Reducing Human Exposure to Highly Fluorinated Chemicals to Protect Public Health

Abstract

Perfluoroalkyl and polyfluoroalkyl substances (PFASs), or “highly fluorinated chemicals,” are a class of persistent compounds used to add nonstick, waterproof, and/or stain-resistant properties to clothing, furnishings, carpeting, cookware, food contact paper, cosmetics, and other consumer products. They are also used in firefighting foams and industrial processes. Of the many chemicals that fall into this category, the so-called “long-chain” PFASs perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been most extensively studied. Hundreds of scientific articles have been published on the toxicity of these two chemicals. Because of their widespread use, persistence, and mobility, they have been detected in the blood of nearly all Americans tested. The drinking water of at least 6 million American residents is contaminated at levels exceeding a 2016 lifetime health advisory issued by the US Environmental Protection Agency. As PFOA and PFOS are phased out of production, hundreds of so-called alternative PFASs with similar chemical structures but limited toxicological/ecological data are replacing them. All PFASs share problematic properties with legacy long-chain PFOA and PFOS and could be considered “regrettable substitutions.” Manufacturers and purchasers should instead select non-PFAS technologies whenever possible. Given the lack of available information on alternative PFASs, further study is needed, and the use of such chemicals should be limited until there is sufficient evidence demonstrating safety. PFAS contamination in drinking water is a growing concern that needs to be addressed; actions should be taken to identify and mitigate sources of PFASs. To protect human and environmental health, exposures to all PFASs should be reduced.

Relationship to Existing APHA Policy Statements

• APHA Policy Statement 9304: Recognizing and Addressing the Environmental and Occupational Health Problems Posed by Chlorinated Organic Chemicals
• APHA Policy Statement 20126: Anticipating and Addressing Sources of Pollution to Preserve Coastal Watersheds, Coastal Waters, and Human Health
• APHA Policy Statement 200011: The Precautionary Principle and Children’s Health
• APHA Policy Statement 20156: Reducing Flame Retardants in Building Insulation to Protect Public Health

Problem Statement

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a category of manmade, highly persistent chemicals that contain one or more aliphatic carbon atoms in which all of the hydrogen substituents have been replaced by fluorine atoms.[1] They are resistant to chemical, physical, and biological degradation, and therefore they break down slowly, if at all, in the environment.[1,2] Even PFASs that partially degrade do not ultimately break down into safe chemicals. PFASs are used to provide nonstick, waterproof, or stain-resistant properties in more than 2,000 products,[3] including outdoor and fashion clothing, cookware, carpets, furniture and furnishings, food contact packaging, and cosmetics. Major sources of PFASs with respect to the environment include industrial processes and military and firefighting operations[4,5] as well as municipal wastewater and biosolids.[6] When added to consumer and other products, PFASs can migrate into air,[7] household dust,[8] food,[9,10] soil, and groundwater and surface water, which can pollute drinking water.[2,11] Currently, a wide range of PFASs are found in the environment,[12] wildlife,[12,13] and human tissue[12,14] all over the globe.

PFASs became commercially available in the late 1940s. The first concerns about the human health risks of perfluorooctanoic acid (PFOA), historically one of the most widely used PFASs, were raised in a 1962 internal DuPont document.[15] By the early 2000s, the results of the National Health and Nutrition Examination Survey revealed the presence of four PFASs, including PFOA and perfluorooctane sulfonate (PFOS), in the bodies of almost all Americans tested.[16] Unlike other persistent organic pollutants, PFASs are found and accumulate primarily in the liver, kidneys, blood serum, and other protein-rich body compartments, instead of in lipids and fatty tissues,[17] and they have been linked to diseases of those organs. PFASs have also been detected in human breast milk, and breastfeeding may be an important source of infants’ exposure.[18]

The PFASs that have been extensively studied, primarily with eight-carbon backbones (“long chain”), have been shown to cause adverse health effects in animal studies, including liver toxicity; disruption of lipid metabolism and immune, reproductive, and endocrine function; adverse neurobehavioral effects; developmental toxicity (including neonatal death); and tumors in several organs.[19] In fact, possible carcinogenicity and immunotoxicity were demonstrated in experimental studies more than 30 years ago.[15] As a result of legal proceedings in the Ohio Valley, probable links have been established between human exposure to PFOA and six diseases: high cholesterol, ulcerative colitis, thyroid disease, testicular and kidney cancers, and pregnancy-related hypertension.[20,21] Although it is difficult to show causality in human epidemiological studies, long-chain PFAS exposure has also been associated with liver malfunction, hypothyroidism, lower birth weight and size, obesity, decreased immune response to vaccines, and reduced hormone levels and delayed puberty.[22] The International Agency for Research on Cancer classified PFOA as possibly carcinogenic to humans in June 2014.[23] Long-chain PFASs can remain for several years in the human body.[15]

