Objective To investigate the relationship between the metabolites of polycyclic aromatic hydrocarbons (PAHs) in urine and the changes in cognitive function of steel mill workers.

Methods In 2019, 960 workers from a coking plant in Shanxi province were selected to undergo basic information investigations, cognitive function tests, and detection for hydroxylated metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) in urine. During the follow-up in 2023, a total of 567 workers completed the cognitive function tests. The Beijing version of the Montreal Cognitive Assessment (MoCA) was employed to test the cognitive function of the workers. High performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) was utilized to detect OH-PAHs in urine. The generalized linear model and the generalized estimation equation were adopted to analyze the relationship between urinary OH-PAHs and the cognitive function of the workers.

Results Subjects were 49 (46, 53) years old at baseline, with 91.7% being the male. In the longitudinal study, the high exposure groups of 2-hydroxynaphthalene (2-OHNAP) and 1-hydroxypyrene (1-OHPYR) showed decreases in attention (β = –0.338, 95%CI: –0.454 to –0.222, P < 0.001; β = –0.450, 95%CI: –0.557 to –0.343, P < 0.001), abstract thinking (β = –0.463, 95%CI: –0.549 to –0.377, P < 0.001; β = –0.360, 95%CI: –0.450 to –0.269, P < 0.001) and the total score (β = –0.863, 95%CI: –1.284 to –0.443, P < 0.001; β = –0.548, 95%CI: –0.987 to –0.108, P = 0.015).

Conclusions Long-term exposure to high concentrations of PAHs can lead to reduced cognitive function in steel mill workers.