Arsenic and old sugarcane: cleaning up Hawaii in the fallout from wildfires

When fire engulfed Lahaina last year, some of the older structures that burned contained canec, a historic Hawaiian -made building material made of solid sugarcane waste and potentially harmful inorganic arsenic.

To date, the US army corps of engineers (USACE) has hauled off an estimated 14,000 tons of ash suspected of arsenic contamination from the drywall-like material once manufactured in Hilo.

From the 1930s to the mid-1960s, the Hawaiian Cane Products company produced canec, which was often used for ceilings and walls in homes and other properties around the islands. The company billed the material as perfect for the modern home and used bagasse, the dry rinds of sugarcane stalks after they had been crushed for the juice that becomes sugar. Since sugarcane was grown and processed in Hawaii since the 1850s, the company exploited a readily available and abundant natural resource; a dozen sugarcane plantations sent the stalks to the plant. Bagasse has also fed sugar mills’ operations, local power grids and has even become an eco-friendly component in compostable food-service packaging and paper.

But canec had a notable disadvantage: extreme susceptibility to termites . The company treated it with arsenic to deter pests.

According to a Hawaii state department of health factsheet, canec typically doesn’t pose a health problem if it is in good condition, not “rotting” or “powdering away”. But if canec is damaged, it can release inorganic arsenic particles in its dust or debris (arsenic occurs naturally in the earth, but its inorganic form is highly toxic). Long-term inhalation or ingestion can cause poisoning and is linked to skin disorders, certain cancers and various problems in pregnancy and child health, according to the World Health Organization.

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The wildfire that swept west Maui was precisely the kind of event that could pulverize canec and transform it into a public-health concern. It’s become one component of the toxic cocktail that comes with massive disaster, as household cleaners, propane and other fuels, asbestos and mold can contaminate the environment and living spaces.

Tests of wildfire ash have found high levels of arsenic and other metals in sites around Lahaina. A March email from an army corps of engineers representative wrote that “canec was a commonly used building material within the impacted area of Lahaina”.

But that spokesperson added it was difficult to define the scope of the problem because the corps didn’t have permission to enter many private homes. Since then, the USACE got the approval of more than 150 homes, and the agency completed canec removal for those structures. According to an August update, debris removal is pending for 11 commercial sites suspected to contain canec. Ash containing residual arsenic from burned canec is wrapped in plastic during transport in plastic-lined trucks to a temporary debris storage site .

But should local residents worry? USACE is responsible for removing fire debris and testing excavated areas to ensure they meet state health department requirements to allow property owners to rebuild. However, its mission does not include long-term testing or monitoring, though the Hawaii health department continues to analyze samples of air, ash, soil, sediments, beach sand and nearshore water; it recently set up a portal for the public to track levels of contaminants .

There’s some precedent for long-term contamination. The canec plant had discharged millions of gallons per day of wastewater into an area pond for decades. According to a 2005 report , sediments in nearby Hilo Harbor had the highest concentrations of arsenic of anywhere else in the state by 1978 – due to a variety of factors, including pesticide use. But levels in water were relatively low, probably because inorganic arsenic is not very soluble. Still, there was a cleanup of the area around the plant as recently as 2018.

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David Herndon, a former navy environmental health officer, has been deeply involved in hazardous waste cleanup on military bases, including updating West Point’s hazardous waste management program. Once stationed in Hawaii, he is familiar with canec and previous cleanups, though he is not involved with the Lahaina efforts. He noted that data showed arsenic contamination at the canec plant was highest at surface level, and that type contamination can easily be treated before removal to keep the arsenic from dispersing to nearby sites.

“Canec should be treated like asbestos for disposal and removal purposes,” said Herndon. “It poses minimal health risk if mandated [personal protective equipment] is worn by everyone in the affected area and the bagging of the material is done as directed by environmental agencies” such as the Environmental Protection Agency (EPA) or Occupational Safety and Health Administration (Osha).

He continued: “I would live on a site that has been cleaned and soil tested after, as is required by the EPA.” Exposure can be minimized by moistening the arsenic-contaminated soil or building materials before they are handled and removed. Containing the dust also lessens the chances of contaminating groundwater and down-wind sites.

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Oralani Koa acts as a liaison between federal contractors working on cleanup (including USACE and the Federal Emergency Management Agency, or Fema) and the community. She also works in the hotel industry and said the current phase of recovery entails “finding balance between housing and tourism. That’s where the temperature of the community is at.” Amid a pre-existing housing crisis that’s only deepened since the Lahaina tragedy, many of her neighbors are far more concerned with where future housing will be built – as sea levels rise and water resources dwindle – than toxic waste like canec.

Still, canec isn’t entirely removed from tourism and development in Maui. In 1971, builders constructed apartments and condos on the former Hawaiian Cane Products plant, which had also burned to the ground. Those properties continue to welcome Airbnb guests and homebuyers to this day.