MEASUREMENT OF FREQUENCIES OF HPRT MUTANTS, CHROMOSOMAL-ABERRATIONS, MICRONUCLEI, SISTER-CHROMATID EXCHANGES AND CELLS WITH HIGH-FREQUENCIES OF SCES IN STYRENE DICHLOROMETHANE-EXPOSED WORKERS/

Frequencies of HPRT mutants (MFs), chromosomal aberrations with or wit hout gaps (CA +; CA -), aberrant cells (AC), micronuclei (MN), sister- chromatid exchanges (SCEs) and cells with high frequencies of SCEs (HF Cs) were measured in lymphocytes collected from 46 workers occupationa lly exposed to styrene and dichloromethane (DCM = methylene chloride). These parameters were also determined in 23 controls. Time-weighted a verage (TWA) values for styrene and DCM exposure during an 8-h working day were respectively 70 mg/m(3) (range: 0-598) and 108 mg/m(3) (rang e: 0-742). These values correspond to TWA values of 17 ppm styrene and 31 ppm DCM. In exposed workers, ah cytogenetic parameters were signif icantly enhanced (P < 0.0001; one-sided), but, due to the lack of appr opriate control data, no definite conclusions could be drawn concernin g the mutagenicity of styrene/DCM exposure. Duration of exposure was n ot correlated with genetic effects analyzed. The TWA value for styrene was not correlated with the extent of genetic damage detected, but th e TWA value for DCM was positively correlated with the frequencies of chromosome aberrations (with gaps) and aberrant cells. These observati ons make it difficult to decide whether styrene or DCM, or both chemic als, induced the cytogenetic effects observed in exposed workers. Usin g the present styrene/DCM data, earlier ethylene oxide data and unpubl ished epichlorohydrin data, the relative sensitivity of the genetic en dpoints to detect genotoxic exposure was: HFC > CA - > CA + > SCE > MN > HPRT.