Renal function among naphtha-exposed automotive workers.

Abstract

The association between naphtha exposure and urinary excretion of total protein, albumin, $\beta$-N-acetylglucosaminidase ($\beta$-NAG), and $\beta\sb2$-microglobulin was assessed cross-sectionally and prospectively, over one year, among workers at an automotive plant that used naphtha to calibrate fuel injectors. Participants consisted of 248 workers who provided spot urine samples in June 1988 and 181 workers who provided specimens again in June 1989. The air concentrations of naphtha at the plant ranged from 6 to 790 mg/m$\sp3$ and the length of exposure ranged from 0.8 to 7.3 years. In both 1988 and 1989, the overall distributions of the four measures of renal function appeared consistent with those of an unexposed population. In cross-sectional analyses, there were no statistically significant associations in the expected direction between cumulative or recent naphtha exposure and the measures of renal function. In longitudinal analyses, the change in $\beta$-NAG level was positively associated with the change in recent naphtha exposure (p =.004). The effect of the naphtha exposure during one workweek was assessed among 17 workers who provided urine samples Monday pre-shift, Monday post-shift, and Friday post-shift. No associations were found between the change in the measure of renal function and naphtha exposure in the intervening period.