Urinary hydroxydiphenyl excretion of workers occupationally exposed to a mixture of diphenyl and diphenylether (Dowtherm A).

A study was carried out in a nylon producing plant to determine exposure to Dowtherm A from frequently occurring leaks in the heating system. The daily exposure to both diphenyl and diphenylether of 20 workers was determined over seven consecutive days. Urine samples before and after the daily eight-hour workshift were obtained and analysed spectrofluorimetrically on hydroxydiphenyl. Urine concentration of creatinin was used as a correction factor for dilution. No correlation was found between the increase of urinary hydroxydiphenyl during the workshift and the eight-hour average exposure to diphenyl for the individual workers. This could be explained by the small variance of the daily exposure of each worker. Averaging, however, for each worker both exposure values and increases of urinary hydroxydiphenyl over 7 d, resulted in an explained variance of 72.5% using regression techniques. No influence of smoking was found.