Paris, France – June 04, 2009 – The cause of Parkinson’s disease (PD), the second most frequent neurodegenerative disease after Alzheimer’s disease, is unknown, but in most cases it is believed to involve a combination of environmental risk factors and genetic susceptibility. Laboratory studies in rats have shown that injecting the insecticide rotenone leads to an animal model of PD and several epidemiological studies have shown an association between pesticides and PD, but most have not identified specific pesticides or studied the amount of exposure relating to the association.  

A new epidemiological study involving the exposure of French farm workers to pesticides found that professional exposure is associated with PD, especially for organochlorine insecticides. The study is published in Annals of Neurology, the official journal of the American Neurological Association.  

Led by Alexis Elbaz M.D., Ph.D., of Inserm, the national French institute for health research in Paris, and University Pierre et Marie Curie (UPMC, Paris 6), the study involved individuals affiliated with the French health insurance organization for agricultural workers who were frequently exposed to pesticides in the course of their work. Occupational health physicians constructed a detailed lifetime exposure history to pesticides by interviewing participants, visiting farms, and collecting a large amount of data on pesticide exposure. These included farm size, type of crops, animal breeding, which pesticides were used, time period of use, frequency and duration of exposure per year, and spraying method. 

The study found that PD patients had been exposed to pesticides through their work more frequently and for a greater number of years/hours than those without PD. Among the three main classes of pesticides (insecticides, herbicides, fungicides), researchers found the largest difference for insecticides: men who had used insecticides had a two-fold increase in the risk of PD. 

“Our findings support the hypothesis that environmental risk factors such as professional pesticide exposure may lead to neurodegeneration,” notes Dr. Elbaz.  

The study highlights the need to educate workers applying pesticides as to how these products should be used and the importance of promoting and encouraging the use of protective devices. In addition to the significance of the study for those with a high level of exposure to pesticides, it also raises the question about the role of lower-level environmental exposure through air, water and food, and additional studies are needed to address this question.  

Reference: Alexis Elbaz, Jacqueline Clavel, Paul J. Rathouz, PhD 6, Frédéric Moisan Jean-Philippe Galanaud, Bernard Delemotte, Annick Alpérovitch, Christophe Tzourio, Professional exposure to pesticides and Parkinson’s disease, Annals of Neurology, Press Release Wiley Blackwell, June 4, 2009

Pyrethrin and Pyrethroide insecticides are commonly applied in homes and businesses and on some agricultural crops. This research used a two-state regional approach to analyze reports of acute pesticide poisonings due to Pyrethrin and Pyrethroide insecticides.  

The Washington State Department of Health and the Oregon Public Health Division collected pesticide poisoning surveillance data from 2001 through 2005. Cases were included if they involved exposure to at least one Pyrethrin or Pyrethroide insecticide. Descriptive statistics were calculated; differences between categories were assessed using Chi-square analysis.  

A total of 407 cases fit our definition. Overall, the rate of poisoning in Oregon was significantly higher than in Washington (incidence rate ratio 1.70, 95% confidence interval 1.40, 2.07), and rates for both states generally increased during the time period. For both states, most exposures resulted in low severity illnesses (92%), and most were classified as possible cases (73%). Only about one-fourth of cases were related to a person’s work. The most common category of clinical signs and symptoms of illness was respiratory (52% of cases), followed by neurological (40% of cases). Exposure route was predominantly inhalation; there was no association between route and case severity. There was a significant association between illness severity and losing time from work or regular activities (p<0.0001).  

Although the majority of Pyrethrin and Pyrethroide poisoning cases were low in severity, adverse reactions have occurred, as transpired in Oregon in 2005. Regional analysis has the potential to improve the surveillance system and provide unique opportunities for targeting preventive interventions. 

Reference:

Walters JK, Boswell LE, Green MK, Heumann MA, Karam LE, Morrissey BF, Waltz JE., Pyrethrin and Pyrethroide illnesses in the Pacific Northwest: a five-year review, Oregon Department of Human Services, Public Health Division, Office of Environmental Public Health, Toxicology, Assessment, & Tracking Services, Oregon Worker Illness and Injury Prevention Program, Portland, OR 97232, USA, Public Health Rep. 2009 Jan-Feb;124(1):149-59.