The Safe Drinking Water Act (SDWA) protects public drinking water supplies across the United States. Under the SDWA, the US Environmental Protection Agency (EPA) has regulated more than 90 drinking water contaminants , and can set Maximum Contaminant Levels (MCLs) for specific chemicals and require monitoring of public water supplies. The SDWA applies only to US public water systems and does not apply to domestic drinking water wells. Currently, no MCLs have been established for PFAS chemicals. By proposing a contaminant's addition to the Containment Candidate List (CCL), no requirements are imposed on public water systems. However, EPA has initiated steps to evaluate the need for an MCL for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) under the regulatory determination process .
To date, there have been many toxicology studies on the short- and long-term implications of PFOA and PFOS exposure. EPA is leveraging consistent test results to begin defining how regulations can improve exposure implications for people and the environment. In this article, we provide an overview of these chemical compounds and their implications to the environment, and the regulatory actions that have been taken to date.
PFOA (Figure 1) and PFOS (Figure 2) are perfluoroalkyl substances (PFAS) that have been in wide use since the 1950s in multiple industrial applications, in part due to their unique surfactant properties. They are extremely valuable in coatings and surface protectant formulations because they are both water- and oil-repelling, and quite resistant to heat and chemical agents. According to the 2009 OECD survey, the most common use of perfluorinated chemicals is in the production of water/oil repellent products. In addition to coatings, other common uses include textile stain guards, grease-proof paper, and aqueous film-forming foams (ARCADIS2016).
PFOS is actually a complex mixture of straight chain and branched chain structures, with the straight chain molecule (shown above) being the most prevalent at about 70%.
This same highly stable carbon-fluorine bond that has contributed to the value of these chemicals in industrial applications also makes them difficult to degrade in the environment. Concern around their environmental effects began in the 1990s when it was recognized that certain PFAS are highly environmentally persistent, potentially bio-accumulative, and possibly toxic to humans and wildlife. While many of these chemicals have been detected globally in the environment, in food, and in human and aquatic biological tissues, most of the regulatory and other attention has been focused on PFOA and PFOS. These two chemicals have been determined to be ubiquitous in the environment and in various living organisms. In addition to environmental persistence, the PFAS, in general, have been shown to undergo bio-magnification, the degree being related to the perfluorocarbon chain length.1
Recognizing this environmental persistence, potential for bio-magnification, and undesirable toxicological properties, particularly of the longer chain molecules, the current trend among global manufacturers is to replace the longer chain PFAS with shorter chain perfluoroalkyl chemicals (GenX chemicals) and with non-perfluoroalkyl chemicals.
Humans may be exposed to PFOA and PFOS through multiple ways. Certainly workers can be exposed during production, but non-worker populations may also be exposed to chemicals that have entered the air, food and drinking water (ATSDR 2016).
- The most common exposure to the general public is believed to occur via eating contaminated food. Humans may also be exposed through use of contaminated food-related products.
- Drinking water may also be a source of exposure but it is believed that this is typically localized to communities in surrounding areas where PFOA/PFOS were used or produced.
- While essentially non-volatile, PFOA/PFOS may bind to air particulates, so exposure through air is also possible, especially in areas with close proximity to atmospheric emission sources.
- Exposure through dermal contact is not considered to be an important route of exposure since PFAS are not well absorbed through skin, although dermal exposure could be a relevant route of exposure for workers.
- Fetuses/infants may come in contact with these chemicals through maternal exposure. A specific concern for infants is related to the finding that PFOA levels in maternal blood decreased during lactation, whereas levels of PFOA in 6-month old infants were 4.6 times higher than that in maternal blood at birth.
Numerous biomonitoring studies have been conducted in which the level of PFAS in humans has been determined. Elevated PFAS levels have been observed in certain populations based on proximity to industrial sites where PFAS are used, proximity to airports using Aqueous Film-Forming Foams (AFFF), accidental releases, and groundwater contamination. See Figure 3 for more illustrative detail.
According to the Interstate Technology Regulatory Council (ITRC), there are four main sources of PFAS in the environment:
- Fire training / fire response sites
- Industrial sites
- Wastewater treatment plants / bio solids
AFFF are surfactant solutions that are used commercially to extinguish hydrocarbon fires (ITRC 2018). The exact composition of any given AFFF is highly variable, and different processes may be used to produce the fluorosurfactants used in these materials. Those produced by electrochemical fluorination are the main source of PFAS at sites where AFFF is used.
PFAS may be released from industrial sites where PFAS are being produced, where they are used in production of other chemicals, or where they are part of a secondary process, such as coating of finished products. Industrial waste and consumer products containing PFAS can ultimately end up in landfills from which PFAS can leach into groundwater, where PFAS with fewer than eight carbon atoms tend to be the most common PFAS to leach into groundwater.
