Toxicological
                        Profile
                        for
CHLOROFORM
                                             o
Agency for Toxic Substances and Disease Registry
U.S. Public Health Service
                                             0.
                                             c'
                                             3

-------
                                                   ATSDR/TP-88/09
           TOXICOLOCICAL PROFILE FOR
                   CHLOROFORM
            Date Published — January 1989
                    Prepared by:

             Syracuse Research Corporation
            Under Contract No. 68-C8-0004

                        for

Agency for Toxic Substances and Disease Registry (ATSDR)
              U.S. Public Health Service

                 in collaboration with

      U.S. Environmental Protection Agency (EPA)
       Technical editing/document preparation by:

            Oak Ridge National Laboratory
                       under
     DOE Interagency Agreement No. 1857-B026-A1

-------
                          DISCLAIMER

Mention of company name or product does not constitute endorsement by
the Agency for Toxic Substances and Disease Registry.

-------
                                FOREWORD

     The Superfund Amendments and Reauthorization Act of 1986 (Public
 Law  99-499) extended and amended the Comprehensive Environmental
 Response, Compensation, and Liability Act of 1980 (CERCLA or Superfund)
 This public law (also known as SARA) directed the Agency for Toxic
 Substances and Disease Registry (ATSDR) to prepare toxicological
 profiles for hazardous substances which are most commonly found at
 facilities on the CERCLA National Priorities List and which pose the
 most significant potential threat to human health, as determined by
 ATSDR and the Environmental Protection Agency (EPA). The list of the 100
 most significant hazardous substances was published in the Federal
 Register on April 17, 1987.

     Section 110 (3) of SARA directs the Administrator of ATSDR to
 prepare a toxicological profile for each substance on the list. Each
 profile must include the following content:

     "(A)  An examination, summary, and interpretation of available
     toxicological information and epidemiologic evaluations on a
     hazardous substance in order to ascertain the levels of significant
     human exposure for the substance and the associated acute,
     subacute, and chronic health effects.

     (B)  A determination of whether adequate information on the health
     effects of each substance is available or in the process of
     development to determine levels of exposure which present a
     significant risk to human health of acute, subacute, and chronic
     health effects.

     (C)  Where appropriate, an identification of toxicological testing
     needed to identify the types or levels of exposure that may present
     significant risk of adverse health effects in humans."

     This toxicological profile is prepared in accordance with
guidelines developed by ATSDR and EPA. The guidelines were published in
the Federal Register on April 17, 1987. Each profile will be revised and
republished as necessary, but no less often than every three years, as
required by SARA.

     The ATSDR toxicological profile is intended to characterize
succinctly the toxicological and health effects information for the
hazardous substance being described. Each profile identifies and reviews
the key literature that describes a hazardous substance's toxicological
properties.  Other literature is presented but described in less detail
than the key studies. The profile is not intended to be an exhaustive
document;  however, more comprehensive sources of specialty information
are referenced.
                                                                      111

-------
Foreword

     Each toxicological profile begins with a public health statement.
which describes in nontechnical language a substance's relevant
toxicological properties. Following the statement is material that
presents levels of significant human exposure and, where known,
significant health effects. The adequacy of information to determine a
substance's health effects is described in a health effects summary.
Research gaps in toxicologic and health effects information are
described in the profile. Research gaps that are of significance to
protection of public health will be identified by ATSDR, the National
Toxicology Program of the Public Health Service, and EPA. The focus of
the profiles is on health and toxicological information; therefore, we
have included this information in the front of the document.
     The principal audiences for the toxicological profiles are health
professionals at the federal, state, and local levels, interested
private sector organizations and groups, and members of the public. We
plan to revise these documents in response to public comments and as
additional data become available; therefore, we encourage comment that
will make the toxicological profile series of the greatest use.

     This profile reflects our assessment of all relevant toxicological
testing and information that has been peer reviewed. It has been
reviewed by scientists from ATSDR, EPA, the Centers for Disease Control,
and the National Toxicology Program. It has also been reviewed by a
panel of nongovernment peer reviewers and was made available for public
review. Final responsibility for the contents and views expressed in
this toxicological profile resides with ATSDR.
                                    James 0. Mason, H.D., Dr. P.H.
                                    Assistant Surgeon General
                                    Administrator, ATSDR
iv

-------
                                CONTENTS

FOREWORD 	
LIST OF FIGURES 	    ix

LIST OF TABLES 	    xt

 1.   PUBLIC HEALTH STATEMENT  	    1
     1.1  WHAT IS  CHLOROFORM?  	    L
     1.2  HOW MIGHT I  BE  EXPOSED TO CHLOROFORM?  	    1
     1.3  HOW DOES CHLOROFORM  GET  INTO MY  BODY?  	    2
     1.4  HOW CAN  CHLOROFORM AFFECT MY HEALTH?  	    2
     1.5  IS THERE A MEDICAL TEST  TO DETERMINE  IF I  HAVE  BEEN
          EXPOSED  TO CHLOROFORM? 	    3
     1.6  WHAT LEVELS  OF  EXPOSURE  HAVE RESULTED  IN HARMFUL
          HEALTH EFFECTS? 	    3
     1.7  WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT
          MADE TO  PROTECT HUMAN  HEALTH?  	    7
 2.   HEALTH EFFECTS SUMMARY  	    9
     2.1  INTRODUCTION 	    9
     2.2  LEVELS OF SIGNIFICANT  EXPOSURE 	     10
          2.2.1 Key Studies and Graphical Presentations  	    10
                2.2.1.1   Inhalation 	    LO
                2.2.1.2   Oral 	    19
                2.2.1.3   Dermal	    23
          2.2.2 Biological Monitoring as  a Measure  of
                Exposure and  Effects 	    23
          2.2.3 Environmental Levels as Indicators  of
                Exposure and  Effects 	    25
                2.2.3.1   Levels found in  the environment 	    25
                2.2.3.2   Human  exposure potential 	    26
     2. 3  ADEQUACY OF  DATABASE 	    26
         2.3.1 Introduction  	    26
         2.3.2 Health Effect End Points  	    27
                2.3.2.1   Introduction and graphic summary 	    27
                2.3.2.2   Descriptions of  highlights of graphs  ....    27
                2.3.2.3   Summary  of relevant ongoing research  ....    30
         2.3.3 Other Information Needed  for Human
                Health Assessment 	    31
                2.3.3.1   Pharmacokinetics and mechanisms
                          of action 	    31
                2.3.3.2   Monitoring of human biological  samples  ..    31
                2.3.3.3   Environmental considerations  	    32

 3.   CHEMICAL AND  PHYSICAL INFORMATION 	    33
     3.1  CHEMICAL IDENTITY 	    33
     3.2  PHYSICAL AND CHEMICAL  PROPERTIES 	    33

-------
 Concents

  4.   TOXICOLOGICAL DATA 	            37
      4.1  OVERVIEW	       37
      4.2  TOXICOKINETICS 	'.'.'."   33
           4.2.1  Absorption 	   33
                  4.2.1.1  Inhalation 	   38
                  4.2.1.2  Oral  	'.   39
                  4.2.1.3  Dermal  	   39
           4.2.2  Distribution 	   40
                  4.2.2.1  Inhalation 	   40
                  4.2.2.2  Oral  	   41
                  4.2.2.3  Dermal  	   41
           4.2.3  Metabolism 	   41
                  4.2.3.1  Inhalation 	   41
                  4.2.3.2  Oral  	   41
                  4.2.3.3  Dermal  	   44
           4.2.4  Excretion	   44
                  4.2.4.1  Inhalation 	   44
                  4.2.4.2  Oral  	   44
                  4.2.4.3  Dermal  	      45
      4.3  TOXICITY 	   45
           4.3.1  Lethality and  Decreased Longevity  	   45
                  4.3.1.1  Inhalation 	   45
                  4.3.1.2  Oral  	   45
                  4.3.1.3  Dermal  	   46
           4.3.2  Systemic/Target  Organ Toxicity  	   46
                  4.3.2.1  Liver effects 	   46
                  4.3.2.2  Kidney  effects 	   51
                  4.3.2.3  CNS effects 	   54
           4.3.3  Developmental  Toxicity 	   55
                  4.3.3.1  Inhalation 	          55
                  4.3.3.2  Oral  	   56
                  4.3.3.3  Dermal  	   57
                  4.3.3.4  General discussion  	   57
           4.3.4  Reproductive Toxicity 	   57
                  4.3.4.1  Inhalation 	   57
                  4.3.4.2  Oral  	   58
                  4.3.4.3  Dermal  	   58
                  4.3.4.4  General discussion  	   58
           4.3.5  Genotoxicity  	   58
                  4.3.5.1  Human	   58
                  4.3.5.2  Nonhuman  	   58
                  4.3.5.3  General discussion  	   58
           4.3.6  Carcinogenic ley  	'  61
                  4.3.6.1  Inhalation 	   61
                  4.3.6.2  Oral  	   61
                  4.3.6.3  Dermal	   64
                  4.3.6.4  General discussion  	   64
     4.4   INTERACTIONS WITH OTHER CHEMICALS 	   68
vi

-------
                                                                Concents

 5.  MANUFACTURE, IMPORT, USE, AND DISPOSAL	   71
     5.1  OVERVIEW	   71
     5.2  PRODUCTION 	   71
     5.3  IMPORT 	   71
     5.4  USES  	   71
     5.5  DISPOSAL	   72
 6.  ENVIRONMENTAL FATE  	   73
     6.1  OVERVIEW 	   73
     6.2  RELEASES TO THE ENVIRONMENT 	   73
     6.3  ENVIRONMENTAL FATE  	   73
          6.3.1  Air 	   73
          6.3.2  Water 	   75
          6.3.3  Soil 	   76
 7.  POTENTIAL FOR HUMAN EXPOSURE 	   77
     7.1  OVERVIEW 	   77
     7.2  LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT  	   77
          7.2.1  Air 	   77
          7.2.2  Water 	   78
          7.2.3  Soil 	   78
          7.2.4  Other 	   78
     7.3  OCCUPATIONAL EXPOSURES 	   79
     7.4  POPULATIONS AT HIGH RISK 	   79
 8.  ANALYTICAL METHODS  	   81
     8.1  ENVIRONMENTAL MEDIA 	   81
     8.2  BIOMEDICAL SAMPLES  	   81

 9.  REGULATORY AND ADVISORY STATUS  	   85
     9.1  INTERNATIONAL	   85
     9.2  NATIONAL	   85
          9.2.1  Regulations  	   85
          9.2.2  Advisory Guidance 	   86
                 9.2.2.1  Air 	   86
          9.2.3  Data Analysis  	   87
                 9.2.3.1  Reference  dose  	   87
                 9.2.3.2  Carcinogenic potency  	   87
     9.3  STATE 	   87

10.  REFERENCES 	   89

11.  GLOSSARY 	   Ill

APPENDIX:  PEER REVIEW	   115
                                                                      vil

-------
                            LIST OF FIGURES
1.1  Health effects from breathing chloroform 	    4
1.2  Health effects from ingesting chloroform 	    5
1.3  Health effects from skin contact with chloroform 	    6
2.1  Effects of chloroform-- inhalation exposure 	   11
2.2  Effects of chloroform--oral exposure 	   12
2.3  Effects of chloroform--dermal exposure 	   13
2.4  Levels of significant exposure for chloroform-- inhalation ....   14
2.5  Levels of significant exposure for chloroform--oral 	   IS
2.6  Levels of significant exposure for chloroform--dermal 	   16
2.7  Availability of information on health effects of chloroform
     (human data) 	   28
2.8  Availability of information on health effects of chloroform
     (animal data) 	   29
4.1  Metabolic pathways of chloroform biotransformation 	   42
                                                                       ix

-------
                             LIST OF TABLES
2.1  Relationship of chloroform concentration in inspired air
     and blood to anesthesia 	   24
3.1  Chemical identity of chloroform 	   34
3.2  Physical and chemical properties of chloroform 	   35
4.1  Genotoxicity of chloroform in vitro 	   59
4 2  Genotoxicity of chloroform in vivo 	   60
4.3  Oral carcinogenicity studies of chloroform 	   65
6.1  Sources of chloroform released to the environment 	   74
8.1  Analytical methods for chloroform 	   82
                                                                       XI

-------
                      1.   PUBLIC HEALTH  STATEMENT

1.1  WHAT IS CHLOROFORM?
     Chloroform is a colorless  or water-white  liquid with  a pleasant
nonirritating odor.  Although it is both  a man-made  and naturally
occurring compound,  human activity is  responsible for  most of  the
chloroform found in the environment. Host of the chloroform manufactured
in the United States (93%) is used to  make fluorocarbon-22.
Fluorocarbon-22 is used to make fluoropolymers and  as  a cooling fluid in
air conditioners.  The remaining 7% of  the chloroform produced  in the
United States is either exported to  other countries, used  in the
manufacture of pesticides or dyes, or  used in  various  products including
fire-extinguishers,  dry cleaning spot  removers, and various solvents.

1.2  HOW MIGHT I BE EXPOSED TO  CHLOROFORM?
     The general population may be exposed to  chloroform by breathing
air and ingesting drinking water, beverages, and  foods contaminated with
chloroform. In addition,  skin contact  may occur during the use of
various consumer products containing this compound  or  from exposure to
chlorinated waters (i.e., bath  water,  swimming pool water).

     The primary sources of chloroform release to  the  environment are
pulp and paper mills, pharmaceutical manufacturing  plants, chemical
manufacturing plants, chlorinated wastewater from sewage treatment
plants, and chlorinated drinking water (water  is  chlorinated for
disinfection purposes). Minor sources  of chloroform release  include,  but
are not limited to,  automobile  exhaust gas, use of  chloroform as a
pesticide, burning of tobacco products treated with chlorinated
pesticides, evaporation during  shipping and transport of chloroform,
decomposition of trichloroethylene  (a  man-made product used primarily as
a solvent), evaporation from chlorinated tap water during showering,
evaporation from chlorinated swimming  pool water,  biological production
of chloroform from marine algae,  reaction of chlorinated pollutants with
decayed vegetation,  and burning of plastics. Most of the chloroform
released to the environment eventually enters  the atmosphere,  while much
smaller amounts enter groundwater as the result of  filtration through
soil. Once in the atmosphere, chloroform may be transported long
distances before it finally decomposes. Chloroform  present in soil may
come from improper land disposal of waste material  containing chloroform
or other chlorine-containing compounds that are broken down to form
chloroform.

     People who work in businesses or industries where chloroform  is
found may be exposed to greater amounts of  this compound  than are
members of the general population.  Chloroform is found in a wide variety
of occupational settings as a result of its direct  use in manufacturing

-------
 2   Section 1

 processes,  its  use  as  a  solvent for many different materials, and its
 formation during various chlorination processes.

      Occupational settings  in which chloroform exposure may occur
 include:

    •  Chloroform manufacturing plants

    •  Fluorocarbon-22 manufacturing plants

    •  Ethylene dichloride manufacturing plants

    •  Internal combustion engine industries

    •  Pesticide  manufacturing plants

    •  Pulp and paper mills

    •  Food processing industries

    •  Paint  stores (as  a  result of using chloroform-containing solvents
      for  lacquers,  gums,  greases, waxes, adhesives, oils, and rubber)

 1.3   HOW  DOES CHLOROFORM GET INTO MY BODY?

      Chloroform can enter the body by breathing air, eating food, or
 drinking  water  that contains chloroform. Chloroform readily penetrates
 the skin; therefore, chloroform may also enter the body by bathing or
 showering in water  containing chloroform. Foods such as seafood, dairy
 products, meat,  vegetables, bread, and beverages may contain small but
 measurable  amounts  of  chloroform. Drinking-water supplies containing
 organic contaminants may contain chloroform as a by-product of
 chlorination of the water supply for disinfection purposes.

 1.4   HOV  CAR CHLOROFORM  AFFECT MY HEALTH?

      Chloroform affects  the central nervous system, liver, and kidneys.
 It was used as  a surgical anesthetic for many years before its harmful
 effects on  the  liver and kidneys were recognized. Short-term exposure to
high  concentrations of chloroform in the air causes tiredness,
 dizziness,  and  headache.  Longer-term exposure to high levels of
 chloroform  in the air, or in food and drinking water, can affect liver
 and kidney  function. Toxic effects may include jaundice and burning
urination.  High doses  of chloroform have also been found to cause liver
 and kidney  cancer in experimental animals. The risks of cancer,  if any,
 from  low-level  exposures to chloroform in drinking water as a result of
chlorination, however, are far outweighed by the benefits of
chlorination in terms  of greatly decreased incidence of waterborne
diseases, themselves a potential public health threat and a previous
major contributor to sickness and death.

-------
                                             Public Health Statement   3

1.5  IS THERE A MEDICAL TEST TO DETERMINE IF I HAVE BEEN
     EXPOSED TO CHLOROFORM?

     Although chloroform can be detected in blood, urine, and body
tissues, the methods are not very reliable because chloroform is rapidly
eliminated from the body. In addition, the presence of chloroform in
these tissues may result from the biological breakdown of other
chlorine-containing compounds; therefore, an elevated level of
chloroform in the tissues may reflect exposure to the other compounds
rather than to chloroform itself. Measurements of blood for levels of
liver enzymes can indicate if the liver has been damaged but do not
specifically indicate if chloroform exposure occurred.

1.6  WHAT LEVELS OF EXPOSURE HAVE RESULTED IN HARMFUL HEALTH EFFECTS?
     The graphs on the following pages show the relationship between
exposure to chloroform and known health effects. In health effects from
breathing chloroform (Fig. 1.1), exposure is measured in parts of
chloroform per million parts of air (ppm). In Figs. 1.2 and 1.3, the
same relationship is represented for the known health effects from
ingesting chloroform or skin contact with chloroform. Exposures are
measured in milligrams of chloroform per kilogram of body weight per
day.

     The first column on these graphs, labeled "short term," refers to
known health effects in laboratory animals and humans from exposure to
chloroform for 2 weeks or less. The column labeled "long term" refers to
chloroform exposures of longer than 2 weeks. In all graphs, effects in
animals are shown on the left side and effects in humans on the right
side. The levels marked on the graphs as anticipated to be associated
with minimal risk for humans are based on information from animal
studies that are currently available; therefore, some uncertainty still
exists. From available data in animals, the Environmental Protection
Agency (EPA) has estimated that exposure to 1 microgram of chloroform
per cubic meter of air for a lifetime would result in 0.23 additional
cases of cancer in a population of 10,000 people and 230 additional
cases of cancer in a population of 10,000,000 people. This is the same
as saying that exposure to 1 part of chloroform in a billion parts  of
air (1 ppb) for a lifetime would result in 11 additional cases of cancer
in a population of 10,000 people and 11,000 cases of cancer in a
population of 10,000,000 people. Exposure to drinking water containing 1
milligram of chloroform per liter of water for a lifetime would result
in 1.7 additional cases of cancer in a population of 10,000 people  and
1700 additional cases of cancer in a population of 10,000,000 people. It
should be noted that these risk values are plausible upper-limit
estimates.  Actual risk levels are unlikely to be higher  and may be
lower.

-------
     Section 1
       SHORT-TERM EXPOSURE
  (LESS THAN OR EQUAL TO 14 DAYS)
                           LONG-TERM EXPOSURE
                          (GREATER THAN 14 DAYS)
EFFECTS
IN
ANIMALS
CONC. IN
AIR
(ppm)
EFFECTS
IN
HUMANS
EFFECTS
IN
ANIMALS
CONC. IN
AIR
(ppm)
EFFECTS
IN
HUMANS
              20,000
                       ANESTHESIA
               1500
 DEATH•
               1000
                       DIZZINESS.
                       VERTIGO
                                   LIVER DAMAGE-
               500
LIVER DAMAGE.
EFFECTS ON  •
THE UNBORN
 ODOR
'THRESHOLD
                              100


                              90


                              8)


                              70


                              60


                              50
                                                   .20
                                                   10
                                                          TIREDNESS.
                                                        > DEPRESSION.
                                                          BURNING URINATION
                             0.25.


                              0
                                                           LIVER EFFECTS
                                                           MINIMAL RISK FOR
                                                          •EFFECTS OTHER THAN
                                                           CANCER
                  Fig. 1.1. Heahfc effects tnm breatfctaf cfclonfi

-------
                                            Public Health Statement   5
    SHORT-TERM EXPOSURE
(LESS THAN OR EQUAL TO 14 DAYS)
 LONG-TERM EXPOSURE
(GREATER THAN 14 DAYS)
EFFECTS EFFECTS EFFECTS EFFECTS
IN DOSE IN IN DOSE IN
ANIMALS (mg/kg/day) HUMANS ANIMALS (mg/kg/day) HUMANS
2(
nCATU
1(
9
8
7
ft
(
LIVER AND
KIDNEY < <
DAMAGE
2
^2
1
(


)0 DECREASED I 100
I LONGEVITY—^ I
10 ^90
3 8
3 ri
3 6
0 5
LIVER AND
3 KIDNEY < 4
DAMAGE
0 3
L
o va
) i
•
1 0.
(
)
3
0
)
3
3
LIVER AND KIDNEY
DAMAGE
)
)
)3 	 MINIMAL RISK FOR
EFFECTS OTHER THAN
CANCER
)
f

-------
  Section 1
    SHORT-TERM EXPOSURE
(LESS THAN OR EQUAL TO 14 DAYS)
 LONG-TERM EXPOSURE
(GREATER THAN 14 DAYS)
EFFECTS
IN
ANIMALS
KIDNEY —
EFFECTS








EFFECTS EFFECTS EFFECTS
DOSE IN IN IN
(mg/kg/day) HUMANS ANIMALS HUMANS
	 11
9
8
7
e
5
4
3
2
1
r
)0 QUANTITATIVE QUANTITATIVE
DATA WERE NOT DATA WERE NOT
AVAILABLE AVAILABLE
9
9
9
0
3
9
9
3
9
I
QUANTITATIVE
DATA WERE NOT
AVAILABLE








               Fig. 1J. Health effects tnm skim caatoct with cUorofonk

-------
                                             Public Health Seacement   7

1.7  WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT
     MADE TO PROTECT HUMAN HEALTH?

     The government has made recommendations to limit exposure of
workers to chloroform in the workplace and exposure of the general
public to chloroform in drinking water.  The National Institute for
Occupational Safety and Health (NIOSH) recommended an occupational
exposure limit of 2 parts chloroform per million parts of air averaged
over an 8-hour workday, 40-hour workweek. The Occupational Safety and
Health Administration (OSHA) has a legally enforcible ceiling limit of
50 parts-per-million chloroform in the work atmosphere, which is not co
be exceeded at any time.

     EPA has promulgated a drinking water maximum contaminant level for
total trihalomethanes (compounds similar to and including chloroform) of
100 parts per billion parts of water as a technically and economically
feasible level for municipal water supplies serving 10,000 or more
individuals.

-------
                       2.   HEALTH EFFECTS  SUMMARY
2.1  INTRODUCTION
     This section summarizes and graphs  data on the health effects
concerning exposure to chloroform.  The purpose of this  section is to
present levels of significant exposure for chloroform based on key
toxicological studies, epidemiological investigations,  and environmental
exposure data. The information presented in this section is critically
evaluated and discussed in Sect.  4,  Toxicological Data,  and Sect. 7,
Potential for Human Exposure.

     This Health Effects Summary section comprises two  major parts.
Levels of Significant Exposure (Sect.  2.2) presents brief narratives  and
graphics for key studies in a manner that provides public health
officials, physicians, and other interested individuals and groups  with
(1) an overall perspective of the toxicology of chloroform and (2)  a
summarized depiction of significant exposure levels associated with
various adverse health effects. This section also includes information
on the levels of chloroform that have been monitored in human fluids  and
tissues and information about levels of  chloroform found in
environmental media and their association with human exposures.

     The significance of the exposure levels shown on the graphs may
differ depending on the user's perspective. For example, physicians
concerned with the interpretation of overt clinical findings in exposed
persons or with the identification of persons with the potential to
develop such disease may be interested in levels of exposure associated
with frank effects (Frank Effect Level,  FEL). Public health officials
and project managers concerned with response actions at Superfund sites
may want information on levels of exposure associated with more subtle
effects in humans or animals (Lowest-Observed-Adverse-Effect Level,
LOAEL) or exposure levels below which no adverse effects  (No-Observed-
Adverse-Effect Level. NOAEL) have been observed. Estimates of  levels
posing minimal risk to humans (Minimal Risk Levels) are of interest to
health professionals and citizens alike.

     Adequacy of Database (Sect. 2.3) highlights the availability of key
studies on exposure to chloroform in the scientific literature and
displays these data in three-dimensional graphs consistent with the
format in Sect. 2.2. The purpose of this section is to  suggest where
there might be insufficient information to establish levels of
significant human exposure. These areas will be considered by  the Agency
for Toxic Substances and Disease Registry  (ATSDR),  EPA, and  the National
Toxicology Program (NTP) of the U.S. Public Health Service  in order  to
develop a research agenda for chloroform.

-------
 10   Section 2

 2.2  LEVELS OF SIGNIFICANT EXPOSURE

      To help public health professionals address the needs of persons
 living or working near hazardous waste sites, the toxicology data
 summarized in this section are organized first by route of exposure--
 inhalation, ingestion,  and dermal--and then by toxicological end points
 that are categorized into  six general areas--lethality, systemic/target
 organ toxicity,  developmental toxicity, reproductive toxicity, genetic
 toxicity,  and carcinogenicity. The data are discussed in terms of three
 exposure periods--acute, intermediate, and chronic.

      Two kinds of graphs are used to depict the data. The first type is
 a "thermometer"  graph.  It  provides a graphical summary of the human and
 animal toxicological end points (and levels of exposure) for each
 exposure route for which data are available. The ordering of effects
 does not reflect the exposure duration or species of animal tested. The
 second kind of graph shows Levels of Significant Exposure (LSE) for each
 route and exposure duration. The points on the graph showing NOAELs and
 LOAELs reflect the actual  doses (levels of exposure) used in the key
 studies.  No adjustments for exposure duration or intermittent exposure
 protocol were made.

      Adjustments reflecting the uncertainty of extrapolating animal data
 to  man,  intraspecies variations, and differences between experimental vs
 actual human exposure conditions were considered when estimates of
 levels posing minimal risk to human health were made for noncancer end
 points.  These minimal risk levels were derived for the most sensitive
 noncancer  end point for each exposure duration by applying uncertainty
 factors. These levels are  shown on the graphs as a broken line starting
 from the actual  dose (level of exposure) and ending with a concave-
 curved line at its terminus. Although methods have been established to
 derive these minimal risk  levels (Barnes et al. 1987), shortcomings
 exist in  the techniques that reduce the confidence in the projected
 estimates.  Also  shown on the graphs under the cancer end point are low-
 level risks (lO'4 to 10'7)  reported by EPA. In addition, the actual dose
 (level of  exposure)  associated with the tumor incidence is plotted.

 2.2.1 Key Studies and  Graphical Presentations

      Dose-response-duration data for the toxicity and carinogenicity of
 chloroform are displayed in two types of graphs. These data are derived
 from  the key studies described in the following sections. The
 "thermometer"  graphs In Figs. 2.1 through 2.3 plot exposure levels vs
 NOAELs and LOAELs for various effects and durations of inhalation and
 oral  exposures,  respectively. The graphs of levels of significant
 exposure in Figs.  2.4 through 2.6 plot end point-specific NOAELs and
 LOAELs, and minimal  levels  of risk for acute (314 days), intermediate
 (15-364 days), and chronic  (fe365 days) durations for inhalation, oral,
 and dermal  exposures, respectively.

 2.2.1.1  Inhalation

      Lethality and decreased longevity.  Data regarding inhalation
exposure levels  that produce death in humans were not available. An
 inhalation  LCso  of 10,000 ppm for 4 h for rats was reported by  Lundberg
et al.  (1986). Deringer et  al. (1953) found that an inhalation  exposure

-------
                                                            Health  Effects  Summary    11
  ANIMALS
100000  I-
 10000
  1000
   100
    10
                                                                    HUMANS
                                                                     (PP«n>

                                                                  100000  r
   • RAT LCW. 4 h. CONTINUOUS
   • CAT. CNS EFFECTS 5 MN. CONTINUOUS

   • MOUSE. CNS EFFECTS. 30 MIN, CONTINUOUS
   • MOUSE. CNS EFFECTS. 1 h CONTINUOUS
   O MOUSE CNS EFFECTS 2 h. CONTINUOUS
-  • MOUSE. DEATH KIDNEY TOXICITY 1-3 h. CONTINUOUS
          • MOUSE REPRODUCTIVE EFFECTS 5 DAYS INTERMITTENT
   • RAT LIVER TOXICITY 4 h CONTINUOUS
   • MOUSE LIVER TOXICITY 4 h CONTINUOUS
     RAT AND MOUSE. FRANK DEVELOPMENTAL TOXICITY
     10 DAYS INTERMITTENT

   O RAT DEVELOPMENTAL TOXICITY 10 DAYS INTERMITTENT
   • RAT RABBIT GUINEA PIG LIVER AND KIDNEY EFFECTS
     6 MONTHS INTERMITTENT
                                                                   10000
                                                                    1000
                                                                     100
                                                                      10
                                                                              ANESTHESIA ACUTE
A ANESTHESIA ACUTE

A DIZZINESS TIREDNESS
  HEADACHES
  VERTIGO 3 MIN
                                                                            A DIZZINESS
                                                                               VERTIGO 30 MIN
                                                                               SLIGHT CNS EFFECTS
                                                                               OCCUPATIONAL
                                                                               LONG-TERM
                                                                             A LIVER TOXICITY
                                                                               OCCUPATIONAL
                                                                               LONG-TERM
           i LOAEL FOR ANIMALS   O NOAEL FOR ANIMALS
           , LOAEL FOR HUMANS    A NOAEL FOR HUMANS
                       Fif.2.1.  Effects of chloroform—iahaladoo exponre.

-------
12     Section  2
 ANIMALS
(mg kg/day)

 1000
                                                                      HUMANS
                                                                    (mg/kg/day)

                                                                      1000 r~
  100
  • MOUSE DECREASED LONGEVITY 78 WEEKS
  • RAT LD». SINGLE DOSE
  • RAT REPRODUCTIVE TOXICITY 13 WEEKS
  • RAT. DECREASED SURVIVAL 90 DAYS

  O MOUSE DECREASED LONGEVITY 78 WEEKS

 /O RAT REPRODUCTIVE TOXICITY 13 WEEKS
 !• MOUSE. DECREASED SURVIVAL. 6 WEEKS RAT UVER AND KIDNEY
    TOXICITY 13 WEEKS

  • MOUSE L0» SINGLE DOSE

  • RAT DECREASED LONGEVITY LIVER TOXICITY  78 WEEKS

 f O RAT DECREASED SURVIVAL. 90 DAYS
< O MOUSE DECREASED SURVIVAL 6 WEEKS RAT LIVER TOXICITY 80 WEEKS
 I • MOUSE KIDNEY TOXICITY 80 WEEKS
 I • RAT LIVER TOXICITY 10 DAYS MOUSE LIVER TOXICITY 90 DAYS
 IO RABBIT DEVELOPMENTAL TOXICITY 12 DAYS
  • MOUSE. LIVER TOXICITY 90 DAYS
  O MOUSE. UVER TOXICITY 90 DAYS
  • MOUSE. KIDNEY TOXICITY 14 DAYS
 [• DOG LIVER TOXICITY. 18 WEEKS
\ • MOUSE UVER TOXICITY SINGLE DOSE
 lO RAT LIVER AND KIDNEY TOXICITY 13 WEEKS

  O RAT UVER TOXICITY 10 DAYS
  O MOUSE UVER AND KIDNEY TOXICITY SINGLE DOSE
  O MOUSE MONEY TOXICITY 80 WEEKS
  • DOG LIVER TOXICITY 7 S YEARS
                                                                              100  —
                                                                               10
  10  «—
                                                                              0 1
                                                                                    A DEATH SINGLE
                                                                                       DOSE
                                                                                       LIVER AND
                                                                                       KIDNEY
                                                                                       TOXICITY
                                                                                       1-5 YEARS
              • LOAEL FOR ANIMALS
              O NOAEL FOR ANIMALS
                                LOAEL FOR HUMANS
                                NOAEL FOR HUMANS
                         Fif.24. Effects of cUorofofB—onl

-------
                                                           Health  Effects Summary    13
 ANIMALS
(mg/kg/day)

  100  i-  • RABBIT. KIDNEY TOXICITY. 24 h
                                                                    HUMANS
   10
QUANTITATIVE DATA
WERE NOT AVAILABLE
                                      LQAEL
                       Fig. 2J.  Effects of chloroform—dermal exposure.

-------
 14    Section 2
ACUTE INTERMEDIATE CHRONIC
(S14 DAYS) (15-364 DAYS) (2365 DAYS)
DEVELOP- TARGET REPRO- TARGET TARGET
LETHALITY MENTAL ORGAN DUCTIVE ORGAN ORGAN CANCER
(ppm)
10.000

r«r
    1000
     100
      10
     0 1
    001
   0001
  00001
 000001
0 00000T
        -•m
            r RAT
            m MOUSE
            g GUINEA PIG
            h RABBIT
                                     • m
         • r (LIVER)
r   • m   • m (LIVER)
                               r. h. g (LIVER AND KIDNEY)

                                    A (LIVER)
        I
LOAEL AND NOAEL
IN THE SAME
SPECIES
 !  MINIMAL RISK
 «  LEVEL FOR
"^EFFECTS OTHER
   THAN CANCER
                                                                       ,-4
                                                                      10
                                                   ID'5 ESTIMATED
                                                        UPPER-BOUND
                                                        HUMAN
                                                        CANCER
                                                   10-6 RISK LEVELS
                                                   10
                                                                       ,-7
                          •  LOAEL FOR ANIMALS
                          O  NOAEL FOR ANIMALS
                          A  LOAEL FOR HUMANS
              Fig. 2.4. Leveb of «ig»ifl>«ii« exporare for chloroform—iakdatioa.

