#ls ¦¦¦¦¦ifcSE United States
¦¦¦¦BiiiiH Environmental Protection
1=1 JF m Agency
EPA/690/R-04/004F
Final
11-24-2004
Provisional Peer Reviewed Toxicity Values for
Chloroacetic Acid
(CASRN 79-11-8)
Superfund Health Risk Technical Support Center
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268

-------
Acronyms
bw - body weight
cc - cubic centimeters
CD - Caesarean Delivered
CERCLA - Comprehensive Environmental Response, Compensation, and Liability Act of 1980
CNS - central nervous system
cu.m - cubic meter
DWEL - Drinking Water Equivalent Level
FEL - frank-effect level
FIFRA - Federal Insecticide, Fungicide, and Rodenticide Act
g - grams
GI - gastrointestinal
HEC - human equivalent concentration
Hgb - hemoglobin
i.m. - intramuscular
i.p. - intraperitoneal
i.v. - intravenous
IRIS - Integrated Risk Information System
IUR - Inhalation Unit Risk
kg - kilogram
L - liter
LEL - lowest-effect level
LOAEL - lowest-observed-adverse-effect level
LOAEL(ADJ) - LOAEL adjusted to continuous exposure duration
LOAEL(HEC) - LOAEL adjusted for dosimetric differences across species to a human
m - meter
MCL - maximum contaminant level
MCLG - maximum contaminant level goal
MF - modifying factor
mg - milligram
mg/kg - milligrams per kilogram
mg/L - milligrams per liter
MRL - minimal risk level
MTD - maximum tolerated dose
1

-------
MTL - median threshold limit
NAAQS - National Ambient Air Quality Standards
NOAEL - no-observed-adverse-effect level
NOAEL(ADJ) - NOAEL adjusted to continuous exposure duration
NOAEL(HEC) - NOAEL adjusted for dosimetric differences across species to a human
NOEL - no-observed-effect level
OSF - Oral Slope Factor
p-RfD - provisional Oral Reference Dose
p-RfC - provisional Inhalation Reference Concentration
p-OSF - provisional Oral Slope Factor
p-IUR - provisional Inhalation Unit Risk
PBPK - physiologically based pharmacokinetic
ppb - parts per billion
ppm - parts per million
PPRTV - Provisional Peer Reviewed Toxicity Value
RBC - red blood cell(s)
RCRA - Resource Conservation and Recovery Act
RGDR - Regional deposited dose ratio (for the indicated lung region)
REL - relative exposure level
RGDR - Regional gas dose ratio (for the indicated lung region)
RfD - Oral Reference Dose
RfC - Inhalation Reference Concentration
s.c. - subcutaneous
SCE - sister chromatid exchange
SDWA - Safe Drinking Water Act
sq.cm. - square centimeters
TSCA - Toxic Substances Control Act
UF - uncertainty factor
ug - microgram
umol - micromoles
VOC - volatile organic compound
11

-------
11-24-2004
PROVISIONAL PEER REVIEWED TOXICITY VALUES FOR
CHLOROACETIC ACID (CASRN 79-11-8)
Background
On December 5, 2003, the U.S. Environmental Protection Agency's (EPA's) Office of
Superfund Remediation and Technology Innovation (OSRTI) revised its hierarchy of human
health toxicity values for Superfund risk assessments, establishing the following three tiers as the
new hierarchy:
1.	EPA's Integrated Risk Information System (IRIS).
2.	Provisional Peer-Reviewed Toxicity Values (PPRTV) used in EPA's Superfund
Program.
3.	Other (peer-reviewed) toxicity values, including:
~	Minimal Risk Levels produced by the Agency for Toxic Substances and Disease
Registry (ATSDR),
~	California Environmental Protection Agency (CalEPA) values, and
~	EPA Health Effects Assessment Summary Table (HEAST) values.
A PPRTV is defined as a toxicity value derived for use in the Superfund Program when
such a value is not available in EPA's Integrated Risk Information System (IRIS). PPRTVs are
developed according to a Standard Operating Procedure (SOP) and are derived after a review of
the relevant scientific literature using the same methods, sources of data, and Agency guidance
for value derivation generally used by the EPA IRIS Program. All provisional toxicity values
receive internal review by two EPA scientists and external peer review by three independently
selected scientific experts. PPRTVs differ from IRIS values in that PPRTVs do not receive the
multi-program consensus review provided for IRIS values. This is because IRIS values are
generally intended to be used in all EPA programs, while PPRTVs are developed specifically for
the Superfund Program.
Because science and available information evolve, PPRTVs are initially derived with a
three-year life-cycle. However, EPA Regions (or the EPA HQ Superfund Program) sometimes
request that a frequently used PPRTV be reassessed. Once an IRIS value for a specific chemical
becomes available for Agency review, the analogous PPRTV for that same chemical is retired. It
should also be noted that some PPRTV manuscripts conclude that a PPRTV cannot be derived
based on inadequate data.
1

-------
11-24-2004
Disclaimers
Users of this document should first check to see if any IRIS values exist for the chemical
of concern before proceeding to use a PPRTV. If no IRIS value is available, staff in the regional
Superfund and RCRA program offices are advised to carefully review the information provided
in this document to ensure that the PPRTVs used are appropriate for the types of exposures and
circumstances at the Superfund site or RCRA facility in question. PPRTVs are periodically
updated; therefore, users should ensure that the values contained in the PPRTV are current at the
time of use.
It is important to remember that a provisional value alone tells very little about the
adverse effects of a chemical or the quality of evidence on which the value is based. Therefore,
users are strongly encouraged to read the entire PPRTV manuscript and understand the strengths
and limitations of the derived provisional values. PPRTVs are developed by the EPA Office of
Research and Development's National Center for Environmental Assessment, Superfund Health
Risk Technical Support Center for OSRTI. Other EPA programs or external parties who may
choose of their own initiative to use these PPRTVs are advised that Superfund resources will not
generally be used to respond to challenges of PPRTVs used in a context outside of the Superfund
Program.
Questions Regarding PPRTVs
Questions regarding the contents of the PPRTVs and their appropriate use (e.g., on
chemicals not covered, or whether chemicals have pending IRIS toxicity values) may be directed
to the EPA Office of Research and Development's National Center for Environmental
Assessment, Superfund Health Risk Technical Support Center (513-569-7300), or OSRTI.
INTRODUCTION
In this update of the Provisional Peer Reviewed Toxicity Value, no p-RfD, p-RfC or
cancer assessment are provided because of a lack of sufficient data. Further, the provisional
subchronic RfD and the provisional chronic RfD described below are being retracted for the
following reasons:
•	The NTP (1992) conducted a 2-year gavage study with rats and identified the lowest
dose (15 mg/kg-day) as a Frank-Effect-Level (FEL) because of reduced survival at
that dose.
•	A NOAEL was not identified for the most sensitive species (rats), at any dose or
exposure duration, in a variety of studies.
2

-------
11-24-2004
• The LOAEL (30 mg/kg-day) used as the basis for the existing provisional subchronic
and chronic RfDs (IRDC, 1982a,b) was determined to be too close to the FEL and
inappropriate for deriving a Provisional Reference Dose.
The HEAST (U.S. EPA, 1997) lists subchronic and chronic oral RfD values of 2E-2 and
2E-3 mg/kg-day, respectively, for chloroacetic acid. The RfDs are based on a LOAEL (increased
incidences of myocarditis) of 21.4 mg/kg-day (30 mg/kg-day adjusted for a 5 day/week dosing
schedule) in rats administered chloroacetic acid for 90 days (IRDC, 1982a,b). Uncertainty
factors of 1000 (10 each for use of a LOAEL, rat to human extrapolation, and protection of
sensitive individuals) for the subchronic RfD and 10,000 (1000 as for the subchronic RfD and
another factor of 10 for use of a subchronic study) for the chronic RfD were applied to the
LOAEL to derive the critical values. The source document for the derivation was a Health and
Environmental Effects Document (HEED) for chloroacetic acid (U.S. EPA, 1988a). The HEAST
and source HEED do not include RfC derivations due to lack of data. Chloroacetic acid was
classified in Group D (not classifiable as to human carcinogenicity) in the HEED because the
evidence regarding the carcinogenicity of chloroacetic acid was inconclusive.
No RfD, RfC, or carcinogenicity assessment for chloroacetic acid is available on IRIS
(U.S. EPA, 2003a). The Drinking Water Standards and Health Advisories list (U.S. EPA,
2002b) does not report an RfD or MCL for chloroacetic acid, although an MCL of 0.06 mg/L is
reported for five haloacetic acids combined (including chloroacetic acid). No relevant
documents other than the previously mentioned HEED were located in the CARA list (U.S. EPA,
1991, 1994). ATSDR (2002) has not produced a Toxicological Profile for chloroacetic acid.
WHO (2002) does not have an Environmental Health Criteria Document for chloroacetic acid,
but does have a Poison Information Monograph for the chemical (WHO, 1998). The
carcinogenicity of chloroacetic acid has not been assessed by IARC (2002). The NTP (2002)
management status report was checked for recent studies. Exposure limits have not been
recommended by OSHA (2002) or NIOSH (2002), but ACGIH (2002) recommends a ceiling
TWA of 1 ppm for 15 minutes. Literature searches were conducted from 1987 thru 2002 for
studies relevant to the derivation of provisional toxicity values for chloroacetic acid. Databases
searched included: TOXLINE, MEDLINE, CANCERLIT, TSCATS, RTECS, CCRIS, DART,
EMIC/ EMICBACK, HSDB, and GENETOX. Another search of the literature was conducted in
May of 2004. No studies relevant to this document were located.
REVIEW OF PERTINENT DATA
Human Studies
A 5-year-old girl died from consumption of 5-6 mL of an 80% chloroacetic acid solution
(Feldhaus et al., 1993; Rogers, 1995). The girl developed signs of toxicity at approximately 1.5
3

