Types of Toxicants

Classification based on particular effects on health

Carcinogens

• Chemicals or types of radiation• Cause cancer - uncontrolled cell growth– Greatest # of cancer cases is thought be related to

carcinogens in cigarette smoke

Mutagens

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

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.

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.

Neurotoxins

• Chemical• Attacks the nervous system - coordinates

action and transports signals– e.g. heavy metals; lead, mercury (fish), cadmium,

some pesticides, chemical weapons, etc.

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