Parkinson's Disease Prevalence and Proximity to Agricultural Cultivated Fields

Abstract

The risk for developing Parkinson's disease (PD) is a combination of multiple environmental and genetic factors. The Negev (Southern Israel) contains approximately 252.5 km(2) of agricultural cultivated fields (ACF). We aimed to estimate the prevalence and incidence of PD and to examine possible geographical clustering and associations with agricultural exposures. We screened all "Clalit" Health Services members in the Negev (70% of the population) between the years 2000 and 2012. Individual demographic, clinical, and medication prescription data were available. We used a refined medication tracer algorithm to identify PD patients. We used mixed Poisson models to calculate the smoothed standardized incidence rates (SIRs) for each locality. We identified ACF and calculate the size and distance of the fields from each locality. We identified 3,792 cases of PD. SIRs were higher than expected in Jewish rural localities (median SIR [95% CI]: 1.41 [1.28; 1.53] in 2001-2004, 1.62 [1.48; 1.76] in 2005-2008, and 1.57 [1.44; 1.80] in 2009-2012). Highest SIR was observed in localities located in proximity to large ACF (SIR 1.54, 95% CI 1.32; 1.79). In conclusion, in this population based study we found that PD SIRs were higher than expected in rural localities. Furthermore, it appears that proximity to ACF and the field size contribute to PD risk.

Figure 1

The figure shows the prevalence and incidence rates per 100,000 by year, between the years 2001 and 2012. Prevalence and incidence rates are presented for all cases and definite cases separately.

Figure 2

The figure shows the age and gender adjusted standardized incidence rates (SIRs) of Parkinson's disease in localities in Southern Israel. The full lines represent the borders of the southern district in Israel. The graduated symbols represent the SIR in each locality. Agricultural cultivated fields are highlighted in the map.