Risk assessment of manufacturing equipment surfaces contaminated with DDTs and dicofol

Decommissioning of manufacturing plant in the chemical industry includes inspection of the surfaces of production equipment for potential contamination and associated health risks. In the present study wipe-samples were taken from the surfaces of dicofol manufacturing equipment at a chemical factory in north China and analyzed for chemicals of concern (COCs). Occupational hygiene assessment was conducted to assess the risks to demolition workers and health risk assessment was performed to evaluate the risks to demolition and general industrial workers. The concentrations of COCs on the equipment surfaces were found to be 0.54-3.75 × 104 mg DDTs m− 2 and 0.15-4.38 × 103 mg dicofol m− 2. The average concentration of p,p′-DDT does not represent an unacceptable risk to the demolition workers using occupational hygiene assessment. Under the industrial scenario the carcinogenic risks of COCs ranged from 2.28 × 10− 7 to 1.79 × 10− 2 for p,p′-DDT, 6.18 × 10− 7 to 3.04 × 10− 3 for p,p′-DDD and 1.89 × 10− 6 to 0.16 for p,p′-DDE. The non-carcinogenic hazard indices ranged from 3.86 × 10− 3 to 3.03 × 102 for p,p′-DDT and 1.16 × 10− 3 to 33.94 for dicofol. Both carcinogenic risk and hazard index of COCs under the industrial scenario were higher than under the demolition scenario. Oral ingestion and dermal contact were the major pathways and accounted for > 88% of the total exposure of COCs. Parameter sensitivity analysis shows that equipment surface concentration (Cs), frequency of contact with surface (EV), fraction of dust transferred from surface to skin (FTss) and exposure frequency (EF) were the most sensitive parameters and these should be acquired on a site-specific basis. The accuracy of the risk assessment was controlled largely by the variation in the sensitive parameters and the uncertainty of the exposure model for the inhalation pathway.