Drinking Water Contaminants Kidney Disease Risk
Brominated Disinfection Byproducts Linked to Increased Chronic Kidney Disease Risk
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New Study Highlights Potential Dangers of commonly Used Water Treatment Chemicals
A groundbreaking study published in JAMA Network Open has identified a significant association between exposure to brominated trihalomethanes (THMs), a common byproduct of water disinfection, and an increased risk of chronic kidney disease (CKD). The research suggests that current regulatory limits for total THMs may not be sufficient to protect public health,particularly concerning the long-term effects of specific brominated compounds.
key Findings: Brominated THMs Emerge as Major Contributor to CKD Risk
The study, which tracked a large cohort over time, found a compelling link between residential exposure to THMs and the growth of CKD. The hazard ratio (HR) for CKD associated with THM exposure was 1.43 (95% CI, 1.23-1.66; P < .001), indicating a substantial increase in risk.further analysis using mixture modeling revealed that brominated THMs were the most significant contributor to the observed CKD risk, accounting for 52.9% of the association. Other identified contributors included uranium (35.4%), arsenic (6.2%), and chloroform (5.5%). This finding is particularly noteworthy as brominated THMs are not regulated separately from total THMs, despite emerging evidence of their greater nephrotoxicity.
Biological Plausibility: How Brominated THMs May Harm kidneys
The biological mechanisms underlying this association are supported by prior research. Animal studies have demonstrated that brominated THMs, especially bromodichloromethane, can lead to damage in the proximal tubules of the kidneys and a reduction in glomerular filtration rate (GFR). These compounds also exhibit increased mutagenicity when metabolized by glutathione S-transferase theta 1, an enzyme prevalent in renal tissue. Furthermore, they may interfere with the structural integrity of the glomerular basement membrane by disrupting collagen scaffold assembly.
Exposure Levels and Increased Risk: Even Within Proposed Limits
The study also examined the impact of specific exposure levels. Chronic exposure to bromodichloromethane within California’s proposed public health goal range (5.8-16.3 μg/L) was associated with a 15% higher risk of CKD compared to exposure levels of 0.2 μg/L or less. Exposure exceeding 16.4 μg/L (representing the 95th percentile) was linked to an even more pronounced 32% increase in CKD risk.
Importantly, the total THM exposure in the study population remained well below the current regulatory limit of 80 μg/L. This suggests that while overall compliance with regulations might potentially be met, the specific composition of THMs, particularly the presence of more potent brominated forms, could still pose a significant long-term health threat.
Implications for Public Health and Regulation
The authors of the study emphasize the need for a re-evaluation of water treatment practices and regulatory standards. “Total THM exposure in this study population was well below the regulatory limit (≤ 80 μg/L), suggesting that current policy may not protect against long-term risk,” they stated. “In our study, brominated THMs were associated with the greatest CKD risk and emerged as the largest contributor in our mixture analysis. Brominated THMs are not separately regulated from [total] THM, although prior evidence suggests that they may be more nephrotoxic than chloroform.”
Given the escalating global burden of CKD, the researchers urge regulators and clinicians to consider the potential nephrotoxic risks associated with commonly used water treatment methods.
Study strengths and Limitations
The study’s strengths include its longitudinal design, substantial sample size, and detailed tracking of residential exposures. However, the researchers acknowledge certain limitations, such as the inability to account for individual water consumption habits, home filtration practices, or non-residential exposures. Additionally, CKD diagnoses were based on administrative data, and the cohort did not include specific biomarkers like proteinuria or direct GFR measurements.
Despite these limitations, the findings provide crucial insights into the potential health impacts of disinfection byproducts in drinking water, underscoring the importance of ongoing research and adaptive public health policies.
References:
- Medgyesi DN, Mohan S, Bangia K, et al. Community water trihalomethanes and chronic kidney disease. JAMA Netw Open. 2025; 8 (7): E2