1. Classification based on particular effects on health
Types of Toxicants
Classification based on particular effects on health

2. Carcinogens Chemicals or types of radiation
Cause cancer - uncontrolled cell growth
Greatest # of cancer cases is thought be related to carcinogens in cigarette smoke

3. Mutagens Chemicals or types of radiation
Cause mutations in DNA sequence
E.g. UV rays, x-rays, nitrous acids

4. Teratogens
Chemicals
Affect the development of human embryos in the womb
Cause birth defects
e.g. thalidomide – morning sickness pill in ‘50s cause severe birth defects.

5. Allergens
Over-activate the immune system, causing an immune response when it is not necessary.
e.g. asthma is thought to be a response to synthetic chemicals that are more prevalent in our environment.

6. Neurotoxins
Chemical
Attacks the nervous system - coordinates action and transports signals
e.g. heavy metals; lead, mercury (fish), cadmium, some pesticides, chemical weapons, etc.

7. Endocrine Disruptors
Chemicals that interfere with the endocrine system
Hormone system: messenger molecules that serve vital functions;
stimulate growth, development and sexual maturity,
regulate brain function, appetite, sex drive, other physiology and behavior