Probabilistic health risk assessment of occupational exposure to crystalline silica in an iron foundry in Urmia, Iran.

This study aimed to quantify the exposure of foundry workers to crystalline silica and associated cancer and non-cancer health risks using a probabilistic approach. Breathing zone air samples were collected according to the NIOSH 7602 method and analyzed using Fourier transform infrared spectroscopy. The health risks posed by crystalline silica were then assessed using the EPA-developed inhalation risk assessment model and Monte Carlo simulation. The sensitivity analysis was also conducted to determine the contribution of input parameters to the health risks. The mean concentration of crystalline silica in six foundry stations ranged from 0.029 to 0.064 mg m -3 , exceeding the occupational exposure limits. The average values of cancer risks were greater than the USEPA level, i.e., 1E - 6 in all workstations of the foundry. Workers in sand preparation and molding stations suffered the greatest cancer risks, with the mean value of 2.35E - 5 and 2.10E - 5, respectively. Non-cancer hazard quotient exceeded 1 in all foundry stations ranging from 1.56 (in melting and pouring) to 3.37 (in sand preparation). The 95% upper-bound values of the health risks decreased by 77.52% and 56.77%, assuming the use of engineering controls and wearing respirators by workers, respectively. Sensitivity analyses indicate that concentration was the most sensitive factor contributing to the carcinogenic (46.13%) and non-carcinogenic (67.08%) risks. These findings can aid managers in gaining a better understanding of the silica risks faced by foundry workers and the role of engineering controls and respirators in protecting workers' health.