greater voluntary
    compliance by simplified and
'   standardized monitoring requirement*.
v.      Use of the framework envisions a   •
    cooperative effort between EPA and
    States. The monitoring requirement*
    promulgated today are the minimum -   •
fede<*al requirements necessaiy to
ascertain systems' compliance with the
MCLs. In some canes. States will
increase the monitoring frequencies
beyond the federal minimums to address
site-specific conditions.
  For all contaminants contained in
today's rule, minimum (or base)
monitoring requirements requirements
may be1 increased or decreased by
States- based upon prior analytical
results and/or the results of a
vulnerability assessment. The
monitoring requirements outlined today
follow to a large extent the requirements
proposed on July 25.1990. In the July
1990 proposal EPA stated as  a goal to
efficiently utilize State and utility
resources and be consistent with
monitoring requirements previously
promulgated by EPA. EPA believes that
today's requirements meet that goal.
  a. Three-, six-, nine-year cycles. In
order to standardize the monitoring
schedule  for different regulations. EPA
has established nine-year compliance
cycles. Each nine-year compliance cycle
consists of 3 three-year compliance
periods. All compliance cycles and
periods run on a calendar year basis
(i.e.. January 1 to December 31). The
January 30.1991 rule established the
first nine-year compliance cycle
beginning January 1.1993 and ending
December 31.2001: the second cycle
beginning January 1.2002 and ending
December 31.201ft etc. Within the first
nine-year compliance cycle (1993 to
2001), the first compliance period begins
January 1,1993 and ends December 31.
1995; the  second begins January 1.1998
and ends December 31.1998;  and the
third begins January 1.1999 and ends
December 31. 2001..
  In the January 1991 Notice. EPA
required that  initial monitoring (which
was defined as  the first full three-year
compliance period beginning 18 months
after the promulgation date of a rule)
must begin in the First full compliance
period after the effective date of the
final rule. EPA solicited comments on
this issue in the November 29.1991 NOA
and is modifying initial monitoring, as
described above. For today's regulation.
the effective date is January 17.1994.
The next full three-year compliance
period after this effective date begins
January 1.1996. After reviewing
comments received, the Agency has
decided that systems serving 150 or
more service connections must conduct
initial monitoring during the January 1,
1993 to December 31.1996 period and
those serving less than 150 service
connections must conduct initial •
monitoring'during the January 1.1998 to
December 31.199(5 period. EPA believes
the phase-in of monitoring based on
 system size will increase public health
 protection to the public by identifying
 noncompliance earlier for larger systen
 which serve a large fraction of the
 population (and which would have bee;
 required to monitor these contaminants
 in any event under the "unregulated
 contaminant" requirements of the
 January 1991 rule). At the same.time..th
 phase-in will allow States, small
 systems, and laboratories more time to
 effectively implement today's rule for
 small systems. EPA believes  this is an
 appropriate balancing of the  need to
 identify noncomplying systems through
 monitoring, and the implementation
 burden on States and laboratories. This
 change would synchronize the
 monitoring schedule for the 23
 contaminants in this rule with those
 promulgated for other SOCs and lOCsit
 the January 30.1991 notice.
  Under the July 1990 proposal,
 monitoring for the contaminants in this
 rulemaking would have been required to
 be initiated no later than November 199C-
 (i.e.. the effective date of this
 rulemaking). EPA does not believe that
 changing the initial monitoring schedule
 to begin January 1993 instead of
 November 1993 for systems with .150 or
 more service connections will
 significantly affect costs for those
 systems. Under this schedule. States
 must establish an enforceable
 monitoring schedule for each system
 during the initial three-year compliance
 period. States have the  discretion to
 schedule systems by size, vulnerability.
 geographic location, laboratory access.
 or by other factors. In some cases
• systems will not need to conduct
 monitoring until the latter part of the
 first three-year period, rather than
 needing to start monitoring immediately
 as of January 1993 (see  discussion of the
 Standard Monitoring Framework at 56
 FR 3560). In addition. EPA  believes there
 will be a decrease in costs due to the
 effects of synchronizing, the monitoring
 requirements in this rule with those of
 earlier rules—e.g.. there will be a cost
 savings resulting from a system's ability
 to evaluate the presence of multiple
 contaminants with the analysis of a
 single sample, and to perform
 vulnerability assessments covering
 multiple contaminants.
  Several commenters believed that
 States would be unable to  develop
 adequate certified laboratory capacity
 in order to monitor during the 1993-199S
 period. EPA has responded to this
 concern by encouraging provisional
 certification of laboratories. «*
 discussed above.
  b. Base monitoring requirements. In
 order to standardize lh« monitoring

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31*2*
, grMal3«V
                                                                      VSOL
                                             sad
reqtdreaenti. EPA ka« established base
(or minimum) monitoring frequencies for
all systems at each sampling point
These bate monitoring frequencies
apply to all community and noa-
transient water systems, la cases of
detection or non-compliance. EPA has
specified increased monitoring
frequencies from the base, The*e  ,.
increases are explained below. Systems
will also be able to decrease monitoring
frequencies from the base requirements
by obtaining waivers from the State
where a State permits such waivers.
Decreases from base monitoring
requirements through waivers are
discussed in general under the section
on decreased monitoring and in the
discussion of monitoring frequency for
each class of contaminants.
  In most cases, these Increased or
decreased frequencies are similar to the
frequencies proposed in July 1990.
Specific changes are discussed below
under each contaminant group.
  Inorganic contaminant base
requirements are the same as
proposed—one sample at each sampling
point every three years for groundwater
systems and annually for  surface water
systems. Modification of base
requirements for VOCs is discussed
below in the section on VOC monitoring
frequency.
  For the non-volatile synthetic organic
compounds (SOCs).  EPA proposed that
monitoring was not  required unless the
State determined that the system was
vulnerable based upon a State-
conducted assessment. EPA requested
comment on the appropriate time frame
for completing these assessments. If die
State determined that a system was
vnlerable to these SOCs, systems would
be required to monitor on a three- or
five-year schedule depending upon
system size and whether contaminants
were detected.
  The July 1990 notice also mduded an
alternative monitoring scheme which
would require all CWSs and non-
transient, non-community water systems
(NCWSs) to monitor for the non-volatile
SOCs at specified (base) frequencies.
Most comments EPA received opposed a
round of initial mora'toring-by all
systems. These commenteis cited the
lack of occurrence of these
contaminants in drinking  water and the
expense of monitoring. Several
commeaters questioned the availability
of sufficient laboratory capacity.
   After reviewing and evaluating the
comments on saonitorfcig for the SOCs ia
the May 1998 Notice, EPA adopted en
alternative saooitorfag approach which
requires systems to  monitor it specified
base frequencies imless the
requiremesrts are warred  (eftber redaced
or eliminated) by tne State. The rei
for this change are given in the January
1991 rule (56 FR 3S60J. In summary, the
requirement that all systems .monitor for
these contaminants is more protective of
health than were the proposed
requirements because systems will be
required to monitor if the State does not
conduct a.vulnerability assessment, or,.
does not approve a vulnerability
assessment conducted by the system.
The result of this change is that mere
will always be an enforceable
requirement in the absence of a State
waiver.
  In today's rule EPA is adopting the
same monitoring approach for the SOCs.
EPA believes that the cost impact of this
approach  is the same as under the
proposed  scheme provided a
.vulnerability assessment is conducted
and a waiver is granted.
  EPA has combined the above '
with the provision  that public water
systems may conduct meir own
vulnerability assessments and, at me
State's discretion, may obtain s waiver
if they are determined not to be
vulnerable (see waiver discussion
below}. EPA has shifted the
responsibility  to conduct vulnerability
assessments from States to systems
because tne vulnerability assessment is
a monitoring activity that historically
has been a system responsibility. Each
individual system can decide whether to
conduct a vulnerability assessment
(rather than simpty going right to
monitoring) based on cost, previous
monitoring history, and coordinatian
with other vulnerability type
assessments (Le_ sanitary  surveys.
Wellhead Protection Assessments}. In
addition, because of States' Indicated
resource shortfalls, many States might
not ccndact vulnerability assessments.
Thougn EPA is permitting systems to
conduct vulnerability ai•«?laments.
approval of waivers based on those
vulnerability assessments rests with tto
States. EPA believes the changes
outlined above address, in part, the
State resource issue and will result in
adequate  monitoring and enforceable
drinking water standards.
  Based on limited occurrenca data.
EPA anticipates that most system*
would qualify for a waiver from
monitoring tor most SOCs in today's
rule, m cases where a system is not
granted a waiver by the State, it wul be
reqvtred to monitor at the specified base
frequency. In SOB. for the reasons
specified above, all system wiH tw
required to monitor for all SOCs with an
opportunity for reduced monitoring
based wpoci a vulnerability i
                                       monitoring re
                                                              i for all VOCs,
                                       EPA promulgated on fuly 1. 199t
                                       modifications to the monitoring
                                       requirements for me 18 VOCs in two
                                       previous rules (}uiy fi, 1987 and January
                                       30. 1991 Federal Register Notices), The
                                       comments submitted to EPA during the
                                       comment period for the January 1991
                                       notice reveated-support for •.-'••   ...
                                       synchronization of the monitoring
                                       requirements and schedules. Therefore.
                                       the monitoring requirements in today's
                                       rule are identical to the requirements for
                                       these previously regulated VOCs [56 FR
                                       39267J.
                                        d. Increased monitoring.  In general.
                                       today's rule requires monitoring
                                       frequencies to increase when a
                                       contaminant is measured at a certain
                                       concentration. These concentrations are
                                       specified in each rule, and vary by class
                                       or toxicity of the contaminant. la today's
                                       rule, consistent  with the monitoring
                                       requirements set forth in the January
                                       1991 rule for other inorganic
                                       contaminants. VOCs. and SOCs. these
                                       "trigger" concentrations are set at (1)
                                       the MCL* for the inorganic
                                       contaminants: and (2) the analytical
                                       detection limits  for VOCs and SOCs.
                                      The detection limit for each VOC is
                                      0.0005 mg/1. The SOC detection limits
                                       are the method detection limits given in
                                      Table 14 and { 14L24(i)(ia). The
                                       rationale for varying the detection limits
                                                  monitoring is  addressed in
     l«pona
  c. Votctilt Organic Chemical*
(VOCtf. fa orde? to standardize tfe '
                                        each section for the contaminant
                                        monitoring frequencies below (also see
                                        the January 1391 rule, 56 FR 3560-66).
                                          After exceeding toe trigger
                                        concentration for each contaminant.
                                        systems raust immediately increase
                                        monitoring to quarterly (beginning in the
                                        subsequent quarter after detection) to
                                        establish a baseline of analytical results.
                                        Groundwater systems are required to
                                        take a mmtmnra of two samples and
                                        surface water systems must take four
                                        samples before the State may permit
                                        less frequent monitoring. EPA a
                                        requiring surface water systems to take
                                        a minimum of four tanp^es (rather than
                                        the two samples required for
                                        groundwater systems) because .surf ace
                                        water is generally more variable man
                                        ground waiter and. consequently.
                                        additional sampUmj is required to
                                        determine that th« system « "reliably
                                        and consistently" below the MCL.
                                        Today's rale allows a State, after a
                                        baseline is established, to reduce the
                                        quarterly mooitoring frequency if the
                                        system is "rettabiy and consistently"
                                        betow dae MCL. "Reliably and
                                        consistently" sneans that the State has
                                        enough ccofideoce list fctare sampling
                                        result* w(E b« svfocieatrjr below the
                                        MCL to justify reducing the quarterly

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             Federal Register / Vol.  57. No. 138  /  Friday, July 17.  1992 / Rules and Regulations
                                                                      322
monitoring frequency. At a minimum, all
individual samples should be below the
MCL. Systems with widely varying
analytical results or analytical results
that are just below the MCL would not
meet this criterion. In all cases, the
system remains on a quarterly sampling
frequency until the State determines  that
the system is."reliably.and consistently"-
below the MCL. EPA is adopting this
approach based on comments received
on the May 1989 and July 1990 proposed
rules that suggested the EPA allow
States to modify the monitoring
schedules in those systems which are
less than the MCL. EPA believes this
approach will result in consistency
among the regulatory requirements for
the different classes of contaminants.
.  In the July 1990 proposal. EPA
requested comment on whether EPA
should reduce the three year quarterly
monitoring requirement to one year of
quarterly monitoring in situations where
initial monitoring shows particularly low
levels of detection relative to the levels
of concern (i.e., MCLs) or in situations
where cleanup activities have resulted
in low levels of detection. Several
commenters indicated that a minimum
of 12 quarters after monitoring had been
increased by a trigger level was too long
and supported a reduction in the
monitoring requirements in cases such
as these. These commenters suggested
that EPA should require sufficient
monitoring to establish a baseline. In the
January 1991 Notice EPA prescribed a
minimum of two samples for
groundwater systems and four samples
for surface water systems to establish a
baseline. EPA is adopting the same
approach today because the Agency
agrees with commenters who pointed
out that systems whose analytical
results remain below the MCL do not
pose a health threat.
   In the July 1990 proposal, the Agency
proposed to reduce the repeat
monitoring requirements when a
contaminant is consistently-detected at
less than 50 percent of the MCL Many
commenters objected to this trigger,
stating that it was "arbitrary". The
Agency modified this requirement in the
January 1991 notice with respect to other
contaminants to give States additional
flexibility to reduce monitoring for those
systems whose analytical results are
"reliably and consistently less than the
MCL" (see 5 § 141.23(c)(8).
141.24(f)(ll)(ii) and 141.24(h)(7)(ii)  50 FR
3560-68. 3580, 3584. 3588). EPA has
decided that systems meeting this
criteria are also eligible for reductions
from the increased monitoring frequency
requirements for the contaminants in
 today's rule.
  e. Decreased monitoring. Systems
may decrease monitoring from the base
requirement by receiving a waiver from
the State. State waivers may either
eliminate the monitoring requirement for
that compliance period (for SOCs) or
reduce the frequency (for inorganics and
VOCs). Waivers are either based on a
review-of established criteria ("a waiver
by rule") or by a vulnerability
assessment.
  A "waiver by rule" is based simply on
meeting certain criteria set out in EPA
regulations and based, for example, on
previously collected analytical results.
For example. 5 141.23(c) (originally
adopted in the January 1991 notice and.
by this notice, applicable to the
contaminants in today's rule) specifies
that States may grant "waivers by rule"
to systems for five inorganic
contaminants. The waivers are effective
for  up to nine years (or one compliance
cycle). In order to qualify for a waiver,  a
system must have a minimum of three
previous samples  (including one taken
after January 1.1990) with all analytical
results below the MCL The State must
consider a variety of issues in making a
"waiver by rule" determination, such as:
(1) Reported concentrations from all
previous monitoring,  (2) degree of
variation in reported concentrations,
and (3) other factors which may affect
contaminant concentrations such as
groundwater pumping rates, changes in
the system's configuration, changes in
the system's operating procedures, or
changes in stream flows or
characteristics.
  A "waiver by vulnerability
assessment" may take one of two forms.
The first involves a determination as to
.whether a given contaminant which
does not occur naturally is or was used,
manufactured, and/or stored in an area
nearby the system. If the contaminant is
not used, manufactured, and/or stored
nearby, the system can receive a "use
waiver." Second, if a "use waiver"
cannot be granted, a system may
conduct a thorough assessment of the
water source to determine the system's
susceptibility to contamination.
Susceptibility considers: (1) Prior
analytical and/or vulnerability
assessment result!!, (2) environmetai
persistence and transport (3) how well
the source is protected. (4) wellhead
protection program reports, and (5)
elevated nitrate levels. Systems with no
known susceptibility to contamination
(based upon an assessment of the above
factors) may be granted a "susceptibility
waiver."
  All waivers must be granted on a
containinant-by-contaminant basis.
However, systems and States will find  it
 economical to apply for and grant the
 waiver for those contaminants that may
 be analyzed using the same analytical
 methods. This packaging of assessment:
 and State decision making will yield  *
 significant cost savings to both systems
 and State primacy programs.
   Waivers for the SOCs and VOCs.may
" be granted after the system conducts a.
 vulnerability assessment and the State
 determines the system is not vulnerable
 based on that assessment. A waiver
 must be renewed during each
 compliance period. Waivers for
 inorganic contaminants may be granted
 for up to nine years. If a system does not
 receive a waiver by the beginning of the
 year in which it is scheduled to monitor.
 it must complete the base monitoring  .
 requirement.
   One change that EPA is adopting in
 5 142.92 is that EPA may rescind
 waivers issued by a State where the
 Agency determines that the State has
 issued a significant number of
 inappropriate waivers. EPA does not
 intend to utilize this provision except in
 special situations where the State has.
 not followed its own established and
 EPA-approved protocols and procedures
 • (see also the discussion on State
 primacy requirements).  If a waiver is
 resinded. the system must monitor in
 accordance with the base requirements
 in today's rule.
   f. Vulnerability assessments. EPA
 received numerous comments on the
 .issue of vulnerability assessments. In
 the  July 1990 Notice. EPA requested
 comment on several alternatives for the
 process of making vulnerability
 decisions. One option involved requiring
 States to assess the overall
 hydrogeological vulnerability of each
 water source supplying  a PWS instead
 of making contaminant-specific
 determinations for each contaminant at
 each PWS. Another option was to
 assess the overall use of each
 contaminant within specific regions,
 focusing on potential  sources of
 contamination within a  defined region.
 EPA also requested comment on
 whether systems should be required to
 monitor for all contaminants that are
 subject to the same analytical technique.
 EPA proposed to allow  States to
 conduct area-wide assessments (based
 on contaminant use information) or one
 assessment of the water source
 susceptibility to contamination (based
 on hydrogeological information).
   Commenters generally supported the
 use of vulnerability assessments  as a
 first step in lieu of requiring all systems
 to monitor. Different opinion! were
 expressed regarding how to conduct
 these assessments.

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 11122
Fedni
/ VoL  57. No. 138  /  Friday. July 17. laaz / Rulea tad RegaUtkra
   Some cootmenter* Indicated mat EPA
 should provide detailed guidelines that
 State* would use to make vulnerability
 determinations. Example* cited included
 the development of environmental fate
 dccuments. identification and
 characterization of the available sources
 of information regarding the presence of
 contaminants, and disposal facilities-  " '
 that nay impact water sources, among
 others. Other commenters questioned
 whether State agencies would have
 sufficient financial and human resources
 to collect the necessary information to
 conduct an assessment of a water
 system's vulnerability.
   EPA has decided that a detailed
 protocol for what is usually a very site-
 specific analysis is not appropriate.
 Instead. EPA desires that each State
 develop its own specific vulnerability
 assessment procedures that use the
 general guidelines established by EPA.
 The Agency believes that the States are
 in the best position to develop detailed
 protocols. If a State chooses not to
 develop these procedures, systems
 cannot receive waivers and must
 monitor at the base requirements.
  In the proposal EPA listed the
 following criteria systems must consider
 in conducting vulnerability assessments
 for SOCs: Previous analytical results;
 proximity of the system to sources of
 contamination; environmental
 persistence: protection of the water
 source; and nitrate levels as an indicator
 of potential contamination by pesticides.
 For VOCs. the criteria were previous
 monitoring results, number of people
served, proximity to a large system.
proximity to commercial or industrial
 use.  storage or disposal of VOCs, and
 protection of the water source.
  EPA received comments OQ the
 process of how to make vulnerability
 decisions. Comments ranged from
 allowing the use of area-wide
 assessment to contaminant-specific
 assessment for individual supplies. One
 commenter suggested combining two
 options proposed (assessing the overall
 hydrological vulnerability of the water
 supplies and assessing the overall
 contaminant use). EPA agrees with this
 comment and. as part of tie earlier
 rulemaking for 36 contaminants, has
 made several changes to the
 vulnerability assessment criteria and the
 process to simplify the procedure {56 FR
 3562]. Today's rule also adopts  these
 changes. First, a two-step waiver
 procedure is available to all systems.
 Step *1 determines whether the
 contaminant that does not occur
 naturally is or WAS used, manufactured
 stored, transported, or disposed of in the
 area. In the case of some contaminants
                          an assessment of the contaminant's use
                          in the treatment or distribution of water
                          may also be required. "Area" is defined
                          as the watershed area for a surface
                          water system or the zone of influence
                          for a groundwater system and includes
                          effects in the distribution system.
                            If the State determines that the
                          contaminant was not-used.
                          manufactured, stored, transported, or
                          disposed of in the area, then the system
                          may obtain a "use" waiver. If the State
                          cannot make this determination, a
                          system may  not receive a "use" waiver
                          but may receive a "susceptibility"
                          waiver, discussed below. Systems
                          receiving a "use" waiver are not
                          required to continue on to Step «2 to
                          determine susceptibility. EPA
                          anticipates that obtaining a "use"
                          waiver will apply mostly to the SOCs
                          where use can be determined more
                          easily than for VOCs. Obtaining a "use"
                          waiver for the VOO will be limited
                          because VOCs are used extensively in
                          the United States. If a "use1' waiver
                          cannot be given, a system may conduct
                          an assessment to determine
                          susceptibility. Step *2.
                            Susceptibility considers prior
                          occurrence and/or vulnerability
                          assessment results, environmental
                          persistence and transport of the
                          chemical the extent of soorce
                          protection, and Wellhead Protection
                          Program reports. Systems witfc no
                          known "susceptibility" to contamination
                          based upon an assessment of me above
                          criteria may be granted a waiver by the
                          State. If "susceptibility" cannot be
                          determined, a system is not eligible for a
                          waiver. A system must receive a waiver
                          by the beginning of the calendar year in
                          which it is scheduled to begin
                          monitoring.
                           Several comroecters requested that
                          EPA permit "area wide" or geographical
                          vulnerability assessment
                          determinations. Though EPA at this time
                          is skeptical that "area wide"
                          determinations can be conducted wira
                          sufficient specificity to predict
                          contamination over a large area, the
                          final rule allows this option when State*
                          submit their procedure* for conducting
                          vulnerability assessments to determine
                          "use" waivers.
                           EPA's goal is to combine vulnerability
                          assessment activities in other drinking
                          water programs with today's
                          requirements to create efficiencies. EPA
                          also desires to use the results of other
                          regulatory program requirements, sndj
                          as Wellhead Protection Assessments, to
                          determine a system's vulnerability to
                          contamination. Systems and States may
                          schedule today's assessments with
                          sanitary surveys required under the
                                               Total Cdiform Rule {54 FR 27546J
                                               watershed-assessments, and othei' water
                                               quality inspections so that ail
                                               regulatory, operational, and managerial
                                               objectives are met at the same time.
                                                 In the July 25.1990 Notice. EPA
                                               solicited comments on whether the
                                               contaminant source assessments.
                                               conducted under State Wellhead '
                                               Protection Programs (see section 1428 of
                                               the SDVVA) could be used for the
                                               vulnerability assessments and  what the
                                               relationship of the two assessments
                                               should be. Commenters were supportive
                                               of this concept but requested that
                                               specific guidance be developed to
                                               determine how this might be
                                               accompliohed and where  it is
                                               appropriate.
                                                EPA intends to issue a guidance that
                                               will  give flexibility to States in
                                               conducting vulnerability assessments
                                               and  allow them and local public water
                                               systems to meet  these and similar
                                               requirements under the Wellhead
                                               Protection Program, satisfying the
                                               requirements of both programs  with one
                                               assessment Additionally, this combined
                                               assessment approach may be used to
                                               meet similar requirements under the
                                               evolving Underground Injection Control
                                               (UIC)—Shallow Injection  Well Program.
                                                g. Relation  to the Wellhead Protection
                                              fWHPf program. As stated in dve
                                              January 1991 Notice, the Agency plans
                                              to integrate particular elements of the
                                              Public Water  System. Wellhead
                                              Protection, and U1C programs related to
                                              contaminant source assessments around
                                              public water supply wells. Specifically,
                                              the Agency plans to prepare a gwdance
                                              document on groundwater contaminant
                                              source assessment that merges the
                                              vulnerability assessment of the  PWS
                                              program for SOCs and VOCs with the
                                              wellhead delineation and contaminant
                                              source which  can be used to establish
                                              priorities of UIC wells. This integration
                                              is expected to assist State and local
                                              drinking water program managers
                                              responsible for groundwater supplies to
                                              more efficiently and effectively
                                              administer the portion of their program*
                                              addressing source protection and will be
                                              the basis for determining monitoring
                                              frequency. The guidance will give States
                                              flexibility in revising vulnerability/
                                              contaminant scarce assessments.
                                                Section 1420 of the SOWA requires
                                              each  State to submit a WHP program for
                                              EPA review and approval in order to be
                                              eligible for grant funds to support the
                                              State's wellhead protection efforts. The
                                              implementation of WHP programs by
                                              States may be phased in to allow
                                              resource* to be ased most effectively.
                                              This matter can be addressed in the
                                              State WHP submittal.