-------
                                                             Health  Effects Summary    15
ACUTE
(S14 DAYS)
DEVELOP
LETHALITY MENTAL

TARGET
ORGAN
INTERMEDIATE
(15-364 DAYS)
HEPRO-
LETHALITY DUCTIVE

TARGET
ORGAN
                                                                                   CHRONIC
                                                                                  <> 36S DAYS)
                                                                         DECREASED   TARGET
                                                                         LONGEVITY    ORGAN   CANCER
(mg kg/day)

   1000




    100




     10
   0 1
  001
  0001
 00001
000001
                  Oh
                                r (LIVER)
                      m(UVER)
                                   •
                             »     T
                    r  RAT
                   m  MOUSE
                   h  RABBIT
                   d  000
I     r     ,
 ,  MINIMAL RISK LEVEL
 '  FOR EFFECTS OTHER
^ THAN CANCER
                                 I
   LOAEL AND NOAEL IN
   SAME SPECIES
                      m(UVER)f
                             0
        f
        T

        1
        0
                                                                 ' (LIVER
                                                                 K.DNEY)
                                                                   «d (LIVER)
• m

0   r (LIVER)
      .
      6
• LOAEL FOR ANIMALS
O NOAEL FOR ANIMALS
A LOAEL FOR HUMANS
A NOAEL FOR HUMANS
                                                                « m
                                                                .,
                                                         (KIDNEY) • m
                                                        1       • '
                                                        ° f d (LIVER)
                                                                                  (LIVER) A
                                                                                              10"  -
                10-' -

             ESTIMATED
             UPPER-BOUND
             HUMAN
             CANCER
             RISK LEVELS
                       Fig. L5.  Levcb of significant exposure for chlorofonn—oraL

-------
16   Section 2
(mg/kg/day)

   100 r-
    10
               ACUTE
             (514 DAYS)

           TARGET ORGAN
• h (KIDNEY)
                  INTERMEDIATE
                  (15-364 DAYS)
QUANTITATIVE DATA
WERE NOT
AVAILABLE
                            CHRONIC
                           (* 365 DAYS)
QUANTITATIVE DATA
WERE NOT
AVAILABLE
                     h RABBIT
                     • LOAEL FOR ANIMALS
             Fig. 2.6.  Lefcbofripfflcut
                            for

-------
                                             Health Effects Summary   17

of 1025 ppm for 1 to 3 h was  fatal  to  mice.  These  FELs  are displayed as
LOAELs under acute exposure  in Figs. 2.1  and 2.4.  No  data were available
regarding decreased longevity of  animals  due to  longer-term inhalation
exposure to chloroform.
     Systemic/target organ toxicity.   Target organs for chloroform
toxicity are the liver,  kidney, and central  nervous system  (CNS). CNS
toxicity is usually observed at very high exposures.  In humans,  levels
of 20,000 to 40,000 ppm were  used to produce anesthesia (NIOSH 1974);
levels <1SOO ppm are insufficient to produce anesthesia (Goodman and
Oilman 1980); dizziness and vertigo occurred at  920 ppm for 3-min
(Lehman and Hasegawa 1910, Lehman and  Schmidt-Kehl 1936), and no
symptoms were reported by subjects  exposed to 390  ppm for 30  min (EPA
1985a). For longer-term exposures,  occupational  exposure to >77  ppm
resulted in symptoms of tiredness and  depression,  whereas levels of  22
co 71 ppm resulted in less severe manifestations of these symptoms
(Challen et al. 1958). CNS effects  in  animals include disturbed
equilibrium in cats at 7200 ppm for 5  min. deep  narcosis in mice at  4000
ppm for 30 min, slight narcosis in mice at 3100  ppm for 1 h,  and no
obvious effects at 2500 ppm for 2 h (EPA 1985a). These levels are
plotted in Fig. 2.1, but not in Fig. 2.4 because effects on the  liver
and kidney occur at lower exposure levels, and only the most  sensitive
target organ effect for each species is plotted in Fig. 2.4.
     The liver and kidney are the most sensitive targets for  systemic
toxicity. Phoon et al. (1983) reported cases of toxic jaundice among
factory workers at occupational exposures of 14.4 to >400 ppm.  High
incidences of toxic hepatitis and liver enlargement were found in
workers exposed to chloroform at levels of 2 to 205 ppm for 1 to 4 years
(Bomski et al. 1967). The lower end of this range (2 ppm)  is  plotted in
Figs. 2.1 and 2.4. However,  because the exact exposure level associated
with liver effects in humans exposed by inhalation cannot be determined.
no minimal risk level was derived from these data.

     Liver (and kidney) effects have been observed in  rats and mice
after acute inhalation exposures, and in rats, rabbits, and guinea pigs
after intermediate exposure. None of the studies define NOAELs.   In a
study by Kyiin et al. (1963), fatty infiltration occurred in mice at 100
ppm for 4 h (LOAEL), and dose-related liver necrosis occurred at 200,
400, and 800 ppm (FELs). Thus, 100 ppm is a short-term inhalation LOAEL
for liver effects in mice and is plotted  in Figs. 2.1  and 2.4 for acute
exposure. A 4-h TC50 of 120 ppm for liver damage was reported for rats
and is represented as an acute LOAEL for  liver effects in rats  in Figs.
2.1 and 2.4. For intermediate exposure, 25 ppm, 7 h/day, 5 days/week for
6 months is a LOAEL for liver effects (lobular granular degeneration and
focal necrosis) and kidney effects  (cloudy  swelling) in rats, rabbits,
and guinea pigs in a study by Torkelson et  al.  (1976).  Higher levels (50
and 85 ppm) resulted in more severe effects  in  rats. The 25-ppm level  is
plotted in Figs. 2.1 and 2.4 as a LOAEL for  target organ effects for
intermediate exposure and is the basis for  the minimal risk  level for
intermediate inhalation exposure. Since most  studies in animals were
conducted to provide information relevant to  the  clinical use of
chloroform as an anesthetic, no chronic  inhalation study data were
available.

-------
 18   Section 2

      Developmental toxicity.  No data regarding human developmental
 effects of chloroform were available. A study by Schwetz et al.  (1974)
 defines a NOAEL and FELs for developmental effects in rats exposed by
 inhalation. Exposure of pregnant rats to 30 ppm (NOAEL)  7 h/day  on days
 6 to 15 of gestation resulted in no effects on the offspring,  whereas
 100 ppm (FEL) caused increased incidences of missing ribs,  imperforate
 anus, subcutaneous edema, and delayed ossification of sternebrae,  and
 300 ppm (FEL) caused abnormalities of the skull and sternum,  decreased
 numbers of live fetuses/litter,  and increased resorptions.  The NOAEL and
 lower FEL for rats are plotted in Figs.  2.1 and 2.4 under acute
 exposure.  The NOAEL is the basis for the minimal risk level for  acute
 inhalation exposure.  Exposure of pregnant mice on various days of
 gestation to 100 ppm for 7 h/day resulted in frank effects,  such as
 increased numbers of resorptions and increased incidences of cleft
 palate (Murray et al.  1979). This level  in mice is also  indicated  in
 Figs. 2.1  and 2.4.

      Reproductive tozicity.   The only data regarding reproductive
 effects of inhalation exposure to chloroform are that exposure of  male
 mice to 400 or 800 ppm,  4 h/day  for 5 days caused significant increases
 in the percentage of abnormal sperm (Land et al.  1981)  (see Figs.  2.1
 and 2.4).

      Genotoxicity.  Mixed results were obtained in sister chromatid
 exchange (SCE)  assays  in cultured human  lymphocytes (Sect.  4.3.5 on
 genotoxicity in toxicological data section).  Studies on  the in vitro
 genotoxicity of chloroform reported negative results in  bacteria,  mixed
 results in yeasts, and negative  results  for gene mutations and
 chromosome aberrations in mammalian cells.  In vivo gene  mutation tests
 in Drosophila and DNA  damage in  rats and mice were negative,  whereas
 tests for  chromosome aberrations and sperm abnormalities were mixed.

      Carcinogenicity.  Data  regarding the carcinogenicity of inhaled
 chloroform in humans and animals were not available.  Studies in  animals
 indicate that chloroform is  carcinogenic by the oral route.  NCI  (1976)
 found dose-related increased incidences  of hepatocellular carcinoma  in
 male  and female mice treated by  gavage at time-weighted  average  (TWA)
 doses of &138 mg/kg/day  5  days/week for  78 weeks,  and a  dose-related
 increased  incidence of kidney epithelial tumors in male  rats similarly
 treated by gavage at 90  and  180  mg/kg/day.  Roe et al.  (1979)  found an
 increased  incidence of kidney epithelial tumors in male  mice given 60
mg/kg/day  6 days/week  for  78 weeks.  Dose-related increased Incidences of
 renal tubular cell adenomas  and/or carcinomas were found in male rats
 treated with chloroform  in the drinking  water at levels  equivalent to
dosages 238 mg/kg/day  for  104 weeks (Jorgenaon et al.  1985).

     The EPA  (1985a) considered  these five data sets in  determining  the
q * for chloroform. The  five data sets were (1)  liver tumors in  female
mice  (NCI  1976),  (2) liver tumors in male mice (NCI 1976).  (3) kidney
 tumors in male rats (NCI 1976),  (4)  kidney tumors in male mice (Roe  et
al. 1979),  and 5)  kidney tumors  in male  rats  (Jorgenson  et al. 1985).
EPA (1985a) used  available pharmacokinetic data to calculate an
effective dose for these studies,  assuming that the amount metabolized
to reactive metabolites  is the gavage dose minus the amount excreted
unchanged.  For mice given  60 mg/kg,  as in the Roe et al.  (1979)  study,

-------
                                             Health Effects Summary   19

the correction was 6%. For rats at the sane dosage, it was 20%. In the
NCI (1976) study in which rats and mice received doses of -200 to 500
mg/kg/day, a 20% correction was considered conservative and would
probably overestimate the amount metabolized from these doses. EPA
(198Sa) used these correction factors to reduce the administered dose by
the unmetabolized portion (6% in mice and 20% in rats when given as a
bolus by gavage in corn oil, 0% when administered in drinking water).
Doses were also corrected for differences between animal and human
pharmacokinetics by using a surface area correction. Using these
corrected doses, maximum likelihood estimates of the parameters of the
multistage model were calculated for each of the five data sets. EPA
(198Sa) chose the mouse liver tumor data from the NCI (1976) study as
the basis of the potency factor for inhalation exposure to chloroform.
The NCI (1976) study is considered to be appropriate for use in the
inhalation risk estimate because there were no inhalation cancer
bioassays and no pharmacokinetic data to contraindicate the use of
gavage data (EPA 1987b). The geometric mean of the estimates for male
and female mice in the NCI (1976) study, 8.1 x 10'2 (mg/kg/day) *1. was
recommended as the inhalation q.* for chloroform. EPA (198Sa) combined
the estimates for both data sets because the data for males included
observations at a lower dose, which appeared to be consistent with the
female data. EPA (1985a) noted that the recommended q * was similar  to
the geometric mean calculated from all five estimates and was also
similar to the estimate calculated if data for both sexes of B6C3F1 mice
in the NCI (1976) study were pooled. Expressed in terms of concentration
in air, the qi* is equal to 2.3 x 10'5 (jig/m3)'1 or 1.1 x 10'4  (ppb)'1.

     The concentrations in air associated with individual lifetime
upperbound risks of 10'4, 10'5, 10'6, and 10'7 are 4.3 x 10'3  4.3 x
10'4,  4.3 x ID'5, and 4.3 x 10'6 mg/m3 (8.8 x 10'4, 8.8 x 10'5, 8.8  x
10'6,  and 8.8 x 10*7 ppm), respectively, assuming that a 70-kg human
breathes 20 m3 air/day. The 10'4 to 10'7 levels are indicated  in  Fig.
2.1.

2.2.1.2  Oral

     Lethality and decreased longevity.  A fatal oral dose of  chloroform
may be as little as 10 mL (14.8 g or 211 mg/kg for a 70-kg human)
(Schroeder 1965). This dose is plotted in Figs. 2.2 and 2.5 for acute
lethality. Longer-term exposure levels causing death in humans were  not
available.

     A wide range of oral U>SO values have been reported  for  rats and
mice.  The lowest were 444 mg/kg in 14-day-old rats  (Kimura et al.  1971)
and 118 mg/kg in an especially sensitive strain of mice  (Hill 1978).
These levels are plotted in Figs. 2.2 and 2.5 for acute  lethality.

     Increased mortality was reported in oral studies of  intermediate
duration. In mice, gavage doses of £150 mg/kg/day, but not £60
mg/kg/day, 6 days/week for 6 weeks resulted  in Increased  rates of
mortality (Roe et al. 1979). Thus, 150 mg/kg/day is  the  lowest FEL and
60 mg/kg/day is the NOAEL for increased mortality  for  intermediate oral
exposure in mice. In rats, 90-day exposure to 2500 ppm  in drinking water
resulted in increased mortality, whereas exposure  to 3500 ppm did not
(Chu et al. 1982a). Assuming that a 0.35-kg  rat consumes  0.049 L of

-------
 20   Section 2

 water per day (EPA 1985b),  the 2500-ppm PEL and 500-ppm NOAEL for
 mortality for Intermediate  oral exposure in rats are  equivalent  to doses
 of 350 and 70 mg/kg/day. respectively.  Levels  are plotted in  Figs. 2 2
 and 2.5.

      For chronic exposures,  effects  on  survival were  observed in studies
 in rats and mice. In rats,  gavage doses of  a90 mg/kg/day for  78  weeks
 followed by 33 weeks observation resulted in dose-related increased
 mortality, due perhaps to liver toxicity (NCI  1976).  In mice,  a  gavage
 dose of 477 mg/kg/day for 78 weeks followed by 14 to  15 weeks
 observation resulted in decreased survival,  whereas doses <238 mg/kg/day
 did not (NCI 1976).  The FELs and NOAELs for increased mortality  for
 chronic oral exposure for rats and mice are indicated in Figs 2 2
 and 2.5.

      As seen from Fig. 2.5,  increased mortality in mice in chronic
 studies did not appear to occur at gavage doses that  resulted in death
 in acute experiments.  The discrepancy is explained primarily  by  strain
 differences in sensitivity  to chloroform.

      Systemic/target organ  tozicity.  The liver and kidney are the
 target organs of oral exposure to chloroform.  Levels  of acute oral
 exposure that result in liver and kidney effects in humans were  not
 available.  A patient who ingested 1.6 to 2.6 g/day in cough medicine for
 -10 years developed  hepatitis and nephrosis (Wallace  1950). The  presence
 of other materials in the cough medicine and the fact that the subject
 also ingested moderate amounts of alcohol,  a known liver toxicant, make
 this study unsuitable for derivation of minimal risk  levels.  No  evidence
 of liver or kidney disease,  based on liver  and kidney function tests,
 were found in volunteers who were exposed for  1 to 5  years to -68 mg/day
 chloroform in a dentifrice or -197 mg/day in a dentifrice and mouthwash
 (OeSalva et al.  1975).  The authors calculated  an equivalent ingestion of
 0.96 mg/kg/day for a 50-kg adult exposed to the higher  dosage, which was
 assumed to  be 25% ingested.  The dosage  of 0.96 mg/kg/day is a chronic
 oral NOAEL for liver and kidney effects.  The human NOAEL is indicated  in
 Figs.  2.2  and 2.5 for  chronic oral target organ toxicity.

     Two  acute studies define a LOAEL and a NOAEL for liver effects  in
 mice. Jones  et al. (1958) observed fatty infiltration in the  livers  of
 mice after  a single  dose of  30 mg/kg (LOAEL) and centrilobular necrosis
 at  133  mg/kg (FEL).  Moore et al.  (1982)  found  no toxic  effects on the
 livers  of mice after single  doses of 18  mg/kg  (NOAEL) or 60 mgAg, but
 increased serum glutaaic-oxaloacetic transaminase (SCOT) occurred at 199
 mg/kg-  The  18 mgAg  dose is  also a NOAEL for kidney effects in mice, but
 at  60 mg/kg/day,  there was increased kidney weight, tubular necrosis.
 and tubular  regeneration. The acute  oral NOAEL (18 mgAg)  and LOAEL  (30
 mgAg)  for  target organ toxicity in  mice are Indicated  on Figs.  2.2  and
 2.5. The NOAEL is the  basis  for the  minimal risk level  for acute oral
 exposure.

     Condie  et al. (1983) observed adverse  effects on the kidneys of
mice administered gavage doses of fc37 mgAg/day chloroform in corn oil
 for 14 consecutive days. The lowest  dose used  in this study,  37
"gAg/day,  is  a  LOAEL  for kidney effects in short-term  oral exposure  in
mice (Fig. 2.2).  Because this is not the most  sensitive target organ

-------
                                             Health Effects Summary   21

effect observed in short-term oral exposures in mice,  it is not
presented in Fig. 2.5.

     A teratology study provides dose-response data for liver effects
for short-term oral exposure of rats. No effect occurred in pregnant
rats treated at 20 mg/kg/day (NOAEL) for 10 days during gestation,  fatty
infiltration occurred at SO mg/kg/day (LOAEL), and hepatitis occurred at
316 mg/kg/day (PEL) (Thompson et al. 1974). The acute oral NOAEL and
LOAEL for target organ effects in rats are indicated on Figs. 2.2 and
2.5. Short-term oral exposure of rats also resulted in kidney effects,
but only at doses much higher than those that caused liver effects
(Sect. 4.3.2.1 on systemic/target organ toxicity in the toxicological
data section).
     Intermediate duration studies define a NOAEL and LOAEL for liver
effects in mice for oral exposure. In a study by Hunson et al. (1982),
the lowest dose tested, 50 mg/kg/day (LOAEL) by gavage for 90 days,
resulted in increased relative and absolute liver weights accompanied by
slight histopathological changes. In a drinking water study, exposure Co
200 ppm (40 mg/kg/day) for 30 to 90 days was a NOAEL, whereas >400 ppm
(>80 mg/kg/day) resulted in mild hepatic centrilobular fatty changes
(Jorgenson and Rushbrook 1980).  The intermediate oral NOAEL and LOAEL
for liver effects in mice are indicated in Figs. 2.2 and 2.5.

     Intermediate exposure studies found liver and kidney effects in
rats.  Gavage dosing of rats with toothpaste containing chloroform, 6
days/week for 13 weeks, resulted in fatty and necrotic liver changes ac
410 mg/kg/day and increased relative liver and kidney weight at 150
mg/kg/day (LOAEL).  No effects occurred at 30 mg/kg/day (NOAEL) (Palmer
et al. 1979). The intermediate oral LOAEL and NOAEL for target organ
effects in rats are indicated in Figs. 2.2 and 2.5.

     In dogs, treatment with chloroform in gelatin capsules  for 18 weeks
resulted in elevated serum glutamic-pyruvic transaminase (SGPT) at 30
mg/kg/day (LOAEL),  the lowest dose tested (Heywood et al. 1979). This
level is indicated in Figs. 2.2 and 2.5 for intermediate target organ
(liver) toxicity in dogs and is the basis for the minimal risk level  for
intermediate oral exposure.

     Chronic oral studies have reported effects on livers of rats, mice,
and dogs,  and on kidneys of mice. In mice, nonneoplastic proliferative
changes and necrosis occurred in livers at £138 mg/kg/day,  given by
gavage 5 days/week for 78 weeks followed by 15 weeks of observation  (NCI
1976). In mice treated by gavage with chloroform 6 days/week for 80
weeks followed by 16 to 24 weeks of observation, there was  an  increased
incidence of moderate to severe kidney disease at 60 mg/kg/day  (LOAEL),
but not at 17 mg/kg/day (NOAEL) (Roe et al. 1979). The levels  are
indicated on Figs.  2.2 and 2.5.

     In rats, dose-related increased incidences of liver necrosis
occurred at gavage doses £90 mg/kg/day (LOAEL), 5 days/week for  78 weeks
followed by 33 weeks of observation  (NCI 1976). Minor histological
changes in the liver, without evidence of chloroform-induced
hepatotoxicity, were observed in rats treated at 60 mg/kg/day (NOAEL) in
toothpaste,  6 days/week for 80 weeks, followed by 15 weeks  of

-------
 22   Section 2

 observation (Palmer et al.  1979).  The chronic oral NOAEL and LOAEL for
 target organ effects in rats  are  indicated in Figs.  2.2 and 2.5.

    '  Doses of 215 mg/kg/day given by gavage to dogs  6 days/week for 7.5
 years resulted in increased levels of SGPT and other serum enzymes
 indicative of liver damage, as  well as  increased numbers of fatty cysts
 (Heywood et al.  1979).  The  dose of 15 mg/kg/day was  the lowest dose
 tested and is considered a  chronic oral LOAEL for target organ effects
 in dogs (see Figs.  2.2 and  2.5).  The minimal risk level for chronic oral
 exposure was calculated from  this  LOAEL.

      Developmental toxicity.  In  a teratogenicity study, pregnant rats
 were  treated by  gavage with chloroform at 0, 20, 50, and 126 mg/kg/day
 on days 6 to 15  of gestation  (Thompson et al. 1974). No effects occurred
 at 20 mg/kg/day-  No fetal effects  occurred at 50 mg/kg/day, but maternal
 toxicity was evident at this  level and higher. Fetal body weights were
 significantly decreased at  126  mg/kg/day. For reasons discussed in Sect.
 4.3.3.2 on developmental toxicity  in animals after oral exposure in the
 toxicological data section, it  is  not appropriate to define a LOAEL and
 NOAEL for developmental effects in rats from this study. Thompson et al.
 (1974)  also treated pregnant  rabbits with 20, 35, or 50 mgAg/day on
 days  6  to 18 of  gestation and found no treatment-related developmental
 effects.  Thus, 50 mgAg/day is  a NOAEL for developmental effects of
 orally  administered chloroform  in  rabbits (see Figs. 2.2 and 2.5).

      Reproductive toxicity.   The only data regarding reproductive
 effects are that  rats administered gavage doses of 410 mg/kg/day
 (LOAEL),  but not  150 mgAg/day  (NOAEL) 6 days/week for 13 weeks, had
 gonadal atrophy  (Palmer et  al.  1979). These levels are indicated in Fig.
 2.2 and in Fig.  2.5 under intermediate exposure.

      Genotoxicity.   See Sect. 2.2.1.1 on genotoxicity under inhalation
 exposure.

      Carcinogenicity.   Epidemiological studies indicate a possible
 relationship between exposure to chlorinated drinking water and cancer
 of the  bladder,  large intestine, and rectum in humans (EPA 1985a).
 Chloroform is one of several volatile organic contaminants considered to
 have  carcinogenic potential, but it has not been identified as the sole
 or primary cause  of excess  cancer  rates associated with chlorinated
 drinking water.

      Studies in animals indicate that chloroform is  carcinogenic. NCI
 (1976)  found dose-related increased incidences of hepatocellular
 carcinoma  in male and female mice  treated with chloroform in corn oil by
 gavage  at  a TWA dose of 138 mgAg/day and above, 5 days/week for 78
weeks,  and a dose-related increased incidence of kidney epithelial
 tumors  in  male rats treated by  gavage at 90 and 180  mgAg/day 5
 days/week  for 78  weeks.  An  Increased incidence of epithelial tumors of
 the kidney occurred in  male mice given 60 mg/kg/day. but not 17
mgAg/day  6  days/week for 78 weeks (Roe et al. 1979). Dose-related
 increased  incidences of renal tubular cell adenomas  and/or carcinomas
were  found in male  rats treated with chloroform in the drinking water at
 levels  equivalent to dosages 238 mgAg/day for 104 weeks  (Jorgenson et
al. 1985).  Doses  associated with increased incidences of  tumors  in these
studies are  indicated in Fig. 2.5.

-------
                                             Health Effects Summary   23

     EPA (1987b) chose the study by Jorgenson et al.  (1985) as the basis
for the q.  for oral exposure to chloroform because administration via
drinking water better approximates oral exposure of humans than does
administration in corn oil by gavage in the NCI (1976)  study.  Based on
the incidence of renal tumors in male Osborne-Mendel rats, the q * was
calculated to be 6.1 x 10*3 (mg/kg/day)"1.  The oral doses associated
with individual lifetime upper-bound risks  of
10-4  10-5f 10-6f and 10-7 are 1.6 x 10'2,  1.6 x 10'3.  1.6 x 10'4, and
1.6 x 10*5 mg/kg/day, respectively. These doses are indicated in Fig.
2.5.

2.2.1.3  Dermal

     Lethality and decreased longevity.  Pertinent data regarding
lethality and reduced longevity due to dermal exposure  to chloroform
were not located in the available literature.

     Systemic/target organ toxicity.  The only information found was
that dermal applications as low as 100 mg/kg for 24 h caused
degenerative changes in kidney tubules of rabbits (Torkelson et al.
1976). This one data point is displayed graphically in Figs. 2.3 and
2.6.

     Developmental tozicity.  Pertinent data regarding developmental
toxicity due to dermal exposure to chloroform were not located in the
available literature.

     Reproductive toxicity.  Pertinent data regarding reproductive
effects of dermal exposure to chloroform were not located  in the
available literature.

     Genotoxicity.  See Sect. 2.2.1.1 on genotoxicity under inhalation
exposure.

     Carcinogenicity.  Pertinent data regarding the carcinogenicity of
dermal exposure to chloroform were not located in the available
literature.

2.2.2  Biological Monitoring as a Measure of Exposure and  Effects

     Methods for measuring chloroform in biological fluids, tissues,  and
exhaled breath are available; however, there is relatively little
quantitative information relating monitored chloroform levels  in  tissues
or fluids to exposure levels or toxic effects, possibly  because of
chloroform's volatility and rapid elimination from tissues.   In
addition, the presence of chloroform or its metabolites  in biological
fluids and tissues may result from the metabolism of other chlorinated
hydrocarbons; thus, elevated tissue levels of chloroform or its
metabolites may reflect exposure to other compounds.  The  relationship
between chloroform concentration in inspired air and resulting blood
chloroform levels is the most well-defined measure of exposure due  to
the extensive use of chloroform as a surgical anesthetic.  Smith et  al.
(1973) observed a mean arterial blood concentration of 9.8 mg/dL  (rag  %)
(range 7-16.5) among 10 patients receiving chloroform anesthesia  at an
inspired air concentration of 8000 to 10,000 ppm. Similar findings  were
reported by Goodman and Oilman (1980)  (Table 2.1). Blood chloroform
levels were monitored by Phoon et al.  (1983)  in workers  experiencing

-------
24    Section 2
                     Table 2.1. Relationship of chloroform conceotratioo
                           in inspired air and Mood to anesthesia
                          Condition
In inhaled air
   (ppm)
In blood
(mg%)
                Not sufficient for anesthesia        < 1,500          <2
                Light anesthesia (after induction)    1,500-2,000      2-10

                Deep anesthesia                   2,000-15,000    10-20
                Respiratory failure                 20,000          20-25

                   Source: Goodman and Oilman  1980, EPA 1985a.

-------
                                             Health Effects Summary   25

 toxic jaundice due to chloroform exposure. When workroom air
 concentrations were estimated to be >400 ppm, the blood samples of 13
 workers with jaundice were 0.10 to 0.20 pg/100 mL blood. In another
 group of 18 workers with toxic hepatitis, blood samples revealed
 chloroform in some but not all workers, and workroom air contained 14.4
 to  50.4 ppm on various days. Although these data indicate a trend for
 increased blood concentrations with increased exposure concentration,
 the wide ranges in exposure concentrations associated with wide ranges
 of blood concentrations preclude meaningful graphical display.

     Studies in animals also indicate that blood chloroform level is noc
 a reliable indicator of exposure in animals. Jorgenson et al. (198S)
 measured blood chloroform concentrations in rats chronically exposed to
 chloroform in their drinking water at concentrations of 0 to 1800 mg/L.
 In addition to dose-related increased incidences of renal tubule tumors,
 they observed a general dose-related trend in blood chloroform levels,
 but noted that the levels were highly variable, with standard deviations
 usually greater than the mean. This variability could be a result of the
 very short half-life of chloroform in the blood due to pulmonary
 excretion.  Although monitoring blood chloroform levels appears to be the
 best indication of recent exposure, the sensitivity and reliability of
 this indicator are questionable.

     Wallace et al. (1986a,b) and Wallace (1986) measured the levels of
 chloroform in breathing zone (personal) air, outdoor air, and exhaled
 breath of people residing in industrial urban and rural areas. No
 significant correlation was found in chloroform levels in exhaled breach
 either with personal air or outdoor levels.

     The primary targets of chloroform toxicity are the CNS, liver, and
 kidneys. The signs of CNS effects (e.g., dizziness, tiredness, headache)
 are readily apparent.  Monitoring for effects of lower-level chloroform
 exposure on liver and kidneys involves functional tests. Liver effects
 are commonly detected by monitoring for elevated levels of liver enzymes
 in the serum.  Urinalysis and measurement of blood urea nitrogen are used
 to detect abnormalities in kidney function. The quantitative
 relationship between blood chloroform levels and measurable effects has
not been adequately determined.

2.2.3  Environmental Levels as Indicators of Exposure and Effects

2.2.3.1  Levels found in the environment

     Monitoring data for chloroform in soil were not located.
Chloroform is  found in drinking water as a result of chlorination of
water containing organic matter (Cech et al. 1982, Beliar et al. 1974),
but the association between drinking water levels and biological
 indicators  of exposure has not been defined. Chloroform has also been
detected in various food items (McConnell et al. 1975, Entz et al.  1982,
Lovegren et al.  1979,  Coleman et al. 1981, Pellizzari et al. 1982), but
data are insufficient to predict the average daily intake from dietary
sources, and an association between dietary intake and biological
indicators  of exposure has not been defined.

-------
 26   Section 2

 2.2.3.2  Human exposure potential

      The level of chloroform In chlorinated drinking waters  is expected
 to be highest in areas where raw water supplies have high concentrations
 of humic/fulvic acids, high concentrations of algae, alkaline pH, and
 relatively warm temperatures. These factors contribute to elevated
 chloroform levels in finished drinking waters (EPA 1981). Treatment
 techniques are available to lower the level of chloroform in finished
 drinking waters;  however,  technology is costly, and many communities,
 particularly those serving small populations, may not be able to finance
 such operations.

      Based on the relatively high water solubility of chloroform [8.95 x
 103 mg/L at 20°C  (DeShon 1979)], it is speculated that this  compound
 would be readily  available for uptake from soil by plants. Detection of
 chloroform in a wide variety of food items (HcConnell et al. 1975, Entz
 et al.  1982,  Lovegren et al.  1979, Coleman et al. 1981, Pellizzari et
 al.  1982)  appears to support this prediction. Because of the lack of
 data on this  topic,  it is  not certain what effect environmental
 conditions and soil  characteristics would have on chloroform uptake.

      Monitoring data indicate that people living in highly populated and
 industrial source-dominated areas are exposed to higher levels of
 chloroform in air than people living in urban or rural nonsource-
 dominated  areas (Brodzinsky and Singh 1982).

 2.3   ADEQUACY OF  DATABASE

 2.3.1  Introduct ion

      Section  110  (3)  of SARA directs the Administrator of ATSOR to
 prepare  a  toxicological profile for each of the 100 most significant
 hazardous  substances  found at facilities on the CERCLA National
 Priorities  List.  Each profile must include the following content:

     "(A)  An  examination,  summary, and interpretation of available
           toxicological information and epidemiologic evaluations on a
          hazardous  substance in order to ascertain the levels of
           significant human exposure for the substance and the
          associated  acute,  subacute, and chronic health effects.

      (B)  A determination  of whether adequate information on the health
          effects  of  each  substance is available or in the process of
          development to determine levels of exposure which  present a
          significant risk to human health of acute, subacute, and
          chronic  health effects.

      (C)  Where appropriate, an identification of toxicological testing
          needed  to  identify the types or levels of exposure that may
          present  significant risk of adverse health effects in humans."

     This section  identifies gaps in current knowledge relevant to
developing levels  of  significant exposure for chloroform. Such gaps are
identified for certain health effect "end points" (lethality,
systemic/target organ toxicity, developmental toxicity, reproductive
toxicity, and cancer)  reviewed in Sect. 2.2 of this profile  in
developing levels  of  significant exposure for chloroform, and for other

-------
                                             Health Effects Summary   27

 areas such as  human biological monitoring and mechanisms of toxicity.
 The present section briefly summarizes the availability of existing
 human and animal  data, identifies data gaps, and summarizes research in
 progress  that  may fill such gaps.

      Specific  research programs for obtaining data needed to develop
 levels of significant exposure for chloroform will be developed by
 ATSDR,  NTP,  and EPA in the future.

 2.3.2  Health  Effect End Points

 2.3.2.1  Introduction and graphic summary

      The  availability of data for health effects in humans and animals
 is  depicted on bar graphs in Figs. 2.7 and 2.8, respectively.
      The  bars  of  full height indicate that there are data to meet at
 least one of the  following criteria:

  1.   For  noncancer health effect end points, one or more studies are
      available that meet current scientific standards and are sufficient
      to define a  range of toxicity from no-effect levels (NOAELs) to
      levels  that  cause effects (LOAELs or FELs).

  2.   For  human carcinogenicity, a substance is classified as either a
      "known  human carcinogen" or "probable human carcinogen" by both EPA
      and  the International Agency for Research on Cancer (IARC)
      (qualitative), and the data are sufficient to derive a cancer
      potency factor (quantitative).

  3.   For  animal carcinogenicity, a substance causes a statistically
      significant  number of tumors in at least one species, and the data
      are  sufficient to derive a cancer potency factor.

