Tag Archives: trihalomethanes (THMs)

Taiwan study found no association between THMs and kidney cancer

The Odds Ratio reported in this study is not significant, regardless of the interaction of hardness. If hardness did play a role, would it be calcium, or magnesium, or both? An interesting hypothesis, but just conjecture….

Liao, YH, Chen, CC, Chang, CC, Peng, CY, Chiu, HF, Wu, TN, and CY Yang. Trihalomethanes in drinking water and the risk of death from kidney cancer: does hardness in drinking water matter? J Toxicol Environ Health A. 2012 Mar 15;75(6):340-50.

Abstract: The objectives of this study were to (1) examine the relationship between total trihalomethanes (TTHM) levels in public water supplies and risk of development of kidney cancer and (2) determine whether hardness levels in drinking water modify the effects of TTHM on risk of kidney cancer induction. A matched case-control study was used to investigate the relationship between the risk of death attributed to kidney cancer and exposure to TTHM in drinking water in 53 municipalities in Taiwan. All kidney cancer deaths in the 53 municipalities from 1998 through 2007 were obtained. Controls were deaths from other causes and were pair-matched to the cancer cases by gender, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each cancer case. Data on TTHM levels and levels of hardness in drinking water were also collected. The municipality of residence for cancer cases and controls was presumed to be the source of the subject’s TTHM and hardness exposure via drinking water. Relative to individuals whose TTHM exposure level was <4.9 ppb, the adjusted OR (95% CI) for kidney cancer was 0.98 (0.77-1.25) for individuals who resided in municipalities served by drinking water with a TTHM exposure ≥4.9 ppb. However, evidence of an interaction was noted between the use of soft water and drinking water TTHM concentrations. Increased knowledge of the interaction between hardness and TTHM levels in reducing risk of kidney cancer development will aid in public policy decision and establishing standards to prevent disease occurrence.

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Summerhayes et al. 2012: Exposure to Trihalomethanes in Drinking Water and Small-for-gestational age Births

The abstract below appears to exagerate the findings of this study…..a Relative Risk (RR) of 1.06 does not even rise to the level of being called a “weak” association…..

Summerhayes, R.J., G.G. Morgan, H.P. Edwards, D. Lincoln, A. Earnest, B. Rahman, and J.R. Beard. 2012. Exposure to Trihalomethanes in Drinking Water and Small-for-gestational-age Births. Epidemiology. 2012 Jan;(1):15-22.

BACKGROUND: Trihalomethanes in drinking water have been associated with higher occurrence of small-for-gestational-age (SGA) births, although results have been inconsistent.

METHOD: We geocoded residential address for mother of live, singleton, term births to 33 water distribution systems in a large metropolitan area of New South Wales, Australia (314,982 births between 1998 and 2004) and classified births into <10th percentile and ≥10 percentile of weight for gestational age. Mean trihalomethane exposure was estimated by trimester and for the entire pregnancy based on monthly sampling in each of the 33 water distribution systems. We estimated the relative risk (RR) of SGA for exposure to trihalomethanes using log-binomial regression adjusting for confounding.

RESULTS: SGA births increased with mother’s third-trimester exposure to chloroform (RR=1.04 [95% confidence interval=1.02-1.06], across an interquartile range [IQR]=25 μg/L) and bromodichloromethane (1.02 [1.01-1.04], 5 μg/L). Larger associations were found for SGA less than third percentile. Smoking modified the effects of trihalomethane exposure, with generally larger associations in births to nonsmoking mother and weaker or protective associations in births to smoking mothers.

CONCLUSIONS: Mothers’ exposures during pregnancy to total trihalomethane as well as to chloroform and bromodichloromethane were associated with SGA. These associations were modified by maternal smoking during pregnancy.

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