Seasonal variation in carcinogenic and non-carcinogenic health risks associated with occupational exposure to benzo a pyrene (BaP) among oil refinery workers

Abstract

Benzoapyrene (BaP), as a genotoxic agent, is generated during petroleum refining. Occupational exposure limits (OELs) often fail to protect workers from non-threshold carcinogenic values. Under the ALARA principle, this study evaluated seasonal variations in exposure and health risks of total airborne BaP among refinery workers using deterministic and probabilistic approaches. Personal air sampling (n = 60) was conducted across four high-exposure groups using NIOSH Method 5506 and analyzed via HPLC-FLD. Health risks were estimated using the US EPA framework, incorporating Monte Carlo simulations (10,000 iterations) and Spearman rank sensitivity analysis. The overall mean BaP concentration was significantly higher in summer (0.060 +/- 0.040 mu g /m(3)) than that in winter (0.006 +/- 0.014 mu g /m(3), p < 0.01), remaining below the OEL of 100 mu g /m(3)(for coal tar pitch volatiles). Deterministic Hazard Quotients were well below 1.0 across both seasons (10(-3)-10(-2) in summer and 10(-5)-10(-3) in winter), indicating acceptable non-carcinogenic risks. However, mean summer lifetime cancer risks (LCR) exceeded the 1 & times; 10(-6) as an acceptable benchmark in several groups, ranging from 8.59 & times; 10(-7 )(maintenance) to 2.47 & times; 10(-6) (bitumen plant operators). LCRs in the winter season were lower than those in the summer season. Sampling/laboratory technicians and bitumen plant operators showed the highest exposure, with a 95th percentile LCR of 4.0 & times; 10(-6 )in the summer season. Sensitivity analysis identified BaP concentration (r = 0.81) as the primary risk driver. Despite regulatory compliance, carcinogenic risks exceed the risk-management benchmark during summer.