Pesticide Exposure Linked to Multiple Myeloma Precursor

A study of farmers found that exposure to certain pesticides was associated with the development of monoclonal gammopathy of undetermined significance (MGUS), a precursor to multiple myeloma (MM).

Previous studies have shown that farmers have a higher incidence of MM and MGUS compared with the general population. Pesticide exposure is a suspected factor in the development of MGUS, but there are limited data on this association. Researchers from the National Cancer Institute and other health systems designed this study to evaluate the prevalence of MGUS in farmers and to evaluate any relationships between disease development and a variety of pesticides.

Data were collected from the Agricultural Health Study (AHS), a prospective cohort of farmers from Iowa and North Carolina. A total of 1,638 male participants who were at least 50 years old were included. The investigators estimated odds ratios (ORs) for associations with MGUS for recent (within 12 months) and cumulative lifetime use of specific pesticides.

The prevalence of MGUS was significantly higher among the AHS cohort (7.7%) when compared with demographically similar men in the National Health and Nutrition Examination Survey (2.8%) or a comparison cohort in Olmstead County, Minnesota (3.8%, P<0.001). Recent use of the pesticide permethrin was associated with MGUS development (recent use vs. no recent use, OR, 1.82; 95% confidence interval [CI], 1.06-3.13). This association was elevated for individuals who had used the pesticide in the past (recent and past use vs. never use, OR, 2.49; 95% CI, 1.32-4.69).

High intensity lifetime use of the organochlorine insecticides aldrin and dieldrin was also linked with increased rate of MGUS compared with those who never used either (OR, 2.42; 95% CI, 1.29-4.54; P<0.006). Similar associations were also identified for individuals with lifetime use of petroleum oil/distillates as an herbicide.

This is the largest investigation of MGUS in farmers and the first to identify an association with MGUS for permethrin, a pyrethroid insecticide previously associated with MM. Given the continued widespread use of permethrin in various residential and commercial settings, our findings may have important implications for exposed individuals in the general population,” the researchers concluded.

This study was published in Environmental Health Perspectives.