Farming and mortality from non-Hodgkin's lymphoma: a case-control study

A case-control study of non-Hodgkin's lymphoma (NHL) and its subtypes among males was conducted using computerized mortality listings from the State of Wisconsin for the years 1968-1974. Age, year of death, race, county of usual residence, marital status, and usual occupation were abstracted for the 774 records of male deaths due to NHL and a matched series of deaths due to other causes. The frequency of farming occupation among NHL cases was compared to the frequency among controls, and odds ratios (OR) were calculated. Farming was more common among cases than among controls (OR = 1.22). The association of NHL with farming occupation was greater among decedents under 65 years of age (OR = 1.7) than among those who were older. The younger decedents were at higher risk of reticulum-cell sarcoma (OR = 2.7) than of other cell types. The strength of the association increased over the 9-year study period. County levels of selected agricultural characteristics were used as surrogate measures of farming exposures in residence counties of farmers and were summarized by factor analysis. Major findings were of elevated risk among younger farmers for reticulum-cell sarcoma in counties high in summary measures of general agricultural activity (OR = 3.2), of small grain acreage and acres treated with insecticides (OR = 6.6), and of wheat acreage (OR = 4.4). Given the limitations of the data, further investigation of non-Hodgkin's lymphoma in farmers is warranted.