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              Federal lUgtater / Vol. 57. No. 138  /  Friday. July 17. 1992 / Rales and Regulation*       31823
   When States submit WHP programs
 for approval in the future, program
 documents should address how the
 State will phase requirements for
 Wellhead Protection Areas (WHPAs)
 with other PWS regulations. In some
 States, to be most effective, this program
 integration may need to be
 accomplished-through1 a coordinating •••
 agreement or other mechanism among
 several State agencies. The guidance
 would  allow States to tailor their
 program provisions to conditions in the
 States, within broad guidelines.
 Information from the other related
 groundwater programs (such  as
 Superfund. RCRA) will be useful in this
 assessment. This information also
 includes identification of sources not
 regulated under Federal programs, but
 perhaps regulated by States,  such as
 septic tanks. Therefore. States may be
 able to meet similar requirements of
 these three programs through following
 a general set of guidance procedures.
   A State may choose from several
 methods to delineate WHPAs. As long
 as the method is determined  to be
 protective, a State may choose a
 simplified method described  in
 "Guidelines for the Delineation of
 Wellhead Protection Areas" |USEPA.
 1987a). If a State desires more
 information for use in the decision-
 making process, it may choose more
 sophisticated methods identified in the
 "Guidelines." EPA has made  available
 to States and local agencies computer
 software and training for use of the
 "Guidelines" to make the process of
 VVHPA delineation less difficult.
   WHPAs may incorporate recharge
 areas as long as they are within the
 jurisdiction of the agencies identified in
 the EPA-approved programs. However,
 WHPAs must meet the requirements of
 this rule if they are to be used to make
 monitoring waiver determinations. The
 State cannot accept a WHP program in
 lieu of a vulnerability assessment if the
' recharge area is not covered  to meet all
 the requirements of this rule.
   Once a WHPA is delineated, a State
 may desire to apply a range of
 assessment measures to define
 hydrogeologic vulnerability within the
 delineated area. A State may decide on
 a method of assigning priorities to  the
 public water systems based-on
 vulnerability, size, or other criteria
 acceptable to EPA.
   EPA's Ground-Water Protection
 Division has developed a document
"^"entitled "Managing Ground Water
• Contaminatio'n Sources in Wellhead
 Protection Areas: A Priority Setting
 Approach" [USEPA. 1991hJ to help
 States and local water supply managers
 prioritize potential contaminant sources
 in carrying out their programs for
 resource protection, a concern of one
 commenter. This system could also be
 used in setting monitoring priorities but
 was not designed specifically for that
 application. The States may use the
 regulatory mechanisms available to
 them (e.g.. RCRA permits, NPDES
. permits) to determine the point sources; '
 of regulated, and potentially
 contaminating, substances in or near
 areas needing protection, such as
 wellhead and recharge areas.
   h. Ground water'policy. The Agency
 now has a new. integrated ground-water
 policy. In July. 1982. EPA established a
 Ground-Water Task Force to review the
 Agency's ground-water protection
 policies. The outcome of this  effort is the
 Ground-Water Task Force Report,  which
 includes EPA's Ground-Water
 Protection Principles [USEPA. 1991e).
 The Principles are intended to foster
 more effective and  consistent decision-
 making in all Agency decisions affecting
 ground water.
   With respect to prevention, the  •
 Principles call for ground water to be
 protected to  ensure that the nation's
 currently used and  reasonable expected
 drinking water supplies, both public and
 private, do not present adverse health
 effects and are preserved for present
 and future generations. Ground water
 should also be protected to ensure  that
 ground water that is closely
 hydrologically connected to surface
 waters does  not interfere with the
 attainment of surface water quality
 standards, which are designed to protect
 the integrity  of associated ecosystems.
 Ground-water protection should be
 achieved through a variety of means
 including: pollution prevention programs
 aimed at eliminating and minimizing the
 amount of pollution that could
 potentially affect ground water, source
 control, siting controls, the designation
 of wellhead protection areas  and future
 water supply areas, and the protection
 of aquifer recharge areas. Efforts to
 protect ground water must consider the
 use, value, and vulnerability of the
 resource, as  well as social and economic
 values.
   With respect to remediation, the
 Principles call for activities to be
 prioritized to minimize human exposure
 to contamination risks first, and then to
 restore currently used and reasonably
 expected sources' of drinking water and
 ground water closely hydrologically
 connected to surface waters, whenever
' such restorations arc practicable and
 attainable.
   With respect to Federal. State, and
 local responsibilities, under the
 Principles, the primary responsibility for
 developing and Implementing
 comprehensive ground-water protection
 programs continues to be vested with
 the States. An effective ground-water
 protection program must link Federal.
 State, and local activities into a
 coherent and coordinated plan of action.
 EPA should continue to improve
 coordination of ground-water protection.:
 efforts within-Jhe Agency and with other
 Federal agencies with ground-water
 responsibilities.
  This rule responds to the Ground-
 Water Protection Principles in the
 following ways. With respect to the
 Principles' emphasis on prevention, this
 rule sets MCLs and monitoring
 frequencies for 18 synthetic organic and
 five inorganic chemicals. These MCLs
 will be used for ground water protection
 (i.e.. as an indication of possible need
 for source control) as well as surface   •
 water protection. The rule also
 recognizes Slate wellhead protection
 areas as a method of prevention and a
 basis for granting waivers.
  With respect to the allocation of
 Federal. State, and local responsibilities,
 this rule gives States the authority to
 grant reductions in monitoring
 frequency, based on a vulnerability
 assessment. The guidance document for
 this rule  will give flexibility to the States
 in conducting vulnerability assessments.
 As  a method of coordination among the
 PWS. UIC. and Wellhead Protection
 Programs, the guidance document will
 allow States to use the methods and
 approaches of the Wellhead Protection
 Program in meeting the requirements for
 vulnerability assessments.
  i. Initial and repeat base monitoring.
 Initial monitoring is defined as the first
 full three-year compliance period that
 occurs after the regulation is effective.
 As  described in the January 1991 Notice
 [56 FR 3564], under the standard
 monitoring framework. States have
 flexibility to schedule monitoring for
 each system during the three-year
 compliance period. As discussed earlier.
 all systems must monitor at the base
 monitoring frequency unless a waiver is
 obtained. The initial monitoring period
 for today's regulation begins.fanuary 1,
 1993 and ends December 31,1995 for
 public water systems having 150 or more
 service connections. For systems having
 less than 150 connections, the initial
 monitoring period will be from fanuary
 1.1996 through December 31.1998. After
 the system fulfills the initial (or first)
 base monitoring requirement, it must
 monitor at the repeat base frequency.
 Generally the repeat base frequency is
 the same as the initial monitoring
 frequency but in some instances the
-base monitoring frequency may be

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31B24       Federal Register / Vol. 57. No. 138 / Friday. July 17.  1992 / Rules and  Regulations
reduced baaed on previous analytical
results.              '
  Also, under today s rule, EPA is
requiring the Stales to establish a
sampling schedule that may result in
approximately one-third of the systems
monitoring during reach of the three
years of a compliance period at the
State's discretion. States will have the   •
flexibility to designate which systems
must monitor each year based upon
criteria such as system size.
vulnerability, geographic location, and
laboratory access. EPA believes that
allowing States the discretion to
schedule monitoring for each system
during the compliance monitoring period
will enable States to manage their
drinking water programs more
efficiently.
   In cases where EPA is the primacy
authority for today's regulation (i.e..
where the Slate has not adopted
regulations corresponding to the
NPDWRs in today's rule by its effective
date, and in States and on Indian lands
where EPA retains primary enforcement
responsibility), systems will be required
 lo complete monitoring within 12 months
after notification by EPA. In such cases.
EPA intends to use a prioritizing scheme
 similar to the kind that the States will
 use. This should minimize the disruption
 to the regulated community when the
 State does adopt the requirements and
 begins to develop its own monitoring
 schedules for systems within the State.
   Once a system is scheduled for the
 first, second, or third year of a
 compliance period, the repeat schedule
 is set for future compliance periods. For
 example, if a system is scheduled by the
 State lo complete the initial base
 requirement by the end of the first year.
 all subsequent repeat base monitoring
 for lhal syslem musl be completed by
 the end of the first year in the
 appropriate three-year compliance
 period. This is necessary to prevent
 systems from monitoring in the first year
 of the first compliance period and the
 third year of the repeat base period.
 4. Monitoring Frequencies
   a. Inorganics—(I) Initial and repeat
 base requirements. In the July 1990
 Notice. EPA proposed that surface water
 systems monitor annually and
 groundwater systems monitor every
  three years. Some commenters
  supported lhal frequency. Other
  commenters suggested thai the Agency
  should allow waivers.based on
  vulnerability assessments for the initial
  round of monitoring. The monitoring
  frequencies in today's rule are identical
  to these proposed frequencies. EPA
  disagrees with commenters regarding
  the issuance of waivers in lieu of an
initial round of monitoring. A reduction
in monitoring frequency may be
appropriate if the levels found are
reliably and consistently below the MCL
(see discussion on decreased monitoring
below). Systems with 150 or more
service connections will be required to
take the initial base sample for each
inorganic during the initial compliance
period of 1993 to 1995 (subject to State
scheduling). Surface water systems with
150 or more service connections that are
on an annual sampling schedule are
required to start in 1993.  '
  (2) Increased monitoring. In the
January 1991 Notice. EPA added a
requirement that systems that exceed
the MCL (either in  a single sample or
with the average of the original and
repeat sample) and which, consequently.
are out of compliance must immediately
(i.e.. the next calendar quarter after the
sample was taken) begin monitoring
quarterly. Systems must continue to
monitor quarterly until the primacy
agent determines that the system is
"reliably and consistently" below the
MCL Groundwater systems must take a
minimum of two samples and surface
water systems must take a minimum of
four samples after the last analytical
result above the MCL. before the Stale
can reduce monitoring frequencies back
to the base requirement (i.e.. annually
for surface systems and every three
years for groundwater systems).
   EPA made this change for several
reasons. First, it is consistent with the
monitoring requirements contained
elsewhere in this rule that more frequent
 monitoring occur in instances of non-
 compliance. Second. EPA believes that
 systems that are out of compliance
 should, in general, monitor more
 frequently to determine the extent of  the
 problem. If EPA has not made this
 change, groundwater systems that
 exceed the  MCL could continue to
 monitor every three years. EPA believes
 the previous frequencies for ground and
 surface systems were not adequale lo
 protect the public in those cases where
 systems exceeded the MCL.  :
   (3) Decreased monitoring. In both the
 May 1989 and the July 1990 Notices, EPA
 proposed that systems be allowed to
 reduce the  monitoring frequency to no
 less  frequent than once every 10 years
 between monitoring episodes provided a
 syslem had previously taken ihree
 samples that were all less than 50
 percent of the MCL Stales would base
  their decision on prior analytical results.
  variation in analytical results, and
  system changes such as pumping rates
  or stream flows/characteristics.
    EPA received numerous comments on
  Ihe 50 percenl trigger for reduced
  monitoring with most commentera
opposing Ihe 50 percenl Irigger. calling it
arbitrary. In the January 1991 notice.
EPA decided to eliminate the 50 percent
trigger and change the condition for
reduced monitoring to require three
compliance samples, all of which are
"reliably and consistently" less than the
MCL  to give the.States-additional.;.  • '••
flexibility to decide which systems  are
eligible for reduced monitoring. Systems
meeting this criterion are also eligible
for reduced monitoring for the
contaminants in today's rule. While
States have discretion in making this
delerminalion. EPA believes that as a
minimum, all individual samples should
be below the MCL before the
determination should be made.
  Most commenters supported the 10-.
year time frame as a reasonable
monitoring frequency for reduced
monitoring. Because EPA has adopted a
3/6/9-year compliance cycle. EPA has
changed the maximum reduced
monitoring frequency from the proposed
10 years to 9 years to gain consistency
in its  regulations. EPA believes this
change will have a minimal impact on
systems..EPA is requiring at least one of
the three previous samples to be taken
since January 1.1990. The other two
samples could be taken at any time after
January 1,1988. Because the reduction in
monitoring to every nine years begins in
the 1993-2001 compliance cycle. EPA
believes that one sample must be recent
(i.e., taken after January 1.1990 for
systems scheduled to monitor in 1993) to
preclude ^unduly long time frames
occurring between samples. Data
obtained to satisfy monitoring
requirements for unregulated
contaminants specified in the January
1991 notice may be used to reduce  the
monitoring frequencies. Systems
receiving a waiver may monitor at any
 time during the nine-year compliance
 cycle, as designated by the State.
   b. Cyanide. In the July 1990 Notice.
 EPA proposed monitoring requirements
 for Ihe IOCS applicable lo all community
 (CWS) and non-transienl non-
 communily waler syslerris. Several
 commenters disagreed with Ihe
 requiremenl lo monitor for cyanide at
 non-vulnerable systems. They argued
 that the main sources of cyanide
 contamination are industrial and
 manufacturing processes, not natural
 occurrence, and thai il would be more
 appropriate lo regulale cyanide under
 the requirements that apply to synthelic
 organic compounds (SOCs), which
 dislinguish vulnerable and non-
 vulnerable systems.
   The Agency agrees with these
 commenters and has changed the
 requiremenl for cyanide lo require only

-------
              Federal Register  /  Vol. 57.  No. 138  /  Friday.  July  17. 1992 / Rules and Kegu/atfona    "  31825
 vulnerable systems to monitor, provided
 a waiver (by vulnerability assessment)
 is available and has been granted by the
 State.
   Other commenters stated that the
 monitoring requirements for all the lOCs
 in today's notice should apply to
 vulnerable systems only, and that EPA,
 should allow waivers based on
 vulnerability assessments for the initial
 round of monitoring. EPA disagrees with
 these commenters (except for cyanide
 because it does not occur naturally at
 concentrations near the MCL) because
 some minimum monitoring requirements
 for the inorganic contaminants will
 provide a baseline of data on the natural
 background levels expected for these
 contaminants. Systems may qualify.for
 reduced monitoring once a baseline of
 data shows levels that are reliably  and
 consistently below the MCL thus
 decreasing the monitoring burden.   .
   c. Volatile Organic Contaminants
 (VOCs)—(I] Initial and repeat base
 requirements. In the rule promulgated in
 July 1987 setting MCLs for eight VOCs,
. EPA required all systems to take four
 consecutive quarterly samples.
 Groundwater systems that conducted a
 vulnerability assessment and were
 judged not vulnerable, however, could
 stop monitoring after the first sample
 provided no VOCs were detected in that
 initial sample.'Repeat frequencies for all
 systems vary by system size, detection,
 and vulnerability status.
   On July 1.1991. EPA amended the
 monitoring  requirements for VOCs  to
 streamline the requirements and to
 make all VOC requirements consistent
 [56 FR 30267]. For the contaminants in
 today's rule, the July 1990 proposal
 made distinctions in base  requirements
 for VOCs between ground and surface
 water systems, less than and more  than
 500 service connections, and vulnerable
 and non-vulnerable systems. In today's
 final rule, to be consistent with the July
 1991 rule, and for the reasons discussed
 there [56 FR 30267], EPA is requiring all
 groundwater systems as well as surface
 water systems to initially take four
 quarterly samples for the VOCi
 (dichloromethane, 1,2,4-
 trichlorobenzene, and 1.1,2-
 trichloroethane). regardless of size or
 vulnerability status. Systems that do hot
 detect VOCs in the initial round of four
 quarterly samples are required to
 monitor annually beginning in the next
• calendar year after quarterly sampling is
 completed. For example, systems which
 complete quarterly monitoring in
 calendar year 1993 are required to  begin
 annual monitoring in 1994. The State
 may allow groundwater systems, which
 conducted three years of sampling and
have not detected VOCs to take a single
sample every three years thereafter. The
reasons for these changes are further
explained in the January 1991 notice [56
FR 3566].
  In the May 1989 proposal covering 38
contaminants. EPA requested comment
on whether vulnerable-systems may
take only one sample if no VOCs are
detected in the initial year of
monitoring. EPA's intent was to require
quarterly sampling in vulnerable
systems, but most commenters opposed
a change to more frequent monitoring.
Based on the comments received on that
notice. EPA specified in the January
1991 final rule for 33 of the 38
contaminants that vulnerable systems
will be required to take one annual
sample (instead of four quarterly
samples) if no VOCs were detected in
the initial (or subsequent) monitoring.
For consistency, EPA has adopted this
same requirement for the VOCs in
today's rule.
  (2) Increased monitoring. In the
proposal, systems detecting VOCs
(defined as any analytical result greater
than 0.0005 mg/1)  were required to
monitor quarterly. In today's rule. EPA
is requiring systems that detect VOCs to
monitor quarterly  until the State
determines that the iiystem is "reliably
and consistently"  below the MCL.
However, groundwater systems must
take a minimum of two samples and
surface water systems must take a
minimum of four samples before the
State may reduce the monitoring to the
base requirement (i.e., annual sampling).
  Systems remain on an annual
sampling frequency even if VOCs are
detected in subsequent samples, unless
an MCL is exceeded (or if the State
otherwise specifies). In this case, the
system returns to quarterly sampling fri
the next calendar quarter until the State
determines that the new contamination
has decreased below the MCL and is
expected to remain reliably and
consistently below the MCL This
determination shall again require a
minimum of four quarterly samples for
surface water systems and two
quarterly samples for groundwater
systems.
   EPA has made thin change because
some systems may detect VOCs at a
level slightly above the detection limit
EPA believes that where the State can
determine that contamination is
"reliably and consistently" less than the
MCL those systems should be able to
return to the base monitoring
requirement (i.e^ annuallyL. Giving
States the discretion to determine
whether systems meet this criterion may
allow States to give monitoring relief to
some systems.
  (3) Decreased monitoring. States may
grant waivers to systems that are not
vulnerable and did not detect VOCs
while conducting base monitoring.
Vulnerability must be determined using
the criteria specified above in-the
•discussion of vulnerability assessments.
EPA anticipates that most systems  will
not be able to qualify for a "use" waiver
because of the ubiquity of VOCs.
However, systems conducting an
assessment that considers prior
occurrence and vulnerability
assessments (including those of
surrounding systems), environmental
persistence and transport, source
protection. Wellhead Protection
Assessments, and proximity to sources
of contamination may apply to the  State
for a "susceptibility" waiver. If the
waiver is granted, systems are required
to take one sample and update the
current vulnerability assessment during
two consecutive compliance periods
(i.e., six years). The vulnerability
assessment update must be completed
by the beginning of the second
compliance period. EPA has increased
the time frame from five to six years to
bring the five-year monitoring frequency
in the proposal in  line with the 3/6/9-
year frequencies specified in the
•standard monitoring framework.
  States have the  discretion to set
subsequent frequencies in systems  that
did not detect VOCs in the initial round
of-four quarterly samples and that are
designated as not  vulnerable based on
assessment. The repeat monitoring
frequency for groundwater systems
meeting this criteria shall be not less
than one sample every six years as
discussed above. For surface water
systems meeting this criteria, the repeat
frequency is at State discretion.
  d. Synthetic Organic Chemicals
(SOCs)—(1) Initial and repeat base
requirements. In the proposal, systems
were not required to monitor for the
non-volatile SOCs unless the State, on
the basis of a vulnerability assessment,
determined the system to be vulnerable.
Once determined vulnerable by the
State, a system would be required to
take four consecutive quarterly samples,
EPA requested comment on an
alternative approach that would require
all systems to monitor for all
contaminants. As  discussed below,
today's requirements specify that all
systems monitor for all SOCs by taking
four quarterly samples every three
years, unless decreased or increased
monitoring requirements apply. All
systems-are eligible for waivers from the
quarterly monitoring requirement as

