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Toxicology Health Article

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Role in human health

Humans are exposed to complex mixtures of chemicals, many of which are synthetic and have been either deliberately or accidentally released into the environment. In some cases, people actively expose themselves to chemicals that are known to be toxic, such as smoking cigarettes, drinking alcohol, or taking recreational drugs. Voluntary exposure to chemicals also occurs when people take medicines to deal with illness, or when they choose to work in an occupation that involves routinely dealing with dangerous chemicals. Most exposures to potentially toxic chemicals are inadvertent, and involve living in an environment that is contaminated with small concentrations of pollutants, such as those associated with pesticide residues in food, lead from gasoline combustion, or sulfur dioxide and ozone in the urban atmosphere.

Drugs given to improve health can lead to toxicity even when given in appropriate doses. Conditions such as dehydration and other forms of physiological compromise can make the patient more vulnerable to toxicity. Drugs like digoxin, lidocaine, and lithium are common examples of drugs with potentially toxic effects. Interactions of substances in the body may also produce toxic effects. For example, if two central nervous system depressants are taken at once, as in the case of combining alcohol and a tranquilizer, the effects are additive and could lead to extreme depression of the central nervous system functions.

The health care system's role related to toxicology includes education and prevention as well as treatment of both acute and chronic effects of toxins. Agencies such as the Food and Drug Administration (FDA) and the Occupational Safety and Health Administration (OSHA) work with health care and industry to offer guidelines and restrictions on the manufacture and use of pharmaceuticals, foods, and other substances.

Health care workers are involved by being aware of these regulations, and staying informed. They also provide education, such as, teaching new parents about the dangers of lead paint consumption by children, and help prevent exposure to toxins, such as, tetanus vaccination, or monitoring for signs of lithium toxicity. The Poison Control Center uses nurses and other allied health workers to inform the public of immediate actions to take in the event of a poisoning emergency. Emergency interventions at the hospital include blood and urine tests,

gastric lavage with administration of absorbent activated charcoal, and administration of antidotes when available.

Common diseases and disorders

Toxicologists have ranked the most commonly encountered toxic chemicals in the United States. In descending order of frequency of encounter, they are as follows:

Arsenic—Toxic exposure occurs mainly in the workplace, near hazardous waste sites, or in areas with high natural levels. A powerful poison, arsenic can, at high levels of exposure, cause death or illness.
Lead—Toxic exposure usually results from breathing workplace air or dust, or from eating contaminated foods. Children may be exposed to lead from eating lead-based paint chips or playing in contaminated soil. Lead damages the nervous system, kidneys, and the immune systems.
Mercury—Toxic exposure results from breathing contaminated air, ingesting contaminated water and food, and possibly having dental and medical treatments. At high levels, mercury damages the brain, kidneys, and developing fetuses.
Vinyl chloride—Toxic exposure occurs mainly in the workplace. Breathing high levels of vinyl chloride for short periods can produce dizziness, sleepiness, unconsciousness, and, at very high levels, death. Breathing vinyl chloride for long periods of time can give rise to permanent liver damage, immune reactions, nerve damage, and liver cancer.
Benzene—Benzene is formed in both natural processes and human activities. Breathing benzene can produce drowsiness, dizziness, and unconsciousness. Long-term exposure affects the bone marrow and can produce anemia and leukemia.
Polychlorinated biphenyls (PCBs)—PCBs are mixtures of chemicals. They are no longer produced in the United States, but remain in the environment. They can irritate the nose and throat, and cause acne and rashes. They have been shown to cause cancer in animal studies.
Cadmium—Toxic exposure to cadmium occurs mainly in workplaces where cadmium products are made. Other sources of exposure include cigarette smoke and cadmium-contaminated foods. Cadmium can damage the lungs, cause kidney disease, and irritate the digestive tract.