  4.   There are studies which show that the chemical does not cause this
      health  effect via this exposure route.

      Bars of half height indicate that "some" information for the end
point exists but  does not meet any of these criteria.

      The  absence  of a column indicates that no information exists for
that  end  point and route.

2.3.2.2   Descriptions of highlight* of graphs

      Information  regarding effects of acute inhalation exposure of
humans  to chloroform has come from the former use of chloroform as an
anesthetic. As these exposure levels were high and resulted mainly in
CNS effects, the  data do not adequately characterize other possible
systemic  effects  of inhalation exposure to chloroform in humans. Long-
term  occupational exposure to chloroform may result in slight CNS and
liver effects,  but exposure levels are not well characterized. Thus, the
bars  for  acute and chronic systemic toxicity due to inhalation exposure
indicate  that there are some data (see Fig. 2.7). No data were available
regarding the lethality,  developmental and reproductive toxicity, and
carcinogenicity of inhaled chloroform in humans. For oral exposure,  some

-------
                                          HUMAN  DATA
                                                                                                 Ni
                                                                                                 00
                                                                                                                          •
                                                                                                                          n
                                                                                                                          >~.
                                                                                                                          §
                                                                                                                          K)
                                                                                                       V   SUFFICIENT
                                                                                                       ^INFORMATION*
                                                                                                              SOME
                                                                                                          INFORMATION
                                                                                                               NO
                                                                                                          INFORMATION
                                                                                           INHALATION
                                                                                      DERMAL
LETHALITY
               ACUTE
INTERMEDIATE    CHRONIC   DEVELOPMENTAL  REPRODUCTIVE  CAHCINOOENICITY
 	      /    TOXICITV       TOXICITY
                    SYSTEMIC TOXICITV

                     'Sufficient information exists to meet at least one of the criteria for cancer or noncancer end points.
                       Fig. 2.7. Availability of information on health effects of chloroform (human data).

-------
                                            ANIMAL DATA
                                                                                                        v  SUFFIOEHT
                                                                                                        ^INFORMATION*
                                                                                                       J
                                                                                                               SOME
                                                                                                          'INFORMATION
                                                                                                                NO
                                                                                                           INFORMATION
                                                                                                 OHAL
                                                                                             INHALATION
                                                                                        DERMAL
LETHALITY       ACUTE     INTERMEDIATE    CHROMIC    DEVELOPMENTAL  REPRODUCTIVE  CARCINOOENICITY

           /	/    TOXICITV        TOXICITY
                    SYSTEMIC TOXICITY


                     'Sufficient information exists to meet at least one of the criteria for cancer or noncancer end points.


                       fig. 2.8. Availability of information on health effects of chloroform (animal data).

ro
\O

-------
 30   Section 2

 data exist for acute lethality in humans. The only data  regarding
 systemic toxicity due to chronic  oral  exposure  are that  daily use of
 dentifrices and mouthwashes containing chloroform did not  result in
 evidence of liver or kidney disease. Chlorination of drinking water may
 be associated with an increased risk of cancer, but chloroform is one of
 several contaminants in chlorinated water and has not been identified as
 the only or primary cause of excess cancer rates. Thus,  bars for
 lethality, chronic systemic toxicity,  and carcinogenieity  of oral
 exposure to chloroform indicate some data (see  Fig. 2.7).  No data were
 available for systemic toxicity of acute or  intermediate oral exposure
 or for developmental and reproductive  toxicity  of oral exposure to
 chloroform in humans.  No data were available for dermal  exposure of
 humans to chloroform.

      In animals,  LOSQs for rats and mice were available  for oral
 exposure.  Doses that caused death and  that did  not cause death were
 available for rats and mice for intermediate oral exposure and for mice
 for chronic oral  exposure,  and a  LOAEL for decreased longevity for
 chronic oral exposure  of rats was defined. Thus, the bar for lethality
 of oral exposure  indicates adequate data (see Fig. 2.8). LOAELs and
 NOAELs for target organ/systemic  toxicity were  available for acute,
 intermediate,  and chronic oral exposure of rats and mice,  and data were
 sufficient to derive minimal risk levels for all three durations.
 Although NOAELs were not available from dog  studies, LOAELs in dogs,
 which  were below  the NOAELs in rats and mice, were used  as the bases  for
 the intermediate  and chronic minimal risk levels. Thus,  the bars for
 acute,  intermediate, and chronic  oral  systemic  toxicity  indicate
 adequate data (see Fig.  2.8).  There are adequate data to indicate that
 chloroform is carcinogenic in animals  by the oral route  but only some
 data to indicate  that  oral exposure causes developmental effects.
 Although a LOAEL  and NOAEL for gonadal atrophy  were available for rats,
 reproductive performance was not  assessed; therefore, Fig.  2.8 indicates
 some data  for reproductive effects. For inhalation exposure of animals,
 LCsos  in rats  and mice were the only data on lethality;  thus, the bar
 indicates  some data. For target organ/systemic  toxicity, LOAELs, but  not
 NOAELs,  were available for acute  and intermediate inhalation exposure,
 as  indicated by bars for some data. There were  adequate  data on
 developmental  effects  of inhalation exposure to define a LOAEL and a
 NOAEL  in rats  and to derive a minimal  risk level for acute inhalation
 exposure.  Some data exist for reproductive effects of  inhalation
 exposure,  but  data are lacking for carcinogenicity and systemic toxicity
 of  chronic inhalation  exposure. The only data available  for dermal
 exposure of animals are that application of  chloroform to  the skin of
 rabbits  resulted  in kidney effects.

 2.3.2.3  Summary  of relevant ongoing research

     NTIS  (1987)  listed few studies useful for  filling data gaps
 identified in  the preceding sections.  An ongoing investigation
concerning inhalation  toxicology  of environmental chemicals in rats  and
mice by  B.  Adkins of Northrop Services was identified. This study might
provide  information to fill gaps  in the inhalation database. A study by
W.E. Braselton of Michigan State  University  concerning the mechanism of
 interaction between chloroform and polychlorinated biphenyls  (PCBs)  or

-------
                                             Health Effects Summary   31

polybrominated blphenyls (PBBs) in causing nephrocoxicity in mice and
rats was also identified. This study appeared to be primarily concerned
with mechanisms of toxicity and metabolic pathways. NTIS (1987)  also
listed a study by D.W. Deamer of the University of California-Davis
concerning anesthetic effects on membrane permeability.  This in vitro
study could elucidate the mechanism of action of general anesthetics
like chloroform.

     NTP (1986) plans investigations concerning the effects of time-
varying concentration profiles and patterns of repetitive inhalation
exposures to chloroform on the development of cleft palate in mice.
These studies should add to the animal inhalation developmental effects
database. NTP (1986) also plans to test chloroform in an in vivo mouse
bone marrow cytogenetic test.
     The Japan Bioassay Laboratory in Kanagawa is conducting 14- and
90-day inhalation studies of chloroform in rats and mice for the
Japanese government (Davidson 1988). Chronic studies are also planned.

2.3.3  Other Information Needed for Human Health Assessment

2.3.3.1  Pharmacokinetics and mechanisms of action

     The pharmacokinetics and mechanisms of chloroform toxicity in the
liver and kidneys are relatively well understood. Chloroform is
metabolized to phosgene or some other reactive metabolite, which then
causes toxic effects in liver and kidneys. The mechanism of chloroform
effects on the CNS are less well understood. The liver, kidneys, and CNS
are the primary targets of chloroform toxicity, but the relatively
limited database for inhalation and dermal exposure effects makes  it
difficult to evaluate the appropriateness of route-to-route
extrapolation.  The Dow Chemical Company (1988) has a joint project with
Drs. R. H.  Reitz, M. E. Andersen, R. B. Connoly, and R. J. Corley  to
develop a physiologically based pharmacokinetic model for chloroform,
which is anticipated to be validated and ready for use in 1988.
Additional data concerning method of administration (bolus vs continuous
dosing) and vehicle effects on pharmacokinetics, toxicity, and
carcinogenicity of chloroform are needed to evaluate the appropriateness
of available data for human health effects risk assessment.

2.3.3.2  Monitoring of human biological samples

     Methods for detecting chloroform in exhaled breath, blood,  urine,
and tissue are available, but monitoring data of humans  for  exposure to
chloroform in relation to health effects or for  indicators  of  exposure
are inadequate due to chloroform's volatility and  short half-life  in
tissues. In addition, the presence of chloroform or its metabolites  in
biological fluids and tissues may result from the  metabolism of other
chlorinated hydrocarbons; thus, elevated tissue  levels  of  chloroform or
its metabolites may reflect exposure to other compounds.

-------
32   Section 2

2.3.3.3  Environmental considerations

     Although chloroform has been detected In some foods and beverages,
data regarding the average daily dietary intake were not located.

     Limited data are available on the persistence of chloroform in the
environment, particularly in surface waters, soil, and groundwater.
Although the half-life of chloroform in surface water was estimated,
significant uncertainty exists. Due to the lack of data it was not
possible to estimate the half-life of chloroform in either soil or
groundwater.

     No studies were available regarding the chemical interaction
between chloroform and other pollutants in the environment.

     There are no known ongoing experimental studies intended to fill
the data gaps on the environmental fate and transport of chloroform.

-------
                                                                      33
                 3.   CHEMICAL AND PHYSICAL INFORMATION

3.1  CHEMICAL IDENTITY

     Data pertaining to the chemical identity of chloroform are listed
in Table 3.1.

3.2  PHYSICAL AND CHEMICAL PROPERTIES
     The physical and chemical properties of chloroform are presented in
Table 3.2.

-------
34    Section 3
                       Table 3.1. Chemical identity of chloroform
                                          Value
                       References
            Chemical name

            Synonyms
            Trade name


            Chemical formula

            Wiswesser line notation

            Chemical structure
            Identification numbers
              CAS Registry No.

              NIOSH RTECS No.

              EPA Hazardous
              Waste No.

              OHM-TADS No.

              DOT/UN/NA/IMCO
              Shipping No.

              STCC No.
              Hazardous Substances
              Data Bank No.

              National Cancer
              Institute No.
Trichloromethane

Methenyl chloride,
Methane trichloride,
Methyl trichloride,
Formyl trichloride

Freon 20, R 20,
R 20 (refrigerant)

CHC1)

GYGG
                                        C1

                                    H —C —Cl

                                        C1
67-66-3

FS 9100000
Chemline 1987

IARC 1979
IARC 1979


NLM 1987

NLM 1987

IARC 1979
NLM, 1987

NLM 1987
U044                 NLM 1987

7216639              NLM 1987

Chloroform; UN 1888   NLM 1987
49 403 10 (other than
technical grade)
49 403 11 (technical
grade)

56


C02686
NLM 1987

NLM 1987


NLM 1987


NIOSH 1987a

-------
                      Chemical  and Physical Information    35
Table 3.2. Physical and chemical properties of chloroform
Property
Molecular weight
Color

Physical state
Odor

Odor threshold
Water

Air

Melting point. °C
Boiling point. °C
Autoignition
temperature, °C
Solubility
Water
Organic solvents

Density
Vapor density (air = 1)
Partition coefficients
Log octanol/water

Blood/air
Olive oil/air
Vapor pressure
Henry's law constant

Refractive index
Flash point
Flammability limits
Conversion factors
ppm (v/v) to mg/m1
in air (20°C)
mg/m3 to ppm (v/v)
mair(20°C)
Value
119.38
Colorless.
water-white
Liquid
Pleasant, ethereal,
nomrntating

2.4 ppm (w/v)

85 ppm (v/v)

-63.2
61 3

>1000

8.22 X I03 mg/L at 20°C
Miscible with principal
organic solvents
1 485 g/cm3 (20°C)
436

1.97

11.7
563
159mm Hg (20°C)
3.0 X 10~3 atm-mj/mol (20°C)

I.4466(20°C)
None
Unknown


ppm (v/v) - 4.96 mg/m3

mg/m3 — 0.20 ppm (v/v)
References
DeShon 1979
Hawley 1981
DeShon 1979
DeShon 1979
DeShon 1979


Amoore and Hautula
1983
Amoore and Hautula
1983
DeShon 1979
DeShon 1979

DeShon 1979

DeShon 1979
DeShon 1979

Hawley 1981
DeShon 1979

Hansch and Leo
1985
ACGIH 1986
ACGIH 1986
Boublik 1984
Nicholson et
al. 1984
DeShon 1979
DeShon 1979







-------
                         4.  TOXICOLOGICAL DATA

 4.1  OVERVIEW

     Chloroform  is readily absorbed through the lungs and intestinal
 mucosa. Absorption from the gastrointestinal tract is rapid and complete
 and  follows  first-order passive absorptive processes. With oral
 ingestion, a dose-dependent, first-pass effect occurs with pulmonary
 elimination  of unchanged chloroform. Pulmonary uptake occurs by firsc-
 order diffusion  processes. Pulmonary uptake and elimination has three
 components with  rate constants corresponding to tissue loading or
 desaturation of  three major compartments.

     Chloroform  concentrations in tissues are dose related and occur in
 the  following order: adipose > brain > liver > kidney > blood.

     The two major elimination processes for chloroform are pulmonary
 elimination  of unchanged chloroform and metabolism of chloroform in
 liver and other  tissues. Chloroform metabolism is dose dependent and
 saturable. Data  from in vitro and in vivo studies indicate that
 chloroform is metabolized to phosgene via a cytochrome P45Q-dependent
 mechanism. Phosgene or other reactive metabolites are apparently
 responsible  for  the toxic effects of chloroform.

     Because of  large interspecies differences in chloroform metabolism
 and marked sex differences in tissue distribution and covalent binding
 to tissue macromolecules in mice, extrapolating from animal studies to
 man may be difficult.

     Male mice were especially sensitive to the lethal effects of
 chloroform via the oral and inhalation routes. The lowest reported
 effect level for acute lethality was 1025 ppm for inhalation exposures
 and 118 mg/kg for oral exposures. The lowest reported lethal oral dose
 for humans was 211 mg/kg.

     The three principal target organs of chloroform toxicity are the
 liver,  the kidneys,  and the CNS.  Dogs appeared to be the species most
 sensitive to chloroform-induced hepatotoxicity. Liver generally was the
most sensitive target organ,  although the kidneys in male mice of
certain strains were the most sensitive targets. There are a large
number of oral studies but relatively few inhalation studies and almost
no dermal data for the target organ/systemic toxicity of chloroform.

     Possible teratogenic effects of chloroform were observed in mice
exposed to 100 ppm in the atmosphere.  Another study demonstrated
fetotoxic but no teratogenic effects in rats exposed to 30 ppm.
Developmental effects were observed in oral teratogenicity studies in
rats and rabbits. Fetotoxic effects in rabbits occurred at 20 mg/kg/day.
the lowest dose tested in any of these studies, but these effects were
not dose related.

-------
 38    Section  6

      There  Ls little  information concerning the reproductive effects of
 chloroform. Experiments  in animals indicate that chloroform may cause
 sperm abnormalities and  gonadal atrophy.

      Chloroform has been tested for gene mutations in prokaryotes,
 eukaryotes, cultured  mammalian cells, and Drosophila, and for chromosome
 aberrations in vivo and  in cultured mammalian cells. No definitive
 conclusions regarding the genotoxicity of chloroform can be made.

      Epidemiologic studies indicate a possible relationship between
 exposure  to chlorinated  drinking water and cancer of the bladder, large
 intestine, and rectum. Chloroform is one of several volatile organic
 contaminants  present  in  chlorinated drinking water, and it has not been
 identified as the sole or primary cause of excess cancer rates in this
 association.

      Chloroform carcinogenicity has been investigated in a number of
 oral  exposure animal  studies. Positive results included treatment-
 related increases in  incidences of renal epithelial tumors in male
 Osborne-Mendel rats,  hepatocellular carcinomas in male and female B6C3F1
 mice,  kidney  tumors in male ICI mice, and hepatomas in female strain A
 mice.  Negative results were obtained in studies with (C57 x DBA2 Fl)
 mice;  female  Osborne-Mendel rats; female ICI mice and male mice of
 strains CBA,  C57BL, and  CF-1; female &6C3F1 mice; male and female
 Sprague-Dawley rats;  and male and female beagle dogs.

 4.2   TOXICOKINETICS

 4.2.1  Absorption

 4.2.1.1 Inhalation

      Human.   Respiratory absorption of chloroform ranges from 49 to 77%
 (EPA  1980). According to EPA (198Sa), the amount of pulmonary chloroform
 absorption is dependent  on the concentration in inhaled air, the
 duration of exposure, the blood/air partition coefficient, the
 solubility in various tissues, and the state of physical activity, which
 influences the ventilation rate and cardiac output. Pulmonary absorption
 of chloroform is also influenced by total body weight and total fat
content, with uptake  and storage in adipose tissue increasing with
excess body weight and obesity.

      EPA (1985a) noted that in inhalation exposures, the arterial blood
concentration of chloroform is directly proportional to the
concentration in inspired air. At anesthetic concentrations (8000-10,000
ppra),  Smith et al. (1973) and Morris (1951) recorded arterial blood
 concentrations of 7 to 16.5 mg/dL. At lower air concentrations, blood
concentrations were proportionally lower.

     Lehman and Hasegawa (1910) reported that equilibrium between blood
concentration and inhaled air concentration was reached in 80 to  100
min. Total body equilibrium with inspired chloroform concentration
 requires at least 2 h in normal humans at resting ventilation and
cardiac output (Lehmann  and Hasegawa 1910, Smith et al. 1973, EPA
 198Sa). Using data from  Smith et al. (1973) and Lehman and Hasegawa

-------
                                                 lexicological Data   39

 (1910),  EPA (1985a)  calculated  that the retention of chloroform at
 equilibrium was  -65%.

      Animal.   Although systemic toxicity observed in animals after
 inhalation exposure  to chloroform  (see Sect. 4.3 on toxicity) indicates
 that  chloroform  is absorbed by  the lungs, data regarding the rate and
 extent of  absorption were not available from animal studies. Pulmonary
 absorption of  chloroform by animals should be similar to that of humans

 4.2.1.2  Oral

      Human.  Chloroform absorption from the gastrointestinal tract is
 -100% (Fry et  al. 1972). Absorption of an oral dose of 13C-chloroform
 (0.5  g in  a gelatin  capsule) was rapid in humans, with peak blood levels
 in  1  h (Fry et al. 1972, EPA 1985a).

      Animal.   Experiments in mice, rats, and monkeys indicated that oraL
 doses (60  mg/kg) of  14C-chloroform in olive oil were almost completely
 absorbed as  indicated by a 93 to 98% recovery of radioactivity in
 expired air, urine,  and carcass (Brown et al. 1974a, Taylor et al. 1974,
 EPA 1985a).

      Withey  et al. (1983) compared intestinal absorption of chloroform
 administered intragastrically in either water or corn oil to rats and
 found that  absorption was rapid with both vehicles, but that the rate
 and extent of  absorption varied greatly. The peak concentration of
 chloroform  in  blood  after administration in an aqueous medium was 39.3
 Mg/mL when administered in water and 5.9 pg/mL when administered in corn
 oil.  The greater degree of absorption of chloroform in aqueous solution
 compared with  an oily vehicle can be explained by the faster
 partitioning of a lipophilic compound such as chloroform with mucosal
 lipids from an aqueous vehicle than from an oily vehicle. Peak blood
 concentrations occurred slightly more rapidly with the water vehicle
 (5.6  min vs 6.0 min  for corn oil). The authors also noted that the
 uptake from a  corn oil solution was more complex (pulsed) than from
 aqueous solution. They suggested that a possible explanation for this
 behavior was that the chloroform in corn oil was broken up into
 immiscible-globules,  some of which did not contact the gastric mucosa.
 Another possible explanation was that intragastric motility could have
 separated the  doses  into aliquots that were differentially absorbed from
 different sections of the gastrointestinal tract.

      Absorption in mice and monkeys was rapid, with peak blood levels in
 1 h following  oral doses of 60 mgAg chloroform in olive oil (Brown ec
 al.  1974a, Taylor et al.  1974,  EPA I985a).

 4.2.1.3  Dermal

      Human.  No experimental data concerning dermal absorption of
 chloroform by humans were available.  Tsurata (1975) calculated a dermal
 absorption rate of 329 /imol/min/cm2 for shaved abdominal skin of mice.
 equivalent to an absorption of 19.7 mg/min for human absorption if boch
hands were immersed  in liquid chloroform. The calculation was based on
 the assumptions that the rate of chloroform penetration is uniform for
all types of skin and that the total surface area of a pair of human
hands is  800 cm^.

-------
 40   Section 4

      Animal.  Evidence from guinea  pig dermal absorption studies with
 solvents other than chloroform indicated that for solvents such as
 chloroform,  absorption occurs  faster  than metabolism or pulmonary
 excretion (Jakobson et al.  1982,  EPA  1985a).

      Tsurata (1975,  1977)  calculated  a dermal absorption rate of 329
 A  brain > liver >  kidney > blood.

      Chenoweth et al.  (1962) found high concentrations in fat (lOx
 blood)  and adrenals  (4x blood) of dogs after surgical anesthesia,
 whereas  levels in brain, liver, and kidneys were similar to blood.

     Cohen and Hood  (1969)  examined distribution of 14C-chloroform in
 mice at  15 and 120 min after inhalation exposure and found that fat and
 liver were the only  organs  with tissue/blood concentration ratios >2,
 although  kidney and  liver values  increased during the 2-h experiment,
 indicating continuing  accumulation.

     Chloroform crosses the placental barrier, as indicated by
 teratogenic and embryotoxic effects in mice, rats, and rabbits (Murray
et al. 1979,   Dilley  et  al.  1977,  Schwetz et al. 1974, Thompson et al.
 1974) and accumulation in fetal liver (Von Oettingen 1964). Danielsson
et al.  (1986)  found  volatile radioactivity in the placenta and fetuses
of pregnant mice  a short time after inhalation of *4C-chloroform.
Chloroform metabolites  accumulated with time, especially in the amniocic
 fluid. In early gestation,  metabolites accumulated in embryonic neural
 tissues and,   in late gestation, in the fetal respiratory epithelium.

     Chloroform has  been detected in fresh cow's milk and would be
expected  to appear in human milk  as well (EPA 1985a).

-------
                                                 lexicological Data   -.

4.2.2.2  Oral

     Human.  No data concerning distribution of orally administered
chloroform in humans were found in the available literature.

     Animal.  Brown et al. (1974a) found high concentrations  of
radioactivity in body fat and liver of rats and squirrel monkeys given
oral doses of 60 mg/kg 14C-chloroform.

     Taylor et al. (1974) observed highest levels of radioactivity in
liver and kidneys of three strains of mice 3 h after oral dosing with 60
mg/kg l^C-chloroforra. Male mice had 3.5 times more activity in kidneys
than females, and this may be related to the nephrotoxicity observed IP
male mice but not females (Bennet and Whigham 1964;  Culliford and Hewicr
1957; Hewitt 1956; Shubik and Ritchie 1953; Eschenbrenner and Miller
1945a,b; EPA 1985a).  Sex differences in chloroform tissue distribution
were observed only in mice, not in rats or squirrel  monkeys (Brown et
al. 1974a).

     Cohen and Hood (1969) found higher chloroform levels in fat than IP
liver or kidneys following inhalation exposure, whereas Brown et al.
(1974a) and Taylor et al. (1974) found higher levels in liver and
kidneys than in fat following oral exposure. This suggests that
chloroform distribution in mice may depend on the route of
administration and may be related to first-pass extraction by the liver
in oral exposure, differences in observation times after exposure, and
differences in metabolism and binding of metabolites to cellular
macromolecules (EPA 1985a).

4.2.2.3  Dermal

     No data concerning distribution of dermally administered chloroform
in humans or animals were found in the available literature.

4.2.3  Metabolism

     A general scheme of chloroform metabolism is presented in Fig. 4 1
4.2.3.1  Inhalation

     No data concerning metabolism of inhaled chloroform by humans or
animals were found in the available literature.

4.2.3.2  Oral

     Human.  Fry et al. (1972) found that -50% of an oral dose of 0 5 g
chloroform was metabolized to C02 by humans. The fraction metabolized
was dose dependent in that 100% of a 0.1-g dose was metabolized, but
only 35% of a 1.0-g dose was metabolized to C02•

     Chiou (1975) observed that in humans as much as 38% of an oral
chloroform dose was metabolized by the liver, and up to 17% was
eliminated unchanged from the lungs before reaching the systemic
circulation, indicating a first-pass effect.

     Animal.  Pohl and Gillette (1984) summarized available information
concerning chloroform metabolism. Chloroform is metabolized by oxidacive
dehydrochlorination of its carbon-hydrogen bond to form phosgene. The
reaction is cytochrome P450 mediated and occurs in both liver and

-------
 42
Section  6
MAJOR AEROBIC  PATHWAY

                       P450.O2
n w^ig
ACCEPTOR
PROTEIN
1
CO

H2



NADPK
MICROSOMES


,o
//
C-CH-C-OH A
II
S NH
\ /

1 -HCI
O-CCI. H2°
PHOSGENE * 2Hd*C02
* ^^
/ CYSTE»C N.
X CONDENSATION \
^ X
QLUTATHK9NE
CONJUGATES?
                   H
                   o
            2-OXOTHIAZOUDINE-
             4-CARBOXYUC AGO
MINOR  ANAEROBIC PATHWAY
             CHCI3
                      ANAEROBIC
                       NAOPH
                      REDUCED
                     MCROSOMES
                       P45O-F«2<"CO
                                P45O-F* 2*:CCU*HCI
                                     1
                                     CO*2HCI
               Fig. 4.1.  MeUbolk pathways of chlorofonn biotraosfomutioii.

-------
                                                 Toxicological Data   43
       •
kidneys. Phosgene could react with two molecules of glutathione (GSH) co
form diglutathionyl dithiocarbonate,  which is further metabolized in the
kidneys, or it could react with other cellular constituents and cause
cytotoxicity. Experiments with the deuterated derivative of chloroform,
CDC13, further elucidated the mechanism of chloroform metabolism.  CDC13
was 1/2 to 1/3 as cytotoxic as chloroform and was metabolized to
phosgene less rapidly than chloroform in liver and kidney tissue of rats
and mice. These findings indicated that chloroform was metabolized at
its carbon-hydrogen bond to produce toxicity and that phosgene was the
toxic agent.

     Gram et al. (1986) reviewed the  available information concerning
chloroform metabolism in the kidneys. In mice, chloroform is more
nephrotoxic in males than females,  and the difference appears to be
mediated by testosterone. Levels of renal cytochrome P450 and associated
monooxygenases were 3 to 5 times greater in males than in females. In
addition, deuterated chloroform was less toxic than chloroform when
incubated with kidney slices from male mice. Subsequent work showed that
chloroform was metabolized to trichloromethanol, which spontaneously
dehydrochlorinates to yield phosgene. This step is rate limiting,  and
since the C-D bond is stronger than the C-H bond, deuterated chloroform
is less toxic than chloroform. Phosgene may react with tissue components
or water to give C02 and HC1, or with GSH to form 2-oxothiazolidine 4-
carboxylic acid. Results of several studies (Smith and Hook 1983,  1984;
Pohl et al.  1984; Branchflower et al. 1984) indicate that the kidney
itself metabolizes chloroform to phosgene, resulting in local toxicity

     The major end product of chloroform metabolism is carbon dioxide
(Brown et al. 1974a, Fry et al. 1972, Rubinstein and Kanics 1964,  Van
Dyke et al.  1964, Paul and Rubinstein 1963, EPA 198Sa), most of which is
eliminated via the lungs, but some is incorporated into endogenous
metabolites and excreted as bicarbonate, urea, methionine, and other
amino acids (Brown et al. 1974a, EPA 1985a). Inorganic chloride ion is
an end product of chloroform metabolism that has been found in the urine
(Zeller 1883, Van Dyke et al. 1964, EPA 198Sa). Carbon monoxide was
found to be a minor metabolite of chloroform in in vitro  (Ahmed et al
1977,  Wolf et al. 1977) and in vivo studies (Anders et al. 1978, Bellar
et al. 1974, EPA 1985a).

     The extent of chloroform metabolism is variable. Mice, rats, and
squirrel monkeys metabolized 85, 66,  and 28% of an oral dose of 60 rag/kg
^•^C-chloroform to C02 and 2 to 8% to various urinary metabolites  (Brown
et al. 1974a, Taylor et al. 1974, EPA 198Sa). In rats, 67 and 69% of an
oral dose of 12 or 36 mg/kg was metabolized to C02 (Reynolds et al.
1984a,b; EPA 1985a).

     The mode of oral administration and vehicle appear to have an
effect on the metabolism of chloroform. As discussed by EPA (198Sa),
virtually all of the chloroform administered in drinking water would be
absorbed and metabolized to reactive metabolites, but a certain
percentage of a bolus gavage dose would be excreted unchanged. Using the
available pharmacokinetic data, EPA  (1985a) estimated that for rats  and
mice given 60 mg/kg by gavage, the amount of the dose excreted unchanged
would be 6% for mice and 20% for rats. For drinking water
administration, virtually all of the dose would be metabolized.

-------
 44   Section 4

 4.2.3.3  Dei
      No data concerning metabolism of  dermally applied chloroform  in
 humans or animals were found in the available literature.

 4.2.4  Excretion

 4.2.4.1  Inhalation

      Hunan.   Fry et al.  (1972)  observed a three-component elimination
 curve for decline of blood chloroform  concentration in humans. The
 components were a very rapid phase with half-time of 14 min, a slower
 phase with half-time of 90 min,  and a  very slow phase with a very  long,
 but undetermined, half-time.

      Animal.   Kinetics of pulmonary excretion of chloroform are typical
 of gaseous vapor pulmonary elimination for relatively hydrophobic
 volatile gaseous anesthetics  and are best represented by a three-
 compartment first-order model.  The three compartments are vessel-rich
 tissues,  lean body mass,  and  adipose tissue (EPA 198Sa).

      Because  chloroform is quite soluble in body fat, it has a
 relatively long half-time of  elimination from this compartment, -36 h
 (Stewart et al.  1965,  EPA 1985a).  The  elimination half-time for the
 vessel-rich tissues is -30 min  (Lehmann and Hasegawa 1910, EPA 1985a).

 4.2.4.2   Oral

      Human.   Fry et al.  (1972)  observed that 96% (radioactivity) of an
 oral  dose of  500 mg of 14C-labeled chloroform was exhaled as unchanged
 chloroform or C02 by adult humans  within 8 h, and <1% was found in the
 urine. The amount of unchanged  chloroform eliminated via -he lungs
 within 8  h increased in  proportion to  dose.  Lean subject eliminated a
 greater  percentage of the dose  via the lungs than overweight subjects.
 About 50% of  the oral  dose in the  Fry  et al. (1972) study was exhaled as
 C02 and  the rest as unchanged chloroform (Chiou 1975, EPA 1980).

     Animal.   Reynolds et al. (1984a,b) gave rats gavage doses of  12 or
 36 mg/kg  in mineral oil  and found  that 5 and 12%, respectively, were
 excreted  unchanged in exhaled air,  whereas 67 and 68%, respectively,
 were metabolized to C02  and exhaled. Brown et al. (1974a) and Taylor et
 al. (1974) administered  60 mg/kg of 14C-chloroform orally to mice  (three
 strains),  rats,  and squirrel  monkeys and found that they eliminated 6,
 20, and  79%,  respectively,  of the  administered dose via the lungs as
 chloroform or  metabolites other  than C02-  Species differences were
 related to the capacity  to metabolize chloroform rather than differences
 in pulmonary kinetics  (EPA 1985a).  Humans and nonhuman primates
 eliminated chloroform  in  the  breath primarily as unchanged chloroform
 (Brown et al.  1974a,  Fry  et al.  1972),  whereas mice eliminated almost
 80% of an oral chloroform dose  as  C02  (Taylor et al. 1974).

     Mink et al.  (1986)  administered single oral doses of 100 mgAg
 14C-chloroform to rats and mice. In rats,  total recovery was 78% after
 8 h, 65%  of which was  expired unmetabolized chloroform. Another 6.5% was
expired as C02,  2.6% was  excreted  in urine,  and 3.6% was recovered in
organs. Chloroform was metabolized to a greater extent in mice, 26% was

-------
                                                 Toxicological Data   45

expired as unchanged chloroform and 49.6% as C02•  Total recovery was
94.5%, with 13.5% in organs and 4.9% in urine.

     Other routes of chloroform elimination are of minor importance
compared with pulmonary elimination. Brown et al.  (1974a) found
chloroform in high concentration in bile of squirrel monkeys following
oral doses, indicating enterohepatic circulation.  They found only 2, 8,
and 3% of administered radioactivity in urine and feces of monkeys.
rats, and mice, respectively,  within 48 h after dosing.

4.2.4.3  Dermal

     No data concerning excretion of dermally applied chloroform by
humans or animals were found in the available literature.

4.3  TOXIC ITY

4.3.1 Lethality and Decreased Longevity

4.3.1.1  Inhalation

     Human.  No relevant data concerning lethality of inhaled chloroform
in humans were found.

     Animal.   Mice exposed to 2500 ppm chloroform in the atmosphere for
2 h experienced no obvious effects, but 3100 ppm caused narcosis, and
4100 ppm was fatal.  Fatal exposures were 12,300 ppm for rabbits and
16,300 for guinea pigs (Lehman and Flury 1943,  Sax 1979, EPA 1985a)  Von
Oettingen (1955) reported that 8000 ppm was lethal to mice within 3 h,
and 12,500 ppm was lethal within 2 h (EPA 1980). Lundberg et al. (1986)
reported a 4-h inhalation LC50 of 47.7 g/m3 (10,000 ppm) for rats, but
the cause of death was not reported.

