From The Oregonian:

_A rainbow trout can inspire and inform. It can lead a young fisherman to a life-long career studying human health. It can reveal the risks of carcinogens, and help develop treatments to prevent cancer. . . .

_George Bailey knows all this and has plenty of fish stories. As a professor, he spent three decades studying disease with trout in his aquatic laboratory at Oregon State University.

_It might seem odd that you can learn about people from trout, but in both animals, DBP [an environmental carcinogen] causes stomach and liver cancer by attacking and damaging DNA, tiny strings of molecules that contain cell-building information. People are good at repairing DNA, but trout have more difficulty. Like a canary in a coal mine, fish tend to get sick before people.

Rats and mice are canaries, too[, but trout] have an inherently lower cancer rate. Only one in a thousand trout would get stomach cancer, compared with the rat rate of one in 20. That’s why trout’s’ cancer risk to DBP can be measured at low levels.