The heavy metals most commonly associated with poisoning of humans are lead, mercury, arsenic and cadmium. Heavy metal poisoning may occur as a result of industrial exposure, air or water pollution, foods, medicines, improperly coated food containers, or the ingestion of lead-based paints.

General Discussion

Heavy metal poisoning is the accumulation of heavy metals, in toxic amounts, in the soft tissues of the body. Symptoms and physical findings associated with heavy metal poisoning vary according to the metal accumulated. Many of the heavy metals, such as zinc, copper, chromium, iron and manganese, are essential to body function in very small amounts. But, if these metals accumulate in the body in concentrations sufficient to cause poisoning, then serious damage may occur. The heavy metals most commonly associated with poisoning of humans are lead, mercury, arsenic and cadmium. Heavy metal poisoning may occur as a result of industrial exposure, air or water pollution, foods, medicines, improperly coated food containers, or the ingestion of lead-based paints. There are detoxification options however.

Signs & Symptoms

The symptoms of heavy metal poisoning vary according to which type of metal overexposure is involved. Some specific examples are:

ARSENIC POISONING

Arsenic is used in the manufacture of pesticides. The gas from arsenic also has some industrial uses. Overexposure may cause headaches, drowsiness, confusion, seizures, and life-threatening complications. Neurological symptoms include brain damage (encephalopathy), nerve disease of the extremities (peripheral neuropathy), pericapillary hemorrhages within the white matter, and loss or deficiency of the fatty coverings (myelin) around these nerve fibers (demyelination). Skin problems include transverse white bands on the fingernails (mees’ lines) and excessive accumulation of fluid in the soft layers of tissue below the skin (edema). Some individuals may experience a garlic-like odor that may be detectable on the breath.

Inorganic arsenic accumulates in the liver, spleen, kidneys, lungs, and gastrointestinal tract. It then passes through these sites but leaves a residue in tissues such as skin, hair, and nails. Symptoms of acute inorganic arsenic poisoning include severe burning of the mouth and throat, abdominal pain, nausea, vomiting, diarrhea, low blood pressure (hypotension), and muscle spasms.).

CADMIUM POISONING

Cadmium is used for many items, including electroplating, storage batteries, vapor lamps and in some solders. The onset of symptoms may be delayed for two to four hours after exposure. Overexposure may cause fatigue, headaches, nausea, vomiting, abdominal cramps, diarrhea, and fever. In addition, progressive loss of lung function (emphysema), abnormal buildup of fluid within the lungs (pulmonary edema), and breathlessness (dyspnea) may also be present. In some cases, affected individuals may exhibit increased salivation; yellowing of the teeth; an unusually rapid heart beat (tachycardia); low levels of iron within the red blood cells (anemia); bluish discoloration (cyanosis) of the skin and mucous membranes due to insufficient oxygen supply to these tissues; and/or an impaired sense of smell (anosmia).

CHROMIUM POISONING

Chromium is used in the manufacture of cars, glass, pottery and linoleum. Exposure to too much chromium may cause lung and respiratory tract cancer as well as kidney diseases. In addition, overexposure to chromium may also cause gastrointestinal symptoms, such as diarrhea and vomiting, often with blood. Symptoms may lead to severe water-electrolyte disorders, increased mild acidity of blood and body tissues (acidosis), and/or inadequate blood flow to its tissues resulting in shock. Lesions on the kidneys, liver, and muscular layer of the heart (myocardium) may also develop.

COBALT POISONING

Cobalt, used in making jet engines, may cause nausea, vomiting, lack of appetite (anorexia), ear ringing (tinnitus), nerve damage, respiratory diseases, an unusually large thyroid gland (goiter), and/or heart and/or kidney damage.

LEAD POISONING

Lead production workers, battery plant workers, welders and solders may be overexposed to lead if proper precautions are not taken. Lead is stored in the bone but may affect any organ system. The effects of lead poisoning varies depending on the age of the individual and the amount of exposure.

In adults, overexposure to lead may cause high blood pressure and damage to the reproductive organs. Additional symptoms may include fever, headaches, fatigue, sluggishness (letheragy), vomiting, loss of appetite (anorexia), abdominal pain, constipation, joint pain, loss of recently acquired skills, incoordination, listlessness, difficulty sleeping (insomnia), irritability, altered consciousness, hallucinations, and/or seizuresLead is excreted in urine and feces. However, it may also appear in hair, nails, sweat, saliva, and breast milk.

MANGANESE POISONING

Manganese is used as a purifying agent in the production of several metals. Symptoms associated with overexposure to manganese may include damage to the central nervous system and pneumonia. Additional symptoms and physical findings include weakness, fatigue, confusion, hallucinations, odd or awkward manner of walking (gait), muscle spasms (dystonia), rigidity of the trunk, stiffness, awkwardness of the limbs, tremors of the hands, and psychiatric abnormalities.

