Extinguishing the Risk of Forever Chemicals: State of the science to protect first responders

Forever Chemicals, aptly named because they are resistant to breaking down, are artificially produced chemicals used to enhance everyday products like stain resistant clothing and furniture, cosmetics, and food packaging material. Scientists refer to them as per- and polyfluoroalkyl substances (PFAS).

PFAS includes thousands of individual compounds that have been used worldwide since the early 1950s. PFAS are used in so many products that we are all exposed to them on some level whether it be through the air we breathe, the soil our food is grown in, the water we drink, or many of the products we use daily like cosmetics or stain- and water-resistant furniture and carpeting. In fact, a 2007 study found that more than 98% of people in the U.S. had PFAS present in their blood. Unfortunately, PFAS exposure has been linked to an increased risk of negative health outcomes such as cancer (kidney and testicular), increased cholesterol levels, and high blood pressure. These findings caught the attention of the first responder community, many of whom are also exposed to PFAS when putting out building and vehicle fires, using special class B foams that put out high-energy liquid fuel fires, and when wearing uniforms and protective clothing that use treatments/additives.

Lawmakers continue to advance legislation while federal and academic organizations launch research efforts to better understand these exposures and the potential risk to first responders. Coordination across these efforts is a priority. A recognized leader in information sharing and partnering within the occupational safety and health community, the National Occupational Research Agenda (NORA) Public Safety Sector Council organized a “meeting of the minds” on May 19, 2021 to discuss the state of research and knowledge on PFAS.  Click here for a video of the meeting.

During the meeting, speakers and guests discussed

• Exposure assessment—collecting and assessing biological, work environment, and product samples to better understand workplace exposures to PFAS
• Toxicology—assessing the relationship between the amount of PFAS entering the body and potential health effects

What’s being done in exposure assessment?

Identifying the specific PFAS compounds of interest is extremely complex because material science is constantly evolving, and product formulations are proprietary. Presenters from the meeting highlighted how they are working together to better identify those PFAS compounds that contribute to workplace exposures. Researchers are collecting biological samples that include serum from volunteer and career (federal and non-federal) firefighters, as well as from numerous communities across the nation—serum is a protein-rich liquid that can be separated from other components of the blood. By collecting from both firefighters and the general public, the researchers will be able to compare levels between the two groups. Researchers are also expanding how they study the collected serum to include more PFAS compounds as they become available for evaluation and to develop ways to collect air samples in workplace settings. Other researchers are looking at changes in epigenetics (how PFAS affect biological functions).

Key takeaways related to exposure assessment included:

• Researchers developed the current methods to study serum samples for PFAS based on what they know about how the general public is exposed. Researchers must expand these methods to include PFAS that are relevant to workplace exposures.
• Some ongoing research presented at the meeting that explores PFAS measured in serum samples suggests that exposures may differ for firefighting sub-groups such as airport, structural, wildland, volunteer, and wildland urban interface. Researchers will need to further explore how this difference in exposure relates to risks for negative health outcomes.
• PFAS are used to repel water in protective clothing such as firefighter turnout gear. Researchers are determining the type and concentration of PFAS in new and used gear and what happens when that gear is put in the laundry. Potentially, PFAS could be released from the gear during cleaning. Additionally, there needs to be exposure assessments for other potential sources and toxicology findings. If concerns exist, the need to update standards for this gear will be explored.
• Most previous research focused on oral exposures (i.e., drinking water), but researchers are now finding that skin (dermal) contact may also be relevant. Exposures may change how well the skin protects from hazards and it may also impact how well the immune system works [1]. Understanding exposure through skin contact will be important to the first responder community as exposure may potentially impact just one area or region of the body (localized) or the whole body (systemic).

What’s happening in toxicology?

As of 2021, researchers completed a toxicological profile (a comprehensive and extensive evaluation, summary, and interpretation of available toxicological and epidemiological information on a substance) for select PFAS. A multi-site study that includes seven communities/areas (over 9,000 people) from across the nation is documenting any ties between PFAS exposure and health outcomes such as kidney function, liver and thyroid disease, and immune response. Similarly, 150 workers from the manufacturing and service sectors are providing biological samples for exposure assessment and will also complete a survey about their negative health outcomes.

