THURSDAY, June 18, 2009 (HealthDay News) -- People who apply pesticides have double the normal risk of developing a precancerous blood disorder, say U.S. researchers.
Called MGUS (monoclonal gammopathy of undetermined significance) and characterized by an abnormal level of plasma protein, the disorder requires lifelong monitoring because it can lead to multiple myeloma, a cancer of the plasma cells in the bone marrow.
The study looked at 678 men, aged 30 to 94, in North Carolina and Iowa who apply pesticides and compared them to more than 9,000 men from the general population in Olmsted County, Minn.
No cases of MGUS were found among those younger than 50 in the pesticide-exposed group, but the rate of MGUS in those older than 50 was 6.8 percent. That was 1.9 times higher than among the men in the general population group.
The researchers also identified risk levels associated with specific types of pesticides. They found the risk of MGUS was 5.6 times higher for those who used an insecticide called dieldrin; 3.9 times higher for those who used the fumigant mixture carbon-tetrachloride/carbon disulfide, and 2.4 times higher for those who used a fungicide called chlorothalonil.
The study appears in the June 18 issue of the journal Blood.
"Previously, inconclusive evidence has linked agricultural work to an increased multiple myeloma risk. Our study is the first to show an association between pesticide exposure and an excess prevalence of MGUS," study author Dr. Ola Landgren, of the U.S. National Cancer Institute, said in a news release.
"This finding is particularly important given that we recently found in a large prospective cancer screening study that virtually all multiple myeloma patients experienced a MGUS state prior to developing myeloma," Landgren added.
The U.S. National Institute of Environmental Health Sciences has more about pesticides.