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  31826        Federal Register /  Vol. 57.  No. 138  / Friday. July 17.  1992 / Rules and  Regulations
  discussed in the section on decreased
  monitoring below.
    Most comments on the proposal
  revolved around two issues—the
  requirement that systems monitor
  quarterly and the requirement that all
  systems monitor at the time of highest
  vulnerability. Many commenters staled
  thai quarterly monitoring was not
  necessary to detect changes in
  contamination Many ccmmenters
  recommended annual monitoring for
  pesticides. After reviewing the
  information and comments submitted.
  EPA believes that quarterly monitoring
  remains the best scheme lo determine
  contamination. Occurrence information
  available to EPA indicates that seasonal
  fluctuations from runoff and
  applications of pesticides may occur:
  thus, quarterly monitoring is better than
  annual monitoring to determine
  pesticide contamination. In some cases.
  Slates may consider it appropriate to
  require monitoring at greater
  frequencies than those specified by
  today's rule to better determine
  exposure. States have the option to
  require monitoring at greater
  frequencies than the federal minimums
  in today's rule. Systems, of course, may
  always monitor more frequently when
  they deem it prudent.
   Most comorienters opposed the
  requirement to monitor at the time of
 highest vulnerability, stating the highest
 vulnerability, stating that highest
 vulnerability cannot be predicted  or
 determined. Several commenters stated
 that the requirement to monitor at the
 time  of highest vulnerability was
 unenforceable. EPA agrees and
 eliminates this requirement from today's
 rule.  However. States are advised to
 examine sampling practices of systems
 to assure that periods of likely
 contamination are not avoided. This is
 especially true for surface water
 systems monitoring for pesticides after
 rainfall and/or application of pesticides.
   EPA proposed that systems conduct
 repeat monitoring every three or five
 years, depending on system size and
 ground/surface distinctions.- In today's
 rule, the repeat monitoring frequency for
 all systems is set at four consecutive
 quarterly samples each three-year
 compliance period, unless decreased or
 Increased monitoring requirements
 apply. EPA has made several
 adjustments For systems that do not
 delect contamination in the initial
 compliance period. After the initial
 monitoring round is completed, systems
 that serve 3.300 or more persons may
 reduce the sampling frequency to two
 samples In one year during each
compliance period. Systems serving less
   than 3.300 persons may reduce the
   sampling frequency to one sample per
   compliance period. EPA has increased
   the frequency at which small systems
   must monitor in this rule from every five
   years to every three years, because EPA
   believes that this change will offer
   greater health -protection/ EPA- believes
   that every five years is too long an
   interval to determine changes in
   consumer exposure.
    EPA has made the granting of "use"
   waivers for pesticides easier in this rule
   by permitting States to grant "area
   wide" or "Statewide" waivers based
   upon pesticide use information. EPA
  anticipates that many systems will be
  able to obtain a "use" waiver.
  Therefore, the impact of the increased
  monitoring frequency discussed in the
  above paragraph should be minimal. For
  those systems not able to obtain a
  waiver (i.e.. vulnerable systems), EPA
  believes it is appropriate to monitor at
  three-year intervals to determine
  contamination.
    (2) Increased monitoring. EPA
  proposed that systems with 500 or less
  service connections that detect SOCs
  contamination monitor annually, while
  systems with more than 500 service
  connections that detect SOCs would
  monitor quarterly. EPA defined
  detection as greater than 50 percent of
  the MCL Many comments revolved
  around  the 50 percent trigger. Consistent
  with the above discussion concerning
  VOCs. EPA is redefining detection for
  SOCs to mean the method detection
  limit (as specified in the approved
 analytical method). EPA believes it is
 appropriate to use the method detection
 limit as  the trigger for increased
 monitoring because detection implies
 that the  potential for increasing
 contamination exists. Consequently,
 additional monitoring is required to
 determine the extent and variability of
 SOCs contamination. Jn today's rule, all
 systems that detect SOCs must comply
 with the baseline monitoring
 requirements (i.e.. waivers are-not
 available).
   As described in the proposal, upon
 detection, all systems must immediately
 begin quarterly monitoring. The State
 may reduce the requirements to annual
 monitoring for SOCs after determining
 that samples are "reliably and
 consistently" below the MCL. A
 reduction to annual monitoring may
 occur after a minimum of two samples
 for groundwater and four samples for
 surface water systems. After three years
 of annual monitoring which remains
 "reliably and consistently" below the
MCL. systems can return to the base
monitoring requirement for SOCs (i.e..
   four quarterly samples every three
   years).
     (3) Decreased monitoring. Systems
   that obtain a waiver from the monitoring
   requirements are not required to
   monitor. All systems are eligible for
   waivers in the first Hires-year
  'compliance period of 1993 to 1995. AS
   discussed above. EPA has simplified the
   vulnerability assessment procedures bv
   allowing the system to assess whether"
   the contaminant has been used.
   transported, mixed, or stored in the
   watershed or zone of influence. Where
•  previous SOCs use in the area can be
  ruled out, systems may apply to the
  State for a use waiver. EPA's intent in
  promulgating this change is to make it
  easier for systems to obtain waivers in
  those situations where the chemical has
  not been used. States may be able to
  determine that the entire State or
  specific geographic areas of the Stale
  have not used the contaminant and
  consequently grant "area wide"
  waivers. Systems that cannot determine
  use may still qualify for a waiver by
  evaluating susceptibility according to
  the criteria discussed in the VOC
  section  above. Waivers must be
  renewed every three years.
   e. Sulfates. Some commenters
  believed that systems violating the
  sulfate MCL should not be required to
  monitor quarterly, because sulfate  levels
  are stable, and additional monitoring
  would provide no new information. EPA
  has collected additional data  on sulfate
  levels and agrees with the comment.
  However, as discussed above. EPA is
  not setting a final MCL for sulfate today
 and is. therefore, not setting final
 monitoring requirements for sulfate. For
 the time being, monitoring for sulfate
 will continue to be required under the
 provisions for monitoring of unregulated
 contaminants established in the January
 1991 rulemaking.

 5. Other Issues
   a. Compliance determinations. One
 commenter opposed the use of a single
 sample to determine compliance with
 the IOC MCLs for systems that monitor
 yearly or less frequently. The
 commenter argued that this procedure
 provides an advantage to the system
 required to monitor quarterly, because if
 an annual average.is the basis for
 compliance an entire year may go by
 before the system monitoring quarterly
 is deemed out of compliance and public
 notification is required, whereas the
system moriitbring annually is deemed
out of compliance immediately if it
violates the MCL once. The cemmenter
recommended that all systems monitor

-------
                               f VAL' 57. 'fk>.' 13B / 'Pti^ay,  July  17. 1992"/ RuJes  and tfeguJatiohs       3385
on a quarterly basis with compliance
based on a running average.
  EPA believes that quarterly
•monitoring is not generally necessary for
the lOCs and is no longer requiring
initial quarterly monitoring. However, if
the system exceeds  the MCL at any
sampling point, then the system is out of
compliance (based.on the original and.- •
one confirmation sample, at State
discretion) and quarterly monitoring is
thereafter required.  For.those systems
monitoring more frequently than
annually, the Agency requires that if any
one sample would cause the  annual
average to be exceeded, then the system
is out of compliance immediately and
public notification is required. In
addition, a system, if it wishes, may
apply to the State to conduct more
frequent monitoring of the lOCs than the
minimum frequencies specified in this
regulation (see § 141.23(h)). Under
§ 141.23(i), systems  that are monitoring
at a greater than annual frequency
determine their compliance by a running
annual average of results.
  EPA believes that this approach puts
emphasis on  monitoring on those
systems that  are of greatest concern
while providing cost savings to most
systems.
  b. Confirmation samples. Several
commenters stated that collection of a
confirmation sample within 14 days of
the original sample  is unrealistic. EPA
continues to believe that the 14-day
period is reasonable for the collection of
a confirmation sample since  it is
important to  get a conclusive  '
determination of any MCL exceedance
as  soon as possible. In addition, one
commenter stated that confirmation of
negative samples should not be required
due to cost constraints.  In response, the
collection of confirmation samples is not
 a federal requirement, but a  State •
 option. The Agency agrees that States
 should consider costs in making
 decisions about confirmation samples,
 especially for negative results.
   c. Compositing. EPA proposed to
 allow systems, at the discretion of the
 State, to composite up to five samples.
 Compositing must be done in the
 laboratory. Some commenters supported
 compositing as a methodology to cut
 costs. In this final rule, EPA  is limiting
 compositing among different systems to
 only those systems serving fewer than
 3.300 people. Systems serving greater
 than 3,300 persons will be allowed to
 composite but only within their own •
 system. EPA also requested comments
 on whether State discretion  on
 compositing is necessary or whether
 systems can composite automatically
 without State approval. Several Statei-
 opposed this change; consequently, the •
final rule is unchanged from the
proposal. EPA believes that compositing
is to be used only when cost savings are
important and systems alone should not
make that determination. Today's rule
limits compositing to those
contaminants where theMDL is less
than one-fifth of the MCL, in order to
avoid situations where compositing of.
five samples would mask the presence
of a contaminant in one sample by
dilution with the other samples.
  d. Polynuclear Aromatic
Hydrocarbons (PAHs). In the July 1990
proposal. EPA requested comments  on
the following monitoring issues related
to the PAHs: (1) Should fluoranthene
and naphthalene be used as indicators
of the potential  presence of carcinogenic
PAHs: (2) should EPA require sampling •.
at the tap: and (3) should PAH
monitoring be at State discretion if the
State bans the use of coal tar in
distribution systems. Below is a
summary of the comments on these
issues and EPA's response.
  Use of indicators: Commenters
generally opposed the use of non-
regulated PAHs such as naphthalene
and fluoranthene to determine a
system's vulnerability to PAH
contamination and recommended that
systems monitor only for BaP (and any
other PAHs the Agency decides to
regulate). For the reasons stated  earlier
in today's notice. EPA is promulgating
an MCLG and an MCL for BaP only at
this time. On reconsideration, EPA
agrees that naphthalene and
fluoranthene are not necessarily good
indicators for the presence of BaP in
water. On reconsideration of the data,
EPA acknowledges that BaP is much
less soluble than naphthalene and
fluoranthene, and has not been found to
co-occur with them. Therefore, EPA has
decided against the use of these PAHs
as indicators of BaP contamination in
drinking water. This is consistent with
the commenters' recommendations.
  Samp/ing at the tap: EPA received
numerous comments on this issue. Most
commenters opposed sampling at the
tap, claiming that it is neither acceptable
nor appropriate to sample at the tap for
PAHs. These commenters argued that
coal tar. which  may be a major source of
PAH contamination in the distribution
system, is-not used in home plumbing
and that the tap.is a location beyond the
control of the water utility. Some
commenters suggested, however, that
sampling in the distribution system.
downstream of the lined section of the
system, may be appropriate. One
commenter further stated that
monitoring for PAHs originating from
the distribution syatem should be a
"one-time effort" under worst case
conditions.
  Elsewhere in today's rulemaking, EPf
has explained that it is regulating only
BaP Within the group of PAHs. MCLs
have not been set for other PAHs that
the proposal indicated EPA was
considering regulating.
  Further, there are data indicating that
BaP does not leach from materials in the
water delivery system (i.e.. distribution
system pipe materials, storage tanks), at
noted by one commenter. Survey of data
on leaching of BaP from U.S. water
storage/distribution systems has
revealed that data are available for at
least 36 U.S. cities. In these studies
water samples were collected from the-
treatment site as well as from one or
more locations in the storage and/or
distribution system. The  increase in
concentration of BaP from distribution
systems in these studies has ranged
from none to 2i9 ppt [Saxena et at.. 1978;
Robeck. 1978: Zoldak. 1978:
McClanahan. 1978: Alben. 1980: Basu et
al.. 1987). Laboratory studies involving
exposure of tap water to panels coated
with coal tar coating support these
findings [Alben, 1980: Lampo. 1980|.
Higher BaP concentration (78-110 ppt) in
the water was reported only in one
laboratory study where rigorous
leaching conditions not representing
actual distribution/storage system
exposure were used (Sorrell et al.. 1980|.
in addition, coal tar and  asphaltic
linings are not generally  used in home
plumbing which is usually copper.
galvanized, or plastic piping.
  Based on these studies. EPA has
concluded that contribution of BaP from
coal tar-lined storage and distribution
systems is very small overall and is only
a small percentage of the final BaP MCL.
Therefore, EPA has decided that there is
no need to set controls for BaP
contributions from the materials in the
water delivery system. This
contaminant is appropriately controlled
by controlling its levels in source water.
as is true for the other contaminants in
today's rule. Consequently. EPA has
determined that there is no need for
today's rule  to require monitoring at the
tap or anywhere else in the distribution
system.
  Coal tar ban/States' discretion for
monitoring. Commenters generally
opposed banning the  use of coal tar and
asphaltic linings in the distribution •
system and storage tanks at this time.
One commenter suggested that
additional evaluation of the potential
risks due to the use of coal tar linings in
water distribution systems is necessary
before recommending discontinuation of
their use. Another commenter stated

-------
31828
Fxfcral  R*g»tor / Vol. 57. Na 138 / Friday, faiyl7, f992 ^ Riles and • Regulations
that the banning of. the use of coal tar
may not be warranted, especially in
light of the ubiquitousness of PAHs in
foodstuffs and consumer products. One
commenter indicated that its water
supplier had halted the further use of
coal tar materials in the late 1970s. This
commenter indicated it has found cost-
effective.alternatives for both pipes and.-
tanks.
  As noted above, the Agency finds that
the contribution of BaP from coal tar
lined pipes and storage tanks is
generally very small relative to dietary
sources, as one commenter stated. It  is
possible, however, that there may be
leaching of PAHs other than BaP due to
coal tar in the distribution system. Thus,
the Agency believes that States should
carefully evaluate any actions related to
this potential source of contamination
(such as banning the further use  of coal
tar) to be sure that action is warranted.
  With respect to State discretion
Concerning monitoring requirements if it
bans the use of coal tar, one commenter
stated that vulnerable systems should
still be required to monitor, while
n.iother commenter indicated that
monitoring should be at State discretion.
and a third commenter recommended
that monitoring at the Up be at State
discretion. EPA has carefully considered
these comments and is not requiring that
systems monitor for BaP in the
distribution system, as discussed above.
D. Variances and Exemptions
1. Variances
  Under section 1415{a)(l)(A) of the
SDWA. EPA or a State that has primacy
may grant variances from MCLs  to those
public water systems that cannot
comply with the MCLs because of
characteristics of their water sources. At
the time a variance Is granted, the State
must prescribe a compliance schedule
and may require the system to
implement additional control measures.
The SDWA requires dial variances may
only be granted to those systems that
have installed BAT (as identified by
EPA). However, in limited situations ft
system may receive a variance if it
demonstrates that the BAT would only
achieve a de minimi's reduction to
contamination (see 5 142.62(d)). Before
EPA or a State issues a variance, it must
find that the variance will not result in
an unreasonable risk to health.
  Under section 1413(a)(4) of the Act.
States with primacy that choose to issut
variances must do so under conditions
and In a manner that is no less stringent
than EPA allows under section 1415.
defore a State may issue n variance, it
must find that there were no
opportumUe* for the system to (1) Join
                         another water system, or (2) develop
                         another source of water and thus
                         comply fully with all applicable drinking
                         water regulations.
                           The Act permits EPA to vary the BAT
                         established under section 1415 from that
                         established under section 1412 based on
                         a number of findings such as system
                         size, physical conditions related to -. • '••••
                         engineering feasibility, and the cost of
                         compliance. Paragraph 142.62 of this rule
                         lists the BAT that EPA has specified
                         under section 1415 of the Act for the
                         purposes of issuing variances. This list
                         mirrors the proposed list except that
                         oxidation (chlorination or ozonation) is
                         considered BAT for glyphosate, as
                         discussed in "Selection of Best
                         Available Technology" above. Tables 20
                         and 21 provide a list of the section 1415
                         BATs for the inorganic and organic
                         compounds in this rule.

                            TABLE 20.—SECTION 1415 BAT FOR
                                 INORGANIC COMPOUNDS
                                    Cnemtcal
                                                        BATs
Antimony- 	 _ 	 _ .
Becylkum _...._... 	 ...__ .. ._._
CysnxJe 	 _.._ 	 .___ .... ___.
Niekal 	 —„-—,„.,..,....
ThaJhum 	 _ 	 _ 	 _

27
2567
5 7 10
• 56,7
57

                           Kff 10 BATs in TabJe 2:
                           '-Coaoulabon/FiRration  (not  BAT lor systems
                         with <500 service connections).
                            -ton Exchange.
                            -Urn* Softenng. (not  BAT  lor »>mms  w«l
                         <500 service connections).
                            • Reverse Oimosft.
                           o.Chtormo.
                            '-Ultraviolet.

                            TABLE 21'.—SECTION 1415 BAT FOR
                                 ORGANIC COMPOUNDS
Chemical
Benzo(a)pjren« . — 	
D*tapon_.
Dtcnforomttharw 	 ... 	 ,
Di(2-etn>«wxy<)adipaM -
di(2-
etnyttwxyQphthatate.
Dinosab 	 	
Oquat 	 ......
EndotnaJJ .
Endrin ._ 	 '. 	 !.."...
GtypnosaM 	
HcmcMorocyc^o*
pentaoerw.
Oxamyl (Vyd*t») 	
pjctorwn _„._.„ 	 -......,
S*m*zsr* 	 	
1 . 1 i-TricWoro«th«n«_.
2.3.7.6-TCOO (Dioxin)_.
PTA«
- 	 —-
X
X
	
X
X
GAC«
X
X

X
X
X
X
X
X
X
X
X
X
X
X
ox»



X


                          1 PTA-Pucfceo lower >ei«Boo.
                          * GAC-OranUar aOtalad ctrtx
                          * OX-Owtoton {ChtonnMon or Owna&an*.

                         2. Exemptions

                           Under section 1418(a), a State or EPA
                         may grant an exemption extending
 deadlines for compliance with a
 treatment technique or MCL if it finds
 that (1) due to compelling factors (which
 may include economic factors), the PWS
 is unable to comply with the
 requirement: (2) the exemption will not
 result in an unreasonable risk to human
 health: and (3) the system was in
 operation on trie-effective date'of the'. •'•'•
 NPDWR, or.  for a system not in
 operation on that date, no reasonable
 alternative source of drinking water is
 available to the new system.
   In determining whether to grant an
 exemption. EPA expects the State to
 determine whether the facility could be
 consolidated with another system or
 whether an alternative source could be
 developed. It is possible that very small
 systems  may not be able to  consolidate
 or find a low-cost treatment. EPA
 anticipates that States may  wish to
 consider granting an exemption when
 the requisite  treatment is not affordable.
   Under section 1416{b)(2)(B) of the Act,
 an exemption may be extended or
 renewed (in the cases of systems that
 serve 500 or less service connections
 and that need financial assistance for
 the necessary improvements) for one  or
 more  two-year periods provided that no
 unreasonable risk to the health of
 persons would result from granting the
 exemption.

 3. Point-of-Use Devices, Bottled Waters
 and Point-of-Entry Devices

  Under sections 1415(a) and 1416(b)  of
 the SDWA. when  the State grants a
 variance or exemption, it must prescribe
 an implementation schedule and any
 additional control measures that tha
 system must take. States may require
 the use of point-of-use  (POU) devices,
 bottled water, point-of-entry (POE)
 devices and other mitigating devices as
 "additional" control measures'if an
 "unreasonable risk to health" would
 otherwise exist Sections 1424>7 and
 142.62 allow these measures as an
 interim control measure while a
 variance  or exemption  is in effect

4. Public^ Comments
  EPA received several comments
regarding the  issuance  of variance* and
exemptions. Comments were concerned
about the high cost of the proposed BAT
technologies (reverse osmosis and Ion
exchange) for sulfate for small systems
that may  need to obtain variances under
section 1415 of th« SDWA. One
commenter states that variances and
exemption!) are temporary and that
systems will still be required to comply
at some point This commenter further
states that any cost saving due to
granting of temporary variances or

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                Federal Register / Vol. 57. No. 138 / Friday. July 17. 1992 / Rules and Regulations
                                                                      311
exemptions must be reduced by the
costs of complying with the "interim
control measures" required under the
Act and the transaction costs of
documenting and applying for exempt
status.
  Another commenter argued that
health protection is not ensured because
systems may be granted variances and -
exemptions due to the prohibitive cost
to implement available technology to
achieve lower sulfate levels. This
commenter recommended the use of a
monitoring program and public
notification for sulfates instead of an
MCL.
  Two commenters stated that EPA
should allow States the discretion to
grant variances from the sulfate MCL for
all systems (large as well as small), as
long as the variance does not result in
an unreasonable risk to health. These
commenters recommend that concerns
about the water supply and availability
should be considered to be pertinent
"characteristics of raw water sources"
and that provision of public information
and alternate water supplies for
sensitive populations could be regarded
to be appropriate BATs for granting
variances.
  EPA Response: In response to the
commenters concerned about the high
costs of reverse osmosis and ion
exchange for sulfate removal, the
Agency agrees that these costs are high
for very small systems. A majority of the
systems which would have been
affected had EPA not deferred the
sulfate rule serve 500 or less persons.
Exemptions for these systems could
have been renewed as long as the
system qualifies for an exemption under
section 1416(b) of the SDWA. The costs
given in the Regulatory Impact Analysis
(RIA) for regulating sulfate assumed no
variances and exemptions are granted
(i.e., that all systems treat). Thus, the
Agency believes that costs to meet a
sulfate regulation would have been
lower than those projected in the RIA,
after consideration of costs associated
with granting variances and exemptions.
  In response to the commenter that
alleged lack of health protection
because variances and exemptions will
be granted, a variance or exemption can
only be granted if it will not result in an
unreasonable risk to health. In addition,
the associated public notification
requirements whenever an MCL
exceedance occurs would have provided
additional protection to consumers.
  In response to the commentere that
recommended allowing the States
discretion to grant variances to all
systems regardless of size. States do
have the discretion to grant variances to
all public water systems that cannot
 comply with the MCLs because of
 characteristics of their source waters.
 Variances generally can only be granted
 if the systems have installed BAT and
 have failed to meet the MCL. In granting
 variances, the State may prescribe
 interim control measures such as public
 information or provision of alternate -.  . v
 water supplies (e.g.. bottled water). •
   The population served by transient
 water systems is likely to be at greatest
 risk of suffering from the adverse effects
 of sulfate. Because populations that
 regularly consume! water containing
 sulfate will acclimate to its effects, it is
 people using higher sulfate water on a
 transient basis that make up the.
 population at risk. This group is largely
 travelers, i.e., visitors to communities or
 facilities that are non-transient non-
 community public  water systems, or  •
 visitors to facilities such as gas stations.
 campgrounds or other recreational
 facilities that serve an almost
 exclusively transient population. It is
 this latter group of facilities or public
 water systems that are most likely to
 serve water to non-acclimated persons
 who are at risk from high sulfate.
   Sulfate's high treatment cost, low risk.
 and impact primarily on the transient
 consumer, combine to create a different
 set of regulatory challenges than posed
 by most other drinking water
 contaminants. For these reasons, EPA is
 deferring the sulfate standard for a
 current undetermined period.
 Specifically, EPA is seeking to extend
 the legal deadline  for establishing the
 sulfate standard for a period that would
 allow the Agency to resolve the
 following issues: (1) Whether further
 research is needed on how long it takes
 infants to acclimate to high sulfate-
 containing water, (2) whether new.
. regulatory approaches need to be
 established for regulating a contaminant
 whose health effect is confined largely
 to transient populations, and (3) whether
 the Agency should revise its definition
 of Best Available Technology for small
 systems (i.e., what should be considered
 affordable for transient noncommunity
 water systems). During this deferral
 period, the Agency also intends to
 consider ways to expedite the process
 for granting potential exemptions and
 variances to ease the impact of these
. regulations on small systems. Also in
 the interim, EPA plans to issue a Health
 Advisory for sulfate and to encourage
 States where sulfate levels may be high
 to conduct additional monitoring and
 encourage the use of alternative water
 supplies where appropriate.
E. Public Notice Requirements

1. General Comments

  Two comments were received on the
general issue of public notification
requirements. One commenter stated
that the required public notifications
should, provide a more accurate and v
balanced explanation of potential healt
effects. The second commenter stated
that public notification should not be
required unless contaminant levels
remain excessive after BAT has been
installed.  '
  EPA Response: EPA believes that the
public notification language prescribed
is, and should be, simple and non-
technical in nature while providing
sufficient information to the public
about the health implications. EPA
believes that the statements are
accurate and balanced. The Agency  alsc
believes that the public has the right to
know whenever there is a violation of a
standard. The public water system may
supplement the notice  with additional
information such as  the steps being
taken to meet the standards as long as
the  notice informs the public of the
health risks which EPA has associated
with violation of the standards and the
mandatory health effects language
remains intact.
2. Contaminant-Specific Comments

  Two commenters provided  specific
suggestions on changes for the public
notification language for several
contaminants. These changes were
editorial in nature.
  EPA Response: EPA has made most of
the  changes suggested, as appropriate.