In light of known human health impacts and subsequent regulatory involvement, most industrialized countries and areas, notably the United States and the European Union, have seen a recent shift in production from long-chain (generally six or eight carbon atoms or more) to short-chain (six or fewer carbon atoms) PFASs.[1] At the same time, production of long-chain PFASs has moved to the emerging economies in continental Asia.[24] Because of their potential for long-range transport and the worldwide trade of articles that contain them, PFASs contaminate the global environment regardless of where they are produced.[24] While there is still limited information on “alternative” short-chain PFASs, they all share some structural similarity to their long-chain predecessors, and both long- and short-chain PFASs can persist in the environment.[25,26]

As documented in the Helsingør Statement[17] and the Madrid Statement on Poly- and Perfluoroalkyl Substances (PFASs),[22] scientists and other professionals from a variety of disciplines are concerned about the embrace of short-chain PFASs as preferable replacements for long-chain PFASs. Historical precedent suggests that replacing one chemical with another that is structurally similar can lead to similar human and environmental concerns.[25] Highly fluorinated alternatives to PFOA and PFOS, such as short-chain PFASs, may still pose risks to humans and the environment because their structural similarities are expected to give rise to similar hazardous properties (i.e., persistence, toxicity, bioaccumulation potential, and/or long-range transport).[26,27] Manufacturers of short-chain PFASs have not provided evidence or toxicological data that these replacements are safe for human and ecological health. Larger volumes of short-chain PFASs may be necessary to achieve performance levels comparable to those of long-chain PFASs. In addition, short-chain compounds may be more mobile in the environment than their long-chain predecessors,[27] and short-chain PFASs have been linked to adverse impacts such as liver and kidney toxicity in animal studies.[27,28]

Collecting robust health and ecological data on each of the hundreds of alternative PFASs that are emerging as replacements for legacy long-chain PFASs would be time and cost prohibitive. A precautionary approach to regulation and risk management is therefore appropriate for PFASs, especially given the known persistence of this class of compounds.[29] Considering the body of evidence and the support of the scientific community, ethically responsible and collaborative action toward reduced use of all PFASs is needed. There is precedent for acting on the class of PFASs as a whole; for example, in 2015, Biomonitoring California added the entire class of PFASs to its list of designated chemicals (the pool from which chemicals are selected for the state’s biomonitoring program).

Public attention has increasingly been drawn to the health risks of PFASs in drinking water, which is an important pathway for human exposure.[20] In January 2016, New York State’s Departments of Health and Environmental Conservation called the “presence of PFOA in drinking water an emerging nation-wide issue”[30] and urged the US Environmental Protection Agency (EPA) to set a national advisory level. In May 2016, the EPA established a nonregulatory lifetime health advisory of 70 parts per trillion for the combined total of PFOA and PFOS in drinking water.[31] Several individual US states and other countries have also established regulatory and nonregulatory limits for PFOS and PFOA in drinking water using human health risk assessment techniques.[32] On the basis of toxicological studies of the immune system, some scientists have calculated that existing drinking water limits for these two long-chain PFASs may not be adequately health protective and should be much lower.[15] The state of New Jersey recently set an advisory level of 12.5 parts per trillion for PFOA in drinking water. Minnesota has established a health advisory for two short-chain PFASs,[33] but there are currently no other health advisories or limits for short-chain PFASs in drinking water.

PFAS contamination exceeds the EPA’s advisory level in the drinking water of an estimated 6 million, and likely many more, American residents. Drinking water contamination has been linked to firefighting foams used at military sites and airports, industrial sites (including PFAS manufacturers and companies that use PFASs in their products), and wastewater treatment plants.[34] Such sources of contamination are often located in low-income communities, in some cases with few environmental controls, which creates an environmental justice issue.

