A recent study from UCLA has confirmed that exposure to the herbicide Paraquat is linked with a heightened risk of Parkinson's disease. This combines with other research that has found other chemicals used on our foods and landscapes significantly increase the risk of Parkinson's.
The researchers, from UCLA's Fielding School of Public Health, studied 357 Parkinson's disease cases along with 754 control subjects - adults from Central California. The researchers determined increased exposure to the herbicide Paraquat through geographic mapping linking their home locations to agricultural use of the chemical on farms. Those living closer to farms that sprayed the herbicide were found to have a 36% increased risk of Parkinson's.
However, those who experienced a head injury combined with increased Paraquat exposure tripled their chances of having Parkinson's disease.
Researchers from Mexico's Unidad de Medicina Familiar also studied cases of Parkinson's together with exposure to the herbicide Paraquat among Mexican workers. They also found a positive association between exposure to this chemical and Parkinson's disease.
Paraquat is N,N′-dimethyl-4,4′-bipyridinium dichloride.
A study published last year from the Louvain Center for Toxicology and Applied Pharmacology of Brussels' Catholic University of Louvain concluded that pesticide exposure was also significantly linked to Parkinson's. Here the researchers analyzed and calculated the data from twelve peer-reviewed clinical studies that investigated Parkinson's disease together with pesticide exposure. They collected research conducted between 1985 and 2011.
The meta-analysis found that all twelve studies individually and collectively established a link between pesticide exposure and Parkinson's disease.
After calculating meta-data ratios and relative risk, the researchers found that Parkinson's disease incidence as diagnosed by a neurologist was more than two-and-a-half times for those exposed to more pesticides compared to those less exposed. Other risk calculations showed the increased incidence of Parkinson's disease to range from nearly double to 28% - which was the average of all cases studied.
But when the research focused upon farm workers involved in the growing of bananas, pineapples or sugarcane, the incidence of Parkinson's disease more than doubled that of lower-exposure individuals.
The researchers concluded:
The present study provides some support for the hypothesis that occupational exposure to pesticides increases the risk of Parkinson's disease.
Since this review study came out, other studies have investigated some of the worst pesticides, and the mechanisms by which they produce Parkinson's disease.
A study from Korea's Yonsei University studied the broad spectrum pesticide Rotenone – and how it damages nerve cells and pathways. The researchers found that Rotenone induces cell death in a process called with G2/M cell cycle arrest. G2/M cell cycle arrest blocks the process of mitosis that enables cells and their DNA to replicate – and more importantly among nerve cells - repair any DNA damage. Thus the insecticide basically blocks the ability of the nerve cell to repair itself – lending to the cells eventually dying off or mutating.