DNA-PROTEIN CROSS-LINKS AND SISTER-CHROMATID EXCHANGE FREQUENCIES IN LYMPHOCYTES AND HYDROXYETHYL MERCAPTURIC ACID IN URINE OF ETHYLENE OXIDE-EXPOSED HOSPITAL WORKERS

The lymphocytes of 25 hospital workers exposed to ethylene oxide and o f a standardized control group were investigated for DNA damage (measu red by alkaline filter elution) and sister chromatid exchange (SCE) fr equencies. Additionally, the excretion of hydroxy ethyl mercapturic ac id (HEMA) in the 24-h urine of ten workers and ten control persons was determined. The peak levels of ethylene oxide in air during the first 8 min after opening of the sterilization unit were measured. Peak lev els of ethylene oxide in the air of up to 417 ppm after opening of the sterilization unit were detected. In the alkaline filter elution assa y we found significantly reduced elution rates in the exposed workers, indicating DNA-protein cross-links. The reduction of the elution rate s through HVLP filters correlated significantly with the exposure clas sification (low, medium, high) (r = -0.45, P < 0.05) and the ethylene oxide peak level after opening of the sterilization unit (r = -0.42, P < 0.05). The SCE frequencies in the standardized control group were s ignificantly elevated. With respect to (n = 78) historic control SCE v alues of our institute, the SCE values of the disinfectors were not si gnificantly elevated (6.54 vs 6.27). The ethylene oxide-exposed worker s did not have a greater percentage of high-frequency SCE cells. The m ean HEMA concentration in the urine of the exposed workers was signifi cantly elevated, but there were wide variations in HEMA concentrations and no correlation to ethylene oxide exposure. We conclude that the a lkaline filter elution assay may be a sensitive parameter for monitori ng the genotoxic damage in lymphocytes of ethylene oxide-exposed worke rs. Determination of the HEMA concentration in urine may be suitable f or the differentiation between ethylene oxide-exposed and nonexposed g roups, but not for individual biomonitoring. The result of the SCE det ermination indicates that the standardization of control groups with r espect to sex, age, and smoking habit seems unsatisfactory. Therefore, it is recommended that in further studies control groups be construct ed with respect to additional lifestyle factors. Additionally, enzyme polymorphisms - especially of glutathione transferase in the case of e thylene oxide exposure - should be taken into consideration and contro lled.