     Deringer et al. (1953) exposed C3H mice to -5 mg/L (1025 ppm)
chloroform in the air for 1 to 3 h, and some animals died within 1 day,
thus, 1025 ppm is the lowest reported lethal inhalation level. Kidney
lesions were observed in some of the mice that died.

4.3.1.2  Oral

     Human.  Based on case reports, the mean lethal oral dose for humans
was estimated at -44 g (Gosselin et al. 1976).  A fatal dose may be as
little as 10 mL (14.8 g or 211 mg/kg for a 70-kg human), with death due
to respiratory or cardiac arrest (Schroeder 1965, EPA 1985a).

     Animal.   Reported oral U>50 values are 444 to 2000 mg/kg for rats
and 118 to 1400 mg/kg for mice. Kimura et al. (1971) reported the
following oral LD50 values for rats: 0.3 mLAg  (444 mg/kg) for 14-day -
old rats, 0.9 mLAg (1332 mgAg) for young adults, and 0.8 mLAg  (1184
mg/kg) for older adults. Smyth et al. (1962) reported an oral LD50  of
2.18 mLAg (3226 mgAg) for rats. Chu et al. (1980) reported oral LD50
values of 908 and 1117 mgAg in male and female rats, respectively.
Torkelson et al. (1976) reported an oral LD50 of 2.0 g/kg for male  rats
Liver and kidney lesions were observed. Bowman et al.  (1978) reported
oral LDsos of 1120 mgAg and 1400 mgAg in male and female mice,
respectively. Mice that died had fatty infiltration of  the liver  and
signs of hemorrhage in the kidney, adrenal, lungs, and brain.

-------
 46   Section 4

      Hill (1978) administered single oral doses of chloroform to male
 mice of three different strains.  LDso values  were 0.08,  0.20,  and 0 33
 raL/kg (118,  296, and 488 mg/kg) for DBA/2J,  (B6D2F1)/J,  and C57BL/6J
 mice, respectively. Thus, 118 mg/kg is the lowest reported acute oral
 LD50- Mice that died had liver and kidney lesions.

      Hjelle  et al.  (1982) reported that a single oral  dose of 60 mg/kg
 had no toxic effects on mice.

      Two oral studies of intermediate duration reported  increased
 mortality. Roe et al. (1979)  administered gavage doses of 0,  60,  150, or
 425 rag/kg/day chloroform in toothpaste to groups of 10 mice/sex,  6
 days/week for 6 weeks.  All high-dose mice died,  and 8  of 10 males at 150
 mg/kg died.  The cause of death was not reported.  Weight  gain of females
 was markedly reduced at 150 mg/kg,  and weight gain  of  both sexes was
 moderately retarded at 60 mg/kg.  No other effects were reported.  Chu et
 al. (1982b)  exposed groups of 20  rats/sex to  0,  5,  50, 500,  or 2500 ppm
 chloroform in drinking water  for  90 days.  High-dose rats experienced
 increased mortality.  The rats were emaciated  prior  to  death.
 Histological examination revealed atrophy of  the liver and squamous
 debris  in the esophagus and gastric cardia, indicating that starvation
 was the  cause of death.

      In  a chronic study,  NCI  (1976)  found a dose-related decrease in
 survival at  gavage  doses of 90 or 180 mg/kg/day (males)  or 100 or 200
 nig/kg/day (females)  administered  in corn  oil,  5  days/week,  to  OM rats
 (50/sex/group)  for  78 weeks followed by a 33-week observation  period.

      NCI (1976)  also  administered gavage  doses  of 0, 138,  or  227
 mg/kg/day (males) or  0,  238,  or 448  mg/kg/day (females)  to B6C3F1 mice
 (50/sex/group)  5 days/week for 78 weeks followed by 14 to  15 weeks of
 observation.  Survival of high-dose  females was  decreased relative to
 controls,  but the cause  of death  was  not  reported.

      Heywood et  al.  (1979)  administered 0, 15,  or 30 mg/kg/day
 chloroform in toothpaste  in gelatin capsules  to  beagle dogs
 (8/sex/group)  6  days/week for 7.5 years followed by 20 to  24 weeks of
 observation.  No  effects  on survival,  growth,  organ  weights,
 hematological  parameters,  or  urine  chemistry  were observed.

 4.3.1.3  Dermal

      Pertinent data regarding lethality following dermal exposure of
 humans or  animals to  chloroform were  not  located in the  available
 literature.

 4.3.2  Systemic/Target Organ  Toxlcity

 4.3.2.1  Liver effects

     Overview.   Liver effects  were observed in humans  occupationally
 exposed  to chloroform. Effects  on the  liver have  been  observed in rats.
mice, and  dogs in inhalation  and  oral  studies regardless of the duration
 of exposure.  Dogs appeared  to  be  more  sensitive  to  the hepatotoxic
effects of chloroform in  intermediate  and long-term oral exposures than
 rats or mice. The hepatotoxic  effects  of chloroform appear to  be
mediated by a reactive metabolite which can bind to microsomal protein.

-------
                                                 Toxicologies! Data   67

      Inhalation, human.  Challen et al. (1958) reported that 9 of 10
workers occupationally exposed to chloroform vapors at breathing zone
concentrations of 77 to 237 ppm experienced various symptoms including
thirst, irritability, lassitude, and frequent and burning urination.
Eight of ten employees exposed to 22 to 71 ppm complained of less severe
symptoms. No evidence of liver damage was found in any of these
employees who submitted to liver function tests and medical
examinations.

      Bomski et al. (1967) examined liver size and function in 294
workers in a division of a pharmaceutical plant where chloroform was
used  as a main solvent. The concentration of chloroform in the air of
the production area was 0.01 to 1.0 mg/L (2 to 205 ppm), whereas other
solvents were present in only trace amounts. The groups consisted of 68
people who had worked at the plant for 1 to 4 years and still had
contact with chloroform; 39 people with previous exposure to chloroform;
23 people with a history of viral hepatitis and jaundice, but with no
exposure; and 165 people with no viral hepatitis and no chloroform
exposure. Higher incidences of enlarged livers were found in the
chloroform-exposed groups (25% in those still exposed, 12.8% in those
with  previous exposure) than in the controls (8.7% in the posthepatitis
nonexposed group; 3.7% in the nonhepatitis, nonexposed group). Of those
still exposed who had enlarged livers, 5.9% had toxic hepatitis
(diagnosed on the basis of increased SCOT, SGPT, and serum gamma
globulin), and 82% had fatty livers. The cases of liver disease in the
group still exposed improved when hygienic conditions improved.  Phoon
et al. (1983) reported cases of toxic jaundice among factory workers
occupationally exposed to chloroform. Air analysis revealed that
concentrations were 14.4 to >400 ppm. The lack of suitable controls and
the presence of complicating factors make these studies unsuitable for
risk  assessment (EPA 1985a).

      Inhalation, animal.  Liver effects were also observed in animals
exposed acutely by inhalation. Fatty infiltration of the liver was found
in mice exposed to 100 ppm for 4 h, and dose-related necrosis occurred
at 200,  400, and 800 ppm (Kyiin et al. 1963). Lundberg et al. (1986)
reported a 4-h TC50 of 585 mg/m3 (120 ppm) for liver damage in rats. In
a study of intermediate duration, Torkelson et al. (1976) exposed
several species to 25,  50, or 85 ppm chloroform in the atmosphere
7 h/day,  5 days/week for 6 months, or to 25 ppm 1 to 4 h/day for 6
months.  Exposure to 25 ppm chloroform for up to 4 h/day for 6 months had
no adverse effects on male rats, as indicated by organ and body weights
and gross and histological examination of liver and kidneys. Exposure co
the same concentration for 7 h/day, however, resulted in
histopathological changes in the liver (lobular granular degeneration
and focal necrosis) of rats, guinea pigs, and rabbits. More severe
changes were seen in rats exposed to 50 or 85 ppm for 7 h/day, but not
in guinea pigs and rabbits.

     Oral, human.  Wallace (1950) described a patient who ingested 1.6
to 2.6 g chloroform/day in cough medicine for -10 years. Clinical tests
indicated that he suffered from hepatitis and nephrosis. Although
Wallace (1950) attributed these conditions to the patient's ingestion of
chloroform, there were other materials present in the cough medicine,

-------
 48   Section 4

 and the patient had chronically ingested moderate amounts  of alcohol
 daily until about 1 year prior to the examination.

      Chloroform is acutely toxic to the  liver,  although the  damage  may
 not be fully apparent until 24 to 48 h after  exposure.  Effects  include
 centrilobular necrosis and reduced prothrombin  formation (Goodman and
 Oilman 1980, Wood-Smith and Stewart 1964,  EPA 1985a).

      DeSalva et al.  (1975) investigated  the safety  of  a dentifrice
 containing 3.4% chloroform and a mouthwash containing  0.43%  chloroform
 in two studies lasting 1 and 5 years and involving  229  subjects.  Persons
 using the dentifrice were exposed to -68 mg/day,  while  those using  the
 mouthwash and toothpaste were exposed to -197 mg/day.  There  were  no
 differences in liver function tests (SGPT, SCOT,  and SAP)  between
 experimental and control subjects.  The authors  assumed that  the average
 ingestion of the dentifrice and mouthwash was 25%,  resulting in
 ingestion of 0.34 mg/kg in the first study and  0.96 rag/kg  in the  second
 study,  using an assumed adult weight of  50 kg.

      Oral,  animal.   Three short-term oral  studies in mice  found liver
 effects.  Dose-related increased incidence  and severity  of  centrilobular
 cytoplasmic pallor,  mitotic figures,  and focal  inflammation  in the  liver
 were  observed in mice administered single  gavage  doses  of  37, 74, or 148
 mgAg chloroform in  corn oil compared with controls (Condie  et al.
 1983).  SGPT levels were elevated at the  highest dose. Jones  et al.
 (1958)  observed fatty infiltration in the  liver of  mice after a single
 dose  of 30  mg/kg.  and doses of 133  to 355  mgAg caused  hepatic damage.
 including centrilobular necrosis.  These  doses represent an acute  oral
 LOAEL and PEL,  respectively,  for hepatic effects  in mice.  Moore et  al.
 (1982)  found increased SCOT and uptake of  thymidine in  the livers of
 mice  after  single oral doses of chloroform in corn  oil  at  273 mg/kg or
 in  toothpaste at 199  mgAg.  Doses of -18 and  -60  mg/kg  in  either  vehicle
 did not have any toxic effects  on the liver.  Thus,  18 mgAg  appears to
 be  a  NOAEL  for  short-term oral  exposure  in mice.

      Munson et  al. (1982)  administered aqueous  gavage doses  of 0, 50,
 125,  and  250 mgAg/day to groups  of 7 to 12 male  and 8  to  12  female CD-I
 mice  for  14 consecutive days.  Liver weights were  increased at all doses
 in  females  and  at 125  and 250 mgAg/day  in males. SCOT  and SGPT were
 increased in high-dose females,  and serum  glucose was decreased at  the
 intermediate and high  doses. No effects  were  reported at 50  mgAg/day.

      For  short-term exposure of rats,  a  teratology  study (Sect. 4.3.3.2)
 provided  dose-response data for liver effects.  Thompson et al. (1974)
 observed  fatty  infiltration at  50 mgAg/day (LOAEL) and hepatitis at 316
 mgAg/day (FEL), but no effects at  20 mgAg/day (NOAEL)  were  observed in
 pregnant  rats treated  by corn oil gavage for  10 days during  gestation.
 Torkelson et al.  (1976)  observed gross pathologic changes  in the  liver
 of  rats at  acute oral  doses  of  2250 mgAg- Tumasonis et al.  (1985),
however,  reported that exposure to  chloroform in  drinking  water at  2900
mg/L  (406 mgAg/day)  for 3  weeks  did not cause  histopathological  lesions
 in  the  liver of rats.  The  difference  in  response  in these  studies is
probably  due  to  the different mode  of administration (i.e.,  gavage  vs
drinking water).

-------
                                                 ToxicoLogical Data   i9

     There are several subchronic oral studies chat provide dose-
 response data for liver effects in rats, mice, and dogs.

     Palmer et al. (1979) administered gavage doses of 0, 15. 30. 150,
 or 410 mgAg/day in toothpaste, 6 days/week, to SD rats  (10/sex/group)
 for  13 weeks. High-dose rats experienced increased liver weight with
 fatty change and necrosis. Relative liver weight was affected at 150
 nag/kg, but no effects occurred at lower doses. For intermediate duration
 in rats. 410 mg/kg/day is a PEL. 150 rag/kg/day is a LOAEL, and 30
 mg/kg/day is a NOAEL for liver effects. Subchronic drinking water
 studies report milder liver effects at levels equivalent to higher
 doses. In the 90-day drinking water study by Chu et al.  (1982b) (see
 Sect. 4.3.1.2), rats exposed to 2500 ppm (350 mg/kg/day). but not <500
 ppm  (70 mg/kg/day), had increased frequency of mild to moderate liver
 lesions compared with controls. The severity of these lesions, however,
 was  similar to those seen in controls. Rats treated with drinking water
 containing chloroform at 200 to 1800 ppm (28-252 mg/kg/day) for 90 days
 had  increased incidences of "hepatosis" compared with controls, but the
 incidence was not dose related (Jorgensen and Rushbrook  1980). The
 equivalent doses were calculated assuming that a 0.35-kg rat consumes
 0.049 L water per day (EPA 1985b).

     Bull et al. (1986) administered gavage doses of 0,  60, 130, or 270
 mg/kg/day chloroform in corn oil (or 2% emulphor suspension) to groups
 of 10 B6C3F1 mice/sex for 91 to 94 days. Chloroform administered in corn
 oil had greater hepatotoxic effects than chloroform administered in the
 aqueous suspension. With corn oil as the vehicle, there were  increased
 liver lipid levels and extensive vacuolation of hepatocytes at 60
 nig/kg/day.  There was also extensive disruption of the normal hepatic
 architecture accompanied by infiltration of inflammatory and spindle
 cells at 270 mg/kg/day. Pathology in mice treated with chloroform in 2%
 emulphor consisted of minimal to mild focal necrosis at  130 and 270
 nig/kg/day.

     Jorgenson and Rushbrook (1980) exposed groups of 30 female B6C3F1
 mice to 0,  200, 400,  600, 900, 1800, or 2700 ppm (0, 40, 80, 120, 180,
 360, or 540 mgAg/day) chloroform in drinking water for  up to 90 days.
 There was mild hepatic centrilobular fatty change in all treated groups
 except the 200-ppm (40 mgAg/day) group at 30 days, but  only  in the
 1800- and 2700-ppm dose groups at 60 and 90 days.

     Munson et al.  (1982) administered chloroform as an  aqueous solution
 in emulphor at doses of 0, 50, 125, or 250 mgAg/day to  groups of 7 to
 12 male and 7 to 12 female CD-I mice for 90 days. Liver  weights and
 serum glucose levels were increased in high-dose males.  Liver weights
were increased in all treated females. Treated mice also exhibited
 slight histopathologic changes in liver and kidneys that were not seen
 in controls.  Kidneys of treated mice had small intertubular collections
 of chronic inflammatory cells, mostly lymphocytes. In the liver there
 was generalized hydropic degeneration of hepatocytes and small focal
 collections of lymphocytes. The lowest dose used in this study, 50
mgAg/day,  represents a LOAEL for liver effects in mice.

     Heywood et al. (1979) administered 0, 30, 45, 60, 90, or  120
mgAg/day chloroform in gelatin capsules, 7 days/week, for up  to 18
weeks to groups of one to two beagle dogs/sex/dose. Frequently, elevated

-------
 SO   Section 4

 SGPT, SAP, and SCOT and hepatocyte enlargement  with vacuolization and
 fat deposition were observed at >60 mg/kg/day.  Increased relative liver
 weight, discoloration, and variation in hepatocyte  size  (with  slight fat
 deposition) occurred at 45 mg/kg.  SGPT was  occasionally  elevated  at 45
 and 30 mg/kg/day.  No histopathological effects  were observed at 30
 mg/kg. The lowest dose used in this study,  30 mg/kg/day,  is  considered
 an intermediate-duration LOAEL for liver effects  in dogs because  of
 occasionally elevated SGPT.

      Several chronic studies also  found effects on  the livers  of  rats,
 mice, and dogs.

      NCI (1976)  administered gavage doses of 0, 90.  or 180 mg/kg/day
 (males) or 0,  100,  or 200 mg/kg/day (females) in  corn oil, 5 days/week,
 to OM rats (50/sex/group) for 78 weeks followed by  a 33-week observation
 period. Increased incidences of necrosis  of hepatic parenchyma in males
 and females were dose related.  Palmer  et  al. (1979)  conducted  a study
 with groups of 50  rats/sex receiving gavage doses of 0 or 60 mg/kg/day
 in toothpaste,  6 days/week,  for 80 weeks  followed by 15  weeks  of
 observation.  There  were minor histological  changes  in livers and
 decreased relative  liver weights in female  rats,  but there was no
 evidence of chloroform-induced hepatotoxicity.  Thus, 60  mg/kg/day
 appears to be  a  chronic oral NOAEL,  and 90  mg/kg/day a LOAEL for  liver
 effects in rats.

      NCI (1976)  administered gavage doses of 0, 138, or  227  mgAg/day
 (males)  or 0,  238,  or 448 mgAg/day (females) chloroform in  corn  oil to
 groups of 50  B6C3F1 mice/sex,  5 days/week for 78  weeks followed by 14 to
 15  weeks of observation.  Nonneoplastic proliferative changes and
 necrosis occurred  in livers  of both sexes at both doses.

      Heywood et  al.  (1979) administered 0,  15,  or 30 mg/kg/day
 chloroform in  toothpaste in  gelatin capsules to groups of beagle  dogs
 (8/sex/group), 6 days/week for 7.5  years followed by 20  to 24  weeks of
 observation. No  effects on survival, growth, organ  weights,
 hematological parameters,  or urine  chemistry were observed.  There was a
 moderate dose-related increase  in  SGPT and  other  serum enzymes
 indicative  of liver damage,  which  reached a peak  in the  sixth  year of
 the study but reverted to normal levels after treatment  ended.
 Aggregation of vacuolated histiocytes  ("fatty cysts") occurred in all
 groups;  however, they were larger  and  more  numerous  in treated dogs.
 Therefore,  an oral  dosage of 15 mgAg/day may be  considered  a  LOAEL for
 liver  effects in dogs.

     Dermal.  No dermal toxicity studies showing  effects  of  chloroform
 on  the  liver of humans or animals were found in the  available
 literature.

     General discussion.   Dogs  appear  to be the animal species most
 sensitive to the hepatotoxic effects of chloroform.  Reported adverse
 effect  levels for liver effects in  dogs were below  NCAELs for  rats and
mice in  chronic studies.

     In  vitro studies  indicated that phosgene and other  reactive
chloroform  metabolites bind  preferentially  to lipids and proteins of the
endoplasmic reticulum proximate to  the  P450 metabolic system.  Covalent
binding  also occurs  in other cell  fractions of  the  liver and kidneys,

-------
                                                  Toxicological  Data    51

 especially to mitochondria (Uehleke  and Werner  1975, Hill  et al.  1975
 EPA 1985a).

      Covalent binding of chloroform  metabolites  to  microsomal protein  in
 vitro was enhanced by microsomal  enzyme inducers  and prevented  by
 glutathione.  Brown et al.  (1974b)  proposed a mechanism of  toxicity
 involving formation of a free  radical metabolite  that can  react with
 glutathione,  and,  after glutathione  is  depleted,  with microsomal
 protein,  causing necrosis.  Docks  and Krishna (1976) found  that  only
 those doses  of chloroform causing liver glutathione depletion caused
 liver necrosis.  Ekstrom et al.  (1982) reported  that chloroform  or a
 reactive  metabolite inhibited  glutathione  synthesis. Chlorofsrm
 hepatotoxicity apparently depends  on (1) the rate of its transformation
 to active metabolites and (2)  the  amount of glutathione available to
 conjugate and inactivate metabolites (EPA  1985a). Chloroform is more
 hepatotoxic  in fasted than in  fed animals,  possibly due to decreased
 hepatic glutathione content in fasted animals (Docks and Krishna  1976,
 Brown et  al.  1974b,  EPA 1985a).

 4.3.2.2   Kidney effects

      Overview.   Male  mice  of certain strains are  especially  sensitive  to
 toxic effects of chloroform on kidneys. Kidney  lesions have  been
 observed  in mice after short-term  inhalation exposures and after  short-
 term,  intermediate,  and long-term  oral  exposures. Strain differences in
 susceptibility to  kidney effects  from chloroform  appear to be related  to
 the ability of the  kidney  to metabolize chloroform  to phosgene. Sex
 differences may  be  related  to  testosterone  levels.  Subchronic inhalation
 exposures and short-term and subchronic oral exposures caused adverse
 effects in kidneys  of rats. Kidney lesions  were also observed in  rabbits
 after short-term dermal exposure.  Evidence  that chloroform has  effects
 on the kidneys of humans  is sparse.

      Inhalation, human.  No inhalation data concerning chloroform
 effects on human kidneys were  found  in  the  available literature.

      Inhalation, animal.  Deringer et al.  (1953)  exposed C3H mice to
 -5 mg/L (1025 ppm)  chloroform  in the air for 1 to 3 h and  observed
 kidney lesions in all  of the males but none of the females.  Some  animals
 died  within 1 day and exhibited necrosis of parts of the proximal and
 distal tubules.

      In a study  of  intermediate duration, Torkelson et al. (1976)
 exposed several  species  to  25,  50, or 85 ppm chloroform in the
 atmosphere, 4 or 7 h/day, 5 days/week for 6 months. Exposure to 25 ppm
 chloroform for up to 4 h/day for 6 months had no  adverse effects  on male
 rats, as  indicated by  organ and body weights and  gross and histological
 examination of liver and kidneys. Exposure  to the same concentration for
 7 h/day,  however, resulted  in cloudy swelling of  the kidneys of rats,
 guinea pigs,  and rabbits. More  severe changes were seen in rats (but noc
 in guinea  pigs and rabbits) exposed  to  50 or 85 ppm for 7  h/day.

     Oral, human.  Wallace  (1950) described a patient who  ingested 1.6
 to 2.6 g  chloroform per day in cough medicine for -10 years.  Clinical
 tests indicated  that he suffered from hepatitis and nephrosis.  Although
Wallace (1950) attributed these conditions  to the patient's  ingestion  of

-------
 52   Section 4

 chloroform, there were other materials  present  in  the  cough medicine,
 and the patient had chronically ingested moderate  amounts  of  alcohol
 daily until about 1 year prior to the examination.

      Oral, animal.  Kidney lesions have been  observed  in mice after
 single oral doses. Moore et al.  (1982)  administered  single oral  doses of
 0, 17.3, 65.6, or 273 mg/kg chloroform  in corn  oil or  0, 18.2, 59.2. or
 199 mgAg in toothpaste to groups of 3  to 5 male CFLP  outbred Swiss
 albino mice.  The low dose of -18 mg/kg chloroform in  either  vehicle did
 not have any toxic effects on kidneys of mice or stimulate any
 regenerative activity.  Doses of -60 mg/kg caused an  increase  in  kidney
 weight,  tubular necrosis,  and areas of  basophilia, indicating tubular
 regeneration.  The high doses caused kidney necrosis, increased thymidine
 uptake,  and elevated plasma urea in all animals. Thus, an  acute  oral
 dose of 18 mgAg is a NOAEL for kidney  effects  in mice. The severity of
 toxic effects  was greater  when chloroform was administered in corn oil
 rather than toothpaste.

      These dose -response data are supported by  other short-term  oral
 studies  in mice.  Reitz  et  al.  (1980) observed severe diffuse  renal
 necrosis in male mice after a single oral dose  of 240  mg/kg and  focal
 tubular  regeneration after 60 or 240 mg/kg, but no effects at 15 mg/kg.
 Eschenbrenner  and Miller (1945b)  also observed  renal necrosis in male
 (but not female)  strain A  mice given single intragastric doses of
 >148 mgAg chloroform.  Condie et al. (1983) administered gavage  doses of
 0,  37,  74,  or  148 mg/kg chloroform in corn oil  to male CD-I mice for 14
 consecutive days.  Renal cortical slice  uptake of PAH was decreased at
 the two  highest doses,  and blood,  urea,  and nitrogen levels were
 elevated at the highest dose.  Dose-related increased incidence and
 severity of renal intratubular mineralization,  epithelial  hyperplasia,
 and cytomegaly were observed in kidneys  of treated mice at >37
 mg/kg/day.  Thus,  37 mg/kg/day is  the LOAEL for  kidney  effects for
 short-term oral exposure in mice.

      In  rats,  Chu et al. (1982a)  observed increased kidney weights and
 hematological  and biochemical changes after a single oral  dose of 1071
 ngAg, but  not 756 or 546  mgAg.  Torkelson et al. (1976),  however,
 observed gross pathologic  changes  in kidneys of rats after single oral
 doses S250  mgAg.  Tumasonis et al.  (1985)  reported that exposure to 2900
 mg/L (406 mgAg/day)  chloroform in drinking water for  3 weeks did not
 cause histopathologic lesions in kidneys  of rats. Again, the  difference
 in  response  is probably due to the different mode of administration
 (i.e., gavage  vs  drinking  water).  Rats  exposed  to 5, 50, or 500  ppm
 (0.7, 7,  or  70 mgAg/day)  chloroform in the drinking water for 28 days
 did not  have kidney lesions (Chu et al.  1982a) . Palmer et  al.  (1979)
 reported increased relative kidney weights in rats treated by gavage
 with chloroform in toothpaste,  6  days/week for  13 weeks at 150
          , but not at 230  mgAg/day.
     A chronic oral study also reported effects on the kidneys  of mice.
Roe et al. (1979) administered gavage doses of 0, 17, or 60 mg/kg/day
chloroform in toothpaste or arachis oil to different strains  of mice,  6
days/week for 80 weeks  followed by 16 to 24 weeks of observation. There
were no treatment- related effects on hematological parameters or on  any
tissue except kidneys.  There was an increased incidence of moderate  to

-------
                                                 ToxicologicaL Data   52

 severe  renal  changes, kidney disease, and benign and malignant tumors IT.
 groups  treated with  60 mg/kg/day. The tumor effect was more pronounced
 when chloroform was  administered in arachis oil. No adverse effects
 occurred  in the 17 mg/kg/day group. Thus, 60 mg/kg/day is a chronic oral
 FEL for kidney effects in mice, and 17 mg/kg/day is a NOAEL.

      Dermal,  human.  No data concerning the toxic effects of dermal
 exposure  to chloroform on human kidneys were found in the available
 literature.

      Dermal,  animal.  Dermal applications as low as 1000 mg/kg for 24 h
 caused  degenerative  changes in kidney tubules of rabbits. Dermal effects
 consisted of  slight  hyperemia with moderate necrosis (Torkelson et al
 1976).

      General  discussion.  Hook and Smith (1985) reviewed the available
 information concerning the mechanism of chloroform-induced renal
 toxicity. They concluded that chloroform was bioactivated in the kidney
 by  cytochrome P450 to a metabolite that bound irreversibly to protein
 This  binding  could be diminished by GSH or enhanced by phenobarbital.
 The  identification of a phosgene-cysteine conjugate, 2-oxothizaolidine-
 4-carboxylic  acid, indicated that phosgene was the reactive metabolite
 produced  in the kidney. Bailie et al. (1984) performed several in vitro
 experiments with rabbit kidneys that indicated that chloroform was
 metabolized to phosgene.

      Male mice of certain strains appear to be more sensitive to
 chloroform-induced renal toxicity than other experimental animals. Pohl
 et al.  (1984) found  that sensitivity to chloroform-induced renal
 toxicity  in mice was closely related to the capacity of the kidney to
 metabolize chloroform.  Kidney homogenates from male mice metabolized
 chloroform almost an order of magnitude more rapidly than females.
 Kidney homogenates from males of a sensitive strain metabolized
 chloroform more rapidly than those from a less sensitive strain.

      Renal toxicity of chloroform is probably due to its metabolism in
 the kidney itself rather than the transport of toxic metabolites from
 the liver (EPA 1985a).  McMartin et al.  (1981) reported data indicating
 that  the chloroform metabolite(s) responsible for hepatic and renal
 toxicity are produced in those organs themselves rather than produced
 elsewhere and transported to liver and kidneys.

      Eschenbrenner and Miller (1945b) observed extensive renal tubular
 necrosis in normal male mice and testosterone-treated castrated male
 mice  after oral administration of chloroform; however, necrosis was noc
 observed in normal female mice or nontreated castrated male mice.
 Culliford and Hewitt (1957) also investigated sex and strain differences
 in chloroform renal toxicity.  Adult male CBA and UH mice experienced
 extensive tubular necrosis after inhalation exposure to high
 concentrations for 2 h;  females did not experience necrosis. Treatment
with  androgens rendered females susceptible to renal necrosis, and
 estrogen treatment reduced susceptibility of males. Castration
eliminated the susceptibility of one strain but not the other, however,
susceptibility of the second strain was eliminated when castration was
 followed by adrenalectomy.  In contrast, liver damage also occurred in
almost all exposed mice but was not correlated with sexual hormone

-------
  54   Section 4

  levels. Hill (1978) found that most sensitive strains of mice also
  accumulated the most radioactivity in kidneys when radiolabeled
  chloroform was administered. Strain and sex differences were related to
  testosterone in that females and testosterone-deficient strains were
  less sensitive to renal toxicity. Testosterone may sensitize renal
  tubules to chloroform toxicity via a testosterone receptor mechanism
  (Hill 1978) or by inducing changes in kidney morphology and physiology
  (Eschenbrenner and Miller 1945b).

      Smith et al.  (1984) also investigated hormonal effects on
 chloroform-induced nephrotoxicity in mice.  They found that differences
  in sensitivity were apparently related to renal MFO activity.  Castration
 of males reduced sensitivity and renal cytochrome P450 to levels similar
 to those in females.  Testosterone treatment increased chloroform
 nephrotoxicity and renal cytochrome P45Q levels in both sexes.

 4.3.2.3  CNS effects

      Overview.   The effects  of chloroform on the CNS have been well
 documented as  a result of the use of chloroform as a surgical
 anesthetic.  Concentrations required for the induction of anesthesia  are
 20,000  to 40,000 ppm.  Effects at lower levels include dizziness,
 vertigo,  and headaches at concentrations of -1000 to 1500 ppm.

      Inhalation, human.   Chloroform inhalation has a depressant effect
 on the  CNS,  with concentrations of 20,000 to 40,000 ppm used to induce
 anesthesia and  lower  concentrations to maintain it (NIOSH 1974,  Adriani
 1970, EPA 1985a).  According  to Goodman and  Oilman (1980),  a
 concentration of <1500 ppm is insufficient  to produce anesthesia;  1500
 to 2000 ppm  results in light anesthesia after induction;  and 2000  to
 15,000 ppm results in  deep anesthesia.  Chloroform anesthesia also
 sensitizes  the  heart  to  epinephrine,  causing arrhythmias  (Kurtz  et al
 1936, Orth et al.  1951,  EPA  1985a).  Delayed toxic effects  of chloroform
 after use  as an anesthetic included drowsiness,  restlessness, jaundice,
 vomiting,  fever, elevated pulse  rate,  liver enlargement,  abdominal
 tenderness, delirium,  coma,  and abnormal  liver and kidney  function
 (EPA 1980).

     Lehman and Hasegawa (1910)  and Lehman  and Schmidt-Kehl (1936)
 conducted  inhalation experiments with  humans  exposed to various
 chloroform concentrations  for up  to 30 min.  They reported  dizziness  and
 vertigo after exposure to  920 ppm  for  3 min,  and headache  and slight
 intoxication at higher concentrations.  No symptoms  were reported by
 subjects exposed to 390  ppm  for  30  min (EPA 1985a).  Exposures of <30
 minutes are insufficient to  achieve pulmonary steady state,  but  longer
 exposures to these concentrations might result in more  severe effects
 (EPA 1985a).

     Challen et al. (1958) investigated health effects of  occupational
 exposure to chloroform among  workers in a factory making medicinal
 lozenges containing chloroform. Nine of ten workers exposed to  -77 to
 237 ppm complained of tiredness, depression,  irritability,  thirst,
gastrointestinal distress, and frequent and burning urination.  Eight of
 ten workers exposed to 22 to  71 ppm experienced less  severe symptoms.
Both groups had been exposed  to occasional  peak concentrations  of  -1163
ppm for 1 to 2 min. None of  five controls experienced these symptoms.

-------
                                                 lexicological Data   55

     NIOSH  (1974) reported that a 33-year-old male who habitually
 Inhaled chloroform for 12 years experienced psychiatric and neurologic
 signs of depression,  loss of appetite, hallucination, ataxia, and
 dysarthria.

     Inhalation, animal.  EPA (1985a) summarized data concerning CNS
 effects of  chloroform inhalation in animals. In mice, 2500 ppm for 2 h
 caused no obvious effects; 3100 ppm for 1 h caused slight narcosis; and
 4000 ppm caused deep  narcosis in 30 min. Cats exposed to 7200 ppm
 experienced disturbed equilibrium after 5 min and narcosis as exposure
 duration increased.

     Oral,  human.  No data concerning human CNS effects of oral exposure
 to chloroform were located in the available literature.
     Oral,  animal.  Jones et al. (1958) reported that a single oral dose
 of 350 mg/kg was the  minimum narcotic dose for rats.
     Jorgenson and Rushbrook (1980) reported dose-related signs of
 depression  only during the first week of exposure in rats receiving oral
 chloroform  doses of 20 to 290 mg/kg/day for 90 days.
     Balster and Borzelleca (1982) found that gavage doses of 3.1 or
 31.1 /ig/kg/day chloroform had no effects on behavior of mice exposed for
 14 or 90 days. Administration of 100 or 400 mg/kg/day for 60 days
 affected operant behavior, but 100 mg/kg/day for 30 days did not affect
 learning.

