In our modern world, we are immersed every day in a toxic soup of heavy metals, chemicals, pesticides and other toxins that were either non-existent or not nearly as prevalent a hundred years ago. There really is no corner of the earth that is still completely untouched by pollution and contamination with these substances. Our species did not evolve to be able to handle such a daily assault on our bodies, and the total load of environmental toxins has taken a toll on our collective health, both mentally and physically. Heavy metals are some of the biggest offenders that affect neurodevelopment and brain functioning, especially as it relates to autism and ADHD.

Aluminum

Looks good, right? Healthy fish with vegetables and herbs – but the aluminum foil adds unwanted toxic metals. Aluminum is a neurotoxin that causes brain inflammation and is associated with Alzheimer’s and Parkinson’s disease.¹ Studies have also found high levels of aluminum in brain tissue of people with autism.² Sources of aluminum include baking powder, unfiltered tap water, tea leaves, food additives, and aluminum cooking utensils and foil. (If you must use foil, line it with parchment paper to prevent the food from touching the aluminum and leaching heavy metals.)

Another source of aluminum is vaccines, particularly the Hep B vaccine, dTap, and childhood combination vaccines like Pediarix that combine these with other aluminum-containing vaccines. Though the CDC says that the amount of aluminum in vaccines is negligible compared the the daily amount consumed in food, the problem is the way in which it is delivered. Much of the aluminum we consume orally becomes chelated by binding with other minerals in the digestive tract and then removed from the body. Aluminum in vaccines is injected directly into the bloodstream, bypassing this process. The FDA has regulations regarding how much aluminum can be administered daily in an IV. Many of these vaccines contain aluminum amounts much higher than these regulations.³ Additionally, adjuvants in vaccines allow this aluminum to cross the blood-brain barrier, making them extremely toxic to neurodevelopment. If you choose to vaccinate, you can space out the vaccines and avoid combo vaccines to prevent getting too much aluminum at one time.

Mercury

Much has been made, accurately or not, regarding the controversial association of mercury in vaccines and autism. However, the truth is that thimerosal, the mercury-containing preservative, has not been used in childhood vaccines since 2001. In cases where it has been added (dTAP), it is later removed during the production process, though slight traces may remain. The MMR, IPV, and varicella vaccines do not contain and have never contained thimerosal. The only exception is the flu vaccine, which still contains thimerosal in one of two forms of the vaccine.

There are other sources of mercury in our food and environment to be wary of, though. The single biggest source of human exposure is from eating contaminated fish. Mercury from PCBs in the ocean wind up in fish, especially larger fish higher up in the food chain, such as ahi, albacore and yellowfin tuna, swordfish, orange roughy, king mackerel and mahi-mahi. It’s best to eat smaller fish that have lower cumulative amounts of mercury, such as sardines, mackerel, and chunk light tuna, and limit to 3 times per week (especially if pregnant).

It’s important to note that eating fish is not bad for you! If you are eating the right fish, the benefits of neuro-protective omega-3 fatty acids far outweigh the risk of small amounts of mercury. In fact, the same study that found a correlation between prenatal mercury exposure and ADHD also found that fish consumption during pregnancy is protective of these behaviors.⁴

Mercury also leaches out of old amalgam dental fillings. If you have a lot of silver fillings, it’s important to have them safely removed by a holistic dentist who takes special precautions. They should never be removed during pregnancy or while breastfeeding.

Lead, cadmium and arsenic

Lead is another neurotoxin that interferes with neurotransmitter function. Exposure to lead can alter GABA and dopamine function and lead to ADHD behaviors including lack of inhibition, impaired mental and social functioning, reduced IQ and learning problems, as well as anxiety. Studies show lead and cadmium levels are higher in ADHD children and are associated with susceptibility to ADHD and symptom severity in school-age children.⁵

Lead accumulates in the blood primarily from exposure through drinking water (which leaches from old pipes), peeling paint from houses built before 1978, industrial air pollution and soil. You can have your soil and water tested for lead and other toxin levels. Be sure to clean up peeling paint if you think it contains lead, but be aware of safety when stripping or removal, as this creates lead-containing dust particles in the air. Lead in paint is stable when it’s on the walls – it’s only a danger for small children who may eat paint chips or put dusty fingers in their mouths, or breathe in dust during removal.

