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Administrative data

Description of key information

Acute oral studies in Rats (Fisher 344 and Wistar), Acute dermal study in Rabbits

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
2 000 mg/kg bw

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
2 000 mg/kg bw

Additional information

Acute oral toxicity:

Two studies are available for this substance. Different strains of rats and different dose ranges were used. In the first study, Fisher 344 rats (male and female) were dosed with DPnP (no vehicle) at 500, 2500 and 5000 mg/kg bw. At 500 mg/kg tehre were no mortalities, at 2500 mg/kg there were 3/5 male deaths and 4/5 female deaths. At 5000 mg/kg bw, all rats died.

In the second study using Wistar rats, a single dose level of 2000 mg/kg bw was dosed to 5 male and 5 female rats. One male died on day 1 after dosing, but there were no other mortalities.

Although a linear extrapolation to the LD50 value using the results of the first study would provide an estimate of LD50s for male and female rats of 2030 and 1500 mg/kg respectively, the absence of female mortality at 2000 mg/kg bw in the second study would indicate that the linear extrapolation may not be appropriate in this case. It is appreciated that different strains of rats were used, however the weight of evidence would support that the LD50 of this substance is likely to be greater than 2000 mg/kg.

Acute Dermal toxicity:

5 New Zealand white rabbits per sex were dosed dermally (occlusive conditions) with 2000 mg/kg bw. No mortality was observed therefore the LD50 is >2000 mg/kg bw.

Acute Inhalation toxicity:

No inhalation data are available for this substance, however given the low level of toxicity observed via the oral and dermal routes of exposure, it is considered unlikely that the LD50 via inhalation would lead to a classification for inhalation toxicity.

Justification for classification or non-classification

The weight of evidence from the available acute oral toxicity studies indicates that the LD50 value for this substance is likely to be greater than 2000 mg/kg bw but less than 2500 mg/kg bw. As such no classification for acute oral toxicity is required according to CLP. Classification as Category 5 for acute oral toxicity according to GHS is appropriate in those regions employing this additional acute toxicity category.

No mortality was observed at 2000 mg/kg bw dosed dermally to rabbits. As such the LD50 is considered to be >2000 mg/kg bw.