Pesticides and other pollutants could be the main cause of Parkinson's

The main causes of the disease Parkinson must be traced back to exposure to various types of polluting substances.In particular, some pesticides, industrial solvents such as trichlorethylene and, in general, air pollutants would play a decisive role.This is what one stated, in no uncertain terms editorial published at the beginning of January on Journal of Parkinson's Disease, a highly specialized scientific journal.According to the researchers, “the disease of Parkinson It is the fastest growing brain disorder in the world and exposure to environmental toxicants it is the main cause”.In an attempt to give alternative explanations, the analysis also took into consideration potential external factors other than pollution - such as the improvement of diagnostic skills, the aging of the population and genetics - all however considered unsatisfactory.

Based on previous evidence, pesticides in particular would be the environmental pollutants with the clearest relationship to the disease.In fact, there are numerous epidemiological and animal studies that they support a causal relationship between some pesticides and Parkinson's.In this regard, one of the first clues came in the 1980s, when seven young adults developed end-stage parkinsonism subacutely after intravenous injection of the synthetic drug 1-methyl-4-phenyl-l,2,3 ,6-tetrahydropyridine (MPTP).MPTP, once assimilated by the body, is converted into its metabolite MPP+, which shows a notable structural similarity to paraquat, one of the most used herbicides in the world.Subsequent epidemiological research has then strengthened the thesis that there is a strong link between Parkinson's disease and previous exposure to pesticides.In some cases, as in a study conducted in Canada, the correlation between the two variables was very strong, that is, equal to 0.96 when the maximum is 1.“It is important to note that the risk of developing Parkinson's – we read in the editorial – is not limited to those who work professionally with pesticides.Those who live near sprayed fields are also at risk.For example, in France, it emerged that the increased risk of developing the disease also extends to those who live near agricultural land."

However, since pesticides are unlikely to be a satisfactory explanation for the high rates of the disease in urban areas, it is likely that other environmental contaminants are also responsible.Among all, the most popular is the synthetic chemical substance trichlorethylene.First created in 1864, trichlorethylene has become widespread since the 1920s and has since found myriad military, industrial and commercial applications, including metal degreasing, coffee decaffeination and dry cleaning of clothes.It is estimated that one in 12 workers in the UK and 10 million Americans have worked with this volatile solvent.To understand the extent of the contamination, just think that, in Italy, a study found the presence of the substance in the urine of 75% of individuals analyzed.Trichlorethylene is a known carcinogen and its toxic effects have been known since at least 1932.However, it was in 1969 that exposure to the substance was linked to the typical symptoms of Parkinson's for the first time.In 2008, researchers then discovered that three workers developed the disease after using trichlorethylene for many years to degrease and clean metal equipment.Four years later, a study confirmed initial fears by finding a 500% higher risk of developing Parkinson's among individuals who had exposure to the solvent than their twin brothers.

Finally, in urban areas, it is possible that air pollution plays a decisive role in the etiology of Parkinson's, whose potential link with the neurological disease is only now beginning to become clear.According to a study published this year on Neurology, people living in regions with high levels of air pollution have a 56% greater risk of developing Parkinson's disease compared to those who live in areas with lower levels of air pollution.However, establishing which specific pollutant is responsible for the pathology is not simple.Currently, research is focusing on atmospheric particulate matter.Suspended polluting particles, especially very fine ones, are in fact able to bypass the body's normal protection mechanisms and penetrate the nose, respiratory tract and lungs.And it is known that these particles are often composed of heavy metals, coming from cars and industry, toxic to brain cells.In essence, although further confirmation is needed, as in the case of air pollution, it is possible to state that the role of environmental contamination in the development of Parkinson's is quite evident and alarming.

[by Simone Valeri]