Public Health Risks to First Responders

Summary

There is growing evidence that firefighters (FF) are being exposed to per- and polyfluoroalkyl substances (PFAS) associated with their gear.  The source of the PFAS may be from their gear’s (FFG) construction materials or manufacturing process, deterioration of the FFG during service, and/or deposition on the FFG while on duty.  This study will conduct research to understand the type, prevalence, and concentration of PFAS on the FFG, the source of PFAS, and the mechanism for PFAS release, which will be critical to reducing the Firefighter’s risk of being exposed to PFAS from their gear.

Description

OBJECTIVE: 

To identify a firefighter’s relative risk of exposure to per- and polyfluoroalkyl substances (PFAS) released from their protective gear.

TECHNICAL IDEA:

The new technical idea is to determine the type, root source, and release mechanism of PFAS from FFG, which could be used to restrict the types of materials used in FFG and require new cleaning, handling, and storage of FFG in order to reduce FFs from being exposed to PFAS.

Per- and polyfluoroalkyl substances (PFAS) are a family of at least 3000 man-made small to polymeric chemicals consisting of a highly fluorinated carbon backbone and possibly other functional groups.   Because of PFAS’s high chemical and thermal stability and performance properties (such as stain and water repellant, and surfactant characteristics), PFAS has been used for decades in a wide variety of consumer and commercial applications, such as

• nonstick pans, waterproof jackets, upholstery and carpets, cleaning products, food packaging, personal care products (e.g., sunscreen and shampoos)
• processing aids, electrical wire casing, fire and chemical resistant tubing, firefighting foams

These same chemical and physical attributes that make PFAS valuable for consumer and commercial applications also make it an environment and health safety concern.  PFAS has the ability to easily enter and travel throughout our eco-system where it can accumulate over years and, when it enters our bodies, can result in serious health issues, such as kidney and testicular cancer, immune suppression, thyroid dysfunction and gestational hypertension. 

Studies have reported the presence of high levels of PFAS in firefighter’s blood.  It has been proposed that the PFAS source is from the fire scene (AFFF, buildings contents, etc.), and/or from the FFG itself.  As a result of these findings, two Senate Bills were introduced to reduce firefighters’ exposure to PFAS.  Protecting Firefighters from Adverse Substances (PFAS) Act of 2019 (Bill S2353) directs FEMA, EPA, USFA, and NIOSH to develop educational resources to help protect firefighters, emergency response personnel, and the communities they serve from PFAS exposure.  Public Health Risks to First Responders (PFAS) Act of 2019 directs NIST to conduct research to determine the relative risk of firefighter’s exposure to PFAS. 

RESEARCH PLAN:

This study has four main tasks.  Task 1 will be to characterize PFAS associated with off-the-shelf new-FFG (e.g.; jacket, pants, gloves, self-contained breathing apparatus).  Task 2 will be to characterize PFAS released/developed in FFG after stressing. Stressing is intended to mimic typical wear-and-tear conditions while a FF is on duty (e.g., elevated temperatures, abrasion, and laundering).  Task 3 will be to characterize PFAS found at a fire scene and on FFG after exposure to a fire scene.  Understanding not only what PFAS species are identified but the source of the PFAS is essential to developing strategies to reducing FF’s risk of being exposed to PFAS.  Task 4 will be to coordinate and collaborate our research with the existing PFAS research community who are studying PFAS from AFFF, human health effects from PFAS exposure, etc..  The purpose of this is to use our data to help in the development of a comprehensive strategy to reduce/eliminate FF exposure to PFAS.

Task 1: PFAS from New-FFG
There are two possible sources for PFAS found on FFG – from the gear itself (existing or a result of gear degradation) or the fire scene.  This section describes PFAS characterization of off-the-shelf new-FFG.

It is believed that new-FFG may contain PFAS.  PFAS may be a compositional component of the FFG (e.g., Teflon® moisture barrier and PFAS-based water repellent coating on the outer shell, Figure 6) or a residual leftover from the manufacturing process (recall; small molecules PFAS is used as processing aid).  It is recommended that a study to better understand the risk of FFs being exposed to PFAS should start by establishing a baseline understanding of PFAS associated with new-FFG.  The objectives of this task should include the following:

• determine which parts of the FFG contain PFAS
• determine the type and concentration of PFAS released by extraction of the new-FFG
• determine the type and concentration of PFAS released by stressing of new-FFG (airborne and extraction analyses)

The FFG which could be studied for PFAS include the following.

• Jacket and pants (outer shell, moisture barrier, and thermal liner)
• Hood
• Gloves and boots
• Mask
• Breathing tube
• Air tank

Prioritizing the FFGs should be based on which are the most likely to contain/release PFAS (based on current data, analysis screening, etc.) and collect/retain PFAS generated at the fire scene.  Based on this, it is recommended that the FFG should be prioritized as listed.  The rational for this is that the first three have a water-repellant coating (known source of PFAS) and/or may use PFAS in their manufacturing process, and the moisture barrier (MB) is constructed on Teflon®.  To the best of our knowledge there is no documented evidence that the later three contain PFAS.  However, there is speculation PFAS may have been used in the manufacturing process of the breathing tubes and flexible portion of the mask.  Therefore, it is recommended that the mask and breathing tubes should at least be screened for PFAS.

