What is the new proposed EPA limit for PFOS?

• A. 0.02 parts per trillion.
• B. 70 parts per trillion.
• C. 8,000 parts per trillion.
• D. 0 parts per trillion.

Answer: (A)

Regulators set drinking water limits for PFOS based on toxicology and exposure, aiming to minimize health risks from a chemical that is persistent and can accumulate in the body. The new proposed limit for PFOS is 0.02 parts per trillion, which is 0.02 ng per liter. This very strict number reflects an effort to further reduce exposure, given PFOS’s associations with immune, developmental, and hormonal effects, and its persistence in the environment. It is far more protective than the current 70 parts per trillion health advisory for PFOS and PFOA together, illustrating a shift toward a tougher standard. The other options don’t fit the latest proposal: zero would be impractical as a regulatory target, 8,000 ppt is not protective, and 70 ppt corresponds to older guidance rather than the new proposed limit.