ELSEVIER Mutation Research 312 (1994) 187-191 EnvironmentalMutagenesis No significant increase in sister-chromatid exchanges in cultured blood lymphocytes from workers in a large oil refinery Ahmad M. Khalil a,,, W. Qassem b, Osama M. Kamal c a Department of Biological Sciences, Yarmouk University, Irbid, Jordan, b Hi]jawi College .for Applied Engineering, Yarmouk University, Irbid, Jordan, c Jordan Petroleum Refinery Company, Health Department, Zarka, Jordan (Received 29 September 1993; revision received 24 November 1993; accepted 7 December 1993) Abstract In order to assess the potential genotoxic effects of occupational exposure to petrochemicals, the incidence of sister-chromatid exchanges (SCE) in cultured lymphocytes was studied. Blood samples were taken from 233 individuals (184 exposed and 49 worksite controls) in an oil refinery and from 47 community control persons. The data showed a non-significant elevation of SCE frequency in occupationally exposed workers when compared to non-exposed individuals. The mean SCE frequency per cell ranged from 7.55 + 0.55 in blood of lube oil blending and canning (LOBC) workers to 9.13 + 0.71 in catalytic cracking and water treatment (CCWT) workers. The control values were 6.2 + 0.67 and 7.21 + 0.45 in the community and worksite individuals, respectively. Furthermore, the SCE frequencies were influenced neither by age nor by smoking. Key words: Cultured human lymphocytes; Sister-chromatid exchanges; Occupational exposure; Oil refining I. Introduction Petroleum and petrochemical products are considered major environmental pollutants. They contain a complicated mixture of various chemi- cals that cause mutations and cancers. Olin et al. (1987) reported an elevated risk of brain tumor in people living near a petrochemical plant. It has been indicated that occupational exposure in petrochemical industries is an important factor associated with bladder cancer in males (Bravo et * Corresponding author. al., 1987). Significant elevations in mortality from skin and digestive system cancers among workers exposed to refinery processes were found (Nelson et al., 1987). In a retrospective study, Austin et al. (1986) found an excess of leukemia deaths at an oil refinery. More recently, Schnatter et al. (1992) found a significant excess of malignant melanomas and multiple myelomas among refinery employ- ees. Several investigators have examined the possi- bility that occupational exposure of workers han- dling petroleum and its products has mutagenic consequences. One of these studies (Carrano et al., 1980) showed that lymphocytes of workers handling these products exhibit significantly more 0165-1161/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved SSD! 0165-1161(93)E0061-E