New Approaches to Regulating Disinfection Byproduct Exposures

Area of Science:

• Environmental Chemistry
• Toxicology
• Public Health

Background:

• Current regulations for disinfection byproducts (DBPs) focus on individual chemicals, neglecting the complex mixtures consumers are exposed to.
• This approach is inadequate given the thousands of identified DBPs and the rapid discovery of new ones.

Purpose of the Study:

• To discuss alternative strategies for mitigating exposure to disinfection byproducts (DBPs) beyond the current chemical-by-chemical approach.
• To highlight methods that account for DBP mixtures and uncharacterized compounds.

Main Methods:

• Calculated Additive Toxicity (CAT): Measures DBP exposure by summing concentrations weighted by toxic potency, incorporating in vitro data.
• Bioassays: Assess the combined effects of DBP mixtures, including uncharacterized DBPs, without assuming additivity.
• Multiple Barrier Approach: Combines precursor removal with indicator DBP limits representing broader DBP classes.

Main Results:

• The chemical-by-chemical focus of current regulations is insufficient for managing DBP risks.
• Alternative methods like CAT and bioassays offer more comprehensive risk assessment for DBP mixtures.
• The Multiple Barrier Approach provides a framework for managing DBP formation associated with specific disinfectants.

Conclusions:

• A combination of Calculated Additive Toxicity, bioassays, and the Multiple Barrier Approach can efficiently mitigate public exposure to disinfection byproducts.
• Integrating these strategies offers a more robust and adaptive framework for water quality management and public health protection.