Lead poisoning

Lead (Pb) is a natural component of the earth's crust with trace amounts existing in soil, water and plants. It has many uses, including in the manufacture of lead-acid batteries for motor vehicles and energy storage, in pigments and paints, solder, ammunition, ceramic glazes, jewelry, toys and also in some cosmetics and traditional medicines.

Lead is the most important toxic heavy element in the environment. Globally it is an abundantly distributed, important yet dangerous environmental chemical. According to WHO lead poisoning refers to excessive human exposure to lead.

Lead enters the body via ingestion or inhalation from sources such as soil, food, lead dust and contact with lead in products of everyday use and in the workplace. In the work environment, the main route of absorption of Pb and its compounds is through the respiratory system, although lead is also absorbed via the digestive system.

Lead has been used for thousands of years and its poisoning effects have been recognized for several centuries. Leaded gasoline and paints were thought to be the main sources of lead pollution in the environment.

Though its widespread use has discontinued in many countries of the world, it is still used in many industries like car repair, battery manufacturing and recycling, refining, smelting, etc. Lead is a highly poisonous metal affecting almost every organ in the body.

Lead has no biological function in the body. It accumulates in the body and affects practically all organ systems. Long-time exposure to lead has been reported to cause anemia, along with an increase in blood pressure, and that mainly in old and middle-aged people.

Lead exposure can cause chronic and debilitating health impacts in all age groups, but it is particularly harmful to young children. This is because the developing nervous system is vulnerable to the toxic effects of lead, even at levels of exposure that do not cause obvious symptoms and signs.
Lead poisoning

Mercury toxicity

Toxic elements, such as mercury and methylmercury, are neurological toxicants to humans. Mercury exposure is associated with slow mental development, blindness, cerebral palsy, and other birth defects in human. The target organ for inhaled mercury vapor is primarily the brain. Mercurous and mercuric salts chiefly damage the gut lining and kidney, while methyl mercury is widely distributed throughout the body.

Mercury is 1 of 2 elements (bromine is the other) that are liquid at room temperature. Its elemental symbol is Hg, derived from the Greek word hydrargyrias, meaning “water silver.”

Mercury does not play an important role in terrestrial food chains, but it is always detected in marine organisms. While plant‐based foods usually contain only trace amounts of inorganic mercury, fish and seafood are the main sources of mercury exposure for humans. Fish at the top of the food chain (e.g., tuna, swordfish, or shark) may concentrate considerable mercury in their tissues.

Mercury contamination in fish and seafood is predominantly in the organic form of methylmercury that is produced by marine microorganisms.

Mercury in any form is toxic. Mercury poisoning can result from vapor inhalation, ingestion, injection, or absorption through the skin. Inhaled elemental mercury vapor, for example, is easily absorbed through mucus membranes and the lung and rapidly oxidized to other forms.

Highly toxic and poisoning usually results due to accidentally or intentional ingestion. Mercury chloride listed as ‘Violent poison’ in the Merck’s Index in 1996. It is caustic in nature. When ingested lining of GI tract is lost, patient exhibits severe pain, nausea, vomiting and diarrhea.
Mercury toxicity

An element of mercury

Mercury is an element and a metal that is found in air, water, and soil. Mercury is a heavy metal from group 12 of the periodic table, along with Zn and Cd. Gold and Tl are its period neighbors.

The human health effects from exposure to low environmental levels of elemental mercury are unknown. Very high mercury vapor concentrations can quickly cause severe lung damage. At low vapor concentrations over a long time, neurological disturbances, memory problems, skin rash, and kidney abnormalities may occur.

In soil and in water, mercury can exist in either the monovalent or divalent forms as inorganic compounds. The particular valence state in which mercury exists in the environment (Hg0, Hg+, Hg2+) is dependent upon multiple factors, including the pH and redox potential of the particular medium and the strength of the ligands present.

Mercury is highly toxic to most forms of life. When eaten in large amounts, some inorganic mercury compounds can be very irritating and corrosive to the digestive system. If repeatedly eaten or applied to the skin over long period of time, some inorganic mercury compounds can cause effects similar to what is seen with long term mercury vapor exposure, including neurological disturbances, memory problems, skin rash, and kidney abnormalities.

Some organomercurials, in particular low-molecular-weight alkyl compounds, are considered even more toxic to humans because of their high chronic toxicity with respect to various, largely irreversible, defects of the neryous system.

An element of mercury

Chemical element: Lead

Toxic minerals are minerals that are hazardous to human health. A mineral by itself, or its components, can be toxic. Typical examples of the former are asbestos, selenium, and silica minerals; typical examples of the latter are minerals containing such toxic chemicals as arsenic, lead, mercury, or cadmium.

