Contribution of dermal absorption in occupational exposure to organic compounds

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In an occupational exposure to chemical compounds, both dermal absorption and inhalation contribute to invasion of the compounds. For prevention of the exposure, It is important to clarify which route contributes more highly. In the present study, we surveyed in work place where chlorpyrifos (CP), p-tert-butylphenol (PTBP) or 4,4'-methylenebis(2-chloroaniline) (MBOCA) was handled, and their dermal absorption was assessed quantitatively. We also studied on metabolism and urinary excretion of CP and PTBP in animal experiments.1. Urinary excretion rate-of CP and PTBP were studied. Both CP and PTBP were interaperitoneally injected to rats. More than 80% of them administered were excreted into urine within 48 h after the injection.2. There were three surveys in the present study. The first survey was performed for termite control operators who sprayed CP. The urinary metabolite levels were not correlated to CP concentration of air near the operators' breathing zone, but correlated to contact amounts of CP to their upper bodies. Inhalation of CP was almost completely prevented by the wearing of respirators. These results indicate that most of invasion of CP to bodies was accounted by the dermal absorption in this work place. The second survey was carried out in a work place where workers handled PTBP. Amounts of the urinary excretion of PTBP were more than the inhalation amounts estimated from their environmental levels, respiration volume, working time and the amounts of PTBP collected in respirators. This indicates the existence of dermal absorption of PTBP quantitatively. The third survey was done to six workers handling MBOCA. Although MBOCA levels in air near the workers' breathing zone were classified into two degrees, the urinary metabolite levels were divided into three degree. This indicates the existence of dermal absorption of MBOCA qualitatively.