The toxicity of most chemicals requires metabolism to toxic forms, but metabolism also produces less toxic forms of chemicals. Large differences in chemical metabolism are often observed between animal species and humans. Since the metabolism of potential cancer-causing chemicals cannot usually be studied directly in people, laboratory methods that can accurately predict chemical metabolism in humans are needed. CIIT researchers have shown that studies using isolated rat liver cells accurately describe the metabolism and toxicity of several toxic chemicals in whole animals. These results suggest that isolated human liver cells can be used to predict human metabolism of toxic chemicals.
Furan produces liver cancer in rats and mice and therefore has been studied in detail.
However, there is uncertainty in how to use these results to estimate human cancer risks. Furan is used as a solvent and is present in many foods such as coffee and canned meats. Trace amounts of furan have been found as contaminants in the atmosphere of the Mir space station. High concentrations of furan are thought to produce cancer in rodents through sustained liver toxicity and increased cell division. Knowledge of furan metabolism in humans compared with rats and mice is needed to estimate human cancer risks from furan exposure.