CMP

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:

other: GLP compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment. GLP-deviation: the stability of the test substance has not been reported.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2000

Report date:

2000

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

435-030-7

EC Name:

-

Cas Number:

26452-81-3

Molecular formula:

C5H5N2OCl

IUPAC Name:

4-chloro-6-methoxypyrimidine

Test material form:

other: solid

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: Males 260 - 360 g; females 180 - 215 g
- Fasting period before study: No
- Housing: Individually, in cages suitable for animals of this strain and the weight range expected during the course of the study
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days prior to dosing

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 - 70
- Air changes (per hr): ≥15
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Type of coverage:

occlusive

Vehicle:

water

Details on dermal exposure:

TEST SITE
- Area of exposure: dorso-lumbar region
- Type of wrap if used: a foil backed gauze patch, held in position by a cohesive bandage secured with two pieces of surgical tape.

REMOVAL OF TEST SUBSTANCE
- Washing: absorbent cotton wool soaked in clean warm water and dried with clean tissue paper
- Time after start of exposure: 24 hours

TEST MATERIAL
- Amounts applied: 500, 750 or 1000 mg/kg
- Constant volume or concentration used: no
- For solids, paste formed: yes

VEHICLE
- Amount applied: 0.2 - 0.4 mL

Duration of exposure:

24 hours

Doses:

500, 750, 1000 mg/kg

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: observations: prior to dosing, at least twice following dosing on day 1, thereafter once daily. Weighing on day of dosing (day 1) and days 8 and 15.
- Necropsy of survivors performed: yes, macroscopic examination.

Statistics:

For males, the acute dermal median lethal dose was estimated from the mortality data (the mortality data included animals that were killed in extremis) by linear log-dose interpolation using nominal dose values. Confidence limits are given by the highest dose with no mortalities and the lowest dose with 100% mortality,
For females, the acute dermal median lethal dose was estimated from the mortality data (the mortality data included animals that were killed in extremis) by logistic regression using nominal dose values. Confidence limits were calculated using a likelihood ratio interval.

Results and discussion

Effect levels

Effect levels 1

Sex:

male

Dose descriptor:

LD50

Effect level:

612 mg/kg bw

Based on:

test mat.

95% CL:

500 - 750

Effect levels 2

Sex:

female

Dose descriptor:

LD50

Effect level:

709 mg/kg bw

Based on:

test mat.

95% CL:

606 - 828

Mortality:

Following a dose of 500 mg/kg, none of the animals died.
Following a dose of 750 mg/kg, all the males were killed in extremis on days 1 or 2 and three of the females were found dead on day 2.
Following a dose of 1000 mg/kg, all the animals were killed in extremis on day 1.

Clinical signs:

other: Following a dose of 500 mg/kg, signs of slight systemic toxicity were seen in all animals, with decreased activity, lacrymation, salivation and upward curved spine observed in most animals. Other signs such as miosis, stains around mouth and nose and side

Gross pathology:

Following a dose of 500 mg/kg, there were no macroscopic abnormalities at examination post mortem.
Following a dose of 750 mg/kg, there were no macroscopic abnormalities in the surviving animals. One male and one female had an eye discharge. The same male and another female had stained nares and one female had a discoloured thymus. These are all non-specific findings but are considered to be treatment-related. One male had a white deposit in the bladder which is considered to be a spontaneous finding and unrelated to treatment.
Following a dose of 1000 mg/kg, one male had a discoloured thymus. As above, this is a non­specific, but treatment-related finding. Two males had pelvic dilatation of the kidney which is considered to be a spontaneous finding and unrelated to treatment.

Applicant's summary and conclusion

Interpretation of results:

Toxicity Category IV

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute dermal median lethal dose of the test substance is estimated to be 612 mg/kg and 709 mg/kg to male and female rats respectively.

Executive summary:

In this acute dermal toxicity study in rats, according to OECD guideline 402, and GLP, groups of five male and five female Alpk:APrSD (Wistar-derived) rats received a single dermal application of 500, 750 or 1000 mg/kg of test substance. Test substance was moistened to a dry paste with a small amount of water and applied to shaved skin and kept in contact with skin using an occlusive dressing for approximately 24 hours after which the skin was cleansed free of test substance. Surviving animals were assessed daily for the following 14 days for any signs of systemic toxicity and their body weights were recorded at intervals of 1 week throughout the study. Animals in extremis and those surviving to the end of the study were killed and, together with those found dead, were subjected to a macroscopic examination. Following a dose of 500 mg/kg, none of the animals died. Signs of slight systemic toxicity were seen in all animals, with complete recovery by day 4. All animals showed an overall body weight gain during the study. There were no macroscopic abnormalities. Slight skin irritation was seen in three males and all the females, but had completely resolved by day 13. Following a dose of 750 mg/kg, all the males were killed in extremis on days 1 or 2 and three of the females were found dead on day 2. The surviving females showed signs of slight systemic toxicity, with complete recovery by day 3; both showed an overall body weight gain during the study. At examination postmortem, treatment-related abnormalities were seen in one male and the three females killed in extremis and comprised eye discharge, staining of the nares, and discolouration of the thymus. There were no macroscopic abnormalities in the surviving females. Slight skin irritation was seen on day 2 in one male. Following a dose of 1000 mg/kg, all the animals were killed in extremis on day 1. At examination postmortem one male had a discoloured thymus. In conclusion, the acute dermal median lethal dose of the test substance is estimated to be 612 mg/kg (95% confidence limits 500, 750) to male rats and 709 mg/kg (95% confidence limits 606, 828) to female rats.