In addition to drinking water, exposure to PFASs can occur from food consumption and consumer products.[20,35] A recent study revealed levels of PFOS exceeding the European Union limit of 1 µg/m2 in most carpets, outdoor textiles, and leather samples tested, and many other consumer products, including ski waxes, nanosprays (for waterproofing), cleaning agents, and food contact paper, contain high levels of PFASs.[36] Carpets treated with protective coatings that contain PFASs may be a significant source of PFAS exposures in the home. This would be of particular concern in the case of infants and children, who may play on treated carpets; children often ingest disproportionately higher doses (on a body weight basis) of PFASs than adults from the ingestion of food and dust via hand-to-mouth contact.[37] A diverse mixture of PFASs has been found in consumer products.[36]

The economic burden of continued use of and exposure to PFASs may be substantial.[38] While it is challenging to quantify the total costs to society, the example of PFOA provides some indication of lost productivity from, and health care costs incurred through, PFAS-induced health impacts in areas with elevated human exposures. Remediation costs of PFAS contamination are significant and will only grow with the extended use of this class of chemicals.[26] For example, the US military is expected to pay $4.3 million for water filtration to reduce PFAS contamination near Colorado Springs, Colorado, that may have been caused by use of aqueous film-forming foam at a nearby air force base.[39] Chemical producers should take responsibility for researching and sharing health data on alternative PFAS chemicals before they are used in products. However, publicly financed research is also necessary to understand the human and environmental health impacts of legacy and alternative/emerging PFASs.

Evidence-Based Interventions and Strategies

Regulatory efforts thus far have focused primarily on controlling the production of certain long-chain PFASs. For instance, PFOS was added to Annex B (Restriction) of the Stockholm Convention on Persistent Organic Pollutants in 2009[40] and is restricted in the European Union.[41] In 2000, PFOS was voluntarily phased out of production in the United States. A subsequent decrease in US PFOS serum levels is attributed to this phase out.[14] In 2006, the EPA began a PFOA stewardship program under which major US chemical manufacturers agreed to voluntarily discontinue the use and emission of long-chain PFASs by the end of 2015. Such restrictions and agreements have been successful but may contribute to a shift in the manufacture of long-chain PFASs to developing countries.[24] Furthermore, while the use of PFOA and PFOS is decreasing, the production and use of short-chain PFAS alternatives is increasing. As noted, short-chain PFASs should not be considered an improvement over long-chain PFASs without conclusive evidence that they are safe for human and ecological health.

Agreements such as the Montreal Protocol and the Stockholm Convention offer examples of successful international cooperative action to reduce use of and exposures to chemicals of concern. Those agreements have been successful in limiting the use of specific chemicals; however, they have not succeeded in avoiding “regrettable substitutions,” wherein a known harmful chemical is replaced by a similar chemical that is later found to be similarly, if not more, harmful. Broad international action is needed to prevent the regrettable substitution of long-chain PFASs such as PFOS and PFOA with alternative PFASs.

Scientists have made a case for reducing the entire class of PFASs due to the environmental persistence and potential for human health harm from this family of chemicals.[22,42] Strategies that can reduce people’s exposure to all PFASs include eliminating nonessential uses of these chemicals in consumer products and building materials and transitioning to safer alternatives, reducing emissions from manufacturing, and disposing of PFASs and PFAS-containing products in a way that prevents their release into the environment. Companies can use their purchasing power to move the market toward safer alternatives; one successful example is in the furniture industry, which has been phasing out the use of all flame-retardant chemicals in response to regulatory updates and customer demand. Companies including IKEA, Crate and Barrel, and Kaiser Permanente have begun the transition away from PFASs in products they buy, manufacture, and/or sell.[43] More can be done in the private sector to reduce the manufacture and use of PFASs. Development of safer alternatives for current PFAS applications represents an economic opportunity. Given this momentum within industry and the growing government and public awareness, now is an opportune time for collaborative movement toward safer alternatives.

Because drinking water is an important pathway of exposure to PFASs, it is critical to address PFAS contamination in water supplies. Data collected by the EPA between 2013 and 2015 through its Third Unregulated Contaminant Monitoring Rule (UCMR3)[44] show that (as noted) the drinking water of at least 6 million US residents is contaminated with PFOA and PFOS at levels that exceed the EPA’s lifetime health advisory.[15,34] This one-time sampling program monitored for six PFASs, mostly long-chain compounds, in 66 major water supplies across the United States. Given the increasing production of short-chain PFASs, drinking water should be screened for a broader class of PFASs, including those in current production. Local, state, and federal governments can use such data to identify and mitigate sources of pollution, and responsible entities can be held accountable for cleanup efforts. Water cleanup using granular activated carbon (GAC) has been shown to reduce PFOA levels in the serum of exposed populations,[45] but GAC may be less effective for remediation of short-chain PFASs.[2] Appropriate disposal of PFASs and PFAS-containing wastes would also contribute to decreased drinking water contamination.

