Consider the lifetime health risk of eating 100-g apples contaminated with 1 ppb (part per billion) heptachlor (a pesticide and probable human carcinogen). The potency factor for heptachlor has been estimated by EPA as 3.4 (mg/kg/day)−1.

a. On the basis of 70-kg adults who eat one apple per day for 70yr, roughly estimate the annual number of additional heptachlor related cancers one might expect in a population of 100,000.

b. Aside from the obvious consumption, lifetime, and body-weight assumptions, briefly discuss at least two other assumptions that underlie the estimate calculated in part a.