The pathway that a toxin takes to enter your body (exposure pathway) is another important piece of the puzzle, as this impacts the body’s response and experience. Researchers are exploring what changes happen to the body based on how well PFAS can pass through the skin.  This involves looking at a variety of factors such as what’s happening with white blood cells and how many cells are in certain tissues in the body or appear to be dying.

Over the past decade, as concerns related to PFAS toxicity increased, product developers explored replacement or alternative PFAS compounds, such as those with shorter carbon chains that the body may be able to remove more quickly. Researchers are comparing the toxicity of the historically used “long-chain” PFAS to these newer “short-chain” PFAS compounds.

 Key takeaways related to toxicology included:

• To understand increased risk for negative health outcomes for workers, it is important to document community and workplace exposure levels—this requires coordination across occupational health, public health, and environmental management organizations.
• PFAS formulations have been evolving from long-chain to short-chain formulations where the amount of carbon in the chain is reduced, thereby presumed to be less toxic. Ongoing research presented at the meeting shows that the relationship between the length of the carbon chain and toxicity may be more complex than initially thought with early work presented at the meeting showing that there is similarity in toxicity of target tissues.
• Epigenetic changes can have long term effects and can sometimes result in the development of disease such as cancer. Initial results presented at the meeting show some PFAS are associated with advanced epigenetic aging, meaning a person’s genes resemble those of an older person rather than a person their own age.

What’s happening in the area where exposure assessment and toxicology meet?

Researchers are developing mathematical models using information collected from research participants on work history and measured exposure. While in the early stages, these models are meant to predict potential exposure levels based on a person’s work history with no need for biological samples. These models are a critical step in the effort to estimate any worker’s risk level for negative health outcomes.

What are the next steps?

The research described in this NORA Public Safety Sector Council session, as well as similar efforts not summarized here, contribute valuable information on PFAS exposure and potential health outcomes for first responders and other worker populations. This research will improve the understanding of who is exposed, how exposures occur, how much they are getting exposed, and where interventions will be the most effective. As the research is completed, researchers will learn more about what first responders can do to protect themselves. Some steps may be taken to limit unnecessary contact with materials known to contain PFAS, such as using training foams instead of Aqueous Film Forming Foam (AFFF) [2-3] during training activities or limiting time wearing turnout gear outside of response or training. Development of PFAS-free class B firefighting foams and turnout gear is underway and undergoing testing to ensure the chemical replacements and product performance will protect fire responders from other known hazards of a fire.

The NORA Public Safety Sector Council will continue to focus on PFAS exposure. Visit the PFAS webpage and the NORA PSS page for more information including worker risks, PFAS resources, and the National Occupational Research Agenda for Public Safety. You can see more about specific projects, including the researchers associated with each effort, by watching the webinar recording.

Susan M. Moore, PhD, is a Coordinator for NIOSH’s Public Safety Sector and a Chair to NORA’s Public Safety Sector Council.

Miriam Calkins, PhD, MS, is an Associate Service Fellow at the NIOSH Division of Field Studies and Engineering.

Stacey Anderson, PhD, is a Research Biologist at the NIOSH Health Effects Laboratory Division.

Crystal Forester, MS, is a Research Chemist at the NIOSH National Personal Protective Technology Laboratory.

Meghan Kiederer, BA, is a Health Communications Fellow at the NIOSH National Personal Protective Technology Laboratory.

References

1. Shane H, Baur R, Lukomska E, Dzubak L, Anderson S [2020]. Immunotoxicity and Allergenic Potential Induced by Topical Application of Perfluorooctanoic Acid (PFOA) in a Murine Model. Food Chem Toxicol.
2. Darwin, R. L. (Hughes Associates). 2004. Estimated Quantities of Aqueous Film Forming Foam (AFFF) in the U.S. Prepared for the Fire Fighting Foam Coalition. Baltimore, MD
3. DOD. 2018. “Qualified Products Database: “Performance Specification: Fire Extinguishing Agent, Aqueous Film-Forming Foam (AFFF) Liquid Concentrate, for Fresh and Sea Water,” MIL-PRF-24385F(SH). January 26. See “View QPD data” link under Revision History. http://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=94307