Prolonged daily high-dose exposures during active spraying coupled with the long-term chronicity of exposure have been documented to contribute to lymphoma risk. The causal relationship is particularly strongly recognized in individuals who work in agricultural settings where extremely high-level exposures are common compared to residential exposure use. It is in this setting that the most compelling epidemiologic evidence has emerged for cancer risk from exposure this chemical. While farm workers are traditionally at long-term higher risk due to occupational exposures, they are typically trained in the routine use of personal protective equipment including masks, gloves, and clothing designed to limit personal exposures. In this context, agricultural work and certain associated chemical exposures have been documented to place workers at increased risk for NHL and other malignancies.
Environmental/chemical exposures are typically associated with the development of malignancies due to two factors-dose of exposure and duration of exposure. Like many malignancies, lymphomas are now recognized to have a long premalignant phase before evolution to frank clinical lymphoma. Malignancies that follow this pattern result from many genetic mutations over time and prolonged or recurrent exposures to causative agents are common features. Similarly, there are multiple studies indicating a specific increase in risk of CLL associated with farming and pesticide/Roundup exposure. Pesticides, including herbicides, insecticides, fungicides, and rodenticides have important public health benefits. However, they are designed to impact living systems so unintended health effects are to be expected. Although exposure levels are highest in people actively using these chemicals, others may be affected by various forms of spread. Persistent pesticides or their metabolites can be found at low levels in biological tissues of most individuals throughout the world.