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The risk of occupational exposure to mercury vapor in some public dental clinics of Baghdad city, Iraq

Abstract Background: Dental workers are exposed to elevated levels of elemental mercury vapor substantially above the occupational exposure standards when placing or removing mercury/silver tooth restorations and disposing of mercury waste. This results in a significant increase in occupational exposure and risk of mercury intoxication. Methods: To evaluate the occupational exposure of dental workers to amalgam in four dental clinics in Baghdad city, the concentrations of mercury vapor were measured seasonally from February to November 2016. Samples of blood and urine were collected from 30 dental workers (exposed individuals) and five non-occupationally exposed individuals. Biochemical parameters such as cholesterol, liver enzymes (alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase), renal enzymes (urea and creatinine), total protein and reduced glutathione (GSH) were observed. Results: The results indicated that mercury vapor levels varied from 84.7 ± 18.67 to 609.3 ± 238.90 µg/m3 and most concentrations were above the occupational exposure standards. The results of the biochemical parameters showed a significant increase in levels of cholesterol, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and no significant increase in blood urea and creatinine in dental workers in comparison with unexposed persons (control). Although the results showed a significant reduction in the levels of glutathione and total protein, there was no significant decrease in the levels of alkaline phosphatase (ALP) in exposed dental workers when compared with non-occupationally exposed individuals. Conclusions: It is concluded that mercury vapor concentrations in the indoor air of some dental clinics in Baghdad city are high and exceed the OSHA STEL(Occupational Safety and Health Administration Short Term Exposure Limit). The present data showed that altered biochemical parameters can be used as efficient bioindicators for mercury toxicity.