-------
11-24-2004
hours post-ingestion that included refractory ventricular tachycardia, pulmonary edema, and
acidemia, and she died 8 hours after ingestion. Autopsy revealed diffuse gastric erosion, fatty
liver, and pulmonary and cerebral edema. Post mortem serum chloroacetic acid level was 100
mg/L. Chloroacetic acid and its sodium salt also cause eye and mucous membrane corrosion,
and death has resulted from dermal exposure to approximately 6-10% body surface (WHO,
1998). Reported clinical symptoms resulting from dermal exposure include vomiting, diarrhea,
CNS stimulation followed by CNS depression, coma, myocardial depression, shock, renal
failure, metabolic acidosis, and damage to the skeletal muscle, heart, and brain. Dose-response
data in humans are not available (Kulling et al., 1992).
Animal Studies
The subchronic and chronic toxicity of chloroacetic acid in rats and mice was studied by
the National Toxicology Program (NTP, 1992; Bryant et al., 1992; IRDC, 1982a,b). In the
subchronic study, which was designed to provide data for selecting dose levels for the chronic
bioassay, F344 rats and B6C3Fj mice (10/sex/dose) were administered chloroacetic acid (99%
pure) by gavage in deionized water 5 days/week for 13 weeks. Satellite groups of 5 rats and 5
mice per sex and dose were sacrificed after 4 and 8 weeks of treatment (a total of 20 rats and
mice per sex and dose were used in the studies). Rats and mice were administered chloroacetic
acid in deionized water at 0, 30, 60, 90, 120, or 150 mg/kg-day, and 0, 25, 50, 100, 150, or 200
mg/kg-day, respectively. The following parameters were evaluated: clinical signs of toxicity
(twice daily), mortality, body weight, organ weight (brain, heart, kidney, liver, lung, right testis,
and thymus [rats and mice], adrenal gland [rats only], and gall bladder [mice only]), gross
pathology, clinical chemistry (sodium, potassium, calcium, chloride [rats], phosphorus [rats],
blood urea nitrogen [BUN], creatinine [rats], total bilirubin [rats], aspartate aminotransferase
[AST], alanine aminotransferase [ALT], lactate dehydrogenase, total protein, albumin, albumin-
globulin ratio, cholinesterase, ornithine carbamyl transferase [rats], sorbitol dehydrogenase,
triiodothyronine, and thyroxin [T4] at Weeks 4, 8, and 13), hematology (erythrocyte count,
leukocyte count [and differential], hematocrit, hemoglobin, mean cell hemoglobin, mean cell
hemoglobin concentration, mean cell volume, and methemoglobin at Weeks 4, 8, and 13),
urinalysis (color, appearance, specific gravity, pH, protein, glucose, occult blood, nitrites,
urobilinogen, ketones, and bilirubin), and histopathology examination of 36 tissues in all animals
that died early, in rats dosed at 0, 30 (heart, lung with bronchi, and liver only), 60, 90, 120, or
150 mg/kg-day, and mice dosed at 0 or 200 mg/kg.
In rats, mortality rates at 0, 30, 60, 90, 120, and 150 mg/kg-day were 0/10, 0/10, 2/10,
9/10, 13/13, and 15/15 in males and 0/10, 1/10, 1/10, 10/10, 15/15, and 17/17 in females,
respectively (NTP, 1992). Only deaths at >90 mg/kg-day were considered related to treatment
(IRDC, 1982a). Clinical signs of toxicity included unspecified incidences of rattled breathing or
respiratory congestion in all treated groups (IRDC, 1982a). There were no biologically
significant changes in mean body weight throughout the study. Hematology and clinical
4

-------
11-24-2004
chemistry evaluations were performed at 4, 8 and 13 weeks. Clinical pathology data, however,
were not evaluated at 150 mg/kg-day in males or at 120 or 150 mg/kg-day in females at the 8-
week evaluations or at 90, 120, or 150 mg/kg-day in males or females at the 13-week evaluations
due to excessive mortality. All dose groups were evaluated at the 4-week evaluations. Changes
in hematology parameters consistent with dehydration (increased hematocrit values, hemoglobin
concentrations, and erythrocyte counts) were observed in males at 150 mg/kg-day (4-week
evaluation) (NTP, 1992). Similarly, increased red blood cell counts in females dosed at 90
mg/kg-day (8-week evaluation) were also attributed to mild dehydration. Water consumption
values were not reported. Significant increases in segmented neutrophils observed in males at
>90 mg/kg-day (4-week evaluation) and significant decreases in lymphocyte counts at >30
mg/kg-day (8-week evaluation) were attributed to stress.
A significant dose-related increase in BUN was observed in both males and females at 4
and 8 weeks. When compared with controls, BUN was significantly elevated in males at >90
mg/kg-day and in females at >60 mg/kg-day at the 4- and 8-week evaluations (NTP, 1992).
Increased BUN was considered a secondary effect caused by decreased renal perfusion from
cardiovascular failure, dehydration, or protein catabolism. Significant dose-related increases in
ALT activity were observed in males and females at 4 and 8 weeks. When compared with
controls, serum ALT activity was significantly elevated in males at 150 mg/kg-day (4-week
evaluation) and females at 60 (4- and 8-week), 120, and 150 mg/kg-day at the 4-week
evaluation. Significant dose-related trends in AST activity were observed at 4 and 8 weeks in
males and at 4 weeks in females. When compared with controls, serum AST levels were
significantly increased in males and females at 150 mg/kg-day (4-week evaluation). Elevated
AST activity was considered indicative of either hepatocellular or cardiac muscle damage.
Significant dose-related decreases in cholinesterase activity were observed at 8 and 13 weeks in
males and at 4, 8, and 13 weeks in females. When compared with controls, serum cholinesterase
activity in females was significantly decreased at >30 mg/kg-day (4- and 8-week evaluations) and
at 60 mg/kg-day after 13 weeks, and in males at >30 mg/kg-day at the 13-week evaluation. T4
was significantly greater than controls in males at >90 mg/kg-day at 4 and 8 weeks. The
researchers speculated that the effect on T4 may have been caused by a disruption in the
tricarboxylic acid cycle, causing caloric deprivation. Significant dose-related trends were
observed at 4 and 8 weeks in males and at 8 weeks in females. No effects were observed on
urinalysis indices.
Statistically significant alterations in absolute or relative organ weights occurred in
several dose groups; these included decreased relative heart weight in females at 30 and 60
mg/kg-day and males at 60 mg/kg-day, decreased absolute heart weight at 60 mg/kg-day in males
and females, and significantly decreased absolute adrenal weight at 60 mg/kg-day in males (NTP,
1992). Decreased absolute and relative heart weights observed in this study may indicate
treatment-related effects, because the heart has been shown to be a target organ for chloroacetic
acid. Relative liver and kidney weights were significantly greater than controls at 30 and 60
5

