Pesticide use and non-Hodgkin's lymphoma mortality in Brazil

Brazil is one of the major pesticide consumers in the world. The continuous exposure to these substances may be etiologically associated with the development of Non-Hodgkin's Lymphoma (NHL).

Estimate the correlation between the per capita sales of pesticides in 1985 (exposure) and NHL mortality rates between 1996 and 2005 (outcome), by Brazilian micro-regions.

In this ecological descriptive study, the per capita consumption of pesticides in 1985 was used as a proxy of the population exposure to these chemicals in Brazil. All deaths by NHL occurred in the 446 non-urban micro-regions, between 1996 and 2005, among individuals with ages between 20 and 69, of both sexes, were retrieved from the Brazilian Mortality Information System. Micro-regions were then categorized into low, medium, high and very high pesticide consumption, according to the quartiles of per capita consumption of pesticides. NHL mortality rates and rate ratios for each quartile were obtained using the lowest quartile as reference. In addition, the Spearman's correlation coefficient between pesticide consumption and NHL mortality rates was estimated.

A moderate correlation between per capita pesticides consumption and standardized mortality rate for NHL was observed (r=0.597). In addition, using the lowest quartile of pesticide consumption as a reference, the higher the quartile of pesticide consumption, the higher was NHL mortality risk: men - (second quartile - MRR=1.69, CI 95% 1.68-1.84; third quartile - MRR=2.41, CI 95% 2.27-2.57; fourth quartile - MRR=2.92, CI 95% 2.74-3.11) and females (second quartile - MRR=1.87, CI 95% 1.69-2.06; third quartile - MRR=2.28, IC 95% 2.10-2.47; fourth quartile - MRR=3.20; CI 95% 2.98-3.43).

Our results suggest that pesticide exposure may play a role in the etiology of NHL.