     Dermal, human.   Dermal exposure may contribute to the CNS
 depression  observed in humans occupationally exposed to chloroform.
     Dermal, animal.   No animal data concerning CNS effects of dermally
 applied chloroform were located in the available literature.
     General discussion.   CNS effects of chloroform are well documented
 Harris and Groh (1985) found that the disordering effect of chloroform
 and other anesthetics on membrane lipids was enhanced by gangliosides.
 They suggested that this might explain why the outer leaflet of the
 lipid bilayer of neuronal membranes, which has a large ganglioside
 content,  is unusually sensitive to anesthetic agents. A study by Veiro
 and Hunt (1985) indicated that anesthetics inhibited membrane
 permeability independently of the channel system or type of lipid used,
 suggesting  that hydrogen-bonded water structure and/or hydrogen-bonding
 centers at dipolar lipid-polypeptide interfaces could be sites of action
 of general anesthetics.  Caldwell and Harris (1985) suggested that
 anesthetics affect calcium-dependent potassium conductance in the CNS.
 Some of these mechanisms may contribute to effects of chloroform on the
CNS.

4.3.3  Developmental  Toxicity

4.3.3.1  Inhalation

     Human.   No data  concerning human developmental effects of inhaled
chloroform were found in the available literature.

     Animal.  Schwetz et al.  (1974) found that chloroform was a
developmental toxicant in rats.  They exposed pregnant SD rats to 0, 30,

-------
 56   Section 4

 100,  or 300 ppm chloroform.  7  h/day,  on gestation  days 6  to  15.
 Increased incidences of missing ribs,  short or missing tail,  imperforate
 anus, subcutaneous edema,  and  delayed ossification of sternebrae
 occurred at 100 ppm. Subcutaneous  edema and abnormalities of the skull
 and sternum occurred at 300  ppm, but  their incidence was  not
 statistically significant, possibly because of the small  number of
 surviving fetuses (average of  4 per litter vs 10 per litter  for
 controls).  Exposure to 300 ppm also caused a decrease in  pregnancy rate,
 number of live fetuses per litter, and an increased percentage of
 litters with absorptions. Maternal weight gain was depressed at all
 doses.  Thus,  100 and 300 ppm are inhalation FELs,  and 30  ppm is a NOAEL
 for developmental toxicity in  rats. Dilley et al.  (1977), however,
 reported in abstract form  that exposure to 20 g/m^ (-4000 ppm) on days 7
 to 14 of gestation caused  increased fetal mortality and decreased fetal
 weight gain,  but no malformations  in  rats.
      Murray et al.  (1979) exposed  groups of 35 to  40 pregnant CF-1 mice
 to 100 ppm  chloroform for  7  h/day  on  days 1 to 7,  6 to 15 or 8 to 15 of
 gestation.  There was a significant increase in the number of resorptions
 per litter  in animals exposed  on days  1 to 7. Mean fetal body weight and
 crown to rump length were significantly decreased  in mice exposed on
 days  1  to 7 and 8 to 15. Maternal weight gain and  food and water
 consumption were depressed in  all  groups. Incidence of cleft palates was
 increased only in mice exposed on  days 8 to 15.

 4.3.3.2  Oral

      Human.   No data concerning human  developmental effects  of oral
 exposure to chloroform were  found  in  the available literature.
      Animal.   Thompson et al.  (1974) administered  oral doses of
 chloroform  to pregnant SD rats  on days 6 to 15 of  gestation  and to
 pregnant Dutch-Belted rabbits  on days  6 to 18 of gestation.  In the
 initial range - finding experiment with  rats, doses  of 0, 79,  126, 300,
 316,  or 516 mg/kg/day chloroform in corn oil were  used. Food consumption
 and body weight gains of dams were significantly decreased at >126
 mgAg/day.  One  of six rats at  316 mg/kg/day and four of six  rats at 516
 n»g/kg/day died and had pathologic  findings of acute toxic nephrosis and
 hepatitis.  Fetal development was affected only at  316 and 501 mg/kg/day
 where there was a significant  increase in resorption rate and a decrease
 in viable litter size and fetal body weights. No external abnormalities
 were  observed in surviving fetuses. In the main study, doses of 0, 20,
 50, or  126  mg/kg/day were administered to groups of 25 pregnant rats. No
 adverse effects occurred at  20 mg/kg/day, but maternal toxicity
 (decreased  body weight gains, mild fatty change in the liver) was
 evident at  i50  mg/kg/day, and  fetal body weights were significantly
 decreased in  the 126-mg/kg/day  group.  No treatment-related malformations
 were  seen at  any dose.  The significance of the decreased  fetal body
weights  at  126  mg/kg/day is debatable because the  decreases  occurred at
 a maternally  toxic  dose. In discussing the significance of such effects,
 EPA (1986b) stated  that "a change  in offspring body weight is a
 sensitive indicator of developmental toxicity," and that  "current
 information is  inadequate to assume that developmental effects at
maternally  toxic doses result only from the maternal toxicity." For

-------
                                                 lexicological Data   57

these reasons, it is not possible in this study to define a NOAEL and
LOAEL for developmental toxicity in rats.

     In the range-finding study with rabbits, doses of 0, 25, 63, 100,
159, 251, or 398 mg/kg/day were given to groups of five pregnant
rabbits. Maternal toxicity occurred at >63 mg/kg/day. In the main study,
groups of 15 pregnant rabbits were given 0, 20, 35, or 50-mg/kg/day.
Maternal weight gain was depressed at 50 mg/kg/day, and mean fetal body
weight was depressed at 20 and 50 but not 35 mg/kg/day. No teratogenic
effects were observed. Incidence of incompletely ossified skull bones
was significantly increased among fetuses, but not litters, at 20 and 35
mg/kg/day but not at 50 mg/kg/day. Because the incidences of incomplete
ossification were not dose related,  and because the incidences using the
litter rather than the fetus as the unit of comparison were not
statistically significant, the 50-mg/kg/day dose can be considered a
NOAEL for developmental toxicity in rabbits.

     Balster and Borzelleca (1982) administered 31.1 mg/kg/day
chloroform in drinking water to pregnant mice throughout gestation and
lactation. No behavioral effects were observed in offspring. Burkhalter
and Balster (1979) administered gavage doses of 31.1 mg/kg/day to adult
ICR mice from 21 days prior to mating until day 21 after birth and to
the pups from days 7 to 21 after birth.  Weight gain of pups exposed on
days 7 to 21 after birth was reduced. No significant adverse behavioral
effects were noted.

4.3.3.3  Dermal

     Human.   No data concerning human developmental effects of dermal
exposure to chloroform were found in the available literature.

     Animal.  No data concerning animal developmental effects of dermal
exposure to chloroform were found in the available literature.

4.3.3.4  General discussion

     Developmental toxicity studies of inhaled and orally administered
chloroform in animals indicate that chloroform is toxic to dams and
fetuses. Chloroform has been shown to cross the placental barrier in
mice.  Danielsson et al. (1986) found volatile radioactivity in the
placenta and fetuses of pregnant mice a short time after inhalation of
^C-chloroform.  Chloroform metabolites accumulated with time, especially
in the amniotic fluid. In early gestation, metabolites accumulated in
embryonic neural tissues;  in late gestation, accumulation occurred in
the fetal respiratory epithelium. Although data regarding developmental
effects of chloroform in humans were not available, there is no reason
to believe that chloroform would not cross the placental barrier in
humans.

4.3.4  Reproductive Toxicity

4.3.4.1  Inhalation

     Human.   No data concerning human reproductive effects of inhaled
chloroform were found in the available literature.

-------
 58   Section 6
      Animal.   Land et al.  (1981)  exposed male mice to atmospheric
 chloroform concentrations  of 0.04 or 0.08%  (400 or 800 ppm), 4 h/day for
 5 days.  Both  concentrations  caused significant increases  in  the
 percentage of abnormal sperm.  Intraperitoneal injection of male mice
 with chloroform in corn oil  at 0.025 to 0.25 mg/kg/day for 5 days did
 not result in increased incidences of sperm head abnormalities (Topham
 1980).

 4.3.4.2   Oral

      Human.   No data concerning human reproductive effects of oral
 exposure to chloroform were  found in the available literature.

      Animal.   As previously  described, Palmer et al. (1979) administered
 gavage doses  of 0.  15,  30, 150, or 410 mg/kg/day in toothpaste, 6
 days/week to  SD rats (10/sex/group) for 13 weeks. One of  the
 histological  effects observed  in  high-dose rats was gonadal atrophy.

 4.3.4.3   Dermal

      No  data  concerning human  or  animal reproductive effects of dermal
 exposure to chloroform were  found in the available literature.

 4.3.4.4   General discussion

      There was little useful  information concerning the reproductive
 effects  of chloroform.

 4.3.5  Genotoxicity

 4.3.5.1   Human

     Mixed results were obtained  in sister chromatid exchange assays in
 cultured human lympohocytes  (Table  4.1). No other genotoxicity studies
 in humans in  vitro or in vivo were  found.

 4.3.5.2   Nonhuman

     Studies  on the  in vitro genotoxicity of chloroform in prokaryotes,
 eukaryotes, and cultured mammalian cells are summarized in Table 4.1.
 Results  of tests  for gene mutation have been negative in  prokaryotes and
 mixed in yeasts.  Chloroform did not produce gene mutations or chromosome
 aberrations in hamster  cells.

     Studies  of the  in  vivo genotoxicity of chloroform are summarized  in
Table 4.2. Tests  for gene mutations in DrosophLla and for DNA damage in
 rats and mice were negative, whereas tests for chromosome aberrations
 and sperm abnormalities were mixed.

 4.3.5.3  General  discussion

     The EPA  (1985a)  summarized studies concerning binding of
metabolically activated chloroform to liver microsomal and nuclear
protein  and lipid. They concluded that DNA binding of metabolically
activated chloroform occurs only  to a limited degree, if  at  all.

-------
                                      Table 4.1.  Genoloxicity of chloroform in vitro
       End point
Gene mutation
DNA damage
                              Species (test system)
            Result
with activation/without activation
         Reference
                         Salmonella typhimurium
                         Escherichia coli
                         Yeast
                         Saccharomyces cerevisiae and
                         Schizosaccharomyces pombe
                         Saccharomyces cerevisiae
                         Chinese hamster lung fibroblasts

Chromosome aberrations   Chinese hamster ovary cells
Cytogenetics              Human lymphocytes
           — /mixed


           NT/+fl
           NT/-

           -/NT
           — /mixed
Van Abbe et al. 1982.
Simmon et al.  1977,
Uehleke et al.  1977.
Gockeetal.  1981,
de Serres and Ashby 1981.
and other studies reviewed
by  EPA !98Sa and
Rosenthal 1987

Kirkland et al. 1981.
dc Serres and Ashby 1981.
Reitz et al. 1982


Callen et al.  1980
de Serres and Ashby 1981
Reitz et al. 1982

Callen et al.  1980

Sturrock 1977

White et al. 1979

Kirkland et al. 1981.
Morimoto and Koizumi 1983
   "NT = not tested.
                                                                                                                               o
                                                                                                                               o
                                                                                                                              o
                                                                                                                              to
                                                                                                                              fii
                                                                                                                              n
                                                                                                                              to

-------
 60    Section  6
                       Table 4.2.  Genotoxicity of chloroform in vivo
       End point
  Species (test system)     Result
                 References
Gene mutation


Chromosome aberrations
Cytogenetic
Sperm abnormalities
DNA damage
Drosophila melanogaster   —
Grasshopper embryos
Mouse bone marrow
Mouse



Rat hepatocytes
Mouse
         Gockeet al. 1981,
         deSerresand Ashby 1981
+       Liang et al. 1983

Mixed    Morimoto and Koizumi 1983,
         de Serres and Ashby 1981,
         Gockeet al. 1981,
         Agustin and Lim-Sylianco
         1978

Mixed    Topham 1980,
         Landetal. 1981,
         de Serres and Ashby 1981
—       Mirsahset  al. 1982
—       Reitz et ai. 1980

-------
                                                 Toxicological Daca   61

     While bacterial mutagenicity tests with chloroform were
predominantly negative, false negative results could have been obtained
because of (1) activation systems inadequate to metabolize chloroform co
a reactive compound, (2) instability and reactivity of phosgene so thac
it may have been scavenged by microsomal protein or lipid before it
could reach the bacterial DNA, and (3) volatility of chloroform that may
have led to inadequate exposure of the bacteria (EPA 1985a; Rosenthal
1987). In addition, a report on the EPA Gene-Tox Program (Kier et al
1986) stated that compounds having complex metabolic pathways, such as
halogenated hydrocarbons, often give false negative results in the
Salmone.Ha/microsome assay.  Additional studies are needed before
chloroform could be considered mutagenic in yeast.

     Tests for chromosome aberrations, such as sister chromatid
exchange, caused by chloroform in various systems have resulted in mixed
results. Many of these studies are inadequate, and additional studies
may be needed.

     The available evidence concerning DNA damage,  binding to
macromolecules and mitotic arrest, suggests that chloroform may be
mutagenic, but no definitive conclusion can be reached concerning
mutagenicity of chloroform. The study by Land et al. (1981) reported
significantly increased percentages of abnormal sperm in mice exposed by
inhalation (see Sect. 4.3.4), indicating that chloroform can gain access
to germinal tissue and may pose a mutagenic risk.

4.3.6  Carcinogenicity

4.3.6.1  Inhalation

     Data concerning careinogenieity of inhaled chloroform in humans or
animals were not found in the available literature.

4.3.6.2  Oral

     Human.  Numerous epidemiologic studies of the relationship between
cancer incidence and various components of drinking water, including
chloroform, have been reviewed (EPA 1980, 1985a; NAS 1977). An
association between cancer of the large intestine,  rectum, and/or
bladder and the constituents of chlorinated drinking water was evident
in many of these studies. Chloroform has not been identified as the sole
or primary cause of excess cancer rates, but it is one of several
volatile organic contaminants, many of which are considered to have
carcinogenic potential, found in drinking water. Several of the earlier
epidemiologic studies suffered from (1) lack of measured chloroform
concentrations in drinking water; (2) lack of data concerning
concentrations of other organics; (3) limited information concerning
personal drinking water consumption; (4) long latency periods; and  (5)
effects of migration, making it difficult to quantify exposure (EPA
198Sa).

     Host of the available studies are ecological in nature, but, more
recently, some case-control studies have been published. Most of  the
ecological studies tend to support a weak but significant  association
between risks of bladder, colon, and rectal cancer and water
chlorination. The odds and risk ratios calculated in the case-control

-------
 62   Section 4

 studies were as high as 3.6 (Young et al.  1981)  but were generally
 between 1.1 and 2.0 and could be explained by confounding effects  such
 as diet, smoking, and occupation.  The association appears to be fairly
 consistent, however, across several independent  and diverse study
 groups. Although it can be concluded that  the human data suggest a
 possible increased risk of cancer  at these three sites  (from exposure to
 chloroform in chlorinated drinking water)  because chloroform is the
 predominant trihalomethane in drinking water,  the data  are too weak  to
 draw a conclusion about the carcinogenic potential of chloroform (EPA
 1985a).

      Animal.   The key carcinogencity studies  EPA (1985a)  considered  for
 the derivation of the carcinogenic potency factor are the NCI (1976)
 bioassay in rats and mice,  a study by Roe  et  al.  (1979)  in several
 strains of mice, and a study by Jorgenson  et  al.  (1985)  in rats and
 mice.

      NCI (1976)  administered gavage doses  of  chloroform in corn oil  to
 B6C3F1 mice (50/sex/group)  5 days/week for 78  weeks  followed by 14 to 15
 weeks  of observation.  The chloroform used  in  this study was USP grade,
 which  is >99.0%  chloroform and 0.5 to 1.0% ethanol.  Initial dosages  were
 100 and 200 mg/kg for males and 200 and 400 mg/kg for females.  These
 levels were increased after 18 weeks to 150 and  300  mg/kg for males  and
 250 and 500 mg/kg for females.  Time-weighted  average (TWA)  dosages were
 138 and 277 mg/kg for males and 238 and 477 mg/kg for females.  There was
 a  statistically  significant dose-related increase in hepatocellular
 carcinomas  in  both sexes  (females--0/20 controls,  36/45  low dose,  and
 39/41  high  dose,  males--1/18 controls,  18/50  low dose,  and 44/45 high
 dose).

     NCI  (1976)  administered gavage doses  of  chloroform in corn oil  to
 Osborne-Mendel rats  (50/sex/group)  5 days/week for 78 weeks followed by
 a  33-week observation period.  Treated male  rats  received 90 or 180
 mg/kg.  Treated females initially received  125  and 250 mg/kg,  but these
 doses  were  reduced to  90  and 180 mg/kg after  22  weeks and resulted in
 TWA doses of 100 and 200  mg/kg administered 5  days/week.  There was a
 statistically  significant dose-related trend  in  incidence of kidney
 epithelial  tumors  in male rats  (0/99 controls, 4/50  low dose,  12/50  high
 dose).

     Roe et al.  (1979) administered gavage  doses  of  chloroform in
 toothpaste  to four strains  of mice  (C57BL,  CBA,  CF/1, and ICI)  in  three
 different experiments. Chloroform was  administered 6 days/week for 80
 weeks  followed by  a  13- to  24-week  observation period.  In one study,
 groups  of 52 male  and  52  female ICI  mice received 17 or  60 mg/kg/day in
 toothpaste. A group  of 100  mice per  sex served as controls.  In a second
 study,  groups of 52  male  ICI mice  received toothpaste containing 0 or 60
 rag/kg/day.  In the  third study,  groups  of 52 male  mice of strains C57CL,
 CBA. CF/1,  and ICI received 0 or 60  mgAg/day  in toothpaste or arachis
 oil. In males of  the C57BL,  CBA, and CF/1  strains, there  were no
 treatment-related  effects on incidence  of  any  type of tumors.  There  was
a significantly  increased incidence  of moderate  to severe kidney
 "changes" in male  CBA  and CF/1 mice. Male  (but not female)  ICI mice
experienced an increase in  epithelial  tumors of  the  kidney at a dose of
60 mgAg/day (8/38)  [but  not at 17  mgAg/day  (0/37)) relative to

-------
                                                 lexicological Data   63

controls (0/72) when chloroform was administered in toothpaste. A more
pronounced increase in kidney tumor incidence was seen in male mice
given 60 mg/kg/day in arachis oil (12/48 treated vs 1/50 vehicle
controls). The incidence of malignant kidney tumors in these mice was
0/50 in controls and 9/48 in the 60 mgAg/da7 group.
     Jorgenson et al.  (1985) administered 0, 200, 400, 900, and 1800
mg/L chloroform in the drinking water of male Osborne-Mendel rats (50 to
330/group) and female B6C3F1 mice (50 to 430/group) for 104 weeks. There
was also a matched control group of 50 animals whose water intake was
restricted to that of the high-dose group for each species. Group sizes
were adjusted to detect a tumor response at low doses, assuming that
there was a linear relationship between tumor incidence and dose. The
low-dose groups therefore had larger numbers of animals. The chloroform
used in this study was pesticide-quality chloroform that had been
distilled to remove diethylcarbonate. Water consumption of rats and mice
was decreased in a dose-related manner. TWA chloroform dosages reported
by the authors were 0, 19, 38,  81,  and 160 mg/kg/day for rats and 0, 34,
65, 130, and 263 mg/kg/day for mice. There were treatment-related
increases in several types of tumors (including renal tumors) in male
rats. However, only the statistically significant increase in incidence
of renal tumors was clearly dose related. Incidences of renal tubular
cell adenomas and/or adenocarcinomas were as follows: 4/301 in controls,
4/313 at 19 mg/kg. 4/148 at 38 mg/kg, 3/48 at 81 mgAg, and 7/50 at 160
mg/kg.  The incidence in high-dose male rats was similar to but slightly
lower than that observed in the NCI (1976) corn oil gavage study with
rats of the same strain. Body weight gains were depressed in a dose-
related manner as a result of decreased water and, presumably, food
consumption.  Survival was inversely related to chloroform dosage. This
effect was attributed to the increased chloroform dosages being
associated with leaner animals, as indicated by the fact that control
rats on the restricted water intake survived much better than normal
controls.

     In mice, a subgroup of treated animals refused to drink water
containing chloroform, resulting in 25% mortality in the two highest -
dose groups during the first 2 weeks of the study. In contrast to the
NCI (1976) mouse study, there was no treatment-related increase in
hepatocellular adenomas and carcinomas in female B6C3F1 mice. No
treatment-related hepatic or renal tumors were found in mice. Jorgenson
et al.  (1985) felt that this difference might be due to some interaction
of chloroform with the corn oil vehicle in the NCI (1976) study.

     Jorgenson et al.  (1985) discussed possible explanations for  the
different mouse liver-tumor responses in their study and the NCI  (1976)
study.  They speculated that either the dosing schedule  (bolus gavage
dose vs gradual administration in drinking water) or the vehicle  (corn
oil vs drinking water) may have caused the differences. These authors
noted a study by Newbeme et al. (1979) in which corn oil  in the  diet
increased the number of liver tumors in aflatoxin BI-initiated rats.  If
some background level of spontaneously initiated cells  is assumed to
occur in B6C3F1 mice,  then a chloroform-corn oil interaction might  cause
the increased tumor yield. This possibility was supported by Newberne  ec
al. (1982), who found that partial hepatectomy increased liver tumors  in
B6C3F1 mice.  Jorgenson et al. (1985) also noted that the historical

-------
 64   Section 4

 incidence of liver tumors was consistent with the incidence  observed in
 their study, and that this incidence had not varied between  vehicle
 control animals given corn oil by gavage compared with dietary
 administration. This indicated that the  positive  response  in the  NCI
 (1976) study could not be attributed to  corn oil  alone.  Jorgenson et al.
 (1985) suggested that corn oil may hasten the expression of  chloroform-
 initiated cells in the livers of B6C3F1  mice,  or  chloroform  may
 interfere with the normal lipid metabolism of the liver.

      Pereira et al. (1985) found that chloroform  administered in
 drinking water appeared to inhibit the development of  hepatic tumors Ln
 CD-I Swiss mice that had been pretreated with ethylnitrosourea. These
 authors speculated that the difference between their results and  the NCI
 (1976) mouse study may have been caused  by the administration of
 chloroform as a bolus in the NCI (1976)  study or  that  there  may have
 been some interaction between chloroform and corn oil  in the NCI  (1976)
 study. Moore et al. (1982) also found that regenerative  changes and
 toxic effects on liver and kidneys of CFLP outbred Swiss albino mice
 were greater when chloroform was administered in  corn  oil  rather  than  in
 a  toothpaste base.

      Bull et al.  (1986)  investigated possible  vehicle  effects on
 chloroform toxicity in male and female- B6C3F1  mice.  Mice were
 administered chloroform by gavage in corn oil  or  water at  doses of 0
 60,  130,  or 270 mg/kg/day for 91 to 94 days.  The  chloroform/water
 mixtures  were 2%  emulphor,  an emulsifying agent used to  produce aqueous
 emulsions of hydrophobic chemicals.  As detailed in Sect. 4.3.2.1,
 chloroform in corn oil was more  hepatotoxic  than  chloroform  in emulphor
 and  more  toxic  than chloroform administered  in drinking water in  another
 study (e.g.,  Jorgenson et al.  1985).  These results indicated that the
 difference in incidence  of mouse liver tumors  between  the  NCI (1976) and
 Jorgenson et al.  (1985)  studies  was  due  to the corn oil vehicle,  with
 chloroform being  more  hepatotoxic  when administered in corn  oil than in
 water. Because  the  Withey et  al.  (1983)  study  showed that  the use of a
 corn oil  vehicle  actually decreased the  rate and  extent of chloroform
 absorption from the gastrointestinal  tract.  Bull  et al.  (1986)  concluded
 that it was  unlikely that the  differences  in carcinogenic  response could
 be attributed to  pharmacokinetic  effects. Bull et al.  (1986)  proposed
 that some  interaction  between  the  vehicle and  chloroform might cause the
 difference  in carcinogenicity, particularly  if the carcinogenic response
 in mouse  liver  is secondary to  the hepatoxicity of chloroform.

      Data  from  these and other  long-term  oral  carcinogenicity studies of
 chloroform are  summarized in Table 4.3.

 4.3.6.3  Dermal

     No data  concerning  carcinogenicity of dermal  exposure to chloroform
 in humans  or  animals were  found  in  the available  literature.

4.3.6.4  General discussion

     On the basis of data  showing  specific carcinogenic activity  in
kidneys and liver of mice  and rats, EPA  (1985a) concluded  that there was
sufficient evidence for  carcinogenicity of chloroform  in experimental
animals using the EPA weight-of-evidence criteria.  The EPA (1985a) also

-------
                                           Table 4.3. Oral cucinogcnicily studies of chloroform
       Animali
Sprague-Oawley rals




Wislar rais



B6C3FI mice


Strain A mice



Beagle dogs


Osborne-Mendel rals
                 Exposure
Osborne-Mendel
male rals
0. IS. 75. or 165 mg/kg/day in toothpaste
6 days/week for 52 weeks, or 0 or 60
mg/kg in toothpaste 6 days/week for
80 weeks

2900 ppm in drinking water for 72 weeks.
then I4SO ppm  for remainder of lifetime


0. 600. or  1800  ppm in drinking water
for 52 weeks

0. ISO. 300. 600. 1200. or 2400 mg/kg
by gavagc in olive oil once every 4 days
for 30 dose*

0. 15, or 30 mg/kg/day in capsules
6 days/week for 7 years

TWA dosages of 0. 90. and 180 mg/kg/day
(males) and 0. 100. and 200 mg/kg/day
(females) S days/week by gavage in corn
oil for 78 weeks followed by 33 weeks
of observation

0. 200. 400. 900. and 1800 mg/L in
drinking water for 104 weeks
            Response
                                                                                                                 References
No carcinogenic response
Increased incidences of neoplasiic
nodules and hepatic adenofibrosis
compared with control*

No carcinogenic response
Hepalomas in females at 600 and
1200 mg/kg


No carcinogenic response


Increased incidence of kidney
epithelial tumors in males
Palmer el al 1979




Tumasoniset al  I98S



Klaumgetal 1986


Eschenbrenner and Miller I945a



Hey wood el al 1979


NCI  1976
Increased incidence of renal tumors    Jorgenson el al 198$
                                                                                                                                                         5*
                                                                                                                                                         o
                                                                                                                                                         n>
                                                                                                                                                         o
                                                                                                                                                         to
                                                                                                                                                         r»
                                                                                                                                                         ft)

-------
       Animals
B6C3FI mice
C57BI, CBA. andCF/l
male mice


ICI mice
NIC mice
                                                         Table 4.3  (continued)
                                                                                                                                 in
                                                                                                                                 CD
                                                                                                                                 n
                                                                                                                                 ri
                                                                                                                                 f-.
                                                                                                                                 §
                                         Exposure
TWA dosages of 0. 138. and 271 mg/kg/day
(males) and 0. 138. and 477 mg/kg/day
(females) S days/week by gavagc in corn
oil for 78 weeks followed by 14 to IS weeks
of observation
0. 200. 400. 900. 1800 mg/L in drinking
water for 104 weeks

0 or 60 mg/kg/day 6 days/week by gavage
in toothpaste or arachis oil for 80 weeks
followed  by  13 to 24 weeks of observation
0, 17. or 60 mg/kg/day 6 days/week by
gavage in toothpaste or arachis oil for
80 weeks followed by 13 to 24 weeks of
observation

0 I mL of 40% chloroform in oil by
gavage twice weekly for an unspecified
period
                                                        Response
                                                                    Increased incidences of hcpalo-
                                                                    ccllular carcinomas in males and
                                                                    females
No increase in liver tumors


No treatment-related effects on
tumor incidence


Increased incidences of epithelial
kidney tumors in males given 60
mg/kg/day in toothpaste or oil


Hepalomas and hepatic lesions in
three of five mice examined
                                                                                                                 References
NCI 1976





Jorgenson el al  1985

Roe ct al 1979



Roeetal 1979




Rudah 1967

-------
                                                 Toxicologies! Data   67

 concluded that the epidemlological evidence for chloroform
 carcinogenicity was Inadequate. Overall, EPA (1985a) placed chloroform
 In Group B2, meaning that it is considered a probable human carcinogen.
 IARC  (1979, 1982) has classified chloroform in Group 2B.

      The recent study by Jorgenson et al. (1985) confirmed the
 carcinogenicity of chloroform in producing renal tumors in male
 Osborne-Mendel rats, as was observed in the NCI (1976) study. The
 primary tumors were of tubular cell origin and occurred at comparable
 times in the two studies. Roe et al. (1979) also observed an increase in
 renal tumors in ICI mice.

      The available data concerning mouse liver tumors are conflicting.
 The Jorgenson et al. (1985) drinking water study failed to produce an
 increased tumor incidence in livers of female B6C3F1 mice, in contrast
 to the NCI (1976) corn oil gavage study. The negative result is
 consistent with the absence of liver tumor effects in four strains of
 mice  tested by Roe et al. (1979), in which chloroform was administered
 in a  toothpaste base.  A pharmacokinetic study by Uithey et al. (1983)
 indicated that chloroform was absorbed more slowly and to a lesser
 extent from corn oil than from water, suggesting that pharmacokinetic
 effects are not responsible for the differences in liver tumor
 responses.  Historical control data cited by Jorgenson et al. (1985)
 indicated that corn oil alone is not responsible for the increased
 incidence of liver tumors. Jorgenson et al. (1985) and Bull et al.
 (1986) concluded that the corn oil vehicle effect on mouse liver tumors
 may be due to some interaction between the vehicle and chloroform.
 Another possible explanation for the discrepancy is the difference in
 dosing schedule (bolus gavage doses vs gradual dosing in drinking
 water).  Bolus administration would result in higher-peak blood levels
 than gradual drinking water administration of the same dosage. The EPA
 (1985a)  stated, however,  that virtually all of the chloroform
 administered in drinking water would be absorbed and metabolized to
 reactive metabolites,  but a certain percentage of a bolus gavage dose
 would be excreted unchanged. Using the available pharmacokinetic data,
 EPA (1985a)  estimated that for rats and mice given 60 mg/kg by gavage,
 the amount of the dose excreted unchanged would be 6% for mice and 20%
 for rats.  In drinking water administration, virtually all of the dose is
metabolized.

     A study by Capel et al. (1979) indicated that chloroform (0.15 or
 15 mg/kg/day administered in drinking water for 14 days) could enhance
 the growth of three types of murine tumors in mice.

     Demi and Oesterle (1985) investigated the promoting activity of
chloroform.  Chloroform at doses of 100 to 400 mg/kg administered twice
weekly for 11 weeks caused a dose-related increase in the number of
preneoplastic foci in livers of rats that had been given a single dose
of diethylnitrosamine.  Doses of 25 mg/kg had no promoting effect. Doses
of 200 or 400 nig/kg/day for 33 days or 800 mg/kg for 20 days did not
cause formation of preneoplastic foci. These results indicated that
chloroform had promoting rather than initiating activity, although the
 initiating potential of chloroform was not adequately assessed in this

-------
 68   Section 4

 study. A similar study by Pereira et al.  (1982)  did not detect any
 tumor-initiating activity of chloroform,  and the results concerning  its
 promoting activity were inconclusive.

      Reltz et al. (1980, 1982) investigated the  possible mechanisms  of
 chloroform carcinogenicity.  They found that chloroform doses  (single
 oral doses of 60 and 240 mg/kg)  that resulted in increased tumor
 incidences in male B6C3F1 mice also caused severe necrosis at liver  and
 kidney sites prior to tumor  development.  A chloroform dose (15 mg/kg)
 that did not result in increased tumor incidence also did not cause
 necrosis and regeneration. In vivo studies of DNA alkylation  and  repair
 did not indicate any genotoxic effects of chloroform.  The authors
 suggested that the mechanism of chloroform carcinogenesis was nongenetic
 and that noncytotoxic doses  should pose no carcinogenic  risk.

 4.4  INTERACTIONS WITH OTHER CHEMICALS

      The EPA (1985a)  noted that  chloroform toxicity is influenced by
 anything that alters  microsomal  enzyme activity  or hepatic GSH levels.

      Sato and NakaJima (1984)  reviewed data concerning effects of diet
 and ethanol  on chloroform metabolism and  toxicity.  They  concluded that
 food deprivation causes a twofold to threefold increase  in hepatic
 metabolism of chloroform.  The  cause of this  effect is  the lack of
 carbohydrate,  a high  level of  which represses  the  hepatic metabolism of
 volatile hydrocarbons.  Ethanol was  found  to  increase  the hepatic
 metabolism of chloroform.

      Kutob and Plaa  (1962) studied  interactions  of 1  to  15 daily  oral
 ethanol  doses  in mice followed by subcutaneous injections of  chloroform
 at  various times after treatment. They found that  the  two chemicals
 given together  caused histological  changes  in  livers  that did not occur
 with either  chemical  alone.  They also  found  that ethanol pretreatment
 significantly  increased the  concentration of chloroform  in the liver. A
 single dose  of  ethanol  was as  effective as multiple doses.  The authors
 proposed that ethanol increased  the  lipid content  of  the liver
 (increased liver triglyceride  content  was observed), which results in
 increased concentrations  of  chloroform to be metabolized in the liver. A
 similar  result was reported  by Danni et al.  (1981), who  found that oral
 isopr-panol  pretreatment  followed by chloroform  inhalation caused severe
 fatty  infiltration of the liver  and chloroform alone  increased liver
 triglycerides.

