The CDC regularly releases reports recording average levels of environmental chemicals, metals, and toxins in the general US population, and every report details increases in the number of foreign toxic chemicals found in the average person’s body (1). These toxins can affect many systems in the body and, unfortunately, the brain is included in that list. In previous articles, we’ve discussed brain health and zoomed in on the effects of brain inflammation and how it can be triggered by chronic inflammatory diseases and disorders, an unhealthy gut, disrupted blood sugar levels, and hormonal dysfunction. There is yet another culprit behind brain inflammation: neurotoxins.
How Do Neurotoxins Cause Brain Inflammation?
A neurotoxin is a substance that, whether naturally occurring or produced by humans, is capable of damaging the central nervous system (the brain and spinal cord). While some toxins are harmful in any amount, other substances can be tolerated in smaller doses, but if overloaded can cause adverse effects and act as neurotoxins (4). While each toxin interacts with the brain differently, there are some common effects that work together to create brain inflammation. Neurotoxins affect basic brain cell function by interfering with mitochondrial function, increasing oxidative stress, and deregulating protein turnover (3, 4). All three of these functions can result in inflammation, and when compounded with general age-related increase in oxidative stress and general antioxidant system decline, can begin the pathogenesis of a number of neurological symptoms and disorders (4).
Over 200 everyday chemicals are toxic to humans, such as flame retardants, phthalates and BPA (chemicals used in plastics), pesticides, and non-stick or stain-resistant products that are perfluorinated (5). These can affect attention, memory, behavior, cognition, and even physical coordination, increasing the risk of neurodegenerative disorders such as Parkinson’s and dementia (5).
Heavy metals are another commonly found toxin that can seriously impair brain function and cause brain inflammation. Because heavy metals are used so widely in industrial, pharmaceutical, agricultural, and commercial products, they are distributed quite widely throughout the environment and, of course, affect those working in manufacturing the most (6). The toxic burden on the humans and animals near these manufacturing sites is determined by a number of factors, including (6):
Type of toxin, and how it interacts with the environment
Amount of toxin present
Exposure type (oral, airborne, physical)
Population of the humans/animals themselves (age, gender, genetics, nutritional status)
The most toxic heavy metals are systemic toxins, which can cause multiple-organ damage, even at relatively low levels of exposure (6). The most common heavy metals are arsenic, chromium, lead, cadmium, and mercury (6).
Arsenic is widely used in insecticides, herbicides, and wood preservatives, though it can also be found in medicine, electronic, and industrial manufacturing processes (7). It can attach to other particles easily, including molecules in the air, water, and soil, and dissolves and spreads rapidly (7). Arsenic is thus able to contaminate entire lakes, rivers, or other water sources through contact with rain, snow, or industrial waste. This is why water is the biggest source of arsenic poisoning, with several millions of people being exposed every year (7, 8). However, food, cigarettes, and the products listed above can also cause arsenic poisoning (7). While cigarettes do contain low levels of arsenic, they may actually do the most harm by causing impairment of the ability to process ingested arsenic and expel it from the body (7).
Arsenic is not only associated with brain inflammation, but also brain dysfunction, increased risk for Alzheimer’s disease, and altered blood-glucose and HPA pathway functioning (8). Unfortunately, the most concentrated areas of arsenic pollution are Taiwan, China, India, and the Western U.S. (8).
Interestingly, chromium is both beneficial for the body to function and can be toxic. This difference has to do with its chemical makeup, which is indicated by a Roman numeral to indicate valency (the atoms’ ability to bond with other atoms). Chromium III is necessary for the body and offered as a supplement, but Chromium VI (Cr(VI)) is quite toxic and can harm cells via DNA damage (9). Because Chromium VI is heavily used in a number of processes including paint, chrome and stainless steel, and leather manufacturing, quite a bit of runoff can be found in water levels. While public health goals for Cr(VI) levels in water set the standard at incredibly low levels to avoid toxicity, many public sources of water exceed them (9). Chromium VI can affect lung and brain function and raise levels of oxidative stress and inflammation (10).
Lead, perhaps the most recognizable heavy metal, is quite toxic - there is no level of lead in the body that is safe, especially for children (11). Any level of lead in the blood is associated with inflammation, oxidative stress, and impaired brain function, resulting in lowered IQ, attention span, cognitive functioning, and neurodegenerative diseases (3, 4, 11).
Unfortunately, lead was quite commonly used until about 50 years ago and is still present in most people’s homes. It is most likely present in any building constructed before 1978, when lead in paint was banned, in some water pipes, and in the air and soil near airports (11). Antique jewelry and toys may contain lead, as well as certain imported candies, powders, and home remedies (11). Some hobbies may put people in contact with lead, such as glasswork, home renovation, working on electronics, use of firearms, and welding (11).
Cadmium reaches us through soil, water, and air, and can cause toxicity in every organ system, including the central nervous system (12). It is commonly used in paints, batteries, plastics, cigarettes, fertilizers, and is subsequently found in food production, especially in crops such as grains (12). It can also be found in some antique jewelry - after lead was banned, some jewelry manufacturers replaced lead with cadmium, which was an equally toxic swap (11). It is directly linked to neurotoxicity and can lead to neurodegenerative disorders such as Parkinson’s, Alzheimer’s, and Huntington’s diseases, as well as general behavioral changes and memory loss. Unfortunately, many adults and children exceed the weekly recommended intake for cadmium (12).
Similarly to lead, mercury can seriously impair brain function, affecting many areas of the brain, impairing vision, hearing, olfactory senses, motor movement, and cognition, ultimately leading to many different types of neurodegenerative diseases (3). Mercury is released into the environment through the mercury-containing airborne waste that is produced by burning fossil fuels and wood (13). This airborne waste finds its way back to our water, into the bodies of fish, and then into our bodies - almost every human on earth has some level of mercury in their body (13). (While fish is generally a very healthy protein option, large fish that eat other fish tend to be highest in mercury and may be avoided if you are worried about mercury exposure (13)).
Mold and Mycotoxins
Mold inhalation is associated with decreased neurogenesis, altered memory, anxiety, immune response, and brain inflammation (14, 15). The immune system activates when it comes into contact with the mold spore irritants. When someone is continually exposed to mold, the immune system is chronically activated, resulting in chronic inflammation (14, 15). Even non-toxic mold may thus become toxic and cause real harm to the body. Toxic mold, which contains mycotoxins, is even more harmful. Once mycotoxins reach the brain, they interfere with brain cell metabolism and function, affecting the brain the same way that heavy metals do (14). The most common source of mold is within businesses and homes. Mold is often found in warm, humid, poorly-ventilated, and especially water damaged buildings (14).
How to Avoid Toxins and Reduce Toxic Load
While toxins may be a part of our world, it doesn’t mean there’s no way to avoid them! There are many steps you can take to avoid toxins and reduce your toxic load:
Invest in a good water filter, to ensure your drinking and cooking water is as pure as possible.
Research your cookware and consider switching out any phthalate-containing non-stick pots and pans with ceramic, cast iron, or other non-toxic options.
Look for plastic products that state they are BPA, cadmium, and phthalate-free.