In this study, characterizing PFAS on as-received new-FFG will involve liquid extraction (e.g., methanol) of the new-FFG and analyzing the extractate with LC-MS.  It will also include taking alcohol wipe samples (e.g., Fisher Scientific North Alcohol Wipers) of the new-FFG to determine if this approach is a viable alternative when FFG cannot be extracted such as in analyzing FFG while in the field.  The wipes will be extracted and the extractate analyzed using LC-MS.  The new-FFG will also be soaked in artificial sweat to determine what PFAS might dissolve in FF sweat.  These PFAS may be of higher concern for dermal absorption.  The sweat extraction solution will then be analyzed by LC-MS (with or without additional work-up)

Task 2. Stressing new-FFG to generate and release PFAS
The activities described in the “PFAS from New-FFG” section establishes a baseline of the type and concentration of PFAS in FFG as it is received from the manufacturer.  Once in the field, PFAS on FFG may be a by-product from deterioration of the FFG or from the fire scene that has deposited on the FFG.  This section will describe exposing new-FFG to conditions that may mimic normal wear-and-tear conditions with the purpose of understanding to what extent these conditions cause the FFG itself to be a source of PFAS.

While in service, FFG may be exposed to varying levels of stresses, such as the following.

• Fire – elevated temperature, combustion products, direct flame impingement
• Mechanical – abrasion, snag, tear, bend
• Chemical – laundering, fire suppressants, AFFF, water, sweat, blood

Since the intent of the research in this section is to characterize PFAS generated from FFG, the stressing conditions will exclude fire scene elements which may be a source of PFAS (i.e., no exposure to combustions products or fire suppressants).   These elements will be included in the “Fire Scene and Used-FFG” section which is aimed at characterizing PFAS at the fire scene.  The stresses remaining that that are the most likely to result in additional release of PFAS are as follows. 

• elevated temperature
• abrasion
• laundering
• bending
• direct flame impingement

Based on preliminary discussions with subject matter experts, at this time, the top three stress may be the higher priority.

The elevated temperature stressing will occur in an oven held at 260 °C (typical elevated temperature exposure for testing of FFG).  During the stressing, gas samples will be collected.  The collection media and vessel will be washed using the same extraction solution used to extract FFG.  The extractate will be analyzed using LC-MS and GC-MS.  The PFAS on the stressed-FFG will be characterized using the same procedure described for new-FFG.  Rather than using an oven, an alternative approach to consider is to build a heating chamber that the GC can directly collect an aliquot for analysis.  After the test, the FFG would be extracted and the vessel washed out.  The solutions would be characterized by LC-MS. 

Abrasion stressing may be more of concern for the textile-based components of the FFG (i.e., bunker gear, hood and gloves).  Abrasion of these will occur following the procedure described in ASTM D1457.  PFAS characterization will involve LC-MS of the solution collected from extracting the stressed-FFG, abrading fabric, alcohol wipe sampling of the abrading tool, and any particulates released during abrasion.  Gas sampling will also occur throughout the test.  The wash from the gas collection vessel and media will be analyzed by LC-MS and GC-MS.

Laundering of the bunker gear, gloves, hood, etc. will follow the protocol described in NFPA 1851. PFAS characterization will involve LC-MS of the solution collected from extracting the FFG post stressing and laundering water.   I recommend working with other organizations, such as the National Personal Protective Technology Laboratory (NPPTL) who are already setup to and have extensive experience with laundering FFG. 

Task 3. Fire Scene and Used-FFG
The research in the previous sections establishes a baseline understanding of what PFAS may be present and generated from the FFG itself.  As a result of elevated temperatures up to and through complete combustion or extinguishment and overhaul, it is possible PFAS may be released or generated at a fire scene.  This may put FF at risk of being exposed to “fire scene” PFAS via inhalation while on the site, and digestion, inhalation or dermal absorption from PFAS deposited the FFG. There are at least two approaches to gain a better understanding of fire scene PFAS.

• Real Fire Scene: Partner with fire departments to collect air and surface wipe samples at real fire scenes (structural fires, AFFF locations, etc.).  FFGs analyzed from real fire scenes will be referred to as used-FFG.  FFG bound PFAS could be characterized from extraction of wipes taken of the FFG or of the FFG itself (if the FFG is replaced).  Gas sampling will also occur throughout the test.  The wash from the gas collection vessel and media will be analyzed by LC-MS and GC-MS.  While it is difficult to quantify how representative the results would be, working with fire departments at least gives real world information and could provide an avenue to data relevant to health risk exposure (e.g.; presence of PFAS in blood). 
• Simulated Fire Scene: Characterize PFAS collected from airborne and surface wipe sampling of compartment fires that are designed to mimic realistic environments, such as a family room.  FFG could also be placed in the room and later analyzed for PFAS (extraction and airborne).  If possible, one should collect and analyze samples both during and after the fire to mimic both an actual fire and overhaul scene. FFGs analyzed from simulated fire scenes will be referred to as simulated used-FFG.  Gas sampling will also occur throughout the test.  The wash from the gas collection vessel and media will be analyzed by LC-MS and GC-MS.

Task 4: Reducing FF’s risk of being exposed to PFAS from their gear
The risk of FFs being exposed to PFAS will be based on the type, concentration, and prevalence of PFAS found and released from FFG (Tasks 1-3).  Annually NIST will hold a PFAS-FFG workshop to share the results of this study and engage other parties in collaborating to advance PFAS-FFG related research.