United States
               Environmental Protection
               Agency
                Office of Water
                Regulations and Standards
                Criteria and Standards Division
                Washington DC 20460
EPA 440/5-80-033
October 1980
c/EPA
Ambient
Water Quality
Criteria for
Chloroform

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      AMBIENT WATER QUALITY CRITERIA FOR

                CHLOROFORM
                 Prepared By
    U.S.  ENVIRONMENTAL PROTECTION AGENCY

  Office  of Water Regulations and Standards
       Criteria and Standards Division
              Washington, D.C.

    Office of Research and Development
Environmental Criteria and Assessment Office
              Cincinnati, Ohio

        Carcinogen Assessment Group
             Washington,  D.C.

    Environmental Research Laboratories
             Corvalis, Oregon
             Duluth, Minnesota
           Gulf Breeze, Florida
        Narragansett, Rhode  Island

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                              DISCLAIMER
      This  report  has  been reviewed by  the  Environmental  Criteria and
Assessment Office,  U.S.  Environmental  Protection  Agency,  and approved
for publication.   Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
                          AVAILABILITY  NOTICE
      This  document  is available  to  the public  through  the National
Technical Information Service, 1NTIS), Springfield, Virginia  22161.
                                     11

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                               FOREWORD

    Section 304  (a)(l)  of  the Clean Water Act  of  1977 (P.L.  95-217),
requires the Administrator  of the Environmental Protection Agency to
publish  criteria  for water  quality accurately reflecting  the  latest
scientific knowledge on  the  kind  and extent of all identifiable effects
on  health  and  welfare  which  may  be  expected from  the presence  of
pollutants in  any  body of water, including ground water.  Proposed water
quality criteria  for the 65  toxic  pollutants  listed  under section 307
(a)(l)  of  the  Clean Water  Act  were developed  and  a notice  of their
availability was published for public comment on March 15, 1979 (44 FR
15926), July 25, 1979 (44 FR  43660), and  October 1,  1979 (44  FR 56628).
This document  is  a revision  of  those  proposed criteria  based  upon  a
consideration  of  comments received  from  other  Federal  Agencies, State
agencies,  special  interest  groups,  and  individual  scientists.   The
criteria contained in this document replace any previously published EPA
criteria  for  the  65 pollutants.    This criterion  document  is  also
published in satisifaction of paragraph 11 of the Settlement Agreement
in  Natural  Resources  Defense Council,  et.  al.  vs. Train,  8  ERC 2120
(D.D.C. 1976), modified, 12 ERC 1833 (D.D.C.  1979).

    The term "water  quality criteria"  is used  in  two  sections  of the
Clean Water Act, section 304  (a)(l)  and section 303 (c)(2).  The term has
a different program  impact  in each  section.   In section  304,  the term
represents a non-regulatory,  scientific  assessment of ecological  ef-
fects.  The criteria presented  in  this  publication  are  such  scientific
assessments.   Such water  quality  criteria  associated with  specific
stream uses when adopted as  State water quality  standards under section
303 become  enforceable  maximum  acceptable  levels  of  a  pollutant  in
ambient waters.  The water quality criteria adopted in the State water
quality standards could have the same numerical  limits as the  criteria
developed under section  304.  ,','owever, in many situations States may want
to adjust water quality  criteria  developed under section 304 to reflect
local   environmental  conditions  and  human  exposure  patterns  before
incorporation   into  water quality  standards.    It  is  not until  their
adoption as part of the  State water  quality standards that the criteria
become regulatory.

    Guidelines  to assist the  States  in  the modification of  criteria
presented  in   this  document,  in  the  development  of  water  quality
standards, and in  other  water-related programs of this Agency, are being
developed by EPA.
                                    STEVEN SCHATZOW
                                    Deputy Assistant Administrator
                                    Office of Water Regulations and Standards
                                   111

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                              ACKNOWLEDGEMENTS
Aquatic Life Toxicology:

    William A. Brungs, ERL-Narragansett
    U.S. Environmental Protection Agency

Mammalian Toxicology and Human Health Effects:

    Leland J. McCabe, HERL (author)
    U.S. Environmental Protection Agency

    Debdas J. Mukerjee (doc. mgr.)
    ECAO-Cin
    U.S. Environmental Protection Agency

    Jerry F. Stara (doc. mgr.) ECAO-Cin
    U.S. Environmental Protection Agency

    Patrick Durkin
    Syracuse Research Corporation

    Roy E. Albert*
    Carcinogen Assessment Group
    U.S. Environmental Protection Agency
David J.  Hansen,  ERL-Gulf Breeze
U.S. Environmental  Protection Agency
Julian Andelman
University of Pittsburgh

Herbert Cornish
University of Michigan
Joseph Borzelleca
Medical College of Virginia

Steven D.  Lutkenhoff,  ECAO-Cin
U.S. Environmental Protection Agency

Si Duk Lee,  ECAO-RTP
U.S. Environmental Protection Agency
Technical Support Services Staff:  D.J.  Reisman,  M.A.  Garlough,  B.L.  Zwayer,
P.A. Daunt, K.S. Edwards, T.A. Scandura, A.T.  Pressley,  C.A.  Cooper,
M.M. Denessen.

Clerical Staff:  C.A.  Haynes, S.J.  Faehr, L.A.  Wade,  D.  Jones, B.J. Bordicks,
B.J. Quesnell, C. Russom, B.  Gardiner.


*CAG Participating Members:
    Elizabeth L. Anderson, Larry Anderson, Dolph Arnicar,  Steven Bayard,
    David L. Bayliss, Chao W. Chen, John R. Fowle III, Bernard  Haberman,
    Charalingayya Hiremath, Chang S. Lao, Robert McGaughy,  Jeffrey Rosen-
    blatt, Dharm V. Singh, and Todd W. Thorslund.
                                  IV

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                           TABLE OF CONTENTS
Introduction                                               A-l

Aquatic Life Toxicology                                    B-l
     Introduction                                          B-l
     Effects                                               B-l
          Acute Toxicity                                   B-l
          Chronic Toxicity                                 B-l
          Miscellaneous                                    B-2
          Summary                                          B-2
     Criteria                                              B-3
     References                                            B-7

Mammalian Toxicology and Human Health Effects              C-l
     Exposure                                              C-l
          Ingestion from Water                             C-l
          Ingestion from Food                              C-3
          Inhalation                                       C-4
          Dermal                                           C-5
     Pharmacokinetics                                      C-5
          Absorption                                       C-5
          Distribution                                     C-6
          Metabolism                                       C-6
          Excretion                                        C-9
     Effects                                               C-9
          Acute, Subacute and Chronic Toxicity             C-9
          Synergism and/or Antagonism                      C-l7
          Teratogenicity                                   C-18
          Mutagenicity                                     C-19
          Carcinogeniclty                                  C-20
     Criterion Formulation                                 C-29
          Existing Guidelines and Standards                C-29
          Current Levels of Exposure                       C-31
          Basis and Derivation of Criteria                 C-35
     References                                            C-41

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                               CRITERIA DOCUMENT
                                  CHLOROFORM
CRITERIA
                                 Aquatic Life
    The available data  for  chloroform  indicate that  acute toxicity to fresh-
water aquatic  life occurs at  concentrations  as  low as  28,900 yg/1, and would
occur at lower concentrations  among  species  that  are more sensitive than the
three tested  species.   Twenty-seven-day  LCgn values  indicate that  chronic
toxicity occurs  at concentrations  as low as  1,240 yg/1,  and could  occur  at
lower concentration  among species or  other  life  stages  that  are  sensitive
than the earliest life cycle stage of the rainbow trout.
    The data base for saltwater species  is  limited to  one test and no state-
ment can be made concerning  acute or  chronic toxicity.

                                 Human  Health
    For  the   maximum  protection  of  human  health   from  the   potential
carcinogenic  effects  due  to  exposure of  chloroform through  ingestion  of
contaminated  water  and  contaminated  aquatic  organisms,  the  ambient  water
concentrations should be zero  based  on  the  non-threshold  assumption for this
chemical.   However,  zero level may  not  be  attainable at the  present  time.
Therefore,   the  levels  which  may result  in  incremental  increase  of  cancer
risk  over   the  lifetime  are  estimated  at  10~5,   10   ,   and  10  .    The
corresponding recommended criteria are 1.90  yg/1,  0.19 ug/1,  and  0.019  yg/1,
respectively.   If  the  above  estimates  are  made  for  consumption  of  aquatic
organisms   only,  excluding  consumption  of water,  the  levels  are  157  ug/1,
15.7 ug/1,  and 1.57 ug/1, respectively.
                                      VI

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                                 INTRODUCTION







    Chloroform  (CHC1-)  was first  employed  as  an  anesthetic agent  in  1847.



Only  a  small amount  was necessary  to  induce  narcosis,  and its  action  was



more  complete than  ether.   Today,  it has been  replaced  by other anesthetics



with  more desirable properties;  but  it  is used widely as  a  chemical  solvent



and  as  an  intermediate  in  the  production  of  refrigerants,  plastics,  and



Pharmaceuticals  (U.S.  EPA,  1975).   Current  annual  production of  chloroform



approaches 120,000 metric tons (U.S. EPA, 1977).



    Chloroform  (CHCl^;  molecular  weight 119.39),  at ordinary  temperatures



and  pressures,   is  a  clear,   colorless,  volatile  liquid with  a  pleasant,



etheric, nonirritating  odor  and sweet taste  (Hardie,  1964;  Windholz,  1976).



It has  a boiling  point  range  of  61-62'C,  a  melting point  of -63.5"C,  and  is



nonflammable.   There   is no  flash  point  (Hardie,   1964;  Windholz,  1976).



Chloroform  is   slightly soluble  in  water  (7.42  x  106  pg/1   of water  at



25°C).  It is miscible  with alcohol,  benzene,  ether,  petroleum ether,  carbon



tetrachloride,   carbon  disulfide, and oils  (Windholz, 1976).  Chloroform  is



highly  refractive  and  has a  vapor  pressure  of 200  mm  Hg  at   25°C  (Irish,



1962; Windholz,  1976).   Because of  its  volatile nature,  chloroform has  the



potential  for  evaporation to  the  air  from  pollution  sources   or from  the



water column.



