Chloroacetic acid

Endpoint summary

Description of key information

Key study (NTP): 13 -week study in rats according to OECD 408, LOAEL 30 mg/kg bw (not used in DNEL derivation).

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

August 1981-November 1981

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Principles of method if other than guideline:

OECD 408 study, however, no information in document on ophthalmoscopy, neurobehavioral tests and food consumption.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: F344/N

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River breeding laboratories, Inc. Portage, MI
- Age at study initiation: 6-7 weeks
- Weight at study initiation: males 140 gram, females 112 grams
- Fasting period before study:-
- Housing: 5/cage, polycarbonate cages
- Diet (e.g. ad libitum): ad libitum (NIH-07 open formula mash diet)
- Water (e.g. ad libitum): automatic watering system, ad libitum
- Acclimation period:13 days

ENVIRONMENTAL CONDITIONS
- Temperature: 74.2 °F
- Humidity (%): 38.9%
- Air changes (per hr): 10-12 changes/hour
- Photoperiod (hrs dark / hrs light): 12 hrs light / 12 hours dark

IN-LIFE DATES: From: 17 August 1981 To: 17 November 1981

Route of administration:

oral: gavage

Details on route of administration:

Dose volume 5 mL/kg.

Vehicle:

water

Remarks:

Deionised

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 0, 6.0, 12.0, 18.0, 24.0 and 30.0 mg/mL, dose volume 5 mL/kg
- Amount of vehicle (if gavage): not specified

PREPARATION OF DOSING SOLUTIONS:
Dose formulations were prepared by mixing appropriate amounts of MCAA and deionized water to obtain required concentrations
Formulations were stored at room temperature for a maximum of 2 weeks

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses on the monochloroacetic acid dose formulations were conducted twice, and confirmed that the dose formulations were within 10% of the target concentrations; values ranged from -9% to +8% of target concentration.
The method involved diethylether extraction and subsequent flame ionisation gas chromatography using nitrogen as the carrier gas, ether as diluent, and decanol as an internal standard.

Stability analyses on 3 mg/mL solutions on three occasions during a 2-year study confirmed the stability for at least 3 weeks.
The method involved dilution of the dose formulations with acetonitrile and injection into a GC-FID equipped with a 1.8 x 2 mm ID column packed with 10% SP-1200/1% H3PO4 in 100/120 mesh Supelcoport; a column temperature of 135 degrees C and a N2 carrier flow rate of 30 mL per minute.

Duration of treatment / exposure:

13-weeks
(for interim animals 4 and 8 weeks respectively)

Frequency of treatment:

5 days/week

Dose / conc.:

30 mg/kg bw/day (actual dose received)

Dose / conc.:

60 mg/kg bw/day (actual dose received)

Dose / conc.:

90 mg/kg bw/day (actual dose received)

Dose / conc.:

120 mg/kg bw/day (actual dose received)

Dose / conc.:

150 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

20 animals/sex/group

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on 16-day range finding study
- Rationale for animal assignment (if not random): by computerized random number generator
- Section schedule rationale (if not random): not specified
5 animals/sex/group were killed at week 4 and 8 for haematology, clinical chemistry and urinalysis parameters.

Positive control:

not applicable

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: checked twice daily for morbidity and mortality

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice in week 1 and weekly thereafter: signs of toxicity and palpated for masses

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly

HAEMATOLOGY: Yes
- Time schedule for collection of blood: weeks 4, 8 and at end study
- Anaesthetic used for blood collection: No data (animals were killed for sampling)
- Animals fasted: assumed yes (animals for clin chem were fasted)
- How many animals: Weeks 4 and 8: 5/sex/group, at end of study, all surviving
- Parameters examined: rbc, wbc, diff leuco count, haematocrit, Hb, MVH, MCHC, MCV and metHb, bone marrow smears made.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood:weeks 4, 8 and at end study
- Animals fasted: Yes
- How many animals: Weeks 4 and 8: 5/sex/group, at end of study, all surviving
- Parameters were examined. electrolytes, Na, K, chloride, phosphorus, Calcium, BUN, creatinine, total bilirubin, ASAT, ALAT, LDH, total protein, albumin, alb-glob ratio, cholinesterase, ornithine carbamyl transferase, sorbitol dehydrogenase, triiodothyronine and thryoxin

URINALYSIS: Yes
- Time schedule for collection of urine: weeks 4, 8 and at end study
- Metabolism cages used for collection of urine: Yes
- Animals fasted: assumed yes (animals for clin chem were fasted)
- Parameters examined: color, appearance, specific gravity, pH, protein, glucose, occult blood, nitrites, urobilinogen, ketones, and bilirubin

NEUROBEHAVIOURAL EXAMINATION: Not specified

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
necropsy on all animals not killed at 4 or 8 weeks for evaluation of haematologic and clinical chemistry parmaters. organ weights of brain, heart, liver, lungs, right kidney, adrenal gland, right testis and thymus were reorded for all animals surviving until the end of the study.
HISTOPATHOLOGY: Yes
Complete evaluation of all animals that died before termination and on all survivors in control, 60, 90, 120 and 150 mg/kg group. Heart, lungs, bronchi and liver were examined for rats in the 30 mg/kg group.
Tissues examined microscopically: adrenal gland, aorta, brain, cecum, colon, duodenum, esophagus, gross lesions, heart, jejunum, ileum, kidney, liver, lungs and bronchi, lymph nodes, mammary gland, nose, ovaries, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, rectum, salivary gland, spleen, sternum with marrow, stomach, testis, thymus, thyroid gland, trachea, tissue masses, urinary bladder and uterus.