F. Secondary MCL for
Hexachlorocyclopen tadiene
  EPA proposed a secondary maximum
contaminant level (SMCL) based upon
odor detection levels for
hexachlorocyclopentadiene (HEX). Odor
detection for this organic chemical has
been reported at levels lower than the
MCL of 0.05 mg/1. The  July 1990 notice
proposed to   set the SMCL for this
compound at 0.008 mg/1.
  EPA received two comments on the
proposed SMCL for HEX.  One
commenter stated that an SMCL for
HEX will "erode the public's confidence
in the overall quality of the drinking
water," and recommended against an
SMCL for this compound. Another
commenter opposed the proposed SMCL
alleging it is based on an inadequate
experimental basis. The commenter
argued that the literature citation
[Amoore and Hautala. 19S3J was^based
on theoretical extrapolation (from air
odor thresholds), and the  levels have not

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31830       Federal RegUtar / Vol. 57. No. 138 / Friday. July 17.  1992 / Rules  and Regulations
been confirmed by any published
literature.
  After reviewing the public comments.
EPA has decided to defer promulgating
an SMCL for HEX. EPA disagrees with
the first comment and  believes that taste
and odor problems do  have an adverse
impact on consumers'  confidence in the
drinking-water supply. However; the v •
Agency agrees with the second
commenter that additional work is
necessary to determine appropriate
levels for aesthetic effects. Accordingly,
the Agency may initiate in the future a
"National Task Force of Experts" to
review and assess the  data, information
end opinions available with respect to
taste and odor problems in public water
supplies [as noted at 56 FR 3572, January
30.1991].
C. State Implementation
  The Safe Drinking Water Act provides
that States may assume primary
implementation and enforcement
responsibilities. Fifty-five out of 57
jurisdictions have applied for and
received primary enforcement
responsibility (primacy) under the Act.
To implement the federal regulations for
drinking water contaminants. States
must adopt their own regulations which
are at least as stringent as the federal
regulations. States must also comply on
the requirements in 40 CFR 142.12 on
revising approved primacy programs.
This section of today's rule describes
the regulations and other procedures
and policies States must adopt or have
in place to implement the new
regulations.
  To implement today's rule, States will
be required to adopt the following
regulatory requirements when they are
promulgated: § 141.23,  Inorganic
Chemical Sampling and Analytical
Requirements; § 141.24, Organic
Chemicals Other Than Total
Trihalomathanes, Sampling and
Analytical Requirements: I 141.32,
Public Notice Requirements (Le.,
mandatory health effects language to be
included in public notification or
violations): § 141.61 (a) and (c).
Maximum Contaminant Levels for
Inorganic and Organic Chemicals.
  In addition to adopting drinking water
regulations no less stringent than the
federal regulations listed above, EPA is
requiring that States adopt certain
requirements related to this regulation in
order to have their program revision
application approved by EPA. In various
respects, the NPDWRs provide
flexibility to the State  with regard to
implementation of the  monitoring
requirements under this rule. Because
Slate determinations regarding
vulnerability and monitoring frequency
will have a substantial impact with
implementation of this regulation.
today's rule requires States to submit, as
part of their State program submissions,
their policies and procedures in these
areas. This requirement will serve to
inform the regulated community of State
requirements and also help EPA in its
oversight'of State'programs. These'1'
requirements are discussed below under
the section on special primacy
requirements.

1. Special Stale Primacy Requirements
  To ensure that the State program
includes all the elements necessary for
an effective and enforceable program,
the State's request for approval must
contain a plan  to ensure that each
system monitor for the contaminants
listed in this rule by the end of each
compliance period.
  In general, commenters supported the
proposed primacy requirements. Most of
the comments .were very similar to those
made on a previous proposed
rulemaking (May 22,1989. [54 FR
22135]). including the following: The
States do not have enough resources.
States should not have to report
vulnerability assessments to EPA, and
records should be kept for less than the
40-year requirement. These issues wera
all addressed in the January 1991 rule
[56 FR 3574].
  Numerous comments were made
regarding requirements for sulfates. One
commenter was concerned about the
cost impacts on small systems trying to
achieve compliance with the proposed
MCL options of 400 mg/1 and 500 mg/1.
Under the SOW A, exemptions may be
granted by a State which would have
helped alleviate the cost impact of
compliance for sulfate. Another
commenter claimed that if variance*
and exemptions were allowed for
sulfate*, a significant portion of the
population would not be protected.
Under sections 1415 and 1416. before a
State may grant a variance or exemption
it must determine that the variance or
exemption  will not result in an -
unreasonable risk to health. In addition.
a State must notify the public and
provide an opportunity for a public
hearing before  a variance or exemption
is granted. Also, the State may require
that bottled water. POU devices, or POE
devices be  used as a condition for
granting the variance or exemption. In
this manner, EPA believes that public
health would have been protected where
variances and  exemptions were granted
for sulfate. To comply with today's rule.
States may update their monitoring plan
submitted under the January 1991 rule or
they may simply note in their
application that they will use the same
monitoring plan for this group of
contaminants.
  In general States may use their
discretion to schedule when, within the
overall three-year compliance period.
each system will need to perform its
one-year-long initial monitoring. For-
example. States may decide to schedule
approximately one-third of the systems '"
for monitoring during each of the three
years, to provide for an even flow of
samples through State-certified
laboratories. States will be able to
establish their own criteria to schedule
the systems to monitor but the schedules
must be enforceable under State law.
  If a State does not have primacy for
today's rule at the time the initial
compliance period begins (i.e.. January
1.1993). then EPA will be the primacy
agent. Because water systems must
monitor. EPA has established
procedures (|§ 141.23(k). 141.24(0(23).
and 141.24(h)(lB)J that require systems
to monitor at the time designated by the
State. If EPA implements today's
provisions because a State has not yet  .
adopted the regulatory requirements in
today'! rule. EPA intends to use the
State's monitoring schedule to schedule
systems during each compliance period.
EPA believes this approach will reduce
confusion over the required monitoring
schedule that might occur upon the
eventual transfer of primacy from EPA
to the State.

2. State Recordkeeping Requirements
  Some commenters characterized the
proposed recordkeepirig requirements as
burdensome and unwarranted. Similar
comments were received In reference to
the May 1989 proposed rules [54 FR
22135]. Similar comments were received
in reference to the May 1989 proposed
rules. In response to comments received
on that proposal, EPA modified the State
recordkeeping requirements to alleviate
the State burden. These changes are
explained in the January 1991 rule at 56
FR 3575. No additional changes have
been made in today's rule to the
recordkeeping requirements.
3. State Reporting Requirements

  Generally, commenters characterized
the proposed State reporting
requirements as burdensome and
useless. Similar comments were
received in response to the May 1989
proposed regulations [54 FR 22136]. In
finalizing those regulations, EPA deleted
the proposed reporting requirements
(except for unregulated contaminants),
having determined that the core
reporting requirements of the Primacy-
Rule (December 20,1988 [54 FR 52126])
would be sufficient (»ee 56 FR 3576).

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              Federal Register / Vol.  57,  No. 138  /  Friday. July 17.  1992 / Rules -and Regulations        31831
             am*mmmmi^^mmmm^^**^t**—~l~'^~''^^^-^-*'~—~l^~'^~m~m^~~~lmmmm^*^~l~^^^~'^^~~l^~^mf
 Today's mle similarly deletes the
 proposed reporting requirements and
 relies on the core reporting requirements
 of the Primacy Rule.

- IV. Economic Analysis
   In accordance with Executive Order
 12291. the Environmental Protection-
 Agency (EPA) has performed a
 Regulatory Impact Analysis (RIA) which
 is required for all "major" regulations. A
 rule is considered "major" if it is
 expected to cause:
    (1) An annual effect on the economy
 of $100 million or more:
    (2) A major increase in costs or prices
 for consumers, individual industries.
 Federal. State, or local government
  agencies, or geographic regions: or
    (3) Significant adverse effects on
  competition, employment, investment..
  productivity, innovation, or on the
  ability of the United States-based
  enterprises to compete with  foreign-
  based enterprises in domestic or export
  markets.
    An economic analysis, titled
  Economic Impact Analysis of Proposed
  National Primary Drinking Water
  Standards for 24 Inorganic and
  Synthetic Organic Chemicals (Revised
  Final) April 1990. was prepared (USEPA.
  1990c). An addendum to the EIA. dated
  May 15.1990. reclassified the rule as a
  "major" rule {USEPA. 1990a). The EIA
  indicated that national costs may
  exceed $100 million if stringent  options
  were exercised. If stringent options were
  not employed, then costs may not
  exceed S100 million and the rule may be
  classified as minor.  Another addendum
  to the EIA which revised the waste
  disposal costs for sulfate was added to
  the public docket on August 3,1990.
    Today's final rule is accompanied by
  a Regulatory Impact Analysis, titled the
  Regulatory' Impact Analysis of Proposed
  Phase V Synthetic Organic and
  Inorganic Chemical Regulations
  (USEPA. 1992dj. However, with the
  deferral of the sulfate portion of the rule.
  total costs are projected substantially
  below those shown in the Regulatory
  Impact  Analysis. The Regulatory Impact
  Analysis contains sulfate costs because
   the document was completed before the
   decision to defer sulfate was made.
     In order to estimate the economic
 -  impacts these analyses used the
   following data, where available, for
   each of the 23 contaminants:
     • Occurrence data, to determine the
   number of systems  violating MCLs;
   V • Treatment and waste disposal cost
   data and corresponding probabilities
   that systems will select each of the
   various treatment and disposal options,
   to estimate the system level and
aggregate costs of achieving the
proposed MCLs: and
  • .Monitoring costs, to estimate
aggregate costs of the monitoring
requirements.
  Occurrence data adequate to estimate
the number of systems likely to violate
the MCLs are available- for 15:of these. 23.
contaminants. For the remaining 87
contaminants (endothall. diquat. di(2-
ethylhexyl) phthalate. glyphosate.
hexachlorobenzene.
hexachlorocyclopentadiene, 1.1.2-
trichloroethane. and 2.3.7.8-TCDD) cost
impacts could not be evaluated because
national .occurrence data are not
available. In response to public
comments, impacts of the rule are not
based on extrapolation from other SOC
contaminant occurrence, as in the
proposal.
  The EIA supporting the proposed rule
estimated treatment costs for SOCs to
be Sll million per year  and also
estimated the rule would affect 900
systems. Treatment costs for JOCs
varied depending upon the MCL used for
sulfate. Treatment costs for lOCs.
estimated in the EIA dated April 1990
and modified by the Addendum dated
August 3,1990. were projected to be $60
million and to affect 1.397 systems with
a sulfate MCL of 400 mg/1. An estimated
795 systems were projected to spend
about $28 million per year to achieve
compliance with a sulfate MCL of 500
mg/1. Monitoring costs for the proposed
rule, detailed in the Information
Collection Request for: Proposed
National Primary Drinking Water
Regulations For Phase V SOCs and
lOCs [USEPA. 1989a). were estimated to
be about S8 million per year. Thus, the
total  annualized cost of the proposed
regulations were estimated to be $87
million per year with an MCL of 400 mg/
1. and $50 million per year at an MCL of
500 mg/1.
   With the receipt of new data or
 information, EPA made several changes
 to  the proposed economic analysis
 which would have resulted in an overall
 increase in the projected compliance
 costs for the final rule if sulfate has not
 been deferred. In addition, revised unit
 cost and occurrence data were
 incorporated into the final RIA. These
 changes, and their corresponding effects
 on the original cost estimates, are
 described below.

 A. Costs of the Final Rule
   Treatment and waste disposal costs
 associated with the final rule are
 estimated based on occurrence
 information available for 15 of 23
 contaminants in thi« regulation. For the
 other 8 contaminant* costs were not
 estimated because adequate occurrence
 data are not available. Monitoring and
 State implementation cost estimates
 include a consideration of all 23
 contaminants.
   Annualized total water treatment and
 waste disposal costs are  estimated at
 $31 million per year (Table 22).
.•Monitoring costs-are'eatimated.to-be •••'.'" •
 about $5 million per year. The annual
 cost to State drinking water programs to
 implement the final rule is estimated to
 be $10 million. Thus, the  total
 annualized compliance cost to the
 nation is estimated to be $46 million per
 year. Further, given the uncertainty
 associated with the inputs used to
 estimate costs for the 16  contaminants
 for which occurrence data are available
 the total annual cost of this rule could
 range from approximately $1 million to
 $128 million. These cost estimates would
 increase if the 8 contaminants for which
 costs have not currently  been estimated
 were included.
   Of the 23 contaminants covered by
 this rulemaking. endrin is the only
 contaminant regulated by an existing
 National Primary Drinking Water
 Regulation. The final MCL for endrin
 promulgated today is greater than the
 previously existing MCL. No systems
 are projected to fail the final MCL for
 endrin. Therefore, no incremental costs
 of meeting the new MCL are anticipated.
 However, costs associated with
 regulating the other 22 contaminants in
 this rulemaking do represent an
 increased cost burden.
   Table 23  shows the benefits of today's
 rule. Most contaminants are being
 regulated on the basis of non-
 carcinogenic effects. Five contaminants
 are being regulated on the basis of their
 carcinogenicity. These are:
 dichloromethane. benzo{a)pyrene, di(2-
 ethylhexyl)phthalate,
 hexachlorobenzene, and 2,3,7.8-TCDD.
 Insufficient occurrence data were
 available to estimate the number of
 cancer cases avoided for these
 contaminants. For the regulated
 contaminants that are not carcinogens,
• the adverse effects associated with
 exposure are discussed in both the
 proposed rules and these final rules.
 under the portions of the preamble that
 describe derivation of the MCLGs. The
 benefits of reduced exposure to these
 contaminants relates to  reducing the
 •possibility that water consumers may
 experience these adverse effects. For
 example, antimony caused shortened
 life spans, weight loss, increased
 cholesterol levels, and reduced blood
 glucose levels in test animals. The
 possibility of any of these effects
 occurring in exposed population* would
 be reduced by reducing  antimony
 exposure to below the MCL.

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31832
Federal Register / VoL  57. No. 138  / Friday. July 17. 1992 /  Rules and Regulations

                  TABLE 22.—SUMMARY OF COST ESTIMATES FOR FINAL RULE
! Best estimate

Cost m m&ioof of Dollars






	 1 256
	 :..! 238
	 	 	 • 14
! 30
	 I 5
!
1 46
i
Low estimate High estimate
30 795
2 925
<1 65
. . 1 • 128
N/A N/A
N/A N/A4
1 128
                              TABLE 23.—SUMMARY OF BENEFITS ESTIMATES FOR FINAL RULE
                                                                        j   Best estimate
                                                                            Low-estimate
                                                                                           HK|h estimate
Ben«l,',j ($ Millions);





340
'0.0

j
4l
N/A 1

1.729
N/A

    ' Ol tho five carcinogenic contaminants regulated m this package, occurrence data are only available tot dichlorometnane. and these data indicate that MCL
eicvtdaoces ue unlikoly Tha estimate here does not mdude the other 4 carcinogens, nor does it reflect the (act that other contaminants m this package are group
"C" possible human carcinogens, but are not being regulated on the basis ol carcmogenicity.
B. Comparison to Proposed Rule
  The costs and benefits of today's final
rule are compared to those estimated for
the proposal (Table 24). The differences
in the cost estimates are attributable to
a variety of changes in the rule and in
the available Input data used in the
analysis. Among the more important
changes are the following.
1. Monitoring Requirements
  The Agency has developed a
standardized monitoring framework
(SMF) to address the issues of
complexity, coordination of monitoring
requirements between various
regulations, and synchronization of
monitoring schedules. The monitoring
requirements in  today's rule are
somewhat different from those included
In the proposed rule, resulting in
reduction in annual national monitoring
costs of approximately $1 million, for all
contaminants, excluding sulfates. The
estimated monitoring cost of the final
rule is SS million annually.  .
                            In this regulation. EPA is requiring
                          that initial monitoring begin in the first
                          compliance period after the
                          promulgation date for systems having
                          150 or more service connections. The
                          initial monitoring period for these
                          systems is from January 1,1993 through
                          December 31.1995. For systems with
                          fewer than 150 service connections,
                          initial monitoring is from January 1.1996
                          to December 31.1998. All systems must
                          monitor at the base monitoring
                          frequency unless a waiver is obtained.
                          Systems may decrease monitoring from
                          the base requirement upon receiving a
                          waiver  from the state. In cases of
                          deteotion  or noncompliance, EPA has
                          specified increased monitoring
                          frequencies.
                          2. Changes in MCLs
                            Several MCLs in the final rule have
                          changed from those that were proposed.
                          As  discussed above, regulation of
                          sulfate  has been deferred and no final
                          MCL has been set. The MCL for di(2-
                          ethylhexyljadipate is more stringent
                          based on  a new health study which
resulted in a revised reference dose. The
MCL for 2,3,7.8-TCDD changed from 5 X
10"8 mg/Ho 3 X 10"*.mg/l because of
recently available analytic chemistry
data and the MCL for di(2-
ethylhexyl)phthalate changed from 0.004
mg/1 to 0.006 mg/1 based on
.reevaluation of the chemistry data. The
MCL for beryllium was revised from
0.001 mg/1 to 0.004 mg/1 based on public
comments and because there are
inadequate data to justify the more
stringent proposal. The MCL for 1,2,4-
trichlorobenzene was revised because
EPA agrees with public comments that
the oral RfD should not be based on an
inhalation study, particularly because
insufficient pharmacokinetic data are
available for route-to-route
extrapolation, changing from 0.009 mg/1
to 0.07 mg/1. The MCL for antimony was
revised based on a reassessment of the
relative source contribution, and
simazine was revised based on new
health effects data which allowed
elimination of an uncertainty factor
included to account for a data gap.
                           TABLE 24.—COMPARISON OF COSTS FOR PROPOSED AND FINAL RULES
                                                 [Dollar Figures in Minions]
-
Contaminants
Suttatt (400 fna/fl
Swf *!t (500 mg") . , . ,.. 	 -,,-, 	 „-.,,-,,,., 	 — -
K5Gt (ExduAofl SuHito)
SOCi ffortrtog pesbottw and VQCi

MoottCOAQ COStS .....j _! _.!..,.„!..._....!. TTT 	 	 	 ....-». 	 ...

Prop
)
System affected
1 087._ 	 ......
485 	 	
310
900
2.297 	
78.703... 	 	 	 —..
54 States and
Teoilooes.
asod
ToUlcost
(annualized) S
million*
67 	 	
30 	
3 	
1 1 	 	 ;.. 	 .
£1
6 	 	 _ 	
Not esfcmated..... 	

Fm
Systems affected
N/A 	
N/A . 	 .,
207 	
49 ;_.„ 	 	 	 . 	 .
258 	 	
,78.703 	 .._»_ 	
54 States and
Twrrtories.
>al
Total cost
(armuakzed) S
millions
N/A
N/A
30
1
31
5
10


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             Federal Register / VoL  57, No. 138  /  Frida3f, July 17,  1992 / Rules and Regulations
                                                                     31833
                     TABLE 24.—COMPARISON OF COSTS FOP PROPOSED AND FINAL RULES—Continued
                                                [Doltv Figures in Millions}

Contaminants
Nation* wfMtato eo« (SMfY'V ; 	 '. ,, , 	 	 , ,
--
Prop
Systems •Heeled


osed
Total cost
(annuateed) J
millions
87 	

Fir
Systems affected


ul
Total cost
(anouataed) S
ml Ions
AM

   Note: Totals may not tally due to independent rounding. MCLs of 400 mg/l and 500 mg/l were proposed for sutfate.
3. Changes in Occurrence Data
  Some occurrence data used in the
final RIA have been changed. A re-
evaluation of the National Inorganics
.and Radionuclides Survey data resulted
in revised antimony occurrence
estimates and estimates of systems
exceeding the MCL The number of
systems estimated to exceed the
beryllium MCL changed as a result of
MCL changes. Further review of the EPA
occurrence document resulted in a
revised occurrence estimate for
dichloromethane. For di{2-
ethylhexyl)adipate, the occurrence
estimate has been changed to reflect a
re-evaluation of available occurrence
data and a change in the MCL For 8
contaminants (endothall, diquat, di(2-
ethylhexyl) phthalate, .glyphosate.
hexachlorobenzene.
hexachlorocyclopentadiene, 1,1.2-
trichloroethane, and 2,3.7,8-TCDD)
adequate data are not available. In the
EIA accompanying the proposed rule.
approximately 82 systems were
assumed to fail the MCL for each
contaminant and to be required to
install treatment equipment. EPA
currently believes that there are
inadequate data with which to estimate
number of systems exceeding the MCL*
for these contaminants and that an
estimate of 82 systems for each
contaminant is potentially inaccurate.
While EPA is unable to estimate the
number of systems potentially
exceeding the MCL it in recognized that
an unknown number of systems may be
required to install treatment for each
contaminant.

4. Changes in Unit Treatment Cost
Estimates

  The differences between unit
treatment costs in today's rule and in
the proposed rule are due to differences
in the treatment alternatives included,
the assumed percentage of production
flow treated, and the discount rate used
in annualizing capital costs. Capital
costs in the proposed rule were
annualized over 20 yean at a 10%
interest rate to derive annual costs. The
3% interest rate used in today's final rule
was selected in order to make the costs
of the Phase V regulations comparable
to cost estimates prepared for earlier
rules.

