An epidemic of childhood behavioral disorders is sweeping the globe. Research suggests that heavy metal toxicity may be one of the underlying causes of childhood behavioral disorders, including ADHD, autism spectrum disorder, and tics. Read on to learn about the relationship between heavy metals and behavior, the primary sources of heavy metal exposure, and why detoxification may be beneficial in the treatment of childhood behavioral disorders.
Behavioral disorders: A pandemic disabling our children
It is normal for children to be energetic and occasionally distracted, upset, or argumentative. However, when these behaviors become disruptive and cause harm to the child or others, a diagnosis of a behavioral disorder may be made. Recent research indicates that one in six children in the United States is afflicted with developmental and behavioral disorders, including attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder, autism spectrum disorder (ASD), anxiety disorder, learning disorders, and conduct disorders. (1)
According to neurology experts Philippe Grandjean and Philip Landrigan in a 2014 report in The Lancet Neurology, “a silent pandemic of neurodevelopmental toxicity” is disabling children around the world and contributing to the meteoric rise of ADHD, ASD, and other behavioral disorders. (2) What is responsible for the rapidly rising rates of behavioral disorders in children? Research indicates that heavy metal exposure promotes neurodevelopmental toxicity and may be one of the underlying causes of childhood behavioral disorders.
Childhood exposure to mercury occurs primarily through the consumption of seafood, vaccines containing thimerosal, and dental amalgams. Mercury is a potent neurotoxin that directly passes through the blood–brain barrier and accumulates in brain tissue and the spinal cord, disrupting neurological function. Children are especially susceptible to the harmful effects of mercury, and a growing body of research indicates that mercury exposure is associated with an increased risk of behavioral disorders.
- Prenatal mercury exposure, measured through samples of cord blood, is associated with ADHD symptoms in children. (3)
- Postnatal mercury exposure from thimerosal in vaccines has been linked to ASD, ADD, ADHD, and tic disorder. (4, 5, 6)
- A systematic review of 44 studies concluded that mercury levels were significantly higher in the whole blood, red blood cells, and brains of autistic subjects compared to controls. (7)
- Mercury content in ambient air is linked to an increased prevalence of autism in children. (8)
- Even low levels of mercury are harmful to the developing brain and have been associated with learning disabilities. (9)
Heavy metals may play a role in your child’s behavioral disorder. Learn how to reduce your exposure.
Lead is a pervasive environmental toxin that adversely affects the developing nervous system in children. Children may be exposed to lead through paint chips, dust, and water pipes in homes built prior to 1978, as well as dirt, drinking water, and air pollution. (10)
- In animal studies, prenatal exposure to lead has been found to alter synapses in the brain, impairing neurotransmission and learning behaviors. (11)
- Children who grew up near the location of a former lead refinery were found to have a higher risk of ADHD. (12)
- Even very low levels of lead have adverse effects on the brain and behavior in children. Blood lead levels less than 1.8µg/dL, well below the CDC’s recommended threshold of 5µg of lead per dL of blood, are associated with an increased risk of ADHD. This suggests that there is no safe limit for lead exposure in children. (13)
Manganese is a heavy metal that is required by the body in small amounts to create antioxidant enzymes, for the metabolism of carbohydrates and amino acids, and to promote bone development and wound healing. It can be found in foods such as green leafy vegetables, tea, and legumes. However, manganese toxicity can occur when manganese dust from sources such as chemical manufacturing and welding is inhaled or when high levels of manganese are present in drinking water.
- Manganese exposure has been linked to ADHD. (14)
- Children exposed to high levels of manganese through drinking water have been found to experience diminished intellectual function and behavioral problems. (15, 16, 17)
Aluminum is a pervasive heavy metal used as an adjuvant in vaccines, as a food additive, and in metal cookware, beverage cans, antacids, and antiperspirants. Research has found high levels of aluminum in the brain tissue of deceased individuals with autism; the aluminum was most concentrated in immune cells of the brain, suggesting that aluminum elicits a neuroimmune response. (18) A significant correlation also exists between the amounts of aluminum adjuvant administered to children in vaccines and the prevalence of autism spectrum disorder, further supporting the theory that aluminum adversely impacts the developing brain. (19)
Arsenic has become a common contaminant in soil and groundwater due to its prevalence as a byproduct of industrial manufacturing processes. Arsenic is also present at high levels in conventionally raised poultry, which is fed arsenic-containing drugs, and in rice from India and areas outside of California. Urine arsenic levels have been associated with decreased IQ in children. (20)
How heavy metals harm the brain
Heavy metals pass through the blood–brain barrier and accumulate in brain tissue. Once in the brain, they harm neurological function through several mechanisms.
- Heavy metals displace essential minerals such as zinc and iron that are required for neurotransmitter production. (21)
- Heavy metals induce oxidative stress, which reduces neuronal plasticity and impairs learning and behavior. (22)
- Aluminum accumulates in immune cells of the brain. This may provoke an inflammatory immune response that ultimately affects neurological function and behavior. (23)
Heavy metal testing
Heavy metal testing is a controversial topic because each of the currently available methods of testing—hair, urine, and blood—has some drawbacks.
- Hair testing. Hair testing has become a popular method for assessing heavy metal status. However, using hair testing alone, we cannot know for certain whether a high level of a metal in the hair reflects a significant body burden of that metal or indicates that the patient is efficiently eliminating the metal through the hair and thus has a low level of it in the body.