      Sato  et al.  (1980,  1981)  studied  the  in vitro metabolism of
chloroform by liver microsomal enzyme  systems from rats  pretreated with
ethanol  In drinking water. Their results indicated that  ethanol was  both
a stimulator and inhibitor of  microsomal enzymes, depending on how much
remained  in  the  body  and how much time elapsed since  ingestion.

     Kluwe and Hook (1978) reported that PBBs administered in the diets
of mice potentiated the hepatic  and renal toxicity of  intraperitoneally
injected chloroform.  This effect was assumed to be due to enhanced
chloroform metabolism resulting  from PBB Induction of microsomal
enzymes.

-------
                                                 lexicological Data   69

     Various ketones and ketogenic substances have been found to
potentiate chloroform toxicity.  Hewitt et al. (1979) and Cianflone et
al. (1980) found that chlorodecone pretreatment increased hepatotoxicity
of chloroform but that the nonketonic structural analog, mirex, did not
Hewitt et al. (1980) found that  other ketones also enhanced hepatic and
renal toxicity of chloroform in  rats, with methyl-n-butyl ketone (MBK)
and 2,4-hexandione the most potent,  followed by acetone and n-hexane (a
ketogenic chemical) (EPA 1985a).  Hewitt et al.  (1983) found a positive
correlation between ketone carbon chain length (3C to 7C) and the
severity of potentiated chloroform hepatotoxicity in rats. The ketones
themselves were not hepatotoxic  at those doses. Branchflower and Pohl
(1981) proposed that MBK potentiated chloroform hepatotoxicity by
increasing cytochrome P450 levels (thereby enhancing chloroform
metabolism to phosgene) and by decreasing GSH levels.
     Disulfiram, an inhibitor of microsomal drug-metabolizing enzymes,
decreases the hepatotoxicity of  chloroform (Scholler 1970, Masuda and
Nakayama 1982).  Diethyldithiocarbamate and carbon disulfide pretreatment
also protect against chloroform  hepatotoxicity (Masuda and Nakayama
1982,  1983; Gopinath and Ford 1975), presumably by inhibiting drug-
metabolizing enzymes.

-------
                                                                      71
               5.  MANUFACTURE, IMPORT, USE, AND DISPOSAL

 5.1   OVERVIEW

      Chloroform  is produced at six locations in Che United States
 primarily by the chlorination of methyl chloride resulting from the
 reaction of methanol and hydrogen chloride. Of the chloroform produced,
 93%  is used to make fluorocarbon-22.  The remainder is either exported or
 used as a solvent, fumigant, dry cleaning spot remover, intermediate in
 the  preparation of dyes and pesticides, and in fire extinguishers.

 5.2   PRODUCTION

      During 1985, 275.3 million pounds of chloroform were produced
 (USITC 1986). Mild summer weather in 1985 caused a decrease in the
 demand for air conditioner maintenance and new air conditioners.
 Consequently, the output of both fluorocarbon-22 refrigerant and
 chloroform was lower in 1985 than in previous years (CMR 1986a).

      Manufacturers and sites of chloroform production are as follows:
 Occidental Petroleum Corp., Belle, West Virginia; Dow Chemical,
 Freeport, Texas, and Plaquemine, Louisiana; LCP Chemicals, Moundsville,
 West  Virginia;  and Vulcan Chemicals,  Geismar, Louisiana, and Wichita.
 Kansas (SRI 1987). Dupont was scheduled to complete a conversion project
 at its Corpus Christi,  Texas, plant during 1986 that would add 300
 million pounds to its annual chloroform production capacity (CMR 1986a)
 Stauffer Chemical is reported to have 72 million pounds per year of idle
 capacity at its Louisville, Kentucky, plant (CMR 1986a).

      There are two common methods for commercially producing chloroform-
 chlorination of methane or chlorination of methyl chloride produced by
 the reaction of methanol and hydrogen chloride (Alhstrom and Steele
 1979, DeShon 1979).  The methanol process accounts for -92% of the
 production capacity, and the methane process accounted  for only 8% (SRI
 1987).

 5.3   IMPORT

      It appears that chloroform is currently imported into the United
 States. Chemical Marketing Reporter (CMR 1986b) indicates that
 2,314,851 Ib of chloroform were imported into the United States in
 February 1985.

 5.4  USES

     The use pattern for chloroform is as follows (CMR  1986):
 fluorocarbon-22 (F-22), 93% (refrigerants, 52%; fluoropolymers, 41%);
miscellaneous,  4%; and exports, 3%.  Miscellaneous uses  include use as an
extraction solvent and a solvent for penicillin, alkaloids, vitamins,

-------
 72   Section 5

 flavors, lacquers,  floor polishes, artificial silk manufacture, resins,
 fats, greases, gums, waxes, adhesives, oils and rubber, and a dry
 cleaning spot remover;  in fire extinguishers; as an intermediate in the
 preparation of dyes and pesticides; and as fumigants (DeShon 1979).

     Chloroform was formerly used as an anesthetic but was replaced by
 safer and more versatile materials (DeShon 1979). The U.S. Food and Drug
 Administration banned the use of chloroform in drug, cosmetic, and food
 packaging products  in 1976 (Windholz 1983). This ruling does not include
 drug products that contain chloroform in residual amounts from its use
 as a processing solvent in manufacture or as a by-product from the
 synthesis of drug ingredients (IARC 1979).

 5. 5  DISPOSAL

     The EPA requires that persons who generate, transport, treat,
 store,  or dispose of this compound comply with regulations of the
 federal Resource Conservation and Recovery Act (RCRA).  One method of
disposing of chloroform involves sedimentation followed by dual-media
 filtration and adsorption onto activated carbon at 10 to 100 Ib/lb
soluble material (EPA-NIH 1987).

-------
                                                                     73
                         6.   ENVIRONMENTAL FATE

6.1  OVERVIEW
     When released to the atmosphere,  chloroform may be  transported Long
distances before ultimately being degraded by reaction with
photochemically generated hydroxyl radicals (half-life of -3  months).
Significant amounts of this compound may be removed from the  atmosphere
in precipitation; however, most chloroform removed by this mechanism is
likely to reenter the atmosphere by volatilization.  When released into
water, volatilization is the primary fate process (half-life  of 1-31
days). When released to soil, chloroform will either volatilize rapidly
from the surface or leach readily through soil, ultimately entering
groundwater. It is predicted to persist for relatively long periods of
time in groundwater.

6.2  RELEASES TO THE ENVIRONMENT
     As reported by Rehm et al. (1982), the major sources of
anthropogenic release of chloroform to the environment are listed in
Table 6.1. It is assumed that essentially all of the indirectly produced
chloroform would be emitted into the environment. Indirect sources
include bleaching of pulp by pulp and paper mills, drinking water
chlorination, ethylene dichloride manufacture, trichloroethylene
photodegradation, municipal wastewater chlorination, cooling water
chlorination, and automobile exhaust (EPA 1985a,c). Pulp and paper mills
emit more chloroform to the environment than any other single source
Other indirect sources of chloroform that could not be quantified are
chlorination of textile wastewater, the food processing  industry,
breweries, combustion of tobacco products treated with chlorinated
pesticides, thermal decomposition of plastics, biological production  of
marine algae, and the reaction of chlorinated pollutants with humic
materials in natural waters  (EPA 1985a).

6.3  ENVIRONMENTAL FATE

6.3.1  Air
     Based on a vapor pressure of  159 mm Hg  at  20°C,  chloroform  is
expected  to exist almost entirely  in the vapor  phase  in  the  atmosphere
(Boublik  et al.  1984, Eisenreich et al.  1981).  Chloroform has  a  rather
low partition coefficient between  air and water (H  -  0.125), which
indicates that significant  amounts of  this compound may  be removed from
the atmosphere in wet deposition  (Nicholson  et  al.  1984).  Nevertheless,
most of the chloroform  removed from air in precipitation is  likely to
reenter the atmosphere  by volatilization.

-------

Environmental release (metric
Source
Pulp and paper milli (from the
bleaching of pulp)
Drinking water chlonnalion
Pharmaceutical manufacture
Eihylenc dichlonde manufacture
Tnchloroethylenc photodegradalion
Municipal waitewaler chlonnalion
Cooling water chlonnalion
Mclbyl chloride chlonnalion
Automobile eihauit
Chlorodifluoromethanc manufacture
Loading and traniil losses
Methane chlonnalion
Hypaloo* manufacture
Grain fumigation
Secondary product contamination
Laboratory usage
Total
"Value* are rounded.
Minor releases nossible.
Air
4113
0
570
760
780
0
190
196
180
139
901
70.2
549
28.4
9.8
c
71814


Percent of total*
39
0
5.5
73
75
0
18
19
17
13
09
0.7
OS
0.3
0.1
c
688


Water
298
1.900
46
6
0
320
72
8
0
b
0
33
b
0
06
c
26479


Percent of total*
29
18
04
b
0
31
07
01
0
b
0
003
b
0
0006
c
254


Land
0
0
384
217
0
0
0
54
0
2
0
b
b
0
02
c
6086


tons/year)
Percent of total*
0
0
3.7
21
0
0
0
01
0
002
0
b
b
0
0002
c
58



Total
4.411
1.900
1.000
977
780
320
262
2094
180
141
901
735
549
284
106
c
10.4382"



Percent of total*
42
18
10
94
75
31
25
20
17
14
09
07
05
03
01
c



                                                                                                                                                           (0
                                                                                                                                                           A
                                                                                                                                                           n
                                                                                                                                                           it
                                                                                                                                                           K-

                                                                                                                                                           §

                                                                                                                                                           0\
'Not included became of uncertainly
Source  Rebm el al. 1982

-------
                                                 Environmental Face   75

     Reaction of vapor-phase chloroform with photochemically generated
hydroxyl radicals in the -atmosphere is probably the primary degradation
mechanism for this compound in air.  The half-life for this reaction in a
typical atmosphere has been estimated to be 70 to 79 days (Atkinson
1985). Chloroform is less reactive in photochemical smog situations (in
the presence of NOX),  with a degradation half-life of 260 days
(Diraitriades and Joshi 1977).  The relatively slow rate of degradation of
chloroform in air suggests that chloroform vapor has the potential to be
transported over long distances.  Assuming a tropospheric-to-
stratospheric turnover time of 30 years, <1% of the tropospheric
chloroform is predicted to diffuse into the stratosphere (Callahan et
al. 1979). Thus, diffusion into the stratosphere is not expected to be
an important fate process.

6.3.2  Water
     Chloroform evaporates rapidly from water, with the rate of
evaporation depending on such conditions as rate of reaction,
temperature, and water depth (NLM 1987). Two laboratory studies on the
evaporation of chloroform from stirred (200-2040 rpm) beakers of water
gave volatilization half-lives ranging from 27 min up to 9 h (Rathbun
and Tai 1981; Dilling 1977).
     A modeling study of the fate of chloroform in a pond, river,
oligotrophic lake, and eutrophic lake revealed that the dominant removal
mechanism in each case was volatilization. Volatilization half-lives
were predicted to be 36 h, 40 h,  10 days, and 9 days, respectively (EPA
1985a). Based on field monitoring data, the overall half-life of
chloroform has been estimated to be 1.2 days in the Rhine River and 31
days in a lake in the Rhine basin (Zoeteman et al. 1980).
     Measured KOc values for chloroform in soil range from 0 to 40,
suggesting that physical adsorption of chloroform to suspended solids
and sediments in water would not be significant (Hutzler et al. 1983)  A
modeling study of chloroform in water estimated that the percentage of
total chloroform found in sediments of a typical river, pond,
oligotrophic lake, and eutrophic lake would be 3.07, 8.1, 0.05, and
0.06, respectively (EPA 1985a). This prediction is supported by sediment
monitoring data that indicate that this compound has not been detected
or was detected at low concentrations in sediment (Ferrario et al. 1985,
Helz and Hsu 1978). Field experiments in which chloroform was injected
into an aquifer showed that chloroform was retained poorly by aquifer
material  (Roberts et al. 1982).
     The hydrolysis half-life of chloroform is >3000 years  in water at
pH 7 and 298 K  (Mabey and Mill 1978). Since chloroform  does not absorb
UV light wavelengths >175 run, this compound is not expected  to photolyze
under environmental conditions (A > 290 nm) (Callahan et al.  1979).
     Conflicting data are available regarding the biodegradation of
chloroform. Although slow but substantial biodegradation can  occur when
the proper microbial populations exist  and are acclimated  to  the
chemical, under aerobic conditions, some studies have shown  that  little
or no degradation occurs  in up to 25 weeks  (Bouwer et al.  1981a,
Kawasaki  1980, Heukelekian and Rand 1955). In contrast, other
investigators have reported substantial degradation  in  much  shorter

-------
 76   Section 6

 periods of time: <49% in 7 days,  100%  in 28  days  (a large  fraction of
 this loss was attributed to volatilization),  25%  in 14  days,  and 67%  in
 24 days (Tabak et al. 1981,  Bouwer et  al.  1981b,  Flathman  and Dahlgran
 1982).  Under anaerobic conditions,  slow  degradation has been  reported
 after acclimation (Bouwer and McCarty  1983).  Wilson et  al.  (1983)
 observed no degradation when chloroform  was  incubated in aquifer
 material for 27 weeks.

      The bioconcentration factor  of chloroform  in four  different fish
 species was found to be <10  times the  concentration in  ambient water
 (Barrows et al.  1980, Anderson and Lusty 1980). This suggests  that
 chloroform has little or no  tendency to  bioconcentrate  in  aquatic
 organisms.

 6.3.3   Soil

      The relatively  high vapor pressure  of chloroform (159 mm  Hg at
 20°C),  suggests  that this compound  will  volatilize  rapidly from  dry soil
 surfaces (Boublik et al.  1984). Evaporation from  moist  soil surfaces is
 also  expected to be  significant since  this compound does not adsorb to
 soil  and appears to  volatilize fairly  rapidly from  water.

     Chloroform  has  been found to adsorb strongly to peat moss,  less
 strongly to clay,  very slightly to  dolomite limestone,  and not at all to
 sand  (Dilling et al.  1975). The KOc  for  chloroform  in two soils  was
 measured to be 40, and three other  soils with lower organic carbon
 content  showed no adsorption (Hutzler  et al. 1983). The retardation
 factor of chloroform applied to a soil column was found to be  <1.5
 (Wilson  et  al. 1981).  These data suggest that chloroform would be highly
 mobile in soil.

     Based  on the  data in aquatic media,  the chemical reaction of
 chloroform  in soil does  not appear  to be a significant fate process.

     No  data  on  the  biodegradation of chloroform  in soil were  found in
 the available literature.  Based on data  in aquatic media, it appears
 that chloroform  may  biodegrade  to some extent under both aerobic and
anaerobic conditions,  provided  that suitable microbial po-ilations are
present  and that  acclimitization to the chemical has occurred.

-------
                    7.  POTENTIAL FOR HUMAN EXPOSURE

7.1  OVERVIEW

     Chloroform is both a man-made and naturally occurring compound,
although anthropogenic sources are responsible for most of the
chloroform found in the environment.  Most of the chloroform released co
the environment will eventually end up in the atmosphere, whereas much
smaller amounts will eventually end up in groundwater. In the
atmosphere, chloroform may be transported long distances before
ultimately being degraded by photochemical reaction. This has been
substantiated by the detection of chloroform in ambient air in remote
locations far removed from anthropogenic sources. Chloroform leaches
into groundwater primarily from spills, landfills, and industrial
sources. Upon contamination of groundwater, chloroform is expected to
persist for relatively long periods of time.

     The general population is exposed to chloroform by ingestion of
drinking water, inhalation, and consumption of many foods. The average
daily intake of chloroform from both ingestion of finished drinking
water and inhalation has been estimated to range from 64 to 396 /ig/day
(see Sect. 7.2.1 and 7.2.2 on levels monitored or estimated in the
environment in air and in water). Diet may also contribute signif icar>cl
to the daily intake of chloroform.

     A 1981-83 NIOSH survey estimated that 87,600 workers are
potentially exposed to chloroform in the United States; however, this
figure does not include exposure to trade-name products that contain
this compound. Occupational exposure is expected to occur primarily by
the inhalation and dermal routes.

7.2  LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT

7.2.1  Air

     Typical U.S.  environmental background levels of chloroform in
outdoor air in rural/remote, urban/suburban, and source-dominated areas
are 0.02 to 0.2, 0.2 to 3.4 and 0.2 to 13 Mg/m3, respectively
(Brodzinsky and Singh 1982, Class and Ballschmidter 1986, Bozzelli and
Kebbekus 1979, Singh et al. 1982, Harkov et al. 1984, Wallace 1986)
Typical concentrations in indoor air were found to range between 0.07 co
3.6 Mg/n3 (Wallace et al. 1986a, Andelman 198Sa,b). A few investigators
reported the levels of chloroform in personal inhaled air (both indoor
and outdoor air) and exhaled air (Wallace et al. 1986a,b).
Concentrations well above typical background levels have been found. For
example, 110 Mg/n>3 was detected in air samples collected outside of
homes in "Old Love Canal" in Niagara Falls, New York (Barkley et al.

-------
  78    Section  7

  1980). Chloroform has  also been detected in rainwater at concentrations
  as high  as  0.25 pg/L  (Kawamura and Kaplan 1983).

       Assuming that  the average daily intake of air is 20 m3/day  typica'
  values for  the average daily intake of chloroform by inhalation'in
  urban, rural, and source-dominated areas have been estimated to be 0 4
  to 4.0,  4.0 to 68.  and 4.0 to 260 pg, respectively.

  7.2.2  Water

      Chloroform has been monitored at widely varying concentrations in
  surface water, groundwater,  and drinking water throughout the United
  States. Concentrations as high as 0.37 Mg/L in surface water. 490 ug/L
  in groundwater.  and 21,800 Mg/L in landfill leachate have been measured
  (Strachan and Edwards 1984,  Rao et al.  1985,  DeWalle and Chian 1981)
 Chloroform has also been found in a limited number of sediment samples
 with a maximum concentration of 18 MgAg (w/w) detected in sediments
 from Lake Pontchartrain in New Orleans,  Louisiana (Ferrario et al.
 1985) .

      The  level of chloroform in drinking water in the United States was
 determined during the 1975 EPA National  Organics  Reconnaissance Survey
 (NORS) and the 1976-77 EPA National Organic Monitoring Study (NOUS)
 Drinking  water samples from  a total of 137  cities geographically
 distributed across  the United States  were studied.  Combined results of
 the  NORS  and NOMS  reveal  that chloroform was detected in 99.5%  of the
 finished  drinking water samples.  Concentrations  ranged from below
 detection limits  to  311 pg/L. with concentrations in  most of the samples
 ranging between  32 and 68  Mg/L  (Brass  et al. 1977,  Symons et al.  1975)
 Assuming  that  the average  person  consumes 2 L  of  water  per  day,  the
 average daily  intake of chloroform by  ingestion of water has been
 estimated to be  64 to  136  /ig.

      The  main  source of chloroform found in municipal drinking  water is
 the chlorination of  naturally occurring  humic  materials  found in raw
 water supplies (Cech et al. 1982.  Bellar et al. 1974).  The  concentration
 of chloroform  in drinking  water has been found to increase  with time
 (Kasso  and Wells 1981). Thus, the  concentration of  chloroform increases
 as water  moves through  distribution systems (Varma  et al.  1984).

 7.2.3   Soil

      Monitoring data for chloroform in soil were  not  located in the
 available  literature.

 7.2.4  Other

      Chloroform has  been detected  in various foods  at the following
 levels: seafood, 3 to 180 MgAg; dairy products,  1.4  to  56  ^gAg: meat
 1 to 4 MgAg;  oil/fats, 2  to 24 pgAg; beverages, 0.4 to  178  pgAg;
 fruits/vegetable, 2  to  18 ,ig/kg; bread. 2 jigAg;  and mother's milk,  not
quantified (EPA 1980, McConnell et al. 1975, Entz et al.  1982,  Lovegren
et al. 1979, Coleman et al. 1981, Pellizzarl et al. 1982).  Although it
appears that the dietary intake of chloroform may be  substantial, data
are insufficient to predict the daily average.

-------
                                       Potential for Human Exposure   79

     In April 1976,  the U.S.  Food and Drug Administration (FDA)
identified approximately 1900 drug products for humans that contained
chloroform.  Such products included toothpastes, cough syrups,
expectorants, antihistamines,  liniments,  and decongestants.  In July
1976,  the FDA banned the use  of chloroform as an ingredient (active or
inactive) in drug and cosmetic products.  However,  chloroform is  not
considered to be an ingredient if drug products contain residual amouncs
of the compound as a result of its use as a processing solvent in
manufacture  or its formation  as a by-product from the synthesis  of
another ingredient (IARC 1979).  This  suggests that many commodities,
which the general population  may come in  frequent contact with,  may
contain residual amounts of chloroform.

     Chloroform is typically  found in automobile exhaust at a
concentration of 0.027 mg/m3  (EPA 1980).  Chloroform has been detected in
the air above outdoor and indoor pools and in spas, with average
concentrations ranging between <0.1 to 68, 0.5 to 274, and <0.1  to
130 /ig/m3, respectively.  Average chloroform levels in water samples
taken from outdoor pools, indoor pools, and spas were 103 to 158, 8 to
350,  and 2 to 292 /*g/L, respectively  (Armstrong and Golden 1986). The
use of chlorine-containing bleaches and/or scouring powders for  washing
clothes and dishes or during  other household activities may produce
elevated levels of chloroform. Similarly, the indoor use of certain
rodenticides may produce higher levels of chloroform in indoor air
(Wallace et al.  1987). Volatilization of  chloroform from water during
showering may be a substantial source of  inhalation exposure (Andelman
1985a,b; Wallace, 1986).

7.3  OCCUPATIONAL EXPOSURES
     A National Occupational  Hazard Survey (NOHS) conducted between 19"2
and 1974 estimated that 215,000 workers in the United States are
potentially exposed to chloroform (NIOSH  1984). This figure includes 46-
of observations termed as "generic" by NIOSH, that is, the surveyor
observed a product in some type of general use that led NIOSH to suspecc
that the specific agent (in this case chloroform) was contained in thac
product. A survey conducted between 1981  and 1983 estimated that 86,700
workers in the United States  are potentially exposed to chloroform
(NIOSH 1987b). This figure is based on actual observations only and does
not include exposure to trade-name products that contain Chloroform.
Results of a study of 350 subjects living in Bayonne, New Jersey,
indicate that the breath levels and personal air exposures of people who
currently work in a paint store, had recently been in a paint store, or
had recently used pesticides were significantly elevated  in comparison
to people not involved  in these activities (Wallace 1986). Based on the
physical properties and uses of chloroform, it has been concluded  thac
occupational exposure would occur primarily by inhalation and dermal
contact.

7.4  POPULATIONS AT HIGH RISK
     Since chloroform  is a component of  chlorinated drinking water,
people whose water supplies are chlorinated have the potential  for
exposure. Raw surface water supplies are  usually disinfected by
chlorination, although  raw groundwater supplies  (from deep wells)  are

-------
80   Section 7

commonly distributed with no disinfection (Singley 1984). Approximately
12,000 of 60,000 public water supplies in the United States use surface
water as a source for raw water. These systems supply 66% of the
population using public water supplies (EPA 1985d).
     As reviewed by EPA (1985a), several factors,  including ethanol
ingestion and starvation, can potentiate the toxicity of chloroform to
the liver. Therefore, people who drink alcohol or who diet may be at
higher risk.

-------
                         8.  ANALYTICAL METHODS

     Several methods are available for the analysis of chloroform in
different environmental and biological matrices  The choice of a
particular method will depend on the nature of the sample matrix, the
required precision, accuracy, and detection limit, and the cost and
turnaround time of the analysis. Biological samples for a wide spectrum
of halogenated volatile substances, including chloroform, can be
screened by injecting static head-space gas or solvent-extracted liquid
into a gas chromatograph equipped with an electron capture detector
(Foerster and Garriott 1981, NYDEC 1985). Preconcentrations of samples
prior to quantification increase the detection limits of the method
used. In air samples, the preconcentration usually is done by passing
the air through a suitable adsorbent during sample collection. The
dynamic headspace technique commonly known as purge-and-trap provides an
excellent method for the preconcentration of chloroform from water,
food, soil, sediment, and biological matrices. The purge-and-trap method
also provides a preliminary separation of chloroform from other less
volatile and nonvolatile components in the samples, thereby eliminating
the need for extensive separation of the components by a gas
chromatographic column prior to quantification. The best specificity a-^c
sensitivity for chloroform quantification is obtained by an electrolyc :..-
conductivity detector in the halide detection mode, since this deteccor
is relatively insensitive to nonhalogenated species and very sensitive
to halogenated species. Although mass spectrometry is less sensitive
than an electrolytic conductivity detector, it is often used as a
confirmation method, since the ion-chromatograms of the fragment and
parent ions provide an alternative confirmation in addition to the gas
chromatographic retention time. For details of the analytical methods,
including the advantages and disadvantages, specificity,
reproducibility, and sensitivity, refer to the references cited in
Table 8.1.

8.L  ENVIRONMENTAL MEDIA

     Analytical methods and detection limits for chloroform in various
environmental matrices are identified in Table 8.1. These methods are
based primarily on gas chromatographic separation, with subsequent
quantification by various methods. Table 8.1 includes the EPA (1987a)
methods required by the EPA Contract Laboratory Program (CLP) for
analysis of chloroform in water, soil, and sediment.

8.2  BIOMEDICAL SAMPLES

     Analytical methods and detection limits for chloroform in various
biomedical samples are identified in Table 8.1. Biological samples are
commonly pretreated for analysis by a purge-and-trap method or a

-------
Table 8.1.  Analytical methods for cbloroTona
Sample matrix
Air

Ambicni air and slacks

Air


Ekhaled air (breath)

Groundwater, liquid and
solid matrices



Wasicwiter



Blood, urine, and tissue

Volatile food components







Drinking water








Sample preparation"
Adsorption on charcoal, desorp-
two with carbon disulfide
Tcoai OC adsorption and thermal
doorption
None


Sample collected in Tedlar bag
preconcentrated by Tenax-GC.
thermal doorptioo
Direct injection of headspace
gas (EPA method 5020) or
preconceniraiion by purge-and-
trap and thermal desorption
(EPA method 5030)
Preconceniraiion by purge-and-
trap method and thermal desorp-
non

Purgc-and-irap, thermal dcsorp-
tion
Direct injection of headspace
gas






Direct injection or purge-and-
trap on GC column (automated)



Solvent extraction

Purge-and trap and thermal
dcsurplion
Quantification method"
GC/FID
(NIOSH method 1003)
GC/FID or ECD

GC/ECD


HRGC/FID and HRGC/MS

GC/HSD or FID
(EPA method 8010)



GC/HSD or MS
(EPA methods 601
and 624)

GC/HSD or GC/MS

GC/ECD or MS







GC/ECD.
GC/Hall



GC/HD.
GC/MS
dC/MS

Detection limit
0 7 mg/m1
for 15-L sample
NR*

1 5 Mg/m'


NR

OOSjig/L




005Mg/L(forHSD)
1 6 Mg/L (for MS)


010 Mg/L
(blood and urine)
4 2 Mg/kg
(beverages)
12 5 Mg/kg
(dairy products)
18 «.g/kg
(meals)
28 jig/kg
(fats/oils)
1 «ig/L (direct)
0 1 Mg/L (purge-
and-trap)


004/ig/L
NR
0 1 ^g/L

Accuracy/Recovery
97% ai
100-500 mg/m1
NR

NR


NR

102% al 044-50 ^g/L




102% alO 44-50 ^g/L
(for HSD)
101% at 10-100 pg/L
(for MS)
NR

NR

NR

NR

NR

103- 126% at 3S-70
Mg/L (direct)
91-106% at 35-70

-------
                                                                       Tible8.l  (continued)
Sample maim
Drinking water

Scawaicr and freshwater


Water

Water
Blood

Whole blood

Adipose tissue and serum

Tap water and whole blood

Serum and adipose tissue

Water, serum, and urine




Water, soil, and sediment



Water, soil, and sediment


fl
Sample preparation0
None (direct injection)
None (direct injection)
Solvent extraction with
pcntane

Permeation through a silicon
polycarbonate membrane
Solvent extraction
headspace analysis

Purge-and-lrap and thermal
desorplion
Purge-and-lrap and thermal
dcsorption
Solvent extraction

Purge-and-trap and thermal
desorplion
Solvent extraction




Solvent extraction

r

Purge-and-lrap and thermal
desorplion


Quantification method"
GC/ECD
GC/MS
GC/ECD


GC/FID

GC/ECD
GC/FID

GC/MS

GC/Hall with GC/MS
confirmation
HRGC/ECD with HRGC/MS
confirmation
GC/Hall with GC/MS
confirmation
HRGC/ECD




GC/hID (screening lest)
(EPA-CLP)


GC/MS
(EPA-CLP)


Detection limit

5
to
i— .
n
o
to
K.
a
n
n
O
Q
in
   "GC. gas chromatography. HRGC, high-resolution gas chromaiography, FID. flame lomzaiion detector. I ISP, electrolytic conductivity detector, ECD. electron capture dctec-
lor. Hall. Hall conductivity deteclor. MS, mass spectrometry
   6 Not reported

-------
84   Section 8

variation of that method (EPA 1985a).  Details of the pretreatment and
quantification methods are provided in the cited references.

     Caution should be exercised in interpreting the results from the
analysis of chloroform levels in body tissues.  Tetrachloroethylene,
trichloroethylene, trichloroacetaldehyde,  and trichloroacetic acid can
all be metabolic precursors of chloroform  (Peoples et al.  1979).  The
presence of any of these compounds in body tissues may cause
artifactually higher values for chloroform.  Heating of tissues during
treatment of samples as a part of the  analytical procedure may produce
artifactually higher values of serum chloroform in the presence of
serum-bound trichloroacetic acid because of  thermal degradation of the
latter compound to chloroform. It is probably for these reasons that a
poor correlation between chloroform exposure and tissue levels has been
found.

-------
                                                                      85
                   9.  REGULATORY AND ADVISORY STATUS

 9 . 1   INTERNATIONAL

      IRPTC  (1987) reported a World Health Organization  (WHO) drinking
 water guideline of 30 pg/L for chloroform.

 9 . 2   NATIONAL

 9.2.1 Regulations

      The current OSHA PEL for chloroform is 50 ppm in the workroom
 atmosphere  (OSHA 1985) . The EPA amended the National Interim Primary
 Drinking Water Regulations, adding a section on the control of organic
 halogenated contaminants. The limit for total trihalomethanes , including
 chloroform, was 0.1 mg/L. This limit was based partly on estimates of
 cancer risk and partly on technical and economic feasibility. It applies
 only  to water supplies serving more than 10,000 consumers (EPA 1980
 1985a).

      The EPA (1980) derived cancer-based ambient water quality criteria
 for chloroform. A potency estimate from the NCI (1976) bioassay with
 female mice was used to derive these criteria. Chloroform levels
 associated with incremental increases of cancer risk of 10*5, 10'6, and
 10'7  were 1.9, 0.19,  and 0.019 /ig/L, respectively, if exposure is
 assumed to be from drinking water and from consuming fish and shellfish
 from  contaminated ambient water.  If exposure is assumed to be from
 consumption of contaminated fish and shellfish only, the corresponding
 criteria are 157,  15.7,  and 1.57 Mg/L in ambient water.
     Chloroform levels in drinking water associated with incremental
increases of cancer risk of 10"4, 10'5, 10'6, and 10'7 are 600, 60, 6,
and 0.6 ^g/L, respectively (EPA 1987b) .
     Chloroform is regulated by the Clean Water Act Effluent Guidelines
for the following industrial point sources: electroplating, organic
chemicals, steam electric, asbestos, timber products processing, metal
finishing, paving and roofing, paint formulating, ink formulating, gum
and wood, carbon black, metal molding and casting, coil coating, copper
forming, and electrical and electronic components (EPA 1988).

     Federal law (CERCLA 103a and 103b) requires that the National
Response Center be notified when there is a release of a hazardous
substance in excess of the reportable quantity (RQ) . The RQ for
chloroform is 5000 Ib (EPA 1985e) ;  however, this RQ is subject to change
when the carcinogenicity and/or toxicity assessment is completed (EPA
1987c).

-------
 86    Section 9

      Federal law (Section 302  of  SARA) requires any facility where an
 extremely hazardous substance  is  present  in excess of the  threshold
 planning quantity (TPQ)  to notify the state emergency planning
 commission.  The TPQ for  chloroform is 10.000 Ib (EPA 1987c). Federal la-
 Section 304 of SARA)  also requires  immediate reporting of  releases of
 hazardous substances to  local  emergency planning committees and the
 state emergency planning commission.

      Federal law (Section 313  of  SARA) requires owners and  operators of
 certain  facilities  that  manufacture, process, or otherwise  use
 chloroform to report annually  to  both EPA and the state in which the
 facility is  located their releases of chloroform to the environment (EPA
 1987d).

      The EPA intends to  list chloroform as a hazardous air pollutant
 under Section 112 of the Clean Air Act (EPA 1985f).

      The FDA approved  chloroform  for use as an indirect food additive
 (i.e., a component  of  articles that may come in contact with food.) It
 has been exempted from tolerance  when used as a solvent in pesticide
 formulations applied to  crops. The FDA has restricted its use in drugs
 and cosmetic products  as a result of the positive NCI (1976) bioassay
 (EPA  1985a).

