A study has found that male mice who breathed the weed-killer Paraquat lost their sense of smell, and the chemical also entered their brain and other tissues.
The study may help explain recent research finding higher rates of Parkinson’s Disease among farmers who were exposed to Paraquat.
To investigate further, researchers at the University of Rochester, in New York, exposed mice to low levels of Paraquat for 28 days. The mice breathed aerosolized Paraquat for 4 hours a day, 5 days a week.
Lead author Timothy Anderson explained, “Inhalation can provide a direct route of entry to the brain. If you inhale something and it goes into your nose, it can actually enter the neurons responsible for sense of smell, and travel into the brain.”
Loss of sense of smell is also an early symptom of Parkinson’s Disease.
The study found that Paraquat accumulated in tissues, with the most in the lungs. In the brain, the highest concentration of Paraquat was in the olfactory bulb, consistent with breathing it in through the nose.
Interestingly, both male and female mice were exposed to Paraquat, but only the males lost their sense of smell. This may help explain why Parkinson’s Disease is so much more common in men than women.
The study was published on December 29, 2020 in the journal Toxicological Sciences.
Citation: Anderson T, Merrill AK, Eckard ML, Marvin E, Conrad K, Welle K, Oberdorster G, Sobolewski M, Cory-Slechta DA . 2020. Paraquat inhalation, a translationally relevant route of exposure: disposition to the brain and male-specific olfactory impairment in mice. Tox Sci; doi: 10.1093/toxsci/kfaa183 [Online 29 December 2020].