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Percutaneous penetration of benzene in hairless mice: an estimate of dermal absorption during tire-building operations.

Susten AS; Dames BL; Burg JR; Niemeier RW
Am J Ind Med 1985 Apr; 7(4):323-335
The amount of benzene (71432) absorbed through the skin of hairless- mice was examined and work practices regarding exposure to rubber solvent were observed in a tire building facility. Labeled undiluted benzene and rubber solvent containing 0.5 percent benzene were applied to the skin of male albino hairless-mice. A skin depot containing 100 milligrams (mg) of activated charcoal was affixed to the skin. The depot covered a 0.8 square centimeter area of skin, captured any evaporated test substance, and prevented contamination of urine, feces, and expired breath. A syringe containing 5 microliters of the test substance through the bore of a guide needle touched the skin. Using a solvent flush technique, the test substance was expelled onto the skin. Mice were kept in glass metabolism cages. Skin depots were removed intact and placed into 25 milliliters of toluene for desorption of the labeled benzene from charcoal. Aliquots of the toluene solution were analyzed. Skin application sites were digested by 1 Normal sodium-hydroxide. Expired breath was desorbed and aliquots were analyzed. Feces, aliquots of application site, and carcass digests were oxidized. Urine and cage wash solutions were analyzed by scintillation. Recovery of the applied dose absorbed was 0.89 and 0.88 percent for benzene and rubber solvent, respectively. Total recoveries of radioactive label were greater than 90 percent. No significant differences were observed between treatment groups for any sample category. The relative distributions of absorbed label were similar for both groups. In each case, about 70 percent of the absorbed radioactivity was found in expired breath and excreta. The results from the study and workplace observations together were used to indicate that the workers absorbed 4 to 8mg of benzene per day; 14mg/day is the NIOSH limit. The authors conclude that the experimental model described is useful for directly evaluating the in-vivo dermal absorption of volatile compounds.
NIOSH-Author; Animal-studies; Industrial-chemicals; Organic-chemicals; Skin-absorption; Toxicology; Absorption-rates; Metabolic-study; Excretion; Analytical-methods; Quantitative-analysis; Medical-research
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Journal Article
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American Journal of Industrial Medicine
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division