International charity Oxfam America and the Mississippi NAACP on Wednesday called for an independent contractor to test FEMA trailers for elevated formaldehyde emissions.

The Federal Emergency Management Agency, acting on dozens of complaints from Mississippi residents living in its trailers, has said the Environmental Protection Agency will conduct air quality tests on the housing.

But state NAACP President Derrick Johnson said FEMA has not acted aggressively enough to address formaldehyde concerns that have been circulating since spring.

"The government has a duty to provide a safe environment for the victims of the hurricane and the children to live in, and apparently that has not been done," Johnson said.

FEMA provided more than 118,000 trailers to victims of Hurricane Katrina and Hurricane Rita — primarily in Mississippi and Louisiana — who lost their homes in the storm.

The agency has received 46 complaints from people in Mississippi who claim they have had health problems since moving into FEMA trailers. In May, the state's Sierra Club chapter issued a nonscientific report of its own testing which found high formaldehyde emissions in dozens of trailers in Mississippi and Louisiana.

Formaldehyde is used in manufacturing, as a preservative in some foods and in household products. It can irritate the skin, eyes, nose and throat. High levels of exposure may cause some types of cancers.

FEMA spokesman Aaron Walker said Wednesday that the agency has no plans to go outside the federal government to conduct tests. "We're confident in our trailer program and the testing comes out of an abundance of caution to make sure our residents are comfortable," he said.

Minor Sinclair, U.S. regional director of Oxfam America, a nonprofit international development organization assisting in the Gulf Coast recovery, said independent testing would ensure public accountability and transparency and could even speed the process.

"If the government takes so long to get the trailers into place, how much longer will it take to inspect them?" Sinclair said.