I was using the chemical process of chemotherapy as an example of a disproportionate effect of a process. The specific process chosen by me was immaterial to the argument, except that it was a convenient example of the effect I wished to describe. My use of the word substance was perhaps imprecise, as it is usually reserved for items with mass, which ionizing radiation does not have. But it was, again, immaterial to the idea of a disproportionate effect, which is what I was actually conveying. And I am choosing to label as pedantic the attempt to disarm my point by discussing the word chosen as opposed to the point being made.