    At  ambient  environmental  temperatures,  chloroform  is  thermostable  and



resists  decomposition   (Hardie,  1964).   However,  slow decomposition  occurs



following  prolonged exposure to  sunlight  and  in darkness  when  air  is present



(Hardie, 1964).   Chloroform has  the  potential  to react  with, and thereby de-



plete,  the ozone  layer; studies  have shown that phosgene is a  decomposition
                                     A-l

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product of ozone  and  chloroform  (Hardie,  1964).   There  is  no appreciable de-
composition of chloroform at ambient temperatures  in water,  even  in  the pre-
sence of  sunlight (Hardie,  1964),   Aqueous degradation of chloroform  is ac-
celerated in  the  presence  of aerated waters and  metals,  such as  iron,  with
hydrogen peroxide representing a reaction product (Hardie,  1964).
    Chloroform appears to be ubiquitous  in  the environment in  trace  amounts,
and  discharges  into  the  environment  result  largely  from  chlorination  of
water and wastewater (U.S.  EPA, 1975).
                                     A-2

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                                  REFERENCES








Hardie,  D.W.F.   1964.    Chlorocarbons  and  Chlorohydrocarbons:  Chloroform.



ln_:  D.F.  Kirk and  D.E.  Othmer (eds.).  Encyclopedia  of Chemical Technology.



2nd ed.  John Wiley and Sons,  Inc., New York.







Irish,  D.D.   1962.   Aliphatic Halogenated  Hydrocarbons.   j_n:  Industrial Hy-



giene and Toxicology.  2nd ed.  John Wiley and Sons,  Inc., New York.







U.S.  EPA.   1975.   Development document  for  interim final  effluent limita-



tions  guidelines  and new  source  performance  standards for the significant



organic  products  segment  of the organic  chemical  manufacturing  point source



category.  EPA 440/1-75-045.  U.S.  Environ. Prot. Agency, Washington, D.C.







U.S.  EPA.   1977.    Determination of  sources of  selected chemicals  in  water



and amounts from  these  sources.   Area 1.  Task  2.   Draft  final  report.   Con-



tract No. 68-01-3852.  U.S. Environ. Prot. Agency,  Washington,  D.C.







VJindholz, M.  (ed.)   1976.   The Merck Index.   9th  ed.  Merck  and  Co.,   Inc.,



Rahway, New Jersey.
                                      A-3

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Aquatic Life Toxicology*

                                  INTRODUCTION

    Chloroform has  been most  commonly tested  under static conditions with no

measurement  of  the concentrations of  chloroform to which  the  organisms are

exposed.   Consequently,  the  acute  toxicity  data  base will  probably under-

estimate  the  toxicity because concentrations  in static tests  are  likely to

diminish  during  the progress  of  the exposure  as  a result of loss from water

to air.

                                    EFFECTS

Acute Toxicity

    A 48-hour  static  test with  Daphnia  magna resulted in  an LCcn  of 28,900

yg/1 (Table 1).   Bentley,  et  al. (1975) compared  the  toxicity  of chloroform

to rainbow trout  and  to bluegill  and  found  (Table  1) that the trout was more

sensitive.   All   96-hour   LC5Q   values   for   freshwater  fish,  using  static

methods and unmeasured concentrations, were between 43,800 and 115,000 ug/1.

    Only  one  appropriate   acute  test has  been  reported  on the  toxicity of

chloroform to  saltwater  aquatic  life.   Bentley,  et  al.  (1975)  conducted  a

static test  with  pink shrimp and determined  a 96-hour IC™  value  of 81,500

ug/1 (Table 1).

Chronic ^oxicity

    No chronic effects of  chloroform on freshwater  or  saltwater  species are

available other than those in  Table 3.
*The reade^  is referred  to  the Guidelines  for Deriving Water  Quality Cri-
teria for the Protection of Aquatic Life and  Its  Uses  in  order to better un-
derstand the  following  discussion  and  recommendation.   The  following tables
conta-'n the  appropriate  data  that  were found  in  the literature,  and  at the
bottom of each  table are calculations  for deriving  various  measures of tox-
icity as described in the Guidelines.
                                      B-l

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Residues
    After a  14-day  exposure  (U.S.  EPA,  1978)  to radiolabeled chloroform, the
bluegill bioconcentrated chloroform by  a factor  of  6  times  (Table  2)  and the
tissue  half-life  was less than  1  day.   This  degree  of  bioconcentration and
short biological  half-life  suggest that residues of  chloroform  would  not be
an environmental hazard to consumers of aquatic life.
Miscellaneous
    Most of  these data  are compiled from  short exposures of minutes to a few
hours in duration  (Table  3).  With stickleback, goldfish,  and  orangespotted
sunfish, anesthetization  or  death  occurred at  concentrations  between  97,000
and 296,640  ug/1.   Birge, et  al.   (1979)  conducted flow-through  tests  with
measured chloroform  concentrations in closed  systems.   Exposures  of  rainbow
trout began within 20 minutes  after fertilization and  ended eight  days after
hatching.  There  was no additional mortality  between the  fourth  and  eighth
days  after  hatching.  The 27-day  IC™  values  for  soft  and hard  water  were
2,030 and  1,240 ug/1,  respectively.   There was  a  40  percent   incidence  of
teratogenesis in the embryos  at hatching.
Summary
    Two freshwater fish and  one  invertebrate species  have  been  acutely test-
ed under standard  conditions  and  50  percent  effect concentrations were be-
tween 28,900 and  115,000 ug/1.   Embryo-larval tests  with  rainbow trout  at
two  levels   of  hardness  provided   27-day  LCro  values  of  2,030  and  1,240
ug/1.  There was a 40 percent  occurrence of teratogenesis  after  a  23-day ex-
posure  of  rainbow  trout  embryos.   The  equilibrium  bioconcentration  factor
for the  bluegill  was 6, which indicates that  residues  should  not be  a  pro-
blem in the aquatic ecosystem.
                                      B-2

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    Only  one test  has  been conducted  with  chloroform and  saltwater organ-
isms.  The 96-hour  LC5Q for the pink shrimp was 81,500 ug/1.
                                   CRITERIA
    The available data  for  chloroform  indicate  that  acute toxicity to fresh-
water aquatic life  occurs at concentrations  as  low as  28,900 ng/1, and would
occur at  lower  concentrations  among  species  that  are more sensitive than the
three  tested species.   Twenty-seven-day LC^g  values  indicate  that  chronic
toxicity  occurs  at  concentrations  as low as  1,240 yg/1,  and could  occur  at
lower  concentrations  among species  or  other  life  stages that  are  more
sensitive than the earliest life cycle stage of the rainbow trout.
    The data base for  saltwater species  is  limited to  one test and no state-
ment can be made concerning acute and chronic toxicity.

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                            TabUi  1.  Acuttt value*  for chloroform
Spocles
            LC3iO/EC!!iO
Method*      (Vi
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           TabI« 2.  Residues  for chloroform (U.S. EPA, 1978)
Species
Blueglll,
Lepomls nacrochlrus
                Bloconcantratlon
   Tlssut            Factor
FRESHWATER SPECIES

 whole body
Duration
 (day*)
   14
                                B-5

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                             TobU 3.  Oth«r data for chloroform
Species
Rainbow trout
   (embryo-larva I),
Salmo galrdnorI

Rainbow trout
   (ombryo- larva I ),
SaImo ijalrdnerI

Rainbow trout (ombryo),
Sa I mo ga Irciner I

Orangespotted sunflsh,
Lepomls humlI Is

Goldfish,
Uarass I us juratus

Threesplne stickleback,
Gasterosteus aculeatus

Nlnesplne stickleback,
Pungltlus pungitlus
Duration          Effect

         FRESHWATER SPECIES
                                                               Result
 27 days     LC50 at 50 mg/l
             hardness
 21 days     LC50 at 200 mg/l
             hardness
  1 hr


30-60 mln


 90 mln
  2,030
                                blrge,  et al.  1979
                      1,240     Blrge, et al.  1979
 23 days     40J teratogenes I s    10,600     Ulrge, el al.  1979
Death


50J anesthetized


Anesthesia with
recovery

Avoldance
106,890-
152,700

 97,000-
167,000
                                 146,320-
                                 296,640*
Cloyberg, 1917
Gherkin i Catchpool,
1964
207,648»    Jones,  I947a
                                Jones, 1947b
* Corrected from vol/vol to
                                            B-6

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                                  REFERENCES

Bentley,  R.E.,  et  al.   1975.   Acute  toxicity  of  chloroform  to  bluegill
(Lepomis  macrochirus),  rainbow  trout,  (Salmo  gairdneri),  and  pink  shrimp
(Penaeus  durprarum).    Contract   No.  WA-6-99-1414-B.   U.S.  Environ.  Prot.
Agency.

Birge, W.J.,  et al.   1979.   Toxicity  of  organic chemicals  to  embryo-larval
stages of fish.  EPA-560/11-79-007.  U.S.  Environ. Prot.  Agency.

Gherkin,  A. and  J.F. Catchpool.   1964.  Temperature  dependence of  anesthesia
in goldfish.  Science.   144: 1460.

Clayberg,  H.D.   1917.    Effect  of ether  and chloroform  on certain  fishes.
Biol. Bull.  32: 234.

Jones, J.R.E.   1947a.   The oxygen consumption  of Gasterosteus aculeatus  L.
to toxic  solutions.   Exp. Biol.  23:  298.

Jones, J.R.E.    1947b.    The  reactions  of  Pygosteus  pungitius L.  to  toxic
solutions.  Jour. Exp.  Biol.  24: 110.

