Dermal and systemic toxicity after application of semisynthetic metal-working fluids in B6C3F1 mice

About 10 million industrial workers of both sexes are exposed to metal-working fluids (MWFs) via inhalation, skin or both. Our preliminary results, following dermal application of 200 microl of 50% unused (neat) semisynthetic MWF (pH 7 or pH 9.7) to the unshaved backs of 6-wk-old B6C3F1 mice, twice a week for 6 wk, produced significant increase in weights of the liver of both sexes. The purpose of the present study was to determine if this weight change was related to oxidative stress subsequent to MWF exposure and also to determine whether ethanol intake influences this effect. Therefore, 6-mo-old mice of both sexes were exposed to MWFs following the protocol just described, except that the topical application was with 5% MWFs (pH 7 and 9.7, 5 d/wk) with or without adding 5% ethanol to their drinking water (7 d/wk) for 13 wk. The skin histamine levels and mast-cell numbers were significantly increased in the female group treated with 55% MWF (pH 7). The ascorbic acid levels in the liver (both sexes) (all groups except 5%, MWF pH 9.7 males) and testes were reduced significantly. Malondialdehyde levels in the male liver were significantly increased with topical MWF exposure. Glutathione levels were reduced significantly in both male and female liver after 5% MWF (pH 7). Alcohol dehydrogenase activity of the male liver increased significantly after MWF (pH 7). These results suggest that MWFs are absorbed through the skin and produce toxicity in the liver of both sexes and in the male gonads. This may represent an important health risk to MWF-exposed industrial workers, and ethanol may exacerbate this risk.