Arsenic is found in contaminated soil and is taken up by plants grown in it, particularly rice. Many people on gluten-free diets unknowingly consume toxic amounts of arsenic, due to the prevalence of rice flour in substitutes for wheat products. Some common baby cereals are also made from rice. (I don’t actually recommend cereal as one of baby’s first foods – it is very difficult to digest, and more nutritious first foods are egg yolk, avocado, and liver.) A meta-analysis of 14 studies found statistically significant higher arsenic concentrations, in hair and in blood, for children diagnosed with ASD compared with controls.⁶

Copper toxicity

Copper is a trace mineral that we need in our bodies in small amounts. Copper is naturally present in small amounts in foods but is often in balance with zinc. But a diet too high in copper or deficient in zinc can throw off this balance. Copper competes with zinc for binding in the body, and we need a low ratio of copper to zinc. If the ratio of copper to zinc is too high, copper collects in the tissues and can lead to toxicity. Foods high in copper include chocolate, nuts, and shellfish. Other sources of excess copper include copper cookware, copper pipes, and copper IUDs.

Too much copper causes oxidative stress and neurological symptoms such as depression, irritability, fatigue, excitability, and difficulty focusing.⁷ It also increases oxidation of a critical lipid (fat) in the membranes of brain matter, nerve tissue and the spinal cord. This effect was linked to autism in a 2008 study that found lower levels of this lipid in cellular membranes of autistic subjects, suggesting oxidative stress and copper toxicity. The study also suggests that children with autism have abnormal copper metabolism, contributing to more toxicity.⁸  

Another 2011 study of 79 autistic individuals found significantly elevated plasma copper and lower zinc:copper ratio compared to neurotypical individuals. The results of the study showed that autistic children significantly improved with respect to hyperactivity and stimming after zinc therapy.⁹ Zinc deficiencies are also documented in children with ADHD in a study that suggests that zinc levels might have a beneficial effect on information processing in ADHD.¹⁰

Zinc is an important micronutrient necessary for the chemical formation of hormones and neurotransmitters, and is important to brain function. Zinc deficiencies can result in skin disorders like eczema and dermatitis, as well as digestive problems and malabsorption.

The remedy for a disproportionate ratio of copper to zinc is to offset the imbalance by increasing dietary zinc and reducing copper. Foods that are high in zinc but low in copper include red meat, poultry and pumpkin seeds (shellfish is too high in copper). Vitamin C is also a gentle, effective chelator of copper that has been displaced by zinc. Avoid copper cookware, and filter your water!

Other environmental toxins

Besides heavy metals, there are other toxic substances in our environment that affect neurodevelopment and brain health. They come from air pollution, plastics, and chemicals added to common household products.

• Polycyclic aromatic hydrocarbons (PAHs)

PAHs come from urban air pollution, cigarette smoke, wildfire smoke and fossil fuel exhaust fumes. We breath them in, and they collect in our fat tissues. The closer the proximity to a freeway, the higher the exposure.

PAHs are particularly damaging to neurodevelopment in the case of prenatal exposure. They can pass through the placenta and affect a developing fetus. They can cross the blood-brain barrier. They are also mutagenic, which means they can affect offspring by altering DNA. These epigenetic changes can then be passed down through generations. There is evidence that these air pollutants negatively affect behavior and attention and can cause developmental delays.¹¹

Supporting with antioxidant vitamins A and E has been shown to protect against the harmful effects of PAHs.¹² Vitamins A and E are protective antioxidant and fat-soluble vitamins, meaning they are stored and transported with fats and must be consumed with fat in order to be absorbed properly. Fat soluble vitamins are normally found in fat-containing foods such as butterfat (ghee), liver and cod liver oil in the case of pre-formed vitamin A (retinol) and nuts and seeds in the case of vitamin E. Vitamin A precursors, called carotenoids, are found in orange, yellow and leafy green vegetables. Carrots are known for their high beta carotene content, but spinach is even higher. However, this pro-vitamin A must be converted to retinol in the body, and this is an inefficient process.