It is very soft, highly malleable, ductile, and a relatively poor conductor of electricity. It is very resistant to corrosion but tarnishes upon exposure to air.

Lead belongs to group 14 of the periodic table, which also includes C, Si, Ge and Sn. Lead has the most metallic characteristics of this group. The element has an atomic number of 82, an atomic mass of 207, two oxidation states (+2 and +4) and four naturally occurring isotopes (204Pb, 206Pb, 207Pb and 208Pb), of which 208Pb is the most abundant at 52% of the total mass.

The major use of lead today is for batteries. Lead also is used as a protective shield against radiation. One lead mineral that was historically used as a nat-ural dye is chrome yellow, which is toxic.

Lead is a heavy metal with a high toxicity. Lead is toxic at very low exposure levels and has acute and chronic effects on health and the environment. It can effect the nervous system, the reproductive system, and the heart and blood system. Minerals containing lead are toxic to many tissues and organs, including the heart, bones, intestines, kidneys, brain, and reproductive system. Also, lead ions inhibit enzymes neces-sary for the synthesis of hemoglobin (the oxygen car-rier in human blood). Lead poisoning causes mental retardation and neurological disorders.

Chemical element: Lead

Cadmium in food

Cadmium is a soft, ductile, silver-white metal that belongs together with zinc and mercury to group IIb in the Periodic Table. It has relatively low melting (320.9 °C) and boiling (765 °C) points and a relatively high vapor pressure.

Food is the primary source of cadmium exposure among general population as a consequence of the bio-concentration of cadmium from soil. Chronic cadmium exposure has been reported to be associated with chronic kidney disease, osteoporosis, diabetes, cardiovascular disease and cancer. Cadmium is toxic to the kidney, while exposure to high levels of tin from, e.g. canned food in incorrectly manufactured tins can cause gastrointestinal irritation and upsets.

According to the current knowledge kidney damage (renal tubular damage) is probably the critical health effect. Other effects of cadmium expo-sure are disturbances of calcium metabolism, hypercalciuria and formation of stones in the kidney.

It has also been associated with lung damage (including induction of lung tumours) and skeletal changes in occupationally exposed populations. Cadmium is relatively poorly absorbed into the body, but once absorbed is slowly excreted, like other metals, and accumulates in the kidney causing renal damage.

Cadmium is used to produce a wide variety of consumer and industrial materials, such as electrode in Ni-Cd batteries; pigments for plastics, ceramics, and glasses; stabilizers for polyvinyl chloride (PVC); coatings for steel and nonferrous metals; solar cells and electronic devices, and constituent of fungicides or fertilizers.

Drinking-water contains very low concentrations of cadmium, usually in the range 0.01–1 μg/liter.

For nonsmokers, food constitutes the principal environmental source of cadmium. The lowest concentrations are found in milk (around 1 μg/kg). The concentration of cadmium is in the range 1-50 μg/kg in meat, fish and fruit and 10-300 μg/kg in staple foods such as wheat, rice and potatoes.

The highest cadmium levels (100-1000 μg/kg) are found in the internal organs (kidney and liver) of mammals and in certain species of mussels, scallops and oysters. When grown on a cadmium-polluted soil, some crops, such as rice, can accumulate considerable amounts of cadmium (more than 1000 μg/kg).

Cadmium in food

Aluminium toxicity

Aluminium is the third most prevalent element and the most abundant metal in the earth's crust, representing approximately 8% of total mineral components.

The concentration of aluminium in food is extremely variable, due both to the original content and to food interaction with the material it contacts in storage or in cooking. For example, the aluminium content of a variety of beverages contained in aluminium cans is five to seven times higher compared to the same type of beverage from bottles.

Plants such as tea accumulate aluminium in older leaves, which may contain as much as 3 % w/w of aluminium, which explains the high aluminium concentrations in tea infusions. A high aluminium content has also been found in coffee beans, at levels comparable to those of tea leaves.

Aluminium's free metal cation, Al 3+ , is highly biologically reactive and biologically available aluminium is non-essential and essentially toxic. Biologically reactive aluminium is present throughout the human body and while, rarely, it can be acutely toxic, much less is understood about chronic aluminium intoxication.