U.S.  EPA.   1978.   In-depth studies  on health  and  environmental   impacts  of
selected  water  pollutants.  U.S.  Environ. Prot. Agency,  Contract  No.  68-01-
4646.
                                      B-7

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Mammalian Toxicology and Human Health Effects



                             EXPOSURE



Ingestion from Water



     In  an  80-city  study,  chloroform  was  found  in  all finished



drinking  water  supplies produced  from  raw  water which  had been



chlorinated (Symons, et al.  1975).   Chloroform usually was found  in



the highest  concentration  among the  four  trihalomethanes usually



detected.   In  finished drinking  water supplies,  the respective



levels of chloroform,  bromodichloromethane,  dibromochloromethane,



and bromoform ranged from less than 0.1  jug/1  to  311 ug/1,  undetect-



ed up to 116 iig/1, undetected up to 100 Jug/1, and undetected up  to



92 ug/1.   The highest concentrations of  total trihalomethanes were



found in finished drinking water supplies  for which  surface water



was used  as  the source; the  source  water  was chlorinated and the



free chlorine residual  from this chlorination was greater than 0.4



mg/1.   Total  trihalomethane  concentrations were generally related



to the organic  content  of  the raw water  when sufficient chlorine



was added  to create  a  chlorine   residual.   Analysis  of the raw



source waters  showed  only minor  contributions  to  the chloroform



levels of the finished  drinking waters,  thereby  inferring the pro-



duction of chloroform in the chlorination process.



     In  its Statement of Basis and Purpose for  an Amendment  to the



National  Interim  Primary Drinking Water  Regulations  for Trihalo-



methanes, 1978,  the  U.S. EPA  (1978b)  reviewed  the latest data  on



chloroform exposure  from drinking  water.    Data  derived from the



National Organics  Monitoring Study  (NOMS)  (U.S.  EPA,  1977)  noted
                               C-l

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that with an average per capita consumption figure of 2 liters per



day and 100 percent body absorption of chloroform, a total chloro-



form  uptake  from water  was estimated  to  be  a  mean value  of 61



mg/year and maximum value  of  343  mg/year.   The corresponding NOMS



mean and maximum chloroform concentrations for drinking water were



0.083 mg/1 and 0.47 rag/1.



     Additional evidence  of chloroform production as  a result of



chlorination practices in water renovation was provided by Bellar,



et al.  (1974).  Chloroform concentrations  in the influent and ef-



fluent of the Cincinnati,  Ohio  sewage  treatment plant where chlori-



nation was practiced were 9.3 ug/i and 12.1 ug/'l, respectively.



     Much higher levels of chloroform  have been found in wastewater



effluents and  also  as  the result of accidental industrial spills.



Wastewater effluents   from  rubber and  chemical  companies  in the



Louisville, Kentucky  area have  had  chloroform levels  as  high as



22,000 ug/1 (National Academy of  Sciences (NAS), 1978a).  An  acci-



dental  spill  into  the  Mississippi River was  studied in detail by



Neely,  et  al.   (1976);  the damage  involved  the  rupturing  of two



barge tanks and the release of 1.75 million pounds (0.79 x 10   kg)



of chloroform.   Numerous spills  have been detected  in the  upper



Ohio River (Thomas, 1979), and levels  of 50 ug/1  persisted for five



days in March  1978.  Both of these rivers serve as raw water sources



for finished drinking  water supplies,  and  it  is  obvious that  these



incidences contributed abnormally high exposure  of  chloroform  to



the human population.
                               C-2

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Ingestion from Food



     McConnell, et al. (1975) reviewed the  incidence,  significance,



and movement of chlorinated  hydrocarbons  in the food chain.  They



concluded that chloroform  is widely distributed  in  the environment



and is  present  in fish,  water birds,  marine  mammals, and  various



foods.



     A bioconcentration factor (BCF) relates the concentration of a



chemical  in  aquatic  animals  to the concentration  in  the water in



which  they  live.   The steady-state BCFs  for  a lipid-soluble com-



pound in the tissues  of various aquatic animals  seems  to  be  propor-



tional  to the  percent lipid  in the tissue.   Thus,  the per capita



ingestion of a lipid-soluble  chemical  can  be estimated from  the per



capita consumption of fish  and  shellfish, the weighted average per-



cent lipids of consumed fish and shellfish, and a steady-state BCF



for the chemical.



     Data from a recent survey on  fish and  shellfish consumption in



the United  States was analyzed by SRI International  (U.S.  EPA,



1980).  These data were  used  to estimate  that the per capita con-



sumption  of  freshwater and  estuarine  fish and shellfish  in the



United  States  is  6.5  g/day  (Stephan,  1980).    In addition,  these



data were used  with data on the fat content  of  the edible  portion of



the same  species  to estimate  that  the weighted  average  percent



lipids for consumed  freshwater and estuarine fish and shellfish is



3.0 percent.



     A measured steady-state  bioconcentration factor of 6  was ob-



tained  for chloroform  using  bluegills (U.S. EPA,  1978a).   Similar



bluegills contained  an  average of  4.8 percent  lipids  (Johnson,
                               C-3

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1980).  An adjustment factor of 3.0/4.8 = 0.625 can be used to ad-



just  the measured BCF from  the  4.8  percent  lipids of the bluegill



to the 3.0 percent lipids that  is  the  weighted  average for consumed



fish  and  shellfish.   Thus,  the weighted  average bioconcentration



factor for chloroform and the edible portions of  all  freshwater and



estuarine aquatic organisms consumed  by Americans is calculated  to



be 6  x 0.625 = 3.75.



      In food,  the  typical range of chloroform was  1 to 30 wg/kg.



The  highest  concentration  noted  was  in  Cheshire  cheese,  at   33



ug/kg.  It was concluded  that  chloroform  levels  in food would not



be acutely  toxic to  humans.    Pearson  and   McConnell  (1975)  also



reviewed the incidence of chlorinated hydrocarbons in various mar-



ine organisms and water birds and found that the concentrations  of



chloroform in edible fish and marine organisms  ranged from  3  to 180



ug/kg.



      Potrepka  (1976)  estimated that  the  consumption  of products



such  as  bread  derived   from  chloroform-treated  (as a  fumigant)



grains would contribute 0.56 ug of chloroform per day to the adult



human diet.  This  number  was  derived  assuming: (1)  consumption  of



140 g of  bread per  day,  (2) a chloroform level of 0.4 ^ig/g  in the



bread where  chloroform was  used  as  the  grain  fumigant,  and (3)



chloroform comprises only one percent of total fumigant  use  in the



United States.



Inhalation



      The National Academy of Sciences (NAS,  1978a) provided data  on



the  occurrence of  six  halomethanes  in the air.  The general  back-



ground   tropospheric   concentration  of  chloroform  ranged   from
                                C-4

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9.8 x  10   to 19.6 x 10  mg/m  , with higher concentrations in mar-



ine air;  lower  levels  were  normally found in continental air sam-



ples.  Over urban areas, there can be higher  concentrations  of car-



bon  tetrachloride,  chloroform, and methylene  chloride.   Bayonne,



N.J. had  the highest measured  ambient air concentration of  chloro-



form at 0.073 mg/m  .   Automobile  exhausts have been implicated  in



high urban area chloroform  concentrations.   Typically, automobile



exhausts  have chloroform levels of  0.027 mg/m  .  The concentration



of chloroform in indoor air rarely  exceeds 4.9 x 10~ mg/m .



Dermal



     At one  time,  chloroform  was  administered as an anesthetic  by



absorption through  the  skin.   The  American  Conference of Govern-



mental Industrial Hygienists (ACGIH, 1977)  has stated the potential



danger of percutaneous  chloroform  poisoning.   Today,  dermal expo-



sure is rare  and is applicable to  the small segment of the  popula-



tion engaged  in  the  manufacture and use  of chloroform and its prod-



ucts.



                        PHARMACOKINETICS



Absorption



     Chloroform is well absorbed via the respiratory system  (49  to



77 percent).    In an  early  study  by  Lehman  and  Hasegawa  (1910),



chloroform required 80  to 100 minutes to reach equilibrium  between



blood concentration and inhaled air concentration.  Chloroform ab-



sorption  from the  gastrointestinal tract approximates 100  percent



(Fry,  et  al.  1972).



     Inhalation studies of CHC1, in experimental animals have been



summarized by von Oettingen (1955).  At an exposure level of 8,000
                               C-5

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ppm of CHC1.,, mice were dead within three  hours,  and  at 12,500 ppm,



animals died within  two  hours.   At high levels of exposure, anes-



thesia occurred  within a few minutes,  indicating rapid absorption



and distribution via the respiratory  system.  Gastrointestinal ab-



sorption  was slower,  but  lethal tissue  levels  could  be attained



within minutes to a  few hours, depending  on the dose.  Fry, et al.



(1972) reported  that gastrointestinal absorption approximates 100



percent.



Distr ibution



     Being a  lipid  soluble compound,  CHC1, passes readily  through



cell membranes (primarily  by  simple diffusion)  and  easily  reaches



the central nervous system to produce  narcosis,  an effect  common to



most  of   the  halogenated  hydrocarbon  solvents  (Cornish,  1975).



Cohen and Hood (1969) demonstrated the long-term retention of CHC13



in body  fat,  with  increased levels occurring  in  liver  during the



post-exposure period.   Thus, there is  redistribution  of CHC1., in



body tissues  as  it slowly  builds  up  in  fatty  tissues  during the



post-exposure period.



Metabolism



     As  early  as 1964, Van  Dyke,  et  al.  (1964) demonstrated that



labeled CO- appeared in expired  air less  than an  hour after an in-


           14
jection of   C-labeled chloroform.  This amounted to  4  to  5  percent



of the total dose being exhaled  as C02 over  the  subsequent 12 hours



and  about 2 percent  exhaled as  other  labeled  metabolites.  This



represents considerable metabolism of a  relatively  inert chemical



solvent.   Other  unidentified metabolites  also were reported  in the



urine during  this  early study.    The  chloride  ion (JOC1) also has
                               C-6

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been  found  in  the  urine  of rats after the intraperitoneal dose of



labeled CHC13.



      It has  been  suggested that the formation of CO- results  from



the degradation of CHC1., to methylene chloride (CH-Clj) and thence



to  formaldehyde,   formic  acid,  and  CO-  (Rubenstein  and  Kanics,



1964).  However,  the  formation  of  CH2C12  has not been well estab-



lished.



