Using fish instead of rodents to test whether substances cause cancer would speed up the process while drastically reducing costs, a biologist says.
The notion that fish might be a useful alternative to rats or mice arose from studies showing that fish develop cancer when exposed to certain pollutants in the environment. In the Great Lakes, for example, researchers have found three "indicator species" that reliably develop tumors in the presence of certain contaminants. The species are the white sucker, the red horse sucker and the brown bullhead.
The cancer-testing process now costs up to $300,000 and takes up to two years, while the same testing could be done with fish for $10,000 in nine to 12 months, according to John Black, a biologist at Roswell Park Memorial Institute in Buffalo, N.Y., who spoke last week at a World Conference on Large Lakes in Michigan.
Because rodents are expensive to maintain in the large numbers needed for effective cancer testing, it has become impossible to test more than a minuscule percentage of the new chemicals that are emerging at the rate of 1,000 per day, Black said. The only existing alternative to testing with rodents is the Ames test, a simple and inexpensive procedure that reveals whether a chemical can cause mutations in bacteria. Substances that cause mutations are suspected of being able to cause cancer.