-------
11-24-2004
mg/kg-day in males, relative liver weights were significantly greater than controls at 60 mg/kg-
day in females, and absolute liver weights were significantly increased in males at 60 mg/kg-day.
These effects were considered to be related to chronic congestion (IRDC, 1982a). Gross
pathologic alterations in rats, which were considered secondary to myocarditis, included lung
congestion and presence of clear/red fluid or blood in the thoracic cavity in rats that died early
(IRDC, 1982a; NTP, 1992). Microscopic examinations revealed increased incidences of
cardiomyopathy in males and females at >60 mg/kg-day. The incidence at 0, 30, 60, 90, 120, or
150 mg/kg-day was 0/10, 0/10, 5/10, 9/9, 13/13, and 15/15, respectively, in males and 0/10, 0/10,
6/9, 10/10, 15/15, and 17/17, respectively, in females. The incidence at >60 mg/kg-day was
statistically significantly greater than control in both males and females. There appears to be a
discrepancy between the incidences reported in the IRDC report and the NTP report. IRDC
reported observing myocarditis in one low-dose male and female. Mild to severe multifocal or
diffuse acute passive congestion in the lungs was observed in rats that died early, but not in rats
that survived until terminal sacrifice. The lung congestion was considered to be secondary to
myocardial failure.
Overall, the study appeared sufficient to evaluate the subchronic toxicity of chloroacetic
acid in rats, although microscopic evaluations of most tissues were not conducted on low-dose
rats (NTP, 1992). The results suggest that the heart and liver, and possibly the kidneys are target
organs. The heart was the most obvious target for chloroacetic acid. The incidence of
cardiomyopathy was significantly increased at >60 mg/kg-day in both males and females.
Increased serum AST at high doses is also consistent with cardiac toxicity. Decreases in heart
weight were probably treatment-related and were the most sensitive measure of cardiac toxicity,
occurring even at the low dose of 30 mg/kg-day. Liver lesions were not observed, but
hepatotoxicity is suggested by serum chemistry changes (increased ALT and T4, decreased
cholinesterase) and increased liver weight. The most sensitive of these effects were seen at the
low dose of 30 mg/kg-day. Renal effects are suggested by increased kidney weight (as low as 30
mg/kg-day) and increased BUN, which occurred only at higher doses and may have been
secondary to cardiac toxicity. The low dose of 30 mg/kg-day was, therefore, a LOAEL in this
study for effects on the heart, liver and kidney. A NOAEL was not established.
An additional pilot study also was conducted that evaluated effects of chloroacetic acid
treatment on mitochondrial aconitase activity in female rats (3 rats/dose) administered a single
dose of chloroacetic acid at 24, 48, or 96 mg/kg-day (NTP, 1992). Heart (but not liver)
mitochondrial aconitase activity was inhibited in the pilot study at >24 mg/kg-day. These data
provide a potential mechanism of heart-induced toxicity of chloroacetic acid. It is not clear if
aconitase activity provides a sensitive endpoint for chloroacetic acid toxicity, because the doses
evaluated for the pilot study are not substantially different than those studied in the main study.
In mice, treatment-related mortality occurred at 200 mg/kg-day in both sexes (NTP,
1992). Mortality at study termination at 0, 25, 50, 100, 150, and 200 mg/kg-day was 2/10, 0/10,
6

-------
11-24-2004
0/10, 0/10, 0/10, and 10/10 in males, and 0/10, 0/10, 0/10, 1/10, 0/10, and 2/10 in females,
respectively. Most of the deaths occurred before the fourth week; the death of the female mouse
at 100 mg/kg-day was attributed to gavage injury. Body weights of female mice dosed at 200
mg/kg-day were 10% lower than controls after 13 weeks of treatment; the difference was
statistically significant (p<0.05). A significant dose-related decrease in cholinesterase activity
was observed at 8 and 13 weeks in females. Mean values at >150 mg/kg-day were significantly
less than controls. There were no other compound-related effects on other mean clinical
chemistry indices or on any hematology or urinalysis indices evaluated. Absolute and relative
liver weights were significantly greater than controls in females at 200 mg/kg-day. No effects on
macroscopic appearance of tissues were observed. No treatment-related microscopic lesions
were observed that were considered to be a direct toxicological effect. The cardiac lesions
observed in rats were not observed in mice. Overall, the study appeared sufficient to evaluate the
subchronic toxicity of chloroacetic acid in mice, although microscopic evaluations were only
performed on control and high-dose survivors and all mice that died early. The results suggest
that the liver is a target organ in mice, based on the observed decrease in serum cholinesterase
and increase in liver weight. The LOAEL was 150 mg/kg-day for decreased cholinesterase
activity in females. The NOAEL was 100 mg/kg-day.
Studies also were conducted by NTP as described above, except that chloroacetic acid
was administered in corn oil. Results of these studies were not included in the Technical Report
published by NTP (NTP, 1992); those data were obtained from IRDC (1982a,b). The results of
those studies were similar to the water vehicle studies in both rats and mice. In rats, treatment-
related increased mortality was observed at >90 mg/kg-day (IRDC, 1982a). Mortality rates were
0/10, 1/10, 1/10, 8/10, 10/10, and 10/10 in males and 0/10, 0/10, 1/10, 8/10, 10/10, and 10/10 in
females, respectively. There were no clinical signs of toxicity, and no biologically significant
changes in mean body weight throughout the study. IRDC reported that all significant changes in
hematology and clinical chemistry indices observed were random and not treatment-related.
Statistically significantly increased adrenal weights in males and females at 30, 60, and 90
mg/kg-day were observed. The toxicological significance of the adrenal weight changes is not
clear. Increased incidences of microscopic lesions of the adrenals were not observed; however,
in the absence of an effect on body weight, the effect on adrenal weight may indicate toxicity.
Gross pathologic alterations, which were considered secondary to myocarditis, included lung
congestion and presence of clear/red fluid or blood in the thoracic cavity in rats that died early.
Microscopic examinations revealed increased incidences of cardiomyopathy in males and
females at >30 mg/kg-day. Mild to severe multifocal or diffuse acute passive congestion in the
lungs was observed in rats that died early, but not in rats that survived until terminal sacrifice.
The lung congestion was considered to be secondary to myocardial failure. This study
established a LOAEL of 30 mg/kg-day for cardiac toxicity in rats. A NOAEL was not identified.
In mice, mortality rates were similar to those observed when chloroacetic acid was
administered in water (IRDC, 1982b). Mortality rates were 0/10, 0/10, 0/10, 0/10, 3/10, and
7

-------
11-24-2004
10/10 in males and 0/10, 0/10, 0/10, 1/10, 0/10, and 7/10 in females, respectively. Most of the
deaths occurred before the fourth week; the death of the female mouse at 100 mg/kg-day was
attributed to gavage injury. Infrequent signs of toxicity, including piloerection, body tremors,
hypoactivity, ataxia, hypothermia, bradycardia, low carriage, prostration, and hypopnea were
observed at 200 mg/kg-day. No effects on body weight were observed. There did not appear to
be any treatment-related effects on hematology, clinical chemistry, or urinalysis indices. All
statistically significant organ weight changes were considered to be within the range of normal
biological variability. No effects on macroscopic appearance of tissues were observed, and there
were no treatment-related microscopic lesions that were considered to be a direct toxicological
effect. The study did not identify any target organs in mice. The 150 mg/kg-day dose was a FEL
for treatment-related mortality. No effects were observed at 100 mg/kg-day or lower.
Another oral subchronic study was conducted by Daniel et al. (1991). Male and female
Sprague-Dawley rats (10/sex/dose) were administered daily doses (7 days/week) of chloroacetic
acid sodium salt in distilled water via oral gavage at 15, 30, 60, or 120 mg/kg-day at a dosing
volume of 2 mL/kg for 90 days. The doses correspond to approximately 12, 24, 48, and 96
mg/kg-day of chloroacetic acid. The following parameters were evaluated for treatment-related
effects: clinical signs of toxicity, body weights (twice weekly and at study initiation and
termination), water and food consumption (three times per week), hematology (red and white
blood cell counts, hemoglobin, hematocrit, reticulocyte counts, mean corpuscular volume, and
differential leukocyte count), clinical chemistry (BUN, serum calcium and phosphorous,
creatinine, total cholesterol, glucose, lactate dehydrogenase, ALT, and AST), complete gross
necropsy, organ weights (brain, liver, spleen, lung with lower half of trachea, thymus, kidneys,
adrenal gland, heart, and gonads), and microscopic examination of 38 tissues and all gross
lesions. Only tissues from control and high-dose animals were microscopically examined, except
that target organs (identified in high-dose animals) in animals of all dose groups were
microscopically examined (due to high mortality at 120 mg/kg-day, however, 60 mg/kg-day was
the highest male dose group evaluated for microscopic pathology). Tissues from 5 control
animals per sex (and all surviving high-dose animals) were also subjected to microscopic
evaluations.
At 120 mg/kg-day, 8/10 males and 3/10 females died (Daniel et al., 1991). Also, one
male each at 15 and 60 mg/kg-day died. Increased early mortality at 120 mg/kg-day was
attributed to chemical-induced toxicity. It also appears that mortality at 15 (1/10) and 60 (1/10)
mg/kg-day was attributed to chloroacetic acid treatment because the study authors used early
mortality at 15 mg/kg-day as supporting evidence of a LOAEL at that dose. No effects on
clinical signs of toxicity or body weight were reported. Water consumption at 120 mg/kg-day
was greater than controls in males and females, and food consumption was lower than controls in
males at 120 mg/kg-day. Statistical analyses were not performed on those data, however,
because of low survival. At lower doses, no statistically significant effects on food or water
consumption were observed. Hematology analyses indicated that white blood cell counts at >30
8

