Cytogenetic analysis of an exposed-referent study: perchloroethylene-exposed dry cleaners compared to unexposed laundry workers.

BACKGROUND: Significant numbers of people are exposed to tetrachloroethylene (perchloroethylene, PCE) every year, including workers in the dry cleaning industry. Adverse health effects have been associated with PCE exposure. However, investigations of possible cumulative cytogenetic damage resulting from PCE exposure are lacking. METHODS: Eighteen dry cleaning workers and 18 laundry workers (unexposed controls) provided a peripheral blood sample for cytogenetic analysis by whole chromosome painting. Pre-shift exhaled air on these same participants was collected and analyzed for PCE levels. The laundry workers were matched to the dry cleaners on race, age, and smoking status. The relationships between levels of cytological damage and exposures (including PCE levels in the shop and in workers' blood, packyears, cumulative alcohol consumption, and age) were compared with correlation coefficients and t-tests. Multiple linear regressions considered blood PCE, packyears, alcohol, and age. RESULTS: There were no significant differences between the PCE-exposed dry cleaners and the laundry workers for chromosome translocation frequencies, but PCE levels were significantly correlated with percentage of cells with acentric fragments (R2 = 0.488, p < 0.026). CONCLUSIONS: There does not appear to be a strong effect in these dry cleaning workers of PCE exposure on persistent chromosome damage as measured by translocations. However, the correlation between frequencies of acentric fragments and PCE exposure level suggests that recent exposures to PCE may induce transient genetic damage. More heavily exposed participants and a larger sample size will be needed to determine whether PCE exposure induces significant levels of persistent chromosome damage.

Adaptive response induction and variation in human lymphoblastoid cell lines.

Adaptive response is a term used to describe the ability of a low, priming dose of ionizing radiation to modify the effects of a subsequent higher, challenge dose, but it has been observed to be highly variable in both presence and magnitude. To examine this variability, 10 human lymphoblastoid cell lines were screened for adaptability to 137Cs radiation by determining the frequency of micronuclei in binucleated cells. Of these, six adapted, three did not adapt and one was synergistic. The assay was then repeated on each of the cell lines to test for reproducibility. Five cell lines showed the same result both times; four of these adapted and one did not. To determine whether fluctuations in the cell cycle distribution in the irradiated population of cells could alter the adaptive response, and therefore explain some of the observed variability, two of the cell lines were tested for adaptation after enriching the population, by synchronization, for a given cell cycle stage. In both cell lines, the direction of the response was altered when the distribution of cells within the cell cycle was changed, suggesting that the adaptive response can be affected by cell cycle stage at the time of irradiation.