Assessing PAH exposure during construction work of railroad switches using creosote-impregnated ties.

Abstract

The toxicological effects of creosote are primarily attributed to exposure to polycyclic aromatic hydrocarbons (PAHs) and related compounds. This study aimed to assess worker exposure by measuring PAHs in the breathing zone using full-shift air samples, urinary concentrations of 1-hydroxypyrene (1-HP), and dermal exposure through a tape stripping technique. Air sampling was conducted during a work shift on Day 4 (Thursday) of the work week, while urine and dermal samples were collected both before and after the shift on the same day. Additional urine samples were collected at the beginning of the week. Measured concentrations of the 16 priority PAHs identified by the US EPA ranged from 120,000 to 280,000 ng/m3 in the breathing zones of workers handling creosote-impregnated ties. Pyrene concentrations on skin surfaces varied from 0.31 to 140 ng/cm2, with the highest concentrations found on palms and calves. Urinary concentrations of 1-HP increased over the course of the week, ranging from 1.9 to 17 µmol/mol creatinine, indicating substantial variation in individual exposure levels. Workers constructing railroad switches with creosote-treated ties showed elevated urinary 1-HP concentrations during the work week, with most exceeding the British biological monitoring guidance value by Day 4. Dermal uptake was identified as the dominant exposure route using a physiologically based toxicokinetic model. Furthermore, pyrene was detected on skin areas covered by protective clothing, indicating that PAHs can penetrate fabric and that secondary exposure from contaminated work clothes is likely. These findings underscore the need for improved preventive measures to reduce dermal exposure.