      Scholler  (1970) reported that the hepatotoxicity of chloroform



was markedly enhanced by  phenobarbital,  a  known inducer  of  the



mixed  function oxidase  (MFO)  system.   Conversely a  decrease in



hepatotoxicity of  CHCl^  occurred  in  animals pretreated  with  SKF



525-A, an  inhibitor  of  the MFO  enzyme  system (Gopinath and Ford,



1975).  Chloroform metabolism depleted liver glutathione, and  this



depletion was  stimulated by liver microsomal enzyme inducers,  such



as phenobarbital (Ilett,  et al.  1973).  These  authors also reported



that  after  phenobarbital treatment there  was an  increased biliary



excretion of labeled metabolites of   CHC1, in the bile of rats.



     The formation of a chemically reactive CHC1-,  metabolite, which



may bind covalently to tissue macromolecules, has been reported by



several  investigators  (Ilett,  et  al.  1973;  Uehleke  and  Werner,



1975).  Covalent  binding  in  both  liver and  kidney  was increased



following microsomal enzyme induction.  In vitro  studies  (Ilett, et



al. 1973)  indicated that  the  formation of CHC1- metabolites capable



of covalent binding is NADPH-dependent and inhibited  by  carbon  mon-



oxide.  There  is a suggestion that a different or additional path-



way of metabolism  also may operate  in the kidney, since  there  is  a
                               C-7

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minimal  requirement  for  NADPH  and no requirement for 0- in the  in
                                                       £         ——
vitro microsomal system.
     Recent reports have shown the in vitro formation of  a systemic
metabolite  of  chloroform   (2-oxothiazolidine-4-carboxylic   acid)
during incubation with liver microsomes  (Pohl, et al. 1977).  This
compound  is  readily  formed  by the reaction  of  cysteine and  phos-
gene, raising  again  the  suggestion of phosgene as an intermediate
in the metabolism of chloroform.   Pohl (1979) suggested  the  initial
formation  of  unstable trichloromethanol via the  cytochrome  P450
system,  spontaneous elimination of HC1 to yield the  reactive  phos-
gene which binds  with cysteine  and   other  tissue macromolecules.
The author also reported  data indicating  that deuterium (D)-labeled
chloroform (CDC1-,)  was less  toxic  and  less  readily metabolized than
CHC1.,, suggesting  that the  cleavage   of  the  C-H  bond is the  rate-
limiting  step  in  the  process  resulting  in  the  hepatotoxicity  of
chloroform.   Free  radical  formation  also  has been  proposed  as  a
metabolic  pathway of CHC1, which would lead  to reactive  intermedi-
ates (Smuckler, 1976; Reynolds, 1977; Royer,  et al.  1978).
     As a  result of  these studies, it is  quite  apparent that  the
microsomal enzyme system plays an  important  role  in  the  metabolism
and toxicity of chloroform.   However,  several pathways and interme-
diates have been proposed as the  relevant ones.  Additional clari-
fication at the molecular level is still  necessary  to determine  the
operative  in vivo pathways involved in the  metabolism of  chloroform
in animals and  in man.
                               C-8

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Excretion



     Fry, et al. (1972) studied a group of adult  humans  who  ingest-



ed capsules containing 500 mg of    C-labeled  chloroform.  More  than



96 percent of the administered isotope was exhaled within 8 hours.



Unchanged chloroform was excreted  by this route with an efficiency



of 18 to 67 percent.   Less than one percent of  the  isotope appeared



in the urine.  Those people with a higher fat content exhaled  less



unchanged chloroform in the 8-hour period and presumably more  C02-



A  kinetic  analysis  of  Fry's  data on  two people  by  Chiou  (1975)



showed  that,  extrapolated  to  infinite time,  the  fraction  metab-



olized to CO- is 46 percent for a male  and 58 percent for a female,



and the rest is  exhaled as chloroform.  The half-life of chloroform



in the blood and in expired air is approximately 1.5 hours.



                             EFFECTS



Acute, Subacute, and  Chronic Toxicity



     Human exposure to  chloroform may be via  inhalation, ingestion,



or by cutaneous  contact (Gonzales, et  al. 1954;  Schroeder,  1965).



The first reported case of death  as a result  of  chloroform anes-



thesia-induced  liver   damage   occurred  in  1894   (Guthrie,  1894).



Toxic effects include  local irritation  (hyperemia, erythemia, mois-



ture loss)  at  the  site of  skin absorption  (Malten,  et al.  1968),



central  nervous system  depression,   gastrointestinal  irritation



(Challen, et al. 1958), hepatic and renal  damage,  and possible  car-



diac  sensitization   to  adrenalin   (Fuhner,  1923;  Althausen  and



Thoenes, 1932; Cullen, et  al.  1940).



     Chloroform is  considered to  be moderately  toxic.   It is sever-



al times more potent  than  carbon  tetrachloride as a depressant of
                               C-9

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the central  nervous system when  inhaled,  but clinical experience



suggests that it is less toxic  than  carbon  tetrachloride when taken



orally.  The ingestion  of 263 g has been possible, although inges-



tion of  much smaller amounts  has produced serious  illness.   The



mean lethal dose is approximately 44 g  (Gosselin, et al. 1976).



     The  National   Institute  for Occupational  Safety  and  Health



(NIOSH) Criteria Document  (1974)  contains  a tabulation of the ef-



fects of  chronic chloroform exposure on humans.   One 33-year-old



male,  who habitually had inhaled chloroform for  12 years, was noted



to have the psychiatric  and  neurologic symptoms of depression, loss



of appetite, hallucination,  ataxia,  and  dysarthria.  Other symptoms



from habitual use are moodiness, mental and physical sluggishness,



nausea, rheumatic pain,  and delirium.



     Most human  toxicological  data  have resulted from  the  use of



chloroform as a general anesthetic  in operations.  Delayed chloro-



form poisoning  has often occurred  after  delivery  in obstetrical



cases.   The delayed toxic effects were usually preceded  by a latent



period ranging from a few hours to  one day.   Initially drowsiness,



restlessness, jaundice,  and  vomiting occurred,  followed by fever,



elevated  pulse  rate,  liver  enlargement,  abdominal tenderness, de-



lirium,  coma,  and  abnormal findings  in liver and kidney function



tests were  also  reported.   Death often  ensued,  three  to ten days



post partum.  Autopsy reports generally  described the liver  as hav-



ing a bright yellowish  color,  fatty infiltration  with  necrosis was



found.  Other hepatotoxic effects have been reviewed  (NIOSH, 1974).



Numerous  animal studies have  shown that  chloroform causes  fatty



infiltration  and  necrosis  of  the  liver.   None  of  these  studies
                               C-10

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involved long-term exposures to low concentrations.  However, these
studies show  that  hepatotoxic  effects of chloroform  can occur as
the result of ingestion, inhalation, or intravenous administration
(NIOSH, 1974).   Although  the  causes  of  death  in  most  cases of
chloroform poisoning have been  attributed  to necrosis  of  the liver,
there also has been evidence at autopsy of  renal damage,  including
albumin and  red  blood cells in urine, elevated  blood urea,  an 18
percent decrease in prothrombin after surgery, and fatty degenera-
tion.
     A  case  of pulmonary  toxicity resulting  from  an intentional
intravenous  injection  of chloroform has been  reported  (Timms  and
Moser, 1975).  Chloroform poisoning has resulted in symptoms simi-
lar to  those  of marked hemolytic anemia.    Chloroform has induced
hemolysis of  human  erythrocytes  in vitro  (Belifore  and Zimmerman,
1970).
     Malten, et al. (1968) reported that chloroform exposure ulti-
mately results in an injury to only the horny layer of skin in hu-
mans,  and  that the  skin often  responds  with the  formation  of a
temporary protective barrier.
     There  have  been  few  studies of  industrial worker  exposure.
Challen, et al.  (1958)  reported a study of workers in  a confection-
ary firm in England that manufactured  medicinal lozenges.   In 1950,
the workers began to complain of chloroform vapor given off during
the  production  of   the  lozenges.   These workers were placed  on a
reduced work week  to alleviate  their complaints of lassitude, flat-
ulence, water brash (British term indicative of symptoms  of dyspep-
sia), dry mouth,  thirst, depression,  irritability, and frequent and
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"scalding" micturition.   This  action  was not  successful  and the



employees refused  to work on  that  particular  process.   In 1954, a



new team of operators was engaged and in 1955,  a system of exhaust



ventilation  was  installed,  after  which manufacturing  proceeded.



without interruption.



     Clinical  investigations  of  three  different groups of workers



in  this  manufacturing  plant  were  performed  by  Challen,   et al.



(1958).  One group of eight employees was termed the "long service



operators."  These were people who refused to continue in the loz-



enge  department after  they  experienced the  previously  described



symptoms.   This group of workers, when exposed  to chloroform vapor



in concentrations ranging from 376  to L,158 nig/m ,  had been observ-



ed staggering  about  the work  area.   After  terminating  work in the



lozenge department,  the  "long service  operators" reported experi-



encing nausea after even short exposures to chloroform.



     A second  group  of nine  employees,  termed  the "short service



operators," were the  replacements for the "long  service operators."



Two of these  nine  employees  did not report unpleasant experiences



from chloroform exposure.   Among  the  other  seven,  five  reported



dryness of the mouth  and throat at  work;  two were subject to lassi-



tude in the evening;  one complained of lassitude and flatulence at



work;   and  the  experiences  of two others were similar  to  those of



the "long  service operators."   The  "short service operators" worked



in locations where the chloroform concentrations ranged  from 112 to



347 mg/m3.



     A third  group of  five employees who  worked in other depart-



ments  of  the  firm served as  controls and exhibited  no symptoms.
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Tests  of liver  function (thymol  turbidity,  thymol  flocculation,



direct van den Bergh, and indirect serum bilirubin),  clinical  exam-



inations,  and  urinary  urobilinogen  failed  to  show  significant



differences among  the  three groups of  workers.