Use of aluminium salts as coagulants in water treatment may lead to increased concentrations of aluminium in finished water. Where residual concentrations are high, aluminium may be deposited in the distribution system. Disturbance of the deposits by change in flow rate may increase aluminium levels at the tap and lead to undesirable colour and turbidity.
Aluminium toxicity

Copper toxicity

A number of biochemical processes depend on copper to function normally, plus copper is involved in the function of the nervous system. It is an essential component of iron utilization, connective tissue formation, pigmentation and enzymes used in energy production.

Although copper is one of the essential nutrients required by the human body for both physical and mental health, an excessive copper concentration in the human body becomes a toxic threat. Too much cooper in the system can cause a variety of ailments, including diarrhea, eczema, high blood pressure, kidney disease, nausea, premenstrual syndrome, sickle cell anemia, stomach pain and severe damage to the central nervous system.

The regular daily intake of 2 to 5 mg copper in adults is considered normal and thus free from harmful effects. Higher dosage, of 32 mg, can have an astringent effect and cause nausea; 80 to 132 mg may lead to vomiting.

Acute copper toxicity can result in number pathologies and, in severe cases, death. It can result from the ingestion of copper contaminated beverages including water or the accidental or liberate ingestion of high quantity of copper salts.
Copper toxicity

Iodine toxicity

Because high amounts of iodine inhibit synthesis of thyroid hormones and stimulate growth of the thyroid gland, iodine toxicity also can cause goiter. In other words, both too much and too little iodine cause goiter.

Overzealous supplementation is the most common cause of iodine toxicity.

High doses of free iodine, such as in form of iodine tincture, are highly toxic, if brought into body cavities, and cause swelling and bleeding of mucous membranes.
Iodine toxicity 

Biochemistry of zinc

Nutrition involves the relationship of food and nutrients to health. Biochemistry is the science of the chemistry of living organisms.

Zinc metalloenzymes catalyze approximately 50 important biochemical reactions. Many of these enzymes have been isolated from more than one species, resulting in identification of over 200 catalytically active zinc metalloproteins. Carbonic anhydrase, alcohol dehydrogenase, alkaline phosphatase and steroid hormone receptors are examples.

The functions of zinc in metalloenzymes are catalytic structural, regulatory and noncatalytics. Examples of enzymes in which zinc plays a catalytics role include carbonic ahnydrase, carboxypeptidas, thermolysin, and aldolases.

Excessive intake can cause adverse effects in humans and animals. In human, the effects of acute zinc toxicity are gastrointestinal disturbances giving rose to abdominal pain, nausea and vomiting. Chronic zinc toxicity is associated with changes in copper balance leading to symptoms of copper deficiency.

Zinc deficiency is an important part of protein-energy malnutrition and may limit weight gain during refeeding unless adequate amounts are provided.

The average daily dietary intake of zinc is around 150 umol. It is present in all protein rich foods.
Biochemistry of zinc

Manganese toxicity

Toxicity of manganese compounds appears to depend upon type of manganese ion presents and the oxidation state of manages.

It has been suggested that manganese cations are more toxic than the anion forms. In 1901 research showed that manganese toxicity could result in neurological damage in humans.

However, it was not until a series of reports in the 1930s and 1940s describing a high incidence of manganese toxicity in manganese mine workers that manganese toxicity was recognized as a significant health workers. Chronic inhalation exposure of humans to high levels may result in a syndrome called manganism and typically begins with feelings of weakness and lethargy and progresses to other symptoms such as gait disturbances, clumsiness, tremors, speech disturbances, a mask-like expression, and psychological disturbances.

Additionally, individuals with liver failure are at greater risk for toxicity because manganese homeostasis is maintained largely by the liver through excretion in the bile.

Manganese toxicity secondary to liver failure is characterized by manganese accumulation within the liver and other organs such as the brain; accumulation in the brain results in neurologic abnormalities.

Psychological changes including mental irritability, headaches, nervousness, compulsive actions, and hallucinations can occur.
Manganese toxicity 

Toxicity of zinc

In humans, most of the body’s zinc is in the skeletal muscle (about 60%) and one third in the bone, skin, liver, brain, kidneys and the heart have small total amounts in this regard. Excessive intakes of zinc cause toxicity.

Zinc has low human toxicity by the oral route, but high levels can cause gastrointestinal distress. An acute zinc toxicity (such as from 4 g of zinc gluconate, which provides 570 mg of elemental zinc) produces some of the following symptoms: metallic taste, headache, weak heart beat, nausea, vomiting, epigastric pain, abdominal cramps and bloody diarrhea.

Tachycardia, hemolytic anemia, pancreatitis, renal damage and death have been reported on this occasion.