-------
11-24-2004
mg/kg-day and segmented neutrophils at > 60 mg/kg-day were significantly increased (statistical
significance was not determined for high-dose males due to decreased survival). Also, monocyte
counts were significantly increased in males at 15, 30, and 60 mg/kg-day and were significantly
decreased at 15 mg/kg-day in females. Clinical chemistry results suggest effects on the liver and
kidney. Indications of liver effects included significantly increased ALT activity at 15 and 30
mg/kg-day in males (ALT was also elevated at 120 mg/kg-day in males, but the data were not
statistically evaluated) and at 120 mg/kg-day in females. AST activity in high-dose females also
was statistically greater than controls (AST also was elevated at 120 mg/kg-day in males, but the
data were not statistically evaluated). Increased AST activity also could represent toxicity to the
heart. Evidence of kidney toxicity included statistically significant increases in BUN levels at 15
and 30 mg/kg-day in males and at 120 mg/kg-day in females, increased creatinine levels at > 15
mg/kg-day in males and at 30 and 60 mg/kg-day in females, increased phosphate levels at 120
mg/kg-day in females, and increased calcium levels in males at 15 and 30 mg/kg-day.
Gross pathology examinations revealed increased incidences of pale-yellow livers at > 15
mg/kg-day in males and at 60 and 120 mg/kg-day in females (Daniel et al., 1991). Reddened
lungs also were observed in male and female animals that died early (Days 1-3) at 120 mg/kg-
day. A statistically significant (P=0.035) trend in the incidence of heart inflammation was
observed (pooled male and female data), although the incidence did not achieve statistical
significance at any dose group in pair-wise comparison with controls. The incidence at 0, 15, 30,
60, and 120 mg/kg-day was 1/10, 1/10, 3/10, 3/10, and 4/7, respectively, in males and 4/10, 5/9,
6/10, 7/9, and 2/2, respectively, in females. A significant (P<0.001) dose-related increase in the
incidence of chronic nephropathy in the 90-day study also was observed in males that achieved
statistical significance at > 60 mg/kg-day (high-dose males were excluded from analysis due to
high early mortality). The incidence at 0, 15, 30, and 60 mg/kg-day was 3/10, 4/9, 5/10, and 9/9,
respectively. A significant dose-related trend (P=0.013) also was observed in the incidence of
hepatocytic vacuolated foci in males, although the incidence was not significant at any dose in
pair-wise comparison with controls. The incidence at 0, 15, 30, and 60 mg/kg-day was 0/10,
0/10, 1/10, and 3/9. A significant dose-related trend (P0.001) also was observed in the
incidence of splenic pigments in males that achieved statistical significance at 60 mg/kg-day
when compared with controls. Incidence of this lesion at 0, 15, 30, and 60 mg/kg-day was 2/10,
1/9, 6/10, and 9/9, respectively. Congestion and hemorrhage of the lungs was observed in treated
animals that died early (particularly at the two highest male and the highest female dose groups),
but was not observed in surviving animals.
Overall, there were no serious deficiencies in the study design or conduct that are
expected to substantially affect the sensitivity of the study but a high incidence of heart
inflammation (4/10) in untreated females and chronic nephropathy (3/10), in untreated males,
limits the confidence which can be placed in the results. Although the hematology and clinical
chemistry evaluations were somewhat limited and urinalysis and ophthalmic examinations were
not conducted, an independent 90-day gavage study [NTP, 1992] did not report treatment-related
9

-------
11-24-2004
effects on urinalysis or ophthalmic parameters. In the Daniel et al. (1991) study, a LOAEL of 15
mg/kg-day of chloroacetic acid sodium salt (approximately 12 mg/kg-day of chloroacetic acid)
was achieved based on the observation of one early death, discolored livers in males, changes in
serum enzymes (BUN, ALT, serum calcium, and creatinine), and significant dose-related trends
in incidences of microscopic lesions (cardiac inflammation, chronic nephropathy, hepatocytic
vacuolated foci, splenic pigmentation) in males (although statistical significance was not
achieved at the low dose for any lesion). A NOAEL was not achieved.
In a subchronic drinking water study (Bhat et al., 1991), five male Sprague-Dawley rats
were exposed to chloroacetic acid (>99% pure) at a concentration (1.9 mM) intended to provide a
daily dose of 19 mg/kg-day (1/4 the LD50) for 90 days (other chloroacetic acids also were
evaluated; those results are not reported in this evaluation). The following parameters were
evaluated: body weights, organ weights (unspecified organs, but included the liver and testes),
gross pathology (unspecified details), and microscopic pathology on selected tissues (including
liver, lung, heart, spleen, thymus, kidneys, testes, pancreas, and brain). Mortality data were not
reported, and there were no effects on body weight. A statistically significant (10%) decrease in
absolute, but not relative, liver weights compared with controls was observed. The biological
significance of the liver weight changes is not clear because results of subchronic gavage studies
revealed treatment-related increases in liver weights and because relative liver weights were not
affected by treatment. No gross lesions were reported. Microscopic examinations revealed
minimal to mild collagen deposition, portal vein dilation/extention, fibrosis, edema, and
occasional foci of inflammation in the liver (incidence not reported). These observations were
generally not observed in controls (except that one control rat was observed with mild collagen
deposition). Perivascular inflammation of the lungs also was observed. This lesion was
"extremely rare" in controls; incidences were not reported. The study design was limited by the
use of only one dose group that contained only 5 males, the lack of clinical chemistry and
hematology evaluations, limited histopathology examinations, and lack of dose confirmation. A
LOAEL of approximately 19 mg/kg-day was achieved for this study (the only dose evaluated).
A summary of the subchronic effect levels is presented in Table 1. A NOAEL has not
been established in rats in any of the available studies. Target organs identified by the
subchronic studies include the heart, liver, kidneys, and lungs. The lowest LOAEL observed was
15 mg/kg-day for chloroacetic acid sodium salt, which corresponds to approximately
12 mg/kg-day of chloroacetic acid.
In a 2-year bioassay conducted by the National Toxicology Program (NTP, 1992), 53
F344/N rats and 60 B6C3Fj mice per sex and dose were administered chloroacetic acid in
deionized water via oral gavage 5 days/week for 2 years at 15 or 30 mg/kg-day (rats) or 50 or 100
mg/kg-day (mice). The following toxicological parameters were evaluated in animals treated for
2 years: body weights (recorded once pretest, weekly for 13 weeks, monthly between Week 13
and 21 months, and biweekly thereafter), mortality, clinical signs of toxicity (animals were
10