     Bomski, et al.  (1967) reported on liver injury from chloroform



exposure among workers  in a pharmaceutical  factory  in Poland.  The



study included the entire group of 295  workers who were exposed  to



chloroform in the course of production.  Of these, 68 were exposed



to chloroform for 1 to 4 years and still were in contact  with chlor-



oform, 39 had  chloroform contact at one time,  but were no longer



exposed, 23  had  viral  hepatitis  with  icterus  two  to three  years



earlier and were designated as posticterus controls  and were  work-



ing in a germ-free area, and  165  worked in  a germ-free area with  no



history  of  viral  hepatitis.   Blood  pressure,  blood morphology,



urinalysis,  blood  albumin,  serum  protein,  thymol turbidity,   zinc



sulfate  turbidity,  urobilinogen,  SCOT, and SGPT  were measured  in



all;  the  "Takata-Ara"  sulfate  (colorimetric)  test  was also   per-



formed.   A complete medical history was taken.   Sixty of the people



were hospitalized  for determination  of  BSP clearance and urinary



urobilinogen.



     The air  in  the  production  room  was  sampled,  and  chloroform



concentrations were determined with the Grabowicz  method.  The con-



centration of chloroform ranged from 9.8 to 1,002 mg/m  .  No  other



concentration measurements were reported, nor was  there  any mention



of the frequency of  sampling.



     The  authors  compared  the  frequency  of  viral  hepatitis and



jaundice among a group  of inhabitants  of the city, 18 years of age
                               C-13

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and older, with that of the  same  68  pharmaceutical workers who were



exposed to chloroform.  The results showed that in I960, 0.35 per-



cent of city  inhabitants  had  viral  hepatitis, while 16.67 percent



of the chloroform-exposed workers  had viral  hepatitis.   In 1961,



the frequency of viral hepatitis  for city inhabitants was 0.22 per-



cent, and the frequency among the chloroform workers was 7.50 per-



cent.  In 1962,  the  frequency  of viral hepatitis was 0.38 percent



for city  inhabitants and 4.4 percent for  workers exposed to chloro-



form.  The authors suspected that the  toxic liver changes occurring



as a result  of exposure to chloroform  promoted  a viral infection in



such cases, but  they  did  not  give  information on the incidence of



viral hepatitis among  the other groups of plant workers.  This in-



formation might have helped resolve questions about sanitary prac-



tices and facilities in the plant.



     The  majority of  the workers who  were in contact with chloro-



form during  the investigation period  covered in this  study com-



plained of headache, nausea, belching, and loss of appetite.  Among



the  68 workers  using  chloroform,   19  cases  of  splenomegaly were



found;  none was found  in the controls.



     The   frequency  of  enlarged  livers  (17  of 68)   among  workers



exposed  to  chloroform  exceeded  the  frequency  of  enlarged  livers



in  two of the other  groups  (5  of  39  and 2  of 23).   Livers were



judged to be enlarged  if they  extended at least 1 cm  beyond  the rib



arch in  the midclavicular  line.   The  upper  margin  was apparently



not measured.   In  3 of the  17 chloroform workers with enlargement



of  the liver,  toxic hepatitis was  diagnosed  on  the  basis of ele-



vated  serum  enzyme  activities and  elevated  serum  gairjna globulin,
                               C-14

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but  the  measured amounts  of  these serum  constituents  in these 3



workers were not reported.  In the remaining 14 cases of  liver en-



largement, fatty liver was diagnosed.



     Intraperitoneally-injected  chloroform can be  nephrotoxic  in



mice  (Klaassen  and  Plaa,  1967a).   The acute  LDcn  value  for male



mice was  1,800  mg/kg body weight;  for females,  1,900  mg/kg body



weight.  Male mice demonstrated renal dysfunction  at 116 mg/kg body



weight, but  females did  not exhibit  renal  dysfunction at  any time



during or after exposure  to even a lethal  dose of chloroform.



     Intragastric administration  of  250 mg of chloroform/kg body



weight to rats showed gross pathological changes  in both  renal and



hepatic tissues  (Torkelson, et al. 1976).   The  intragastric LD50



for chloroform was 2,000 mg/kg body weight, with most  deaths occur-



ring from 2  to 4 hours.



     Rats, guinea pigs,  and  rabbits  received   repeated exposure  to



chloroform vapor at 85  ppm, 50 ppm,  and 25 ppm (415, 244, and 122



mg/m , respectively) for 7 hours  per  day, 5 days per week  for up  to



203 days.  Dogs were  similarly exposed to  a chloroform concentra-



tion of 122  mg/m  .   The  results of  these  studies are reported  in



Table 1.



     The effects of chloroform on kidney and liver function  in mon-



grel dogs have been reported  (Klaassen  and  Plaa,  1967b).  Male and



female dogs  received intraperitoneal  injections  of chloroform  in



corn oil.   The  24-hour LD5Q was estimated to  be  1,483 mg/kg body



weight using the "up and  down" method  of Browning  (1937).



     Toxic effects by dermal administration have  been demonstrated



in both humans and other mammals.  Torkelson, et al.  (1976) reported
                               C-15

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                             TABLE 1
               Effects of Chloroform Inhalation on
                 Four Laboratory Animal Species*
Animal
Rats :


Guinea Pigs:

Rabbits :


Rats:


Guinea Pigs:

Rabbits :

Dogs:

Concentration
06 X ^
(mg/m )
Male

Female
Male
Female
Male

Female
Male
Female

Male
Female
Male
Female
Male
Female
415

415
415
415
415

415
244
244

244
244
244
244
122
122
Effects
Pneumonia, renal
symptoms, hepatic
degradation
Renal & hepatic
pathology
No effects
Pneumonitis
Pneumoni tis ,
hepatic necrosis
Hepatic, renal
pathology
Symptoms less
severe than re-
ported at 415 mg/m
Less affected than
males
Normal
Normal
Normal
Normal
Normal
Microscopic
changes in kidney
*Source:  Torkelson,  et al.  1976
                              C-16

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on  adverse  effects  in  the rabbit.   One to  two  24-hour applica-



tions,  by  a cotton pad  bandaged  on the shaven belly of rabbits,



produced a  slight hyperemia with moderate necrosis and a  resulting



eschar  formation.  Healing  appeared to  be  delayed on the site and



on  abraded  areas  treated  in the same way.   Single applications as



low as 1,000 mg/kg of body weight  for 24  hours under an impermeable



plastic  cuff  resulted in  degenerative  changes  in  the  kidney tu-



bules.  Chloroform dropped into  the eyes  of rabbits produced slight



injury which required one week  to  heal.



Synergism and/or Antagonism



     In male rats, chloroform has been  demonstrated to be hepato-



toxic.  Experiments have  elucidated the role of microsomal amidopy-



rine N-demethylase activity in  the hepatotoxic  response  (Gopinath



and  Ford,   1975).    Pretreatment  with   phenobarbitone   sodium  or



phenylbutazone,  from 1 hour to  14  days  prior  to single oral doses



of chloroform,  induced this enzyme  and potentiated the hepatotoxic



effects of chloroform, i.e.,  necrotized  cells, up to 1,000 percent



over  control  values.    On  histological  examination,  degenerative



cells  were   also  apparent.    Pretreatment with  sodium  diethyl-



dithiocarbamate  and  carbon  disulfide has  been shown  to protect



against  liver damage,  with no  necrotized  regions apparent histo-



logically.



     Pretreatment with alcohols, barbiturates, and other  chemicals



such as DDT  increased  the  toxic effects  of chloroform, apparently



by  lowering the  threshold  for  its  necrotic  action.   Studies by



Ilett, et al. (1973)  indicate that this  synergistic effect may be



related to enhanced tissue  binding.
                               C-17

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     Kutob and Kutob (1961)  found  that  ethanol pretreatment of mice



increased the  toxic effects of chloroform  on  the  liver.   McLean



(1970)  demonstrated  the  potentiating  effects  of other  agents.



Phenobarbital and DDT increased the liver hydroxylating enzyme ac-



tivity, and  the toxicity of  chloroform  was more than doubled by the



pretreatment with these chemicals as measured by the LD  .



     Animals on high fat or  protein-poor  diets are more susceptible



to hepatotoxicity from  chloroform, whereas  diets high in carbohy-



drates and proteins  have a protective effect (von Oettingen,  1964).



Teratogenicity



     In 1974, Schwetz, et al. demonstrated the effects of repeated



exposures to chloroform  on  rat  embryos  and  fetal  development.



Pregnant Sprague-Dawley rats were  exposed to  airborne chloroform at



147, 489, and 1,466  mg/m  for  7  hours  per day on  days  6  to 15 of



gestation.  Pregnant rats exposed  to  489  mg/m  showed a significant



increased incidence of  fetal abnormalities compared with controls.



There  were   significantly  increased  incidences  of  acaudia  (no



tails}, imperforate anus, subcutaneous  edema, missing ribs, and de-



layed  sternebrae  ossification.   Rats  exposed  to 147  mg/m  showed



significantly  increased incidences of delayed  skull  ossification



and wavy  ribs, but  exhibited no other deleterious effects compared



with controls.



     Thompson, et  al.   (1974)  reports  in a range-finding study on



rats,  oral  doses of  chloroform  (126 mg/kg/day  and greater)   pro-



duced  dose-related  maternal toxicity.   Doses of 316 mg/kg/day and



greater  caused  acute toxic  nephrosis  and hepatitis  and  death of



dams,  as  well as  fetotox icity.   Results of  the Thompson,  et al.
                               C-18

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(1974)  study  in  the  rabbit suggest this species to be more  sensi-



tive  to the  effects of  chloroform,   in  that  oral  doses  of  100



mg/kg/day or  higher  were  toxic  to  both  the dam  and fetus.



     In these teratology  studies,  the occurrence of adverse  clini-



cal effects in the females of both species and of hepatotoxicity in



the  rabbit  indicates that  maximum tolerated  doses  of chloroform



were used.   At levels toxic to the mother,  only mild fetal  toxicity



in the  form of reduced birth weights was observed.  Dose levels  as



high as 126 mg/kg/day in  the rat and 50 mg/kg/day in the  rabbit were



neither embryocidal  nor teratogenic.



