Int Arch f)rcn Fnvirnn Tepnlth ( 1 Q 99 Q 6420 Q 9-15 . ~~'1 |_ 11 ~ ~ W 9 Wl J II~VIISI 111 · b "V J / Intemtional Archivesof t U Ipalionalufd Environmental Health © Springer-Verlag 1992 Chromosome aberrations and micronuclei in lymphocytes of workers exposed to low and medium levels of styrene R Tomanin l , C Ballarin, G B Bartolucci l , E De Rosa 2 , G Sessa 3 , G Iannini 4 , A R Cupiraggi 4 , and F Sarto 5 'Institute of Occupational Health, University of Padova, Via Facciolati 71, I-35127 Padova, Italy 2 Chair of Occupational Health, University of Ferrara, Italy 3 Occupational Health Inspectorate (S M P I L ), U L S S 32, Portomaggiore, Ferrara, Italy 4 Occupational Health Inspectorate (S M P I L), U L S S 20, Casalecchio sul Reno, Bologna, Italy 5 Occupational Health Inspectorate (S P I S A L), U L S S 21, Padova, Italy Received November 29, 1991 / Accepted May 8, 1992 Summary In the present study we analysed 19 workers exposed to styrene in two factories where polyester resins were used Because of the different sizes of the pieces undergoing resin processing, the environmental styrene concentrations and urinary mandelic acid (MA) levels of the analysed subjects were quite different in the two plants examined Cytogenetic monitoring was per- formed by analysis of chromosome aberrations (C As) and micronuclei (Mn) in peripheral blood lymphocytes. Cytogenetic analysis revealed a significant increase in the percentage of aberrant cells and total aberrations in the group with higher styrene exposure (group 2) and no increase in the group with lower exposure (group 1), as compared with matched controls Mn frequencies were not significantly increased in the two exposed popula- tions No correlations between length of exposure and CA or Mn frequency were found, and a weak correlation was found between exposure levels, measured as urinary MA, and Mn frequencies Only 5 of the 12 exposed workers examined in group 2 had urinary MA levels higher than the limit recommended by the ACGIH in 1990-91 l 1 l Significant increases in DNA damage are therefore already found at urinary MA levels lower than the internationally suggested exposure limits. Key words: Chromosome aberrations Micronuclei - Peripheral blood lymphocytes Styrene Introduction Cytogenetic monitoring of human exposure to styrene in the work environment has been widely evaluated in past years by using both chromosome aberration (CA) and sister chromatid exchange (SCE) l 2, 4, 8-10, 12, 13, 15-18, 20, 23, 26, 28, 30 l and, more recently, by micro- nucleus (Mn) analysis l 8, 11, 15, 16, 20 l Since 1977, the year in which the first cytogenetic analysis of exposed Correspondence to: R Tomanin workers was published l 17 l, several other studies show- ing contradictory results on the cytogenetic effects of styrene have been reported About 50 % of these have noted a significant increase in the frequency of one or more of the cytogenetic parameters evaluated l 2, 4, 7, 11, 16-18, 30 l In general, although a significant in- crease in damage in the exposed subjects with respect to controls was not necessarily found, the data in the litera- ture reveal a relationship between exposure levels and presence of induced damage, the environmental thresh- old limit of 50 ppm ( 215 mg/m 3 ) still being critical. Human exposure to styrene is usually evaluated by measuring the urinary concentrations of mandelic and phenylglyoxylic acids l 3 l which, however, should only be considered as indicators of very recent exposure l 5 l while cytogenetic endpoints may represent indicators of long-term exposure. With reference to the biological exposure index (BEI) adopted by the ACGIH l 1 l, the urinary mandelic acid (MA) level considered acceptable is 800 mg/g creatinine However, significant increases in the cyto- genetic parameters evaluated in the present work were found in the literature at far lower exposure levels than the established limit A significant increase in C As has already been found at mean urinary MA concentrations of less than 500 mg/g creatinine l 4, 10, 18 l. In the present study, two small groups of workers ex- posed to two different levels of styrene were examined: urinary MA levels and frequencies of C As and Mn in peripheral blood lymphocytes were estimated Mn anal- ysis was performed by the cytochalasin B-block method l 6 l, with modifications. Materials and methods Subjects and work environment The workers analysed in the present study were employed in two factories where polyester resins were used: the first produced small fiberglass tanks and the second, fiberglass boats. For both exposed groups, a control group matched for sex, age and smoking habits was also analysed for CA and Mn frequencies.