Where It Comes From
Decaying leaves/soils (natural organic matter), wastewater effluent, stormwater runoff, and some industrial discharges raise UV254 in source waters [1].
How You Are Exposed
You aren’t exposed to UV254 itself; it signals potential exposure to DBPs in tap water from drinking, cooking, and showering (ingestion, inhalation, skin) [2][3].
Why It Matters
High UV254 correlates with aromatic organic carbon and greater DBP formation potential; DBPs like trihalomethanes and haloacetic acids are regulated because long-term exposure can increase cancer risk and cause other health effects [1][2][3].
Who Is at Risk
People on chlorinated surface‑water systems with high organic matter; heavy tap‑water users (e.g., long hot showers); pregnant people and infants may be more sensitive to DBPs [2][3].
How to Lower Your Exposure
Check your Consumer Confidence Report for DBPs/TOC; use certified activated carbon or reverse‑osmosis filters; ventilate and shorten showers; use cold water for drinking; consider alternative water during advisories [2][3].
References
- [1]U.S. EPA. Method 415.3: Determination of TOC and Specific UV Absorbance at 254 nm in Source and Drinking Waters (2009).
- [2]U.S. EPA. Stage 2 Disinfectants and Disinfection Byproducts Rule – Basic Information and Health Effects.
- [3]World Health Organization. Guidelines for Drinking‑water Quality (latest ed.), chapters on natural organic matter and disinfection by‑products.