# Polycyclic aromatic hydrocarbons exposure as a potential risk factor for miscarriage among women in the United States: A secondary dataset analysis of NHANES data for the period 2005–2014

## TL;DR

This study finds that exposure to certain polycyclic aromatic hydrocarbons, especially from tobacco, is linked to a higher risk of miscarriage in U.S. women.

## Contribution

The study identifies specific PAH metabolites and their nonlinear associations with miscarriage using NHANES data.

## Key findings

- Higher concentrations of specific PAH metabolites are associated with increased miscarriage risk (p<0.05, OR>1).
- A nonlinear relationship exists between 1-hydroxynaphthalene and miscarriage, with a cutoff at 4705 ng/L.
- Subgroup analysis confirmed the robustness of the PAH-miscarriage associations.

## Abstract

Numerous studies have shown that polycyclic aromatic hydrocarbons (PAHs) are endocrine disruptors associated with reproduction, with tobacco smoke identified as a major non-occupational source of PAH exposure. However, there is still a lack of information on the relationship between PAH exposure – particularly from tobacco-related sources – and miscarriage.

The data for this study were obtained from the National Health and Nutrition Examination Survey (NHANES) 2005–2014. Excluding populations with missing PAH, miscarriage, or baseline information, a total of 2573 individuals were included in this study. Logistic regression, linear regression, restricted cubic spline (RCS) analysis and subgroup analysis were used to analyze the effects of PAHs.

Following logistic and linear regression analyses, we found that higher concentrations of 2-hydroxynaphthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 1-hydroxypyrene were associated with miscarriage (p<0.05, OR>1). Moreover, after RCS, we found a nonlinear relationship between 1-hydroxynaphthalene and miscarriage (p=0.01). The relationship between 1-hydroxynaphthalene and miscarriage could be described as an ‘n-shaped’ curve, with a cutoff value (4705 ng/L). At concentrations lower than the cutoff, there was a positive correlation between 1-hydroxynaphthalene and miscarriage. Conversely, at concentrations higher than the cutoff, there was a negative correlation between the two variables. Finally, a subgroup analysis was performed to explore the interaction effect of confounders with the outcome variables, to further demonstrate the robustness of the results.

The probability of miscarriage increases with increasing concentration of certain PAHs in the body. Enhancing monitoring of tobacco-related PAHs exposure is highly important for the prevention of miscarriage.