PFAS in the Blood of Maui Wildfire Responders, 2023

From CDC's Morbidity and Mortality Weekly Report*, "Notes from the Field" (corrected). By Catherine C. Beaucham, Rachel Zeiler, Kenneth Fent, Sophia K. Chiu, Nicholas Somerville, Alexander Mayer, Jessica L. Rinsky and Cheryl Estill, National Institute for Occupational Safety and Health (NIOSH), CDC.*

Summary

• Known before: PFAS (perfluoroalkyl and polyfluoroalkyl substances) — in some firefighting foams, fire smoke and dust, protective clothing and contaminated gear — put firefighters at risk and are linked to cancer, cholesterol changes and other harm.
• What this adds: about 1 month after the 2023 Maui wildfires, firefighters had higher combined PFAS levels than other county responders. Sources other than the fires may have contributed.
• What it means: more research is needed on wildfire responders' risk. Rostering responders, tracking their tasks and protective equipment, and monitoring health would help.

The fires and the request

Fire activity in the U.S. is rising, including destructive fires where wildland meets towns, exposing responders and communities to hazardous chemicals in air and debris. The August 2023 Maui wildfires destroyed thousands of structures, vehicles and parcels, and 102 people died. Firefighters, police, ocean safety officers and public works staff fought fires, protected structures, evacuated people and carried out water and urban search and rescue.

That August, Maui County asked NIOSH — through a FEMA mission assignment — to assess responders' chemical exposures. In September 2023, a NIOSH team and a CDC logistician went to Maui.

What was done

• Who: every county employee who worked the first 5 days (August 8–12, 2023) was invited.
• Samples: urine and blood, plus questionnaires; analyzed by CDC's National Center for Environmental Health.
• Why PFAS: they're expected where wildland meets urban areas and stay in the body a long time, so they can be detected weeks later.
• Comparisons: each PFAS against the 95th percentile for U.S. adults (NHANES, 2017–2018); the sum of seven PFAS against the National Academies' clinical threshold of 20 μg/L, above which doctors should prioritize screening for cancer and other effects (levels of 2–20 μg/L are linked to possible effects, especially in sensitive groups).

What was found

• 258 employees gave blood — 178 (69%) of them firefighters.
• PFHxS, one of the most persistent PFAS, differed by job (p<0.01) and was highest in firefighters: median 1.2 μg/L (IQR 0.8–1.7).
• The highest PFHxS, 9.3 μg/L, was a firefighter's — about 2.5 times the NHANES 95th percentile (3.8); everyone else ranged from undetectable to 3.8.
• For other PFAS, 2–40% of employees were above the 95th percentile.
• Summed PFAS: median 7.0 μg/L in firefighters, 5.7–6.9 in other groups. Only one person — the same firefighter — was over 20 μg/L, and was advised to see a doctor for further screening.
• Firefighters with 30 years or more on the job generally had higher levels, though several outliers had under 5 years.

Summed serum concentrations of seven PFAS (A) in all county employees by occupation, and (B) in firefighters by years of service. Boxes show the median and interquartile range; dots are outliers. CDC.

The responders: of 259 who answered the questionnaire, median age 40.0 (range 20.6–68.7), 94% male. They most often identified as White (54%), Asian (48%) or Native Hawaiian or other Pacific Islander (46%); 7% as American Indian or Alaska Native and 1% as Black (more than one could be chosen). Respirator use varied: about 40% of firefighters at active fires, 4–33% of other responders.

Firefighters were offered enrollment in the National Firefighter Registry for Cancer.

Conclusions

• Firefighters had higher levels of some PFAS than other workers, but nearly all were below the screening threshold.
• With samples taken a month later and no baseline, how much PFAS came from these fires is unclear; earlier studies already show firefighters carry more PFHxS than the general public.
• Inconsistent use of respirators and other protective gear could raise exposure.
• NIOSH published a full Health Hazard Evaluation in July 2024. Protecting responders means rostering them, tracking activities and equipment use, and monitoring health — for example through the Emergency Responder Health Monitoring and Surveillance framework.

Sources

Based on "Notes from the Field: Serum Concentrations of Perfluoroalkyl and Polyfluoroalkyl Substances Among First Responders to the Maui Wildfires — Hawaii, September 2023," MMWR, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The full evaluation: Somerville N, Beaucham CC, Mayer AC, Zeiler RJ, Estill CF, Fent K, HHE Report Nos. 2023-0136 and 2023-0142-3400 (NIOSH, 2024). The seven PFAS summed were PFHxS, PFOS, PFOA, PFNA, PFDA, PFUnDA and MeFOSAA.