Long term oral intakes of zinc at levels of 18,5 to 25 mg/day can interfere with copper absorption and intakes 10 to 30 items the RDA can impair immune responses and decrease serum high density lipoprotein.

The most common sources of zinc poisoning in human are metal fumes, and illness arising the ingestion of acidic foods prepared in zinc galvanized containers. The inhalation of zinc phosphide or phosphine gas also results in acute toxicity.
Toxicity of zinc

Copper excessive in human body

Trace amounts of copper are essential for the human body. Since copper is not manufactured the body, it must be taken in through the diet.

The human body copper at a level of about 1-3 mg/kg of body mass. Copper is absorbed in the gut and then transported to the liver. Copper is an essential micronutrient required to sustain life in humans and other organisms, but it also be toxic if present in excess.

Too much copper is the system can cause a variety of ailments, including diarrhea eczema, hemolytic anemia, high blood pressure, kidney disease, nausea, premenstrual syndrome, sickle cell anemia, stomach pain and severe damage to the central nervous system.

Excessive copper levels in the body can be toxic and can impair physical and mental health.  It has been linked to neurodegenerative diseases including Alzheimer’s, Menkes and Wilson’s disease.

Excessive copper in the body can promote destruction of eye tissue though oxidation. Persons with eye problems should be especially careful to balance their intake of copper with that of iron, zinc and calcium.

Studies have revealed that serum levels with either high copper and low magnesium or concomitance of low zinc with either high copper or low magnesium can both increase the mortality risk for middle-aged men.
Copper excessive in human body

Effects of selenium toxicity to human health

Selenium is probably the most toxic, weight for weight, of the essential nutrients. Very few instances of human selenium intoxication have been recorded.

Selenosis, a condition defined by blood selenium levels greater that 100 ug/dL, can result in symptoms including gastrointestinal upsets, hair loss, white blotchy, nail brittleness, garlic breath odor, fatique, irritability and mild nerve damage.

Acute poisoning of selenium is lethal, with damage occurring to most organ system. It produces central nervous system effects, such as nervousness, drowsiness and convulsions.

It has been observed both in miners and in people who consume excess selenium form supplements. 

Manifestations of selenium toxicity depend on dose and duration of exposure, on route of exposure and on the chemical form of selenium.

The most toxic forms of selenium are sodium, selenite, sodium selenate, selenomethionine, and selenodiglutathione.
Effects of selenium toxicity to human health

Manganese toxicity symptoms

Manganese is widely distributed in the biosphere: it constitutes approximately 0.085% of the Earth’s crust, making it the twelfth most abundant element. Exposure to high levels of oral, parental and air manganese may result in toxicity.

Manganese toxicity in humans is primary a concern for those exposed to high airborne concentration in the workplace, especially industrial workers and miners.

Severe neurological damage has been observed in inhabitants of Groote Eylandt, an island in the Gulf of Carpentaria off the north coasts of Australia which contains one of the world’s richest manganese mines.

In addition to neural damage, reproduction and immune dysfunction, nephritis, testicular damage, pancreatitis, lung disease, and hepatic damage can occur with manganese toxicity, though the frequency of these disorders in unknown. Manganese toxicity can result in a permanent neurological disorder known as manganese with symptoms that include tremor, difficulty walking and facial muscle spasms.

In the milder form, toxicity is expressed by hyperirritability, violent acts, hallucinations, disturbances of libido and coordination.

Cases of manganese toxicity in humans have reported only for adults; however, it has been suggested that infants may be at high risk for manganese toxicity due to a high absorptive capacity for the element and/or an immature excretory pathway for it.

Additionally, individuals with liver failure are at greater risk for toxicity because manganese homeostasis is maintained largely by lover though excretion in the bile.

The symptoms of manganese toxicity may appear slowly over months and years.
Manganese toxicity symptoms

Aluminum toxicity in humans

A majority of aluminum in plasma is bound to transferring. A smaller fraction of aluminum is probably complexed with citrate.

The average amount of aluminum in the human body is 65 milligrams but can range from 50 150 milligrams. 

The average person absorbs anywhere from 10 to 100 milligrams of aluminum every day through aluminum cookware, baking soda, antacids and numerous other sources.

Aluminum toxicity can lead to a number of ailments including constipation, colic, loss appetite, nausea, skin ailments, twitching of leg muscles, excessive perspiration and loss of energy.

Other symptoms: rickets, poor calcium metabolism, extreme nervousness, anemia, memory loss, softening and weakness of the bones and aching muscle.

The target organs for aluminum toxicity are primary the lungs, bones and the central nervous system.

