A potential solution to removing a persistent pollutant


By: Dana Sackett

In this week’s article I wanted to revisit a topic we covered in 2014 and share some potentially promising new information. That topic involved a group of man-made chemicals found in non-stick/non-stain, fire retardant and firefighting products known as poly- and perfluorinated compounds (PFCs). Our previous article discussed the emerging problems associated with these chemicals for the aquatic environment, the species that live there, and for people (see our previous article here). While additional data further reveals the details the impact of these widespread and persistent chemicals have, there is new hope that scientists may have developed a potential solution to help filter out these pollutants. 

Sources of PFCs. Source: McElnay C., Weir R. 2018. Heath Effects of PFAS. Ministry of Health. https://slideplayer.com/slide/15215349/

PFCs have been widely used for over sixty years in numerous products that advertise resistance to oil, grease, stains, and water, as well as for fighting aviation fires at military bases and airports.  These highly stable chemicals were first thought to be inert and therefore of very low toxicity. However, approximately thirty years ago studies examining the toxicity of these compounds began to report immunotoxic and carcinogenic affects.  Following these reports PFCs were found in exposed workers, the general population, and water supplies.  More recently, some specific PFCs that are better known by their acronyms PFASs, PFOSs, and PFOAs have been found in nearly every water body, fish, and community tested.  For instance, PFCs such as PFOS and PFAS have been found in water, sediment, aquatic invertebrates, fish, and people in numerous countries (throughout the United States, Vietnam, Japan, Greece, Norway, China, and Germany, just to name a few).

Source: Grandjean and Clapp 2015

Perhaps what’s more troubling is that these chemicals are currently thought to be the most persistent of any pollutant.  Their otherwise useful properties (their ability to remain inert under widespread thermal, chemical, and biological conditions) also make these pollutants very difficult to breakdown in the environment. These properties come from the strong carbon-fluorine bonds which cause PFAS specifically to be highly persistent in the environment and animals (including fish and people), and allows various forms of this pollutant to be easily transported through the soil to groundwater and even evaporate into the atmosphere.

PFOA chemical structure. The strong carbon-fluorine bonds are what make these chemicals so persistent in the environment. Source: https://www.niehs.nih.gov/health/topics/agents/pfc/index.cfm

People are primarily exposed to these pollutants by consuming contaminated water and fish that bioaccumulate these chemicals from their own diet. Bioaccumulation is when animals higher in a food web accumulate a higher concentration of a pollutant through consuming contaminated food and water. Further, while PFOS use was phased out in 2002 and some manufactures agreed to phase out PFC use by 2015, many manufacturers are still using PFCs in products today. 

How PFCs cycle through the environment. Source: https://gesonline.com/insights/2018-01-12/pfas-primer

While this news seems grim, there is some hope that we may be on the verge of a better solution to getting these chemicals out of our water and eventually out of our food and ourselves.  Because these chemicals do not breakdown in any meaningful way in the environment, the next best way to get them out is using a filtration system. Currently, the most common way to filter water is to use activated carbon.  This universal method does a moderately good job of removing some PFCs from water, but thus far carbon filters have fallen short of helping to solve the current ubiquitous contamination of our water ways.

As a military spouse myself, the results seen above and described in the source article are quite concerning. Source: https://pfasproject.com/2018/12/02/pfas-contamination-on-military-bases-is-a-scary-reality-and-for-me-its-personal/

Scientists have very recently developed a new material specifically made to attract PFC materials and PFOAs specifically.  This material is a polymer that links a large ring-shaped molecule made from corn starch and a fluorine-rich molecule called DFB together. This material does a much better job of attracting PFOA in filters.  Specifically, this new material was able to remove 95% of the PFOAs from water while activated carbon only removed 50%. Removing PFOAs from drinking water and surface waters by using these new methods in water treatment will be helpful in preventing these chemicals from continuing to persist and increase in water, fish, and people. 

Estimates of how long it will take after widespread filtration systems are in place for blood levels of PFOA in people (exposed through consuming contaminated water, fish, and other sources) to decline. Source: https://www.health.ny.gov/environmental/investigations/hoosick/docs/pfoa_blood_sampling_q_and_a_8-1-16.pdf and based on Bartell et al. 2010.

