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Climate-amplified wildland-urban interface disasters create persistent internal metal mixtures associated with pulmonary impairment

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This prospective cohort study (MauiWES) enrolled 1,400 adults from Maui, Hawaii 6 to 18 months after the August 2023 wildland-urban interface (WUI) wildfires that destroyed Lahaina. The study measured 24 urinary metals and assessed pulmonary function by standardized spirometry, enabling paired exposure-response analyses in a community-engaged Indigenous Hawaiian population. The WUI fires mobilized legacy contaminants from built infrastructure, generating metal exposure profiles beyond acute smoke inhalation.

Key numbers

  • n = 1,400 (final analytic sample after exclusions); spirometry quality grades A-C: FVC n = 790, FEV1 n = 790, FEV1/FVC n = 737, FEF25-75 n = 624.
  • Arsenic urinary concentrations in Lahaina (median 22.34 µg/L; IQR 9.83-55.40), substantially higher than Wailuku/Kahului (22.54 µg/L; IQR 10.58-65.05), p = 0.010.
  • MauiWES arsenic median 18.10 µg/L (IQR 7.73-48.39) versus NHANES 2011-2012 median 8.09 µg/L (IQR 3.89-18.62), p less than 0.001.
  • Antimony was 40-fold higher in MauiWES than in NHANES (1.97 vs. 0.05 µg/L, p less than 0.001).
  • In weighted quantile sum (WQS) models, each 1-quantile increase in the positive mixture index was associated with higher odds of FVC less than LLN (OR = 1.84; 95% CI: 1.37-2.45), FEV1 less than LLN (OR = 1.53; 95% CI: 1.07-2.17), FEV1/FVC less than LLN (OR = 1.83; 95% CI: 1.37-2.45), and FEF25-75 less than LLN (OR = 1.84; 95% CI: 1.33-2.56).
  • Arsenic, cadmium, copper, and antimony were the dominant positive contributors to the mixture impairment index; lead and nickel had the highest negative weights.
  • For arsenic as a single metal: arsenic was significantly associated with FVC less than LLN (OR = 1.26; 95% CI: 1.06-1.51); cadmium showed nearly a twofold increase in odds of FEF25-75 less than LLN (OR = 1.76; 95% CI: 1.11-2.76); FEV1/FVC less than LLN (OR = 2.20; 95% CI: 1.33-3.65).
  • Q-gComp models in Lahaina/Kula produced a significant association for FEF25-75 less than LLN (OR = 3.33; 95% CI: 1.27-8.72).

Methods (brief)

Urinary metals (24 analytes) measured by ICP-MS, normalized for specific gravity. Spirometry by ATS/ERS standards, grades A-C. Mixture analysis: dual-index WQS regression and Bayesian kernel machine regression (BKMR). Adjusted for age, sex, smoking status, BMI, and residential region. Pregnant participants excluded. Sensitivity analyses restricted to nonsmokers confirmed primary findings.

Evidence fitness

Supports: demonstrating that WUI disaster exposure creates persistent internal metal burdens (months after fire) associated with measurable pulmonary impairment; establishing arsenic and cadmium as the dominant metal contributors to mixture-associated lung function deficits. The arsenic signal is specifically from inhalation and environmental contamination, not diet. This is an inhalation-pathway study, not a dietary exposure study.

Limitations

Cross-sectional design 6-18 months post-fire; no pre-fire baseline spirometry; urinary metals do not distinguish inhalation from ingestion pathways; predominantly Native Hawaiian or Pacific Islander population (60%) may limit generalizability; exposure to wildfire ash, contaminated soil, and rebuilt infrastructure cannot be separated.

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