Harvard Public Health Review
Mold, Mold, Everywhere
Scientists see no precedent for the potential hazard in New Orleans.
Scientists see no precedent for the potential hazards in New Orleans. Mold has attacked what remains of New Orleans, engulfing the city in slime.
Typically, clean indoor environments show mold spore concentrations of less than 1,000 per cubic meter of air. But in Katrina's wake, the numbers have hit several million due to widespread, persistent flooding.
That's the preliminary report from Christine Rogers, a senior research scientist in the Department of Environmental Health at HSPH. In September, Rogers led a hands-on investigation of mold contamination so extensive that the health hazards are unknown. "Our fear was that city residents returning home might experience massive exposures, simply by retrieving belongings and doing minor clean ups," she says.
Tapped by the National Institute of Environmental Health Sciences (NIEHS) Center at Harvard to come up with recommendations as part of a national NIEHS working group, Rogers had searched the literature. But she could find no data applicable to the situation in New Orleans, where water has stood motionless in closed-up buildings, several feet deep, for weeks.
Symptoms of mold sensitivity range from flu-like symptoms to shortness of breath to skin irritations, Rogers says. People at elevated risk include anyone with allergies or breathing problems. Those who are immunosuppressed--on cancer chemotherapy, for example, or have HIV/AIDS--are at especially high risk for fungal infections in the lungs.
High mold levels can change a person's immune status. "Once you generate antibodies, subsequent exposures can elicit symptoms," Rogers explains. In asthma, attacks can become life-threatening; lung inflammation can also set in. "But even your average person is at risk for symptoms at this level of exposure," she notes. "Anyone who is genetically predisposed can develop mold allergies down the road."
As New Orleans residents began trickling back home, Rogers set to work. With her were HSPH research associate Michael Muilenberg; Ginger Chew, an assistant professor at Columbia's Mailman School of Public Health; and Tanya Santiago and Rob Maestretti, students from the Tulane School of Public Health and Tropical Medicine who had fled Louisiana for a semester at HSPH. Using Maestretti's dry apartment as a base, the team roamed the streets for three days, obtaining consent to explore sodden homes.
What they found amazed them: Wall-to-wall mold colonies. "It was biological warfare, with all these fungi fighting for space," Rogers says.
Colors ran riot--corals, pinks, rusty browns, powdery whites, including fungi they'd never seen before. (Of an estimated 1.5 million species of mold, only 70,000 or so have been characterized.) Familiar types included blue-green Penicillium, one species of which is the well known antibiotic; Aspergillus, ranging from blacks to greens to orange; and surprisingly few colonies of Stachybotrys, a.k.a. "black toxic mold."
Team members distributed "mold kits" to residents: rubber gloves, N95 respirators resembling surgical masks, and a sheet of health warnings and clean-up instructions. Bleach can be used to kill mold spores; however, spores must not merely be killed, but also removed, since allergens and toxins remain. Furnishings, dry wall, and floorboards must be discarded.
Outdoor air quality is also a concern. Given an estimated 22 million tons of mold-contaminated debris, there is "no such thing as fresh air," Rogers says.
Thanks in part to the HSPH team's effort--and with an assist from Harvard NIEHS Center Director Joseph Brain, HSPH Cecil K. and Philip Drinker Professor of Environmental Physiology--30,000 respirators are now being distributed through the Red Cross. In the near future, Rogers will expand her research, correlating spore concentrations with New Orleans residents' health status.
For details on mold management, see the Environmental Protection Agency website at http://www.epa.gov/mold/ moldresources.html.
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