     The occurence of fetal anomalies (Schwetz, et al. 1974) following



exposure of  pregnant rats  to chloroform  by  inhalation,  and  the



absence of effects following oral  exposure (Thompson, et al. 1974)



may be  attributed to the difference  in routes of administration.



Blood concentrations and  tissue distribution of chloroform  in ma-



ternal  and fetal  compartments would undoubtedly be affected  by  the



route and  duration  of maternal exposure which differed in the  two



studies, i.e., continuous exposure seven hours daily in  the inhala-



tion study compared  with  one or two short periods of exposure  per



day in  the oral study.



Mutagenicity



     Chloroform,  tested by  the  histidine-revertant mutation  system



employing  Salmonella typhimur imr»  tester  strains,  was  found to  be



negative.   The  other trihalomethanes  formed  by  chlorination  of



drinking water were  positive  in  such  tests  (Simmon, et  al.  1977).
                               C-19

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Carcinogen!city



     Eschenbrenner and Miller (1945)  studied  the effect of repeated



oral doses of chloroform on the induction of hepatomas in mice.  A



graded series of necrotizing and nonnecrotizing doses of chloroform



was administered.  Three-month-old strain A  mice  which  had  an in-



cidence of  spontaneous hepatomas of  less  than one percent  at 16



months were  given intragastric doses  of chloroform  in  olive oil



solutions at  5  ml/kg body weight.  The  chloroform  content  of the



solutions varied  so  that  the  chloroform  doses were  1.6,  0.8, 0.4,



0.2,  or   0.1  ml/kg,  respectively (2,373,  1,187,  593,   297,  148



mg/k'g).



     The  presence  or absence of  liver  necrosis  was determined by



microscopic  examination  of  liver sections  taken 24  hours  after



administration of a  single dose of chloroform.   The livers of ani-



mals receiving doses of 297  and 148 mg/kg  of chloroform showed no



necrosis.   However, with these doses,  necrotic areas were observed



in the kidneys of  males, but not of females.   This  sex difference of



renal necrotic lesions was observed at all concentrations.  No sex



difference  was  observed  for  liver necrosis.    Twenty-four  hours



after a single dose  of  593  mg/kg  or more of  chloroform, there was



extensive necrosis of liver  cells  around  the  central veins.  Thirty



doses were given at four-day intervals  to test for any carcinogenic



effect.  (This was the  schedule  under which a hepatoma incidence of



100  percent  was  obtained  when  carbon  tetrachloride  was   used).



Hepatomas  were  found  only   in  animals  that  received necrotizing



doses of chloroform  (at least 593 mg/kg) and which were killed one



month after  the  last dose.   These were  seen only in  female mice,
                               C-20

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which  could reflect the  lower  tolerance to chloroform  for males,



i.e.,  the  males  might  have died earlier of renal necrosis, before



onset  of malignant changes.   The  authors suggested that  necrosis



was a  prerequisite  to  tumor  induction.



     In  1976,  the National Cancer  Institute  (NCI) released  its Re-



port on Carcinogenesis Bioassay of  Chloroform.   This  study  followed



the protocol that had been developed for testing a series of chemi-



cals by the Carcinogenesis Bioassay Program of  the Division of Can-



cer Cause  and  Prevention.  The  work was  carried out  under contract



with the Hazelton Laboratories  of  America,  Inc.



     A Carcinogenesis bioassay of USP grade chloroform was conduct-



ed using male  Osborne-Mendel rats  and both male and female B6C3F,



mice.  Chloroform was  administered orally (by  gavage)  in corn oil



to 50  animals  of each  sex and at two dose levels 5  times per week



for 78 weeks.  Rats were  started on the  test at 52 days  of age and



killed after 111 weeks.   The  dose  levels  for males were  90 and 180



mg/kg body weight.   Female rats were started at 125  and  250 mg/kg,



reduced to 90 and 180 mg/kg after 22 weeks, with an average  level of



100 and 200 mg/kg for  the study.   A decrease in survival rate and



weight gain was evident for  all treated  groups.  The most signifi-



cant observation (p =  .0016)  was  kidney epithelial  tumors  in male



rats with  incidences of:   0  percent in controls,  8   percent in the



low-dose groups, and 24 percent in  the high-dose  groups  (Table 2).



An increase  in thyroid tumors was  also observed  in  treated female



rats,  but  this finding was  not considered statistically signifi-



cant.
                               C-21

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                                           TABLE 2

                      Statistically  Significant  Tumor  Incidence  in Rats*
                                                               Males
                                         Controls
                                     Colony    Matched       Low Dose           High Dose

Kidney epithelial tumors/animals      0/99      0/19       90 mg/kg 4/50     180  mg/kg  12/50
                                                               (8%)               (24%)

p value                              0.0000    0.0016
*Source:  NCI, 1976
                                            C-22

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     The epithelial tumors varied from circumscribed, well-differ-



entiated tubular-cell adenomas  to  highly pleomorphic, poorly dif-



ferentiated  carcinomas  which had  invaded and metastasized.   The



cells in adenomas were  relatively uniform and polygonal, with abun-



dant eosinophilic cytoplasm.   Nuclei were central or  basal  in loca-



tion, with  minimal atypia and  little increase  in  mitotic index.



Most carcinomas were very large  and  replaced  a considerable portion



of the renal parenchyma.  They were  infiltrated  surrounding normal



tissues  and  were poorly  circumscribed.   These  cells  assumed  the



form of  irregular  sheets,  nests,   and   tubular  arrangements  with



varying  degrees  of  anaplasia  and   increased  nuclear/cytoplasmic



ratio.    The nests of  cells  were often  surrounded  by  a delicate



fibrovascular stroma,  and central necrosis was sometimes present in



the more anaplastic neoplasms.  A papillary  glandular pattern was



rarely observed.



     Mice were started on test at 35 days and killed  after  92 to 93



weeks.   Initial dose levels were 100 and 200 mg/kg for males and 200



and 400  mg/kg  for  female  mice.   These levels were increased after



18 weeks to  150/300  and 250/500 mg/kg,  respectively,  so  that the



average levels were 138  and 277 mg/kg  for male and 238 and 477 mg/kg



for female mice.   Survival rates and weight  gains were comparable



for all groups except high, dose females  which had a  decreased sur-



vival.    Highly  significant  increases (p = ,001)  in  hepatocellular



carcinoma were observed in both  sexes of mice with  incidences of 98



percent and 95 percent  for males and  females at  the  high dose, and



36 and 80 percent  for males and females  at the low dose  (Table 3).



This compares with  six  percent  in  both matched and  colony control
                               C-23

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                                       TABLE 3

                     Hepatocellular Carcinoma Incidence in Mice*
                     Controls
              Colony         Matched            Low Dose                High Dose

Male           5/77           1/18          138 mg/kg 18/50          277  rag/kg  44/45

               (6%)           (6%)               (36%)                    (98%)

Female         l/80a          0/20          238 mg/kg 36/45a         477  mg/kg  39/41

               (1%)           (0%)               (80%)                    (95%)


*Source:  NCI, 1976

aData  used  for  calculation  of  cancer  risk in Criteria  Formulation section  of this
 document.
                                         C-24

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males, zero percent  in matched control females, and one percent  in



colony control  females.   Nodular  hyperplasia of the liver was ob-



served  in  many low dose male mice  that  had not developed hepato-



cellular carcinoma.



     The  incidence of  hepatocellular carcinoma  is significantly



elevated in both  sexes  of  mice.   A high incidence of these tumors



was observed  in all  treated groups, and the difference was deter=



mined to be statistically  significant at the p< 0.001  level.   The



lesions were  observed  in animals which  died  as early  as 54 weeks



following initial exposure.   The  increase in lesion  development ob-



served is due to  the occurrence of  a  specific type  of tumor, hepa-



tocellular carcinoma.   The  tumors  varied  from  those  composed of



well-differentiated hepatocytes with  a relatively uniform arrange-



ment, to those which  were very anaplastic and poorly differentiated



with  numerous mitotic  figures.   Various  types of hepatocellular



carcinomas described in the  literature  were seen,  including those



with an orderly cord-like arrangement of  neoplastic  cells,  those



with a pseudoglandular  pattern resembling adenocarcinoma, and those



composed of sheets of highly anaplastic  cells with  little tendency



to form a  cord or  gland-like arrangement.  The diagnosis of hepato-



cellular carcinoma was based  primarily on histologic character-



istics of  the neoplasm.   Hepatocellular carcinomas were found  to



have metastasized  to  the  lung  in two low-dose males a.id two high-



dose females, and  to the kidney in  a  high-dose  male.



     A search of the literature  has not revealed long-term followup



studies on industrially-exposed  populations.   It is expected  that



there would be a long latency period.  A  survey of plant  workers who
                               C-25

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had been exposed for only a few  years would  not be expected to show



a significant increase in cancer.



     When data  on  chloroform  concentrations became available from



the U.S. EPA's  surveys of  drinking  water,  a correlation was noted



with cancer death rates for all  sites  in  the  survey  (McCabe, 1975).



Fifty  cities,  where  at  least  70  percent  of  the  population  was



served by the water sampled, had chloroform concentrations measured



in 1975 that could  be compared with  cancer mortality in  1969-71.  A



statistically significant correlation was reported  between the age,



sex, and race-adjusted death  rate for  total  cancer and chloroform



levels.



     Epidemiology studies of cancer  frequency for trihalomethanes,



of which chloroform  is a primary chemical species, began to appear



in 1974.  EPA asked a number of  research  groups to evaluate whether



there was  a  relationship between cancer rates and  chloroform  and



other trihalomethanes (THM) in water supplies.  Most of  the EPA re-



quested studies  used indirect evidence of the presence of  THM in



water supplies while two  others  used direct measurements of chloro-



form and other THM.



