The first rule of toxicology is that the dose itself is the poison. That is, every
substance is toxic if given at a high enough dose. Toxicity testing in animals (preferably
rodents) is required for investigational new drugs. The EPA conducts toxicity tests on
environmental chemicals through the National Institute of Environmental Health
(NIEHS) and the Environmental Toxicology Program (ETP). They give very large
doses of test chemicals to rodents to see if they might be harmful to the small portion of
humans who are highly susceptible to the test chemical. GLP was formulated by the US
Food and Drug Administration (FDA) to regulate non-clinical studies on the safety and
possible toxicity of a new compound. The European Organization for Cooperation and
Development (OECD) has its own GLP regulations that overlap with the FDA GLP.
Every GLP study must have a study director, who writes a study protocol and is
responsible for the design, conduct and reporting of the study. Many GLP studies also
have principal investigators (PIs). In contract labs that work for the NIEHS, there is a
single PI who has overall responsibility for the GLP studies. The PI has the authority to
approve all study protocols or any amendments.
Keywords: Toxicology, EPA, NIEHS, ETP, GLP, principal investigator.
