Environmental and personal BTEX exposure and inhalation health risks in healthcare-waste treatment units

Abstract

This study investigated spatial and operational variations in airborne benzene, toluene, ethylbenzene, and xylenes (BTEX), personal exposure, and inhalation health risks in eight healthcare-waste treatment units in Hamadan, Iran. A total of 64 area air samples were collected, with 16 samples for each location–condition combination (indoor inactive, indoor post-treatment, perimeter inactive, and perimeter post-treatment), and personal breathing-zone samples were obtained from 16 workers. BTEX was analyzed by gas chromatography, and health risks were estimated using the U.S. Environmental Protection Agency framework. Risk estimates were based on 4 h/day of exposure, 300 exposure days/year, and the selected toxicity values. Monte Carlo simulation with 10,000 iterations characterized risk variability and sensitivity. Mean total BTEX increased significantly from 178.50 ± 15.56 to 307.57 ± 19.45 µg/m 3 indoors and from 34.54 ± 3.18 to 64.22 ± 6.69 µg/m 3 at perimeter locations. Post-treatment concentrations were positively associated with temperature and the number of autoclave cycles and inversely associated with time since the last cycle and relative humidity (RH). Post meridiem (PM)-shift workers had higher total BTEX exposure, hazard index (HI), and daily inhalation dose than ante meridiem (AM)-shift workers. Aggregate HI remained < 1 in observed and simulated estimates under the specified exposure assumptions. In contrast, benzene and cumulative carcinogenic risks exceeded 1 × 10 –6 but remained below 1 × 10 –4 . Exposure time was the dominant contributor to non-carcinogenic risk variability. These findings support continued occupational monitoring and control of autoclave-related BTEX exposure, particularly during post-treatment activities and prolonged exposure.