Pesticides and Non-Hodgkin Lymphoma

Young man spraying pesticide in plant nursery.

Non-Hodgkin’s lymphoma, the group of blood cancers that accounts for nearly 90 percent of all lymphomas, has many types and subtypes. The cells involved are lymphocytes, a type of white blood cell.

Rates for new cases of non-Hodgkin lymphoma, or NHL, doubled from the 1960s to the 1990s, leading people to wonder about the possible causes. It’s a question that has driven a lot of research, including investigation of pesticides.

NHL is not one disease but many related diseases, potentially with variably important causes for each type, which complicates the study of risk factors like exposure to pesticides.

Is there no Smoking Gun?

Pesticides – and phenoxy acid herbicides in particular -- have been suggested as a cause of NHL, but the evidence has been inconsistent. An example of a phenoxy acid herbicide is the agent 2,4-D. Few studies of pesticides have been large enough to evaluate the potential link between NHL subtypes and specific pesticide exposures, according to research published in the March/April 2013 “CA: A Cancer Journal for Clinicians.”

Many different agricultural chemicals have been associated with NHL in some studies. Often, however, there are other studies showing no such link. If a particular agent has an obvious connection to cancer that can be quickly and easily detected, it is less likely that it would have been approved to enter the market.

So it is challenging to find a smoking gun, although it's clear that science evolves and historically, harmful substances have gone unrecognized for a long time.

Which Compounds Are Being Studied?

According to research published in the April 2014 issue of “International Journal of Environmental Research and Public Health,” a whole variety of herbicides and insecticides have been studied, and a number of agents have been positively associated with NHL, include the following:

  • Phenoxy herbicides like 2,4-D
  • Carbamate insecticides like Carbaryl, or Sevin
  • Organophosphorus insecticides like malathion
  • The organochlorine insecticide, Lindane
  • Glyphosate, like in Roundup and other brands of weed killer

Finding an association is not the same as finding a cause, however. It's just the beginning of trying to figure out what could possibly be going on.

Studies finding an association, above, were done in the United States, Canada, Europe, Australia and New Zealand, and scientists say a larger variety of pesticides in more geographic areas, especially in other countries, would be beneficial -- since a large portion of the world’s produce comes from these areas.

Researchers also pointed out that, especially for people who work in agricultural production, the wide variety of exposures to chemicals, bacteria, and other agents simultaneously makes sorting things out a huge challenge.

What is the Risk to Farmers and Agricultural Workers?

Farming and pesticide use have previously been linked NHL and other blood cancers.

One recent study looked at 52,394 private pesticide applicators, mostly farmers in Iowa and North Carolina and 4,916 commercial applicators in Iowa -- people who apply pesticides to farms, homes, lawns, etc.

According to this research, which was published in the October 2014 edition of “PLoS One,” different kinds of pesticides from different “chemical families” were associated with an excess risk of NHL and NHL subtypes; but not all members of any single chemical family of pesticides were associated with that increased risk. Researchers said that their study, which looked at people who work with pesticides, is among the first of its kind to suggest links between DDT, lindane, permethrin, diazinon and terbufos and specific NHL subtypes.

They concluded that the following links, in particular, deserved further evaluation:

  • Links between DDT and terbufos and: small B-cell lymphocytic lymphomas, chronic B-cell lymphocytic lymphomas, mantle-cell lymphomas.
  • Links between lindane and diazinon and follicular lymphoma.
  • Links between permethrin and multiple myeloma.


Types of Pesticide Ingredients. Accessed April 2015.

Non-Hodgkin Lymphoma and Occupational Exposure to Agricultural Pesticide Chemical Groups and Active Ingredients: A Systematic Review and Meta-Analysis Accessed April 2015.

Prolonged exposure to certain pesticides and detergents increase the risk of lymphoma. Accessed April 2015.

Alavanja M, Ross M, Bonner M. Increased cancer burden among pesticide applicators and others due to pesticide exposure. CA Cancer J Clin. 2013;63(2):120-142.

Alavanja MCR, Hofmann JN, Lynch CF, et al. Non-Hodgkin Lymphoma Risk and Insecticide, Fungicide and Fumigant Use in the Agricultural Health Study. Akiba S, ed. PLoS ONE. 2014;9(10):e109332. doi:10.1371/journal.pone.0109332.

Dich J, Zahm SH, Hanberg A, Adami HO. Pesticides and cancer. Cancer Causes Control. 1997; 8: 420-443.

Updated November 2015. T.I.

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