Heavy metals and prevalence of sexually transmitted infections: a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) 2003–2016

Background: Heavy metals can impact immune system function by increasing susceptibility and progression of infections. Few studies have considered if heavy metals are associated with sexually transmitted infections (STIs). Our aim was to examine the relationship between heavy metals measured in urine and STIs. Methods: We conducted a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES). We examined Chlamydia trachomatis and high-risk human papillomavirus (HPV) genotypes, two of the most common STIs. Nine heavy metals measured in urine were included in the analyses. Poisson regression with robust error variance was used to determine the prevalence ratio (PR) and 95% confidence intervals (95% CI) for the association between the heavy metals and STIs. All models adjusted for age, smoking, race and ethnicity, sex, and the poverty-index ratio. Results: Urinary levels of uranium (PR 1.20, 95% CI 1.05–1.36) and antimony (PR 1.20, 95% CI 1.01–1.44) were associated with chlamydia. Urine barium (PR 1.17, 95% CI 1.06–1.29) was associated with HPV 16/18 genotypes. Similar patterns were observed for urine antimony, cadmium, cesium, lead, mercury, tungsten, and uranium. When stratified by sex, these associations were only observed among female participants. Conclusions: Our findings indicate that heavy metal exposure was associated with STIs. Because this was a cross-sectional study, we cannot determine temporality, and additional research is needed.