The term “heavy metals” refers to elements of specific weight characteristics. Toxic heavy metals are, unfortunately, present in our air, water, soil, and food supply as a byproduct of our industrialized society. In fact, contamination is so pervasive in our environment that it is no longer a question of whether one has been exposed to toxins, but rather the level of exposure. People who have acute toxicity from heavy metals – such as lead, mercury, arsenic, and cadmium – may exhibit obvious and classical symptoms of poisoning. But toxicity from chronic low-level exposure is much more insidious in its presentation. Chronic low-level exposure can lead to a wide array of problems, ranging from neuropsychiatric disturbances such as aggressive behavior, memory loss, depression, irritability, and learning deficits, to physical manifestations such as liver and kidney dysfunction, fatigue, infertility, gout, hypertension, headache, and candida (yeast) infections.
Even though efforts are under way to curb the output of toxins and heavy metals into the environment, the problem is far from being resolved. Today, even in the United States, thousands of tons of toxic industrial wastes, including heavy metals, are dumped into the environment every year. We are left with a legacy of years of industrial pollution and toxic substance use that haunts us to this day. Perhaps the two most widespread and significant heavy metal toxins are mercury and lead.
It is estimated that about 64 million homes in the United States still contain lead paint and that 5 to 15 million of these have been identified as “very hazardous” by the U.S. Department of Housing and Urban Development. According to the EPA, an estimated 1.7 million children are currently affected by lead toxicity in United States, and almost 900,000 of all children affected are under the age of six. This statistic is very important because the symptoms of lead poisoning in children are strikingly similar to several psychiatric “diseases” that are on the rise in the U.S. Children with high lead levels can exhibit lower IQ scores, learning disabilities, hyperactivity, aggressive or disruptive behavior, and difficulty maintaining attention. A child exhibiting this type of behavior today would likely be sent to a doctor’s office, diagnosed with attention deficit disorder, and promptly started on Ritalin or other psychoactive drugs.
Children with high lead levels are much more likely to drop out of school, have reading disabilities, and exhibit criminal behavior. Herbert Needleman, M.D., a professor of psychiatry and pediatrics at the University of Pittsburgh, conducted a study of nearly 2,000 children in Boston. He found that girls with elevated levels of lead were more likely to be dependent, to be poor at concentration, and to “display an inflexible and inappropriate approach to tasks,” while boys were more likely to have difficulty with simple directions and sequences of directions. Dr. Needleman concluded: “…Our findings would appear to add to the weight of evidence that even a lower level of exposure to lead, or its correlates, place children at increased risk of difficulties in school.”
It is important to note that childhood exposure to lead can result in adverse effects well into adulthood. A study by Stokes, et al, showed that a group of 281 young adults who had been exposed to lead as children showed significant adverse neurobehavioral effects 20 years after environmental exposure. While lead has been eliminated from the nation’s gasoline supply, the major source of contamination is lead-based paint, which was composed of up to 50% lead. Flakes and microscopic dust from the paint continue to contaminant homes for many years, and can be released in larger amounts during renovations. Additional sources of lead include water pipes, pesticides, factory emissions, cosmetics, and some folk remedies.
In addition to being a cellular toxin, lead competes with calcium in the body, which can cause various malfunctions in calcium metabolism including a decrease in neurotransmitter (chemicals that relay messages along nerve cells) release and blockade of calcium channels. The central nervous system appears to be affected to the greatest degree by lead toxicity, and this can explain the many neuropsychiatric symptoms associated with exposure to this heavy metal.
Why are some people more susceptible to heavy metal toxicity than others? One must always remember that each individual has a unique physiology, and may have an inherently strong or weak detoxification system to handle heavy metal exposure. In addition, poor nutrition, such as iron or calcium deficiency, has been shown to exacerbate the symptoms of lead exposure.