Final answer:
The FDA deems additives safe if lifetime use presents no more than a 1 in 300 in a million, or 0.03 percent, risk of cancer to human beings.
Step-by-step explanation:
The FDA deems additives safe if lifetime use presents no more than a 1 in 300 in a million, or 0.03 percent, risk of cancer to human beings. This is based on the linear hypothesis, which estimates the risks of low doses. It is important to note that even though small doses of radiation may cause long-term health problems such as cancer, the possible detrimental effects of much smaller doses attributable to artificial sources are more difficult to assess.