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EC number: 200-756-3
CAS number: 71-55-6
The volatile nature of 1,1,1-trichloroethane means that dermal exposure is likely to be limited, unless occluded. In humans, the potential for dermal irritation is associated with the duration of exposure and irritancy is unlikely following accidental spillage on to the skin, providing the test substance is removed immediately. In vitro results suggest that if skin contact is maintained there is the potential for cellular damage and this is confirmed in animal studies.An OECD 404 study in rabbits found 1,1,1-trichloroethane to be irritating, but other studies suggest that the dermal reaction is mild.Ocular irritation is slight when tested in the rabbit. Reports from humans exposed to 1,1,1-trichloroethane also confirm mild ocular irritation.
The volatile nature of
1,1,1-trichloroethane means that dermal exposure is unlikely to be
prolonged unless it is occluded. A
review of the literature suggests dermal exposure to
1,1,1-trichloroethane causes either no effects or reversible effects in
who immersed their thumbs in beakers of undiluted 1,1,1-trichloroethane
for 30 minutes reported mild burning pain after .10 minutes of exposure
(Stewart 1964). Following exposure, mild erythema and fine scaling were
visible on the thumb; there was no increase in severity after 30 minutes
and the observations were reversible within one hour.
Repeated application to the
exposed forearm (Wahlberg 1984), daily for 10 days, produced no visible
signs of reaction and no measurable thickening of the skin.
However, an in vitro test for
skin irritancy (OECD 431), using both the direct method and the patch
method on reconsititued human skin, found
1,1,1-trichloroethane to be irritant. Following
4 hours exposure cell viability was reduced, IL-1α release was increased
and histology showed notable necrosis (Tornier 2006). In
humans, the potential for dermal irritation is associated with the
duration of exposure and irritancy is unlikely following accidental
spillage on to the skin, providing the test substance is removed
vitro results suggest that if skin contact is maintained there is the
potential for cellular damage..
Assessments of the skin irritancy of
1,1,1-trichloroethane in animals reveal slight to moderate reactions. In
the majority of the animals studies contact of 1,1,1-trichloroethane
with the skin in maintained by artificial means. A
robust study conducted at TNO (1990), following the OECD 404 guideline,
found 1,1,1-trichloroethane to be irritating to the rabbit following 4
hours semi-occlusive exposure; signs of severe erythema and oedema were
fully reversible. Based
on single-application studies in rabbits, 1,1,1-trichloroethane was
ranked as a moderate skin irritant by Duprat et al. (1976). Torkelson et
al. (1958), however, reported only slight reddening and scaliness of
rabbits' skin following a single application. Irritation observed
following repeated application of the compound for 10 days was only
slightly more noticeable and quickly disappeared after the end of
treatment (Torkelson et al. 1958). Kronevi
et al. (1981) studied cellular changes produced in the intact skin of
guinea pigs by exposure to 1 mL of undiluted 1,1,1-trichloroethane under
a cover glass for durations ranging from 15 minutes to 16 hours.
Prolonged exposure for several hours caused severe inflammatory
reactions in the upper part of the dermis, the extent of which increased
Although extended dermal contact with
relatively concentrated 1,1,1-trichloroethane may cause irritation and
burning sensations of the skin of humans, most evidence in humans and
animals indicates that this compound is not a strong skin irritant,
unless exposure is prolonged.
An eye irritation study in the rabbit,
instilling 0.1 mL of 1,1,1-trichloroethane, and scoring according toe
Kay and Calandra, found the substance to be only slightly irritating
(Duprat 1976). Similar
results were observed by Torkelson (1958). Humans
briefly exposed to high 1,1,1-trichloroethane vapour concentrations
reported only mild eye irritation (ATSDR 2006)
Based on the available animal data, the TNO study, which follows the
OECD 431 guidelines for skin irritation, 1,1,1 -trichloroethane was
found to be skin irritant as mean scores of 4 were observed in the test.
Therefore a classification of skin irritant category 2 is supported.
Moreover 1,1,1-trichloroethane was found to be slightly irritating to
eye and therefore falls under class 2B Mild Irritant.
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