• Phthalates

Phthalates are chemicals found in plastics such as shower curtains, clear plastic wrap and food containers. They are also used in synthetic fragrances in household cleaners and cosmetic products. Phthalates are a xenoestrogen (they mimic estrogen) and an endocrine disruptor. They can affect DNA function and gene expression. Researchers have linked phthalates to asthma, ADHD, breast cancer, obesity and type II diabetes, low IQ, neurodevelopmental issues, behavioral issues, autism spectrum disorders, altered reproductive development and male fertility issues.¹³ Prenatal exposure, in particular, affects neurodevelopment because of the alteration in maternal thyroid and sex hormone production, which are both critical to neonatal brain development and neural circuits that affect later social cognition.¹⁴

Childhood and prenatal exposure to phthalates is associated with ADHD, oppositional defiant disorder (ODD) and conduct disorder. Elevated urinary phthalates correlate to increased BASC scores including aggression, attention problems, conduct problems, depression, and externalizing problems, while adaptability, executive function, and emotional control rated lower.¹⁵

Phthalates are also connected to autism spectrum disorders in multiple studies. Gestational phthalate exposure resulted in higher incidence of autistic traits in boys in a Canadian study,¹⁶ as well as an increase in the number of reported ASD diagnoses in a Swedish study of exposure to indoor air pollution from PVC flooring, a known significant source of phthalates.¹⁷ There is also a link between phthalates and depression and anxiety, as found in a 2020 study of Chinese university students.¹⁸

There is currently very little regulation of phthalate use, though four kinds of phthalates are included in California’s Prop 65 warning. They are unfortunately ubiquitous in our modern world, and it is impossible to completely avoid them. But you can reduce your exposure by keeping food in glass or stainless steel containers and buying fragrance-free cosmetics, body care and household cleaning products.

• BPA

Bisphenol-A is a chemical added to make hard plastics and epoxy resins. It is found in hard, clear plastic bottles (with the number 7), in the lining of canned goods to prevent the metal from rusting, and in newer dental sealants and fillings. It’s also a chemical used on thermal receipt paper from the grocery store. Ever notice store clerks wearing latex gloves? That’s why (pre-pandemic, that is). BPA has been largely removed from baby bottles, but it is still widely prevalent.

Like phthalates, BPA is a xenoestrogen and an endocrine disruptor, even at very low doses. BPA binds to estrogen receptors that regulate hormone transcription and gene expression. They also target androgen receptors and suppress thyroid hormone receptors (affecting neurodevelopment in a similar mechanism as that of phthalates) and increase adipose (fat) tissue. BPA has been linked to various diseases including diabetes, cardiovascular disease, obesity, and cancer. BPA can alter DNA methylation, leading to epigenetic changes that can be retained across generations.¹⁹

Higher BPA levels have been linked to both autism and ADHD. Some of the behavioral symptoms associated with BPA include inattention, hyperactivity, conduct problems, internalizing and externalizing behaviors, anxiety and depression.²⁰

You can find plastics labeled BPA-free, though its substitute, BPS, may be even more potent. The best way to avoid BPA is to avoid plastics as much as possible and use glass and stainless steel instead. Avoid canned foods and buy fresh as much as possible. Toss your store receipts or when you have a choice, ask them not to print one. Once you’ve avoided the source of BPA, it can pass out of the body fairly quickly.

References

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©️ 2021 Angie Spinelli