These adverse effects may range from slight symptoms such as headaches to severe symptoms like coma and convulsions or death. Most toxic effects are reversible and do not cause permanent damage if prompt medical treatment is sought. Poisons work by altering normal body functions, consequently toxicity can occur in as many ways as there are body functions. All new pesticides are tested to establish the type of toxicity and the dose necessary to produce a measurable toxic reaction. In order to compare the results of toxicity tests done in different laboratories, there are strict testing procedures.
Toxicity testing is expensive and extensive, involving many phases.
Humans, obviously, cannot be used as test animals so toxicity testing is done with animals. Since different species of animals respond differently to chemicals, a new chemical is generally tested in mice, rats, rabbits and dogs. The results of toxicity tests in these animals are used to predict the safety of the new chemical to humans. Toxicity tests are based on two premises. The first premise is that information about toxicity in animals can be used to predict toxicity in humans.