Occupational Exposure to Mercury: Air Exposure Assessment and Biological Monitoring based on Dispersive Ionic Liquid- Liquid Microextraction

Background: Exposure to mercury (Hg) as a heavy metal can cause health effects. The objective of this study was to assess occupational exposure to Hg in a chlor-alkali petrochemical industry in Iran by determining of Hg concentrations in air, blood and urine samples. Methods: The study was performed on 50 exposed subjects and 50 unexposed controls. Air samples were collected in the breathing zone of exposed subjects, using hopcalite sorbents. Analysis was performed using a cold vapor atomic absorption spectrophotometer (CV-AAS) according to NIOSH analytical method 6009. For all participants, blood and urine samples were collected and then transferred into sterile glass tubes. After micro-extraction with ionic liquid and back extraction with nitric acid, Hg concentrations in blood and urine samples were determined by CV-AAS. Results: The mean concentration of air Hg was 0.042± 0.003 mg/m3. The mean concentrations of Hg in blood and urine samples of exposed subjects were significantly higher than unexposed controls (22.41± 12.58 versus 1.19± 0.95 μg/l and 30.61± 10.86 versus 1.99± 1.34 μg/g creatinine, respectively). Correlation of air Hg with blood Hg, urine Hg and blood Hg-urine Hg ratio were significant statistically (P< 0.05). Conclusions: The values of Hg in blood and urine samples of chlor-alkali workers were considerably high. Correlation coefficients showed that blood Hg and blood Hg-urine Hg ratio are better indicators than urine Hg for assessing occupationally exposed workers in terms of current exposure assessment.