Environmental toxicology is the scientific study of the health effects of exposu
Environmental toxicology is the scientific study of the health effects of exposure to toxic chemicals (Table 1) occurring in the natural, work, and living environments. The term also describes the management of environmental toxins and toxicity and the development of protections for humans and the environment.
| 2013 RANK |
NAME |
| 1 | ARSENIC |
| 2 | LEAD |
| 3 | MERCURY |
| 4 | VINYL CHLORIDE |
| 5 | POLYCHLORINATED BIPHENYLS |
| 6 | BENZENE |
| 7 | CADMIUM |
| 8 | BENZO(A)PYRENE |
| 9 | POLYCYCLIC AROMATIC HYDROCARBONS |
| 10 | BENZO(B)FLUORANTHENE |
| 11 | CHLOROFORM |
| 12 | AROCLOR 1260 |
| 13 | DDT, P, P’- |
| 14 | AROCLOR 1254 |
| 15 | DIBENZO(A,H)ANTHRACENE |
| 16 | TRICHLOROETHYLENE |
| 17 | CHROMIUM, HEXAVALENT |
| 18 | DIELDRIN |
| 19 | PHOSPHORUS, WHITE |
| 20 | HEXACHLOROBUTADIENE |
Routes of Exposure to Chemicals
In order to cause health problems, chemicals must enter your body. There are three main “routes of exposure,” or ways a chemical can get into your body.
- Breathing (inhalation): Breathing in chemical gases, mists, or dust in the air.
- Skin or eye contact: Getting chemicals on the skin or the eyes. They can damage the skin or be absorbed through the skin into the bloodstream.
- Swallowing (ingestion): This can happen when chemicals have spilled or settled onto food, beverages, cigarettes, beards, or hands.
Once chemicals have entered your body, some can move into your bloodstream and reach internal “target” organs, such as the lungs, liver, kidneys, or nervous system.
What Forms Do Chemicals Take?
Chemical substances can take a variety of forms. They can be solids, liquids, dust, vapors, gases, fibers, mists, and fumes. The form a substance is in has a lot to do with how it gets into your body and what harm it can cause. A chemical can also change forms. For example, liquid solvents can evaporate and give off vapors you can inhale. Sometimes chemicals are in a form that can’t be seen or smelled, so they can’t be easily detected.
What Health Effects Can Chemicals Cause?
An acute effect of a contaminant (The term “contaminant” means hazardous substances, pollutants, pollution, and chemicals) is one that occurs rapidly after exposure to a large amount of that substance. A chronic effect of a contaminant results from exposure to small amounts of a substance over a long period of time. In such a case, the effect may not be immediately obvious. Chronic effects are difficult to measure, as the effects may not be seen for years. Long-term exposure to cigarette smoking, low-level radiation exposure, and moderate alcohol use are all thought to produce chronic effects.
Scientists have known that just about any substance is toxic in sufficient quantities for centuries. For example, small amounts of selenium are required by living organisms for proper functioning, but large amounts may cause cancer. The effect of a certain chemical on an individual depends on the dose (amount) of the chemical. This relationship is often illustrated b