4. Lead (CAS# 7439-92-1)
Sources of exposure: Lead is the 5th most utilized metal in the U.S. It is mined extensively in Missouri Colorado Idaho and Utah and is used for the production of ammunition bearing metals brass materials solder ballasts tubes containers gasoline products ceramics and weights . Human exposure to lead occurs primarily through drinking water airborne lead-containing particulates and lead-based paints. Several industrial processes create lead dust/fumes resulting in its presence in the air. Mining smelting and manufacturing processes the burning of fossil fuels (especially lead-based gasoline) and municipal waste and incorrect removal of lead-based paint results in airborne lead concentrations. After lead is airborne for a period of ten days it falls to the ground and becomes distributed in soils and water sources (fresh and salt water surface and well water and drinking water). However the primary source of lead in drinking water is from lead-based plumbing materials .  The corrosion of such materials will lead to increased concentrations of lead in municipal drinking water. Lead from water and airborne sources have been shown to accumulate in agricultural areas leading to increased concentrations in agricultural produce and farm animals . Cigarette smoke is also a significant source of lead exposure; people whom smoke tobacco or breathe in tobacco smoke may be exposed to higher levels of lead than people whom are not exposed to cigarette smoke .

Target tissues: Lead is absorbed into the body following inhalation or ingestion. Children absorb lead much more efficiently than adults do after exposure and ingested lead is more readily absorbed in a fasting individual. Over 90% of inhaled lead is absorbed directly into the blood. After lead is absorbed into the body it circulates in the blood stream and distributes primarily in the soft tissues (kidneys brain and muscle) and bone. Adults distribute about 95% of their total body lead to their bones while children distribute about 73% of their total body lead to their bones 

Signs and Symptoms: Lead is one of the most toxic elements naturally occurring on Earth. High concentrations of lead can cause irreversible brain damage (encephalopathy) seizure coma and death if not treated immediately .  The Central Nervous System (CNS) becomes severely damaged at blood lead concentrations starting at 40mcg/dL causing a reduction in nerve conduction velocities and neuritis (ATSDR 1993). Neuropsychological impairment has been shown to occur in individuals exposed to moderate levels of lead. Evidence suggests that lead may cause fatigue irritability information processing difficulties memory problems a reduction in sensory and motor reaction times decision making impairment and lapses in concentration. At blood concentrations above 70 mcg/dL lead has been shown to cause anemia characterized by a reduction in hemoglobin levels and erythropoiesis-- a shortened life span of red blood cells. 

In adults lead is very detrimental to the cardiovascular system. Occupationally exposed individuals tend to have higher blood pressure than normal controls  and are at an increased risk for cardiovascular disease myocardial infarction and stroke. The kidneys are targets of lead toxicity and prone to impairment at moderate to high levels of lead concentrations. Kidney disease both acute and chronic nephropathy is a characteristic of lead toxicity. Kidney impairment can be seen in morphological changes in the kidney epithelium increases in the excretion rates of many different compounds reductions in glomerular filtration rate progressive glomerular arterial and arteriolar sclerosis and an altered plasma albumin ratio. Chronic nephropathy has lead to increased death rates among occupationally exposed individuals as compared to controls in studies by Selevan et al. (1975) and Cooper et al. (1985). Other signs/symptoms of lead toxicity include gastrointestinal disturbances abdominal pain cramps constipation anorexia and weight loss-immunosuppression and slight liver impairment .

Children are susceptible to the most damaging effects of lead toxicity. Ample literature shows just how damaging lead is to children. Prenatal and postnatal developments are compromised significantly by the presence of lead in the body. At blood lead concentrations of 80-100 mcg/dL severe encephalopathy occurs. Those children who survive lead-induced encephalopathy typically suffer permanent brain damage marked by mental retardation and numerous behavioral impairments. These children also suffer slower neural conduction velocities peripheral neuropathy cognitive impairment and personality disorders. Tuthill (1996) has found that hair lead levels in children were positively correlated with attention-deficit and hyperactive behavior. Numerous studies have implicated lead as a causal agent in the deterioration of cognitive functioning in children. 

