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Federal Register / Vol. 86, No. 40 / Wednesday, March 3, 2021 / Rules and Regulations
A. PFOS and PFOA

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1. Description Perand polyfluoroalkyl substances PFAS are a class of synthetic chemicals that have been manufactured and in use since the 1940s AAAS, 2020; USEPA, 2018b. PFAS are most commonly used to make products resistant to water, heat, and stains and are consequently found in industrial and consumer products like clothing, food packaging, cookware, cosmetics, carpeting, and fire-fighting foam AAAS, 2020. PFAS manufacturing and processing facilities, facilities using PFAS in production of other products, airports, and military installations have been associated with PFAS releases into the air, soil, and water USEPA 2016b;
USEPA 2016c. People may potentially be exposed to PFAS through the use of certain consumer products, through occupational exposure, and/or through consuming contaminated food or contaminated drinking water Domingo and Nadal, 2019; Fromme et al. 2009.
Perfluorooctane sulfonate PFOS and perfluorooctanoic acid PFOA are part of a subset of PFAS referred to as perfluorinated alkyl acids PFAA and are two of the most widely studied and longest-used PFAS. Due to their widespread use and persistence in the environment, most people have been exposed to PFAS, including PFOA and PFOS USEPA 2016b; USEPA 2016c.
PFOA and PFOS have been detected in up to 98% of serum samples taken in biomonitoring studies that are representative of the U.S. general population CDC, 2019. Following the voluntary phase-out of PFOA by eight major chemical manufacturers and processors in the United States under EPAs 2010/2015 PFOA Stewardship Program and reduced manufacturing of PFOS last reported in 2002 under Chemical Data Reporting, serum concentrations have been declining. The National Health and Nutrition Examination Survey NHANES data exhibited that 95th-percentile serum PFOS concentrations have decreased over 75%, from 75.7 mg/L in the 1999
2000 cycle to 18.3 mg/L in the 2015
2016 cycle CDC, 2019; Jain, 2018;
Calafat et al., 2007; Calafat et al., 2019.
2. Agency Findings The Agency is making a determination to regulate PFOA and PFOS with a NPDWR. EPA has determined that PFOA and PFOS may have adverse health effects; that PFOA
and PFOS occur in public water systems with a frequency and at levels of public health concern; and that, in the sole judgment of the Administrator,
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regulation of PFOA and PFOS presents a meaningful opportunity for health risk reduction for persons served by public water systems.
a Adverse Health Effects The Agency finds that PFOA and PFOS may have adverse effects on the health of persons. In 2016, EPA
published health assessments Health Effects Support Documents or HESDs for PFOA and PFOS based on the Agencys evaluation of the peer reviewed science available at that time.
The lifetime Health Advisory HA of 0.07 mg/L is used as the HRL for Regulatory Determination 4 and reflect concentrations of PFOA and PFOS in drinking water at which adverse health effects are not anticipated to occur over a lifetime. Studies indicate that exposure to PFOA and/or PFOS above certain exposure levels may result in adverse health effects, including developmental effects to fetuses during pregnancy or to breast-fed infants e.g., low birth weight, accelerated puberty, skeletal variations, cancer e.g., testicular, kidney, liver effects e.g., tissue damage, immune effects e.g., antibody production and immunity, and other effects e.g., cholesterol changes. Both PFOA and PFOS are known to be transmitted to the fetus via the placenta and to the newborn, infant, and child via breast milk. Both compounds were also associated with tumors in long-term animal studies USEPA, 2016d; USEPA, 2016e; NTP, 2020. For specific details on the potential for adverse health effects and approaches used to identify and evaluate information on hazard and dose-response, please see USEPA, 2016b; USEPA, 2016c; USEPA, 2016d;
USEPA, 2016e.
b Occurrence EPA has determined that PFOA and PFOS occur with a frequency and at levels of public health concern at PWSs based on the Agencys evaluation of available occurrence information. In accordance with SDWA
1412b1BiiII, EPA has determined monitoring data from the third Unregulated Contaminant Monitoring Rule UCMR 3 are the best available occurrence information for PFOA and PFOS regulatory determinations. UCMR
3 monitoring occurred between 2013
and 2015 and are currently the only nationally representative finished water dataset for PFOA and PFOS. Under UCMR 3, 36,972 samples from 4,920
PWSs were analyzed for PFOA and PFOS. The minimum reporting level MRL for PFOA was 0.02 mg/L and the MRL for PFOS was 0.04 mg/L. A total of
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1.37% of samples had reported detections greater than or equal to the MRL of at least one of the two compounds. To examine the occurrence of PFOS and PFOA in aggregate, EPA
summed the concentrations detected in the same sample to calculate a total PFOS/PFOA concentration. EPA notes that the reference doses RfDs for both PFOA and PFOS are based on similar developmental effects and are numerically identical; when these two chemicals co-occur at the same time and location in drinking water sources, EPA
has recommended considering the sum of the concentrations USEPA, 2016d;
USEPA, 2016e and has done so for this regulatory determination. The maximum summed concentration of PFOA and PFOS was 7.22 mg/L and the median summed value was 0.05 mg/L.
Summed PFOA and PFOS
concentrations exceeded one-half the HRL 0.035 mg/L at a minimum of 2.4%
of PWSs 115 PWSs and exceeded the HRL 0.07 mg/L at a minimum of 1.3%
of PWSs 63 PWSs 3. Since UCMR 3
monitoring occurred, certain sites where elevated levels of PFOA and PFOS were detected may have installed treatment for PFOA and PFOS, may have chosen to blend water from multiple sources, or may have otherwise remediated known sources of contamination. Those 63
PWSs serve a total population of approximately 5.6 million people and are located in 25 states, tribes, or U.S.
territories USEPA, 2019a. Data from more recent state monitoring discussed below demonstrate occurrence in multiple geographic locations consistent with UCMR 3 monitoring and support the Agencys final determination that PFOA and PFOS occur with a frequency and at levels of public health concern in finished drinking water across the United States. The Final Regulatory Determination 4 Support Document presents a sample-level summary of the results for PFOA and PFOS individually and includes discussion on state monitoring efforts as well as uncertainties in occurrence data USEPA, 2021a.
Consistent with the Agencys commitment in the PFAS Action Plan the Agencys first multi-media, multiprogram, national research, management, and risk communication plan to address a challenge like PFAS
to present information about additional sampling efforts for PFAS in water systems, the Agency has supplemented its Unregulated Contaminant Monitoring Regulation UCMR data 3 Sum of PFOA + PFOS results rounded to 2
decimal places in those cases where a laboratory reported more digits.

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