-------
11-24-2004
observed twice daily for morbidity and mortality, and detailed observations of clinical signs were
conducted every 4 weeks), gross pathology, and microscopic pathology of 33 tissues (in addition
to all gross lesions and associated lymph nodes). An additional 10 rats per sex and dose were
sacrificed after 6 months of treatment (NTP, 1992). A complete necropsy was conducted on
those animals, the brain, heart, and right kidney were weighed, and sections of the heart were
microscopically examined (the heart was identified as a target organ in the 13-week range-
finding study). No other toxicological parameters were evaluated on 6-month interim sacrifice
animals. Also, an additional 7 rats per sex and dose were sacrificed after 15 months of treatment.
A complete necropsy was conducted on those animals, the brain, heart, right kidney, and liver
were weighed, and a microscopic examination of 33 tissues (and all gross lesions with associated
lymph nodes) was performed in control and high-dose animals (gross lesions also were
microscopically examined at lower doses). In addition, clinical chemistry (alkaline phosphatase,
alanine aminotransferase, lactate dehydrogenase, creatine phosphokinase, hydroxybutyrate
dehydrogenase, total protein, and albumin) and hematology (leukocyte count [absolute and
differential], erythrocyte count, hemoglobin, hematocrit, mean cell volume, mean cell
hemoglobin, and mean cell hemoglobin concentration) parameters were evaluated.
In rats, survival rates at control, low-, and high-dose groups were 53%, 40%, and 32%,
respectively, in males and 70%), 38%), and 51 %>, respectively, in females (NTP, 1992). Increased
mortality followed a statistically significant trend in treated males (P=0.011) and females
(P=0.043). Pairwise comparisons revealed significantly increased mortality in the high-dose
male group (P=0.015) and low- (P=0.001) and high-dose (P=0.046) female groups compared
with controls. Increased mortality at all dose groups was attributed by the researchers to
chemical toxicity. NTP concluded that survival was adequate for detection of chemical-related
neoplasms because over 50% of the animals in all dose groups survived until at least Week 93.
Also, appropriate survival-adjusted analyses were used to statistically evaluate tumor incidences.
No treatment-related clinical signs of toxicity were observed. The average mean body weight of
high-dose males was 5% less than controls for the second year of the study. Final mean body
weights of low- and high-dose animals were 5% and 8% less than controls, respectively, in males
and were 2% and 3% less than controls, respectively, in females. Statistical significance was not
indicated. No treatment-related changes in clinical chemistry or hematology parameters were
observed. Statistically significant changes in absolute and relative organ weights were observed
at the 6-month interim sacrifice (NTP, 1992). Relative kidney weights of low- and high-dose
females and absolute kidney weights of high-dose females were significantly less than controls,
and relative kidney weights of high-dose males were significantly greater than controls. Absolute
brain weights of low- and high-dose females were significantly less than controls, and relative
brain weights of low-dose animals were significantly less than controls. Relative heart weights
of high-dose females were significantly greater than controls. No effects on organ weights were
observed at the 15-month sacrifice; therefore, it is not clear whether effects seen at 6 months are
11

-------
11-24-2004
Table 1. A Summary of the Effect Levels from the Available Oral Subchronic Studies
Study
Citation
Exposure
Route
Species
Tested
Dose Range
(mg/kg-day)
LOAEL
(mg/kg-
day)
NOAEL
(mg/kg-
day)
Basis for LOAEL
NTP,
1992;
IRDC,
1982a,b
Oral,
gavage in
water
Rats
30 - 150
30
None
Decreased cholinesterase
activity, increased liver and
kidney weight, decreased
heart weight
Mice
25 - 200
150
100
Decreased cholinesterase
activity
IRDC,
1982a,b
Oral,
gavage m
corn oil
Rats
30 - 150
30
None
Cardiomyopathy
Mice
25 - 200
150
100
Mortality
Daniel et
al„ 1991
Oral,
gavage in
water
Rats
15-120 (salt)
12-96 (CA)
15 (salt)
12 (CA)
None
Discolored livers, increased
serum enzymes (ALT,
BUN, creatinine), possible
early mortality
Bhat et
al, 1991
Oral,
drinking
water
Rats
19
19
None
Microscopic lesions in liver
and lung
CA = chloroacetic acid
indicative of chloroacetic acid-induced toxicity. These results also are not consistent with organ
weight changes observed in the subchronic study, which observed decreases in absolute and
relative heart weights and increases in relative kidney weights.
No treatment-related gross lesions were reported (NTP, 1992). A statistically significant
positive trend in incidences of uterine endometrial stromal polyps was observed in females that
achieved statistical significance at both dose groups compared with controls (incidence in the
control, low, and high-dose group was 1/53, 7/53, and 9/53). NTP concluded that the increased
incidences of stromal polyps were not likely treatment-related because the control incidence was
unusually low and the incidences in the dose groups were within historical control values (range
of 10% to 38%). Small decreases in several common neoplasms (e.g., adrenal medulla,
neoplasms of the thyroid C-cells, and mononuclear cell leukemia in males and adenoma of the
pituitary pars distalis in males and females) were observed. NTP considered these decreases to
be related to decreased survival. Microscopic lesions of the heart had been observed in the
subchronic range-finding study in rats, but were not observed in the 2-year bioassay. The lack of
12

-------
11-24-2004
effects on the heart may have been caused by the lower doses employed in the long-term study.
Although target organ effects were not found, the low dose of 15 mg/kg-day is a FEL for reduced
survival in the female rats. The decrease in survival indicates that the maximum tolerated dose
(MTD) was achieved, but also may have limited the sensitivity of the study to detect tumor
development. Although NTP concluded that survival was adequate for detection of chemical-
related neoplasms (because at least 50% of animals in each group survived to week 93), NTP
also conceded that small decreases in incidences of several tumor types in treated animals were
probably secondary to reduced survival. The study found no evidence of tumor production by
chloroacetic acid in rats.
In mice, a significant (P<0.001) positive dose-related trend in mortality was observed in
males (NTP, 1992). Survival rates for the control, low-, and high-dose males were 79%, 65%,
and 38%, respectively. The decrease in the high-dose group was statistically significant and
appeared to be due, at least in part, to chemical-related toxicity. NTP concluded that survival
was adequate for detection of chemical-related neoplasms because over 50% of male mice
survived until Week 85, even though only 38% of high-dose male mice survived to study
termination. Survival of female mice was similar to controls. Appropriate survival-adjusted
analyses were used to statistically evaluate tumor incidences. No treatment-related clinical signs
of toxicity were observed. Body weights of female mice were consistently 8% to 11% less than
controls throughout the second year of the study. Final mean body weights of low- and high-
dose animals were 2% and 0% less than controls, respectively, in males and were 2% and 6%
less than controls, respectively, in females. Statistical significance was not indicated. NTP
concluded that the consistent decrease in body weight of high-dose females represented a
treatment-related toxic effect. No treatment-related effects on clinical chemistry or hematology
were observed. No treatment-related gross lesions were reported (NTP, 1992). Microscopic
pathology revealed a significant increase in the incidence of squamous cell hyperplasia of the
forestomach in high-dose males and females that was attributed to the irritant properties of
chloroacetic acid. The incidence of this lesion in control, low-, and high-dose groups,
respectively, was 5/60, 2/60, and 13/60 in males and 5/60, 8/59, and 15/60 in females. Squamous
cell papillomas of the forestomach occurred in two high-dose females (no control or low-dose
females were observed with this lesion); however, NTP concluded that the incidence was within
historical-control range reported for this type of lesion. Acute nasal inflammation was
significantly greater than controls in high-dose males and low- and high-dose females. The
incidence of this lesion in control, low-, and high-dose groups, respectively, was 3/60, 7/59, and
24/60 in males and 5/60, 15/60, and 31/60 in females. Increased incidences of metaplasia of the
olfactory epithelium also was significantly increased in high-dose females. The incidence of this
lesion in control, low-, and high-dose female groups, respectively, was 2/60, 5/60, and 17/60.
NTP concluded that the nasal lesions may have resulted from reflux of the gavage solution rather
than systemic chloroacetic acid toxicity (NTP, 1992). However, because nasal inflammation was
also observed in a 2-year drinking water-exposure study, the nasal lesions observed in this study
may be relevant to human exposure (DeAngelo et al., 1997).
13