C, Cost to Systems

  Table 25 indicates that relatively few
water systems and consumers will be
affected by the regulations. However,
costs will vary depending upon the
specific chemical contaminant and the
size of the public water system.
  Systems serving 500 or less people
will incur higher per household costs
because they do not benefit from
engineering economies of scale.
Households served by these systems
would have to pay significantly more.
should their system have contamination
greater than the MCL.
                    TABLE 25.—INCREASED COST OF COMPLIANCE IN SELECTED SYSTEM S'IZE CATEGORIES
System Scze ! 25-100
Contaminant
Antimony
Nickel 	
Dicnioromettv
ane 	
Dinoseb 	

Annual
Cost per
Household
13.651
1,747
353
984
Cost per
System
$49.500
25.000
4.400
12.500
Number
of
Systems
es
4
18
4
101-600
Annual
Cost per
Household
$1.721
717
138
343
Cost per
System
$102.800
43.300
7.300
20,000
Number
of
Systttms
57
3
11
3
3.301-10.000
Annual
Cost per
Household
$274
0
12
0
Cost per
System .
$521.000
0
2S.OOO
0
Number
of
Systems
10
0
2
0
25.001-50.000
Annual
Cost per
Household
$137
0
0
0
Cost per
System .
$1.935,000
0
0
0
Number
of
Systems
2
0
0
0
    Note: For systems serving over 1,000.000 people, no MCt excoedance or cost is estimated.
D. Cost to State Programs
  In 1988, EPA and the Association of
State Drinking Water Administrators
(ASDWA) conducted a survey of State
primacy program resource needs for
implementing the 1988 SDWA
amendments. State implementation
costs for the Phase V rule were not
included in the ASDWA survey. State
implementation costs of previously
regulated Phase II inorganic and
synthetic organic chemicals are
estimated to be $21 million during the
initial phase. An additional $17 million
is estimated to be required for States to
annually conduct enforcement actions,
assist in the expansion of laboratory
capabilities, and manage compliance
schedules. Laboratory expansion
undertaken to implement Phase n
regulations will largely satisfy the
monitoring needs of this rule. Total State
implementation coqts are anticipated to
be in the range of $7 million to $12
million. A gross point estimate of $10
million pet year has been selected for
today'* final rule.'
V. Other Requirements

A. Regulatory Flexibility Analysis

  The Regulatory Flexibility Act
requires EPA to consider the effect of
regulations on small entities [5 U.S.C.
602 et seq.]. If there is a significant
economic effect on a substantial number
of small entities, the Agency must
prepare a Regulatory Flexibility
Analysis (RFA) describing significant
alternatives that would minimize the
impact The Agency had determined that
the proposed rule, if promulgated would
not have a significant economic impact

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31834        Federal  Register / Vol.  57.  No. 138 / Friday.  July  17.  1992 / Rules and Regulations
on a substantial number of small
entities.
  According to EPA guidelines for
conducting RFA assessments, less than
20 percent of a regulated population is
not considered a substantial number.
The RFA for the final rule indicates that
of 77.910 community and non-transient
non-community water supplies serving"
50.000 or fewer people, about 253 (<1
percent) are estimated to exceed the
final MCLs promulgated in today's rule.
Therefore, today's rule does not  affect a
substantial number of such small
systems.
  Compliance costs for the 253 systems
serving 50.000 or fewer people required
to install treatment are about S31 million
per year for capital and operational
maintenance. This is less than one
percent of the  total national operating
expense for such systems. Therefore, at
a national aggregate level, the Phase V
rule would not have a significant impact
on small systems. This finding does not
change if the costs of monitoring to
these systems, S6 million per year, are
included.
 "The Agency's determination of no
significant economic impact on a
substantial number of small systems
would remain  unchanged under a more
stringent definition of small systems.
Defining systems serving 3.300 or fewer
people as small, today's rule would
affect 235 of the 65.766 public systems in
this size category. This represents less
than one percent of such systems. Costs
would increase S16 million, or
approximately one percent of the total
operating expense for all systems in this
category. The inclusion of monitoring
costs of less than S4 million for such
systems does not alter this finding.
  EPA's determination of no significant
economic impact on a substantial
number of small systems would likely
also remain the same if occurrence data
on the eight contaminants not currently
included in this analysis became
available. While it is not possible to
estimate the number of systems
exceeding the  MCLS for these
contaminants  the number is potentially
small as these contaminants have rarely
been found in  drinking*water.
  Although there will not be a
significant economic impact on a
substantial number of small systems on
the whole, a small number of individual
systems may find their costs increasing
sharply, depending on the specific
contaminant in their water. For
example, it can be seen from Table 25
that a system serving 25-100 people with
antimony-contaminated water is
expected to incur additional annual
costs of $49,500. EPA is concerned about
such systems.  Under the Safe Drinking
 Water Act small systems may obtain an
 exemption for national primary drinking
 water regulation requirements if they
 can demonstrate that the granting of the
 exemption would not result in an
 unreasonable risk to health, among
 other conditions. Other aspects of the
 regulatory scheme that serve to reduce
 impacts on small systems are described
 in the proposal (55 FR 30436) and earlier
 in this notice.
 B. Paperwork Reduction Act

  The information collection
 requirements in this rule have been
 submitted for approval to the Office of
 Management and Budget (OMB) under
 the Paperwork Reduction Act [44 U.S.C.
 3501 et seq.]. These requirements are not
 effective until OMB approves  them and
 a technical amendment to that effect is
 published in the Federal Register.
  Public reporting burden for this
 collection of information is estimated to
 average  0.6 hours per response for
 public water systems and 13.6 hours for
 States to compile each response. These
 estimates include time for reviewing
 instructions, searching existing data
 sources, gathering the information
 needed,  and completing and reviewing
 the collection of information as well as
 start-up  activities such as staff training.
 Comments regarding the burden
 estimate of any other aspect of this
 collection of information, including
 suggestions for reducing this burden.
 should be sent to Chief. Information
 Policy Branch. PM-223Y. U.S.
 Environmental Protection Agency, 401 M
 Street, SW.. Washington. DC 20460; and
 to the Office of Information and
 Regulatory Affairs, Office of
 Management and Budget, Washington.
 DC 20503, marked "Attention: Desk
•Officer for EPA."
 C. Federalism Review

  Executive Order 12612 requires all
 federal agencies to consider legislative
 and regulatory proposals and other
 major policy actions to determine if they
 have substantial effects on federalism
 goals and principles  as-set forth in the
 Executive Order. According to EPA's
 Guidelines for Implementing Executive
 Order 12612: Federalism, "[i]f an EPA
 action is mandated or the necessary
 means to carry it out are implied by
 statute, then no further, federalism
 assessment is required." Twenty-two of
 the 23 contaminants  regulated today are
 included in the list of 83 contaminants
 for which EPA is required to promulgate
 National Primary Drinking Water
 Standards. Therefore, a federalism
 assessment is not required to support
 this  rule  for these listed contaminants.
   For hexachlorobenzene, which is not
 on the list of 83 contaminants, a
 federalism assessment is not required
 because today's regulation will not have
 a substantial direct effect on States, the
 relationship between the Federal
 Government and the States or on the
 distribution of power, and  •.
 responsibilities among the various levels
 of government.

 VI. References

 40 CFR Part 136. Appendix A

 40 CFR Part 136, Appendix B
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Co^ey. ]. el al 1985, Reference Doses (RfDs)
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   Molybdenum. Nickel, Cobalt. Vanadium.
   and Strontium in Total Diets. Division of
   Nutrition and Division of Contaminants
   Chemistry. Center for Food Safety and
   Applied Nutrition. Food and Drug
   Administration, Washington. D.C. In:
   Journal of the American Dietetic
   Association. Vol. 87. No. 12. December
   1987. pp. 1644-1650. [Pennington and Jones,
   1987]
 Philbrick. D.J.. J.B. Hopkins. D.C. Hill. J.C.
   Alexander and  R.G. Thomson. 1979. Effects
   of Prolonged Cyanide and Thiocyanate
   Feeding in Rats. J. Toxicol. Environ. Health.
   5:579-592. [Philbrick et al.. 1979]
 Reyna. MS. 1990. Two Generation
   Reproduction Feeding Study with
   Glyphosate in Sprague-Dawley Rats.
   Monsanto Agricultural Company. August
 '  27,1990. MRID «416215-01. [Reyna. 1990]
 Robeck. C.G. 1978. Health Effects of PAHs.
   Memorandum to J. Gamer. Director. Health
   Effects Research Laboratory, USEPA.
   Washington. DC. Cited in NAS, 1982.
   [Robeck. 1978]
 Robinson  Kathy S.. Robert J. Kavlock. Neil
   Chemoff. and L. Earl Gray. 1981.
   Multigeneration Study of 1.2.4
   Trichlorobenzene in Rats. J. Toxicol.
   Environ. Health. 6:489-500. [Robinson et al.,
   1981]-                      }
 Sanders. V.M., K.L White. G.M. Shopp and
   A.E. Munson. 1985. Humoral and Cell-
   Mediated Immune Status of Mice Exposed
   to 1.1,2-Trichloroethane. Drug Chem.
  Toxicol. 8:357-372. [Sanders et al.. 1985]
 Saxena. J., DJC. Basu and D.J. Schwartz. 1978.
  Method Development and Monitoring of
  Polynuclear Aromatic Hydrocarbons in
  Selected U.S. Waters, pp. 119-126. in ].
  Albaiges, ed.. Proceedings of the
  International Congress Analytical
  Techniques in Environmental Chemistry,
  Barcelona, Spain, Nov. 27-30,1978.
  Pergamon Press. N.Y. [Saxena et al, 1978]
Schroeder. HJV., M. Mitchener and A-P.
  Nasor. 1970. Zirconium. Niobrium.
  Antimony, Vanadium and  Lead in Rats;
    Lifetime Studies. J. Nutr. 100:59-66.
    |Schroeder et al.. 1970]
  Seattle Distribution System Corrosion
    Control Study. 1981. Volume III: Potential
    for Drinking Water Contamination from
    Tin/Antimony Solder. Prepared by Hen-era
    et al. Seattle Dept. of Water. Seattle. WA.
    Prepared for Municipal Environmental
    Research Lab. Cincinnati, OH. [Seattle.
    1981] • -   '
  Serota. D.G.. A.K. Thakur. B.M. Ulland. J.C.
    Kirschman, N.M. Brown and R.H. Coots.
    1986a. A Two-Year Drinking-Water Study
    of Dichloromethane in Rodents. I. Rats.
 •  Food Chem. Toxicol. 24:951-958. [Serota el
    al.. 1986a]
 Serota. D.G.. A.K. Thakur. B.M. Ulland. J.C.
    Kirschman. N.M. Brown and R.H. Coots.
    1986b. A Two-Year Drinking-Water Study
    of Dichloromethane in Rodents. II. Mice.
    Food Chem. Toxicol. 24:959-963. [Serota et
   al., 1986b]
 Sorrell. R.K.. H.J. Brass and R. Reding. 1980. A
   Review of Occurrences and Treatment of
   Polynuclear Aromatic Hydrocarbons.
   Environ. Int. 4:245-254. [Sorrell et al.. 1980]
 Speth. Thomas S. 1990. The Removal of
   Glyphosate from Drinking Water. [Speth.
   1990]
 Speth. Thomas S. 1991. The Removal of
   Glyphosate from Potable Waters. DWRD.
   Cincinnati, OH. (Speth. 1991]
 SRI. 1981. Southern Research Institute.
   Subchronic Toxicity Report on
   Hexachlorocyclopentadiene (C53607) in
   Fischer-344 Rats. Unpublished Report for
   NTP. 144 pp. [SRI, 1981]
 Stoltz. M.L.. MA. Stedham. LK. Brown. L.
   Laber and A. Elhawari. 1986. Subchronic
   (90-day) Toxicity of Thallium (I) Sulfate in
   Sprague-Dawley Rats. U.S. EPA. Office of
   Solid Waste,  Washington. DC (Sloltz et al..
   1986]
 Stout. LD'. and FA Ruecker. 1990, Chronic
   Study of Glyphosate Administered in Feed
   to Albino Rats. Monsanto Environmental
   Health Laboratory. Monsanto Company
   September 28.1990. MRID *416438-01.
   [Stout and Ruecker. 1990)
 Subramanian. K.S.. J.W. Connor and J.C.
   Meranger. 1991. Leaching of Antimony.
   Cadmium, Copper. Lead. Silver. Tin and
   Zinc from Copper Piping With Non-Lead-
   Based Solder Joints. J. Environ. Sci. Health
   A26(6).-911-929. [Subramanian et al.. 1991]
 U.S. EPA. 1983. Method for Chemical
   Analysis of Water and Wastes. [USEPA.
   1983]
 U.S. EPA. 1986. U.S. Environmental Protection
   Agency. Guidelines for Carcinogen Risk
   Assessment. Federal Register.
   51(185):33992-34003. [USEPA. 1986|
 U.S. EPA. 1987a. Guidelines for Delineation of
   Wellhead Protection Areas. Office of
  Ground-Water Protection. U.S.
  Environmental Protection Agency. EPA-
  440/6-87-010. 220 pp. [USEPA. 1987a]
U.S. EPA. 1987b. Method 200.7, Appendix.
  "Inductively Coupled Plasma. Atomic
  Emission Analyses of Drinking Water."
  Rev. 1J (March. 1987). [USEPA. 1987b|
U.S. EPA. 19888. Impact of Lead and Other
  Metallic Solders on Water Qual.ty.
  Prepared by N-E. Murrell for USEPA. July
  28.1988. 96 pp. [USEPA. 1088ai

-------
U.S. EPA. 1988b. Final Draft for Drinking
  \Vater Criteria Document on Cyanide.
  Environmental Criteria and Assessment
  Office. Office of Health A Environmental
  Assessment. Sept. 1988. (USEPA. 1988bl
U.S. EPA. 1988c. Final Draft for Drinking
  Water Criteria Document on Polycydic
  Aromatic Hydrocarbons. ECAO,
  Cincinnati. (ECAO-CIN-D010). Sept. 1988.
        .
 U.S. EPA. 1988d. Batemal Review Dr«* fw
   Drinking Water Criteria Document for
   2.3, 7.3- TetrachIorodib*nmo-P:Dioxin.
   Environmental Criteria and Assessment
   Office. Office of Health and Environmental
 •  Assessment. April. 1908. 361 pp. [USEPA.
   1988d|
 U.S. EPA. 1988e. "Methods for the
   Determination of Organic Compounds in
   Drinking Water." Environmental
   Monitoring Systems Laboratory. Cincinnati,
   OH 4S268 (1988). EPA/600-4-88/039
   (USEPA, 1988e]
 U.S. EPA. 1988f. Report to Congress.
   Availability. Adequacy, and Comparability
   of Testing Procedures for the Analysis of
   Pollutants Established Under Section
   304(h) of the Federal Water Pollution
   Control Act. Environmental Monitoring
   Systems Laboratory. Cin.. September 1988.
   EPA/600/9-S7/030. [USEPA. 1988f]
 U.S. EPA. 1989a. Information Collection
   Request for: Proposed National Primary
   Drinking Water Regulations for Phase V
   SOCs and lOCs (Final). Prepared by Wade
   Miller Associates for U.S. EPA. Office of
   Drinking Water. Sept. 28, (USEPA. 1989al
 U.S. EPA. I989b. Occurrence and Exposure
   Assessment of Hexachlorobenzene in
   Public Drinking Water Supplies. Office of
   Drinking Water. May 15.  1989. [USEPA.
   1989b]
 U.S. EPA. 1989c. Method 200.8,
   "Determination of Trace  Elements in
   Waters and Wastes by Inductively
   Coupled Plasma /Mass Spectrometry,"
   Environmental Monitoring Systems
   Laboratory. Cincinnati, OH 45268 (Sep.,
   1989). 44 pp. [USEPA. 1989c]
  U.S. EPA. 1989d. Method 300.0, "The
   Determination of Inorganic Anions in
   Water by Ion Chromatography,"
   Environmental Monitoring Systems •
    Laboratory, Cincinnati. OH 45268 (Dec.,
    1989). 20 pp. [USEPA. 1989d]
  U.S. EPA. 1990a. Addendum to Economic
    Impact Analysis of Proposed. National
    Primary Drinking Water Standards for 24
    Inorganic and Synthetic Organic
    Contaminants (Revised Final) April 1990.
    Transmittal memo from  Betsy Tarn, Office
    of Drinking Water to Phase V Rule Public
    Docket File. Aug. 3, 1990. 9 pp. [USEPA,
    1990a]
   U.S. EPA. 1990b. Criteria and Standard*
    Division, Office of Drinking Water.
    Technologies and Costs for the Removal of
    Phase V Inorganic Contaminants from
    Potable Water Sources. January. 1990. 95
    pp. [USEPA. 1990b|
   U.S. EPA. 1990c. Ecsnomic Impact Analyiii
     of Proposed National Primary Drinking
     Water Standards for 23 Inorganic and
     Synthetic  Organic Chemicals (Revised
     Final) April 1990. [USEPA. 1990cJ
   U.S. EPA. 1990d. Final draft for Drinking
     Water Criteria Document on Antimony.
  Dynamac Corporation, for Criteria and
  Standards Division. ODW. EPA. April.
  1990.96 pp. [USEPA. ISQOd]
U.S. EPA. 1990e. Final draft for Drinking
  Water Criteria Document on Diquat
  Dynamac Corporation, for Criteria and
  Standards Division. ODW. EPA. April.
  1990.92 pp. [USEPA. 1990el
U.S. EPA. 1990f. Final draft for Drinking
  Water Criteria Document m Glyphosat*
  Dynamac Corporation, for Criteria and
  Standards Division. ODW. EPA. April.
  1990. 56 pp. (USEPA. 1990f)
U.S. EPA. 1990g. Final draft for Drinking
  Water Criteria Docum«nt on Thallium.
  Dynamac Corporation, for Criteria and
  Standards Division. ODW. EPA. April.
  1990.105 pp. [USEPA. 'iggOg)
U.S. EPA. 1990h. Method Detection Limit
  (MDL)  Study for Method 1613
  Determination of 2J.7.S-TCDD and 2.3.7.8-
  TCDF. July 1990. [USEPA. 1990h]
U.S. EPA. 1990i. National Survey of Pesticides
  in Drinking Water Weils. Phase 1 Report.
  EPA-570/9-90-05. Office of Water. Office
  of Pesticides and Toxic Substances.
  November 1990. [USEPA. 1990i|
U.S. EPA. 1990). Transcript: Public Hearing.
  National Primary and Secondary Drinking
  Water Regulations: Proposed  Rule.
  Washington,  D.C. Tuesday. September 25,
  1990. [USEPA. 1990JJ
U.S. EPA. 1990k. "Methods for the
  Determination of Organic Compounds in
  Drinking Water." Supplement One.
  Environmental Monitoring  System*
  Laboratory. Cincinnati. OH 45268 (1990).
  EPA/600-4-90/020 [USEPA. 1990kJ
 U.S. EPA. 19901. Method 1613, 'Tetra-through
  Octa-Chlorinated Dio:cins and Furans by
  Isotope Dilution HRGC/HRMS. Office of
  Water Regulations and Standards.
  Industrial Technology Division (1990). 46
   pp. (USEPA.  19901]
 U.S. EPA, 1990m. Manual for the Certification
   of Laboratories Analyzing  Drinking  Water.
   Criteria and Procedures Quality
   Assurrance. 3rd ed. El?A/570/9/9-90/008.
   [USEPA. 1990m]
 U.S. EPA. 1991a. Lead and Copper  in Drinking
   Water as a Result of Corrosion: Evaluation
   of Occurrence. Cost, and Technology.
   Criteria and  Standards Division. Office of
   Drinking Water. April 1991. 238 pp.
   [USEPA. 1991a]
 U.S.  EPA. 199lb. Memorandum from Charles
   Abernathy to HRAB Staff. Report on
   December RTD/R/C Workgroup Meeting in
   RTF. [USEPA. 199lb]
  U.S. EPA. 1991c. Multilaboratory Method
   Validation Study Data. National Pesticide
   Survey (NPS). 1991. [USEPA. 1991c] .
  U.S. EPA. 199ld. Water Supply (PE) Studie*
   21-27 (study number varies based on
   contaminant). 1991. [USEPA. 199ld]
  U.S. EPA. 1991e. Protecting The Nation'*
   Ground Water EPA'« Strategy for th«
   1990's. The Final Report of the EPA
   Ground-Water Task Force. Office of the
   Administrator. 21Z-1020, July 1981.
    (USEPA. 1991e] (.
  U.S. EPA. I991f. Drinking Water Criteria
    Document for Polycydic Aromatic
    Hydrocarbons (PAHu). Environmental
    Criteria & Assessment Office. Office of
    Health * Environmental Assessment.
    December 1991. [USEPA,  199lf]
U.S. EPA. 1931%. Drinking Water Criteria
  Document for Phthalic Acid Esters (PAEs).
  Environmental Criteria & Assessment
  Office. Office of Health & Environmental
  Assessment. August 1991. [USEPA. 1991 gj
U.S. EPA. 1991h. Managing Ground Water
  Contamination Sources in Wellhead
  Protection Areas: A Priority Setting
  Approach. EPA Office of Water. EPA-S'O/. • ...
  9-91-023. [USEPA. 19Blhl
U.S. EPA. 1991i. Methods for the
  Determination of Metals in Environmental
  Samples. Environmental Monitoring
  "Systems Laboratory. 1991. EPA/600/4-fll/
  010
U.S. EPA. 1992a. Comment/Response
  Document for Phase V contaminants.
  Office of Ground Water and Drinking
  Water. May 1992. [USEPA, 1992a]
U.S. EPA. 1992b. Final Drinking Water
  Criteria Document for Glyphosote. Office
  of Science and Technology. Office of
  Water. January 1992. [USEPA. 1992b]
U.S. EPA. 1992c. Final Drinking Water
  Criteria Document for Thallium. Health &
  Ecological Criteria Division. Office of
  Science & Technology. Office of Water.
  January 1992. [USEPA. 1992c]
U.S. EPA. 1992d. Regulatory Impact Analysis
  of Proposed Phase V Synthetic Organic and
  Inorganic'Chemicals Regulations. February
 . 1992. [USEPA. 1992d]
 U.S. EPA. 1992e. Technologies and Cost* for
  the Removal of Phase V Synthetic Organic
  Chemicals  from Potable Water Supplies.
  Drinking Water Standards Division. Office
  of Ground Water and Drinking Water. May
  1992. [USEPA. 1992e]
 U.S. EPA. 1992f. Final Drinking Water
  Criteria Document for Antimony. Health ft
 . Ecological  Criteria Division, Office of
   Science * Technology. Office of Water.
   January 1992. [USEPA. 1992fJ
 U.S. EPA. 1992g. Final Drinking Water   •
   Criteria Document for Diquat.  Health *
   Ecological  Criteria Division. Office of
   Science & Technology, Office of Water.
   January 1992. [USEPA. 1992g]
 U.S. EPA. 1992h. Drinking Water Criteria
   Document  for Cyanide. Health & Ecological
   Criteria  Division. Office of Science &
   Technology, Office of Water. January 1992.
   [USEPA. 1992hJ
 Watanabe, P.G.. R.J. Kociba. R.E. Hefner. Jr.,
   H.O. Yake! and B.K.J. Leong. 1978.
   Subchronic Toxicity Studies of 1.2,4-
   Trichlorobenzene in Experimental Animal*.
   Toxicol. Appl. Pharmacol. 45(l):332-333.
   [Watanabe et al.. 1978]
  White. K.L,  V.M. Sanders, D.W.. Barnes,
   G.M. Shoup and A.E. Muiuon. 1985.
   Toxicology of 1,1.2-Trichloroethane in the
   Mouse. Drug Chem. Toxicol. 8:333-355.
   [White et  al.. 1985]
  World Health Organization. 1984. Guideline*
   for Drinking-Water Quality. Vol. 2. Health
   Criteria and Other Supporting Information.
   Geneva, pp. 290-292. [WHO. 1984]
  ZoJdak. J.J. 1978. Anarysi* of Drinking Water
   for Tree*  Level Quantities of  Organic
   Pollutant*. Thesi*. Miami University.
   Oxford. OH. Cited in MAS. 1982. [Zoldak,
   1S78J

