"When I was a cancer patient I had another kind of epiphany about rivers, and that was when I studied in earnest the evidence of the rise of cancers among wildlife. And one of the things I think that people should know about to which not enough attention has been devoted is that not only have cancers been rising over the last half-century in the human population, but we have good evidence to say that in certain animal populations cancers are also rising. We in fact have a registry of tumors in lower animals. When I studied they were at the Smithsonian Institute; it's now at George Washington University. And that shows clearly that in populations, especially of aquatic animals, levels of-the prevalence of-tumors in certain animal populations are on the increase. And almost invariably when you see these tumors in animals they're located in populations with environmental contamination.
"So, for example, we know that there are rivers in which one side of the bank of the river has been contaminated with, for example, something like creosote, and a little fish called mummichogs that live there, these fish are real homebodies, they don't migrate up and down the river, they stay put. All the fish on that side of the river you'll see liver tumors in. You go across the bank to the other side of the river and you see another population of mummichogs and other kinds of minnows-less contamination, not so many tumors.
"So I think that animals who live in and by rivers can serve for us as a kind of early warning tool. Also with wildlife, you can't blame smoking, drinking, or stressful jobs on the rise in cancer, which so often we invoke those things to explain why we see more and more cancer in humans.
"So standing by my own beloved river, which is the Illinois River where I grew up, as a cancer patient (I was diagnosed with bladder cancer at the age of 20, bladder cancer is considered a kind of quintessential cancer) and looking into that river and realizing that there is plenty of evidence showing that fish who live in the Illinois have a high incidence of certain kinds of tumors.
"Realizing that I had something in common with the fish of this river we had both suffered from these tumors. It was a sort of spiritual moment, I think, for me, realizing that the suffering of cancer not only extends to human populations but to wildlife as well. Maybe the wildlife who live among us, especially in our rivers, have a message for we who live on the banks of those rivers."