-------
11-24-2004
No increases in tumor incidences were found (NTP, 1992). A significant dose-related
decreasing trend in the incidence of malignant lymphomas was observed in female mice that
achieved statistical significance at the high-dose group (incidence of 29/60, 18/60, and 13/60 in
the control, low-, and high-dose groups, respectively). A reason for the decrease is not clear. A
LOAEL of 50 mg/kg-day in mice (the lowest dose evaluated) appeared to be established for this
study based on increased incidences of microscopic lesions of the nasal mucosa in low-dose
females. Effects at the higher dose included metaplasia of the olfactory epithelium in females,
squamous cell hyperplasia of the forestomach in males and females, reduced body weight in
females, and reduced survival in males. Therefore, the maximum tolerated dose appears to have
been achieved in mice. Increased early mortality of high-dose male mice could have limited the
sensitivity of the study to detect tumor development, but NTP considered survival in all groups to
be adequate because 50% or more survived to week 85. The study found no evidence of tumor
production by chloroacetic acid in mice.
In a drinking water study, groups of 50 male F344/N rats were exposed to chloroacetic
acid (>99% pure) in drinking water at concentrations of 0.05, 0.5, or 2 g/L (the high
concentration was lowered to 1.5 g/L at 8 weeks and 1 g/L at 24 weeks due to excessive toxicity
[substantially decreased body weight gains]) for up to 104 weeks (DeAngelo et al., 1997).
Between 18 and 21 rats from each group were removed for interim sacrifice at 15, 30, 45, or 60
weeks (unspecified number of animals per sacrifice period). Time-weighted average doses
calculated by the researchers were 3.5, 26.1, or 59.9 mg/kg-day. The following parameters were
evaluated: mortality, body weights, water consumption, clinical signs of toxicity, clinical
pathology (serum AST, ALT, cyanide-insensitive palmitoyl coenzyme A oxidase activity, and
hepatocyte proliferation), organ weights (liver, kidneys, spleen, and testes), gross pathology
(comprehensive in all animals at terminal sacrifice, but limited to body, liver, kidneys, spleen,
urinary bladder, and testes in animals at interim sacrifices), and histopathology (comprehensive
in high-dose animals [and apparently controls, although that was not specified] at terminal
sacrifice, but limited to the liver, kidneys, spleen, and testes in lower dose animals at terminal
sacrifice and interim sacrifice animals at all dose groups).
Survival in treated groups was reported in the text not to be significantly different from
controls (DeAngelo et al., 1997). Table 1 of the report shows an apparent increase in
unscheduled deaths in the high-dose group (6, 7, 9, and 14 in the control, low-, mid- and high-
dose groups, respectively), but contains an error, as the numbers of animals killed at interim
sacrifice (21), dying early (14), and killed at terminal sacrifice (25) in the high-dose group add up
to 60, rather than group size of 50 listed in the table and reported in the methods section. Group
sizes reported for organ weight and histopathology results in Tables 2 and 3 of the report
correspond to the numbers given for terminal sacrifice in Table 1. Therefore, it appears that the
text is correct in stating that there was no effect of treatment on survival and that the number of
animals surviving to terminal sacrifice was 23-25 in all groups, including the high-dose group, as
reported in Table 1. Water consumption of mid- and high-dose animals was significantly less
14

-------
11-24-2004
than controls throughout the study. Final mean body weights of mid- and high-dose animals
were statistically and biologically significantly less than controls (final mean body weights of
mid- and high-dose animals were 13% and 38% lower than controls, respectively). No effects
were observed on the limited clinical pathology parameters evaluated. Analysis of organ weight
data is complicated by the substantially decreased body weights in the mid- and high-dose
groups. In these groups, absolute and relative liver weights were significantly less than controls,
relative testes weights were significantly greater than controls, and absolute kidney weights were
significantly less than controls. Also, absolute and relative spleen weights were significantly
increased at the low dose (absolute spleen weights at the mid- and high-doses were less than
controls, possibly due to decreased body weights). These effects may have been caused by
decreased body weights.
Increased incidences of myocardial degeneration and inflammation of the nasal cavities of
high-dose rats were observed at 104 weeks compared with controls (incidence not reported) that
exceeded historical-control values for Fischer rats (although values in the historical-control
database were not obtained from the testing laboratory) (DeAngelo et al., 1997). It did not
appear that the heart or nasal cavity was microscopically examined at lower doses. Increased
incidences of chronic liver inflammation were observed that were not considered treatment
related. Incidence data were not reported, and the study authors did not specify why the lesions
were not considered treatment related. No treatment-related increase in neoplasms was observed.
Although no effects were observed at the low dose, study design limitations (particularly the
absence of a microscopic examination of tissues other than liver, kidneys, spleen, and testes from
low- and mid-dose animals, regardless of the presence of lesions in the high-dose group)
preclude derivation of reliable chronic NOAEL or LOAEL values. The body weight data
indicate that the MTD was achieved at the mid dose and exceeded at the high dose. Sufficient
numbers of animals survived to terminal sacrifice in all groups for evaluation of tumor data. No
increase in tumor incidence was seen in any group.
An older study included groups of 18 B6C3Fj and 18 B6AKFj mice/sex that were
administered chloroacetic acid in distilled water by stomach tube daily at 46.4 mg/kg from days
7-28 of age (BRL, 1968). The mice were subsequently treated in the diet at a concentration of
149 ppm for 78 weeks. Dose selection was based on prechronic studies; the dose was not
adjusted to changing body weight during the 3 weeks of gavage treatment, but a single
adjustment was made at the time of conversion from stomach tube to incorporation in the feed.
Based on U.S. EPA (1988b) reference values, the daily dose during the feeding part of the study
was approximately 25.6 mg/kg-day. Four untreated groups and 1 gelatin treated group
containing 18 mice/strain/sex each served as controls. Following the treatment period, all
surviving mice were dissected and examined grossly, and tissue samples from the chest contents,
liver, spleen, kidneys, adrenals, stomach, intestines, and genitals were examined microscopically.
Mice that were sacrificed when moribund were subjected to gross pathologic examinations, but
histological examinations were performed only when deemed appropriate (criteria not specified).
15

-------
11-24-2004
At least 15 treated mice per strain survived to the end of the study. No statistically significant
(p<0.05) increases in tumor incidences were found when any group or combination of treated
groups was compared with individual or pooled control groups.
A summary of effect levels from the chronic oral studies is reported in Table 2. Effect
levels suitable for use in risk assessment cannot be derived based on the available studies. In the
study conducted by NTP, increased incidences of early mortality was observed at all dose levels
in the most sensitive species tested, thus precluding the use of chronic RfD derivation. The study
conducted by BRL was not adequate based on the limited histopathology evaluation and the lack
of clinical pathology examinations.
Ten sexually mature female Hsd:Sprague Dawley SD rats were exposed to chloroacetic
acid in the drinking water throughout pregnancy (Days 1 - 22 of pregnancy) at 1570 ppm (193
mg/kg-day) (Johnson et al., 1998). Controls (N=55) were given distilled water. On Day 22 of
gestation, all rats were sacrificed and examined for external and internal abnormalities, and the
gravid uterus was removed and opened. The number of implantation sites and resorption sites
were tabulated, and fetuses and placentas were examined in situ, removed, and individually
examined, and the ovaries were removed. The following parameters were evaluated: fetal
placements, weights, placental weights, crown rump lengths, and gross fetal abnormalities.
Congenital abnormalities were examined in abdominal organs, and the heart was examined in
situ, removed and microscopically examined for abnormalities (the great arterial and venous
connections also were inspected). There were no treatment-related effects on any parameter
evaluated, although the scope of parameters evaluated was somewhat limited compared with
standard guidelines for developmental toxicity studies.
Data on the developmental toxicity of chloroacetic acid were reported in a study abstract
(Smith et al., 1990). A full report does not appear to be available in the publically available
literature. Chloroacetic acid in distilled water was administered to pregnant Long-Evans rats on
gestation days 6-15 via oral gavage at 17, 35, 70, or 140 mg/kg-day. The following maternal
toxicity endpoints were evaluated: clinical signs of toxicity, body weight change, gross pathology
of unspecified tissues, and uterine contents at necropsy. Toxicity to live fetuses was determined
by external, skeletal, and soft-tissue malformations (additional details were not provided).
Maternal body weight gains were significantly less than controls at the high dose. The mean soft
tissue malformation frequency was elevated at 140 mg/kg-day compared with controls (incidence
was 6.37% at the high dose, but was not reported for lower doses); however, a clear, consistent
dose-related trend was not observed. Incidences of cardiovascular malformations were
significantly greater than controls at 140 mg/kg-day (including levocardia). The maternal and
developmental LOAEL was 140 mg/kg-day, and the maternal and developmental NOAEL was
70 mg/kg-day.
16

