EPA to Set New MCLs for PFOA and PFOS

During his keynote speech at the PFAS National Leadership Summit on May 22, 2018, EPA Administrator Scott Pruitt  announced EPA's plan to set maximum contaminant levels (MCLs) for two toxic PFAS chemicals, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) under the Safe Drinking Water Act.

EPA has previously identified PFOA and PFOS on the SDWA’s most recent Contaminant Candidate List, the CCL4, released by EPA on November 17, 2016. [81 FR 81099] 

That same year, the EPA announced health advisories for both PFOA and PFOS, set at 70 parts per trillion. Under the Safe Drinking Water Act, health advisories are non-regulatory and non-enforceable guidance to states and to public water systems.

What Is an MCL?

An MCL is a standard set by US EPA that indicates the maximum concentration of a contaminant that can be present in drinking water and have that water still be deemed “fit for human consumption” for each contaminant.

What Is the Contaminant Candidate List?

Under 1996’s Safe Drinking Water Act Amendment, Congress directed EPA to create a list of contaminants that are:

• Not currently subject to regulation under the SDWA, but

• Are known, or are anticipated, to occur in public drinking water systems and may require SDWA regulation.

The presence of a chemical on the CCL does not automatically indicate that the chemical is regulated or even that it will be regulated in the future. But it is a “heads-up” to public water systems that regulations might be written down the line.

EPA is required to update the CCL every five years. The first version was published in 1998 and the most recent in 2016. The CCL4 includes twelve microbiological contaminants and 97 chemical contaminants or contaminant groups.

How Do Chemicals Go from the CCL to Full Regulation?

EPA is required by law to make regulatory determinations on at least five chemicals on each CCL update. That is, out of the 109 items on the CCL4, EPA must decide whether to create MCLs for at least five of them by November 17, 2021.

The “regulatory determination’ that EPA makes may or may not impose a new MCL. EPA can decide that no action is necessary to protect human health—the decision to not create an MCL also counts as a “regulatory determination,” even though no new rules must be created.

For example, of the five chemicals to receive regulatory determinations from the CCL3 (published in 2009), only one (strontium) was determined to meet the criteria for establishing MCLs. The other four (dimethoate, 1,3-dinitrobenzene, terbufos, and terbufos sulfone) were determined not to meet that criteria.

What Criteria Does EPA Use to Create MCLs?

The SDWA sets three criteria for determining if a contaminant should be regulated:

1. Might the contaminant have an adverse effect on human health?

2. Is the contaminant known to occur (or is there a substantial likelihood it will occur) in public water systems at a frequency and level of public health concern?

3. Does regulation of the pollutant present a meaningful opportunity for the reduction of health risks for people serviced by public water systems?

EPA currently feels that perfluorooctanoic acid and perfluorooctane sulfonate meet these criteria, and the Agency is now beginning the process of establishing MCLs. Unlike the previously established health advisories for PFOA and PFOS, the MCLs—once promulgated—will be regulations and thus enforceable.

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Tags: Act, Clean, EPA, new rules, PFOA, PFOS, Water