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EC number: 203-449-2
CAS number: 106-98-9
Members of the butenes category are flammable gases at room temperature and therefore the requirement for data on acute oral and dermal toxicity is waived in accordance with REACH Annex XI. Members of the butenes category have low acute inhalation toxicity. The LC50 for 2-butene is excess of 10,000 ppm (22,948 mg/m3).
requirement for data on acute oral and dermal toxicity is waived in
accordance with REACH Annex XI, as members of the butenes category are
flammable gases at room temperature. Members of the butenes category
have low acute inhalation toxicity. The acute inhalation toxicity of
2-butene has been determined in a key OECD 403 guideline study. An LC50
in excess of 10,000 ppm (22,948 mg/m3) (the lower explosive
limit) after 4h inhalation exposure was reported. No clinical signs were
seen and normal growth occurred over the 14 day observation period. No
abnormalities were observed at gross necropsy. Only one concentration of
2-butene was tested (TNO 1992a). The low acute toxicity of 2-butene by
inhalation is consistent with the low acute inhalation toxicity of
2-methylpropene. LC50s in rats of 620,000 mg/m3 (4h exposure) and mice
415,000 mg/m3 (2h exposure) respectively were reported for
2-methylpropene (Shugaev 1969). These results are also supported by data
from Virtue (1950). 1-Butene, cis and trans 2-butene and 2-methylpropene
at 27.2, 25.5, 21 and 32% (approximately 623,000; 580,000, 480,000 and
734,000mg/m3) respectively produced respiratory arrest in mice after
exposure for 10 min. No clinical observations were seen, other than
narcosis, during or after exposure. The butenes have the potential to
produce narcosis or cause asphyxia by reducing the available
concentration of oxygen at butene concentrations above the lower
There are no acute toxicity data in humans.
Justification for selection of acute toxicity – inhalation
No deaths have occurred in experimental animals exposed to butenes
up to the lower explosion limit. While some studies have indicated
asphyxia and death at higher concentrations, methodological or reporting
limitations call into question the derivation of an LC50. In any case,
such a value would be meaningless with respect to explosion hazard, and
is beyond the threshold for classification for acute toxicity.
Members of the butenes category are
flammable gases at room temperature and therefore inhalation exposure is
the only relevant route. Category members are of low acute toxicity by
the inhalation route with LC50 values in excess of 10,000 ppm (22,948
mg/m3) (the lower explosive limit). Category members therefore do not
warrant classification under GHS/CLP.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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