-------
31838       Federal Register  /  Vol. 57. No. 138 / Friday. July 17. 1992 / Rules  and Regulations
List of Subjects In 40 CFR Parts 141 and
142.
  Administrative practice and
procedure. Chemicals. Indians-lands.
Intergovernmental relations. Radiation
protection. Reporting. reeordkeeping
requirements. Water supply.
  Dated: May 18,1992.-
F. Henry Habicht II.
Administrator.
  For the reasons set forth in the
preamble, chapter I  of title 40 of the
Code of Federal Regulations is amended
as follows:

PART 141—NATIONAL PRIMARY
DRINKING WATER  REGULATIONS

  1. The authority citation for part 141
continues to read as follows:
  Authority: 42 U.S.C. 300f. 300g-l. 300g-2.
300g-3.3008-4.300g-5.300g-6.300J-4 and
300J-9.
  2. Section 141.2 is  amended by
revising.the definition for "Initial
compliance period"  to read as follows:

§ 141.2  Definition*.
•    «    «     *    •
  Initial compliance period means the
first full three-year compliance period
which begins at least 18 months after
promulgation, except for contaminants
listed at 141.61{a) (19}-{21). (c)(19)-{33).
and 141.62(b) (11H16). initial
compliance period means the first full
three-year compliance period after
promulgation for systems with 150 or
more service connections (January 1993-
December 1995), and first full three-year
compliance period after the effective
date of the regulation (January 1996-
December 1998) for systems having
fewer than 150 service connections.
*r    *    *    *    *

  3. Section 141.6 is amended by adding
paragraph (h), to read as follows:-

5141.6  Effectlvt Date.
•   ' •    *    ,•    *

  (h) Regulations for the analytic
methods listed at . 141.23(k)(4) for
measuring antimony, beryllium, cyanide.
nickel, and thallium are effective August
17.1992. Regulations for the analytic
methods listed at 5 141(f)(16) for
dichloromethane, 1.2,4-trichlorobenzene,
and 1,1.2-trichloroethane are effective
August 17,1992. Regulations for the
analytic methods listed at § 141.24(h)(12)
for  measuring dalapon. dinoseb, diquat.
endothall, endrin. glyphosate. oxamyl,
picloram. simazine. benzo(a)pyrene,
di(2-ethylhexyl)adipate. di(2-'
ethylhexyljphthalate,
hexachlorobenzene.
hexachlorocyclopentadiene, and 2.3,7,8-
TCDD  are effective August 17,1992. The
revision to  5 141.12(a) promulgated on
July 17.1992 is effective on August 17.
1992.
  4. Section 141.12 is amended by
removing and reserving paragraph (a) in
the  table to read as follows:

S 141.12 Maximum contaminant leveta for
organic chemical*.
   (a) [Reserved)
 •    *    *    •    •
   5. Section 141.23, which will be
 effective, is amended by revising the
 introductory text to paragraph (a)(4). by
 revising the introductory text to a
 (a)(4)(i), (a)(4)(i) table, by adding
 paragraph (a)(4)(iii). by. revising-
 paragraph (c) introductory text. (c)(l).
 and (i)(l). by redesignating (k)(5) as
 (k)(6) and revising it, redesignating (k)(4)
 as (k)(5) and revising it, and by adding a
 new (k)(4) to read as follows:

 § 141.23 Inorganic chemical sampling and
 analytical requirements.
 •    •,    •     •   _ •
  (a) *" * .'
  (4) The State may reduce the total
 number of samples which must be
 analyzed by allowing the use of
 compositing. Composite samples from a
 maximum of five samples are allowed.
 provided that the detection limit of the
 method used for analysis is less than
 one-fifth of the MCL. Compositing of
 samples must be done in the laboratory.
  (i) If the concentration in the   •
 composite sample is-greater than or
 equal to one-fifth of the MCL of any
 inorganic chemical, then a follow-up
 sample must be taken within 14 days at
each sampling point included in the
composite. These samples must be
analyzed for the contaminants which
exceeded one-fifth of the MCL in the
composite sample. Detection limits for
each analytical method and MCLs for
each inorganic contaminant are the
following:
                                    DETECTION LIMITS FOR INORGANIC CONTAMINANTS
Conlirrur.im



A3&0S10S _«_ «« ....... .,
Banum , . _«.*<, »»* ,<_._..,


8Mass Spectromotry . . . 	


Atomic Absorption* (umac* tecfirwQue 	 «.: 	
Atomic Absorptxyv <1*r8C1 •spraixxi 	 '......
Inductively Goopted Plasma . . 	 	
Atomic Absorption; Furnace 	 	 	 ,...,„..,...,„ 	 	 	 	 	 	 	 	 '.... .
xi 	 „ 	 _ 	 _ 	 _ 	 _ 	 _ 	
Inductively Coupted Plasma ' . ___ 	 _. .. _._ 	 _ 	 	 	 	
ICP-Mass Sp-ctrometry . .. 	 	 _ 	 _ 	
Atomic Absorption; furnace technique 	
Inductively Coupled Plasma 	 	 - 	 - 	 „ 	 	 	 	 	
Atomic Absorption* furnace technique . .. 	 - 	 - 	 - 	 -
Inductively Coupled Plasma.... 	 ..„_ 	 /. 	 .+ 	 _ 	 	 	 _ 	 _ ..
Distillation. Spectropnotomctric 4
Distillation Automated Spectrophotometric * 	 - 	 « 	 	 	 _ 	
Distillation, S«tectiv« Electrode * 	 	 	 	 	 	 	
Destination, Amentbte. Spectroptiotomfllnc * .. 	 	 , . T 	 	 	 „ 	
Manual Cold Vapor Technique 	 ___._._. 	 _„_. 	 ......._„__ 	 __.._„„__ 	 	 	 .___.._ 	
Aual"Kl CoW Vapof Technique ........ ..._ 	 _ 	 	 	
Atomic Absorption; Furnace . .. _ _.. .«.._ . . _ 	 j. . . 	 ....
Inductively Coupted Plasma *. 	 -•• 	 -• ... 	 _.'._'._ 	
ICP-Mtss Spectromelry. 	 	 	 	 	 	 -.. 	 - 	 _ 	 •.„ 	 _ 	 	 	 	
Detection
limit (mg/l)
0003
0.0008'
0.0004
0.001
0.01 MFL
0.002
0.1
0.002
(0.001) '
0.0002
0.00002"
0.0003
0.0003
0.0001
0.001 '
0.001
0.007
(0.001) '
0.02
0.005
005
0.02
0.0002
0.0002
0.001
00006*
0.005
0.0005

-------
                                DETECTION LJMJTS FOR INORGANIC CONTAMINANTS—Continued
    Contaminant
   MCL
  (mg/l)
                                                                 Methodology
                                                                                              Detection
                                                                                             limit (mg.'i)
Nitrate,
10 (as N)..i Manual Cadmium Reduction	
        I Automated Hydrazine' Reduction..
        | Automated Cadmium Reduction...
        i Ion Selective Electrode	
                                                                                            .; 0 01
                                                                                              0.01
                                                                                            ...: O.OS
NHtme	 1 (as I
                            Ion Crwomatograpny..
!
Selenium

Thallium
j 0.05
                           i Automated Cadmium Reduction...
                           ; Manual Cadmium Reduction .........
                           : Ion Chr'omatOQfaphy ....... . ..............
                            Atomic Absorption: lumace
          Atomic Absorption; gaseous hydnde...
! 0.002	 Atomic Absorption: Furnace	
                            CP-Mass Spectrometry...
                                                                                          ...j 0.01  ,
                                                                                          ..... 0.01
                                                                                          ..... 0.05
                                                                                          ....; o.oi
                                                                                          .... 0.004
                                                                                          ..... 0.002  •
                                                                                          ....) 0.002
                                                                                          ....I 0.001
                                                                                            I 0.0007 «
                                                                                          .... 0.0003
    1 Us:r>g concentration technique in Appendix A to EPA Method 200.7.
    «MFL = miUion fibers per liter > 10 ^m.                          — •
    ' Using a 2X preconcentration step as noted m Method 200.7. Lower MDLs may be achieved when using • 4X preconcentration.
    • Screening metnod for total cyanides.
    ' Measures "free" cyanides.
    " Lower MDLs are reported using stabilized temperature graphite lumace atomic absorption.
   (iii) If duplicates of the original
sample taken from each sampling point
used in the composite are available, the
system may use these instead of
resampling. The duplicates must be
analyzed and the results reported to the
State within 14 days of collection.
«     •     *     •    •

   (c) The frequency of monitoring
conducted to  determine compliance with
the maximum contaminant levels in
1141.62 for antimony, barium, beryllium.
cadmium, chromium, cyanide, fluoride,
mercury, nickel, selenium and thallium
shall be as follows:
                         (1) Groundwater systems shall take
                       one sample at each sampling point once
                       every three years. Surface water
                       systems {or combined surface/ground)
                       shall take one sample annually at each
                       sampling point.
                       •    •     •    •    •

                         (i) *  ' *
                         (1) For systems which are conducting
                       monitoring  at a frequency greater than
                       annual, compliance with the maximum
                       contaminant levels for antimony.
                       asbestos, barium, beryllium, cadmium.
                       chromium, cyanide, fluoride, mercury,
                       nickel, selenium  and  thallium is
                       determined by a  running annual average
                                                               at any sampling point. If the average at
                                                               any sampling point is greater than the
                                                               'MCL. then the system is out of
                                                               compliance. If any one sample would
                                                               cause the annual average to be
                                                               exceeded, then the system is our of
                                                               compliance immediately. Any sample
                                                               below the method detection limit shall
                                                               be calculated at zero for the purpose of
                                                               determining the annual average.
                                                               •  •  •     •    •    •
                                                                  (k) Inorganic analysis
                                                                  (4) Analysis for the listed inorganic
                                                               contaminants shall be-conducted using
                                                               the following methods:
Contaminant






•

Beryfhum







Cyanide


Mercury _

Nickel




Vstrat«._— . 	 	 — —

•Methodogy !
Atomic Absorption; Fumac* * 	

ICP-Mass Spectrometry • . 	 	
Hydnde-Atorrac Absorption * ...

AtoTvc Absorption: Furrmc**..- 	 	 	 	
Atorruc Absorption; Direct*..- 	
Inductively Coupled Plasma * 	 _ 	 ". 	
Atomic Absorption; Furnace * 	 	
Atomic Absorption' Platform*... 	

ICP-Mass Spectrometry * 	

Inductively Coupt^d Plasma *,, 	 ,L 	 	 ...


DtstiHabon Spec .. 	 - 	

Distillation. Setectiv* Electrode 	 _ 	 _.
Distillation, Amenable. Spec. 	 	 	 	
Manual CokJ Vapor Technique • 	 - 	 = 	 	
Automated Coid Vapor Technique * 	 .. -
Atomic Absorption* Fumaot * 	 	 	 	 	 ......


tntKjcttvqfy Coupteft P1»iiTa * , , , ,
ICP-M*s» Sp8CTnxn»try • , ' 	 , ,,. ,,
Manual Cadmium Reduction 	
Aufm>t1^d Hy9 FWrJurtoo 	 	
Automated C*dmium Reduction .- 	 	
EPA ••*•»!
1 2CM.2
1 220.9
•200.8

12 EPA
i 20S.2
•208.1
'200.7
1 210.2
•2009
1 200.7
» -200.8
1 213.2
•200.7
'218.2
1 200.7
1 335.2
1 335.3

'335.1
1 245.1
1 245.2
'249.2

1 249 1
•200.7
•200.8
•353.3
' 353.1
'353.2
ASTM»



D-3697-87




D-3645-848







D-2036-69A

D-2O36-69A
D-2O36-898
D3223-66




-

D3867-90
03867-90
SM* i
3113 *




3113B
3111D
3120
3113

3120

31138

31138
3120
4500-CN-O
450O-CH-E
4500-CN-F
4500-CN-G
31128

3113

311 IB
3120' ' "

4500-NOr-e
4500-NQr-F
USGS«






'









(330085











Other

























-



-------
31840
             Federal Register /  Vok 57.  No.  138  / Friday. July 17. 1992  /  Rules and Regulations

ComarrnMnt
, — — —
Thai!wr> ...-,.<«>—.—
• "Memods ol <
| Methodogy
I
t
,.„., Spectophometnc 	
Automated Cadmium Reduction...
ion Chromatography 	 __ 	
... Hydrate-Atomic Absorption • .'.'. —
, Atomic Absorption: Furnace

, !CP-Mass Spectrometry • 	
memicaJ Analysis ol Water and Waste
	 	 I
i
	 !
	 	 i
	 !
.._ 	 i
	 	 j



EPA •• l "

' ' 300.0
'354.1
1 353.2
' 353.3
' ' 300.0.
' 270.2
' 279.2
5 200,9
•200.8
ASTM»
03867-90
03867-90
03859-88
|
SM» j USGS« ; Other
4500-NOj-F
4500-NOj-E
3113B
3113
WeWWG/
5880'
B-1011 •
B-1011"
i
1
s." EPA Environmental Momtonng Systems Laboratory. Cincinnati. OH 45263 March 1883. EPA-*OU/«-
                        ^
                                                                                                                     -
                                                   ,s



                                                                                                vapor
                                                                                                                       digestion
 U^?-%aty^J Memod For Determinate of Asbestos Fibers in Water." EPA-600/4-83-043. September 1983. U.S. EPA Environmental Research Laboratory.

 Atrwu. GA 30613,
                                                                                    ait?i »w samples.
                                                                                    Chemistry Branch. Environmental Momtonng  Systems
    (5) Sample collection for antimony,
  asbestos, barium, beryllium, cadmium.
  chromium, cyanide, fluoride, mercury.
                                          nickel, nitrate, nitrite, selenium, and
                                          thallium under this section shall be
                                          conducted using the sample
preservation, container, and maximum
holding time procedures specified in the
table below:
                                  Contaminant
                                                                                     Preservative '
                                                                                                         Container *   I  Time :


                                                                      	j Cone HNO, to pH <2	j P or G	! 6 months.
Antimony,™..™..—.	••	          I cool 4'C	-	• P or G	j
AsaestOS...		•••	"	;	j cone HNO, to pH <2.	j P or G	 6 months.
Banum,,...,		-	-	   	 Cone HNO, to pH <2	j P or G	, 6 months.
BeryKtum... „	~~	-...-•-	-	-	  	 Cone HNO, to pH <2,.	 P or G	 6 months.
Cadmium...,,,™.......	-	       .. Cone HNO, to pH <2	i P or G	: 6 months.
Ctvorroum.™.™..		•	        | cool. 4'C. NAOH to pH > 12.	! P or G	i 14 days.
Cyanide..™~...		••--	-	-	I None           	-	 P or G	: 1 month.
Ftuonde			-	-	'"!""! Cone "HNO, to pH <2	 P or G	j 28 days
Mercury,,....,	.		'•	       j 00^ HNO, to pH <2	 P or G	 6 months.
  Niuats

    Non-cWonnated,	~	~
  Nilrrte,	—			-
  Stfoowm „„.........,„......,...,.,
  ThaHtum «,.,..._,«—-.«...—	„.....
                                                                            Cool. 4'C
                                                                            Cone H,SO, to pH <2
                                                                            Cooc HNOj 10 pH <2 ----------
                                                                            Cone HNO, to pH <2 ..........
                                                                                                         P or G ................. i 28 days.
                  P or G	
                  PorG	
                  P or G	
                  P or G	
                                                                                                                    I
                                 14 days.
                                 48 hours.
                                 6 months.
                                 6 months.
                                          restrictions, samp* may be .nuially preserved by icing and. knmediatety .Noping it to the laboratory. Upon recent
                                          cone HNO, to pH < 2 and held lor 16 hours before analysis.
      « Se« m«tnod{s) for the mlormatxxi (or preservatxjrt
     (6) Analysis under this section shall
   only be conducted by laboratories that
   have been certified by EPA or the State.
   Laboratories may conduct sample
   analysis under provisional certification
   until January 1.1996. To receive
   certification to conduct analyses for
   antimony, asbestos, barium, beryllium.
   cadmium, chromium, cyanide, fluoride.
   mercury, nickel, nitrate, nitrite and
   selenium and thallium, the laboratory
   must:''
                                             (i) Analyze Performance Evaluation
                                           samples which include those substances
                                           provided by EPA Environmental
                                           Monitoring Systems Laboratory or
                                           equivalent samples prpvided by the
                                           State.
                                            ' (ii) Achieve quantitative results on the
                                          " analyses that are within the.following
                                           acceptance limits:
                                                                                            Contaminant
Antimony —..—.•
Asbesto*	
Barium	
BeryMum'.—
Cadmium	
Ctrormum—
Cyanide	

Mercury —
Nickel..-.
Nitrate—
Nitrite —
                                                                                                               Acceptance limit
                     6*30 at > 0.006 mg/1
                     2 standard deviations
                       based on study
                       statistics.
                      ±15% at  >0.15mg/1
                      ±15% at  iO.OOl  mg/1
                      ±20% at  ^0.002 mg/1
                      ±15% at  >0.01 mg/1
                      ±25% at  >0.1 mg/1
                      ±10% at  21 to 10 mg/l
                      ±30% at  > 0.0005 mg/1
                      ±15% at >0.01 mg/1
                      ±10% at >0.4 mg/1
                      ±15% at >0.4mg/1

-------
              Federal Register / Vol. 57. No.  138 / Friday. July 17. 1992 / Rules  and Regulations       31&1
     Contaminant
                       Acceptance limit
 Selenium.
 Thallium...
±20«i at >0.01 mg/1
= 30S at > 0.002 mg/1
   6. Section 141.24 is amended by
 revising paragraph (f) introductory text. •
 paragraphs (0 introductory text,
 paragraphs (0(4). (f)(S). (0(7). and (0(10).
 (0(11). introductory text, (0(12), the
 introductory texts of (f) (14), (0(15) and
 (0(16) revising (0 (17) and (18), (h)(10).
 (h)(19)(i)(B), and adding paragraphs
.(h)(12)(ixHxiv) to read as follows:

 § 141.24  Organic chemicals other than
 total trialomethanes, sampling and
 analytical requirements.  -
 •    •     •    *    *
   (0 Beginning with the initial
 compliance period, analysis of the
 contaminants listed in § 141.61(a) (1)
 through (21) for the purpose of
 determining compliance with  the
 maximum contaminant level shall be
 conducted as follows:
 •    *     *    •    *
   (4) Each community and non-transient
 non-community water system shall take
 four consecutive quarterly samples for
 each contaminant listed in § 141.61(a)
 (2) through 21 during each compliance
 period, beginning in the initial
 compliance period.
   (5) If the initial monitoring for
 contaminants listed in § 141.61(a) (1)
 through (8) and the monitoring for the
 contaminants listed in § 141.61(a) (9)
 through (21) as allowed in paragraph
.(0(18) has been completed by December
 31, 1992, and the system did not detect
 any contaminant listed in  § 141.61(a) (1)
 through (21), then each ground and
 surface water system shall take one
 sample annually beginning with the
 initial compliance  period.
 •    *     •    •    *
   (7)  Each community and non-transient
 ground water system which does riot
 detect a contaminant listed in
 § 141.61(a) (1) through (21) may apply to
 the State for a waiver from the
 requirements of paragraphs (0(5) and
 (0(6) of this section after completing the
 initial monitoring.  (For purposes. of this
 section, detection is defined as >0.0905
 mg/1.) A waiver shall be effective for no
 more than six years (two compliance
 periods). States may also issue waivers
"to small systems for the initial round of
 monitoring for 1.2,4-trichlorobenzene.
 •    •     •    •    *
   (10) Each community and non-
 transient surface water system which
 does  not detect a contaminant listed in
 § 141.61(a) (1) through (21) may apply to
the State for a waiver from the
requirements of (0(5) of this section
after completing the initial monitoring.
Composite samples from a maximum of
five sampling points are allowed.
provided that the detection limit of the
method used for analysis is less than
one-fifth of. the MCL. Systems meeting.
this criterion must be determined by the
State to be non-vulnerable based on  a
vulnerability assessment during each
compliance period. Each system
receiving a waiver shall sample at the
frequency specified by the State (if any).
  (11) If a contaminant listed in
§ 141.61(a) (2) through (21) is detected at
a level exceeding 0.0005 mg/1 in any
sample, then:
•    «    •    a    4     •        *
  (12) Systems which violate the
requirements of § 141.(>l(a) (1) through
(21), as determined by paragraph (0(15)
of this section, must monitor quarterly.
After a minimum of four consecutive
quarterly samples which show the
system is in compliance as specified  in
paragraph (0(15) of this section the
system and the State determines that
the system is reliably and consistently
below the maximum contaminant level,
the system may monitor at the
frequency and times specified in
paragraph (0(H)(iii) of this section.
*    •    i *    *    «
  (14) The State may reduce the total
number of samples a system must
analyze by allowing the use of
compositing. Composite samples from a
maximum of five sampling points are
allowed, provided that the detection
limit of the method used for analysis  is
less than one-fifth of the MCL.
Compositing of samples must be done in
the laboratory and analyzed within 14
days of sample collection.
•    *     •    *    *
  (15) Compliance with § 141.61(a) (1)
through (21) shall be determined based
on the analytical results obtained at
each sampling point.
•    •     •    «    •
  (16) Analysis for the contaminants
listed in § 141.61{a) (1) through (21) shall
be conducted using .the: following EPA
methods or their equivalent as approved
by EPA. These methods are contained in
Methods for the Determination of
Organic Compounds in Drinking Water,
EPA/600/4-S8/039. ami are available
from the National Technical Information
Service (NTIS) NTlS PB91-231460 and
PB91-146027. U.S. Department of
Commerce, 5285 Port Royal Road.
Springfield. Virginia 22161. The toll-free
number is 800-333-4700.
*    *     •    «    •
  (17) Analysis under this section shall
only be conducted by laboratories that
are certified by EPA or the State
according to the following conditions
(laboratories may conduct sample
analysis under provisional certification
until January 1.1996):
  (i) To receive certification to conduct
analyses for the contaminants in
§ 14I.81(a) (2)  through (21) the
laboratory must
  (A) Analyze Performance Evaluation
samples which include these substances
provided by EPA Environmental
Monitoring Systems Laboratory or
equivalent samples provided by the
State.
  (B) Achieve  the quantitative
acceptance limits under paragraphs
(0(17)(i) (C) and (D) of this section for at
least 80 percent of the regulated organic
chemicals listed in 8 141.61 (a) (2)
through (21).
  (C) Achieve  quantitative results on
the analyses performed, under paragraph
(0(17)(i)(A) of this section that are
within ±20% of the actual amount of the
substances in the Performance
Evaluation sample when the actual
amount is greater than or equal to 0.010
mg/1.
  (D) Achieve  quantitative results on
the analyses performed under paragraph
(0(17)(i)(A) of this section that are
within ±40 percent of the actual amount
of the substances in the Performance
Evaluation sample when the actual
amount is less  than 0.010 mg/1.
  (E) Achieve a method detection limit
of 0.0005 mg/1, according to  the
procedures in Appendix B of Part 138.
  (ii) To receive certification for vinyl
chloride, the laboratory must
  (A) Analyze  Performance Evaluation
samples provided by EPA
Environmental Monitoring Systems
Laboratory or equivalent samples
provided by the State.
  (B) Achieve quantitative results on the
analyses performed  under paragraph
(0(17)(ii)(A) of this section that are
within- ±40 percent of the actual amount
of vinyl chloride in the Performance
Evaluation sample.
  (C) Achieve a method detection limit
of 0.0005 mg/1,  according to  the
procedures in appendix B of part 136.
  (D) Obtain certification for the
contaminants listed  in $ 141.61(a)(2)
through (21).
  (18) States may allow the  use of
monitoring data collected after January
1,1988, required, under section 1445 of
the Act for purposes of initial monitoring
compliance. If the data are generally  .
consistent with the other requirement*
of this  section, the State may use these .
data (i.e., a single sample rather than :
four quarterly samples) to satisfy  the
initial monitoring requirement of