Finally, PFAS can enter the environment from wastewater treatment plants by a variety of pathways where they may be produced or concentrated during the various steps in the treatment process. Transport of PFAS in the environment has been widely studied, particularly for PFOA and PFOS. These chemicals have been found in humans and fish and other wildlife throughout the environment, even in some very remote areas, including the Arctic Ocean. While these chemicals are known to accumulate in exposed fish and wildlife, any actual effects on these exposed animals is largely unknown. Studies on fish consumption have shown that the accumulation of PFAS in fish ultimately contributes to human exposure (ARCADIS 2016).
Absorption, Distribution, Metabolism, Excretion (ADME)
The majority of toxicity data on PFAS has been generated on PFOA/PFOS, along with a growing body of data on perfluorohexane sulfonate (PFHxS) (ARCADIS 2016). The reason for this is the known ubiquitous nature of these particular chemicals in the human body and in the environment.
PFOA and PFOS are well absorbed from the gastrointestinal tract from which they generally partition into protein-rich tissue, including blood, liver and kidneys. They are very slowly excreted with estimated half-lives for PFOA and PFOS in humans of 3.8-4.4 and 8.7 years, respectively.
Both chemicals can cross the placenta, and trace amounts have also been found in human breast milk. Given the long half-lives due to their lack of metabolism and slow excretion, PFOA/PFOS accumulate in the body where they remain for years after exposure ends.
Measured concentrations of PFAS in the general population demonstrate that levels in human serum have declined between 1999-2000 and 2013-14, presumably due to the phase-out of their manufacture and use.
There is no data available with regard to acute toxicity in humans, though animal studies have demonstrated moderate acute toxicity following ingestion of PFOA and PFOS. In general, PFOS tends to be more toxic than PFOA. There is limited human data with respect to chronic toxicity and PFOA/PFOS exposure. PFOS has been shown to affect levels of thyroid hormone (T3) and cholesterol in humans, though the studies are not definitive. In fact, there is inconsistency, in general, when looking at epidemiological studies of PFAS.
Epidemiology studies suggest possible associations of PFOA/PFOS and certain cancers, though these studies are considered inconclusive (PHE 2009).
- An association of PFOS exposure and bladder cancer was confounded by an accessory exposure to the known bladder carcinogen, benzidine. Similarly, individuals who were considered highly exposed to PFOS based on length of employment had an increased risk of certain cancers (gastrointestinal, biliary, reproductive tract) compared with unexposed controls.
- In two studies with workers exposed to PFOA, an elevated rate of mortality from prostate cancer was seen, whereas one of the studies also showed a small increase in pancreatic and large intestinal cancers.
- An increase in bladder and kidney cancers was seen in another smaller study.
- Two separate carcinogenicity studies in male and female rats demonstrated a significant positive correlation between long-term PFOS exposure and the formation of benign liver tumors.
Weighing all of the evidence, the US EPA concluded that evidence for carcinogenicity of PFOS and PFOA is “suggestive,” but not definitive (US EPA 2016).
According to the Agency for Toxic Substances and Disease Registry (ATSDR), a suggestive link between serum levels of PFOA/PFOS and an increased risk of decreased fertility has been found in epidemiology studies. ATSDR further concluded that there is a suggested link between human serum levels of these two chemicals and decreases in birth weight.
Regulatory Activities within the United States
On May 25, 2016, EPA issued a health advisory for PFOA and PFOS and declined to include four other PFAS compounds in that health advisory based on available sampling data at that time. The health advisory level was established as 0.07 parts per billion (70 parts per trillion), which is the concentration of PFOA and PFOS in drinking water at or below which adverse health effects are not anticipated to occur over a lifetime of exposure. EPA's health advisory is non-enforceable but is used to provide technical information to state agencies and other public health officials on health effects, analytical methodologies, and treatment technologies associated with drinking water contamination.
Since the issuance of this health advisory but no enforceable federal actions as of yet, many states have adopted the federal health advisory or established state-level drinking water standards of equal or more stringent value. For instance, states such as California, Minnesota, New Jersey and Vermont have established lower PFOA and PFOS standards ranging from 0.013 to 0.035 parts per billion. See Table 1 for more details.
|Table 1. Drinking Water/Groundwater Screening Levels (µg/l) for PFOS and PFOA|
|States that have adopted US EPA Health Advisory (2016/2018) or developed drinking water standards of equal value:||0.07||0.07|
|Alabama (ADEM 2018)||Maine (CDC 2016)|
|Alaska (DEC 2018)||Massachusetts (DEP 2018)|
|Arizona (DEQ 2018)||Michigan (DEQ 2018)|
|Colorado (DPHE 2017 & 2018)||New Hampshire (NHDES 2016)|
|Connecticut (DPH 2016)||Pennsylvania (DEP 2018)|
|Delaware (DNREC 2016)||West Virginia (OEHS 2018)|
|Iowa (IDNR 2016)||Rhode Island (DEM 2018)|
|California (SWRCB 2018)||0.014||0.013|
|Minnesota (MDH 2019)||0.035||0.015|
|New Jersey (DWQI 2017 & 2018)||0.014||0.013|
|Nevada (DEP 2015)||0.667||0.667|
|Texas (CEQ 2018)||0.29||0.56|
|Vermont (DEC/DOH 2018)||0.02||0.02|
|Information in this table was obtained from https://pfas-1.itrcweb.org/fact-sheets/ as of July 15, 2019.|
Moving forward to 2019, EPA proposed a federal action plan to address PFAS pollution. The plan is a multi-media, multi-program, national research and risk communication plan which includes the following elements:
- Establishing Maximum Containment Levels (MCL) for PFOA and PFOS in drinking water.
