The University of Hawaiʻi at Mānoa Maui Wildfire Exposure Study tracked the urine of 1,400 Maui adults 6 to 18 months after the August 2023 wildfire, finding that the concentration of metals in some participants was substantially higher than those on the continental U.S.
Fires can burn homes, vehicles, and electrical systems that can create toxic contaminated mixtures that last long after the fire is put out, and the contaminants can remain in ash, dust, soil and debris and be transferred during cleanup and recovery.
Alika Maunakea, the MauiWES co-director and a professor at the UH John A. Burns School of Medicine, said that wildfire exposure is often thought of through smoke inhalation and exposure, but this study helped broaden the lens of possible health implications.
“Our study suggests that months after the fires, many residents were still carrying elevated mixtures of metals in their bodies, meaning that exposure did not necessarily end when the smoke cleared,” Maunakea said. “Lahaina showed some of the strongest exposures, but we also found different patterns of elevated metals and lung impairment across Wailuku, Kahului, Kīhei, and Kula at different degrees. That tells us that the health footprint of a disaster like this can extend beyond the places where the buildings actually burned.”
The most prevalent metals found were arsenic, cadmium, copper and antimony, which was found in Maui residents at nearly 40 times the concentration of those across the continental U.S.
Researchers said this isn’t solely tied to the Lahaina wildfire, stating that the results seem to link to multiple events rather than a one-time exposure.
Things like geology, agriculture, diet and other environmental factors can all play a role in the concentration of metals. They were unable to detect how much the levels of metals increased due to the fire since there was no pre-fire data collected.
Ruben Juarez, a MauiWES co-director, said there were also ties found to abnormal lung function.
“The people with higher combined metal exposure were consistently more likely to have abnormal lung function tests, and importantly, it was not one metal,” Juarez said. “We cannot rely only on short-term air monitoring and assume the danger is over once the smoke disappears. Communities may need long-term monitoring, respiratory screening, and environmental cleanup to understand and reduce exposures that can continue for months or even longer after a disaster.”
