A review of 38 studies published since 1983 has found a "relatively consistent relationship between pesticide exposure and [Parkinson's disease]," the authors wrote in the February issue of Environmental Health Perspectives.
The review was conducted by scientists from the Medical Research Council Institute for Environment and Health at the University of Leicester in Leicester, England and the National Centre for Environmental Toxicology in Swindon, England. The researchers wrote that they undertook the review because "to date, there has been no comprehensive literature review of the epidemiologic and toxicologic evidence to critically evaluate whether a causal relationship exists between exposure to pesticides and the development of PD or parkinsonism."
The authors concluded that "despite differences in study design, case ascertainment and definition, control selection, and pesticide exposure assessment" the studies did establish a "generic association" between pesticide exposure and Parkinson's, particularly in people over the age of 50 who were in contact with pesticides for more than 10 or 20 years.
Although the authors stated that there isn't enough evidence to link specific pesticides with Parkinson's, chemicals they reviewed included:
- Rotenone, an insecticide marketed under a variety of brand names, including Curex Flea Duster, Chem-Mite and Derrin
- Paraquat, an herbicide commonly found in Ortho Weed & Spot Killer and Sweep
- Maneb, an herbicide often combined with paraquat. Brand names include Farmaneb and Manesan
- Cyclodiene, a type of organochlorine pesticide marketed under the names Thionex, Phaser and Thioden
- Pyrethroid, an insecticide with a variety of trademarks, including Capture, Ammo, Warrior, Mustang and Pyganic
Dr. Charles Benbrook, chief scientist for The Organic Center, based in Greenfield, Mass., said the researchers' findings didn't come as a surprise. "The link between pesticides and Parkinson's has been reasonably well established. I think these researchers were a bit more conservative than others, but they still reached the same conclusions."
Benbrook, who has written several papers on the perils of pesticides, will speak Feb. 19 at the annual meeting of the American Association for the Advancement of Science. He and fellow panelists Alan Greene of drgreene.com, Chensheng Lu of Emory University and Philip Landrigan of the Mount Sinai School of Medicine will discuss "Opportunities and Initiatives to Minimize Children's Exposures to Pesticides."