Perfluorinated compounds - EPA health advisory

 
What is a health advisory?
The EPA develops health advisories to provide information about substances that can cause human health effects and are known (or anticipated) to occur in drinking water. Advisories may include levels or limits for the substances, but typically the studies are still being completed when an advisory is created.
 
What is the EPA health advisory for perfluorinated compounds?
To provide Americans, including the most sensitive populations, with a margin of protection from exposure to specific perfluorinated compounds (PFOA and PFOS) in drinking water, EPA established health advisory levels for both PFOA and PFOS at 70 parts per trillion. When these two substances are found in drinking water, the combined concentrations should be compared with the health advisory level.

There is very limited scientific information on the health effects of other perfluorinated compounds, such as PFHpA, PFHxS, PFNA and PFBS. It is possible that the other perfluorinated compounds may have health effects similar to PFOA and PFOS. 

Health advisory level =
70 parts per trillion
or 0.07 parts per billion
 
How much is a part per billion or trillion?
One part per billion = 1 ug/L (microgram per liter)
This amount is equal to:
  • One drop of ink in a backyard swimming pool.
  • One grain of sand in a child's sandbox.
  • One second in 32 years.
One part per trillion = 1 ng/L (nanogram per liter)
This amount is equal to:
  • One drop of detergent in enough dishwater to fill a string of railroad tank cars ten miles long. 
  • One square inch in 250 square miles. 
  • One second in 32,000 years.