Did you know that we humans can encounter more than 80,000 chemicals in the environment? Frances Jensen, M.D., president of the American Neurological Association, explains how these contaminants may be affecting our immune systems.
We’re constantly breathing, touching, and ingesting chemicals from the air, from our food, and from soil and surfaces. Collectively known as our “exposome,” we’re learning that these exposures may be a major factor in neurological disease. While most of us have heard of environmental contaminants causing asthma or cancer, neuroscientists are discovering how exquisitely sensitive the nervous system is to them.
An under-recognized threat
From autism to Alzheimer’s disease, from ADHD to multiple sclerosis, many neurological disorders are on the rise. Chemical exposures may play a part.
Consider cognitive function: In 2020, NYU researchers estimated that exposures to chemicals including lead, methylmercury, certain pesticides, and flame retardants have affected IQs across the United States, causing more than 700,000 cases of intellectual disability and the loss of more than 160 million IQ points in recent decades. There’s also evidence that chemical exposures can increase the risk of diseases like dementia, Parkinson’s, and ALS. And that’s just what we know so far. While regulations are helping combat some exposures, we have yet to understand some of the newer environmental threats such as nanoplastics, which are now permeating our air, water, and food chains.
The National Health and Nutrition Examination Survey suggests that more than half of people in the United States are exposed to detectable levels of major pesticides. Since the 1940s, we’ve also seen massive production of industrial chemicals, especially in plastics. Air pollution is equally important; we breathe in tiny particles carrying chemicals that get absorbed quickly through the bloodstream or nerves. Some of these exposures are already linked to cancer and lung disease, but we have yet to determine how our brain and nervous systems are affected.
The most disadvantaged people in our society bear the greatest risk from environmental contaminants. Poverty may drive people to take high-risk jobs; live in areas where they’re exposed to road pollution, agricultural pesticides, industrial operations, or lead-filled buildings; and consume cheaper foods produced with less regard to chemical safety. They may also be more likely to experience issues like malnutrition and chronic disease that combine with chemical exposures to amplify neurological risks. Addressing these factors would make a major difference for the neurological health of people in poverty.
Tools for better solutions
Environmental contaminants and chemicals can interact with each other, our genetics, and issues like stress and nutrition to impact health. Because we encounter many environmental toxins at low levels over long periods of time, it can be hard to trace their neurological effects and understand what amounts will tip the balance toward disease. Yet that’s exactly what we need to do if we’re going to address those impacts.
New scientific approaches and cutting-edge tools are paving the way, including artificial intelligence, advanced measurements of how genes activate or go quiet in response to contaminants, and potential new tools to monitor a person’s chemical exposures in the workplace. We’re also getting a clearer picture of how some toxins interact biologically with the nervous system. Although there’s still a lot to learn, the science is promising. When we understand this collective and interactive “exposome” better, we can take steps to protect everyone’s neurological health.