In Module 7 we learned about risk characterization of exposures to carcinogens. The result or effect is often called the "endpoint." For the cancer endpoint we computed a slope factor (or had one computed for us). Then, for each receptor, we computed the risk of cancer via each exposure route, then summed the risks together, often in a summary table. For non-carcinogens a different process is used. This difference is based on an important assumption,
The "safe" dose of a non-carcinogen is called the reference dose, RfD. On the next page we will discuss characterization of exposures to non-carcinogens. FAQ: Can a chemical be both a carcinogen and a non-carcinogen? Answer: Yes, and many chemicals are both, some examples are lead, arsenic, many pesticides. If you are evaluating risks from such a chemical, you need to characterize both cancer and non-cancer risks separately. The risks cannot be added together.