     This type of study has been extended by Cantor, et al.  (1977)



who looked  at  the  association between each  of 16  cancer  rates in



whites, by sex and  levels of  trihalomethanes separated  into Chloro-



form and nonchloroform components.  Exposure information came from



the National Organics Reconnaissance Survey and  the U.S. EPA  Region



V Survey of 1975.  Seventy-six counties,  in  which more  than  50 per-



cent of the  population was served by the sampled  and assayed water



supply, were  included in the  study.   The  most  consistent  finding
                               C-26

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was an association between bladder cancer mortality  rates  and  tri-

halomethane levels.  The association  was observed in  both  sexes and

showed a gradient of increasing degree of correlation when  counties

were grouped by percentage of the county  population served by the wa-

ter supply.   The  correlations noted  were stronger with the  bromi-

nated trihalomethanes than with  chloroform.

     Hogan, et al. (1977) used approximately the same data  base and

applied various statistical procedures  to the data in order  to  de-

termine the appropriateness of  the statistical model.  The  results

were similar  to previous  studies showing positive correlation  be-

tween  rectal-intestinal  and  bladder cancer  mortality  rates   and

chloroform  levels  in drinking  water,  when a  weighted  regression

analysis was applied.

     Given  the  number  of  existing epidemiology  studies,  the   EPA

asked the  National Research Council  to review  the  studies.    The

National Academy of Sciences (NAS, 1978b) provided such  a review of

10 epidemiology studies,  including  the  ones previously mentioned.

It is useful to quote from their  summary and conclusions:

     The studies  that  the subcommittee   reviewed were divided
     into  two groups:   those  in  which nonspecific measures  of
     exposures to putative carcinogens in water  (e.g., the  use
     of  surface  water  vs.  ground water)  were  examined   and
     those  in  which  water quality was  characterized by mea-
     surements of  trihalomethane  (THM)  concentrations.    The
     subcommittee  gave  greater  weight  to  the  conclusions  of
     the latter  group  of  studies because  crude measures  of
     exposure, which lead to the comparisons of  cancer between
     surface water users  and  ground water  users,  must  be  of
     limited  value.   They do  not permit the  quantitation  of
     exposure  to   contaminants   in water consumed,  which  is
     needed  to  determine  dose-response  relationships between
     THM concentrations and cancer frequencies  and  to estimate
     the effects of  reducing  THM concentrations.
                               C-27

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The conclusions drawn in the second group of studies, in
which many cancer  sites were examined, suggest that high-
er  concentrations  of  THMs  in  drinking  water  may  be
associated with an  increased frequency  of  cancer  of the
bladder.  The results do  not establish causality, and the
quantitative estimates of. increased or decreased risk are
extremely  crude.    The  effects  of  certain potentially
important  confounding  factors,  such as  cigarette  smok-
ing, have not been determined.
                          C-28

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                      CRITERION FORMULATION



Existing Guidelines and Standards



     The Occupational Safety and Health Administration  (OSHA)  limit



for chloroform in work place air is 50 ppm, or 244  mg/m  .  This  is a



"ceiling value"  for  a maximum  10-minute  exposure that at no  time



should be exceeded.  NIOSH recommended  a  criterion of  10 ppm  (48.9



mg/m ) in 1974.  This criterion was applied  to a  time-weighted ex-



posure for  as  high as 10 hours  per  day  and  a  40-hour work week.



Following the National Cancer Institute (NCI) study of chloroform,



NIOSH on June 9,  1976, reduced this allowable  time-weighted average



exposure criterion to 2 ppm (9.8 mg/m  ).



     Based  on  available  health  information,  a safe  level  of  air-



borne exposure to halogenated  agents  could not be  defined.  Since a



safe  level   of  occupational  exposure  to  halogenated anesthetic



agents could  not  be  established by either animal or human invest-



igations, NIOSH  recommended  that airborne  exposure  be limited to



levels no greater than the lowest level detectable using the recom-



mended sampling and analysis  techniques (NIOSH, 1977).  At  the  pre-



sent, chloroform  is not usually used as an  anesthetic; this use is



included in  the criterion and is limited  to  2 ppm or 9.8 mg/m  .



     If  a procedure  that  converts  this air limit to a water  limit



is employed,  the  equivalent  exposure  in  water would  be  34.9  mg/1



(Stokinger  and Woodward,  1958).   In this method, complete absorp-



tion  from   inhalation and ingestion  is assumed.    The inhalation



absorption  may be closer  to  50 percent  and the equivalent  water



exposure would then be 17.4 mg/1.   The occupational limits  apply to



the healthy working-age population, and even  then if exposure  level
                               C-29

-------
is half the limit, comprehensive medical surveillance  is required.



To use  the  occupational limit as a guide  for  the general popula-



tion,  an  application factor of  100  can be used.   Thus,  an equi-



valent level in water would  be 174 jug/1.  It must  be  remembered that



the occupational limit  for  chloroform  is based on the  lowest level



detectable in air using  NIOSH  recommended analytical  techniques and



does not necessarily  represent a level  adequate  to  protect man.



     In general, the  use of inhalation  data assumes  an 8-hour day,



time-weighted  average,  occupational  exposure  in the working place



with workers inhaling the  toxic substance throughout such a period.



Exposures for  the  general population should be considerably less.



Such worker-exposure inhalation standards are inappropriate for the



general population  since  they presume an  exposure  limited  to an



eight-hour day, an age  bracket of the  population that excludes the



very young  and the  very old,  and a  healthy worker  prior  to expo-



sure.  Ingestion data are far superior  to  inhalation data when the



risks associated with the  food and  water of the aquatic environment



are being considered.



     Following  the NCI  study  of  chloroform,- the Food and Drug Ad-



ministration took action to halt  the  use of chloroform  in drug pro-



ducts, cosmetic products, and food contact materials (41 FR  15026,



15029).   The  EPA has issued a notice  of  "rebuttable  presumption"



against continued registration of chloroform-containi .g pesticides



(41 FR 14588).



     The EPA has also proposed an amendment which would add  to  the



National  Interim  Primary  Drinking  Water  Regulations  a section



on  the control  of  organic halogenated chemical  contaminants  in
                               C-30

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drinking water  (43 FR 5756).  The proposed limit for total trihalo-



methanes, which includes  chloroform,  is 100 pg/1.  This  limit  was



set largely on  the basis of technological and economic  feasibility.



Originally  the limit will apply only  to  water  supplies  serving



greater  than  75,000  consumers;  this is intended  to provide an  or-



derly  upgrading of  drinking water  treatment  in  the country.    The



basis and purpose of the regulation  are discussed in a  paper by  the



Office of Drinking Water issued  in January,  1978  (U.S.  EPA,  1978b).



This document contains  a number of  estimates  of cancer risk attri-



butable  to  the  presence of chloroform  in drinking  water.   One of



these, performed by NAS, using a linear  non-threshold extrapolation



from animal data, estimated  that  the  lifetime risk  would fall  be-



tween 1.5 X 10"7  and  17 X  10~7  ug/CHC!3/l of water consumed daily



depending upon  the data set employed.   The  upper  95 percent confi-



dence  estimates  would  range   between  3 X 10~   and   22 X 10~



iig/1/day.



Current Levels  of Exposure



     The National Academy  of Science  (NAS,  1978a)  assembled data



based on human exposure  to  chloroform.   Their  calculations of human



uptake are based on  fluid  intake,  respiratory volume, and  food con-



sumption data for "reference man" as compiled by  the International



Commission  for  Radiological  Protection.   Table  4 from the NAS  re-



port  is  reproduced  to  show  their  estimates  of  chloroform uptake



from  fluids.   Table  5  presents the data  on relative human uptake



from the three  sources.



     According  to the NAS  report  the uptake of chloroform from  the



atmosphere at minimum levels of exposure  is about 10 times  greater
                               C-31

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                                                    TABLE 4

                   Chloroform  Uptake  From  Fluids  (mg/yr)  Assuming  100  Percent Absorption8'
Exposure
Minimum
Concentration
Exposure
(0.0001 mg/1)
Median
Concentration
Exposure
(0.021 mg/1)
Max imuro
Concentration
Exposure
(0.366 mg/1)
                 Fluid
Tap
Water

Other1
Total
Fluid

Tap
Water

Other11
Total
Fluid

Tap
water

Other1
Total
Fluid
Adult
Mln.
Fluid
Intake
0.016
0.012
0.037
3.44
2.45
7.57
60.0
42.7
134
Man
Max.
Fluid
Intake
0.027
0.053
0.088
5.59
11.1
18.4
97.5
194
321

Refer .
Man
Intake
0.005
0.055
0.071
1.15
11.5
14.9
20.1
200
261
Adult
Min.
Fluid
intake
0.016
0.012
0.037
3.44
2.45
7.67
60.0
42.7
134
Woman
Max.
Fluid
Intake
0.027
0.053
0.086
5.59
11.1
18.4
97.5
194
321

Refer.
Man
Intake
0.004
0.040
0.051
0.77
8.43
10.7
13.4
147
187
Child
(5-14 Yr) (10 Yr)
Min. Max. Refer.
Fluid Fluid Man
Intake Intake Intake
0.007
0.020 0.029
0.027
0.036 0.061 0.051
1.53
4.14 6.06
5.75
7.67 12.8 10.7
26.7
72.1 106 100
134 223 187
aCalculated by multiplying the exposure concentration (ug/1) x fluid intake (1/yr)  for minimum and
 maximum Intakes, and dividing by 1000 ng/mg - mg/yr.

 Includes water based drinks, such as tea, coffee, soft drinks, beer, cider,  wine.

