Mercaptoacetic acid

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 April to 19 May 1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

no

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Mercaptoacetic acid

EC Number:

200-677-4

EC Name:

Mercaptoacetic acid

Cas Number:

68-11-1

Molecular formula:

C2H4O2S

IUPAC Name:

2-sulfanylacetic acid

Details on test material:

Test compound: Thioglycolic acid
CAS no.: 68-11-1
Source: SNEA(P)
Batch: 82503
Purity: 99.05%
Storage: 4°C in the dark

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Test animals:
- Species: Rat Strain: Crl:CD(SD)BR
- Age: 4 to 6 weeks old
- Weight at dosing: 104-146 g
- Source: Charles River UK Lim., Margate, Kent UK
- Acclimation period: 7 days
- Diet: Labsure LAD 1, ad libitum
- Water: Tap water, ad libitum
- Housing: Animals were housed in groups by sex in stainless steel  suspended cages

Environmental conditions:
- Temperature: 23-26°C
- Humidity: 51 %
- Air changes: 15 air change/hour
- Photoperiod: Alternating 12-hour light and dark cycles

Rats were fasted overnight before treatment and 4 hours after treatment.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Doses:

40, 64, 80, 200 mg/kg

No. of animals per sex per dose:

40

Control animals:

no

Details on study design:

Animal assignment and treatment: Following a range-finding preliminary test, dose levels of 40, 64, 80 and  200 mg/kg were selected for the main study.  Five males and 5 females were assigned to each test groups. Following an  overnight fast, rats were given a single dose of thioglycolic acid by  gavage. The test substance was administered in distilled water at a  volume of 20 ml/kg bw. 

Animals were observed for gross toxicity,  behavioural changes and/or mortality soon after dosing and at frequent  intervals for the remainder of day 1 and at least once daily for the  remainder of the 14-day study. Body weights were recorded at day 1 (day  of dosing), 8 and 15 and at death. On day 14, surviving animals were  sacrificed and all animals were necropsied and examined for gross  pathological changes.

Statistics:

The LD50 was calculated using the method of Finney (1971) Probit analysis  (3rd Ed.) Cambridge University Press.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LD50

Effect level:

73 mg/kg bw

Based on:

act. ingr.

95% CL:

67 - 81

Gross pathology:

Autopsy of rats that died revealed slight renal pallor in one male and female at 80 mg/kg.  Terminal autopsy findings were normal.

Any other information on results incl. tables

- Number of deaths at each dose level

                     Mortality
Dose level        Male                Female
(mg/kg)                
40                0/5                0/5
64                1/5                0/5
80                3/5                5/5
200               5/5                5/5
- Time of death : 
 200 mg/kg : 3 males & 3 females at 4 hours and 2 males and
2 females at 6 hours,  80 mg/kg : 2 males and 3 females at 5 hours, 1  female at 7 hours, 1 male and 1 female at 24 hours,  64 mg/kg : 1 male at  24 hours.

- Signs of reaction to treatment
-------------------------------------------------------------------
                 No. of rats in group of 5 showing signs
                 ----------------------------------------
Dose (mg/kg)               40         64         80         200
Signs                     M  F        M  F        M  F        M  F
-------------------------------------------------------------------
Piloerection              5  5        5  5        5  5        5  5
Hunched posture           5  5        5  5        5  5        5  5
Waddling                 5  5        5  5        5  5        5  5
Lethargy                 5  5        5  5        5  5        5  5
Pallor of
extremities               5  5        5  5        5  5        5  5
Decrease
respiration rate          2  0        5  5        5  5        5  5
Ptosis                    0  0        5  5        5  5        5  5
Prostration               0  0        1  0        4  2        5  5   
---------------------------------------------------------------------

Applicant's summary and conclusion

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

Under these experimental conditions, the LD50 is 73 (67-81) mg/kg

Executive summary:

In an acute oral toxicity study performed according to the OECD guideline # 401, 5 groups of 5 Sprague-Dawley rats per sex were dosed with 0, 40, 64, 80 and 200 mg/kg bw thioglycolic acid (purity 99%). Animals were observed for 14 days following the exposure for mortality and clinical signs. Mortality occurred at dose levels equal to and exceeding 64 mg/kg bw. Behavioural abnormalities (piloerection, lethargy, ptosis, prostration) were observed in all treated rats. The LD₅₀of thioglycolic acid was 73 mg/kg bw.