The largest mass poisoning of a human population in history took place in Bangladesh. As a result, 35 million exposed people have lethal levels of arsenic. Mortality rates are estimated at 13 per 1000. This means that this poisoning has cost 455,000 lives.

It happened quite simply. In the late 1960s and 1970s, UNICEF and the World Bank, concerned that surface water in the area was causing too many fatal cases of diarrhea, funded the drilling of new wells. These deep wells provided an abundance of fresh water to the burgeoning population of Bangladesh and West Bengal.

The problem: They didn't test the new wells for heavy metal levels.

The negligence is hard to understand, but it is nothing compared to the global irresponsibility that happens every day in the world of large food manufacturers.

Exposure to heavy metals in food, air and water is perhaps the most underestimated toxicity issue of our time. The consequences of chronic exposure cannot be underestimated. The damage caused by exposure goes far beyond physical health. The brain is also poisoned.

This is the reality of heavy metal exposure and its toxicity. The following is evidence from scientific and case studies and research that shows how aluminum, copper, lead, mercury, cesium, cadmium and arsenic contribute to chronic poisoning of your brain.

Aluminium

According to New York University Langone Medical Center, symptoms of aluminum toxicity can include serious brain health problems, including:

• confusion
• speech impediments or problems with speech
• nervous system problems cause involuntary tics

It is feared that aluminum toxicity can lead to degenerative diseases such as: Alzheimer's and Parkinson's. Several studies have linked conditions of overexposure to aluminum to these diseases, including studies from the University of California, Belgrade University School of Medicine, and the School of Zoological Studies at Jiwaji University in India.

Natural health practitioners believe that aluminum accumulates in the thyroid, liver, lungs and brain. It is believed that overexposure to aluminum can lead to a number of symptoms, including confusion, memory loss and cognitive impairment. As a result, aluminum cleaning and approaches such as Metout are well known.

Copper

According to the National Institute of Health, overexposure to copper can cause a number of physical symptoms. Symptoms of copper toxicity that may be considered mental health problems are chills, convulsions, a metallic taste in the mouth and weakness.

Dr. Lawrence Wilson has also written extensively about copper toxicity syndrome. This condition is believed to cause a number of mental health symptoms, including:

• fatigue
• insomnia
• depression
• detachment from everything
• learning disabilities
• premenstrual syndrome
• Alzheimer's disease

Lead

Lead is a known neurotoxin and this has been scientifically studied. It is associated with major depression and anxiety disorders. It seems inevitable that if you have high levels of lead in your blood, you will suffer from cognitive and mood disorders.

Symptoms related to lead exposure:

• learning and memory decreased
• Reduced IQ
• diminished verbal ability
• speech and hearing disorders
• hyperactivity
• ADHD
• fatigue
• irritability
• lethargy
• difficulty in concentrating
• headaches
• encephalopathy

Mercury

The CDC reports that exposure to metallic mercury gas over a long period of time can cause irritability, sleep disturbances, excessive shyness, coordination problems, tremors, memory problems and mood swings.

Natural health practitioners know that mercury in children's vaccines and in the environment is one of the main causes of problems such as attention deficit hyperactivity disorder and autism spectrum disorders.

These symptoms include:

• lack of communication/connection with others
• hyperactivity
• difficulty in concentrating
• language delay
• reduced cognitive function
• decreased appetite
• sensitivity to environmental stimulation (light, sounds, smells)
• repetitive behaviors

Cesium

While it is suspected to be unusual for a person to be exposed to toxic amounts of cesium naturally, the CDC gives indications of cesium-related symptoms such as decreased mental capacity and increased or decreased activity.

Many natural health practitioners are not aware that exposure to cesium through food or drink could be a likely cause of disorders such as ADHD, and difficulty concentrating.

Cadmium

The New York University of Medicine does not list any mental health symptoms associated with cadmium exposure and toxicity. However, many authors consider that cadmium associated with heavy metals such as zinc and mercury, can cause the same symptoms as those associated with heavy metal toxicity:

• anxiety and irritability
• difficulty concentrating, or "brain fog
• depression
• fatigue
• insomnia
• memory loss or forgetfulness

Arsenic

Arsenic poisoning can be fatal if left untreated. Exposure to toxic levels can occur in a number of instances, including consumption of contaminated food and beverages. Living in industrial areas can also increase exposure rates, and arsenic can be found in contaminated drinking water. Arsenic poisoning can lead to a number of obvious mental health symptoms, including:

• confusion
• drowsiness
• headaches
• convulsions
• night blindness

Arsenic poisoning can progress if not treated promptly, and unusual symptoms should be treated immediately. The most sinister aspect of chronic heavy metal exposure and toxicity is that it cannot be easily detected. You can't know for sure unless you test.