*Source:  NAS, 1978a
                                                 C-32

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                                         TABLE 5
                Relative Human Uptake of Carbon Tetrachloride  (CC1.)  and
                Chloroform  (CHC1-J  from Environmental  Sources  (rag/year)*
At Minimum Exposure Levels3

Source
Fluid Intake
Atmosphere
Food Supply
Total
Adult
cci4
0.73
3.60
0.21
4.54
Man
CHC13
0.037
0.41
0.21
0.66
Adult
cci4
0.73
3.30
0.21
4.24
Woman
CHC13
0.037
0.37
0.21
0.62

cci4
0.73
2.40
0.21
3.34
Child
CHC13
0.036
0.27
0.21
0.52
At Typical Exposure Levels

Source
Fluid Intake
Atmosphere
Food Supply
Adult
cci4
1.78
4.80
1.12
Man
CHC13
14.90
5.20
2.17
Adult
CC1.
4
1.28
4.40
1.12
Woman
CHC13
10.70
4.70
2.17

cci4
1.28
3.20
1.12
Child
CHC13
10.70
3.40
2.17
Total
7.70
22.27
6.80
17.57
5.60
16.27
                                           C-33

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                                   TABL3 5 (Continued)
Source
                        Adult Man
               CC1,         CHC1.
                                   At Maximum Exposure  Levels
                                           Adult Woman
Fluid Intake

Atmosphere

Food Supply

Total
               629
811
              CC1.
           CHC1
578
771
                                             Child
                                                                       CC1
                          CHC1.
4.05
618
7.33
321
474
16.4
4.05
567
7.33
321
434
16.4
1.83
405
7. 33
223
310
16.4
414
549
*Source:  NAS , 1978a
     (a)
     (b)
(c)
      Minimum conditions of all variables  assumed:   Minimum exposure-minimum in-
      take for  fluids;  minimum exposure-minimum  absorption for atmosphere;  and
      minimum exposure-minimum intake for food supplies.

      Typical conditions of all variables assumed.  For CC1.:  0.0025 mg/1-refer-
      ence man intake for fluids;  average of  typical minimum and maximum  absorp-
      tion for atmosphere;  and  average exposure and  intake for food supplies.  For
              median exposure-reference  man intake for  fluids;  average of  typical
              and maximum absorption for atmosphere; and  average exposure  and in-
      take for food supplies.
           minimum
           Maximum  conditions  of all  variables  assumed:  maximum  exposure  intake for
           fluids; maximum exposure-maximum absorption for atmosphere; and maximum ex-
           posure-maximum intake for food supplies.
                                          C-34

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 than  from fluids.   At maximum exposure levels,  the  chloroform  up-

 take  from fluids is slightly less  than  that from the  atmosphere.

 At  typical exposure levels, however, the human  uptake  from  fluids

 is  2 to 3 times greater than from the atmosphere, with slight vari-

 ation  by  sex  and age  noted.

     In  its Statement  of Basis and  Purpose  for  an Amendment  to  the

 National  Interim Primary  Drinking  Water Regulations on  Trihalo-

 methanes,  the U.S.  EPA (1978b)  estimated the total  human  exposure

 to chloroform (Table 6).   The estimates have basic assumptions that

 are comparable to those used by  the  NAS  (1978a),  are  based  on newer

 values for chloroform content in  drinking  water  from  NOMS data,  and

 provide estimates for  human  adults  only.

     The  two  exposure estimates,   NAS  (1978a)   and   the  U.S.  EPA

 (1978b) demonstrate that chloroform  intake  from  ingesting  water  is

 likely to  range  from  a modest to predominant  percentage of  total

exposure with a simple minimum, mean and maximum exposure scenario.



                              % total exposure    %  total  exposure
                                 from water           from  water
                                 (U.S. EPA)       	(NAS)	


     Minimum Exposure                23%                  6%
     Mean Exposure                   69%                 67%

     Maximum Exposure                61%                 40%


Basis and Derivation of Criteria

     Chloroform  has several  adverse effects  on the human  body.

 Safe levels of chloroform in water  necessary to  avoid some  of these

effects would  be difficult  to establish  because adequate studies

 have not  been conducted.   The most  serious effect  to consider  is
                               C-35

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                                TABLE 6
            Uptake of Chloroform  for  the Adult Human
                   from Air, Water,  and Food*
Source
Atmosphere
Water
Food Supply
Total
Atmosphere
Water
Food Supply
Total
Atmosphere
Water
Food Supply
Total
Adult
mg/yr
Maximum Conditions
204
343
16
563
Minimum Conditions
0.41
0.73
2.00
3.14
Mean Conditions
20.0
64.0
9.00
93
Percent
uptake
36
61
3
100.00
13
23
64
100.00
22
69
10
101.00
*Source: U.S. EPA, 1978b
                              C-36

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the  cancer-causing  potential of  the  chemical.   Current  knowledge
leads  to  the conclusion  that  carcinogenesis  is  a non-threshold,
nonreversible process.  The non-threshold concept  implies  that many
tumors will be produced at high doses, but any dose, no matter how
small, will  have the  probability of causing  cancer.   Even small
carcinogenic  risks  have  a serious impact on society  when the ex-
posed  population  is large,  because it is likely that some cancers
will be caused  by chloroform.   The  nonreversible  concept implies
that once  the tumor growth  process  has  started,  growth will con-
tinue  and  may metastasize  and involve  other  organs  until  death
ensues.
     Chloroform has  been  shown to induce cancer in two species of
experimental  animals.   This conclusion  is neither  confirmed  nor
denied by  the  results  of numerous epidemiology studies now avail-
able, although from a public health point of view,  a suspicion of a
qualitative weight of evidence for confirmation probably exists.
     The available  information on  total  human  exposure to chloro-
form from air, water, and food  sources suggests  that drinking water
contributes from 6 to 69  percent of the total exposure.  Studies in
which water quality was  characterized by measurements of THM con-
centrations suggest that higher  trihalomethanes  (TKM) concentra-
tions  in drinking water  may be associated  with an increased fre-
quency of  cancer  of  the  bladder.    The  results do  not establish
causality,  and  the  estimates  of  increased or  decreased  risk are
extremely crude.
     It is therefore proposed  that the total risk  for carcinogenic
response be allocated  to  the ambient water exposure conditions of
                               C-37

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ingesting 2  liters/day  of  water  and  consuming 6.5 grams of poten-



tially contaminated fish products.



     Under  the  Consent  Decree  in  NRDC v. Train,  criteria are to



state  "recommended  maximum permissible  concentrations  (including



where appropriate, zero) consistent with the protection of aquatic



organisms, human health, and recreational activities."  Chloroform



is  suspected  of being  a human  carcinogen.   Because there  is no



recognized  safe  concentration  for a human  carcinogen,  the recom-



mended concentration of chloroform in water for maximum protection



of human health is zero.



     Because attaining a zero  concentration level  may be infeasible



in some cases, and in order to assist the Agency and states in the



possible future development of water quality regulations,  the con-



centrations  of chloroform  corresponding  to   several  incremental



lifetime cancer  risk  levels have  been estimated.   A  cancer risk



level provides  an  estimate  of  the additional  incidence  of cancer



that may be expected in  nn  exposed  population.  A  risk of 10   , for



example, indicates a probability of  one  additional case of cancer



for every 100,000 people exposed; a risk of 10~  indicates one  addi-



tional  case  of cancer  for  every  million  people  exposed,  and so



forth.



     In  the  Federal  Register  notice of  availability of draft am-



bient  water  quality criteria,  EPA stated that  it is considering


                                                      — 5    — fi
setting criteria at an  interim  target  risk level  of  10   ,10   , or



10~  , as shown  in  the following  table.
                               C-38

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   Exposure Assumptions                  Risk Levels
	(per day)	   	and Corresponding Criteria  (1)

                                1£"7          _10"6            1£~5

2 liters of drinking         0.019  ug/1     0.19 ug/1      1.90 pg/l
water and consumption
of 6.5 grams of
fish and shellfish  (2)

Consumption of fish          1.57   ug/i     15.7 ug/1      157 ug/i
and shellfish only.


(1)  Calculated by applying a linearized multistage model, as dis-

     cussed  in  the  Human Health  Methodology  Appendices  to the

     October  1980  Federal  Register  notice  which announced the

     availability  of  this document,  to the animal  bioassay  data

     presented in Appendix I and in Table 3.  Since the extrapola-

     tion model  is linear at  low  doses,  the  additional  lifetime

     risk  is  directly  proportional  to  the  water  concentration.

     Therefore,  water  concentrations  corresponding to  other  risk

     levels can be  derived  by multiplying  or dividing  one of the

     risk levels  and  corresponding  water concentrations  shown  in

     the table by factors such as 10,  100,  1,000, and so forth.

(2)   Approximately  1  percent of  the  chloroform  exposure results

     from the consumption of aquatic  organisms which  exhibit  an

     average bioconcentration potential of  3.75-fold.   The remain-

     ing 99 percent  of chloroform  exposure results  from  drinking

     water.

     Concentration levels were derived by assuming a lifetime expo-

sure to  various  amounts of chloroform:   (1)  occurring from  the con-

sumption of both  drinking water and  aquatic  life  grown in waters

containing the corresponding chloroform concentrations; and (2) oc-

curring solely from consumption of aquatic  life  grown  in  the waters
                              C-39

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containing the  corresponding  chloroform concentrations.   Although
total exposure information for chloroform  is discussed and an esti-
mate  of  the  contributions  from  other  sources of  exposure  can be
made, these  data  will  not be  factored  into  ambient water quality
criteria  formulation  until additional  analysis can  be  made.   The
criteria presented, therefore, assume  an incremental  risk from amb-
ient water exposure only.
                               C-40

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                               C-50

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                            APPENDIX I
              Derivation of Criterion for Chloroform


     The NCI  (1976) bioassay with female mice given a time-weighted
average dose  of  chloroform at 238  or  477  mg/kg by stomach  tube  5
times per week for 78  weeks is  used  to derive the water quality cri-
terion.   The treatment  induced  hepatocellular  carcinomas   in  the
tested animals and controls as outlined in the table below.   Assum-
ing that the fish bioaccumulation factor is 3.75,  the  parameters of
the extrapolation model are:


         Dose                         Incidence
      (mg/kg/day)             (no. responding/no,  tested)
           0                            0/20
    238 x 5/7 = 170                     36/45
    477 x 5/7 = 341                     39/41
     le = 546 days            w = 0.030 kg
     Le = 644 days            R = 3.75 I/kg
     L  = 644 days

     With  these  parameters  the  carcinogenic  potency  for  humans,
q *, is 0.18272  (mg/kg/day   ).   The result is that the water  con-
centration should be less than 1.90  ug/1 in order to  keep  the  indi-
vidual lifetime risk below 10~ .
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