Morticians who use formaldehyde to embalm bodies have a higher risk of leukemia, researchers reported on Friday.

They found deaths from one particular kind of leukemia, myeloid leukemia, increased the longer the workers were involved with embalming.

Their study of more than 400 funeral workers is the first to look carefully at the association, they reported in the Journal of the National Cancer Institute.

"Previous studies have shown excess mortality from lymphohematopoietic malignancies and brain cancer in anatomists, pathologists, and funeral industry workers, all of whom may have worked with formaldehyde," Laura Freeman of the U.S. National Cancer Institute and colleagues wrote.

They studied 168 professionals who died of various forms of leukemia, 48 who died of brain tumors and compared them to 265 funeral workers who died of something else.

The people who spent more years embalming bodies or were otherwise exposed to embalming fluid were more likely to have died from a myeloid leukemia, the researchers found.

"In recent decades, more than 2 million U.S. workers are exposed to formaldehyde, including anatomists, pathologists, and professionals who are employed in the funeral industry and who handle bodies or biological specimens preserved with formaldehyde," they wrote.

Their study could help explain a known higher risk of death among these professionals, they said.