MERCURY POISONING

Mercury is used by dental assistants and hygienists, and chemical workers. Mercury can affect the lungs, kidneys, brain, and/or skin. Symptoms of mercury poisoning include fatigue, depression, sluggishness (letheragy), irritability, and headaches. Respiratory symptoms associated with inhalation to mercury vapors include coughing, breathlessness (dyspnea), tightness or burning pain in the chest, and/or respiratory distress. Some affected individuals may experience abnormal buildup of fluid in the lungs (pulmonary edema); pneumonia; and/or abnormal formation of fibrous tissue (fibrosis).

There may be behavioral and neurological changes associated with overexposure to mercury poisoning, such as excitability and quick-tempered behavior, lack of concentration, and loss of memory. Shock and permanent brain damage may also be result from mercury poisoning. Some affected individuals experience mental confusion. A progressive cerebellar syndrome with impaired ability to coordinate voluntary movements (ataxia) of the arms may also be present.

Mercury is mainly excreted through the urine and feces.

PHOSPHORUS POISONING

Symptoms associated with phosphorus poisoning include weakness, headaches, vomiting, sweating, abdominal cramps, salivation, wheezing secondary to bronchial spasm, drooping of the upper eyelids (ptosis), contraction of the pupil (miosis), and/or muscular weakness and twitching. In addition, non-inflammatory degenerative disease of the sensorimotor nerves (sensorimotor polyneuropathy) may advance to progressive deterioration (atrophy). In some cases, respiratory paralysis may also occur.

THALLIUM POISONING

Symptoms associated with thallium poisoning include extreme drowsiness (somnolence), nausea, vomiting, abdominal pain, and bloody vomiting (hematemesis). Some affected individuals may experience the loss of most or all of their scalp hair (alopecia); rapidly progressive and painful sensory polyneuropathy; motor neuropathy; cranial nerve palsies; seizures; impaired ability to coordinate voluntary movements (cerebellar ataxia); and/or mental retardation. Some individuals may experience eye symptoms including wasting away (atrophy) of the optic nerve (optic atrophy), inflammation of the optic nerve (retrobulbar neuritis), and impaired functioning of the muscles of the eyes (ophthalmoplegia). In some cases, thallium poisoning may progress to include renal and cardiac failure, confusion, psychosis, organic brain syndrome, and/or coma.

ADDITIONAL METAL POISONINGS

Additional metals that may cause poisoning include antimony, aluminum, barium, bismuth, copper, gold, iron, lithium, platinum, silver, tin, and zinc. Common symptoms of poisoning from these metals may include gastrointestinal, renal, and neurological symptoms, such as headaches, irritability, psychosis, stupor, coma, and convulsions.

Antimony is used for hardening lead, and in the manufacture of batteries and cables. It may possibly cause lung disease and skin cancer, especially in those who smoke.

Copper is used in the manufacture of electrical wires. It may cause a flu-like reaction called metal fume disease and disturbances in the blood.

Lithium is used to make glasses and pharmaceuticals. Lithium may cause diseases of the stomach, intestinal tract, central nervous system, and kidneys.

Overexposure to silver may cause a gray discoloration of the skin, hair and internal organs. Additional symptoms may include nausea, vomiting, and diarrhea.

Zinc overexposure may cause the flu-like symptoms of metal fume fever; stomach and intestinal disturbances; and/or liver dysfunction.

Overexposure to bismuth may cause extreme drowsiness (somnolence) and neurologic disturbances such as confusion, difficulty in concentration, hallucinations, delusions, myoclonic jerks, tremors, seizures, an impaired ability to coordinate voluntary movements (ataxia), and/or inability to stand or walk.

Overexposure to gold (as in treatment of rheumatoid arthritis) may cause skin rashes; bone marrow depression; stomach and intestinal bleeding; headaches; vomiting; focal or generalized continuous fine vibrating muscle movements (myokymia); and yellowing of the skin, mucous membranes, and whites of the eyes (jaundice).

Some cases of overexposure to nickel have been associated an increased risk of lung cancer.

Overexposure to selenium may cause irritation of the respiratory system, gastrointestinal tract, and eyes; inflammation of the liver; loss of hair (alopecia); loss of skin color (depigmentation); and peripheral nerve damage.

Overexposure to tin may damage the nervous system and cause psychomotor disturbances including tremor, convulsions, hallucinations, and psychotic behavior.

Aluminum containers used in the manufacture and processing of some foods, cosmetics and medicines, and also for water purification. Overexposure to aluminum may cause brain damage (encephalopathy).