(S)-2-chloropropionic acid

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Remarks:

other: See attached paper under methods

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1982

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Full methodology described in the paper, although GLP status unknown

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1982

Report date:

1982

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Weanling rats were maintained on pulverized Wayne Lab-Blox for 1 week before the drugs were added to their diet. Rats were randomly assigned to one of three groups: control (Lab-Blox alone), dichloroacetate-treated (0.04 mol/kg of feed) or 2-chloropropionate-treated (0.04 mol/kg of feed). There were six male rats in each group. The drugs were administered by mixing the sodium salts of the drugs with the pulverized feed and allowing the rats to feed ad libitum. Body weights were determined weekly and food consumption was measured daily. After 12 weeks animals were sacrificed and tissue specimens taken from testes, kidney and other organs were fixed, sectioned and stained (H&E) for histological examination.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 2-chloropropionate

EC Number:

241-067-8

EC Name:

Sodium 2-chloropropionate

Cas Number:

16987-02-3

Molecular formula:

C3H5ClO2.Na

IUPAC Name:

sodium 2-chloropropanoate

Details on test material:

Tested substance was Sodium 2-Chloropropionate, CAS Number 16987-02-3, EC Number 241-067-8.

2-Chloropropionic acid was neutralised with sodium hydroxide prior to use.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

Male Wistar rats were obtained from Harlan Industries or Cox Laboratory Supply Company (Indianapolis). Animals were kept in the facilities of the Indiana University Laboratory Animal Resource centre and fed Wayne LabBlox ad libitum.

Administration / exposure

Route of administration:

oral: feed

Details on oral exposure:

Sodium 2-Chloropropionate was mixed with pulverised feed (Lab-Blox) [0.04 mol/kg of feed) and the rats allowed to feed ad libitum.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

The rats were allowed to feed ad libitum for 12 weeks

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0 mmol/kgbw/day (control)
Basis:
nominal in diet

Doses / concentrations 2

Remarks:

Doses / Concentrations:
4 mmol/kg bw/day
Basis:
nominal in diet

No. of animals per sex per dose:

Six animals

Control animals:

yes, plain diet

Details on study design:

Male rats only were used. Weanlings were acclimatized for one week before being fed test diets at constant incorporation rate. There is no indication that any clinical pathology investigations were performed and at termination the tissue list was restricted to testes, kidney “and other organs”. These latter included at least brain and peripheral nerve as results from these are reported. Organs weighed were adrenals, brain, heart, kidneys, liver, lungs, prostate (ventral), spleen, testes (with epididymides) and thyroid.

Results and discussion

Results of examinations

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

effects observed, treatment-related

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Description (incidence and severity):

No lesions were reported.

Histopathological findings: non-neoplastic:

not specified

Description (incidence and severity):

In all six treated rats there was evidence of arrest of testicular maturation and degeneration of germ cells. Some seminiferous tubules were lined with Sertoli cells only. Histologically prostate was unaffected.

Histopathological findings: neoplastic:

not specified

Description (incidence and severity):

None

Details on results:

BODY WEIGHT AND WEIGHT GAIN
Bodyweight was stated as recorded weekly, but only the terminal bodyweights and total bodyweight gains are reported. In the group fed 2-chloropropionic acid, terminal bodyweights are approx. 70% of control while bodyweight gain was approx 63% of control values. These indicate that the maximum tolerated dose was clearly exceeded by some considerable margin.

FOOD EFFICIENCY
Food consumption was reported to be recorded daily, but only total consumption over the full period of the study is reported in the publication. Food efficiency was reported as unaffected, although the calculated value is slightly in excess of control.

NEUROBEHAVIOUR
Hind limb weakness and abnormal gait were observed in treated animals within 2-4 weeks after the test diets were offered.

ORGAN WEIGHTS
Brain weight, heart weight, kidneys weight, liver weight, spleen weight, testes plus epididymides weight were all significantly reduced compared to controls. Adrenals and thyroid weights were comparable to controls. The weight of ventral prostate was only about 65% of control value, although the difference was not claimed as statistically significant. When adjusted for bodyweight only heart and testes plus epididymides weights were significantly reduced compared to control. As expected, some organs showed a statistically significant increase in organ:bodyweight ratio, notably brain and adrenals, reflecting the fact that these weights are not generally closely correlated with bodyweight.

GROSS PATHOLOGY
No lesions were reported.

HISTOPATHOLOGY: NON-NEOPLASTIC
In all six treated rats there was evidence of arrest of testicular maturation and degeneration of germ cells. Some seminiferous tubules were lined with Sertoli cells only. Histologically prostate was unaffected.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
None.

OTHER FINDINGS
There was no clinical pathology performed in this study. The range of tissues taken for histological examination was not detailed. However, in the discussion of the paper it is claimed only that 2-chloropropionate caused a decrease in plasma-triglyceride levels with no significant change in serum ketone bodies. This is probably an indirect effect resulting from the severely depressed bodyweight gain of these rats. Although clinical signs of neurotoxicity were seen there is no evidence of histological change at least in the organs examined.

Effect levels

Remarks on result:

not determinable

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Hind limb weakness and abnormal gait were observed within 2 to 4 weeks. Weights of liver, spleen, kidneys, heart, testes plus epididymides and brain were significantly less that in the control group. The organ:body weight ratios were significantly larger than the corresponding control ratios for adrenals and lungs. Sodium 2-chloropropionate inhibited growth of testes as evidenced by the fact that the ratio of the weight of testes plus epididymides to the body weight was significantly smaller than in the control group. Degeneration of germ cells was also observed.

Applicant's summary and conclusion

Conclusions:

A rat feeding study was conducted using male rats only. At the selected dose levels, which declined from approx 430 to approx 270 mg/kg/day during the course of the study , the only clinical signs recorded were hind limb weakness and abnormal gait. Organ weight changes were mainly attributable to the depressed weight gain. However, the substance caused testicular abnormalities were are probably indicative of a delayed maturation reflecting the severe depression of bodyweight gain of these rats.

Executive summary:

A feeding study was conducted in six male rats by mixing the substance with pulverised feed at 0.04 moles substance/kg feed which was fedad libitumfor 12 weeks. Received doses declined from approx 430 mg/kg/day at the start of the study to 270 mg/kg/day at the end. Hind limb weakness and abnormal gait were observed within 2-4 weeks. Weights of liver, spleen, kidneys, heart, testes plus epididymides and brain were significantly less than in the control group. Prostate weights were approx 65% of control value, although the difference was not statistically significant. When organs:bodyweights were considered, only the testes plus epididymides weight was depressed compared to the control with increases for adrenals and lungs, although these organs are not notably sensitive to bodyweight change. It was reported that 2-chloropropionate-treated rats had significantly lower plasma triglycerides than controls, although this probably reflects the depressed bodyweight rather than a specific effect. Histologically the reduced testicular weight accompanied by arrested maturation and degeneration of germ cells, possibly reflected the substantially reduced bodyweight.

It is evident that the single dose tested was well in excess of the maximum tolerated dose so that any conclusions drawn must be tentative.