Risk of Multiple Myeloma Doubles from Pesticide Exposure

Kathleen Blanchard's picture

Researchers have found that the risk of a rare blood disorder that can lead to multiple myeloma doubles from exposure to certain pesticides commonly used in agriculture, putting farmers especially at risk. MGUS (monoclonal gammopathy of undetermined significance), is found to precede multiple myeloma, a painful bone marrow cancer that is often found among farmers. The study also has health implications for the general population.

Lead author Ola Landgren, MD, PhD, of the National Cancer Institute (NCI) says, “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."

The authors note that past studies link agricultural work to multiple myeloma, but the association has been unclear. The widespread use of pesticides among millions of Americans has significant health implications.


The study included 678 individuals who apply pesticides, extracted from a U.S. Agricultural Health Study of over 50,000 farmers, comparing levels of MGUS to the normal population. The individuals ranged in age from 30 to 94, and all lived in North Carolina and Iowa. Questionnaires were used to establish risk of pesticide exposure and included use of protection, amount of pesticide use, application methods, and years of use. Family history of cancer, other potential risk of multiple myeloma, including alcohol and smoking, and other lifestyle factors were included in the study.

The results were compared to 9,469 men living in Olmsted County, Minnesota who were part of the general population. No women were involved in the study. The researchers found that the risk of MGUS, that leads to multiple myeloma increased with age in the study group exposed to pesticides, increasing by 6.8 percent after age 50. The overall risk of MGUS was 1.9 percent, compared to the general population.

Dr. Landgren suggests the need for research to uncover the molecular basis of how MGUS leads to multiple myeloma. The current study shows that the risk of multiple myeloma doubles from exposure to pesticides, which may be especially important for anyone involved in agricultural work, as well as the rest of the Western World.

American Society of Hematology