-------
31842       Federal Register / Vol. 57. No. 138 / Friday.  July 17. 1992  /  Rules  and  Regulation
 paragraph {f)(4) of this section. Systems
 which use grandfathered samples and
 did not detect any contaminant listed
 § 141.61(a)(2) through (21) shall begin.
 monitoring annually in accordance with
 paragraph (0(5) of this section beginning
 with the initial compliance period.
 «    •    •    •    •
   (h)  * *  *
   (10) The State may reduce the total
 number of samples a system must
 analyze by allowing the use of
 compositing. Composite samples from a
 maximum of five sampling points are
 allowed, provided that the detection
= limit of the method used for analysis is
 less than one-fifth of the MCL
 Compositing of samples must be done in
 the laboratory and analyzed within 14
 days of sample collection.
 •    *    •    •    «
   (12)  * * *
   (ii) Method SOS. "Analysts of
 Organohalide Pesticides and
 Commercial Polychlorinated Biphenyl
 Products (Aroclors) in Water by
 Microcxtraction and  Gas
 Chromatography." Method 505 can be
 used to measure alachlor, atrazine.
 chlordane, endrin, heptachlor.
 heptachlor epoxide, hexachlorobenzene,
 hexachlorocyclopentadiene, lindane.
 methoxychlor. toxaphene and simazine.
 Method 505 can be used as  a  screen for
 PCBs.
   (Hi) Method 507. "Determination of
 Nitrogen- and Phosphorus-Containing
 Pesticides in Ground Water by Gas
 Chromatography with a Nitrogen-
 Phosphorus Detector." Method 507 can
 be used to measure alachlor.  atrazine
 and simazine.
   (iv) Method 508. "Determination of
 Chlorinated Pesticides in Water by Gas
 Chromatography with an Electron
 Capture Detector." Method 508 can be
 used to measure chlordane. endrin,
 heptachlor. heptachlor epoxide,
 hexachlorobenzene,.lindane,
 methoxychlor and toxaphene. Method
 508 can be used as a screen for PCBs.
 ******
    (vi) Method 515.1.  "Determination of
 Chlorinated Acids in Water by Gas
 Chromatography with an Electron
 Capture Detector." Method-515.1 can be
 used to measure 2,4-D, dalapon. dinoseb,
 pentnchlorophenol, picloram and 2,4,5-
 TP (Silvex).
    (vii) Method 525.1, "Determination of
 Organic Compounds in Drinking Water
 by Liquid-Solid Extraction  and Capillary
 Column Gas Chromatography/Mass
 Spectrometry." Method 525.1 can be
 used to measure alachlor, atrazine,
 chlordane, di(2-ethylhexyl)adipate. di(2-
 ethylhexyljphthalate, endrin. heptachlor,
 heptachlor epoxide,  hexachlorobenzene.
hexachlorocyclopentadiene. lindane,
methoxychlor, pentachlorphenol.
polynuclear aromatic hydrocarbons,'
simazine. and toxaphene.
  (viii) Method 531.1. "Measurement of
N-Methyl Carbamoyloximes and N-
Methyl Carbamates in Water by Direct
Aqueous Injection HPLC with Post-
Column Deriv'atization." Method 531.1
can be used to measure aldicarb,
aldicarb sulfoxide, aldicarb sulfone,
carbofuran and oxamyl.
  (ix) Method 1613. 'Tetra- through
Octa- Chlorinated Dioxins and Furans
by Isotope Dilution." Method 1613 can
be used to measure 2.3,7,8-TCDD
(dioxin). This method is available from
USEPA-OST, Sample Control Center.
P.O. Box 1407. Alexandria, VA 22313.
  (x) Method 547. "Analysis of
Glyphosate in Drinking Water by Direct
Aqueous Injection HPLC with Post-
Column Derivatization" Method 547 can
be used to measure glyphosate.
  (xi) Method 548, "Determination of
Endothall in Aqueous Samples." Method
548 can be used to measure endothall.
  (xii) Method 549, "Determination of
Diquat and Paraquat in Drinking Water
by High Performance Liquid
Chromatography with Ultraviolet
Detection." Method 549 can be used to
measure diquat.
  (xiii) Method 550, "Determination of
Polycyclic Aromatic Hydrocarbons in
Drinking Water by Liquid-Liquid
Extraction and HPLC with Coupled
Ultraviolet and Fluorescence Detection".
Method 550 can be  used to measure
benzo(a)pyrene and other polynuclear
aromatic hydrocarbons.
  (xiv) Method 550.1. "Determination of
Polycyclic Aromatic Hydrocarbons in
Drinking Water by Liquid-Solid
Extraction and HPLC with Coupled
Ultraviolet and Fluorescence Detection".
Method 550.1 can be used to measure
benzo(a)pyrene and other polynuclear
aromatic hydrocarbons.
*    •    «     •    *
  (18) Detection as used in this
paragraph shall be  defined as greater
than or equal to the following -
concentrations for each contaminant.
Contaminant
Alachlor — _._.._ ....«._
Aidicarta 	 :__.._../„.„__...
Aldicarb sutfoxxJ* ._ 	 .......
Aldicarb suttone 	
BenzoCalpyreoff _ 	 	 ,. .,. , M -
ChlordarM 	 	 	 	 	 	 	
Dicrornochloropropane (DBCP) 	
Di (2-ethythexyt) adipaia 	 	
Di (2-etftyftwxyt) pnthaltM 	
Detection
limit (mo/0
.0002
.0005
.0005
.0006
.0001
.00002
.0009
.0002
.001
.00002
.0009
.0008
         Contaminant
          Detection
         limit (mg/1)
Dinoseb	
Diquat	
2.4-0	
Endothall	
Endrin	_	_	
Ethyton* abrorrwte (EQB)	
Glyphosate	
Heptachlor	
Heplachkx epoxide	
Hexachlorobenzene	
Hexachlorocyclopentadiene	
Undane	
Methoxychlor	
Oxamyl	
Picloram	
Polychlonnated biphenyls (PCBs) (as
  decachlorobiphenyl)	
Pentachtorophenol	
Simazine	„	
Toxaphene	
2.3.7.8-TCDD (Dioxin)	
2.4,5-TP (Silvox)	..,
      -1
.0002
.0004
.0001
.009
.00001
.00001
.006
.00004
.00002
.0001
.0001
.00002
.0001
.002
.0001

.0001
.00004
.00007
.001
.000000005
.0002
  (19) * * *
  (!)••*
  (B) Achieve quantitative results on the
analyses that are within the following
acceptance limits:
     Contaminant
OBCP	_	_		
EDB	
Alachlor	_	
Atrazine	-	
Benzotalpyrene	—
Carbofiran—		
Chtordao*		
Dalapon	:.—,	,
Di(2-ethyt)exyr)adip«te ....
DK2-ethythexyf)prithalat»
Dinoseb.-	-	-	
Dkjuat.,.-			
EndothaH.._		
Endnn	_.	
Glyphosate	_	
Heptachlor._	,
Heptachlor epoxide	,
Hexachlorobenzene	
Hexachloro-
  cydopentadiena
U'ndan*	
Methoxychlof		
Oxamyl	«.
PCSs'as
  Decachlorobiphenyl)
Piclonvn		
Simazin*	—	_,
Toxapherve............	
Aldicarb....	...
Aldicarb sulfmbde	
Aldicarb suttone	_	
Pentachlorophenol	..
2.3,7,8-TCOO (Dioxin)...
2.4-O	........	._.
2.4.5-TP (SivM)	
   Acceptance limits
      (percent)
±40
±40.
2 standard deviations.
±45.
±45.
2 standard deviations.
2 standard deviations
2 standard deviations.
2 standard deviations.
2 standard deviations.
2 standard deviaDons.

2 standard deviations.
±45.
±45.
2 standard deviations.
2 standard deviations.
±45.
2 standard deviations.
0-200.

2 standard deviations.
2 standard deviations.
±45.
2 standard deviations.
2 standard deviations.
2 standard deviations.
±50,
2 standard deviations.
±50.
±50.
                                           7. Section 141.32 is amended by
                                         adding paragraphs (e)(53) through (75) to
                                         read as follows:

-------
             Federal Register / Vol. 57. No. 138 / Friday. July 17. 1992 / Rules  and Regulations       31843
§141.32 Pm*c notmejUoo.
  (53) Antimony. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that antimony is a health
concern at certain levels of exposure.- • •• -
This inorganic chemical occurs naturally
in soils, ground water and surface
waters and is often used in the flame
retardant industry. It is also used in
ceramics, glass, batteries, fireworks and
explosives. It may get into drinking
water through natural weathering of
rock, industrial production, municipal
waste disposal or manufacturing
processes. This chemical has been
shown to decrease longevity, and
altered blood levels of cholesterol and
gfucose in laboratory animals such as •
rats exposed to high levels during their
lifetimes. EPA has set the drinking water
standard for antimony at 0.006 parts per
million (ppm) to protect against the risk
of these adverse health effects. Drinking
water which meets the EPA standard is
associated with little to none of this risk
and should be considered safe with
respect to antimony.
  (54) Beryllium. The United Slates
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that beryllium is a health
concern at certain levels of exposure.
This inorganic metal occurs naturally in
soils, ground water and surface waters
and is often used in electrical equipment
and electrical components. It generally
gets into water from runoff from mining
operations, discharge from processing
pfants and improper waste disposal.
Beryllium compounds have been
associated with damage to the bones
end lungs and induction of cancer in
Saboratory animals such as rats and
mice when the animals are exposed at
feigh levels over their lifetimes. There is
Simited evidence to suggest that
beryllium may pose a cancer risk via
drinking water exposure. Therefore.
EPA based the health assessment on
noncancer effects with an extra
uncertainty factor to account for
possible carcinogenicity. Chemicals that
cause cancer in laboratory animals also
nay increase the risk of cancer in
humans who are exposed over long
.periods of time. EPA has set the drinking
water standard for beryllium at 0.004
part per million (ppm) to protect againrt
&e risk of these adverse health effects.
Drinking water which meeti the EPA
standard is associated with little to none
of this risk and should be considered
sife with respect to beryllium.
  (55) Cycnfdc. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that cyanide is a health
concern at certain levels of exposure.
This inorganic chemical is used in
electroplating, steel processing, plastics.
synthetic fabrics and fertilizer products.
It usually gets into water as a result of
improper waste disposal. This chemical''
has been shown to damage the spleen.
brain and Kver of hunwins fatally
poisoned with  cyanide. EPA has set the
drinking water standard for cyanide at
0.2 parts per million (ppm) to protect
against the risk of these adverse health
effects. Drinking water which meets the
EPA standard is associated with Httle to
none of this risk and should be
considered safe with  respect to cyanide.
  (56) Nickel. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that nickel poses a health
concern at certain levels of exposure.
This inorganic metal occurs naturally in
soils, ground water and surface waters
and is often used in electroplating,
stainless steel and alloy products, it
generally gets into water from mining
and refining operations. This chemical
has been shown to  damage the heart
and liver in laboratory animals when
the  animals are exposed to high levels
over their lifetimes. EPA has set the
drinking water standard at 0.1 parts per
million (ppm) for nickel to protect
against the risk of the*: adverse effects.
Drinking water which meets the EPA
standard is associated with little to none
of this risk and should be considered
safe with respect to nickel.
  (57) Thallium. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that thallium is a health
concern at certain high levels of
exposure. This inorganic metal is found
naturally in soils and LSI used in
electronics. Pharmaceuticals, and the
manufacture of glass  and alloy*. This
chemical has been* shown to damage the
kidney, liver, brain and. intestines of
laboratory animals wtu:n the animals
are  exposed at high levels over their
lifetimes. EPA has set the drinking water
standard for thallium at OJJQ2 parts per
million (ppm) to protect against the risk
of these adverse health effects. Drinking
water which meets the EPA standard is
associated with little  to none of this risk
and should be considered safe with
respect to thallium.
  (58) Benzofajpyreije. The United
States Environmental Protection Agency
(EPA) sets drinking, water standards and
has determined that benzo[alpyrene is a
health concern at certain lev*ls of
exposure. Cigarette s«mt.B sn4  .
charbroiled meats are commorv source of
genera! exposure. The major source of
benzo[a)pyrene in drinking water is the
leaching from coal tar lining and
sealants in water storage tanks. This
chemical has been shown to cause
cancer in animals such as rats and mice
when the animals are exposed at high
levels. EPA has set the drinking water   .
standard for benzo[aJpyrene at 0.0002
parts per million (ppm) to protect
against the risk of cancer. Drinking
water which meets the EPA standard is
associated with little to none of this risk
and should be considered safe with
respect to benzo[ajpyrene.
  (59) Dalapon. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that dalapon is a health
concern at certain levels of exposure.
This organic chemical is a widely used
herbicide. It may get into drinking water
after application to control grasses in
crops, drainage ditches and along
railroads. This chemical has been shown
to cause damage to the kidney and liver
in laboratory animals when the animals
are exposed to high levels over their
lifetimes. EPA has set the drinking water
standard for dalapon at 0.2 parts per
million (ppm) to protect against the risk
of these adverse health effects. Drinking
water which meets the EPA standard is
associated with little to none of this risk
and should be considered safe with
respect to dalapon.
  (60) Dichloromethane. The United
States Environmental Protection Agency
(EPA) sets drinking water standards and
has determined that dichloromethane
(methylene chloride] is a health concern
at certain levels of exposure. This
organic chemical is a widely used
solvent It is used in the manufacture of
paint remover, as a metal degreaser and
as an aerosol propellant. It generally
gets into drinking water after improper
discharge of waste disposal. This
chemical has been shown to cause
cancer hi laboratory animals such as
rats and mice when the animals are
exposed at high levels over their
lifetimes. Chemicals that cause cancer in
laboratory animals alto may increase
the risk of cancer In humans who are
exposed over long periods of time. EPA
has set the drinking water standard for
dichloromethane at 0.005 parti per
million (ppm) to reduce the risk of
cancer or other adverse health effects
which have been observed in laboratory
anfmats. Drinking water which meets
this standard is associated with tittle to
none of this risk and should be
considered safe with respect to
dichloromethane.
  (&l)Di(Z-ethy!/iexyfJadipate. The
United States Environmental Protection
Agency (EPA) sets drinking water

-------
 31844        Federal RegJater  / VoL 57. No. 138 / Friday. July 17. 1992 / Rulea and Regulations
 standards and has determined that di(2-
 ethylhexyl)adipate is a health concern
 at certain levels of exposure. Di(2-
 elhylhexyl)adipate is a widely used
 plasticizer in a variety of products.
 including synthetic rubber, food
 packaging materials and cosmetics. It
 may get into drinking water after
 improper waste disposal. This chemical.
 has been shown to damage liver and
 testes in laboratory animals such as rats
 and mice exposed to high levels. EPA
 has set the drinking water standard for
 di(2-ethylhexyl)adipate at 0.4 parts per
 million (ppm) to protect against the risk
 of adverse health effects. Drinking water
 which meets the EPA standards is
 associated with little to none of this risk
 and should be considered safe with
 respect to di(2-ethylhexyl)adipate.
   (62) Di(2-ethylhexyl)phthalate. The
 United States Environmental Protection
 Agency (EPA) sets drinking water
 standards and has determined that di(2-
 ethylhexyljphthalate is a health concern
 at certain levels of exposure. Di(2-
 ethylhexyljphthalate is a widely used
 plasticizer. which is primarily used in
 the production of polyvinyl chloride
 (PVC) resins. It may get into drinking
 water after improper waste disposal.
 This chemical has been shown to cause
 cancer in laboratory animals such as
 rats and mice exposed to high levels
 over their lifetimes. EPA has set the
 drinking water standard for di(2-
 elhylhexyljphthalate at 0.004 parts per
 million (ppm) to reduce the risk of
 cancer or other adverse health effects
 which have been observed in laboratory
 animals. Drinking water which meets
 the EPA standard is associated with
 little to none of this  risk and should be
 considered safe with respect to di(2-
 ethylhexyl)phthalate.
   (63) Dinoseb. The United States
 Environmental Protection Agency (EPA)
 sets drinking water standards and has
 determined that dinoseb is a health
 concern at certain levels of exposure.
 Dinoseb is a widely used pesticide and
 generally gets into drinking water after
 application on orchards, vineyards and
 other crops. This chemical has been
 shown to damage the thyroid and
 reproductive organs in laboratory
 animals such as rats exposed to high
 levels. EPA has set the drinking water
 standard for dinoseb at 0.007 parts per
 million (ppm) to protect against the risk
 of adverse health effects. Drinking water
 which meets the EPA standard is
 associated with little to none of this risk
and should be considered safe with
respect to dinoseb.
  (64) DlquaL The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
  determined that diquat is a health
  concern at certain levels of exposure.
  This organic chemical is a herbicide
  used to control terrestrial and aquatic
  weeds. It may get into drinking water by
  runoff into surface water. This chemical
  has been shown to damage the liver.
  kidney and gastrointestinal tract and
.' causes cataract-formation in-laboratory
  animals such as dogs and rats exposed
  at high levels over their lifetimes. EPA
  has set the drinking water standard for
  diquat at 0.02 parts per million (ppm)  to
  protect against the risk of these adverse
  health effects. Drinking water which
  meets the EPA standard is associated
  with little to none of this risk and should
  be considered safe -with respect to
  diquat.
   (65) Endothall. The United States
  Environmental Protection Agency (EPA)
  has determined that endothall is a
  health concern at certain levels of
  exposure. This organic chemical is a
  herbicide used to  control terrestrial and
  aquatic weeds. It may get into water by
  runoff into surface water. This chemical
  has been shown to damage the liver,
  kidney, gastrointestinal tract and
  reproductive system of laboratory
  animals such as rats and mice exposed
  at high levels over their lifetimes. EPA
  has set the drinking water standard for
  endothall at 0.1 parts per million (ppm)
  to protect against  the risk of these
 adverse health effects. Drinking water
 which meets the EPA standard is
 associated with little to none of this risk
 and should be considered safe with
 respect to endothall.
   (66) Endrin. The United States
 Environmental Protection Agency (EPA)
 sets drinking water standards and has
 determined that endrin is a health
 concern at certain levels of exposure.
 This organic chemical is a pesticide no
 longer registered for use in the United
 States. However, this chemical is
 persistent in treated soils and
 accumulates in sediments and aquatic
 and terrestrial biota. This chemical has
 been shown to cause damage to the
 liver, kidney and heart in laboratory
 animals such as rats and mice when the
 animals are exposed at high levels over
 their lifetimes. EPA has set the drinking
 water standard for endrin at 0.002 parts
 per million (ppm) to protect against the
 risk of these adverse health effects
 which have been observed in laboratory
 animals. Drinking water that meets the
 EPA standard is associated with little to
 none of-this risk and should be
 considered safe with respect to endrin.
   (67) Glyphoaate. The United State*
 Environmental Protection Agency (EPA)
 sets drinking water standards and has
 determined that glyphosate is i health
  concern at certain levels of exposure.
  This organic chemical is a herbicide
  used to control grasses and weeds. It
  may get into drinking water by runoff
  into surface water. This chemical has
  been shown to cause damage to the liver
  and kidneys in laboratory animals such
  as rats and mice when .the animals are- '••:•
 • exposed at high levels over their
  lifetimes. EPA has set the drinking water
  standard for glyphosate at 0.7 parts per
  million (ppm) to protect against the risk
  of these adverse health effects. Drinking
  water which meets the EPA standard is
  associated with little to none of this risk
  and should be considered safe with
  respect to glyphosate.
    (88) HexaChlorobenzene. The United
  States Environmental Protection Agency
  (EPA) sets drinking water standards and
  has determined that hexachlorobenzene
  is a health concern at certain levels of
  exposure. This organic chemical is
  produced as an impurity in the
  manufacture of certain solvents and
  pesticides. This chemical has been
  shown to cause cancer in laboratory  •
  animals such  as rats and mice when the
 animals are exposed to high levels
 during their lifetimes. Chemicals that
 cause cancer in laboratory animals also
 may increase the risk of cancer in
 humans who are exposed over long
 periods of time. EPA has set the drinking
 water standard for hexachlorobenzene
 at 0.001 parts per million (ppm) to
 protect against the risk of cancer and
 other adverse health effects. Drinking
 water which meets the EPA standard is
 associated with little to none of this risk
 and should be considered safe with
 respect to hexachlorobenzene.
   (69) Hexachlorocyclopentadiene. The
 United States Environmental Protection
 Agency (EPA) establishes drinking
 water standards and has determined
 that hexachlorocyclopentadiene is a
 health concern at certain levels of
 exposure. This organic chemical is used
 as an intermediate in the manufacture of
 pesticides and flame retardants. It may
 get into water  by discharge from
 production facilities. This chemical has
 been shown to damage the kidney and
 the stomach of laboratory animals when
 exposed at high levels over their
 lifetimes. EPA has set the drinking water
 standard for hexachlorocyclopentadiene
 at 0.05 parts per million (ppm) to protect
 against the risk of these adverse health
 effects. Drinking water which meets the
 EPA standard is associated with little to
none of this risk and should be
considered safe with respect to
hexachlorocyclopentadiene.
  (7Q\Oxamyl. The United States
Environmental Protection Agency (EPA)
establishes drinking water standards

