2-methyl-3-butenenitrile

Endpoint summary

Description of key information

Oral: LD50 (males/rats): 232 mg/kg bw 
Dermal: LD50 (males/ rats): 482 mg/kg bw
Inhalation:LC50 (male rats/4h) : 9.95 mg/L

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

232 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

9 950 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

482 mg/kg bw

Additional information

Acute toxicity: oral

Only one study is available and is identified as the key study (Rondot, 1981). 2 -methyl-3 -butenenitrile (2M3BN) was tested for acute oral toxicity similarly to OECD test guideline No. 401. Groups of Sprague-Dawley rats (5/sex/group) were administered by gavage a single dose of 2M3BN in aqueous suspension of 10% arabic gum at doses of  0, 400, 480, 580 and 700 mg/kg bw and observed for 14 day. Clinical signs include reduced activity, apathy and ptosis. Gross pathology include haemoragic digestive tract and lungs in the animals died during the sutdy, thickening of the peritoneum. The Combined LD₅₀ =   459 mg/kg bw (95% confidence limits: 380 -555 mg/kg bw), the LD50 (males) = 232 mg/kg bw and the LD50 (females) is 622 mg/kg bw. The male was more sensitive than the female rat. Therefore, the LD50/oral/ rat (males) was chosen for this endpoint, considering as the worst case.

Acute toxicity: dermal

Two studies were selected as key studies (Rondot, 1981 and ). In the first study, 2 -methyl-3 -butenenitrile (2M3BN) was tested for acute dermal toxicitysimilarly to the OECD test guideline No. 402. Groups of Sprague-Dawley rats (5/sex/group) were exposed to 2M3BN for 24 hours at doses of 0, 1500, 1750, 2000 and 2500 mg/kg bw and observed for 14 days. Clinical signs include reduced activity, apathy and ptosis. No signs of irritation were observed. Gross pathology include haemorrhagic lung and thymus in the animals died during the study.

The Combined LD₅₀= 1849 mg/kg bw (95% confidence limits: 1533 -2231 mg/kg bw).

In the second study (Kennedy, 1983), the test substance (2 -methyl-3 -butenenitrile 74 % and 2 -methyl-2 -butenenitrile18%) was applied under a gauze pad to the intact skin of four groups of six adult male New Zealand White rabbits at dose levels of 250, 325, 400 and 700 mg/kg bw, for 24 hours. The rabbits were clipped free of hair over the back and trunk area and fitted plastic collars. The rabbits were observed and/or weighed daily (except weekends) over a 14-day recovery period and then sacrified. Loss of weight was observed at all dose levels tested, prostration at 700 mg/kg bw and weakness at 400 and 700 mg/kg bw. All death occured within one day after dosing, at 325 mg/kg bw and above.

The LD50 of tested substance administered to the intact skin of male rabbits was 482 mg/kg bw.

 

Acute toxicity: inhalation

In an acute toxicity study selected as the key study (Anonymous, 1970), 2 -methyl-3-butenenitrile was administered to six ChR-CD male rats by inhalation way at 3000 ppm for four hours. Gross and histopathologic examinations were performed on two rats each 1, 2, 7 and 14 days post-exposure. The other survivors were sacrified 14 days post-exposure. Clinical signs observed in the rats indicated an effect on the central nervous system. First death occured within 3.5 hours.

In the test conditions of this study, LC 50/rat (male)/4 h = 3000 ppm (9.95 mg/L).

Justification for classification or non-classification

Based on the key studies (cited above), a following self - classification is proposed:

- 2-methyl-3-butenenitrile is classified in Category 3 (H301: Toxic if swallowed) according to the Regulation 1272/2008/EC and as harmful if swallowed (Xn, R22) according to the Directive 67/548/EEC.

- 2-methyl-3-butenenitrile is classified in Category 3 (H311: Toxic in contact with skin) according to the Regulation 1272/2008/EC and as harmful in contact with skin (Xn, R21) according to the Directive 67/548/EEC.

- 2 -methyl-3-butenenitrile was classified in category 3 (H331: Toxic if inhaled) according to the CLP regulation and as harmful if inhaled (Xn, R20) according to the Directive 67/548/EEC.