ABSTRACT
Repeated-dose toxicity studies are conducted to screen for potential adverse effects of a chemical using laboratory animals as surrogates for a target species, most often the human. Repeated-dose studies may be of varying duration, generally 1 to 4 weeks for short-term studies, 3 months for
subchronic
studies, and 6 to 12 months for
chronic
studies. Many variables associated with the health of the test species are monitored in short-term, subchronic, and chronic toxicity studies, resulting in the ability to detect a variety of adverse effects. At some time during their careers, most toxicologists are involved in the design, performance, or review of data from these toxicology studies. This results from the central role played by these studies in the safety assessment of pharmaceuticals, pesticides, food additives, and other chemicals. It has been suggested that subchronic data alone
may be sufficient to predict the hazard of long-term, low-dose exposure to a compound [51]. Although this may be true for compounds where adequate structure-activity relationships exist and with no indication of genetic toxicity, it generally is not true when compounds have completely unknown toxicity or when structure-activity relationships predict a potential adverse effect. For certain chemicals or mixtures, results from a short-term or a subchronic toxicity study may represent the most sophisticated toxicology data available. With many chemicals, a subchronic study is critical to the design of longer term hazard assessment studies.
