L'Association pour la santé environnementale du Québec / Environmental Health Association of Québec

Mechanisms of the impact of pollution on brain function

Neurodevelopment, neurodegeneration and chemical sensitization


The brain is especially vulnerable to damage from exposures to airborne chemicals. This includes deficits in brain development in young children, neurodegeneration in adults, and sensitization in susceptible individuals.

Everyone is exposed to numerous chemical pollutants every day. Some accumulate and most of us have a myriad number of chemical pollutants stored in our bodies. We attempt to manage this toxic burden through our natural detoxification systems, but if the burden is too much, some of our cells function abnormally or die. The World Health Organization has stated that pollution exposure is the fifth most common contributor to developing chronic diseases, after tobacco use, harmful use of alcohol, unhealthy diets and physical inactivity. These diseases include most common chronic cardiovascular, respiratory and neurological diseases.

Daily pollution exposures can get into the brain and impact brain cells. The effect can be cell death, leading to neurodegenerative disorders, like Parkinson’s and Alzheimer’s disease. These exposures can also induce sensitization. When this occurs, these people describe a heightened sense of smell and develop symptoms after exposure to numerous different chemicals commonly found in the air. These are chemicals that these people used to tolerate and are tolerated by most other people. The condition is called multiple chemical sensitivity (MCS). Almost 4% of the population in North America, Europe, Australia and Japan have been diagnosed by a doctor with MCS and the number is increasing.

Unfortunately, no objective test is available in the doctor’s office or clinical laboratory to support or prove the diagnosis. As a result, many people are stigmatized because they are not believed by their doctor, family members, friends or employers.

However, there is now accumulating and compelling evidence published in respectable, peer reviewed journals that MCS is a biological condition. The dissemination of this knowledge should help to reduce the stigma, enhance support for accommodation and eventually lead to better treatments.

An online zoom presentation on December 14, 2020 at 7:00 pm, by Dr. John Molot, will review the science which explains the mechanisms for MCS and why some people may be more likely to develop it.

Understanding these concepts is essential in order to be able to develop a self-management plan for a better quality of life.