The relationship between urine polycyclic aromatic hydrocarbons and depressive symptoms in American adults

Studies have shown that Polycyclic aromatic hydrocarbons (PAHs) were neurotoxic, and PAHs exposure may be related to depressive symptoms. Thus, we conducted this study for further explorations.

Data from the National Health and Nutrition Examination Survey (NHANES) database of the 2005-2014 cycles were used. The independent variables were urine PAHs metabolites, including 1-hydroxynaphthalene (1-NAP), 2-hydroxynaphthalene (2-NAP), 3-hydroxyfluorene (3-FLU), 2-hydroxyfluorene (2-FLU), 1-hydroxyphenanthrene (1-PHE), and 1-hydroxypyrene (1-PYR). The dependent variable was depressive symptoms according to the Patient Health Questionnaire (PHQ)-9. Multivariate logistic regression analyses and the restricted cubic splines were used in the analyses.

A total of 7647 adults aged 20 or above were included in the analyses. In the Crude model and Model 1 (adjusted for age and gender), compared with quartile (Q) 1, the risk of depressive symptoms increased in Q4 for all the six PAHs metabolites. However, in Model 2, after adjusted for more covariates, the results were no more significant. In the stratified analysis by gender, in Model 2, the weighted OR (95% CIs) of depressive symptoms were 2.78(1.04,7.38), 3.17(1.23,8.18) for 1-NAP, 2-NAP in Q4 for females, respectively. Besides, a non-linear dose-response relationship was found between 1-NAP, 2-NAP, and depressive symptoms in females, too.

Cross-sectional study could not infer causality.

Our study found a positive association between urine PAHs and depressive symptoms in females, and more studies are needed to explore the relationships between PAHs exposure and depressive symptoms in the general adult populations.