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EC number: 265-057-8
CAS number: 64741-56-6
A complex residuum from the vacuum distillation of the residuum from atmospheric distillation of crude oil. It consists of hydrocarbons having carbon numbers predominantly greater than C34 and boiling above approximately 495°C (923°F).
petroleum vacuum residue 81 -13 was tested in a 28-day dermal toxicity
study in NZW rabbits. Four groups of 5 male and 5 female rabbits were
exposed to sample 81 -13 of vacuum residue once per day, three days/week
for 4 weeks (12 applications in total). Doses applied were 0
(sham-exposed), 200, 1000 or 2000 mg/kg body weight. The neat material
was slightly heated just prior to application to decrease its viscosity,
put on a 4 x 4 inch patch and subsequently applied to shaven dorsal skin
and occluded. After 6 hours the patch was removed and any remaining test
material was wiped off using gauze; however, the test material was not
completely removed. Body weight was recorded prior to the first
application and from then on weekly. Each day the application area on
the skin was examined and scored for erythema and oedema (Draize
scores). Scoring for erythema proved difficult due to residual material
on the skin that prevented observance of the colour of the skin. At the
end of the study, all animals were sacrificed for clinical chemistry,
haematology and histopathology investigations.
vacuum residue sample 81-13, one
male from the high-dose group and one female from the control group died
on days 9 and 3, respectively. These early decedents had no antemortem
signs and hence these deaths were not considered treatment related. One
male from the control group and one female from the intermediate-dose
group were found moribund and sacrificed on days 6 and 10, respectively.
Both animals showed paralysis of the hind limbs the day prior to the
sacrifice. These deaths were also not considered treatment-related, but
rather as the result of trauma during dosing and wrapping.
Treatment-related findings were flaking skin, wheezing and a decreased
food-intake (qualitative observation) resulting in less body weight gain
in the exposed groups compared to controls. The lesser body weight gain
was statistically significant in the high-dose males as
compared to the control group. No treatment-related trends were observed
in either clinical chemistry or haematology investigations. No
treatment-related effect on reproductive organs were noted. Treatment
related effects were observed in the skin of most high-dose males and
females with very slight to slight oedema observed after the first
treatment and consistent in all animals as of day 16 until the last day
(day 28). In the intermediate-dose groups (1000 mg/kg) some animals
showed slight oedema until day 10; as of day 11 almost all animals
showed very slight to slight oedema until the end of the study. In the
low-dose group (200 mg/kg) most males showed oedema in the last two
weeks and most females in the last week of treatment. Gross pathology
findings of reddened or thickened skin, were consistent with the
microscopic observations of skin effects: minimal to moderate subacute
acanthotic dermatitis and minimal to moderate hyperkeratosis.
LOEL for vacuum residuum was 200 mg/kg/day, based on mild skin
irritation and the absence of histopathological findings and the value
of 200 mg/kg/d was taken forward to calculate the DNEL for dermal local
NOEL for systemic effects was 1000 mg/kg, based on body weight effects.
As there were no clinical or histopathological findings, the decreased
body weight was considered to be secondary to the reduced food intake
and the value of >2000 mg/kg/d was taken forward to calculate the DNEL
for dermal systemic effects.
study received a Klimisch score of one and is classified as reliable
without restrictions because it was an acceptable study that was well
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