A toxin is a poison made by living cells or organisms. Toxins can cause health problems on contact or when they are absorbed by the body.

The severity of a reaction to a toxin varies greatly. A bee sting causes a minor reaction in most people. Botulinum toxin can cause a deadly reaction. Usually, the severity of the health problem caused by a toxin depends on:

• How often a person is exposed to the toxin.
• How much toxin was in contact with or absorbed by the body.

Treatment can be as simple as staying away from the toxin and limiting future exposure. In some cases, serious illnesses such as cancer, heart disease, and lung disease can develop after long-term and repeated exposures. Some people with long-term exposure need major treatment, depending on the type of illness.

Fortunately, the levels of most toxins in the environment are low.