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EC number: 265-073-5
CAS number: 64741-70-4
A complex combination of hydrocarbons obtained from catalytic isomerization of straight chain paraffinic C4 through C6 hydrocarbons. It consists predominantly of saturated hydrocarbons such as isobutane, isopentane, 2,2-dimethylbutane, 2-methylpentane, and 3-methylpentane.
Inhalation: Absorption of the constituents of gasoline tends to
increase with increasing molecular weight with straight chain molecules
being more highly absorbed than branched isomers and aromatic molecules
being more highly absorbed than paraffins (Dahl et al., 1988). Thus,
butane and most of the pentane isomers are very poorly absorbed and if
absorbed are rapidly exhaled. Absorption of isobutene
was estimated as 14% in humans and 5.4% in rats (Galvin and Bond, 1999a). Rodent
data indicate that approximately 5% of neopentane, 9% of isopentane and
19% of n-pentane are absorbed (Galvin and Panson, 1999a; Galvin and
Maraschi, 1999a; Galvin and Marashi, 1999b). Approximately
35% of inhaled cyclopentane is absorbed. Approximately
20% of inhaled n-hexane is absorbed (ATSDR, 1999). Absorption
is estimated as 23-78% for cyclohexane, 50% for benzene, 50% and for
toluene. As an overall approximation it would be
reasonable to assume that in both humans and animals, approximately 15%
of the C3 to C5 constituents, 25% of the hexanes and approximately 50%
of the remainder would be absorbed. Higher molecular
weight constituents are not expected to contribute substantially to
inhalation exposure (Mckee et al., 2000).
Oral: It would be reasonable to assume that
approximately 100% of ingested gasoline and naphtha constituents would
Dermal: The percutaneous absorption of gasoline
and naphtha constituents is difficult to assess because of the volatile
nature of these substances. Material applied to the
skin typically vaporizes quickly with limited absorption. Conversely
when material is applied to the skin under conditions that prevent
evaporation, such as the use of occluded patches, substantially higher
levels of absorption have been measured. Using benzene
as an example, as summarized by Brainard and Beck (1993), in dermal
penetration studies that utilized occlusive patches, benzene absorption
approached 100%, but if the benzene was simply allowed to evaporate from
the skin, the fraction absorbed was closer to 1%.
Regardless of the route by which they were absorbed, gasoline and
naphtha constituents are rapidly metabolized and eliminated. The
alphatic constituents are generally metabolized to the corresponding
alcohols (Galvin and Marashi, 1999a; 1999b; 1999c; Galvin and Panson,
1999a; 1999b; 1999c; Galvin and Bond, 1999b). The
metabolism of benzene is more complex, beginning with the formation of
benzene oxide. There are several possible succeeding
pathways leading to phenyl mercapturic acid, phenol, catechol or
muconaldehyde. Higher aromatics are primarily
metabolized by side chain oxidation to benzyl alcohols and ultimately
All of the gasoline and naphtha constituents are hydrophobic, indicating
a higher affinity for adipose than other tissues, although there are
differences in distribution of the individual constituents depending on
their specific physical and chemical properties. None
of the constituents is considered to be an accumulative substance.
The lower molecular weight gasoline and naphtha constituents are
primarily excreted by exhalation, either in their metabolized or
un-metabolized forms (Galvin and Bond, 1999a). Overall
biological half times for these constituents are typically measured in
minutes (McKee et al., 1998). Cyclohexane is also
primarily eliminated, unchanged in the exhaled air. Metabolites
of other constituents are primarily excreted as urinary metabolites with
biological half times on the order of 3-5 hours based on blood
measurements and up to 12 hours based on urinary excretion data (Verma,
Additional references on gasoline constituents:
Galvin J, Bond G
Journal of Toxicology and Environmental Health Part A 58:3-22.
J, Bond G (1999b). 2-Methylpentane,
Journal of Toxicology and Environmental Health Part A 58:81-92.
J, Bond G (1999c). 3-Methylpentane,
Journal of Toxicology and Environmental Health Part A 58:93-102.
J, Marashi F (1999a). 2-Methylbutane
of Toxicology and Environmental Health Part A 58:23-34.
Galvin J, Marashi F
Journal of Toxicology and Environmental Health Part A 58:35-56.
J, Marashi F (1999c). Cyclopentane,
Journal of Toxicology and Environmental Health Part A 58:57-74
J, Panson R (1999a). Neopentane,
Journal of Toxicology and Environmental Health Part A 58:75-80.
J, Panson R (1999b). 2,2-Dimethylbutane,
Journal of Toxicology and Environmental Health Part A 58:103-110.
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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