EPA/John Messina
After reviewing nearly 30 years’ worth of data, investigators have compiled a list of agricultural chemicals that appear to increase a person’s risk of developing non-Hodgkin lymphoma (NHL).
Meta-analyses suggested that occupational exposure to phenoxy herbicides, carbamate insecticides, organochlorine insecticides, and organophosphorus insecticides/herbicides can increase the risk of NHL.
The research also revealed associations between certain chemicals and specific NHL subtypes.
Leah Schinasi, PhD, and Maria E. Leon, PhD, of the International Agency for Research on Cancer in Lyon, France, described the analysis and its results in the International Journal of Environmental Research and Public Health.
The investigators reviewed epidemiological research spanning nearly 30 years and identified 44 relevant papers. The papers recounted studies conducted in the US, Canada, Europe, Australia, and New Zealand.
Drs Schinasi and Leon used these data to assess occupational exposure to 80 active ingredients and 21 chemical groups and clarify their role in the development of NHL. Most, but not all, of the studies looked at lifetime exposure to the chemicals in question.
The investigators performed a meta-analysis of the data and found associations between NHL and a range of insecticides and herbicides. But the strongest risk ratios (RRs) were for subtypes of NHL.
There was a positive association between exposure to the organophosphorus herbicide glyphosate and any NHL (RR=1.5), but the link was stronger for B-cell lymphoma in particular (RR=2.0).
Phenoxy herbicide exposure was associated with an increased risk of NHL in general (RR=1.4), B-cell lymphoma (RR=1.8), lymphocytic lymphoma (RR=1.8), and diffuse large B-cell lymphoma (RR=2.0). As for specific phenoxy herbicides, both MCPA (RR=1.5) and 2,4-D (RR=1.4) were associated with NHL.
Carbamate insecticides, as a group, appeared to confer an increased risk of NHL (RR=1.7). The individual insecticides carbaryl and carbofuran showed positive associations with NHL as well (RRs of 1.7 and 1.6, respectively).
There was a positive association with NHL for organophosphorus insecticides as a group (RR=1.6), as well as the individual insecticides chlorpyrifos (RR=1.6), diazinon (RR=1.6), dimethoate (RR=1.4), and malathion (RR=1.8).
Lastly, organochlorine insecticides appeared to confer an increased risk of NHL (RR=1.3). DDT was associated with NHL (RR=1.3), B-cell lymphoma (RR=1.4), diffuse large B-cell lymphoma (RR=1.2), and follicular lymphoma (RR=1.5). And lindane was associated with NHL in general (RR=1.6).
The investigators said this analysis represents one of the most comprehensive reviews on the topic of occupational exposure to agricultural chemicals in the scientific literature.
But it also suggests a need to study a wider variety of chemicals in more geographic areas, especially in low- and middle-income countries, as they were missing from the literature.
