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EC number: 295-458-3
CAS number: 92045-76-6
A complex combination of hydrocarbons obtained from residual oils by solvent crystallisation and treated with hydrogen in the presence of a catalyst. It consists predominantly of saturated straight and branched chain hydrocarbons having carbon numbers predominantly greater than C25.
The acute toxicity of paraffin and hydrocarbon waxes is low with no observed mortalities from oral (OECD 401/420) or dermal (OECD 402) applications.
hydrocarbon waxes have low acute toxicity with an oral LD50greater
than 5000 mg/kg (in rat) and a dermal LD50of greater than
2000 mg/kg (in rabbit). Inhalation
toxicity studies were not reported for paraffin and hydrocarbon waxes,
as inhalation is not an expected route of exposure due to the very low
vapour pressure and high boiling point of these substances.
In an acute oral
toxicity study (International Bio-Research, 1976a, b, Klimisch score =
1), paraffin wax in Arachis oil diluent and microcrystalline wax in
Arachis oil diluent, were tested in rats (5/sex/dose) at dose levels
ranging from 1000 to 5000 mg/kg. The
rats were observed for clinical signs of toxicity for the following 7
days and then weighed, killed and autopsied. There
were no mortalities or clinical signs of toxicity during the observation
period. Growth rates
were normal, and no microscopic changes were observed at autopsy. The
LD50was concluded to be greater than 5000 mg/kg. The
study was conducted prior to promulgation of GLP guidelines but was
considered a well-conducted study.
supporting studies (Elder 1984, Klimisch score=2), acute oral toxicity
tests on various formulations of paraffins ranging from 5% to 16% did
not produce any mortality and the LD50s were greater than 60
ml/kg, 5000 mg/kg, and 10000 mg/kg in rats and an LD50of
greater than 25 ml/kg in beagle dogs. Acute
oral tests on 4.35% and 20% microcrystalline waxes produced LD50s
in rat greater than 25000 mg/kg and 10000 mg/kg, respectively.
Additional acute oral toxicity studies in rats (BIBRA Toxicology
International, 1993a; BIBRA Toxicology International, 1993b) also
reported LD50s >5000 mg/kg body weight.
In an acute
dermal toxicity study (Shell International Petroleum Mij.B.V, 1993),
groups of five male and five female young adult Sprague-Dawley rats were
dermally exposed to Paraffin wax (SX30) for 24 hours to approximately
10% of body surface at a dose of 2000 mg/kg body weight. Animals then
were observed for 14 days. The test article caused slight skin
irritation reactions in a majority of treated animals which persisted
throughout the study. However, a previous study performed at BIBRA
(Report No.1091(3) /1/93) demonstrated that SX30 is only a mild irritant
and has no corrosive (irreversible) properties when applied to intact
rabbit skin for 24 hours. Based on this the dermal LD50 was calculated
to be >2000 mg/kg body weight. Supporting dermal toxicity data in
rabbits (CTFA, 1972 and Elder, 1984) indicate that paraffin and
hydrocarbon waxes have LD50s >3600 mg/kg.
Justification for selection of acute toxicity – oral endpoint
One of 11 acute oral toxicity studies showing similar results
Justification for selection of acute toxicity – dermal endpoint
one of 2 acute dermal studies showing similar results
Paraffin and hydrocarbon waxes do not meet
the EU criteria for acute oral or dermal toxicity and are therefore not
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