One could go through a list of the limits of this study but I am not going to do that here. In short, the inference drawn here is a bit premature. This study reminds me of many published in the 1980s and 1990s and written intentionally to alarm. Studies like this can be useful. But a conclusion such as this “Measures should be taken to reduce arsenic in drinking water in order to prevent hypothyroidism” based on the study design applied here is premature.
Gong G, Basom J, Mattevada S, Onger F. Association of hypothyroidism with low-level arsenic exposure in rural West Texas. Environmental Research. 2015 Feb 23;138C:154-160. doi: 10.1016/j.envres.2015.02.001.
It has been reported recently that a higher airborne arsenic level was correlated with higher urinary arsenic concentration and lower serum thyroxin level among urban policemen and rural highway workmen in Italy. The current study was to determine whether exposure to low-level arsenic groundwater (2-22µg/L) is associated with hypothyroidism among 723 participants (118 male and 267 female Hispanics; 108 male and 230 female non-Hispanic whites, NHW) living in rural West Texas counties. Arsenic and iodine levels in their groundwater used for drinking and or cooking were estimated by the inverse distance weighted (IDW) interpolation technique. Groundwater arsenic was ≥8µg/L in 36% of the subjects’ wells while iodine concentration was <1µg/L in 91% of their wells. Logistic regression analysis showed that arsenic in groundwater ≥8µg/L and cumulative arsenic exposure (groundwater arsenic concentration multiplied by the number of years living in the current address) but not groundwater iodine concentration were significant predictors for hypothyroidism among Hispanics (p<0.05) but not NHW after adjusting for covariates such as age, gender, annual household income and health insurance coverage. The ethnic difference may be due to a marginally higher percentage of Hispanics (p=0.0622) who lived in areas with groundwater arsenic ≥8µg/L compared with NHW. The prevalence of hypothyroidism was significantly higher in Hispanics or NHW of this rural cohort than the national prevalence. Measures should be taken to reduce arsenic in drinking water in order to prevent hypothyroidism in rural areas.