Agent Orange Exposure Linked to Multiple Myeloma

Certain pesticide contaminants found to increase risk of multiple myeloma.

Multiple myeloma (MM) occurs in as many as 22,000 Americans annually. Evidence from a large, prospective population-based cancer screening trial illustrates the disease is steadily preceded by a precursor state, called monoclonal gammopathy of undetermined significance (MGUS).

The cause of MGUS and MM remain unclear, but existing evidence indicates that those working in farms and other agricultural industries face an increased risk of contracting the disease. More specifically, pesticides have been hypothesized as the basis for these associations.

A study recently aimed to expand the knowledge on the association between herbicides and MGUS through analyzing 958 serum samples obtained from US Air Force (USAF) personnel who conducted aerial herbicide spray missions of Agent Orange in the Vietnam War from 1962 to 1971 (Operation Ranch Hand).

The study focused on determining how many Operation Ranch Hand veterans showed evidence of MGUS compared with a control group to assess the risk of MGUS in relation to the body burden of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an Agent Orange contaminant that has been classified as a human carcinogen.

Using 958 stored serum samples from Ranch Hand veterans and comparison veterans, the study found the prevalence of MGUS in Ranch Hand veterans to be twice that of the control group.

These findings support prior research that certain pesticides play a role in the development of MGUS. Particularly in this study, the instance of MGUS increased with increasing body burden of TCDD.

Additionally, the MGUS prevalence was 2.43-fold higher in veterans who had TCDD levels greater than 10.92 parts per trillion (ppt) compared with veterans with TCDD levels of 3.65 ppt or lower.

“Our findings of increased MGUS risk among Ranch Hand veterans supports an association between Agent Orange exposure and multiple myeloma,” the study authors concluded.