Registration Dossier
Registration Dossier
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EC number: 295-405-4 | CAS number: 92045-23-3 A complex combination of hydrocarbons produced by the distillation of the products of a steam cracking process. It consists predominantly of hydrocarbons having a carbon number of C4, predominantly 1-butene and 2-butene, containing also butane and isobutene and boiling in the range of approximately minus 12°C to 5°C (10.4°F to 41°F).
Immunotoxicity
Administrative data
Description of key information
Members of the C4 high 1,3-butadiene category show low potential for immunotoxicity. No persistent immunological defects were detectable after inhalation exposure to the constituent substance 1,3-butadiene at 1250 ppm (2765 mg/m3).
Key value for chemical safety assessment
Additional information
Studies on the effects on the immune are available for one of the constituent substances of the C4 high 1,3-butadiene category (1,3-butadiene).The effect of 1,3-butadiene on immune function in mice was investigated by Thurmond et al (1986). B6C3F1 Mice were exposed to 1250 ppm (2766 mg/m3) 1,3-butadiene by inhalation 6 h/day, 5 days/ week, for 6 or 12 weeks. Immune function assays were selected to evaluate specific humoral and cell-mediated immunity and spontaneous cytotoxicity, lymphoid organ histopathology was also evaluated. Significant extramedullary haematopoiesis and erythroid hyperplasia was observed in spleens from exposed mice, and correlated with a two-fold increase in thymidine incorporation in spontaneously proliferating splenocytes. Cytotoxic T-lymphocyte generation was suppressed after a 6-week exposure to 1,3-butadiene, but was comparable to controls after 12 weeks of exposure. Overall, no persistent immunological defects were detectable after inhalation exposure to 1250 ppm (2765 mg/m3) 1,3-butadiene.
Justification for classification or non-classification
Members of the C4 high 1,3-butadiene category are flammable gases at room temperature and therefore dermal and oral exposure is unlikely. They have low sub-chronic inhalation toxicity and studies which included evaluation of immunotoxicity parameters indicate low potential for immunotoxicity. Classification under CLP is not warranted.
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