Studies have shown IQ deficits in children with blood lead concentrations from 6-70 mcg/dL. Longitudinal studies have given further evidence that lead affects intelligence in exposed children. Studies have shown decreased performance on intelligence tests in lead exposed school children. One study has correlated lower socio-economic status with childhood lead poisoning 50 years after lead exposure . Maternal blood lead concentrations and prenatal lead exposure appear to be strong predictors of cognitive performance in offspring. Prenatal exposure may also cause birth defects miscarriage spontaneous abortion and underdeveloped babies. Lead not only appears to affect cognitive development of young children but also other areas of neuropsychological function. Young children exposed to lead may exhibit mental retardation learning difficulties shortened attention spans (ADHD) increased behavioral problems (aggressive behaviors) and reduced physical growth. Lead has been determined by many health experts to be the #1 threat to developing children in our industrial societies.

Medical test for lead screening: Blood urine and hair.

5. Mercury (CAS#7439-97-6)
Sources of exposure: Mercury occurs primarily in two forms: organic mercury and inorganic mercury. Inorganic mercury occurs when elemental mercury is combined with chlorine sulfur or oxygen. Inorganic mercury and elemental mercury are both toxins that can produce a wide range of adverse health affects. Inorganic mercury is used in thermometers barometers dental fillings batteries electrical wiring and switches fluorescent light bulbs pesticides fungicides vaccines paint skin-tightening creams vapors from spills antiseptic creams pharmaceutical drugs and ointments (ATSDR 1989a). Inorganic mercury vapor is at high concentrations near chlorine-alkali plants smelters municipal incinerators and sewage treatment plants. The organic form occurs when mercury is combined with carbon.

The most common form of organic mercury is methyl mercury which is produced primarily by small organisms in water and soil when they are exposed to inorganic mercury. Humans also have the ability to convert inorganic mercury to an organic form once it has become absorbed into the bloodstream. Organic mercury is known to bioaccumulate -- or passes up the food chain due an organism's inability to process and eliminate it. It is found primarily in marine life (fish) and can often be found in produce and farm animals processed grains and dairy products and surface salt- and fresh water sources . Occupational exposure to mercury containing compounds presents a significant health risk to individuals. Dentists, painters, fisherman, electricians, pharmaceutical/laboratories workers, farmers, factory workers, miners, chemists and beauticians are just some of the professions chronically exposed to mercury compounds.

Target tissues: The absorption and distribution of mercury compounds depends largely upon its chemical state. Organic mercury compounds are absorbed from the gastrointestinal tract more readily than inorganic mercury compounds with the latter being very poorly absorbed. After absorption in the gastrointestinal tract organic mercury is readily distributed throughout the body but tends to concentrate in the brain and kidneys. Approximately 80% of mercury vapor is absorbed directly through the lungs and distributed primarily to the CNS and the kidneys . Inorganic and organic forms of mercury have also been seen in the red blood cells liver muscle tissue and gall bladder 

Signs and symptoms: Mercury exposure can result in a wide variety of human health conditions. The degree of impairment and the clinical manifestations that accompany mercury exposure largely depend upon its chemical state and the route of exposure. While inorganic mercury compounds are considered less toxic than organic mercury compounds (primarily due to difficulties in absorption) inorganic mercury that is absorbed is readily converted to an organic form by physiological processes in the liver.

The acute ingestion of inorganic mercury salts may cause gastrointestinal disorders such as abdominal pain vomiting diarrhea and hemorrhage . Repeated and prolonged exposure has resulted in severe disturbances in the central nervous system gastrointestinal tract kidneys and liver. Davis reported dementia colitis and renal failure in individuals chronically poisoned due to the ingestion of an inorganic mercury containing laxative. Inhaled inorganic mercury can cause a wide range of clinical complications in individuals including corrosive bronchitis interstitial pneumonitis renal disorders fatigue insomnia loss of memory excitability chest pains impairment of pulmonary function and gingivitis.

