Association of blood trihalomethane concentrations with hypertension in US adults: A nationwide cross-sectional study

Trihalomethanes (THMs), as the most common species of disinfection byproducts in chlorinated water, have been associated with hypertensive disorders in pregnancy. However, there is sparse epidemiological evidence regarding the possible link between THMs exposure and hypertension in general adults. In the present study, we aimed to characterize the associations between THMs exposure and hypertension in general adults. We performed cross-sectional analyses of 15,135 adults from the 1999-2018 National Health and Nutrition Examination Survey. In the general US adults, the median blood concentrations of the chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (TBM) were: 4.80 pg/mL, 0.71 pg/mL, 0.44 pg/mL and 0.71 pg/mL, respectively. And adults in the highest tertile of blood TBM and DBCM had odds ratios of 1.20 (95 % confidence intervals: 1.02, 1.42) and 1.15 (1.01, 1.30), respectively, for hypertension, compared with adults in the lowest tertile. Also, significant positive associations between blood brominated THM concentrations (sum of TBM, BDCM and DBCM) and prevalent hypertension were observed. In addition, significant interactions with BMI were demonstrated for Br-THMs (P for interaction = 0.017). Our study provides epidemiological evidence supporting a positive association between blood THMs and hypertension by using the nationally representative data, highlighting the need for further investigations to deepen our findings and elucidate the underlying mechanisms.