History of high household pesticide use and Parkinson's disease in Brazil

Towards a methodological uniformization of environmental risk studies in Parkinson’s disease

“…Other questionnaire-based studies also explored this association. Analyzing people living in a developing country (Brazil), we described that high exposure to household pesticides (defined as >30 days per year) was associated with higher odds of developing PD (adjusted odds ratio = 2.27, 95% confidence interval 1.46-3.52) in a total sample of 936 participants 2 . Considering that synthetic pyrethroid insecticides are the main household pesticides globally used for pest control of mosquito-borne diseases, the rational use of these chemical products might reduce the number of new PD cases.…”

“… < 0.001 2.85 35% 23% (12-34%) Moura et al . 2 All participants 562 374 539 356 2.27 1.46-3.52 < 0.001 2.27 18% 10% (5-12%) Males 293 165 282 156 2.19 1.18-4.04 0.012 2.19 20% 10% (3-15%) Females 269 209 257 200 2.43 1.28-4.6 0.006 2.43 16% 9% (3-12%) Narayan et al . 4 All participants 357 807 357 807 1.37 1.13-1.92 Not described 1.37 34% 9% (3-16%) Household pesticide exposure was tested for association with PD through a multivariate logistic regression analysis (described in the original studies), followed by PAF calculation for exposure.…”

“…Regarding the methods of measurement of pesticide exposure, each of these three studies applied distinct questionnaires, with merits and flaws. For example, the analyses of Moura et al used data from a short questionnaire proposed by the Latin American Research consortium on the GEnetics of Parkinson’s Disease (LARGE-PD) which did not distinguish among different pesticide chemical classes and age categories but included a high-tier frequency category of high threshold (use >30 days per year) 2 . Payami et al used a questionnaire with no discrimination of household or occupational pesticide use or distinct exposure to herbicides, insecticides, and fungicides, and defined categories of frequency of use 1 .…”

“…The definition of high pesticide exposure was variable among these studies. Moura et al arbitrarily considered each participant who used pesticides >30 days per year as high exposure 2 . Payami et al asked people if they had been “ever exposed to heavy uses of pesticides or herbicides”, without a clear definition of “heavy use” 1 .…”

“…The selection of covariates used for adjusting in multivariate models for the association studies of pesticide exposure and the onset of PD is essential for the goodness-of-fit. For example, lifetime smoking, a protective factor for PD onset, is a common covariate included in the multivariate regression model of these studies 2 , 4 . Thus, we propose the inclusion of relevant covariates for the onset of PD (sex, age at evaluation/onset, origin, smoking, education, family history, polygenic risk score) for these models.…”