The incidence of non-Hodgkin's lymphoma is increasing in many countries and is often related to environmental exposure factors. Many studies have tried to correlate exposure to certain agents or specific medical conditions with an increased risk for non-Hodgkin's lymphoma; however, few studies to date have evaluated the relationship between exposure to newer pesticides, herbicides and organic solvents with an increased risk for non-Hodgkin's lymphoma. Hardell and Eriksson assessed the risk for the development of non-Hodgkin's lymphoma after exposure to the newer pesticides.

Men over the age of 25 years who were registered at a regional cancer center in Sweden with confirmed non-Hodgkin's lymphoma were eligible for the study. Each patient was matched with two male control subjects of the same age and from the same area. An extensive questionnaire was mailed to all participants or their next of kin, specifically asking about use of pesticides, number of years of exposure, types of agents and cumulative exposure days. Data on smoking habits, previous diseases and food habits were also obtained.

A total of 404 patients with non-Hodgkin's lymphoma and 741 persons in the control group completed the questionnaire. Patients who were exposed to herbicides that contained phenoxyacetic acid, such as MCPA, were at a high risk for developing non-Hodgkin's lymphoma. Of note, however, was that the highest risks associated with this type of herbicide appeared to be when the first exposure was 10 to 20 years before diagnosis. Exposures to glyphosate, other herbicides, fungicides and glass wool were also associated with an increased risk for lymphoma. Exposure to insecticides or organic solvents did not increase the risk for lymphoma.

The authors conclude that the use of herbicides and other chemicals increases the risk for developing non-Hodgkin's lymphoma. Because glyphosate and other herbicides are commonly used, caution should be exercised and exposure limited when they are used. Further study of the relationship between exposure to glyphosate and the development of non-Hodgkin's lymphoma is warranted.