 9.2.2  Advisory Guidance

 9.2.2.1  Air

      NIOSH  (1974) recommended  that atmospheric chloroform concentrations
 not exceed 10 ppm as a TWA for up to a 10-h workday, 40-h workweek.
 NIOSH  (1974)  also proposed a 10-min ceiling level of 50 ppm. These
 criteria were designed to protect against mild CNS depression,
 irritation,  and fetal  abnormalities (which were considered  to occur at
 concentrations  lower than those causing liver damage).  The NIOSH
 criterion was lowered  to 2  ppm in 1976 in response to the positive
 results  of the  NCI  (1976) bioassay (NIOSH 1977).  This level applied to
halogenated  anesthetics,  including chloroform,  and was selected because
 it was the lowest level  detectable with sampling and analysis
 techniques,  and not because any safe level of chloroform exposure had
been defined (EPA 198Sa).

     ACGIH (1986) recommended a TLV-TWA of 10 ppm to protect against
carcinogenicity and embryotoxicity as a result of occupational exposure
 to chloroform in the atmosphere.  ACGIH (1986) gave chloroform an A2
classification--substances  suspect of carcinogenic potential for man.

     Chloroform levels in air associated with incremental increases of
cancer risk  of  10'4, 10'5   10'6  and 10'7 are 4.3 x 10'3, 4.3 x 10'4.
4.3 x 10'5,  and 4.3 x  10'6 mg/m3  (8.8 x 10'4. 8.8 x 10'5, 8.8 x 10'6.
and 8.8 x 10'7  ppm), respectively (EPA 1985a).

-------
                                     Regulacory and Advisory Status   37

9.2.3  Data Analysis

9.2.3.1  Reference dose

     The EPA (1987d) has calculated a reference dose (RfD)  of 0 01
mg/kg/day for chloroform.  This value is based on the LOAEL of 12.9
mg/kg/day for increased fatty cyst formation in livers of dogs exposed
to 15 mg/kg/day, 6 days/week,  for 7.5 years (Heywood et al. 1979). The
RfD is calculated according to the methods of Barnes et al. (1987) as
follows:

     RfD - 15 mg/kg/day x 6 days/7 days/(100) (10)  - 0.01 mg/kg/day

     where:    15 mg/kg/day - LOAEL
              6 days/7 days - factor to expand over a 7-day week
                        100 - uncertainty factor for inter- and
                              intraspecies extrapolation
                         10 - uncertainty factor appropriate for using
                              a LOAEL in the absence of a NOAEL

9.2.3.2  Carcinogenic potency

     The EPA (1985a) performed a quantitative carcinogenicity risk
assessment for chloroform.  Five data sets were analyzed: incidences of
liver tumors in female mice (NCI 1976), liver tumors in male mice (NCI
1976), kidney tumors in male rats (NCI 1976), kidney tumors in male mice
(Roe et al. 1979), and kidney tumors in rats (Jorgenson et al. 1985).
For inhalation exposure. EPA (1985a) chose to combine the potency
estimates from NCI (1976)  liver tumor data for male and female mice  The
geometric mean of these two estimates resulted in the q * of 8.1 x 10"2
(mg/kg/day)'1. Using this q *  EPA (1985a) calculated upper-bound
estimates of cancer risk for exposure to 1 Mg/m^ in air to be 2.3 x
10'5. This q.* for inhalation exposure to chloroform was validated by
the CRAVE (Carcinogen Risk Assessment Verification Endeavor) work group
on August 26, 1987 (EPA 1987b). The CRAVE work group (EPA 1987b) also
validated a q * for oral exposure via drinking water of 6.1 x 10*3
(mg/kg/day)"^ based on the incidence of kidney tumors in male rats in
the study by Jorgenson et al.  (1985). The upper-bound estimate of cancer
risk for exposure to 1 pg/L in water is 1.7 x 10~7.

     Chloroform has been classified as a Group B2 carcinogen, that is, a
probable human carcinogen,  based on sufficient evidence from animal
studies and inadequate evidence from human studies  (EPA 1986a, 1987b).
IARC (1979, 1982) classified chloroform in Group 2B.

9.3  STATE

     Regulations and advisory guidance from the states were not
available.

-------
                                                                      89
                            10.   REFERENCES
ACGIH (American Conference of Governmental Industrial Hygienists).  1986.
Documentation of the Threshold Limit Values and Biological Exposure
Indices. 5th ed.  Cincinnati, OH,  p. 130.

Adriani J.  1970. The pharmacology of anesthetic drugs. Thomas CC, ed.
Springfield, IL: pp. 57-60 (cited in EPA 1985a).

Agustin JS, Lim-Sylianco CY.  1978. Mutagenic and clastogenic effects of
chloroform. Bull Phil Biochem Soc 1:17-23 (cited in EPA 1985a).

Ahlstrom RC, Steele JM.  1979. Chlorocarbons, hydrocarbons (CH3C1).  In:
Grayson M,  Eckroth D, eds. Kirk-Othmer Encyclopedia of Chemical
Technology, 3rd ed. Vol  5. New York: John Wiley and Sons, pp. 677-685.

Ahmed AE, Kubic VL, Anders MU. 1977.. Metabolism of haloforms to carbon
monoxide. I. In vitro studies. Drug Metab Dispos 5:198-204.

Amoore JE,  Hautala E. 1983. Odor as an aid to chemical safety: Odor
thresholds compared with threshold limit values and volatilities for 214
industrial chemicals in air and water dilution. J Appl Toxicol
3:272-290.

Andelman J. 1985a. Human exposures to volatile halogenated organic
chemicals in indoor and outdoor air. Environ Health Perspect 62:313-318

Andelman J. 1985b. Inhalation exposure in the home to volatile organic
contaminants of drinking water. Sci Total Environ 47:443-460.

Anders MW,  Stevens JL, Sprague RV, Shaath Z. 1978. Metabolism of
haloforms to carbon monoxide. II. In vivo studies. Drug Metab Dispos
6:556-560.

Anderson DR, Lusty EB. 1980.  Acute Toxicity and Bioaccumulation of
Chloroform to Four Species of Freshwater Fish: Sal/no gairdneri, Rainbow
Trout, Lepoals macrochirus, Bluegill....Report CR-0893. Nuclear
Regulatory Commission, NTIS PNL-3046  (cited in NLM 1987).
*Key studies.

-------
  90    Section 10

  Antoine  SR,  DeLeon IR,  O'Dell-Smith RM. 1986. Environmentally
  significant  volatile  organic pollutants in human blood. Bull Environ
  Contain Toxlcol  36:364-371.

  Armstrong  DW, Golden  T.  1986. Determination of distribution and
  concentration of  trihalomethanes in aquatic recreational and therapeutic
  facilities by electron  capture GC. LC-GC 4(7):652-655.

  Atkinson R.  1985.  Kinetics and mechanisms of the gas-phase reactions of
  nydroxyl radical with organic compounds under atmospheric conditions
  Chem Rev 85:69-201.

  Bailie MB, Smith JF, Newton JH,  Hook JB.  1984.  Mechanism of chloroform
  nephrotoxicity.  IV. Phenobarbital potentiation of in vivo chloroform
 metabolism and toxiclty in rabbit kidneys.  Toxicol Appl Pharmacol
  74:285-292 (cited  in EPA 1985a).

 Balster RL, Borzelleca JF.  1982.  Behavioral toxicity of trihalomethane
 contaminants of drinking water in mice.  Environ Health Perspect
 ^€> 112 7 * 13o.

 Barkley J et al. 1980. Gas  chromatography mass  spectrometry computer
 analysis  of volatile halogenated  hydrocarbons  in man and his
 environment.  A multimedia environmental  study.  Biomed Mass  Spectrom
 / • Ai J * m il / •

 Barnes  D  et al.  1987.  Reference dose  (RfD):  Description and use in
 health risk assessments. Appendix A of  the  Integrated Risk  Information
 System (IRIS). Washington,  DC: Office of Health  and Environmental
 Assessment,  Office of Research and  Development,  EPA 600/8-86-0321.

 Barrows ME,  Petrocelli SR, Macek  KJ, Carroll JJ.  1980.  Bioconcentration
 and  elimination  of selected water pollutants by bluegill  sunfish
 (Lepomis macrochirus).  In Dyn, Exposure Hazard Assess  Toxic  Chem.  Ann
 Arbor,  MI:  Ann Arbor Science, pp. 379-392.

 Bellar  TA,  Llchtenberg JJ, Kroner RC. 1974. The occurrence of
 organohalides In chlorinated drinking water. J Am Water Works Assoc
 66:703-706  (cited  In EPA 1985a).

 Bennet  RA, Whlgham  A.  1964. Chloroform sensitivity  of  mice.  Nature
 204:1328.

Blanchard RD. Hardy JK.  1986. Continuous monitoring device for  the
58(7V1529 15 " V°latlle or«anlc Priority pollutants. Anal  Chem


* Bomskl H, Sobolweska A, Strakowskl A.  1967. Toxic damage of the  liver
J? ?5;0f°form ln chemlcal Industry workers.  Arch Gewerbepathol Gewerbehy
24:127-134 (FRG) (translated from German).

-------
                                                         References   9 "..

Boublik T, Fried V, Hala E.  1984.  The vapor pressures of pure
substances: Selected values  of the temperature dependence of the vapor
pressures of some pure substances  in the normal and low-pressure region
Vol. 17. Amsterdam, Netherlands:  Elsevier Sci Publ.

Bouwer EJ, McCarty !*L. 1983.  Transformations of 1- and 2-carbon
halogenated aliphatic organic compounds under methanogenic conditions
Appl Environ Microbiol 45(4):1286-1294.

Bouwer EJ, McCarty PL, Lance  JC.  1981a. Trace organic behavior in soil
columns during rapid infiltration  of secondary wastewater. Water Res
15:151-159.

Bouwer EJ, Rittman B, McCarty PL.  1981b. Anaerobic degradation of
halogenated 1- and 2-carbon  organic compounds. Environ Sci Technol
15:596-599.

Bowman FJ, Borzelleca J, Munson AE. 1978. The toxicity of some
halomethanes in mice. Toxicol Appl Pharmacol 44:213-215.

Bozzelli JW, Kebbekus BB. 1979. Analysis of selected volatile organic
substances in ambient air,  final report Apr-Nov. 1978. Newark, NJ: New
Jersey Institute of Technology.

Branchflower RV, Pohl LR. 1981. Investigation of the mechanism of the
potentiation of chloroform-induced hepatotoxicity and nephrotoxicity by
methyl n-butyl ketone. Toxicol Appl Pharmacol 61:407-413  (cited in EPA
1985a).

Branchflower RV, Nunn DS, Highet RJ,  Smith JH, Hook JB, Pohl LR. 1984
Nephrotoxicity of chloroform:  Metabolism to phosgene by the mouse
kidney.  Toxicol Appl Pharmacol 72:159-168.

Brass HJ, Feige MA, Halloran T, Mello JW, Munch D, Thomas RF. 1977. The
National Organic Monitoring  Survey: Sampling and analyses for purgeable
organic compounds. In: Drinking Water Quality Enhancement Source
Protection, pp. 393-416.

Brodzinsky R, Singh HB. 1982.  Volatile organic chemicals  in the
atmosphere: An assessment of available data. Menlo Park,  CA: Atmospheric
Science Center, SRI International. Contract 68-02-3452.

Brown DM, Langley PF, Smith  D, Taylor DC. 1974a. Metabolism of
chloroform. I. The metabolism of l^C-chloroform by different species
XenobioCica 4:151-163.

Brown BR Jr, Sipes IG, Sagalyn AM. 1974b. Mechanisms of acute hepatic
toxicity. Chloroform, halothane, and glutathione. Anesthesiology
41:554-561.

Bull RJ et al. 1986. Enhancement of the hepatotoxicity of chloroform  in
B6C3F1 mice by corn oil. Implications  for chloroform carcinogenesis.
Environ Health Perspect 69:49-58.

-------
  92   Section  10

  Bureau  International Technique des Solvents Chlores. 1976.
  Standardization of methods for the determination of traces of some
  volatile chlorinated aliphatic hydrocarbons in air and water by gas
  chromatography. Anal Chim Acta 82:1-17 (cited in IARC 1979).

  Burkhalter J, Balster RL. 1979. Behavioral teratology evaluation of
  chloroform in mice. Neurobehav Toxicol 1:199-205 (cited in EPA 1985a)

  Caldwell KK, Harris RA. 1985. Effects of anesthetic and anticonvulsant
  drugs on calcium-dependent efflux of potassium from human erythrocytes
  Eur J Pharmacol 107(2) : 119-125.

 Callen DF,  Wolf CR, Philpot RM. 1980. Cytochrome P-450  mediated genetic
 activity and cytotoxicity of seven halogenated aliphatic hydrocarbons in
 Saccharomyces cerevLsiae.  Mutat Res 77:55-63.

 Callahan MA,  Slimak MW,  Gabel NW,  et al.  1979.  Water-related
 environmental fate of 129 priority pollutants.  Vol.  II.  Washington  DC-
 EPA.  EPA-440/4-79-029B.

 Capel ID,  Dorrell  HM,  Jenner M.  Pinnock MH, Williams DC.  1979.  The
 effect  of  chloroform ingestion on  the growth of some murine  tumors  Eur
 J Cancer 15:1485-1490.

 Cech  I,  Smith V, Henry J.  1982.  Spatial and seasonal variations  in
 concentration of trihalooethanes in drinking water.  In:  Albaiges J,  ed.
 Analytical  Techniques  in Environmental Chemistry.  II. New York-  Pereamon
 Press,  pp.  19-38.

 * Challen PJR, Hickish  DE, Bedford J.  1958. Chronic  chloroform
 intoxication.  Br J  Ind Med 15:243-249.

 Chemline. 1987. On-line  Computer Data Base. National  Library of
 Medicine. Retrieval Data 6/87.

 Chenoweth MB.,  Robertson  DN, Erly DS,  Goekhe K.  1962.  Blood and  tissue
 levels of ether, chloroform,  halothane, and methoxyfluorane  in dogs
 Anesthesiology 23:101-106.

 Chiou WL. 1975. Quantitation  of hepatic and pulmonary first-pass effects
 and its  implication in pharmacokinetic study. I. Pharmacokinetics  of
 chloroform  in  man. J Pharmacokinet  Biopharm 3:193-201.

 Chu I, Secours V, Marino I, Villeneuve DC. 1980. The acute toxicity of
 four trihalomethanes in male  and female rats. Toxicol Appl Pharmacol
 52:351-353.

 * Chu I, Villeneuve DC, Secours VE, Becking GC. 1982a. Toxicity of
 trihalomethanes.  I. The acute and subacute toxicity of chloroform,
bromodichloromethane, chlorodibromomethane, and bromoform  in rats
J Environ Sci Health B17:205-224.

-------
                                                         References   93

* Chu I, Villeneuve DC,  Secours VE,  Becking GG,  Valli VE. 1982b.
Toxicity of trihalomethanes.  II. Reversibility of toxicological changes
produced by chloroform,  bromodichloromethane,  chlorodibromomethane, and
bromoform in rats.  J Environ Sci Health 817:225-240.

Cianflone DJ,  Hewitt WR.  Villeneuve  DC,  Plaa GL.  1980. Role of
biotransformation in the alterations of chloroform hepatotoxicity
produced by Kepone  and Mirex.  Toxicol Appl Pharmacol 53:140-149 (cited
in EPA 1985a).

Class T, Ballschmidter K. 1986. Chemistry of organic traces in air. VI
Distribution of chlorinated Cl-C4-hydrocarbons in air over the northern
and southern Atlantic Ocean.  Chemosphere 15(4):413-427.

CMR (Chemical Marketing Reporter).  1986a.  Chemical Profile: Chloroform
New York: Schnell Publishing,  February 17.

CMR (Chemical Marketing Reporter).  1986b.  U.S. Imports of Chemicals and
Related Materials.  New York:  Schnell Publishing,  April 7.

Cohen EN, Hood W. 1969.  Application  of low-temperature autoradiography
studies of the uptake and metabolism of volatile anesthetics in the
mouse. Anesthesiology 30:306-314.

Coleman EC, Ho C, Chang SS.'1981. Isolation and identification of
volatile compounds  from baked potatoes.  J Agric Food Chem 29:42-48.

Coleman WE, Lingg RD, Melton RG, Kopfler FC. 1976. The occurrence of
volatile organics in five drinking water supplies using gas
chromatography/mass spectrometry. In: Keith L, ed. Analysis and
Identification of Organic Substances in Water. Ann Arbor MI: Ann Arbor
Science, pp. 305-327.

Condie LW, Smallwood CL,  Laurie RD.  1983.  Comparative renal and
hepatotoxicity of halomethanes: Bromodichloromethane, bromoform,
chloroform, dibromochloromethane, and methylene chloride. Drug Chem
Toxicol 6(6):564-578.

Cornish HH. 1975. Solvents and vapors. In: Cassarett L, Doull J,  eds.
Toxicology, the Basic Science of Poisons.  MacMillan Publishing, p. 503
(cited in EPA 1985a).

Culliford D, Hewitt HB.  1957.  The influence of sex hormone status  on  the
susceptibility of mice to chloroform-induced necrosis of the renal
tubules. J Endocrinol 14:381-393.

Danielsson BR,  Ghantous H, Dencker L. 1986. Distribution of chloroform
and methyl chloroform and their metabolites in pregnant mice. Biol Res
Pregnancy Perinatol 7(2):77-83.

-------
  94   Section  10

  Danni 0, Brossa 0, Burdino E, Mlllillo P, Ugazio G. 1981. Toxicity of
  halogenated hydrocarbons In pretreated rats: An experimental model for
  the study of  integrated permissible limits of environmental poison. Inc
  Arch Occup Environ Health 49:105-112 (cited in EPA 1985a).

  Davidson J. 1988. Written communication to Murphy J, Health Effects ODW
  EPA, from Davidson J, Chairman. Testing Priority Committee  OTS
  March 1. 1988.

  Demi E, Oesterle D. 1985. Dose-dependent promoting activity of
  chloroform in rat liver foci bioassay.  Cancer Lett 29:29-63.

  * Deringer MK, Dunn TB, Heston WE.  1953.  Results of exposure  of strain
  C3H mice to chloroform. Proc Soc Exp Biol Med 83:474-479.

  De Serres FJ,  Ashby J, eds.  1981.  Evaluation of short-term  tests for
 carcinogens.  In:  Progress in Mutation Research.  Vol I.  Elsevier/North
 Holland (cited in EPA 1985a).

 * DeSalva S,  Volpe A,  Leigh G,  Regan T.  1975.  Long-term safety studies
 of a chloroform-containing dentifrice and mouth rinse  in man   Food
 Cosmet Toxicol 13:529-532.

 Deshon HD.  1979.  Carbon tetrachloride.  In:  Grayson M,  Eckroth D, eds
 Kirk-Othmer  Encyclopedia of Chemical Technology,  3rd ed.  Vol  5  New
 York:  John Wiley  and Sons,  pp.  693-703.

 Dewalle  FB,  Chian ESK. 1981.  Detection  of trace  organics  in well water
 near a  solid waste landfill. J  Am Water Works  Assoc 73:206-211.

 Dilley JV, Chemoff N, Kay  D, Winslow N,  Newell  GW.  1977. Inhalation
 teratology studies of  five  chemicals in rats.  Toxicol Appl Pharmacol
 41:196.

 Dilling  WL, Tefertiller NB, Kallos GJ. 1975. Evaporation  rates  of
 methylene chloride,  chloroform,  1,1,1-trichloroethane,
 trichloroethylene,  tetrachloroethylene, and other  chlorinated compounds
 in dilute aqueous  solutions. Environ Sci Technol 9(9):833-838.

 Dilling  W. 1977. Interphase transfer processes.  II.  Evaporation rates  of
 chloromethanes, ethanes, ethylenes,  propanes,  and  propylenes  from dilute
 aqueous  solution.  Comparisons with theoretical predictions. Environ Sci
 Technol  11:405-409.

 Dimitriades B, Joshi SB. 1977. Application of  reactivity criteria in
 oxidant-related emission control in  the USA. In: Dimitriades  B,  ed.
 International Conference on Photochemical Oxidant  Pollution and Its
 Control. Research Triangle Park, NC: EPA. EPA-600/3-77-001B
 pp. 705-711.

 Docks EL, Krishna G. 1976. The role  of glutathione  in chloroform-induced
hepatotoxicity. Exp Mol Pathol 24:13-22.

-------
                                                         References   95

Dow Chemical Company. 1988.  Comments of the Dow Chemical Company on
ATSDR's Toxicological Profile for Chloroform.  Submitted by the Dow
Chemical Company, Midland,  MI,  to Georgi Jones, Director,  Office of
External Affairs, ATSDR,  Atlanta, GA.

Eisenreich SJ,  Looney BB, Thornton JD.  1981.  Airborne organic
contaminants of the Great Lakes ecosystem.  Environ Sci Technol
15(l):30-38.

Ekstrom T, Hoegbers J, Jernstroem B. 1982.  Induction of hepatomas in
mice by repeated oral administration of chloroform with observations or
sex differences. J Natl Cancer  Inst 5:251-255 (cited in EPA 1985a).

Entz RC, Thomas KW, Diachenko GW. 1982. Residues of volatile halocarbons
in foods using headspace  gas chromatography.  J Agric Food Chem
30:846-849.

EPA. 1980. Ambient Water  Quality Criteria for Chloroform.  Office of
Water Regulations and Standards. Washington,  DC: Environmental
Protection Agency. EPA 440/5-80-033. NTIS PB81-117442.

EPA. 1981. Treatment Techniques for Controlling Trihalomethanes in
Drinking Water. Cincinnati,  OH: Municipal Environmental Research Lab.
EPA-600/2-81-156.

EPA. 1982a. Test Methods  for Evaluating Solid Wastes: Physical/Chemical
Methods. 5W-846. 2nd ed.  Office of Solid Wastes.

EPA. 1982b. Methods for Organic Chemical Analysis of Municipal and
Industrial Wastewater. Cincinnati, OH:  Environmental Monitoring and
Support Laboratory. EPA-600/4-82-057.

EPA. 1985a. Health Assessment Document for Chloroform. Final report.
Washington, DC: Office of Health and Environmental Assessment. EPA-
600/8-84-004F.  NTIS PB86-105004/XAB.

EPA. 1985b. Reference Values for Risk Assessment. First draft. ECAO-
CIN-477. Cincinnati, OH:  Environmental Criteria and Assessment Office.

EPA. 1985c. Survey of Chloroform Emission Sources.  Research Triangle
Park, NC: Office of Air Quality. EPA 450/3-85-026.

EPA. 1985d. Criteria Document for Radium in Drinking Water: Draft. April
1985. Washington, DC: Health Effects Branch,  Criteria and Standards
Division (WH-550), Office of Drinking Water.

EPA. 1985e. Notification requirements;  reportable quantities and
adjustments. Final rule and proposed rule. 40 CFR Parts 117 and 302.  Fed
Regist 50(65):13481.

EPA. 1985f. Intent to list chloroform as a hazardous  air pollutant.  Fed
Regist 50(188):39626-39629.

-------
96   Section 10

EPA. L986a. Evaluation of the Potential CarcLnogenicity  of Chloroform
Review draft. Prepared by Carcinogen Assessment Group, Washington,  DC:
Office of Health and Environmental Assessment.   OHEA-C-073-54,  December
1986.

EPA  1986b. Guidelines for the health assessment of suspect
developmental toxicants. Fed Regist 51(185):34028-34040.

EPA. 1987a. EPA Contract Laboratory Program.  Statement of Work for
Organics Analysis, Multi-Media, Multi-Concentration.  Revised 8/87.

EPA. 1987c. Extremely Hazardous Substances List and Threshold Planning
Quantities; Emergency Planning and Release Notification  Requirements.
Fed Regist 52(77):13378-13410.

EPA. 1987d. Toxic Chemical Release Reporting; Community  Right-to-Know.
Fed Regist 52(107):21152-21179.

EPA. 1987e. Integrated Risk Information System (IRIS) reference dose
(RfD) for oral exposure  for chloroform. On Line (Verification date
12/2/85). Cincinnati, OH: Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office

EPA. 1987b. Integrated Risk Information System (IRIS) risk estimate for
carcinogenicity for chloroform. On line. Input pending (Verification
date 8/26/87). Cincinnati, OH: Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office

EPA. 1988. Analysis of Clean  Water Act Effluent Guidelines Pollutants.
Summary  of the Chemicals Regulated by Industrial Point Source Category
40  CFR Parts 400-475. Draft.  Prepared by Industrial Technology Division
(WH 552) Office of Water Regulations and Standards. Office of Water.
Washington, DC: EPA.

EPA-NIH  (National Institute of Health). 1987.  OHM-TADS  (Oil  and
Hazardous  Materials Technical Assistance Data  System). On line.

Eschenbrenner AB, Miller E.  1945a.  Induction of hepatomas in mice  by
repeated oral administration of chloroform with observations on sex
differences. J Natl Cancer  Inst 5:251-255.

Eschenbrenner A3, Miller E.  1945b.  Sex differences in kidney morphology
and chloroform necrosis. Science  102:302-303.

Feingold A,  Holaday  DA.  1977. The pharmacokinetics of metabolism of
inhalation anaesthetics. Br J Anaesth 49:155-162.

Ferrario JB,  Lawler  GC,  DeLeon IR,  Laseter JL. 1985.  Volatile organic
pollutants in biota  and sediments of Lake Pontchartrain. Bull Environ
Contam  Toxicol  34(2):246-255.

-------
                                                         References   97

Flathman PE, Dahlgran JR.  1982.  Correspondence on:  Anaerobic degradation
of halogenated 1- and 2-carbon organic compounds.  Environ Sci Techno1
16:130.

Foerster EH, Garriott JC.  1981.  Analysis for volatile compounds in
biological samples.  J Anal Toxicol 5:241-244.

Fry BJ, Taylor T, Hathway DE.  1972.  Pulmonary elimination of chloroform
and its metabolites  in man.  Arch Int Pharmacodyn 196:98-111.

Fujii T. 1977. Direct aqueous  injection gas chromatography-mass
spectrometry for analysis of organohalides in water at concentrations
below the parts per  billion level. J Chromatogr 139:297-302.

Gettler AO. 1934. Hedicolegal  aspects of deaths associated with
chloroform or ether. Am J Surg 26:168-174.

Gettler AO, Blume H. 1931. Chloroform in the brain, lungs, and liver.
Quantitative recovery and determination. Arch Pathol 11:554-560.

Gocke E, King MT, Eckhardt K,  Wild D. 1981. Mutagenicity of cosmetics
ingredients licensed by the European communities.  Mutat Res 90:91-109.

Goodman LS, Gilman A. 1980.  The pharmacological basis of therapeutics.
6th ed. New York: MacMillan Publishing (cited in EPA 1985a).

Gopinath C, Ford EJH. 1975.  The role of microsomal hydroxylases in the
modification of chloroform and carbon tetrachloride. Toxicol Appl
Pharmacol 63:281-291 (cited in EPA 1985a).

Gosselin RE, Hodge HC, Smith RP, Gleason MN. 1976.  Clinical Toxicology
of Commercial Products. Acute  Poisoning. 4th ed.  Baltimore, HD:
Williams and Wilkins (cited in EPA 1980).

Gram TE, Okine LK, Gram RA.  1986. The metabolism of xenobiotics by
certain extrahepatic organs and its relation to toxicity. Ann Rev
Pharmacol Toxicol 26:259-291.

Hammerstrand K. 1976. Chloroform in drinking water. Varian  Instrum Appl
10:2-4 (cited in IARC 1979).

Hansch C, Leo AJ. 1985. Medchem Project Issue 26.  Claremont CA: Pomona
College.

Hawley GG. 1981. The Condensed Chemical Dictionary. 10th ed. New York:
Van Nostrand Reinhold, p. 237.

Harkov R, Kebbekus B, Bozzelli JU. Lioy PJ, Daisey J. 1984. Comparison
of selected volatile organic compounds during the summer and winter  at
urban sites in New Jersey. Sci Total Environ 38:259-274.

Harris RA, Groh GI.  1985. Membrane disordering effects of anesthetics
are enhanced by gangliosides.  Anesthesiology (USA) 62(2):115-119.

-------
 98   Section 10

 Helz GR, Hsu RY. 1978. Volatile chloro-  and bromocarbons in coastal
 waters. Limnol Oceanogr 23:858-869.

 Heukelekian H, Rand MC. 1955.  Biochemical  oxygen demand of pure organic
 compounds. J Water Pollut Control Assoc  29:1040-1053.

 Hewitt HB. 1956. Renal necrosis in mice  after accidental exposure  to
 chloroform. Br J Exp Pathol 37:32-39.

 Hewitt WR, Miyajima H, Cote KG,  Plaa GC. 1979. Acute alteration of
 chloroform-induced hepato- and nephrotoxicity by Mirex  and Kepone.
 Toxicol Appl Phannacol 48:509-527 (cited in EPA  1985a).

 Hewitt WR, Miyajima H, Cote, MG,  Plaa GC.  1980.  Acute alteration of
 chloroform-induced hepato- and nephrotoxicity by n-hexane,  methyl
 n-butyl ketone and 2,5-hexanedione.  Toxicol Appl Pharmacol 53:230-248
 (cited in EPA 1985a).

 Hewitt WR, Brown EM, Plaa GL.  1983.  Relationship between the  carbon
 skeleton length of ketonic solvents  and  potentiation of  chloroform-
 induced hepatotoxicity in rats. Toxicol  Lett 16:297-304  (cited  in  EPA
 1985a).

 *  Heywood R,  Sortwell  RJ,  Noel PRB,  et al.  1979.  Safety  evaluation of
 toothpaste containing  chloroform.  III. Long-term study  in beagle does
 J  Environ Toxicol 2:835-851.

 *  Hill  RN.  1978.  Differential  toxicity of chloroform in  the mouse   Ann
 NY Acad Sci 298:170-175.

 Hill RN,  Clemson TL, Liu  DK, Vesell  ES, Johnson  WD. 1975.  Genetic
 control  of chloroform  toxicity in mice.  Science  190:159-160.

 Hjelle JJ,  Gordon AS,  Peterson DR. 1982. Studies  on carbon
 tetrachlorideethanol interactions in mice.  Toxicol Lett  10:17-24.

 Hook JB,  Smith JH.  1985.  Biochemical mechanisms  of nephrotoxicity.
 Transplant  Proc  (USA)  17(4 Suppl  1):41-50.

 Hutzler  NJ, Crittenden JC,  Oravitz JL,  Schaepe PA. 1983.  Groundwater
 transport  of chlorinated  organic  compounds.  In:  Proceedings of  the  186th
 National Meeting  of the American  Chemical Society 23:499-502.

 IARC (International Agency for Research on Cancer). 1979.  Chloroform.
 In: Some Halogenated Hydrocarbons. IARC Monographs on the  Evaluation of
 the Carcinogenic  Risk  of Chemicals to Humans. Lyons, France: World
Health Organization, IARC  Vol.  20, pp.  401-427.

 IARC (International  Agency for Research on Cancer). 1982. Chloroform.
 IARC Monographs on  the Evaluation of the Carcinogenic Risk of Chemicals
 to Humans. Lyon,  France: World Health Organization, IARC  Suppl 4.
pp. 87-88.

-------
                                                         References   99

IRPTC (International Register of Potentially Toxic Chemicals). 1987.
IRPTC Data Profile on Chloroform.  Switzerland: United Nations
Environment Programme, April 1987.

Jakobson I, Vahlberg JE, Holmberg B,  Johansson G. 1982. Uptake via the
blood and elimination of 10 organic solvents following epicutaneous
exposure to anesthetized guinea pigs. Toxicol Appl Pharmacol 63:181-187

* Jones WM. Margolis G. Stephen CR. 1958.  Hepatotoxicity of Inhalation
anesthetic drugs. Anesthesiology 19:715.

* Jorgenson TA, Rushbrook CJ.  1980. Effects of Chloroform in the
Drinking Water of Rats and Mice: Ninety-Day Subacute Toxicicy Study
(Final report, Phase 1). EPA-600/1-80-030. NTIS PB80-219108.

* Jorgenson TA, Meierhenry EF,  Rushbrook CJ. et al.  1985.
Carcinogenicity of chloroform in drinking water to male Osborne-Mendel
rats and female B6C3F1 mice. Fund Appl Toxicol (USA) 5(4):760-769.

Kasso WV, Veils MR. 1981. A survey of trihalomethanes in the drinking
water system of Murfreesboro,  Tennessee,  USA. Bull Environ Contain
Toxicol 27:295-302.

Kawamura K, Kaplan IR. 1983. Organic compounds in the rainwater of Los
Angeles. Environ Sci Techno1 17:497-501.

Kawasaki M. 1980. Experiences with the test scheme under the chemical
control law of Japan. An approach to structure-activity correlations
Ecotoxic Environ Safety 4:444-454.

Keith H, Garrison AW, Allen FR, et al. 1976. Identification of organic
compounds in drinking water from thirteen cities. In: Keith LH, ed.
Ident Anal Organic Pollut Water. Ann Arbor, MI: Ann Arbor Press,
pp. 329-373.

Kier LE, Brusick DL, Auletta AE, et al. 1986. The Salmonella
cyphimuri tun/mammalian microsomal assay. A report of the U.S.
Environmental Protection Agency Gene-Tox Program. Mutat Res 168:69-76,
180-184, 202, 206. 207, 216-218, 224-240.
                                                         v.

* Kimura ET, Ebert DM, Dodge BW. 1971. Acute toxicity and limits of
solvent residue for sixteen organic solvents. Toxicol Appl Pharmacol
19:699-704.

Kirkland DJ, Smith KL, Van Abbe NJ. 1981.  Failure of chloroform to
induce chromosome damage or sister-chromatid exchanges in cultured human
lymphocytes and failure to induce reversion in EscherLchia coli. Food
Cosmet Toxicol 19:651-656.

Klaunig JE, Ruch RJ, Pereira MA. 1986. Carcinogenicity of chlorinated
methane and ethane compounds administered in drinking water to mice.
Environ Health Perspect 69:89-95.

