(Beyond Pesticides, December 11, 2015) Milk contaminated with the long-banned and toxic organochlorine pesticide heptachlor in Hawaii has been found in the brains of men that were more likely to develop Parkinson’s disease, according to a new study. This study adds to a large body of evidence linking pesticide exposure to Parkinson’s disease.
Researchers of the study, titled “Midlife milk consumption and substantia nigra neuron density at death” and published in the journal Neurology, collected milk intake data from 1965 to 1968 for 449 men aged 45-68 years withpostmortem examinations from 1992 to 2004. Neuron density was measured in an area of the brain called substantia nigra (SN). As Parkinson’s develops, cells are destroyed in certain parts of the brain stem, particularly in the SN, a crescent-shaped cell mass. Measurements of brain residues of heptachlor epoxide, a heptachlor metabolite that is persistent and more toxic than its parent chemical, were also taken.
“Among those who drank the most milk, residues of heptachlor epoxide were found in 9 of 10 brains as compared to 63.4%…for those who consumed no milk,” the researchers wrote. Neuron density was lowest in subjects who consumed the highest amounts of milk.
The researchers looked at milk because it can bioconcentrate, or accumulate, certain organic pollutants such as organochlorine pesticides. Hawaii is an area that is of particular importance due to excessively high levels of heptachlor epoxide what were reported to contaminate the milk supply during the time that study participants were being followed. Heptachlor was widely used on pineapple plantations and the “green chop,” or tops of the pineapple, were fed to cows. It was widely known that milk was contaminated with elevated levels of helptachlor in the 1980’s. EPA allowed the use of heptachlor on pineapples to continue long after other agricultural uses had been suspended.
Heptachlor was used as an insecticide between 1953 and 1974 as a soil and seed treatment; however, nearly all registered uses of heptachlor have been canceled. Uses continued in Hawaii under an exemption until 1994. EPA has classified heptachlor as a Group B2 probable human carcinogen.
Parkinson’s disease is a degenerative disorder of the central nervous system that affects the motor system, resulting in symptoms of tremor, stiffness, or slowing of movement. Organochlorine pesticides may have a role in the causation of Parkinson’s. In 2013, a study revealed that individuals with a genetic mutation were at increased risk of Parkinson’s disease if they were also exposed to low doses of pesticides. Another study in the journal Cell also provides firm evidence linking pesticides to Parkinson’s disease, as the researchers used pesticides to find the mechanisms by which the disease manifests itself. Beyond Pesticides has worked to increase public awareness of the link between pesticide use and Parkinson’s disease through the Pesticide Induced Diseases Database, which currently features over 100 peer-reviewed studies that have researched the pesticides-Parkinson’s connection.
As the connection between Parkinson’s and pesticide use becomes increasingly clear, pressure will continue to build for practices and methods that exclude pests without the use of hazardous chemicals. Whether in airplanes, farms, gardens, lawns, waterways, inside one’s own home, or the numerous other places where pesticides are often used, there are non-toxic and least-toxic alternatives that do not necessitate the use of hazardous chemicals. For more information on the link between pesticides and Parkinson’s, see Beyond Pesticides’ Pesticide Induced Diseases Database, or read our 2008 Pesticides and You article “Pesticides Trigger Parkinson’s Disease.”
All unattributed positions and opinions in this piece are those of Beyond Pesticides.