Agricultural toxic use and temporal distribution of male birth rate in the state of Paraná, Brazil

To determine the trend in male birth rates from 1994-2004 in the state of Paraná, Brazil, and whether a correlation exists between this trend and the state's agricultural toxic sales in 1985. This ecological study employed data from the Brazilian Institute for Geography and Statistics (agricultural toxic sales) and the Unified Health System's database "DATASUS" (sex ratio at birth). Three hundred and eight (308) municipalities were analyzed, divided into quartiles by pesticide usage. Each of the four resulting quartiles included 77 municipalities, with the fourth quartile representing the highest consumption. The male birth rate was obtained for each year for each municipality. Then the median rate was calculated for the entire period (1994-2004) for each municipality. A bivariate analysis was carried out. Pearson coefficients were calculated for each quartile. An exploratory and comparative analysis of quartiles was performed, and the mean per capita consumption was calculated for each quartile. Ten municipalities with intense agricultural activity were then selected and analyzed individually in terms of their agricultural profile and male birth rate trend during the study period. A discrete decline was observed in the rate of live male births for the entire state. The magnitude of this decline was more evident when the group of 10 municipalities was analyzed: in this group, the rates observed at the end of the study period were much lower than those usually described in the literature (male birth rate < 50%). Pearson's correlation was negative for all quartiles, although without statistical significance. The statistically significant trend towards a decline in male births in some of the Paraná municipalities suggests that this phenomenon may be a result of a high level of environmental exposure to pesticides. Future studies should confirm and measure the impact of environmental pesticide contamination on reproductive health, expressed in this study as sex ratio at birth.