- Urine testing. Urine heavy metal provocation tests, which use a chelating agent such as DMSA to provoke a release of heavy metals into the circulation, present problems similar to those with hair testing; it is possible that a metal may be high in the urine because the body is efficient at excreting it, or it may reflect a high body burden of the metal. Another problem is that reference ranges for provoked urine results have not been developed or validated.
- Blood testing. Blood testing is problematic for assessing heavy metal status because heavy metals typically circulate in the blood for only a short time before becoming sequestered in tissues.
While each of these testing methods is faulty when used alone, combining a couple of techniques may be a more accurate way to assess heavy metal toxicity. For example, you could do a provoked and an unprovoked urine test, or a hair test and a provoked urine test. Combining two tests may paint a more accurate picture of the body’s total heavy metal burden.
How to avoid heavy metals
Reducing exposure to heavy metals may lower the risk of childhood developmental disorders. Pregnant women should be conscientious about heavy metal exposure because heavy metals cross the placenta and can affect the brain of the developing fetus. Parents with young children also need to be careful since the brain is especially sensitive to toxic insults during childhood.
There are a handful of steps you can take to reduce exposure to heavy metals:
- Don’t use aluminum pans for cooking. Choose stainless steel or enameled cast iron instead.
- Choose seafood low in mercury. The Monterey Bay Aquarium’s Seafood Watch program is a helpful tool for learning which types of seafood are highest and lowest in mercury. Wild-caught Alaskan salmon, wild-caught Pacific sardines, and pole-caught albacore tuna are among the lower-mercury choices; Atlantic cod, halibut, shark, and swordfish tend to be much higher in mercury.
- Choose thimerosal-free vaccines.
- Filter your drinking and bathing water. Invest in a high-quality drinking water filtration system that removes heavy metals.
- Choose organic chicken. Conventionally raised chicken is high in arsenic.
- Limit intake of brown rice and white rice from India and areas outside of California. Rice from these regions tends to be high in arsenic. White rice from California is lower in arsenic and thus a safer option. See my article “Arsenic in Rice: How Concerned Should You Be?” for more information.
- Prevent heavy metal pollution from entering your home. If you have children and work in manufacturing, construction, or another profession that involves heavy metal exposure, bathe and change clothes immediately after work to avoid contaminating your home with heavy metals in dust, dirt, etc.
Strategies for the treatment of heavy metal toxicity in children
Research indicates that detoxification and excretory pathways responsible for detoxifying heavy metals may be impaired in children with behavioral disorders. (24) However, by enhancing detoxification pathways, replenishing essential minerals and vitamins, and supplementing with probiotics, it may be possible to alleviate heavy metal toxicity and reduce symptoms in children with behavioral disorders.
Support the glutathione pathway
The glutathione pathway is a crucial system in the body for detoxifying mercury and other heavy metals. Glutathione, often referred to as the “master antioxidant,” binds to heavy metals and facilitates their removal from the body. Research has found that ASD patients have lower glutathione levels than controls, a problem that may promote the retention of heavy metals in the body. (25) Oral and transdermal glutathione supplementation raises plasma glutathione levels in the blood of autistic children, an effect that may facilitate heavy metal detoxification. (26)
Replenish essential minerals and vitamins
When the body is deficient in essential minerals, heavy metals preferentially bind to sites normally occupied by those minerals. Replenishing the body with essential minerals can, therefore, help prevent heavy metal accumulation and increase metal excretion.
- Selenium. Selenium, an essential mineral that serves as a cofactor for the enzyme glutathione peroxidase, may benefit children with autism. (27)
- Zinc. Another essential mineral, zinc, alleviates heavy metal toxicity by competing with heavy metals for binding sites on cells and enzymes. Research indicates that zinc replenishment is beneficial for kids with autism and ADHD. (28) To replenish zinc levels, I suggest feeding your children zinc-rich foods, such as oysters, rather than zinc supplements, which may not be safe for children over the long term.
- Iron. Iron competes with heavy metals for intestinal absorption, and iron sufficiency downregulates transporters that bring heavy metals into intestinal cells and the systemic circulation. Restoration of iron levels has been found to relieve ADHD symptoms in children. (29) I recommend feeding your kids organ meats and shellfish to ensure optimal iron levels.
- Vitamin B. Replenishment of vitamin B6 may also alleviate heavy metal toxicity. B6 supplementation reduces the accumulation of lead in body tissues. When combined with magnesium, it has been found to improve symptoms of ADHD. (30, 31) The top dietary sources of vitamin B6 are liver and other organ meats, egg yolks, nuts, bananas, and avocados. (32)
The power of probiotics
Several studies indicate that probiotics alleviate heavy metal toxicity. Research indicates that Lactobacillus rhamnosus and L. plantarum, commonly found in probiotic supplements and fermented foods, protect against heavy metal toxicity. (33, 34) These findings also suggest that a healthy gut microbiome may protect against heavy metal toxicity.
Chelation therapy: Use with caution
Chelation therapy involves the use of synthetic chelating agents such as CaNa2 EDTA and DMSA and may be necessary to remove certain metals like lead. However, there are significant concerns about the safety and efficacy of chelation. Chelation depletes essential minerals and has the potential to redistribute heavy metals within the body. These effects may be especially harmful to children. For this reason, chelation should only be done under the guidance of a qualified healthcare professional. Avoidance of heavy metals and the use of nutritional detoxification strategies such as those mentioned above may be a gentler and safer method for reducing a child’s heavy metal burden.
Now I want to hear from you. Do you have a child with a behavioral disorder? Do you think heavy metals might be impacting your child’s health and behavior? What strategies have you tried for treating heavy metal toxicity? Let me know in the comments below.