Chronic inhalation of inorganic mercury compounds may result in a reduction of sensory and motor nerve function depression visual and/or auditory hallucinations muscular tremors sleep disorders alterations in autonomic function (heart rate blood pressure reflexes) impaired visuomotor coordination speech disorders dementia coma and death have shown that a group of dentists exposed to mercury vapors occupationally perform significantly worse in neurobehavioral tests that measure motor speed visual scanning visuomotor coordination and concentration verbal memory and visual memory. Kishi have found that smelter workers exposed to inorganic mercury compounds continue to experience neurological symptoms-tremors headaches slurred speech-senile symptoms and diminished mental capacities eighteen years after the cessation of mercury exposure. 

Our understanding of the effects of methyl mercury poisoning comes primarily from epidemic poisonings in Iraq and Japan. In Iraq more than 6000 individuals were hospitalized and 459 died as a result of methyl mercury poisoning. Adults experienced symptoms including parasthesia visual disorders ataxia fatigue tremor hearing disorders (deafness) and coma .Neuropathologic observations of exposed individuals have shown irreversible brain damage including neuronal necrosis cerebral edema gliosis and cerebral atrophy . Iraqi children poisoned through the consumption of methyl mercury containing food products (grains treated with mercury containing fungicides) exhibited nervous system impairment visual and auditory disorders weakness marked motor and cognitive impairment and emotional disturbances .

Individuals in Japan experienced many of these same symptoms after the ingestion of fish containing large amounts of methyl mercury. Similarly autopsies conducted on deceased Japanese in the Minamata Bay have shown pronounced brain lesions cerebral atrophy edema and gliosis in the deeper fissures (sulci) of the brain such as in the visual cortex . The Japan and Iraq epidemics have clearly established mercury as an agent that can disrupt developmental processes in the unborn and infantile individual. Methyl mercury can pass through the placental barrier and produce many deleterious effects on the unborn fetus.  Children born to mercury poisoned mothers were of smaller total weight had decreased brain weights at birth had fewer nerve cells in the cerebral cortex and experienced an abnormal pattern of neuronal migration . Of those children that survived the epidemic many experienced severe developmental effects like impaired motor and mental function hearing loss and blindness throughout their childhood .  Researchers have also observed a heightened incidence of cerebral palsy in children born to mothers in the Minamata Bay .

Mercury has recently been implicated as being a contributing factor to the increasing prevalence of autism in American children. The Autism Research Institute has focused on mercury containing vaccines (TMS) and their relationship to autism. Over 2 million individuals are affected with autism a neurodevelopment syndrome that typically produces impairment in sociality communication and sensory/perceptual processes and recent evidence has found a positive correlation between complications seen in autistics and complications seen in mercury poisoned individuals . While it is difficult to ascribe causation in this case it should not be altogether dismissed. Mercury poisoning has been implicated in the development of many other human dysfunctional states for many years. Among these are cerebral palsy amyotrophic lateral sclerosis Parkinson's disease psychosis and chronic fatigue syndrome .

We are beginning to understand the threat that heavy metal toxins are to our health. However heavy metal toxicity is a condition that often goes overlooked in traditional medical diagnoses. While it is rare for an individual to experience a disease or health condition solely from a heavy metal toxin it is reasonable to conclude that these toxins exert a dramatic effect on the health of an individual and contribute to the progression of many different debilitating conditions.

We have seen how just 5 heavy metals and their respective compounds can adversely affect an individual's health. These effects range from simple gastrointestinal disturbances to severe emotional and cognitive disturbances. Metal toxins have the ability to impair not just a single cell or tissue but many of the body's systems that are responsible for our behavior mental health and proper physiological functioning that we depend on for sustained life. If undetected these agents can cause immeasurable pain and suffering for any afflicted individual.

Heavy Metal Toxicity and Cardiovascular Conditions

Heavy metal toxicity is frequently the result of long term low level exposure to pollutants common in our environment: air water food and numerous consumer products. Exposure to toxic metals is associated with many chronic diseases. Recent research has found that even low levels of lead mercury cadmium aluminum and arsenic can cause a wide variety of health problems.

SYMPTOMS AND SOURCES OF HEAVY METAL POISONING.