While scientists are not yet at a point where they will be able to incorporate these filtration methods into water treatment, this research provides hope that we may be able to rectify the growing global contamination of our water and fish from these chemicals in the near future. Some scientist also believe that the current safety standards for drinking water and consumption (a benchmark amount of PFCs in water and food below which is it considered safe for people) are still based on incomplete evidence.  This is a problem because risk evaluations often assume that untested effects do not require safety regulations, embodying the old adage “What we don’t know can’t hurt us.”  This approach can greatly underestimate the health risks from these chemicals; making the discovery and widespread use of a filtering system that can remove these chemicals from our ecosystems that much more vital.

References and other reading material:

Bartell SM, Calafat AM, Lyu C, Kato K, Ryan PB, Steenland K. 2010. Rate of decline in serum PFOA concentrations after granular activated carbon filtration at two public water systems in Ohio and West Virginia. Environmental Health Perspectives 118: 222-228.

Christensen KY, Raymond M, Blackowicz M, Liu Y, Thompson BA, Anderson HA, Turyk M. 2017. Perfluoroalkyl substances and fish consumption. Environmental Reasearch 154: 145-151.

Grandjean P and Clapp R. 2015. Perfluorinated Alkyl Subtances: emerging insights into health risks. NEW SOLUTIONS: A Journal of Environmental and Occupational Health Policy 25: 147–163.

Guerranti C, Cau A, Renzi M, Badini S, Grazioli E, Perra G, Focardi SE. 2016. Phthalates and perfluorinated alkylated substances in Atlantic bluefin tuna (Thunnusthynnus) specimens from Mediterranean Sea (Sardinia, Italy): Levels and risks for human consumption. Journal of Environmental Science and Health 51: 661-667 DOI: 10.1080/03601234.2016.1191886.

Hamers L. 2017. New material could filter water contaminants that others miss. Chemicals from nonstick manufacturing have been difficult to clean up. https://www.sciencenews.org/article/new-material-could-filter-water-contaminants-others-miss

He X, Dai K, Li A, Chen H. 2015. Occurrence and assessment of perfluorinated compounds in fish from the Danjiangkou reservoir and Hanjiang river in China. Food Chemistry 174: 180-187.

Hu XC, et al. 2016. Detection of poly- and perfluoroalkyl substances (PFASs) in U.S. drinking water linked to industrial sites, military fire training areas, and wastewater treatment plants. Environmental Science and Technology Letters. 3: 344 doi: 10.1021/acs.estlett.6b00260.

Jeong Y-J, Bang S, Kim J, Chun S-H, Choi S, Kim J, Chung M-S, Kang GJ et al. 2019. Comparing levels of perfluorinated compunds in processed marine products. Food and Chemistry Toxicology 126: 199-210.

Lam N, Cho C, Kannan K, Cho H. 2017. A nationwide survey of perfluorinated alkyl substances in waters, sediment and biota collected from aquatic environment in Vietnam:Distributions and bioconcentration profiles. Journal of Hazardous Materials 323: 116-127.

Raloff J. 2012. ‘Nonstick’ pollutants may cut efficacy of vaccines in kids. Science News. 181:  15.

Rappazzo KM, Coffman E, Hines EP. 2017. Exposure to perfluorinated alkyl substances and health outcomes in children: a systematic review of the epidemiologic literature. International Journal of Environmental Research and Public Health 14: 691.

Vassiliadou I, Costopoulou D, Kalogeropoulos N, Karavoltsos S, Sakellari A, Zafeiraki E, Dassenakis M, Leondiadis L. 2015. Levels of perfluorinated compiunds in raw and cooked Mediterranean finfish and shellfish. Chemosphere 127: 117-126.

Vidal A, Lafay F, Daniele G, Vulliet E, Rochard E, Garric J, Babut M. 2019. Does water temperature influence the distribution and elimination of perfluorinated substances in rainbow trout (Oncorhynchus mykiss)? Environmental Science and Pollution Research 26: 16355-16365.

Xiao L. et al. 2017. β-cyclodextrin polymer network sequesters perfluorooctanoic acid at environmentally relevant concentrations. Journal of the American Chemical Society. 139: 7689 doi: 10.1021/jacs.7b02381.

Xiao X. et al. 2017. Sorption of poly- and perfluoroalkyl substances (PFASs) relevant to aqueous film-forming foam (AFFF)-impacted groundwater by biochars and activated carbon. Environmental Science and Technology. 51: 6342 doi: 10.1021/acs.est.7b00970.



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