Appendix D - Dossier (PDF) - Tera

date: 20–JUL–2005
5. Toxicity Substance ID: 71–43–2
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Type: other: Absorption
Remark: Benzene concentrations in inhaled and exhaled air and in
blood and urine were followed for 2 to 3 hr. in 27
experimental studies on 23 human subjects who inhaled
benzene vapors in concentrations of 150 to 350 ug. per
liter(47 to 100 ppm). The rate of absorption of benzene is
highest in the first few minutes of inhalation (70 to 80
percent); afterward it drops quickly and in the majority of
cases stays at 50 percent during the test period. During
the test period an equilibrium between blood and air levels
of benzene was not achieved. In the desaturation period 30
to 50 percent of the absorbed benzene is eliminated by the
lungs, while the quantity of benzene eliminated by the
kidneys is insignificant (0.1 to 0.2 percent), and the
elimination continues for a long time. Benzene which is
notexcreted by the lungs or the kidneys remains in the body
andis metabolized (50 to 70 percent, exceptionally more).
On the basis of the experimental results, the decrease of
the quantities of benzene in the blood and the exhaled air
was calculated during the desaturation period, and it was
found that both quantities are related to the actual
quantity of benzene in the blood, according to a logarithmic
curve. Theratio between the rate constants of desaturation
in blood and exhaled air is near to 1.
Source: Deutsche Shell Chemie GmbH Eschborn ;German rapporteur
Flag: Risk Assessment
14–SEP–2000 (1082)
Type: other: Absorption
Remark: Nude mice each attached to a respirator to avoid pulmonary
uptake were exposed in a glass exposure chamber to 200,
1000or 3000 ppm of benzene, for 2, 4 or 6 h. The animals
were killed at the end of the study and the amount of
benzene retained in the whole body was determined by gas
chromatography. Skin absorption rates were calculated from
the amount retained in the whole body using the single
compartment model (elimination rate constant) obtained in a
previous experiment. There was a linear relationship
between the amount of skin absorption and exposure time,
andalso a linear relationship between the skin absorption
rate and concentration of exposed vapors. Skin absorption
of benzene occurs by passive diffusion as defined by Fick’s
law. The skin absorption coefficient (cm/h) of benzene
vapor was calculated by dividing the skin absorption rate
byexposure concentration; the value was 0.619 for benzene.
The coefficient may be useful for evaluating the amount of
skin absorption of solvent vapors in the work environment.
Source: Deutsche Shell Chemie GmbH Eschborn ;German rapporteur
Flag: Risk Assessment
14–SEP–2000 (1164)
Appendix D: Benzene SIDS Dossier
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