why does FDA tolerate more radiation than EPA?

Since the Environmental Protection Agency (EPA) began detecting radiation in rainwater and milk 

at levels above its maximum contaminant level, 

government officials have been downplaying the importance of EPA’s maximum contaminant level.

 - EPA does not allow drinking water to contain more than 3 picoCuries per liter of radioactive istotopes like iodine-131 and cesium-137.
   - FDA allows up to 4,700 picoCuries of iodine-131 in a liter of milk and up to 33,000 picoCuries of cesium-137.

- The EPA’s level is calculated so that in a population of one million people, the radiation will result in no more than one additional cancer fatality.
    - The FDA standard, on the other hand, accepts two extra cancer fatalities in a population of 10,000.