HPRT MUTATION FREQUENCY AMONG WORKERS EXPOSED TO 1,3-BUTADIENE IN CHINA

Hypoxanthine-guanine phosphoribosyl transferase (hprt) mutation freque ncy (M(f)) was studied in workers at a polybutadiene rubber production facility in Yanshan, China. Exposed workers included for study were a ctive either as process analysts, who sampled butadiene production pro cess lines and analyzed product by gas chromatography, or as process o perators, who did routine process control, minor maintenance and, as n eeded, major repair operations. For process analysts at the polymer an d dimethyl formamide (DMF) facilities, the median air levels of ED wer e 1.0 and 3.5 ppm, respectively. Among process operators, air levels o f 1.1 ppm were found during routine activities, while the median air l evel during pump repair and related operations was 45 ppm (6-h time-we ighted average). Overall, M(f) was similar in unexposed (mean M(f) = 2 0.2 x 10(-6)) and butadiene-exposed (mean M(f) = 21.6 x 10(-6)) worker s (P = 0.68). M(f) decreased with cloning efficiency, increased with a ge, and was moderately greater in women than in men. After adjustment by multiple regression analysis for mean age, sex, and cloning efficie ncy, the adjusted mean M(f) (X(adj)) was 13.6 x 10(-6) in unexposed an d 18.0 x 10(-6) in butadiene-exposed. This 32% difference was, however , not statistically significant (P = 0.13). Butadiene exposure was ass ociated with a modest, if any, increase in hprt M(f) in this populatio n of Chinese workers.