-------
11-24-2004
Table 2. A Summary of the Effect Levels from the Available Chronic Oral Studies
Study
Citation
Exposure
Route
Species
Tested
Doses
(mg/kg-
day)
LOAEL
(mg/kg-
day)
NOAEL
(mg/kg-
day)
Basis for LOAEL
Neoplasms
NTP, 1992
Oral,
gavage
Rats
15 or 30
15
None
Increased mortality
None
Mice
50 or 100
50
None
Microscopic lesions
of the nasal mucosa
None
DeAngelo
et al., 1997
Oral,
drinking
water
Rats
3.5, 26.1,
or 59.9
N/A
N/A
N/A
None
BRL, 1968
Oral,
gavage
and diet
Mice
46.4 from
age 7-28,
then 25.6
N/A
N/A
N/A
None
N/A = precluded by study design
An English summary of a Russian study (Maksimov and Dubinina, 1974) reported that
chronic inhalation of chloroacetic acid caused weight reduction, decreased oxygen uptake and
rectal temperature, hemoglobinemia and inflammatory changes in the respiratory organs of rats
and guinea pigs at > 5.8 mg/m3. Additional information regarding the design and results of this
study was not reported in the summary (U.S. EPA, 1988a).
Dermal chloroacetic acid exposure (2 mg, 3 times/week for life) to 50 female IcR/Ha
mice did not result in significant increases in tumor incidences (Van Duuren et al., 1974),
although study adequacy could not be evaluated based on lack of experimental design details.
Also, Van Duuren et al. (1974) reported observing sarcomas at the application site in 3 out of 50
IcR/Ha mice administered 0.5 mg s.c. injections of chloroacetic acid weekly for life, versus 0/50
in controls. Four of 18 treated B6C3F1 mice administered a single s.c. injection of chloroacetic
acid and monitored for 78 weeks were observed with hepatomas; however, control incidences
were not reported (BRL, 1968). Identically treated B6AKF1 mice did not develop hepatomas.
The increase was not statistically significant and was not clearly associated with chloroacetic acid
treatment.
Other Studies
Chloroacetic acid was not mutagenic in Salmonella typhimurium strains TA100, TA1535,
TA1537, or TA98, with or without exogenous metabolic activation, but was mutagenic in
17

-------
11-24-2004
cultured mammalian (L5178Y) cells in vitro (NTP, 1992). Chloroacetic acid induced sister
chromatid exchanges in Chinese hamster ovary cells and produced positive results in an in vivo
chromosome aberrations assay (NTP, 1992; Bhunya and Das, 1987). However, chloroacetic acid
did not produce chromosome aberrations in Chinese hamster ovary cells in vitro, with or without
metabolic activation (NTP, 1992). Chloroacetic acid was positive in an in vivo sperm
abnormality assay in mice (Bhunya and Das, 1987). Chloroacetic acid administered in feed was
negative for the induction of sex-linked recessive lethal mutations in germ cells of male
Drosophila melanogaster; however, equivocal results were obtained when the test substance was
administered by injection (NTP, 1992). These data suggest that chloroacetic acid has some
genotoxic potential.
DERIVATION OF PROVISIONAL SUBCHRONIC AND CHRONIC
ORAL RfD VALUES FOR CHLOROACETIC ACID
Critical effect levels from subchronic and chronic oral studies of chloroacetic acid are
shown in Tables 1 and 2, respectively. The subchronic studies identified the heart, liver, and
kidneys as targets of chloroacetic acid in laboratory animals (NTP, 1992; IRDC, 1982a,b; Daniel
et al., 1991; Bhat et al., 1991). These organs are also among the targets that have been identified
in humans following acute exposure to high doses of chloroacetic acid (Feldhaus et al., 1993;
Rogers, 1995; Kulling et al., 1992). No human data are available for repeated exposure to lower
doses of the chemical. In the animal studies, rats were considerably more sensitive to
chloroacetic acid than mice. Gavage studies in mice (corn oil or water vehicle) found no effects
at doses up to 100 mg/kg-day, with the first indication of toxicity being decreased serum
cholinesterase activity at 150 mg/kg-day when tested with water vehicle (NTP, 1992) or
increased mortality at 150 mg/kg-day when tested with corn oil vehicle (IRDC, 1982b). NOAEL
values were not identified in any of the rat studies. The lowest dose tested produced effects in
each of the studies (cardiomyopathy at 30 mg/kg-day in the corn oil gavage study [IRDC, 1982a],
decreased serum cholinesterase activity and heart weight and increased liver and kidney weights
at 30 mg/kg-day in the water gavage study by NTP [1992], liver pathology and serum enzyme
markers of liver and kidney toxicity at 12 mg/kg-day in the water gavage study by Daniel et al.
[1991], and liver and lung histopathology at 19 mg/kg-day in the drinking water study [Bhat et
al., 1991]). The lowest LOAEL was 12 mg/kg-day in the study by Daniel et al. (1991).
Developmental toxicity was studied in two strains of rat. No fetal effects were observed in
a limited study of Sprague-Dawley rats at 193 mg/kg-day (Johnson et al., 1998). The other study,
available only as an abstract (Smith et al., 1990), reported an increased incidence of
cardiovascular malformations, but only at a high dose that also produced maternal toxicity (140
mg/kg-day, with a NOAEL of 70 mg/kg-day). These results suggest that the developing fetus is
not a sensitive target for chloroacetic acid. Studies of reproductive toxicity were not located in
the available literature.
18

-------
11-24-2004
The data do not support derivation of a provisional subchronic RfD for chloroacetic acid.
Confidence in the overall database is low-to-medium because, although several subchronic
studies on chloroacetic acid are available, there are no available reproductive toxicity studies, and
developmental studies, available for only one species, were limited by deficiencies in study
design or reporting. Although the LOAEL of 12 mg/kg-day in the Daniel et al. (1991) study is the
most sensitive effect level identified, the high incidence of heart inflammation (4/10) in untreated
females and chronic nephropathy (3/10) in untreated male control rats limits the confidence
which can be placed in the results. Furthermore, the unexplained death of a male rat at the
LOAEL suggests that 12 mg/kg-day could be considered to be an adverse effect. That concern is
supported by the NTP (1992) 2-year study with rats which reported reduced survival at an
exposure level of 15 mg/kg-day. The subchronic LOAEL (30 mg/kg-day) identified in the NTP
(1992) study was considered too close to the chronic FEL of 15 mg/kg-day which cause reduced
survival in male rats. Because none of the subchronic studies cited here has identified a NOAEL
or an unequivocal LOAEL that was not associated with mortality, an RfD for subchronic
exposure cannot be derived for chloroacetic acid.
The data do not support derivation of a provisional chronic RfD for chloroacetic acid.
The lowest dose tested in the NTP (1992) study, 15 mg/kg-day, was a FEL that produced
decreased survival in treated rats. DeAngelo et al. (1997) included a lower dose level in their
study, and found no effect on survival, but the study could not be used to derive a NOAEL or
LOAEL because there was no histopathological examination of the heart and nasal cavity in the
two lower dose groups, even though both of these tissues were identified as targets in the
histopathological examination of the high-dose group. Nasal lesions were the most sensitive
target in mice in the NTP (1992) study and occurred at the lowest dose tested (50 mg/kg-day),
but the doses used in this species were considerably higher than in rats. The only other chronic
study available (BRL, 1968) was conducted at a high dose and did not provide any information
regarding nonneoplastic endpoints. The subchronic data in the NTP (1992) study could not be
used to derive a chronic RfD due to the proximity of the subchronic LOAEL (30 mg/kg-day) to
the chronic FEL (15 mg/kg-day; 10.7 mg/kg-day adjusted for intermittent dosing).
DERIVATION OF PROVISIONAL SUBCHRONIC AND CHRONIC
INHALATION RfC VALUES FOR CHLOROACETIC ACID
No adequate human or animal data are available regarding the toxicity of chloroacetic
acid following subchronic or chronic inhalation exposure, precluding derivation of p-RfC values
for this substance.
19

