By Maggie Fox, Health and Science Editor
WASHINGTON (Reuters) - Pressed wood products such as particle board are the main source of irritating formaldehyde fumes in trailers used to house disaster victims, according to a U.S. government report to be released on Wednesday.
Such temporary housing should be designed with better ventilation, the report from the U.S. Centers for Disease Control and Prevention suggests, and current health and safety standards may not be enough to protect people.
"Even though construction materials meet standards ... you have to be a little bit careful about how you use those construction materials. You could end up fostering high levels of formaldehyde," said CDC spokesman Glen Nowak in a telephone interview.
Tens of thousands of people displaced by hurricanes Katrina and Rita along the U.S. Gulf Coast in 2005 are still living in such trailers, and the Federal Emergency Management Agency is sending hundreds to people displaced by Midwestern flooding.
The CDC contracted with the Lawrence Berkeley National Laboratory in California to cut open several trailers and measure concentrations of formaldehyde and other irritating chemicals known as volatile organic compounds.
"We refer to it internally as the chain saw study," Nowak said. "We went beyond formaldehyde and looked at levels of other volatile organic compounds.
"Were there certain parts of the trailer -- walls, ceiling, floors, cabinets -- that made a greater contribution to the levels of formaldehyde in these trailers?"
Unsurprisingly, they found that processed wood products such as particleboard and plywood were the main source of formaldehyde. They did not find other chemicals at significant levels.
Formaldehyde, used to manufacture many building materials, can irritate the skin, eyes, nose and throat. High exposure levels may cause cancer.
The Department of Housing and Urban Development identified particleboard and plywood as one of the largest sources of formaldehyde emissions in 1985 and set standards for manufactured homes to limit them.
Nowak said all the relevant agencies would meet to discuss what to do.
"It has implications for FEMA as FEMA looks at emergency housing. One of the factors they need to consider is indoor air quality and the construction materials used in the ventilation systems," Nowak said.
An earlier CDC study showed average levels of formaldehyde in trailers and mobile homes was about 77 parts per billion (ppb) -- a level high enough to raise the odds of cancer and respiratory diseases.
Michael McGeehin, director of the Division of Environmental Health Hazards at CDC, said the findings only applied to trailers distributed by FEMA in the Gulf Coast Region.
"However, taken together, the two studies indicate that 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," McGeehin said in a statement.
(Editing by Alan Elsner and Will Dunham)