Abstract A05: Cumulative risk, key characteristics of carcinogens, and hallmarks of cancer analysis for carcinogenic drinking water contaminants
Level 5 - mechanism / opinion, no new human data
Risk assessment modeling based on exposure occurrence data rather than direct human clinical or epidemiological observation (design analogy).
OpenAlex W3041932074 · doi:10.1158/1940-6215.envcaprev19-a05
What was done
The authors conducted a cumulative cancer risk assessment modeling exposure to 22 carcinogenic contaminants using drinking water occurrence data from 2010 to 2017 across United States community water systems. They combined risk-based cancer calculations with mode-of-action evaluations using the Hallmarks of Cancer and Key Characteristics of Carcinogens frameworks to estimate population-level lifetime cancer burdens.
What was found
An estimated 269,957,711 people served by 43,142 community water systems were exposed to mixtures of carcinogenic contaminants above de minimis risk levels. The model estimated that 98,657 lifetime cancer cases could be attributable to contaminated tap water, with arsenic accounting for nearly half of the cases, followed by disinfection byproducts, radiological contaminants, and hexavalent chromium. Approximately one-third of expected cases occurred in systems serving 10,000–100,000 people, one-third in systems serving 100,000–1,000,000 people, and less than one-fifth in systems serving under 10,000 people, though the smallest systems carried the highest individual-level risks.
Why it matters
Standard toxicological evaluations usually evaluate single agents in isolation, potentially overlooking cumulative harms from co-occurring chemicals. This study provides a national-scale model estimating how multi-contaminant drinking water exposures contribute to cancer incidence.
Limits
This is a conference abstract describing a theoretical risk assessment model, not an epidemiological study directly measuring human cancer incidence. Estimates rely on standard risk extrapolation models and exposure assumptions that do not measure actual individual water consumption, household filtration use, or biological interactions among chemical mixtures.
Cited by
- supports The Environmental Working Group reported that over 122 million Americans drink tap water with high levels of cancer-causing chemicals.
- supports The Environmental Working Group demonstrated that over 122 million Americans drink tap water containing elevated levels of carcinogenic chemicals.