The urinary level of 2,4,5-trichlorophenol was positively associated with both all-cause and cause-specific mortalities in general adult residents of United States

Abstract

Chlorophenols are widespread environmental organic pollutants with harmful effects on human beings. Although relationships between chlorophenols and various dysfunctions/diseases have been reported, the contribution of chlorophenols exposure to mortalities is underdetermined. In this cohort study, we included 4 types of urinary chlorophenols, aiming to estimate associations of chlorophenols exposure with all-cause and cause-specific mortalities. Urinary chlorophenols were examined at baseline of National Health and Nutrition Examination Survey (NHANES) 2003–2010, and adjusted for the urinary creatinine level. Associations between chlorophenols and mortalities were estimated using COX regression analyses, results were shown as hazard ratio (HR) and 95% confidence interval (95% CI). By dividing participants into four subgroups based on quartiles of urinary levels of chlorophenols, associations between mortalities and categorical variables of chlorophenols were estimated. Furthermore, the quantile g-computation analysis was used to estimate the joint effects of 4 chlorophenols on mortalities. Among 5817 adults (2863 men), 1034 were deceased during the follow-up. After adjusted for confounders, 2,4,5-trichlorophenol (2,4,5-TCP) was found to be positively associated with both all-cause (HR = 1.46; 95% CI: 1.16, 1.84) and cardiovascular disease (CVD) mortalities (HR = 1.60; 95% CI: 1.00, 2.55). Compared to the subgroup of the lowest level of chlorophenols, participants in subgroups of higher 2,4,5-TCP levels showed higher risk of all-cause mortality (P-value for trend = 0.003). For CVD mortality, HRs in subgroups of higher levels of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) were statistically significant (P-values for trend were 0.017 for 2,4-DCP and 0.049 for 2,4,6-TCP). The HRs (95% CI) of joint effects of 4 chlorophenols were 1.11 (1.01, 1.21) and 1.32 (1.10, 1.57) for all-cause and CVD-specific mortalities, and 2,4,5-TCP showed the highest weight in joint effects. All of these findings implied that among 4 urinary chlorophenols we included, 2,4,5-TCP might be a sensitive one in associations with mortalities among general populations.