Drinking water lifetime health advisories are developed by EPA and intended to provide information on contaminants that can cause human health effects and are known or anticipated to occur in drinking water. EPA has published lifetime health advisories for four PFAS: PFOA at 0.004 parts per trillion (ppt), PFOS at 0.020 ppt, GenX at 10 ppt, and PFBS 2,000 ppt. These lifetime health advisories are developed to indicate the level of these PFAS that can be safely present in drinking water without causing adverse effects to consumers over a lifetime of exposure, including sensitive subpopulations like pregnant mothers, immunocompromised individuals, and children.
EPA develops health advisories by reviewing animal and human health studies to determine the levels of exposure at which individual adverse health effects may occur. EPA will consider strength of the study, how the chemical moves through the body and breaks down, and the applicability of the study to humans. Ultimately, health advisories are reflective of the sensitive health endpoint (i.e., the adverse effect that occurs at the lowest level). For EPA’s recently published lifetime health advisories, the health advisory levels were derived for PFOA and PFOS based on a decreased response in 7-year-old children receiving the tetanus and diphtheria vaccine. The GenX and PFBS health advisory levels were derived based on critical liver effects in mice and observed hypothyroidism in newborn mice, respectively.
Health advisories are structured to indicate the level of the contaminant in drinking water at which the sensitive health effect does not occur and to indicate the broader health effects that may occur at higher levels.