Teflubenzuron

Endpoint summary

Description of key information

Acute oral toxicity:

LD50 >5000mg/kg bw

Acute inhalative toxicity:

LD50 >5038 mg/kg bw

Acute dermal toxicity:

LD50 >2000mg/kg bw

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 5 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

> 5 038 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 2 000 mg/kg bw

Additional information

Acute oral toxicity:

In an acute oral toxicity study in Wistar rats according to OECD Guideline 401 and GLP, the test substance was administered via gavage in polyethylene glycol at 5000 mg/kg bw to 5 males and 5 females. No mortality was found over the course of 15 days, the expected body weight gain was observed. Clinical signs included sedation, hunched posture and ruffled fur in the first 24 hours following application. No macroscopic changes were reported following necropsy at the end of the study period. Therefore, the LD50 in rats was determined as >5000 mg/kg bw.

These findings are supported by a non-GLP OECD guideline 401 study in Wistar rats (no RSS included in IULCID, but can be provided if requested), in which the test substance was administered at 1000 or 5000 mg/kg bw in 2% CMC as gavage to 5 males and 5 females per dose group. No mortality was observed in the course of 14 days and the expected body weight gain was recorded. Clinical signs observed were ruffled fur at 1000 mg/kg bw and ruffled fur as well as dyspnea at 5000 mg/kg bw. All clinical signs were resolved within 3 days following substance application. Gross pathology reported mottled lungs in 3/5 males in the 1000 mg/kg bw group, the other rats showed no macroscopic organ changes. Therefore, the LD50 in rats was determined as >5000 mg/kg bw under the conditions tested.

In an acute oral toxicity study in NMRI mice according to OECD guideline 401 and GLP, the test substance was administered via gavage in polyethylene glycol at doses of 1000 or 5000 mg/kg bw to 5 males and 5 females per dose. No mortality was observed over the course of 14 days, the expected body weight gain was recorded. No clinical signs were observed at 1000 mg/kg bw, in the 5000 mg/kg bw group dyspnea and ruffled fur were observed within the first 4 days following application. No gross organ changes were recorded at necropsy at the end of the study period. Therefore, the LD50 in mice was determined at >5000 mg/kg bw.

 

Acute inhalation toxicity:

The acute inhalation toxicity of the test substance was evaluated in a study according to OECD guideline 403 and GLP. Wistar rats were exposed to a dust aerosol of the test substance over 4 hours. The mean test substance concentration was analytically determined to be 5038 mg/m3, gravimetrical analysis of particle size showed that approx. 38% of the determined particles were within the range of 1-7 µm. No mortality was observed over the course of 14 days. Dyspnea and ruffled fur was observed in all rats, starting within 2 hours of exposure. All animals recovered within 2 days after start of exposure. The body weight gain was unaffected by the test substance treatment and gross pathology did not reveal any macroscopic organ changes. Therefore, the LC50 in rats was determined to be >5.038 mg/L.

 

Acute dermal toxicity:

The acute dermal toxicity of the test substance was tested in a study according to OECD guideline 402 and GLP in Wistar rats. The test substance was suspended in polyethylene glycol and applied to a 20 cm2 patch of shaved (clipped) skin at 2000 mg/kg bw. The site was covered with occlusive dressing and the test substance was removed with water 24 hours after application. No mortality was observed over the course of 14 days, the expected body weight gain was recorded. No clinical signs or gross pathology findings at necropsy were reported. Therefore, the dermal LD50 in rats was determined as >2000 mg/kg bw.

The finding that the substance is practically non-toxic following single dermal application are supported by another study conducted according to JMAFF guideline in New Zealand White rabbits. The report is only available in Japanese, however the abstract is provided in English. Due to the limited detail provided in the abstract, these data can only be considered supporting. The test substance was applied moistened with water to a 12 x 14 cm previously shaved test site at doses of 1000 and 2000 mg/kg bw for 24 hours. No mortality, clinical signs or abnormalities regarding body weights or gross pathology were observed. Therefore, the dermal LD50 in rabbits was >2000 mg/kg bw under the conditions tested.

Justification for classification or non-classification

Based on the data available and laying down the criteria specified in Regulation (EC) 1272/2008, no classification for acute toxicity is warranted.