Exposure assessment of workers to airborne PCDD/Fs, PCBs and PAHs at an electric arc furnace steelmaking plant in the UK.

Occupational exposure studies were undertaken at a UK electric arc furnace (EAF) steelmaking plant to investigate the exposure of workers via inhalation to dioxins, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (B[a]P). Surveys were undertaken in areas including the melting shop, the casting department and a furnace control cabin. The highest concentrations of dioxins and PCBs were found inside the melting shop nearby EAFs, whereas dioxin and PCB concentrations in the casting department and inside the control cabin were significantly lower. Risk characterization was carried out by comparing the daily intake of dioxins and PCBs through inhalation with the recommended tolerable daily intake (TDI). Health risk assessments were also carried out by combining exposure data with inhalation cancer potency factors to quantify the cancer risk. For the most exposed category of workers (melting shop workers), the estimated daily intake via inhalation was 0.35 pg WHO-TEQ kg(-1) body weight (bw) in the worst case scenario. Considering that the average UK adult exposure to dioxins from the diet is 1.8 pg WHO-TEQ kg(-1) bw day(-1), the results indicated that the estimated daily intake of dioxins via inhalation at the EAF would not result in the recommended range of the TDI (1-4 pg WHO-TEQ kg(-1) bw day(-1)) being exceeded. Cancer risks for a 40-year occupational exposure period were determined by multiplying the inhalation dose by the inhalation cancer potency factor for 2,3,7,8-tetrachlorodibenzo-p-dioxin. For melting shop workers, cancer risks from exposure to dioxins and PCBs ranged from 2.05 x 10(-5) to 7.54 x 10(-5). Under most regulatory programmes, excess cancer risks between 1.0 x 10(-4) and 1.0 x 10(-6) indicate an acceptable range of excess cancer risk, suggesting a limited risk from dioxin exposure for workers in the EAF plant. For the calculation of excess cancer risks, no account has been taken of the protection provided by protective respiratory equipment worn by EAF workers. If personal protective equipments were taken into consideration, it is likely that the excess cancer risks for EAF workers would have been lower and considered as negligible. The highest concentrations of PAHs were found in the melting shop and the casting areas of the plant. In the melting shop area, B[a]P concentrations ranged from 1.4 to 24.5 ng m(-3), with a mean value of 7 ng m(-3). No workplace exposure limits have been published by the Health and Safety Executive in the UK for PAHs; however, the B[a]P concentrations found were below the limit value of 150 ng m(-3) (8-h time-weighted average) specified for workplace exposure in France. Exposure assessment of workers to PAHs via inhalation was carried out by calculating a potential cancer risk considering a 40-year occupational exposure period and B[a]Peq concentrations. Estimated cancer risks for the most exposed category of workers (i.e. melting shop workers) ranged from 3.66 x 10(-6) to 1.64 x 10(-5). The cancer risks determined in this study were well within an acceptable range of excess cancer risk of 1.0 x 10(-4) to 1.0 x 10(-6), specified by the US Environmental Protection Agency.