-------
                               / Vot. S7; No. 13« / Ffkiay, July 17. 1992  /  Rnles am! Regulations
and has determined that oxamyl is a
health concern at certain levels of
exposure. This organic chemical is used
as a pesticide for the control of insects
and other pests. It may get into drinking
water by runoff into surface water or
leaching into ground water. This
chemical has been shown, to.damage the •.
kidneys of laboratory animals such as
rats when exposed at high levels over
their lifetimes. EPA has set .the drinking
water standard for oxamyl at 0.2 parts
per million (ppm) to protect against the
risk of these adverse health effects.
Drinking water which meets the EPA
•standard is associated with little to none
of this risk and should be considered
safe with respect to oxamyL
   (71) Picloram. The United States
Environmental Protection Agency (EPA)
sets drinking water standards and has
determined that picloram is a health
concern at certain levels of exposure.
This organic chemical is used as a
pesticide for broadleaf weed control. It
may get into drinking water by runoff
into surface watnr or leaching into
ground water as a result of pesticide
application and improper waste
disposal. This chemical has been shown
to cause damage to the kidneys and
liver in laboratory animals such as rats
when the animals are exposed at high
levels over their lifetimes. EPA has set
the drinking water standard for picloram
at 0.5 parts per million (ppm) to protect
against the risk of these adverse health
effects. Drinking water which meets the
EPA standard is associated with little to
none of this risk and should be
considered safe with respect to
picloram.
   (72) Simazine. The United States
Environmental Protection Agency (EPA)
 sets drinking water standards and has.
 determined that simazine is a health
 concern at certain levels of exposure.
This organic chemical is a herbicide   -
 used to control annual grasses and
 broadleaf weeds. It may leach into
 ground water or runs off into surface
 water after application. This chemical
 may cause cancer in laboratory animals
 such as rats and mice exposed at  high
 levels during their lifetimes. Chemicals
 that cause cancer in laboratory animals
 also may increase the risk of cancer in
 humans who  are exposed over long
 periods of time. EPA has set the drinking
.water standard for simazine at 0.004
 parts per million (ppm) to reduce the
 risk of cancer or other adverse health
 effects. Drinking water which meets the
 EPA standard is associated with little to
 none of this risk and should be .
 considered safe with respect to
  simazine.
  (73) 13,4-TrichJombenze/ie. The
United States Environmental Protection
Agency (EPA) seta drinking water
standards and has determined that 1.2.4-
trichlorobenzene is a health concern at
certain levels of exposure. This organic
chemical is used as a dye carrier and as
a precursor in herbicide manufacture. It.
generally gets into drinking water by
discharges from industrial activities.
This chemical has been shown to cause
damage to several organs, including the
adrenal glands. EPA has set the drinking
water standard for 1,2,4-
trichlorobenzene at 0.07' parts per
million (ppm} to protect against the risk
of these adverse health effects. Drinking
water which meets the EPA standard is
associated with little to none of this risk
and should be considered safe with
respect to 1.2.4-trichlorobenzene.
  (74) 1.13-Trichhroethane. The United
States Environmental Protection Agency
(EPA) sets drinking water standards and
has determined 1,1.2-tricbloroethane is a
health concern  at certain levels of
exposure. This  organic chemical is an
intermediate  in the production of 1.1-
dichloroethytene. It generally gets into
water by industrial discharge of wastes.
This chemical has been shown to
damage the kidney and liver of
laboratory animals such as rats exposed
to high levels during their lifetimes. EPA
has set the drinking water standard for
1.1.2-trichloroethane at 0.005 parts per
million (ppm) to protecJ against the risk
of these adverse health effects. Drinking
water which  meets the EPA standard is
associated with little to none of this risk
and should be considered safe with
respect to 1.1.2-trichloroetbane,
   (75) 2.3,7,8-TCDD (DioxJn). The United
States Environmental Protection  Agency
(EPA) sets drinking water standards and
has determined that dioxin is a health
concern at certain levels of exposure.
This organic  chemical is an impurity in
the production of some pesticides. It
may get into  drinking water by
industrial discharge of wastes. This
chemical has been shown to cause
 cancer in laboratory animals such as
 rats and mice when the animals are
 exposed at high levels over their
 lifetimes. Chemicals that cause cancer in
 laboratory animals also may increase
 the risk of cancer in humane who are
 exposed over long periods of time. EPA
 has set the drinking water standard for
 dioxin at 0.00000003 pacts per million
 (ppm) to reduce the risk of cancer or
 other adverse tessltk effects which have
 been observed in laboratory animals.
 Drinking water which meets this
 standard is associated with little to none
 of this risk and should be considered
 safe with respect to dioxin.
  8. Section 141.40 is amended by
revising paragraph (e\, revising
paragraph (f). revising paragraphs (g)
and (h). and revising paragraphs (n) (11)
and (12) including the tables to read as
follows:

§141.40  Special monitoring for organic ..,
  (e) Community water systems and
non-transient, non-community water
systems shall monitor for the following
contaminants except as provided in
paragraph (f) of this section:
(1) Chloroform
f2)- Bromodichloromethane
(3) Chlorodibromomethane
(4) Bromoform
(5) Chlorobenzene
•(6) m-Dichlorobenzene
(8) 1.1-Dichloropropene
(9) 1.1-Dichloroethane
(10)  1.1.2,2-Tetrachloroethane
(11)  1.3-Dichloropropane
(12)  Chloromethane
(13)  Bromomethane
(14)  1.2,3-Trichloropropane
(15)  1.1.1.2-Tetrachloroethane
(16)  Chloroethane
(17J  2.2-Dichloropropane
(18)  o-Chlorotoluene
(19)  p-Chlorotoluene
(20)  Bromobenzene
(21)  i:3-Dichloropropene
  (f) [Reserved]
  (g) Analysts under this section shall
be conducted using the recommended
EPA methods as follows, or their
equivalent as determined by EPA: 502.1.
"Volatile Halogenated Organic
Compounds in Water by Purge and Trap
Gas Chromatography," 503.1. "Volatile
Aromatic and Unsaturated Organic
Compounds in Water by Purge and Trap
Gas Chromatography." 524.1. "Volatile
Organic Compounds in Water by Purge
and Trap Gas Chromatography/Mass
Spectrometry." 524.2, "Volatile Organic
Compounds in Water by Purge and Trap
Capillary Column Gas Chromatography/
Mass Spectrometry, or 502.2. "Volatile
Organic Compounds in Water by Purge
and Trap Gas Chromatography with
Photoionization and Electrolytic
Conductivity Detectors m Series." These
methods are contained in "Methods for
the Determination of Organic
Compounds in Finished Drinking Water
and Raw Source Water." September
1988. available from the Drinking Water
 Public Docket or the National Technical
 Information SenrfcarfNTIS). NTTS PB91-
 231480 and PB91-146027, U:S; *   '
 Department of Commerce, 5285 Port-
 Royal Road. Springfield. Virginia 22161.
 The toll-free number is 800-336-4700.

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  31846
                 Fedaral Regute,  / VoL  57. No. 13* / Friday. July  17.  1992 / Rnles
     (h) Analysis under this section shall
  only be conducted by laboratories
  approved under § 141.24(g)(ll).
    (11) List of Unregulated Organic
  Contaminants:
    Organic contammann   ',  EPA analytic* matnod
                                               (22) Hexachlorobenzene
                                               (23) 2.3.7,8-TCDD (Dioxin)
                                               (b) '  *  *
                                                      Contaminant
                                MO.G (mg
                                    1)
  AJdon „.,..„„.„	,._...
  Bulacnlor „..,.„	
  Camaryt,,...,	„	
  Dicamba				™
  DteWfin			
  3-Hyatoxycart>ofuran...."
  Melhomy) .„.....„.„	„..,
  Meiotachlor,,		J
  Meinbuiin..	
  Pf opachtor	«..™...™.....
                    —: 505. 508. and 525
                    	• 507. 525_
                    ,...1 581.1.
                    ...J 515.1.
                    ....I 505. 508. and 525.
                    ..-! 581.1.
                    ...J 531.1.
                    ....| 507. 525.
                    .-.! 507. 508. and 525.
                    ... J 507. 525.
   (12) List of Unregulated Inorganic
 Contaminants:
    Inorganic coniammams
                            EPA analytical
                               me mod
 <21) Oalapon..:.   	
 (22) Oi(2-etnyth«xyf)adipate.
 (23) Dinowb	
 (24) DiQuat	
 (25) EndotnaM	„
 (26)Endrin	.".".':.'".'.'.".'."."
 (27) Glyphosata	"""!	•
 (28) HexacWorccyctopentadwoi'.'!
 (29) Oxamyi (Vydata)	
 (30) Pickxam	
 (31) Simazme	Z.....1.."
 (32) 1.2.<-Trichtofoben2en«""
 (33) 1.1,2-Tnchtofoetnan*	
0.2
 .4
 .00
 .02
 .1
 .002
 .7
 .05
 .2
 .5
 .004
 .07'
 .003
                .,_.........	 Cotonmetnc,
   9. Section 141.50 is amended by
 adding paragraphs (a)(19) through
 (a (23) and paragraphs (b)(21) through
 (b](33) in the table in paragraphs (b) as
 follows:

 § 141.50   Maximum contaminant l«v«l
 goals for organic chamtealt.
  (a) ' •  •
  (19) Benzofajpyrene
  (20) Dichloromethane (methylene
chloride)
  (21) Di(2-ethylhexyl)phthalate
   10. Section 141.51 is amended by
adding entries (b)(ll) through (b)(l5) as
follows:

5 141.51  Maximum contaminant tevtJ
8oal« for Inorganic contaminant*
  (b) * « •
                                                    Contaminant
                               MCLG (mg/
                                   1)
                                           (11) Antimony	
                                           (12) Beryllium	
                                           (13) Cyanide (as tree Cyanide).:
                                           (14) Nickel	
                                           (15) Thallium	
                                   0.006
                                    .004
                                    .2
                                    .1
                                    .0005
       9141.60  Effective data*.
         (a)' ' '
         (3) The effective date for paragraphs
       (a)(19) through (a)(21) and (c)(19)
       through (c)(33) of § 141.61 is January 17.
   (b) * • •
   (3) The ef/ective.date for paragraphs-
 b)(ll) through (b)(15) of 8 141.62 is
January 17. 1994.
   12. Section 141.61 is amended by
adding paragraphs (a)(19)-{21); by
revising paragraph (b) including the
table: by revising the introductory text
to paragraph (c): and  by adding
paragraphs (c)(19}-{33).
                                                                                      5 141.81   Maximum contaminant
                                                                                      organic contaminant*.
                                                                                                                           for
                                                                                          CAS No.
                                                                                                       Contaminant    MCL (mg/l)
                                                                                       19) 75-09-2
                                                                                       20) 120-82-1

                                                                                       21) 79-00-5
                    Dichtorometnane....
                    1.2.4-TncNoro-
                      benzene.
                    1.1.2-Tncnkxo-
                      etnane.
                                   0005
                                    .07

                                    .005
                                             11. Section 141.60 is amended by
                                          adding paragraphs (a)(3) and fb)(3) to
                                          read as follows:
       (b)The Administrator, pursuant to
      ection 1412 of the Act. hereby identifies
      s indicated in the Table below granular
      ctivated carbon (GAG), packed tower
      eration (PTA), or oxidation (OX) as the
      est technology treatment technique, or
      ther means available for achieving
     compliance with the maximum
     contaminant level for synthetic organic
     contaminants identified in paragraphs
     (a) and (c) of this section:
                            BATFOR ORGANIC CONTAMINANTS LISTED IN SECTION 141.61 (A) AND
                                                                                               (c)
   50-32-8
   75-99-0
   75-09-2
  103-23-1
  117-81-7
   88-85-7
   85-00-7
  145-73-3
   72-20-45
 1071-53-6
  1 18-74-1
            Dalapon
            Dchtofometnane ........
            Di (2-«thyff>exyl) adipate
            Oi (2-«thylneryl) phthalals
            Dino»et)...._
            Douat.....           "
            Enoothall
            Enonn
            Glypoosata
            Hexacfttofooennna ...
»,
23135-22-0
 1918-02-1
  122-34-8
  120-82-1
   79-00-5
 1746-01-«
           CTwmyl (Vydala)
           Pxaofam
           SJmanna
           1.1.2-TncNofoethan*
           2.3.7.8-TCDD (Diorin)
GAC






PTA
X
X
	
X
X
X
ox


X





-------
             Federal Register / Vol. 57. No. 138 / Friday,  fuly  17, 1992 / Rules and Regulations       31847
                                              CAS No.
                                                                          Contaminant
                                                                                                        MCL|mg/l)
09)





(25) '
ipfit





(321


. . 50-32-*
75-99-0
103-23-1
117-81-7
	 88-85-7
85-00-7.
145-73-3
• 	 • 72-20-8
	 1071-53-6
	 118-74-1
	 77-47-4
	 23135-22-0
	 1918-02-1
	 122-34-9
	 1746-01-6

BanzofaJpyrene 	 	 	
Dalapcifi T- -
Di(2-ethylrie)ryl) adipate 	 .'. 	 	
f>(2-ethylhexyl) pntnalate 	 	 	
Dinoseto 	 . 	 	 '. 	 - 	

EndotfwM
Endnn 	 	
Gtyphosate 	 	
Hexacl*io(orbef>zef>o 	
HexacWorocyctopentadiene 	
Oxamyl (Vydate) . . 	


2 3,7.8-TCOD (Dtoxm) 	 .-. 	 ; 	

0.0002
0.2
0.4
0.006
0007
002..,
0.1
0.002
O.V
0001
0.05
0.2
0.5
0004
3- 10 •

  3. Section 141.62 is amended by
revising the introductory text to
paragraph (b): by adding paragraphs
(b){ll) through (b){15); and by revising
paragraph (c), including the table, to
read as follows:
§ 141.62 Maximum contaminant levels for
Inorganic contaminants.
•    *    *    •    *

  (b) The maximum contaminant levels
for inorganic contaminants specified in
paragraphs (b)(2J—(6). (b)(10). and
(b)(ll}—{15) of this section apply to
community water systems and non-
transient, non-community water
systems. The maximum contaminant
level specified in paragraph (b)(l) of this
section only applies to community water
systems. The maximum contaminant
levels specified in (b)(7). (b)(8). and
(b)(9) of this section apply to community
water systems; non-transient, non-
community water systems: and transient
non-community water systems.
                                                Contaminant
                                                                    MCL (mg/l)
* • • e e





b.oos
„ 	 -0.004
.. .. -0.2
	 0.1
	 	 	 	 0.002

  (c) The Administrator, pursuant to
Section 1412 of the Act, hereby
identifies the following as the best
technology, treatment technique, or
other means available for achieving
compliance with the maximum
contaminant levels for inorganic
contaminants identified in paragraph (b)
of this  section, except fluoride:

 BAT FOR INORGANIC COMPOUNDS LISTED
         IN SECTION 141.62(8}
Chemical Name

A3t>63tO3 	 '...,.,, ,.,,r,.....,
Bsnuni i
Beryfhum 	


C^arwde 	 	 	

ttcfcaj 	
Nrfratv 	 	 	 	 	 	 	 „
N&ftTte 	 	 	 ; 	
Sfttonium 	


BAT(S)
2.7
2.3.8
5.6.7.9
1.2.5.6.7
2.5,6.7
' 2.5.6 »,7
5.7,10
2 ' *6 ' 7 '
5.6.7
5.7.9
5.7
1.2 '.6.7.9
1,5

  1 BAT only rf influent Hg concentrations <10jig/1.
  1 BAT lor Chromium III ooty.
  1 BAT (or Seicmum IV orty.
Key to BATS in Table
1 = Activated Alumina
2 = Coagulation/Filtration
3 = Direct and Diatomite Filtration
4 = Granular Activated Carbon
5 = Ion Exchange
6=Lime Softening
7 = Reverse Osmosis
8=Corrosion Control
9 = Electrodialysis
10=Chlorine
ll = Ultraviolent
   14. Section 141.89(a) table is amended
by revising footnote 9 to read as follows:

§141.99  Analytical methods.
•    *    •    •    •

   • For analyzing lead and copper, the
technique applicable to total metals
must be used and samples cannot be
filtered. Samples that contain less than 1
NTU (nephelometric turbidity unit) and
are properly preserved (cone HNO» to
pH <2) may-i>e analyzed directly
(without digestion) for total metala:
otherwise, digestion ia required.
Turbidity must be measured on the
preserved samples just prior to when
metal analysis  is initiated. When
digestion is required, the 'total
recoverable' technique as defined in the
method must be used.
PART 142—NATIONAL PRIMARY
DRINKING WATER REGULATIONS
IMPLEMENTATION

  1. The authority citation for part 142
continues to read as follows:
  Authority: 42 U.S.C. 300g. 300g-l. 300g-2,
300g-3.300g-4. 300g-5.300g-fl, 300H and
300J-9.
  2. Section 142.16 is amended by
revising the introductory text to
paragraph (e), and revising paragraph
(e)(2) to read as follows:
} 142.16  Special Primary Requirements.
•     •    *    *  .  «
  (e)  An application for approval of a
State program revision which adopts the
requirements specified in 8 5 141.11.
141.23.141.24.141.32.141.40.141.61 and
141.62 must contain the following (in
addition to the general primacy
requirements enumerated elsewhere in
this Part including the requirement that -
State regulations be at least as stringent
as the federal requirements):

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31848
Federal Ragbter  / Vol. 57. No. 138  / Friday. July 17. 1992  / Rules  and Regulations
  (2) A monitoring plan for the initial
monitoring period by which the State will
assure all system* complete the required
initial monitoring within the regulatory
deadlines.
  Not*: States may update their monitoring
plan submitted under the Phase II Rule or
§ imply note in their application that they will
use the same-monitoring plan for the Phase V
Rule.
  (!) The Initial monitoring plan must
describe how systems will be scheduled
during the initial monitoring period and
demonstrate that the analytical workload on
                             certified laboratories for each of the three
                             years has been taken into account, to assure
                             that the State's plan will result in a, high
                             degree of monitoring compliance and that a*
                             a result there is a high probability of
                             compliance and will be updated as
                             necessary.
                               (ii) The State must demonstrate.that the..
                             initial monitoring plan is enforceable under
                             Slate law.

                               3. Section 142.62 is amended by
                             revising paragraphs (a) and (b) to read
                             as follows:
§ 142.62  Variance* and exemption* from
the maximum contaminant levels for
organic end Inorganic chemicals.
  (a) The Administrator, pursuant to
section 1415(a){l)(A) of the Act hereby
identifies the technologies listed in
paragraphs (a)(l) through (a)(54) of this
section as the best technology. •••
treatment techniques, or other means
available for achieving compliance with
the maximum contaminant levels for
organic chemicals listed in § § 141.61 (a)
and (c):
                                       Contaminant
                                                                                                    Best available technologies
                                                                                              PAT '
                                                                                                            GAO1
                                                                                                                          OX'
                                                                                           X
(2> Carcon tttrachtood*.						  X
(3) 1.2-Dichloroothaoe.				—	-	  X
(4) Tnchkxoetftyleoe,	•			  X
(5) gara-OicMorooanzeno		-	-					—~	  X
(6) 1.1-OiChlOfO««>yten«		_					j X
(7) 1.1.1-Tncnkxoethana						-			  X
(8) Wtyt crrfonda	...™			-.«..	~..—	  X
(9) os«1.2-OicNofo*triyi*oo..-...«.	•...«	«.	-	-	-	  X

-•  • -'                                             ""	                                ~  x
(12) MooocWofobenzena	-	••	  X

                                                                                           X
(15) T»tracnkXO«kx	
(33) PCSs	„	
(34) Panlacnlofoph«nol...
(35) Tonaphorvo,,,.	,	
(36) 2.4.S-TP	„		
(37) 8*nzota]pyrena —
(38) Oatapona,		

(40) r>(2-«t»»y1b«!Eyt)ado«»«		_	  X
(41) O(2-clhy)heiyl)pwnalalo,.
(42) &oosab	.«	
(43) CVy^if^      i
(44) Eretotnax	
(45) Endnn..„........_.._...,..___,.
(46) GlypfOMte.............	_,.
(47) Hatactvkxobenzene	
(48) HaxacWofocyclopofltad^na	  _              	_....	_«..««......«.	,,,   ,	, -,-  x
(49) Oxamy< (VydaM).
(SO)P>ekxam,	

(52) 1^.4-TnerJocoo«oMoe					3 X
(53) 1.1J!'Tnchloroe«>a«t		~	-	..'....
(5«) 2.3.7,8-TCOO (Ocxjn)	
    1 Packad Toww Aarabon
    'GranO* ActrvmXd Cannon
    'Ouda&on (CNoonaton or Otonaao^
   (b) The Administrator, pursuant to
section 1415(aXl)(A) of tha Act, hsreby
                              identifies "tha following as the best
                              technology, treatment technique*, or
other means available for achieving
compliance with the maximum

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Federal Register / Vol. 57, No. 138 / Friday, July 17, 1992 / Rules and Regulations
31849
contaminant levels for the inorganic
chemicals listed in 5 141.62:
BAT FOR INORGANIC COMPOUNDS LISTED
IN M 4 1.62(8)
Chemical name . BATts)
Antimony*. 	 - 	 	 	 .







Nickel 	 • 	 '
2.7
2.3.8
5.6.7.9
1.2.5.6.7
2.5.6.7
2.5.6 '.7
5.7.10
2 '.4.6 \7 '
5.6.7
BAT FOR INORGANIC COMPOUNDS
IN « 1 4 1 .62(8)— Continued
LISTED
Chemical name j 8AT(s)
Nitrite 	 I


Thallium 	 	 ~ 	 . 	 - 	 |.
1 BAT only if influent Hg concentrations
1 SAT (of Chromium III only.
5 BAT lor Selenium IV only.
Key to BATS in Table
1 = Activated Alumina •
5.7.9
5.7
1 2 '.6.7.9
1.5
-.10*19/1
2=Coagulation/Filtration (not BAT for
systems < 500 service connections)
3 = Direct and Diatomite Filtration
4 = Granular Activated Carbon
5 = Ion Exchange
8= Lime Softening (not BAT for systems
< 500 service connections)
7 = Reverse Osmosis
8=CorroBkm Control • - •
9 = Electrodialysis
10 = Chlorine
11 = Ultraviolet
[FR Doc. 92-15580 Filed 7-16-92; 8:45 amj
BILLING COOf 8MO-SO-M

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