Methomyl

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: Ministry of Agriculture, Forestry and Fisheries of Japan 12-Nouan-8147

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Methomyl

EC Number:

240-815-0

EC Name:

Methomyl

Cas Number:

16752-77-5

Molecular formula:

C5H10N2O2S

IUPAC Name:

(E)-[1-(methylsulfanyl)ethylidene]amino N-methylcarbamate

Test material form:

solid: crystalline

Specific details on test material used for the study:

- Substance name: Methomyl Technical
- Substance ID: DPX-X1179
- Lot#: X1179-599
- Purity: 99.6%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Remarks:

albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Ace Animals, Inc., Boyertown, Pennsylvania
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: Young adult (8-9 weeks)
- Weight at study initiation: Males 259-273 grams and females 189-217 grams
- Housing: One animal per cage
- Diet: Purina Rodent Chow #5012
- Water: ad libitum
- Acclimation period: 9 days

ENVIRONMENTAL CONDITIONS
- Temperature: 19-22°C
- Humidity: 46-67%
- Photoperiod: 12-hour light/dark cycle

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

water

Details on dermal exposure:

TEST SITE
- Area of exposure: Dorsal area and the trunk
- % coverage: Approximately 10% of the body surface
- Type of wrap: 3-inch Durapore tape

REMOVAL OF TEST SUBSTANCE
- Washing: Test sites were gently cleansed of any residual test substance
- Time after start of exposure: 24 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 1.3-1.9 g
- For solids, paste formed: Yes

Duration of exposure:

24 hours

Doses:

5000 mg/kg body weight

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The animals were observed for mortality, signs of toxicity, and behavioral changes 1 and 5 hours after application and at least once daily thereafter for 14 days. Individual weights of the animals were recorded prior to test substance application (initial) and again on Days 7 and 14 (termination).
- Necropsy of survivors performed: Yes
- Examinations performed: Observations included gross evaluation of skin and fur, eyes and mucous membranes, respiratory, circulatory, autonomic and central nervous systems, somatomotor activity and behavior pattern. Particular attention was directed to observation of tremors, convulsions, salivation, diarrhea, and coma. Gross necropsies were performed on all animals. Tissues and organs of the thoracic and abdominal cavities were examined.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

All animals survived during the study

Clinical signs:

other: Erythema was observed at the application site of one female on Day 1 following patch removal. There were no signs of gross toxicity, adverse clinical signs, or abnormal behavior.

Gross pathology:

No gross abnormalities were noted for any of the animals when necropsied at the conclusion of the 14-day observation period.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

LD50 (Rat): > 5000 mg/kg bw

Executive summary:

An acute dermal toxicity test was conducted with rats to determine the potential for test substance to produce toxicity from a single topical application. This study was conducted according to OECD guideline 402 and OPPTS 870.1200.

Five thousand milligrams of the test substance per kilogram of body weight was moistened with distilled water and then applied to the skin of ten healthy rats (five male and five female) for 24 hours. The animals were observed for mortality, signs of toxicity, and behavioral changes 1 and 5 hours post-dosing and at least once daily for 14 days. Body weights were recorded prior to application and again on Days 7 and 14. Necropsies were performed on all animals at terminal sacrifice.

All animals survived and gained body weight during the study. Erythema was observed at the application site of one female on Day 1 following patch removal. There were no signs of gross toxicity, adverse clinical signs, or abnormal behavior. No gross abnormalities were noted for any of the animals when necropsied at the conclusion of the 14-day observation period.

Under the conditions of this study, the single dose acute dermal LD50 of the test substance is greater than 5000 mg/kg of body weight in male and female rats.