Hazard vs. exposure: Does it make a difference in identifying chemicals with persistence and mobility concerns?

Area of Science:

• Environmental Chemistry
• Water Quality Assessment
• Chemical Risk Assessment

Background:

• Persistent and mobile (PM) chemicals pose environmental and drinking water threats due to their transport and resistance to removal.
• Current regulations focus on hazard properties (stability, sorption) for identifying PM chemicals, raising concerns about human exposure via drinking water.
• Existing screening criteria may not fully capture the complex factors influencing actual exposure potential.

Purpose of the Study:

• To assess the consistency between hazard-based and exposure-based approaches for identifying PM chemicals.
• To evaluate if chemicals with high persistence and mobility also exhibit high drinking water exposure potential (DWEP).
• To understand the mechanisms driving DWEP in different drinking water sources.

Main Methods:

• A model-based assessment was employed to link hazard properties with DWEP.
• Analysis focused on evaluating whether highly persistent and mobile chemicals consistently correlate with high DWEP.
• Investigated the influence of factors like volatilization and particle-bound transport on DWEP.

Main Results:

• Chemicals with the highest DWEP generally exhibit persistence and mobility, but the converse is not always true.
• Volatilization and advective particle-bound transport significantly impact DWEP, in addition to stability and sorption.
• Hazard metrics are more effective for de-prioritizing chemicals with low exposure potential rather than prioritizing those with high potential.

Conclusions:

• Hazard properties are necessary but not sufficient for predicting high DWEP.
• DWEP is influenced by distinct mechanisms across different water sources: sorption (groundwater), stability (surface water), and both (riverbank filtration).
• Future research should integrate exposure potential into the identification and prioritization of PM chemicals.