-------
11-24-2004
DERIVATION OF A PROVISIONAL CARCINOGENICITY ASSESSMENT
FOR CHLOROACETIC ACID
There are no data on the carcinogenicity of chloroacetic acid in humans. Cancer
bioassays in rats and mice exposed via gavage or drinking water have provided no evidence that
chloroacetic acid produces tumors (NTP, 1992; DeAngelo et al., 1997; BRL, 1968). There is
some question as to interpretation of these studies, however. Increased early mortality of high-
dose male rats, low- and high-dose female rats, and high-dose male mice in the NTP study
appears to have limited the sensitivity of the study to detect tumor development, which is
supported by the observation of marginal decreases in incidences of several tumor types in
treated animals. Furthermore, the study by DeAngelo et al. (1997) was not adequately designed
to characterize the carcinogenicity of chloroacetic acid because all tissues from animals at the
low- and mid-dose groups were not subjected to a microscopic examination even when lesions
were observed at higher doses. Because tumor development may have been affected by the
severe decreases in body weight (38%) at the high dose compared with controls, microscopic
evaluation at lower doses (where the decrease in body weight was less severe) may have
provided useful data regarding the tumorigenic capability of chloroacetic acid. The study by
BRL (1968) included small group sizes, considerably less than lifetime exposure, and only
limited histopathological examination. Dermal and subcutaneous injection cancer studies found
no evidence for tumorigenicity of chloroacetic acid (Van Duuren et al., 1974; BRL, 1968), but
were not adequate bioassays. There is some evidence from genotoxicity studies that chloroacetic
acid has potential to produce genetic effects. Chloroacetic acid has been shown to induce
forward mutations in L5178Y cells in vitro and sister chromatid exchanges in Chinese hamster
ovary cells (NTP, 1992). Chloroacetic acid also was positive in an in vivo sperm abnormality
assay in mice and produced positive results in an in vivo chromosome aberrations assay (NTP,
1992; Bhunya and Das, 1987). Due to questions regarding interpretation of the negative cancer
bioassays available for chloroacetic acid, and data indicating that the chemical has some
genotoxic potential, the negative bioassays are not considered to represent sufficient evidence of
noncarcinogenicity. Therefore, under the proposed U.S. EPA (1999) cancer guidelines, the
available data are inadequate for an assessment of human carcinogenic potential.
REFERENCES
ACGIH (American Conference of Governmental Industrial Hygienists). 2002. 2002 Threshold
Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices.
ACGIH, Cincinnati, OH.
ATSDR (Agency for Toxic Substances and Disease Registry). 2002. Internet HazDat-
Toxicological Profile Query. Online, http://www.atsdr.cdc.gov/toxpro2.html
20

-------
11-24-2004
Bhat, H., M. Kanz, G. Campbell, and G. Ansari. 1991. Ninety day toxicity study of chloroacetic
acids in rats. Fund. Appl. Toxicol. 17(2): 240-253.
Bhunya, S.P. and P. Das. 1987. Bone marrow chromosome aberration and sperm abnormality in
mice in vivo induced by chloroacetic acid. Chromosome Information Service. 0(42): 28-30.
BRL (Bionetics Research Labs). 1968. Evaluation of carcinogenic teratogenic and mutagenic
activities of selected pesticides and industrial chemicals. Vol. 1. Carcinogenic study prepared by
BRL Inc for NCI, August, 1968. NTIS Publ. No. 223-1159. (Cited in U.S. EPA, 1988a)
Bryant B., M. Jokinen, S. Eustis et al. 1992. Toxicity of monochloracetic acid administered by
gavage to F344 rats and B6C3F1 mice for up to 13 weeks. Toxicology. 72(1): 77-87.
Daniel F., M. Robinson, J. Stober et al. 1991. Ninety-day toxicity study of sodium
monochloroacetate in Sprague-Dawley rats. Toxicology. 67:171-185.
DeAngelo, A., F. Daniel, B. Most and G. Olson. 1997. Failure of monochloroacetic acid and
trichloroacetic acid administered in the drinking water to produce liver cancer in male F344/N
rats. J. Toxicol. Environ. Health. 52: 425-445.
Feldhaus, K., D. Hudson, R.S. Rogers et al. 1993. Pediatric fatality associated with accidental
oral administration of monochloroacetic acid (MCA). Vet. Hum. Toxicol. 35:344. (Cited in
WHO, 1998)
IARC (International Agency for Research on Cancer). 2002. Search of IARC Monographs.
Online. http://193.51.164.il/cgi/iHound/Chem/iH Chem Frames.html
IRDC (International Research and Development Corporation). 1982a. Subchronic oral toxicity
test with monochloroacetic acid in rats. National Toxicology Program, Bethesda, MD.
Document 5705-303.
IRDC (International Research and Development Corporation). 1982b. Subchronic oral toxicity
test with monochloroacetic acid in mice. National Toxicology Program, Bethesda, MD.
Document 5705-307.
Johnson P., B. Dawson and S. Goldberg. 1998. Cardiac teratogenicity of trichloroethylene
metabolites. J. Am. Coll. Cardiol. 32(2): 540-545.
Kulling P., H. Andersson, K. Bostrom et al. 1992. Fatal systemic poisoning after skin exposure
to monochloroacetic acid. Clin. Toxicol. 30:643-52. (Cited in WHO, 1998)
21

-------
11-24-2004
Maksimov, G.G. and O.N. Dubinina. 1974. Materials for experimental substantiation of
maximally permissible concentration of monochloroacetic acid in the air of production area.
Gig. Tr. Prof. Zabol. 9: 32-35. (Rus.; Eng. summary, Cited in U.S. EPA, 1988a).
NIOSH (National Institute for Occupational Safety and Health). 2002. Online NIOSH Pocket
Guide to Chemical Hazards. Index by CASRN. Online.
http://www.cdc.gov/niosh/npg/npgdcas.html
NTP (National Toxicology Program). 2003. Management Status Report. Online.
http://ntp-server.niehs.nih.gov/cgi/iH Indexes/ALL SRCH/iH ALL SRCH Frames.html
NTP (National Toxicology Program). 1992. Toxicology and Carcinogenesis studies of
monochloroacetic acid (CAS No. 79-11-8) in F344/N rats and B6C3F1 mice (Gavage studies).
NTP Technical Report 396. NIH Publication No. 92-2851.
OSHA (Occupational Safety and Health Administration). 2002. OSHA Standard 1910.1000
Table Z-2. Part Z, Toxic and Hazardous Substances. Examined December 19, 2002. Online.
http://www.osha-slc.gov/OshStd data/1910 1000 TABLE Z-2.html.
Rogers D. 1995. Accidental fatal monochloroacetic acid poisoning. Am J. Forens. Med. Pathol.
16:115-16. (Cited in WHO, 1998)
Smith, M.K., J.L. Randall, E.J. Read and J.A. Stober. 1990. Developmental effects of
chloroacetic acid in the Long-Evans rat. Teratology. 41:593.
U.S. EPA. 1988a. Health and Environmental Effects Document (HEED) for chloroacetic acid.
Prepared by the Environmental Criteria and Assessment Office, Office of Health and
Environmental Assessment, Cincinnati, OH for the Office of Solid Waste and Emergency
Response, Washington, DC.
U.S. EPA. 1988b. Recommendations for and Documentation of Biological Values for Use in
Risk Assessment. Prepared by the Environmental Criteria and Assessment Office, Office of
Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH.
PB88-17874. EPA/600/6-87/008.
U.S. EPA. 1991. Chemical Assessments and Related Activities (CARA). Office of Health and
Environmental Assessment, Washington, DC. April.
U.S. EPA. 1994. Chemical Assessments and Related Activities (CARA). Office of Health and
Environmental Assessment, Washington, DC. December.
22

-------
11-24-2004
U.S. EPA. 1997. Health Effects Assessment Summary Tables (HEAST). FY-1997 Update.
Prepared by the Office of Research and Development, National Center for Environmental
Assessment, Cincinnati, OH for the Office of Emergency and Remedial Response, Washington,
DC. July. EPA/540/R-97/036. NTIS PB97-921199.
U.S. EPA. 1999. Proposed Guidelines for Cancer Risk Assessment. July. Office of Research
and Development, National Center for Environmental Assessment, Cincinnati, OH.
U.S. EPA. 2003a. Integrated Risk Information System (IRIS). Office of Research and
Development. National Center for Environmental Assessment, Washington, DC. Online.
http://www.epa. gov/ iris/
U.S. EPA. 2002b. Drinking Water Standards and Health Advisories. Summer 2002. Office of
Water, Washington, DC. Online, http://www.epa.gov/ost/drinking/standards/
Van Duuren, B.L., B.M. Goldschmidt, C. Katz et al. 1974. Carcinogenic activity of alkylating
agents. J. Natl. Cancer Inst. 53:695-700.
WHO (World Health Organization). 1998. Poison Information System (PIM) 352.
Monochloroacetic acid. Online, http://www.inchem.org/documents/pims/chemical/pim352.htm
WHO (World Health Organization). 2002. Online catalogs for the Environmental Health
Criteria Series. Online, http://www.who.int/dsa/cat98/chemtox8.htm#
23

-------