A pesticide used before the early 1980s may be associated with signs of Parkinson’s disease, according to a new study. The substance was commonly found in milk and dairy products in Hawaii, where it was used in the pineapple industry.
“The link between dairy products and Parkinson’s disease has been found in other studies,” said study author R. D. Abbott, a doctor with the Shiga University of Medical Science in Otsu, Japan.
“Our study looked specifically at milk and the signs of Parkinson’s in the brain.”
The research was published in Neurology, the medical journal of the American Academy of Neurology.
Researchers studied 449 Japanese-American men with an average age of 54. They took part in the Honolulu-Asia Ageing Study and were followed for more than 30 years and until their death, after which autopsies were performed.
Tests looked at whether participants had lost brain cells in the substantia nigra area of the brain, which occurs in Parkinson’s disease, while also measuring in 116 brains the amount of residue of a pesticide called heptachlor epoxide.
The study found that nonsmokers who drank more than two cups of milk per day had 40% fewer brain cells in that area of the brain than people who drank less than two cups of milk per day.
For those who were smokers at any point, there was no association between milk intake and loss of brain cells. Previous studies have shown that people who smoke have a lower risk of developing Parkinson’s disease.