Registration Dossier

Administrative data

Description of key information

oral LD50 (rat): ca. 4900 mg/kg bw (key study: Wolf et al., 1956)
inhalation LC50 (6 hrs; rat): ca. 22850 mg/m3 (key study: Monsanto Co., 1972)
dermal LD50 (NZW rabbit): ca. 14560 mg/kg bw (key study: Union Carbide Co., 1975)

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
4 900 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
22 850 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
14 560 mg/kg bw

Additional information

Oral toxicity

For alpha-methylstyrene no studies performed according to recent guidelines are available. However, the available studies, which have some limitations concerning documentation or low number of animals in study are indicating very low acute toxicity.

LD50 (rat): 4900 mg/kg bw (Wolf et al., 1956)

LD50 (rat): 2840 mg/kg bw (Monsanto Co., 1972)

LD50 (rat): ca. 5915 mg/kg bw (Union Carbide Co., 1975)

LD50 (rat): > 7940 to < 10000 mg/kg bw (Union Carbide Co., 1970)

Toxic signs were unspecific and included reduced appetite and activity, weakness, ocular discharge, collapse and death and died animals showed hyperaemia of lungs and liver and acute GI inflammation.

Dermal toxicity

For alpha-methylstyrene no studies performed according to recent guidelines are available. However, the available studies, which have some limitations concerning documentation or low number of animals in study are indicating very low acute toxicity.

LD50 (rabbit): ca. 14560 mg/kg bw (Union Carbide Co., 1975)

MLD (rabbit): > 7940 mg/kg bw (Monsanto Co., 1970, 1972)

Toxic signs included reduced appetite and activity, weight loss, skin erythema, and hiccup-like spasms.

Inhalation toxicity

For alpha-methylstyrene no studies performed according to recent guidelines are available. However, the available studies, which have some limitations concerning documentation or low number of animals in study are indicating very low acute toxicity.

LC50 (rat; 6 hrs): ca. 22850 mg/m3 (Monsanto Co., 1972)

rats with an exposure to ca. 41600 mg/m3 over 8 hrs: 2/6 animals died during the exposure (Union Carbide Co., 1975)

Toxic signs included lethargy and collapse and the necropsy of survivors showed slight congestion of lungs, while necropsy of died animals showed haemorrhagic lungs, slight liver discoloration, and acute GI inflammation.

Justification for classification or non-classification

Based on the available and reliable data there is no classification of alpha-methylstyrene for acute toxicity (oral, dermal and inhalation) based on EU regulation 1272/2008.