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EC number: 306-005-7
CAS number: 95465-90-0
Members of the C4 low 1,3-butadiene 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. There are no specific studies on the streams in this category (CAS Numbers; 91052-98-1, 92045-23-3, 95465-89-7, 95465-90-0 and 95465-91-1) but data on the component substances (butane, isobutane and butene isomers) indicate that the acute inhalational toxicity of this category is low. The LC50 values for all substances are in excess of 10,000 ppm (22,948 mg/m3) and butane and isobutane are considered to be Generally Recognised as Safe and may be used in food products.
The requirement for data on acute oral and
dermal toxicity is waived in accordance with REACH Annex XI, as members
of the C4 low butadiene category are flammable gases at room
The acute inhalational toxicity of streams
in this category is expected to be low.
There are no specific studies on the streams
in this category (CAS Numbers; 91052-98-1, 92045-23-3, 95465-89-7, 95465-90-0
and 95465-91-1) but data are
available on the component substances. The acute inhalational toxicity
of all these component substances is low. In all cases LC50 values
exceed the dose levels which would warrant classification under DSD or
CLP. Limited human data also support this conclusion. The category
members have the potential to produce narcosis or cause asphyxia by
reducing the available concentration of oxygen. Intentional inhalation
(abuse) of high concentrations of butane can cause symptoms including
euphoria, ataxia, nausea, convulsions, coma, respiratory depression, and
Specific data are as follows:
Butane: LC50 values of 658,000 mg/m3in rats
and 680,000 mg/m3 in mice were reported (Shugaev et al 1969). Toxicity
included anaesthesia, CNS depression, cardiac sensitisation (all rapidly
reversible if exposure ceases).
Isobutane: No toxic effects were noted below
its lower flammability limit of 18000 ppm (42787 mg/m3). Aviado et al
(1977) reported the 2 hour LC50 in mice to be 52% (approximately 520,400
ppm or 1237 mg/L), but the same authors tested a mixture of 3
hydrocarbons (isobutane, butane, and propane) and found the LC50 of the
mixture comparable to isobutane alone at 57.42% (approximately 539,600
ppm). Both Aviado et al (1977) and Clark and Tinston (1982) demonstrated
the range of concentrations required to cause CNS depression/
anaesthesia and those concentrations causing mortality is narrow. There
was also evidence of cardiotoxicity including cardiac sensitisation,
decreases in both pulmonary compliance and tidal volume but again at
dose levels far exceeding the lower flammability limit.
Butene isomers (butenes): An LC50 in excess
of 10,000 ppm (22,948 mg/m3) has been reported for 2-butene in rats (TNO
1992a). No clinical signs were seen and normal growth occurred over the
14 day observation period. No abnormalities were observed at gross
necropsy. 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
Butane and isobutane: Are considered by the
US Food and Drug Administration to be Generally Recognised as Safe
(GRAS) when used as propellants, aerating agents and gases and can be
used in food products (PHPV 2001). In
a controlled exposure study, Stewart et al (1977, 1978) exposed adult
volunteers to isobutane and isobutane/propane mixtures at concentrations
of 250-1000 ppm (594 -2377 mg/m3) for 1 min to 8 hours. No subjective or
physiological responses were reported. Fatality data are reported for
butane where inhalation occurs as a result of intentional misuse. Butane
gas may be inhaled during intentional misuse. The acute effects of human
solvent abuse include euphoria, disinhibition, hallucinations, ataxia,
nausea, convulsions, coma, tinnitus, cardiac arrhythmias, respiratory
depression, and even death. Death may ensue by direct cardiac toxicity
(arrhythmias) or central nervous system toxicity (respiratory
depression) or indirectly by hypoxia (bag over head), aspiration of
vomit or trauma. The Netherlands Health Council (2004) also summarise
several individual cases or retrospective studies in which butane was
identified as the fatally toxic agent.
Butene isomers (butenes): There are no acute
toxicity data in humans.
of the C4 low 1,3-butadiene category are flammable gases at room
temperature and therefore inhalation exposure is the only relevant route.There
are sufficient data available on component substances to conclude that
streams within the
C4 low 1,3-butadiene category are of low acute toxicity by the
inhalation route with LC50 values in all cases exceeding the doses which
would warrant classification under Dir 1999/45/EC or 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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