PFAS: Navigating the New Drinking Water Health Advisories

EPA defines a HA as a non-enforceable and non-regulatory value which provides technical information to states agencies and other public health officials on health effects, analytical methods, and treatment technologies associated with drinking water contamination. The HA is the minimum concentration of a compound which may present health risks to an individual over a lifetime of exposure. Because there is uncertainty of the health effects associated with long-term exposure to compounds, EPA can set very low HA values.

In contrast, a maximum contaminant level (MCL) is a regulatorily enforceable standard. The EPA has stated its intent to establish a National Primary Drinking Water Regulation for PFOA and PFOS in its Strategic Roadmap. The agency recently reiterated its intent to propose a draft MCL before the end of 2022.

The HA is often the starting point for establishing a new MCL. First, the EPA must identify an MCL goal (MCLG). An MCLG can be a very low target value or even zero. It is important to remember that a goal of zero is just that, a goal. In reality, achieving zero is a target that cannot be measured or practically implemented. Thus, MCLs can be higher factoring in economics and/or can be a technology-based regulation.