Bone loss and increased intestinal absorption of aluminum and silicon combine to form compounds that accumulate in the cerebral cortex of the brain. These compounds prevent impulses from being carried to or from the brain.

Although cause of Alzheimer’s disease remains unclear, research indicates that aluminum toxicity may be one of the primary culprits.
Aluminum toxicity in humans

Tin toxicity

High concentration of tin in food irritate the gastrointestinal tract and may cause stomach upsets in some individuals. Delayed symptoms frequently develop 1-3 days after exposure, especially a nearly universal headache or other severe pain.

The symptoms include nausea, vomiting, diarrhea, abdominal cramps, abdominal bloating fever and headache. This usually occurs after ingestion of inorganic tin by eating food or drinking liquids from tin containers.

Proximal tubule epithelial degeneration is the major renal change observed in humans after inhalation of organotin compounds.

Tin corrosion occurs throughout the shelf life of the product. Aerosol exposure to tin occurs mostly in occupational settings with poor industrial hygiene.

This may cause coughing and shortness of breath. This cough may bring up mucus is lemon yellow and sweet tasting.

Tin toxicity may involve the inhibition of certain key enzymes. It is suggested that tin may inhibit the hydrolysis of adenosine triphosphate and uncouple oxidation phosphorylation in the mitochondria.
Tin toxicity

Cadmium in human diet

Food is recognized as the major source of cadmium in humans, except in comparatively rare cases of occupational air exposure. The recommended upper limit for cadmium in food is 75.0 ug/day.

It is widely distributed in nature: oyster, seafood, and grains are rich sources; it also can be obtained from air and the water supply.

About 6% of the cadmium ingested in food and beverages is absorbed by the human body. Higher dietary levels of calcium and protein need to increase cadmium absorption.

Most of the absorbed cadmium is retained in the kidneys bound to a metal-binding, high sulfhydryl protein, metallothionein.

The essentiality of cadmium in humans remains to be established. Nutritional requirements, if they exist, are very low and easily met by the levels in food and drinks.

There was a study that regular high doses of cadmium caused increased blood pressure, with pressure returning to normal when the cadmium treatment ceased.

Study also found elevated cadmium levels associated with atherosclerosis, an increase in heart size and reduced kidney function.

Cadmium in human diet

Cadmium toxicity

Cadmium is an inorganic metal that is naturally present in the environment. Like lead, cadmium accumulates in the body and has varying degrees of toxicity.

Cadmium can contaminate food by its presence in pesticides, pigments, plaints, plastics, and cigarettes.

Cadmium’s toxic effects are kept under control when balanced by adequate body stores of zinc.

The human body can tolerate low levels of cadmium, but long term chromic exposure can lead to serious health problems.

Hazardous cadmium levels lead to nephrotoxic effects, i.e. renal tubular dysfunction. Cadmium furthermore inhibits several SH-containing enzymes in the brain, while chronic cadmium exposure leads to reduced levels of norepinephrine, serotonin and acetylcholine.

High exposure has been linked to osteomalacia, a softening of the bones.

Cadmium is a potent antagonist of several essential minerals, including zinc, copper, iron and calcium.

Cadmium cam accumulate to toxic levels over a lifetime because the mineral is not well excreted by the human body. However cadmium is poorly absorbed, so normal dietary intake does not warrant concern for toxicity.

The absorption of cadmium from food varies, depending on genetic factors, age, and nutritional factors.

Infants absorb and accumulate more cadmium than adults.

Cadmium deposits in the kidneys, causing kidney tissue damage and high blood pressure or hypertension as well as calcium kidney stones.
Cadmium toxicity

Manganese

Manganese
The adult body contains about 20 mg of manganese, found mainly in the liver, pancreas pituitary gland and bone.

Although it is considered a dietary essential, manganese is also toxic at high levels.

Manganese functions like other trace elements as an essential part of cell enzymes that catalyze any important metabolic reactions.

Absorption and retention of manganese are associated with serum ferritin concentration.

Manganese deficiency is rare, but it has been reported in cases of diabetes and pancreatic insufficiency and in protein-energy malnutrition states such as kwashiorkor.

Manganese toxicity occurs as an industrial disease, inhalation toxicity, in miners and other workers with prolonged exposure to manganese dust.

The excess manganese accumulates in the liver and central nervous system, producing severe neuromuscular symptoms similar to those of Parkinson’s disease.

The best food sources of manganese are of plant origin. Whole grain, cereal products and teas are the richest food sources, and fruits and vegetables are somewhat less rich.

Dairy products, meat fish and poultry are poor sources of manganese.
Manganese