The greater the exposure above the ADI, the greater the potential risk. We want to set a limit on mercury in drinking water. The goal is to ensure the RfD is not exceeded. Often mercury also is taken in from food. Carcinogenic risks Potency of a carcinogen is an estimate of the upper limit on lifetime cancer risk associated with one unit of the average daily lifetime dose.
Steeper slopes are more dangerous.
Under this model of cancer risk, the upper limit on lifetime risk is estimated by multiplying the cancer potency by the number of dose units individuals are exposed to each day. If people drink 2 liters a day, 0.1 mg of chloroform are consumed. This means 8 out of 1,000,000 people will develop cancer from drinking chloroform in the water during a 70 year lifespan.