GB/T 15670.5-2017Toxicological test methods for pesticides registration—Part 5: Acute dermal toxicity test (English PDF)

3.1 Acute dermal toxicity

The health-damaging effect of skin exposure to the test substance resulting from continuous exposure for 24 hours.

3.2 Dose

The amount of the test substance provided, which is expressed in terms of the mass of the test substance received per unit body weight of the experimental animal (mg/kg body weight).

3.3 Median lethal dose; LD50

After the test substance is administered to the experimental animals once or multiple times within 24 hours, the statistical dose of toxicant that causes the death of half of the experimental animals. It is expressed in terms of the mass of the test substance received per unit body weight of the experimental animal (mg/kg body weight).

3.4 Dose-response relationship

The relationship between dose and the occurrence of a specific effect.

6.1 Preparation of Test Substances

Liquid test substances generally use the original solution. Solid test substances shall be ground into powder and pass through a 100-mesh sieve, and thoroughly moistened with water or other non-toxic, non-irritating media that do not affect skin permeability and do not react with the test substance, so as to ensure good contact between the test substance and the skin.

6.2 Experimental Animals

6.2.1 Species and weight

Rats are preferred, but white rabbits, white guinea pigs or non-rodent animals can also be selected. Reasons for selecting experimental animals other than rats shall be explained. The required weight ranges for experimental animals are respectively. rats 200 g ~ 300 g, white rabbits 2.0 kg ~ 3.0 kg, and guinea pigs 350 g ~ 450 g. Common domestic strains can also be selected. Female animals shall be non-pregnant and nulliparous.

6.2.2 Animal gender

Select animals of the most sensitive gender for test. When uncertain, the test results of animals of both genders can be provided.

6.5.2.2 Weighing

Animal weights shall be weighed and recorded before exposure, after exposure (at least once a week) and before execution.

6.5.3 Pathological examination

During the test period, animals that died of poisoning and humanely killed animals shall be grossly dissected, and the gross pathological changes of each animal shall be recorded. If the organs of animals that survive for 24 hours or more after exposure show gross pathological changes, then, histopathological examination is required to obtain information regarding the toxic effects. If necessary, conduct histological examination of the skin in the poisoned area and adjacent non-infected areas.

7.1 Result Processing

7.1.1 Utilize a table to list all the original data of each group (two genders or single gender) of animals obtained in the test. The content shall include animal No., gender, dose of poison, weight, presence and extent of various physical signs, death or survival status, presence and extent of each lesion during gross anatomy and histopathological examination.

7.1.2 Respectively count the number of animals in each group and of different genders, the occurrence of physical signs, death, survival, and the frequency of various lesions in gross anatomy and histopathological examination. Calculate the occurrence of the above-mentioned items in different groups and different genders of animals, and the average body weight at different times.

7.1.3 Use appropriate statistical methods to conduct statistical analysis on the above-mentioned data.

7.1.4 Use appropriate methods to calculate LD50 and 95% confidence interval.

7.2 Result Evaluation

7.2.1 Make a preliminary evaluation of whether the test substance can be absorbed through the skin and its toxic effects.

7.2.2 For the toxic effect level of the test substance, if the dose-reaction relation curve can be obtained, a preliminary evaluation of the acute dermal toxic effect threshold can be made.

7.2.3 Specify the gender of the animals and the exposure time for which the toxicity parameters are obtained.

7.2.4 The acute dermal toxicity level is determined in accordance with the corresponding standards in 3.3.2.8 of Regulations on Pesticides Registration Information.