Some agencies around the world have set drinking water limits or health advisories for some fluorochemicals, including interim levels for PFOA and PFOS.
People may have questions about what these limits mean, especially in areas where legacy PFOA/PFOS manufacturing may have taken place.
It’s important to know these advisories are often intentionally designed to provide a tremendously large margin of safety – so exceeding these advisory levels does not necessarily mean people’s health is at risk. However, people may not know whether this margin is based on an appropriate or practical level of caution for everyday decision-making.
For example, drivers are often taught to drive three car lengths behind the vehicle in front of them for safety. Someone could also recommend ten car lengths behind a vehicle, which may technically be safer. However, this does not make existing practice unsafe.
When considering drinking water limits, people should also understand the limitations of modern technologies to detect these materials at low levels. Some drinking water limits are so low that they cannot even be reliably measured by the most advanced technology available today. This can cause confusion and concern about the risk posed by very low detections of these substances in water.