Urinary polycyclic aromatic hydrocarbon metabolites, plasma p-tau231 and mild cognitive impairment in coke oven workers

Background: As a group of environmental pollutants, polycyclic aromatic hydrocarbons (PAHs) may be neuro-toxic,especially in high-exposure occupational populations. However, the effect of PAHs on mild cognitive impairment (MCI) is still unclear.Objective: We aimed to investigate the relationship between PAH metabolites and MCI and to explore whether plasma p-tau231 can be used as a potential biomarker to reflect MCI in coke oven workers. Method: A total of 330 workers were recruited from a coke oven plant as the exposure group, and 234 workers were recruited from a water treatment plant as the control group. The concentrations of eleven PAH metabolites and plasma p-tau231 were determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) and ELISA. Cognitive function was measured by the Montreal Cognitive Assessment (MoCA) questionnaire. A multivariate logistic regression model and multiple linear regression model were used to analyze the associations of urinary PAH metabolites with the detection rate of MCI, MoCA scores and plasma p-tau231. The dose-response relationships were evaluated using restricted cubic spline models.Results: We found 146 MCI-positive workers in coke oven plant (44.24%), and 69 MCI-positive workers in water treatment plant (29.49%). In addition, the urinary sum of PAH metabolites (E-OH PAHs) was significantly associated with MCI (OR, 1.371; 95% CI:1.102-1.705). Each one-unit increase in ln-transformed E-OH PAHs was associated with a 0.429 decrease in the sum of MoCA, a 0.281 reduction in the visuospatial/executive function and a 9.416 increase in the level of plasma P-Tau231. We found a negative association between plasma P-Tau231 and visuospatial/executive function (beta =-0.007, 95% CI:-0.011,-0.003).Conclusion: Our data indicated that urinary Ʃ-OH PAHs levels of workers were positively associated with MCI and the level of plasma P-Tau231.

Automated summary

This study investigated the relationship between polycyclic aromatic hydrocarbon (PAH) metabolites and mild cognitive impairment (MCI) in coke oven workers, and explored whether plasma p-tau231 can be used as a potential biomarker for MCI. The results showed that the urinary levels of PAH metabolites were positively associated with MCI and plasma p-tau231 levels in coke oven workers.