Is drinking water with low PFAS a significant source of human exposure? Evidence summary

Area of Science:

• Environmental Health Sciences
• Toxicology
• Public Health

Background:

• Widespread low-level contamination of drinking water with per- and polyfluoroalkyl substances (PFAS).
• Incomplete characterization of the contribution of low-level PFAS in drinking water to human body burdens.

Purpose of the Study:

• To synthesize evidence on the contribution of low-level PFAS (<100 ng/L) in drinking water to human blood PFAS concentrations.
• To investigate the impact of specific PFAS compounds and consumption patterns on body burdens.

Main Methods:

• Systematic literature search of Embase, MEDLINE, and Scopus.
• Inclusion of 10 original human studies (n=4576) reporting both drinking water and blood/serum/plasma PFAS concentrations.
• Focus on low-level water exposures (<100 ng/L).

Main Results:

• Low-range drinking water PFAS concentrations were associated with measurable increases in blood PFAS across multiple countries.
• Perfluorohexanesulfonic acid (PFHxS) showed the most consistent and pronounced relationships.
• High water intake (≥1.8 L/day) and duration of residence amplified associations, particularly in children and high-consuming adults.

Conclusions:

• Even low drinking water PFAS concentrations, especially PFHxS, materially contribute to circulating PFAS in specific subgroups.
• Findings support compound-specific risk assessment and re-evaluation of relative source contribution assumptions for sensitive populations.
• Need for standardized methods and longitudinal designs to refine low-range concentration-response relationships and cumulative exposure estimates.