Opposing Arguments

The FluoroCouncil, which represents the manufacturers of PFASs, claims that only long-chain PFASs are problematic, that short-chain PFASs have “improved health and environmental profiles,” that fluorinated replacements for long-chain PFASs are “safer” and “approved” for use, and that “fluorotechnology is critical to modern life.”[46]

These claims have been rebutted in detail by a group of international scientists.[17,22,42] Because of their comparatively shorter half-lives in humans and animals, it was previously thought that short-chain PFASs would not show up in biological materials. However, researchers in two recent studies found short-chain PFASs and breakdown products of other fluorinated alternatives in fish[47] and in biosludge sometimes spread on agricultural lands.[48] Although some fluorinated alternatives may be less bioaccumulative than long-chain PFASs, many have not yet been evaluated. Accumulation of short-chain compounds is already being observed in the environment.[26] Short-chain PFASs have not been shown to be safe for human and ecological health. Short-chain PFASs have similar environmental persistence to long-chain PFASs and, as noted, have been linked to adverse impacts such as liver and kidney toxicity in animal studies.[27,28]

Despite their lower bioaccumulation potential, short-chain PFASs can lead to global long-term human exposures (for instance, via contaminated drinking water) due to their environmental persistence, potential for long-range transport, and mobility in the aqueous phase.[17] In addition, as mentioned above, there is some concern that greater quantities of short-chain PFASs may be needed to achieve comparable performance to long-chain PFASs.

Nonfluorinated alternatives that are inherently less hazardous to human health and long-term ecosystem health are available for many uses of PFASs, including firefighting foams, durable waterproofing of fabrics, and food contact paper,[49] and many more should be developed. In some cases, the alternative can be as benign as water. For instance, during training exercises at military and air force sites and airports, large volumes of PFASs from firefighting foams wash into surface water and groundwater. The Peterson Air Force Base in Colorado Springs has announced that it is using water for practice drills.[50]

Action Steps

1. Chemical producers should generate and share health and environmental data pertaining to PFASs and nonfluorinated alternatives they develop or manufacture. Industry should disclose the identities, structures, and properties of chemicals it manufactures or uses in its products.
2. Congress should fund, and industry and scientists should prioritize, research on short-chain and other “alternative” PFASs, with a focus on elements such as toxicity, identification in environmental matrices and human tissues, and quantitation in environmental media, human tissues, and products.
3. The EPA, in collaboration with the Agency for Toxic Substances and Disease Registry, should develop health-protective drinking water advisories for PFASs beyond PFOA and PFOS and help establish mitigation strategies in areas where exposures are above health-protective limits.
4. The EPA and other government agencies should continue to monitor for PFASs in drinking water through the UCMR or other large-scale programs. Analyses should include both long-chain and short-chain PFASs, and reporting limits should be lowered.
5. Federal and state agencies should identify sources of PFAS contamination in drinking water, initiate mitigation strategies, and consider regulatory and legal action when appropriate. To facilitate these aims, the EPA should release more detailed location information for UCMR data in regions with high levels of PFASs.
6. State toxics reduction programs, such as the California Safer Consumer Products Program, should prioritize reduction of PFASs to catalyze movement to safer alternatives.
7. Professional and public health organizations should educate purchasers, manufacturers, and retailers about the potential harm of PFASs and the importance of reducing their use and moving to safer alternatives. Manufacturers and major purchasers should encourage the development of nonpersistent, nontoxic, and nonfluorinated alternatives.
8. Federal and state governments should require labeling of PFAS-containing products and building materials to indicate uses and enable consumers to make informed choices.
9. Procurement guidelines for federal, state, and local governments should avoid products with PFASs whenever possible.
10. Federal, state, and local governments should work with industry and public interest groups to ensure that an adequate infrastructure is in place to safely transport, dispose of, and destroy PFASs and PFAS-containing products after their useful life span. Environmental justice should be a central consideration in all decisions.
11. Military and air force bases and airports should use water rather than aqueous film-forming foam for training exercises. Firefighting foams that do not contain PFASs should be used whenever possible. Current stockpiles of firefighting foams that contain PFASs should be reserved for possible use on real fires and otherwise disposed of or managed safely.

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