-------
 100   Section 10

 Kluwe  WM,  Hook JB.  1978.  Polybrominated blphenyl-induced potentiation of
 chloroform toxictty.  Toxicol Appl  Pharmacol 45:861-869  (cited  in EPA
 1985a).

 Kroneld  R.  1986.  Chloroform in  cap water and human blood. Bull Environ
 Concam Toxicol 36:477-483.

 Krotoszynski  B,  Bruneau GM, O'Neill HJ. 1979. Measunt of chemical
 inhalation exposure in urban populations in the presence of endogeneous
 effluents.  J  Anal Toxicol  3:225-234.

 Kurtz  CM,  Bennett JH.  Shapiro HH.  1936. Electrocardiographic studies
 during surgical  anesthesia. J Am Med Assoc 106:434-441  (cited  in EPA
 1985a).

 Kutob  SD,  Plaa GL.  1962. The effect of acute ethanol intoxication on
 chloroform-induced  liver damage. J Pharmacol Exp Teratol 135:245-251
 (cited in  EPA 1985a).

 * Kylin  B,  Reichard H,  Sumegi I, Yllner S.  1963. Hepatotoxicity of
 inhaled  trichloroethylene. tetrachloroethylene, and chloroform. Single
 exposure. Acta Pharmacol Toxicol 20:16-26.

 * Land PD,  Owen  EL, Linde HW. 1981. Morphologic changes in mouse
 spermatozoa after exposure to inhalational anesthetics during early
 spermatogenesis.  Anesthesiology 54:53-56.

 Lehmann  KB, Flury FF.  1943. Chlorinated hydrocarbons. In: Lehman KB,
 Flury  FF, eds. Toxicology and Hygiene of Industrial Solvents. Baltimore,
 MD: Williams  and  Wilkins, pp. 138-145 and 191-196 (cited in EPA 1985a)

 * Lehmann KB,  Hasewaga. 1910. Studies of the absorption of chlorinated
 hydrocarbons  in animals and humans. Arch Hyg 72:327 (FRG) (cited in EPA
 1985a).

 * Lehmann KB.  Schmidt-Kehl L. 1936. The thirteen most important
 chlorinated aliphatic hydrocarbons from the standpoint of industrial
 hygiene. Arch Hyg 116:131-200 (FRG) (cited in NIOSH 1974, EPA 1985a).

 Liang  JC, Hsu TC, Henry JE. 1983. Cytogenetic assays for mitotic
 poisons: The  grasshopper embryo system for volatile liquids. Mutat Res
 113:467-479.

 Lovegren NV,  Fisher GS, Legendre MG, Schuller WH. 1979. Volatile
 constituents  of dried  legumes. J Agric Food Chem 27:851-853.

 * Lundberg I,  Ekdahl M, Kronevi T. Lidums V, Lundberg S. 1986. Relative
hepatotoxicity of some  industrial solvents  after intraperitoneal
 injection or  inhalation exposure to rats.  Environ Res 40(2):411-420.

Mabey W,  Mill  T.  1978. Critical review of hydrolysis of organic
compounds in water  under environmental conditions. J Phys Chem Ref Data
 7:383-415.

-------
                                                        References   101

Masuda Y, Nakayama N.  1982.  Protective effect of diethyldlthiocarbamate
and carbon disulflde against liver injury induced by various hepatotoxic
agents. Biochem Pharmacol 31:2713-2725 (cited in EPA 1985a).

Masuda Y, Nakayama N.  1983.  Protective action of diethyldithiocarbamate
and carbon disulfide" against renal injury induced by chloroform in mice
Biochem Pharmacol 31:2713-2725 (cited in EPA 1985a).

McConnell G. Ferguson DM. Pearson CR. 1975.  Chlorinated hydrocarbons and
the environment. Endeavor 34:13-18.

McMartin ND, O'Connor JA Jr, Kaminsky LS.  1981.  Effect of differential
changes in rat hepatic and renal cytochrome  P-450 concentrations on
hepatotoxicity and nephrotoxicity of chloroform. Res Commun Chem Pathol
Pharmacol 31:99-110.

Mink FL, Brown TJ, Rickabaugh J. 1986. Absorption, distribution, and
excretion of carbon-14 trihalomethanes in mice and rats.-Bull Environ
Contam Toxicol 37(5):752-758.

Mirsalis JC, Tyson CK, Butterworth BE. 1982. Detection of genotoxic
carcinogens in the in vivo--in vitro hepatocyte DNA repair assay.
Environ Mutagenesis 4:553-562.

* Moore DH, Chasseaud LF, Majeed SK, Prentice DE, Roe FJC, Van abbe NJ.
1982. The effect of dose and vehicle on early tissue damage and
regenerative activity after chloroform administration to mice. Food Chem
Toxicol 20:951-954.

Morimoto K, Koizumi A. 1983. Trihalomethanes-induced sister chromatid
exchanges in human lymphocytes in vitro and mouse bone marrow cells in
vivo. Environ Res 32(1):72-79.

Morris LEV. 1951. Chloroform in blood and respired atmosphere. In:
Chloroform, A Study After 100 Years. Madison, WI: University of
Wisconsin Press, pp. 95-119 (cited in EPA 1985a).

Munson AE, Sain LE, Sanders VM, et al. 1982. Toxicology of organic
drinking water contaminants: Trichloromethane, bromodichloromethane,
dibromochloromethane, and tribromoethane. Environ Health'Perspect
46:117-126.

* Murray FJ, Schwetz BA, McBride JG, Staples RE. 1979. Toxicity  of
inhaled chloroform in pregnant mice and their offspring. Toxicol Appl
Pharmacol 50:515-522.

NAS  (National Academy of Sciences). 1977. Drinking Water and Health.
Vol. 1. Washington, DC: National Academy of Sciences, pp.  713-718.

* NCI  (National Cancer Institute). 1976. Report  on Carcinogenesis
Bioassay of Chloroform. NTIS PB-264018.

-------
  102   Section 10
 Newberne PM, Welgert J, Kula N. 1979. Effects of dietary fat on hepat
 mixed function oxidases and hepatocellular carcinoma induced by
 aflatoxin Bl in rats. Cancer Res 39:3986-3991.
1C
 Newberne PM, Decamargo JLV, Clarke A.  1982.  Choline deficiency,  partial
 hepatectomy, and liver tumors in rats  and mice.  Toxicol Pathol 10:95-109
 (cited in Jorgenson et al. 1985).

 Nicholson AA, Heresz 0, Lemyk B.  1977.  Determination of free and total
 potential halofonns in drinking water.  Anal  Chem 49:814-819.

 Nicholson BC, Maguire BP,  Bursill DB.  1984.  Henry's Law constants for
 the trihalomethanes: Effects of water  composition and temperature
 Environ Sci Technol 18:518-521.

 * NIOSH (National Institute for Occupational Safety and Health).  1974
 Criteria for a Recommended Standard...Occupational Exposure  to
 Chloroform.  NTIS PB-246-695 (cited in  EPA 1985a).

 NIOSH (National Institute  for Occupational Safety and Health). 1987c
 NIOSH Manual of Analytical Methods.  3rd ed.  Vol.  2.  Cincinnati,  OH:
 Department  of Health and Human Services.   DHHS  (NIOSH)  Publ  84-100
 Revision 1,  8/15/87.

 NIOSH (National Institute  for Occupational Safety and Health). 1977.
 National  Occupational  Hazard Survey. Vol.  14. Survey Analyses  and
 Supplemental Tables.  Cincinnati,  OH: Department of Health, Education
 and Welfare,  pp.  2864-2866 (cited in EPA 1985a).

 NIOSH (National Institute  for Occupational Safety and Health). 1984
 Current Awareness File.  Registry  of Toxic  Effects  of Chemical  Substances
 (RTECS).  Cincinnati, OH: National Institute  for Occupational Safety and
 Health.

 NIOSH (National Institute  for Occupational Safety  and Health). 1987a.
 RTECS  (Registry of  Toxic Effects  of Chemical Substances). Chloroform   On
 line, January 1987.

 NLM  (National Library  of Medicine). 1987.  Hazardous  Substance  Data Bank
 Chloroform Record No.  56 (computer printout).

 NTIS  (National  Technical Information Service). 1987.  Federal Research  in
 Progress. On  line,  March 1987  (Dialog File 265).

 NTP  (National Toxicology Program). 1986. Annual Plan  for Fiscal Year
 1986.  Research Triangle Park, NC: National Toxicology Program. Public
 Health Service, Department of Health and Human Services, pp.  49   50
 181. NTP-86-086.

NYDEC (New York State  Department  of Environmental Conservation).   1985
 Superfund and Contract Laboratory Protocol, January  1985. NYDEC.
pp. D-54 to D-95.

-------
                                                        References   102

Orth OS, Liebenow RR, Capps RT.  1951.  III-The effect of chloroform on
the cardiovascular system.  In:  Waters  RM,  ed.  Chloroform, A Study After
100 Years.  Madison,  WI:  University of Wisconsin Press, pp. 39-75 (cicec
in EPA 1985a).

OSHA (Occupational Safety and Health Administration). 1985. Permissible
Exposure Limits. Code of Federal Regulations 29:1910.1000.

* Palmer AK, Street AE, Roe FJC, Worden AN.  Van Abbe NJ.  1979.  Safety
evaluation of toothpaste containing chloroform. II. Long-term studies ir
rats. J Environ Pathol Toxicol 2:821-833.

Parsons JS, Mitzner S. 1975.  Gas chromatographic method for
concentration and analysis  of traces of industrial organic pollutants ir.
environmental air and stacks. Environ  Sci  Techno1 9:1053-1058.

Paul BB, Rubinstein D. 1963.  Metabolism of carbon tetrachloride and
chloroform by the rat. J Pharmacol Exp Ther 141:141-148.

Pellizzari ED, Hartwell TD, Harris BSH, et al. 1982. Purgeable organic
compounds in mother's milk. Bull Environ Contain Toxicol 28:322-328.

Peoples AJ, Pfaffenberger CD, Shafik TM, Enos HF. 1979. Determination of
volatile purgeable halogenated hydrocarbons in human adipose tissue and
blood serum. Bull Environ Contam Toxicol 23:244-249.

Pereira MA, Lin LC, Lippitt JM,  Herren SL. 1982. Trihalomethanes as
initiators and promoters of carcinogenesis.  Environ Health Perspect
46:151-156.

Pereira MA, Daniel FB, Lin E. 1985. Relationship between metabolism of
haloacetonitriles and chloroform and their carcinogenic activity. In:
Jolley RL, et al., ed. Water Chlorination. Vol. 5. Chemistry,
Environmental Impact and Health Effects. Chelsea, MI: Lewis Publishers.

Pfaffenberger CD, Peoples AJ, Enos HF. 1980. Distribution of volatile
halogenated organic compounds between rat blood serum and adipose
tissue. Intern J Environ Anal Chem 8:55-65.
                                                         ',
* Phoon WH, Goh KT. Lee LT, Tan KT, Kwok SE. 1983. Toxic jaundice from
occupational exposure to chloroform. Med J Malaysia 30:31-34.

Pohl LR, Gillette JR. 1984. Determination of toxic pathways of
metabolism by deuterium substitution.  Drug Metab Rev (USA)
15(7):1335-1351.

Pohl LR, George JW, Satoh H. 1984. Strain and sex differences in
chloroform-induced nephrotoxicity. Different rates of metabolism of
chloroform to phosgene by the mouse kidney. Drug Metab Dispos
12(3):304-308.

-------
 104    Section  20

 Premel-Cabic A. Cailleux A,  Allain P. 1974. A gas chromatographic assay
 of fifteen volatile  organic  solvents in blood. Clin Chim Acta 56:5-11
 (French)  (cited in  IARC 1979).

 Rao  PSC,  Hornsby AG, Jessup  RE.  1985. Indices for ranking the potential
 for  pesticide  contamination  of groundwater. Soil Crop Sci Soc Fl Proc
 44-1-8.

 Rachbun RE, Tai DY.  1981. Technique for determining the volatilization
 coefficients of priority pollutants in streams. Water Res 15:243-250.

 Rehm RM,  Anderson ME. Duletsky SA, Misenheimer DC, Rollius HF.' 1982.
 Chloroform Materials Balance.  Draft report. EPA Contract 68-02-3168.
 Task 69 (cited in EPA 1985a).

 Reitz  RH,  Quast JF, Scott WT, Watanabe PG, Behring OJ. 1980.
 Pharmacokinetics and macromolecular effects of chloroform in rats and
 mice.  Implications for carcinogenic risk estimation. Water Chlorinat
 Environ Impact Health Eff 3:983-993.

 Reitz  RH,  Fox  TR, Quast JF.  1982. Mechanistic considerations for
 carcinogenic risk estimation: Chloroform.  Environ Health Perspect
 46:163-168.

 Reunanen M, Kroneld R. 1982. Determination of volatile halocarbons in
 raw  and drinking water, human serum,  and urine by electron capture GC.
 J Chromatogr Sci 20:449-454.

 Reynolds ES. 1967. Liver parenchymal cell  injury. IV. Pattern of
 incorporation  of carbon and  chlorine from carbon tetrachloride into
 chemical constituents of liver in vivo.  J  Pharmacol Exp Ther
 155:177-126.

 Reynolds ES. 1977. Liver endoplasmic reticulum. Target site of
halomethane metabolism. Adv  Exp Med Biol 84:117.

Reynolds ES, Yee AG. 1967. Liver parenchymal cell injury. V.
Relationships between patterns of chloromethane--l^C incorporation into
constituents of liver in vivo and cellular injury. Lab Invest
 16:591-603.

* Reynolds ES,  Trelnen RJ, Farrish HH,  Moslen MT. 1984a. Relationships
between the pharmacokinetics of carbon tetrachloride conversion to
carbon dioxide and chloroform and liver injury. Arch Toxicol 7:303-306
 (cited in EPA  1985a).

Reynolds ES, Treinen RJ, Farrish HH,  Moslen MT. 1984b. Metabolism of
14C-carbon tetrachloride to exhaled,  excreted, and bound metabolites.
Dose-response,  time-course, and pharmacokinetics. Biochem Pharmacol
33:3363-3374.

-------
                                                        References   105

* Roe FJC, Palmer AAK,  Worden AN,  Van Abbe NJ.  1979.  Safety evaluation
of toothpaste containing chloroform.  I.  Long-term studies in mice. J
Environ Toxicol 2:799-819.

Roberts PV. Schreiner J. Hopkins GD.  1982. Field study of organic water
quality changes during groundwater recharge in the Palo Alto Baylands.
Water Res 16:1025-1035.

Rosenthal SL. 1987.  A review of the mutagenicity of chloroform.  Environ
Molec Hutagenesis 10:211-226.

Rubinstein D, Kanics L. 1964. The conversion of carbon tetrachloride and
chloroform to carbon dioxide by rat liver homogenates. Can J Biochem
42:1577-1585.

Rudali G. 1967. Oncogenic activity of some halogenated hydrocarbons used
in therapeutics. UICC Monogr Ser 7:138-143 (cited in EPA 1985a).

Sato A, Nakajima T.  1984. Dietary carbohydrate-induced and ethanol-
induced alteration of the metabolism and toxicity of chemical
substances. Nutr Cancer 6:121-132 (cited in EPA 1985a).

Sato A, Nakajima T,  Koyama Y. 1980. Effects of chronic ethanol
consumption on hepatic metabolism of aromatic and chlorinated
hydrocarbons in rats. Br J Indust Med 37:382-386 (cited in EPA 1985a).

Sato A, Nakajima T,  Koyama Y. 1981. Dose-related effect of a single dose
of ethanol on the metabolism in rat liver of some aromatic and
chlorinated hydrocarbons. Toxicol Appl Pharmacol 60:8-15 (cited in EPA
1985a).

Sax NI. 1979. Dangerous properties of industrial materials. 5th ed. New
York: Van Nostrand Reinhold, p. 193 (cited in EPA 1985a).

Scholler KL. 1970. Modification of the effects of chloroform on the rat
liver. Br J Anaesth 42:603-605 (cited in  EPA 1985a).

* Schroeder HG. 1965. Acute and delayed chloroform poisoning. A case
report. Br J Anaesth 37:972-975.

* Schwetz BA, Leong BKJ, Gehring PJ. 1974. Embryo and fetotoxicity of
inhaled chloroform in rats. Toxicol Appl  Pharmacol 28:442-451.

Shubik P, Ritchie AL. 1953. Sensitivity of male DBA mice to the  toxicity
of chloroform as a laboratory hazard. Science 17:285  (cited in EPA
1985a).

Simmon VF, Kauhanen K,  Tardiff RG. 1977.  Mutagenic activity of chemicals
identified in drinking  water. In:  Scott D, Bridges BA,  Sobels FH,  eds.
Progress  in Genetic Toxicology. Elsevier/North Holland  Press,
pp. 249-258.

-------
  106   Section  10

  Singh HB, Salas LJ, Stiles RE. 1982. Distribution of selected gaseous
  organic mutagens and suspect carcinogens in ambient air.  In:  Proceedings
  of the Annual  Meeting of the Air Pollution Control Association
  75(4):82-65.1.

  Single/ JE. 1984. Water (municipal treatment).  In: Grayson M.  Eckroth D
  eds. Kirk-Othmer Encyclopedia of Chemical Technology,  3rd ed.  Vol 24
  New York: John Wiley and Sons, pp. 385-406.

  Sipes IG, Krishna G, Gillette JR.  1977.  Bioactivation  of  carbon
  tetrachloride, chloroform,  and bromotrichloromethane.  Role of  cytochroire
  P-450. Life Sci 20:1541-1548.

 * Smith AA,  Volpitto PO, Gramling ZW,  DeVore  MB,  Classman AB.   1973.
 Chloroform,  halothane,  and regional anesthesia. A comparative  study
 Anesth Analg (Cleveland) 52:1-11.

 Smith JH,  Hook JB.  1983. Mechanism of  chloroform  nephrotoxicity.  II   In
 vitro evidence for renal metabolism of chloroform in mice.  Toxicol ADD!
 Pharmacol 70(3):480-485.

 Smith JH,  Hook JB.  1984. Mechanism of  chloroform  nephrotoxicity.  III.
 Renal and hepatic mlcrosomal  metabolism  of chloroform  In  mice   Toxicol
 Appl  Pharmacol 73(3):511-524.

 Smith JH,  Malta K,  Sleight  SD,  Hook JB.  1984. Effect of sex hormone
 status on chloroform nephrotoxicity and  renal mixed  function oxidases  in
 mice.  Toxicology 30(4):305-316.

 Smyth HF,  Carpenter CP.  Well  CS, Pozzani UC, Striegel JA.  1962. Range
 finding  toxiclty data:  List VI. Am Ind Hyg Assoc  J 23:95-107.

 Sporstoel  S, Urdal  K, Drangsholt H,  GJoes N. 1985. Description  of a
 method for automated determination of  organic pollutants  in water  Inc  J
 Environ Anal Chem 21:129-138.

 SRI (Stanford  Research  Institute)   1987. Directory of Chemical
 Producers: United States of America. Menlo Park,  CA: SRI  International

 Steward A, Allot PR, Cowles AL, Mapleson WW. 1973. Solubility
 coefficients for Inhaled anaesthetics  for water,  oil, and biological
 media. Br  J Anaesth 45:282-293.

 Stewart RD. Dodd HC, Erly DS, Holder BB. 1965. Diagnosis  of solvent
 poisoning. J Am Med Assoc 193:1097-1100.

 Strachan WMJ, Edwards CJ. 1984. Organic pollutants In Lake  Ontario. Adv
 Environ Scl Technol  14:239-264.

 Sturrock J. 1977. Lack of mutagenic effect of halothane or  chloroform on
cultured cells  using the azaguanine  test system.  Br J Anaesth
49:207-210.

-------
                                                        References   10"

Symons JM, Bellar TA, Carswell JK, et al. 1975. National Organic
Reconnaissance Survey for halogenated organics. J An Water Works Assoc
67:634-647.

Tabak HH, Quave SA, Hashni CI, Barth EF.  1981. Biodegradability studies
with organic priority pollutant compounds.  J Water Pollut Control Fed
53:1503-1518.

Taylor DC, Brown DM, Kuble R, Langley PF. 1974. Metabolism of
chloroform. II. A sex difference in the metabolism of ^C-chloroform ir
mice. Xenobiotica 4:165-174.

* Thompson DJ,  Warnet SD, Robinson W.  1974. Teratology studies on
orally administered chloroform in the rat and rabbit. Toxicol Appl
Pharmacol 29:348-357.

Topham JC. 1980. Do induced sperm-head abnormalities in mice
specifically identify mammalian mutagens rather than carcinogens?  Mucac
Res 74:379-387.

* Torkelson TR, Oyen F,  Rove VK. 1976.  The toxicity of chloroform as
determined by single and repeated exposure of laboratory animals. Am Ind
Hyg Assoc J 37:697-704.

Tsurata H. 1975. Percutaneous absorption of organic solvents. 1.
Comparative study of the in vivo percutaneous absorption of chlorinated
solvents in mice. Ind Health 13:227-236.

Tsurata H. 1977. Percutaneous absorption of organic solvents. 2. A
method for measuring the penetration rate of chlorinated solvents
through excised rat skin. Ind Health 15:131-140.

Tumasonis CF, McMartin DN, Bush B. 1985.  Lifetime toxicity of chloroform
and bromodichloromethane when administered over a lifetime in rats.
Ecotoxicol Environ Saf 9(2):233-240.

Uehleke H,.Werner T. 1975. A comparative study on the irreversible
binding of labeled halothane, trichlorofluoromethane, chloroform, and
carbon tetrachloride to hepatic protein and lipids in vitro and  in vivo
Arch Toxicol 34:289-303 (cited in EPA 1985).

Uehleke H, Werner T, Greim H, Kramer M. 1977. Metabolic activation of
halothane and tests in vitro for mutagenicity. Xenobiotica 7:393-400

USITC (United States International Trade Commission). 1986. Synthetic
Organic Chemicals, United States Production and Sales, 1985. USITC
Publication 1892. Washington DC: USITC.

Van Dyke RA, Chenoweth MB, Van Poznak A. 1964. Metabolism of volatile
anaesthetics. I. Conversion in vivo of several anesthetics to ^C02 and
chloride. Blochem Pharmacol 13:1239-1247.

-------
 108   Section  10

 Varma MM, Balram A. Katz HM. 1984. Trihalomethanes in groundwater
 systems. J Environ Syst 14(2):115-126.

 Veiro JA, Hunt GRA. 1985. The modulation of ion channels by the
 inhalation of  general anaesthetics. A supplemental 1H-NMR investigation
 using unilamellar phospholipid membranes  Chem Biol Interact (Ireland)
 54(3)-337-348.

 Von Oettingen WF. 1955. The halogenated hydrocarbons toxicity and
 potential dangers. Washington, DC: U.S. Department of Health, Education,
 and Welfare, Government Printing Office (cited in EPA 1980).

 Von Oettingen WF. 1964. The Halogenated Hydrocarbons of Industrial and
 Toxicological  Importance. Amsterdam: Elsevier, pp. 77-108 (cited in EPA
 1985a).

 * Wallace CJ.  1950. Hepatitis and nephrosis due to cough syrup
 containing chloroform. Calif Med 73:442.

 Wallace LA.  1986. Personal exposures, indoor and outdoor air
 concentrations, and exhaled breath concentrations of selected volatile
 organic compounds measured for 600 residents of New Jersey, North
 Dakota, North Carolina, and California. Toxicol Environ Chem
 612:215-236.

 Wallace L, Pellizzari E, Hartwell T, et al. 1986a. Concentrations of 20
 volatile organic compounds in the air and drinking water of 350
 residents of New Jersey compared with concentrations in their exhaled
 breath. J Occup Med 28:603-607.

 Wallace L, Pellizzari E, Sheldon L, Hartwell T, Sparacino C, Zelon H
 1986b. The total exposure assessment methodology (TEAM) study: Direct
 measurement of personal exposures through air and water for 600
 residents of several cities. In: Cohen Y, ed. Pollutants in Multimedia
 Environment. Plenum Publishing,  pp. 289-315.

Wallace L, Pellizzari E, Leaderer B, Zelon H, Sheldon L. 1987. Emissions
of volatile organic compounds from building material and consumer
products. Atmos Environ 21:385-395.

White AE, Takehisa S, Eger El,  Wolff S, Stevens WC. 1979. Sister
chromatid exchanges induced by inhaled anesthetics. Anesthesiology
 50:426-430 (cited in EPA 1985a).

Wilson J, Enfield CG, Dunlap VJ, Cosby RL, Foster DA, Baskin LB. 1981.
Transport and fate of selected organic pollutants in a sandy soil. J
 Environ Qual 10:501-506.

Wilson JT, MeNabb JF, Wilson BH, Noonan MJ. 1983. Biotransformation of
 selected organic pollutants in groundwater. Dev Ind Microbiol
 24:225-233.

-------
                                                         References    109

Windholz M,  ed.  1983. The Merck  Index.  10th ed. Rahway,  NJ:  Merck and
Co., pp. 300-301.

Withey JR. Collins BT, Collins PG. 1983. Effect of vehicle on  the
pharmacokinetics and uptake of four halogenated hydrocarbons from the
gastrointestinal tract of the rat. J Appl Toxicol 3:249-253.

Wolf CR. Mansuy D, Nastainczyk W, Deutschmann G. Ullrich V.  1977. The
reduction of polyhalogenated methanes by liver microsomal cytochrome
P-450. Mol Pharmacol 13:698-705  (cited  in EPA 1985a).

Wood-Smith FG, Stewart HC. 1964.  Drugs  in Anesthetic Practice.
Washington,  DC: Butterworth, pp.  131-135 (cited in EPA 1985a).

Young TB, Kanarek MS, Tslatis AA. 1981. Epidemiologic study of drinking
water chlorination, Wisconsin female cancer mortality. J Natl Cancer
Inst 67(6):1191-1198.

Zeller A. 1883. On the fate of iodoforms and chloroform  in the organism
Hoppe-Seyler's Z Physiol Chem 8:78-79 (cited in EPA 1985a).

Zoeteman BCJ, Harmsen K,  Linders  JBHJ,  Morra CFH,  Sloof W. 1980.
Persistent organic pollutants in  river water and groundwater of the
Netherlands.  Chemosphere 9:231-249.

-------
                                                                     ILL
                             11.   GLOSSARY

Acute Exposure--Exposure to a chemical for a duration of 14 days or
less, as specified in the Toxicological Profiles.

Bioconcentration Factor (BCF)--The quotient of the concentration of a
chemical in aquatic organisms at  a specific time or during a discrete
time period of exposure divided by the concentration in the surrounding
water at the same time or during  the same time period.

Carcinogen--A chemical capable of inducing cancer.

Ceiling value (CL)--A concentration of a substance that should not be
exceeded, even instantaneously.

Chronic Exposure--Exposure to a chemical for 365 days or more, as
specified in the Toxicological Profiles.

Developmental Toxicity--The occurrence of adverse effects on the
developing organism that may result from exposure to a chemical prior co
conception (either parent), during prenatal development, or postnatally
to the time of sexual maturation. Adverse developmental effects may be
detected at any point in the life span of the organism.

Embryotoxicity and Fetotoxicity--Any toxic effect on the conceptus as a
result of prenatal exposure to a  chemical; the distinguishing feature
between the two terms is the stage of development during which the
insult occurred. The terms, as used here, include malformations and
variations, altered growth, and in utero death.

Frank Effect Level (FEL)--That level of exposure which produces a
statistically or biologically significant increase in frequency or
severity of unmistakable adverse  effects, such as irreversible
functional impairment or mortality, in an exposed population when
compared with its appropriate control.

EPA Health Advisory--An estimate  of acceptable drinking water levels for
a chemical substance based on health effects information. A health
advisory is not a legally enforceable federal standard, but serves as
technical guidance to assist federal, state, and local officials.

Immediately Dangerous to Life or  Health (IDLH)--The maximum
environmental concentration of a  contaminant from which one could escape
within 30 min without any escape-impairing symptoms or irreversible
health effects.

-------
 112   Section 11

 Intermediate Exposure--Exposure to a chemical for a duration of 15-36u
 days, as specified in the Toxicological Profiles.

 Immunologic Toxicity--The occurrence of adverse effects on the immune
 system that may result from exposure to environmental agents such as
 chemicals.

 In vitro--Isolated from the living organism and artificially maincair.ec.
 as in a test tube.

 In vivo--Occurring within the living organism.

 Key Study--An animal  or human toxicological study that best  illustrates
 the nature  of the adverse effects  produced  and  the  doses  associated  with
 those effects.

 Lethal Concentration(LO)  (LCLO)--The lowest concentration of a chemical
 in air which has been reported to  have  caused death in humans or
 animals.

 Lethal Concentration^)  
-------
                                                           Glossary    113

 Neurotoxicity--The  occurrence  of  adverse  effects  on the  nervous  system
 following exposure  to  a  chemical.

 No -Observed -Adverse -Effect Level  (NOAEL)--That  dose of chemical  at which
 there  are no  statistically or  biologically  significant increases in
 frequency or  severity  of adverse  effects  seen between  the  exposed
 population and  its  appropriate control. Effects may be produced  at this
 dose,  but they  are  not considered to be adverse.

 No-Observed-Effect  Level (NOEL) --That dose  of chemical at  which  there
 are  no statistically or  biologically significant  increases in  frequency
 or severity of  effects seen between the exposed population and its
 appropriate control.

 Permissible Exposure Limit (PEL) --An allowable  exposure  level  in
 workplace air averaged over an 8-h shift.

 q^ --The  upper-bound estimate  of  the low-dose slope of the dose-response
 curve  as  determined by the multistage procedure. The q * can be  used  to
 calculate an estimate  of carcinogenic potency,  the  incremental excess
 cancer risk per unit of  exposure  (usually /ig/L  for  water,  mg/kg/day for
 food,  and Mg/n^ for air) .
Reference Dose (RfD)--An estimate (with uncertainty spanning perhaps an
order of magnitude) of the daily exposure of the human population to a
potential hazard that is likely to be without risk of deleterious
effects during a lifetime. The RfD is operationally derived from the
NOAEL (from animal and human studies) by a consistent application of
uncertainty factors that reflect various types of data used to estimate
RfDs and an additional modifying factor, which is based on a
professional judgment of the entire database on the chemical. The RfDs
are not applicable to nonthreshold effects such as cancer.

Reportable Quantity (RQ)--The quantity of a hazardous substance that is
considered reportable under CERCLA.  Reportable quantities are: (1) 1 Ib
or greater or (2) for selected substances, an amount established by
regulation either under CERCLA or under Sect. 311 of the Clean Water
Act. Quantities are measured over a 24 -h period.

Reproductive Toxiclty--The occurrence of adverse effects on the
reproductive system that may result from exposure to a chemical. The
toxic ity may be directed to the reproductive organs and/or the related
endocrine system. The manifestation of such toxicity may be noted as
alterations in sexual behavior, fertility, pregnancy outcomes, or
modifications in other functions that are dependent on the integrity of
this system.

Short-Term Exposure Limit (STEL)--The maximum concentration to which
workers can be exposed for up to 15 min continually. No more than four
excursions are allowed per day, and there must be at least 60 min
between exposure periods. The daily TLV-TWA may not be exceeded.

-------
 114   Section 11

 Target Organ Toxlcity--This  term covers  a broad  range  of adverse effects
 on target organs  or physiological systems (e.g.,  renal,  cardiovascular)
 extending from those arising through  a single  limited  exposure  to those
 assumed over a lifetime pf exposure to a chemical.

 Teratogen--A chemical that causes structural defects that affect the
 development  of an organism.

 Threshold Limit Value (TLV)--A concentration of a substance  to  which
 most workers  can  be exposed  without adverse effect. The  TLV  may be
 expressed as  a TWA,  as  a STEL, or as  a CL.

 Time-weighted  Average (TWA)--An  allowable exposure concentration
 averaged  over  a normal  8-h workday or 40-h workweek.

 Uncertainty Factor  (UF)--A factor used in operationally  deriving the RfD
 from experimental data.  UFs  are  intended to account for  (1)  the
variation  in sensitivity among the members of the human  population,
 (2) the uncertainty  in  extrapolating animal data to the  case of  humans.
 (3) the uncertainty  in  extrapolating from data obtained  in a study that
 is of less than lifetime exposure, and (4) the uncertainty in using
LOAEL data rather than  NOAEL data. Usually each of these  factors  is set
equal to 10.

-------
                                                                     LL5
                         APPENDIX:   PEER REVIEW

     A peer review panel was assembled for chloroform.  The panel
consisted of the following 'members:  Dr.  Herbert Cornish,  (retired)
Professor of Toxicology, University of Michigan;  Dr.  Derek Hodgson,
Vice Chairman, Department of Chemistry,  University of North Carolina,
Chapel Hill; and Dr.  Richard Bull,  Associate Professor of
Pharmacology/Toxicology, College of Pharmacy,  Washington State
University. These experts collectively have knowledge of chloroform's
physical and chemical properties, toxicokinetics,  key health end points,
mechanisms of action, human and animal exposure,  and quantification of
risk to humans. All reviewers were selected in conformity with the
conditions for peer review specified in the Superfund Amendments and
Reauthorization Act of 1986, Section 110.

     A joint panel of scientists from ATSDR and EPA has reviewed the
peer reviewers' comments and determined which comments will be included
in the profile. A listing of the peer reviewers'  comments not
incorporated in the profile, with a brief explanation of the rationale
for their exclusion,  exists as part of the administrative record for
this compound. A list of databases reviewed and a list of unpublished
documents cited are also included in the administrative record.

     The citation of the peer review panel should not be understood to
imply their approval of the profile's final content.  The responsibility
for the content of this profile lies with the Agency for Toxic
Substances and Disease Registry.

-------