High levels of formaldehyde found in trailers provided to Hurricane Katrina evacuees on the Gulf Coast probably resulted from cheap wood and poor ventilation in designs used by manufacturers under permissive government standards, federal scientists reported yesterday.
An analysis by researchers for Lawrence Berkeley National Laboratory found that four Katrina trailers emitted the toxic chemical at levels four to 11 times as high as those found in typical U.S. homes. The study looked at both commercially available units and ones custom-built for the Federal Emergency Management Agency in 2005 and 2006.
The new findings appear to confirm the role that manufacturers' practices and weak federal regulation played in the public health disaster after the August 2005 storm. The House Committee on Oversight and Government Reform has called trailermakers to testify Wednesday.
"Manufacturers of travel trailers and the government agencies that influence their design should consider using construction materials that emit lower levels of formaldehyde as well as designs that increase outside air ventilation," said Michael McGeehin, director of the Division of Environmental Health Hazards at the U.S. Centers for Disease Control and Prevention, which commissioned the study.
Formaldehyde, an industrial chemical used in adhesives found in wood products, can cause nasal cancer and worsens asthma and other respiratory problems. There is no binding safety standard for the chemical in U.S. homes. Under a 23-year-old rule, the government limits formaldehyde emitted by wood products only in mobile homes, which typically sit on concrete pads, not in wheeled trailers or other housing. It also does not restrict how much of that wood can be used.
Berkeley researchers said they found "exceptionally large emissions of formaldehyde" in units tested and traced the chemical's presence to extensive use of cheap, light plywood and particleboard for walls, flooring and cabinet surfaces. At the same time, trailers "are not outfitted for adequate ventilation and are tighter than would be desired for housing with such small volume," they said.
Formaldehyde was "found to be higher, sometimes much higher, than what is typically found in residential environments," they wrote. "The combination of these factors is likely to be the cause."
The CDC recommended this year that all FEMA trailer residents be moved to safer housing. The agency found that 42 percent of trailers tested in December and January had levels of formaldehyde higher than those for which it recommends a 15-minute exposure limit for workers. Residents probably experienced higher levels when trailers were new and during warm weather, the CDC said.
FEMA received 11,000 health complaints and moved more than 4,000 families. About 19,000 Katrina units remain occupied, down from about 143,000.
Spencer S. Hsu
July 3, 2008