Possible synergistic effect of mercury and smoking on sister-chromatid-exchange (SCE) rates in humans

The authors previously reported that exposure to mercury did not appear to cause DNA damage as measured by SCE. They have expanded these studies and have further defined smokers and nonsmokers in the mercury exposed population. Cytogenetic analyses were performed in 29 mercury exposed workers and in 26 controls. The SCE technique was applied to monitor the possible mutagenic effects of elemental and inorganic mercury in somatic cells of exposed workers from two plants that use a mercury electrolytic process to generate caustic soda and copper foil. The mercury levels in blood samples from the exposed workers showed a range of 6.69 to 103.90 ng/ml, with a mean of 26.90 ng/ml. The mercury levels for the controls ranged from 1.52 to 6.08 ng/ml, with a mean of 3.87 ng/ml. Mean duration of exposure was 8 years, with a range of 0.90 to 34.80 years. Results showed a significant increase in the number of SCE in exposed workers with high mercury levels as compared to controls. When exposed workers and controls were subdivided into smokers and nonsmokers, a significant increase in the number of SCE in smoking workers with either low or high mercury levels in their blood were also shown.more » The data suggest a mutagenic effect induced by mercury, which is further enhanced by smoking. Thus, mercury and smoking may exert a synergistic effect in the induction of SCE.« less