Geographic Model and Biomarker‐Derived Measures of Pesticide Exposure and Parkinson's Disease

Abstract

For more than two decades, reports have suggested that pesticides and herbicides may be an etiologic factor in idiopathic Parkinson's disease (PD). To date, no clear associations with any specific pesticide have been demonstrated from epidemiological studies perhaps, in part, because methods of reliably estimating exposures are lacking. We tested the validity of a Geographic Information Systems (GIS)-based exposure assessment model that estimates potential environmental exposures at residences from pesticide applications to agricultural crops based on California Pesticide Use Reports (PUR). Using lipid-adjusted dichlorodiphenyldichloroethylene (DDE) serum levels as the "gold standard" for pesticide exposure, we conducted a validation study in a sample taken from an ongoing, population-based case-control study of PD in Central California. Residential, occupational, and other risk factor data were collected for 22 cases and 24 controls from Kern county, California. Environmental GIS-PUR-based organochlorine (OC) estimates were derived for each subject and compared to lipid-adjusted DDE serum levels. Relying on a linear regression model, we predicted log-transformed lipid-adjusted DDE serum levels. GIS-PUR-derived OC measure, body mass index, age, gender, mixing and loading pesticides by hand, and using pesticides in the home, together explained 47% of the DDE serum level variance (adjusted r 2 = 0.47). The specificity of using our environmental GIS-PUR-derived OC measures to identify those with high-serum DDE levels was reasonably good (87%). Our environmental GIS-PUR-based approach appears to provide a valid model for assessing residential exposures to agricultural pesticides.

Ubiquitination Acutely Regulates Presynaptic Neurotransmitter Release in Mammalian Neurons

“…The consistent dysregulation of synaptic transmission in response to UPS malfunction might underlie early aspects of neurodegenerative diseases. This notion is supported by the accumulating evidence that pesticides inhibit UPS function (Wang et al, 2006) and that individuals living close to agricultural areas exposed to pesticides have an increased risk of developing Parkinson’s Disease (Ritz and Costello, 2006; Costello et al, 2009). Thus, it will be interesting to investigate whether malfunctioning of the rapid regulation of synaptic transmission by the ubiquitin-proteasome system--in addition to pointing towards a novel mechanism of synaptic regulation and plasticity--could serve as an early indicator of long-term neuronal dysfunction.…”

Residential Proximity to Methyl Bromide Use and Birth Outcomes in an Agricultural Population in California

“…These studies selected a buffer distance of 500 m or 0.5 mile (~ 800 m) for all pesticides, but did not use air monitoring data to confirm the validity of these buffer sizes for exposure assessment. In the study by Cockburn et al (2011), a 500-m buffer was justified based on a previous study that observed high specificity for serum DDE concentrations using a 1-km GIS buffer to estimate organochlorine exposure (Ritz and Costello 2006). Although this shorter buffer distance might be appropriate for assessing exposure to other pesticides, it does not appear to be sufficient for assessing exposure to fumigants, which are likely to drift much further away from the application site (Honaganahalli and Seiber 2000; Li et al 2005; Woodrow and Krieger 2007).…”

Parkinson’s disease risk from ambient exposure to pesticides

“…A technical discussion of our GIS-based approach is provided elsewhere, here we briefly summarize the data sources and exposure modeling process [26]. In a previous validation study, our GIS-derived measure for organochlorine exposures identified those with high serum dichlorodiphenyldichloroethylene levels with high specificity (87%) [32]. …”