- Gathering information to determine whether a broader class of PFAS needs to be regulated.
- Developing cleanup strategies, such as designating PFOA and PFOS as hazardous substances and developing interim groundwater cleanup recommendations.
- Potentially adding PFAS to the Toxic Release Inventory (TRI) and developing regulations to prohibit use of certain PFAS.
- Proposing nationwide drinking water monitoring for PFAS.
- Expanding research of PFAS in order to manage risks.
- Developing new analytical methods so that more PFAS chemicals can be detected.
- Analyzing new technologies and treatment options for contaminated drinking water sites.
- Using federal enforcement tools to support state agencies where PFAS exposure is an issue.
- Developing a risk communication toolbox.
On April 25, 2019, EPA released draft interim guidance for addressing groundwater contaminated with PFOA and/or PFOS for public review and comment. The guidance provides screening levels that can be used to determine if levels of contamination may warrant further study. The guidance also provides preliminary remediation goals (PRGs) to provide initial targets for cleanup that can be adjusted on a site-specific basis. Comments on the draft guidance were due June 10, 2019.
Senators Debbie Stabenow and Marco Rubio introduced the PFAS Accountability Act on May 8, 2019. The legislation's goal is to hold the Department of Defense and other federal agencies accountable for faster relief to affected communities. Several bills were introduced in the house on this issue as well. These bills aim to list PFAS as a Hazardous Air Pollutant (H.R. 2605), force PFAS manufacturers to pay a user fee (H.R. 2570) and include PFAS in the annual Toxic Release Inventory (H.R. 2577). House Bill 2533 would create a grant program to remove chemicals used in firefighting foam from drinking water.
Regulatory Activities across Parts of Europe
In 2008, essentially all uses of PFOA and PFOS were banned in the EU under Directive 2006/122/EU (PHE 2009). Then in 2009, PFOS was added to the list of Persistent Organic Pollutants under the Stockholm Convention (Annex B), and since that date, its use has been restricted in signatory countries (Stockholm Convention n.d.). PFOS and its salts are still acceptable for specific applications for which there are currently no suitable alternatives.
Since June 27, 2011, the EU has banned the use of fire-fighting foam products containing >0.001wt% PFOS. The EU Directive “Environmental Quality Standards” (EQSD), promulgated in 2013, set the criterion for the annual average environmental quality standard for PFOS in surface waters at the extremely low level of 0.00065 µg/l. This value is set to prevent the potential for human poisoning related to consumption of PFOS in fish. The EU compliance deadline is December 27, 2027. Enforcement will require the development of new monitoring methods, as commercial laboratories may be unable to detect these low levels. Certain EU member states have developed provisional drinking water standards; these are typically in the range of 0.1 to 0.5 µg/l PFOS.
Federal Regulatory Activities Impacting Industries
Recognizing the environmental persistence, potential for bio-magnification, and undesirable toxicological properties, particularly of the longer chain molecules, the EPA launched a PFOA Stewardship Program in 2006 under which eight major manufacturers of long-chain PFAS committed to reduce PFOA from their global facility emissions and product content by 95% no later than 2010, and work toward total elimination from these sources by 2015, and these eight global manufacturers met the goals of the program.
Then in 2015, EPA proposed to amend a Significant New Use Rule (SNUR) for long-chain perfluoroalkyl carboxylate (LCPFAC) chemical substances. This SNUR requires manufacturers of an identified subset of LCPFAC to notify EPA at least 90 days before commencing manufacturing or processing. The notifications give EPA the opportunity to evaluate the intended use and, if needed, protect against potential risk for the environment. This action may also affect certain entities through pre-existing import certification and export notification rules under Toxic Substances Control Act (TSCA).
As of early 2019, with the wealth of recent activity surrounding PFAS with regard to drinking water, but no established federal regulatory actions yet, the local regulatory entities are left with no concrete path forward. In that void, some states have established their own advisories, or drinking water standards, some of which are more stringent than the federal health advisory of 0.070 parts per billion for PFOA/PFOS. This has led to further confusion and questions surrounding the quality of drinking water, potential health effects across states and communities, and compliance requirements for the industry.
As seen by a first-ever comprehensive national action plan by the EPA, coupled with recent states' actions, there may be an increase in federal scrutiny of impacted industries that goes beyond a SNUR 90-day notification. Trinity is closely monitoring this activity in order to help their clients prepare for potential operational impacts under impending federal and state regulations. For further information or to receive regular updates, please contact us at +1 (866) 830-0796 or complete our Contact Us form on our website.
1 OECD defines long-chain molecules as carboxylates like PFOA with ≥7 perfluoroalkyl carbons, and sulfonates like PFOS with ≥7 perfluoroalkyl carbons (OECD 2013).