Bruce Ames was a scientist best known to the world as the inventor of the “Ames Test,” a relatively inexpensive and quick way of determining whether a chemical can cause cancer in mice and rats.
His test was used (and still is used to some degree) to take chemicals off the market and inform various product regulations.
However, as time went on, Ames and his colleagues discovered that when mice were exposed to very high doses (thousands of times what any human would be exposed to) of any chemical, the result was cancer one of every two times. And this happened as often with natural chemicals as it did with manmade chemicals.
Finally, Ames came to realize that it was probably the high dosage bombardment, not the chemicals themselves, that was causing cancer.
The lesson. It’s not true that everything causes cancer. But it is true that every other thing causes cancer, if the dosage is high enough.