Other examinations:

Electron microscopy to detect peroxisome proliferation, performed in selected animals

Statistics:

Body weight, organ weights: Dunn's or Shirley's test
Haematology, clinical chemistry, urinalysis: Dunn's or Shirley's test; Jonckheere trend test

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not specified

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
All rats in the 120 and 150 mg/kg bw/day group, 19/20 in the 90 mg/kg bw/day group, and 2 males and 1 female in the 60 mg/kg bw/day group died before the end of the study. Given the high mortality in the highest dose groups, the results are mainly reported for the 0, 30, and 60 mg/kg bw/day groups. No clinical findings noted
HAEMATOLOGY
Hematocrit, hemoglobin, and erythrocyte counts were increased in male rats receiving 150 mg/kg bw/day for 4 weeks. Neutrophil counts were increased in males given 90, 120, and 150 mg/kg bw/day for 4 weeks. After 8 weeks of MCAA administration, lymphocyte counts were decreased in males of the 30, 60, 90, and 120 mg/kg bw/day groups.
CLINICAL CHEMISTRY
Blood urea nitrogen was doserelated increased at 90 to 150 mg/kg bw/day in males and at 60 to 150 mg/kg bw/day in females. There was a dose-related increase in ASAT and ALAT in males and females at 60 to 150 mg/kg bw/day. The increases were not statistically significant at all dose levels and all time points. Thyroxin (T4) levels were increased in male rats at 90, 120, and 150 mg/kg bw/day in week 4 and at 90 mg/kg bw/day in week 8. Serum cholinesterase activity was decreased in males at 30
and 60 mg/kg bw/day after 13 weeks, in all female dose groups after 4 and 8 weeks, and in females of the 60 mg/kg bw/day group after 13 weeks. The decreased serum cholinesterase activity may have been a result of liver toxicity, or direct inhibition of this enzyme by MCAA or its metabolites. In addition, females showed decreased plasma levels of total protein (from 30 mg/kg bw/day), albumin (at 60 mg/kg bw/day), calcium (30 and 60 mg/kg bw/day), and sodium (from 30 mg/kg bw/day) after 8 and/or 13 weeks. Plasma potassium was increased after 13 weeks at 60 mg/kg bw/day in females and at 30 and 60 mg/kg bw/day in males.
ORGAN WEIGHTS
Absolute heart weight was decreased at 60 mg/kg bw/day in both sexes, while relative heart weight was decreased at 60 mg/kg bw/day in males and at 30 and 60 mg/kg bw/day (dose-related) in females. Absolute liver weight was increased at
60 mg/kg bw/day in males and relative liver weight was increased at 30 and 60 mg/kg bw/day (dose-related) in males and at 60 mg/kg bw/day in females. Relative kidney weight was increased at 30 and 60 mg/kg bw/day (dose-related) in males.
GROSS PATHOLOGY
Rats that died in the study showed blood or clear red fluid in thoracic cavity and congestion of lungs was observed.
HISTOPATHOLOGY
Treatment-related and dose-related cardiomyopathy (acute or subacute) was considered the cause of death in the decedents. Degenerative and inflammatory changes (cardiomyopathy) noted in hearts of male and female rats receiving 60, 90, 120 or 150 mg/kg. Lesions occurred primaily in the myocardium of the left ventricular wall and interventricular septum. EM examination on selected animals revealed no evidence of peroxisome proliferation.

Dose descriptor:

LOAEL

Effect level:

30 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Decreased relative heart weight (females), increased relative kidney weight (males), increased relative liver weight, and decreased cholinesterase activity at 30 mg/kg bw/day

Critical effects observed:

not specified

Conclusions:

LOAEL at 30 mg/kg, which is lowest dose tested. At 30 mg/kg decreased relative heart weight (females), increased relative kidney weight (males), increased relative liver weight, and decreased cholinesterase activity.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEL

30 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

Subacute and subchronic studies available in both rats and mice

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The 90 -day study in rats provided a LOAEL of 30 mg/kg bw, based on decreased relative heart weight (females), increased relative kidney weight (males), increased relative liver weight, and decreased cholinesterase activity at 30 mg/kg bw/day. However, a NOAEL of 3.5 mg/kg bw for systemic effects is availabe from a 2 -year carcinogenicity study.

Justification for classification or non-classification

The 90 -day key study provided an oral LOAEL of 30 mg/kg bw; a two-year carcinogenicity study (see section 7.7) provided a NOAEL of 3.5 mg/kg bw.