Assessing the occurrence and human health risk of per- and polyfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFAS) are a large group of human-made chemicals used in many industrial processes and consumer products. Because PFAS are widely used, people can be exposed to them through several sources, including drinking-water, food, consumer products, and some workplaces.

PFAS are often called “forever chemicals” because they break down very slowly and can remain in the environment for a long time. Growing evidence of their widespread presence and potential effects on human health has led the World Health Organization (WHO) to review the science on PFAS.

As a first step (Phase 1), WHO carried out a broad review of the available evidence to identify the PFAS most relevant to human exposure and the health effects that may be of greatest concern. This landscape review identified 18 priority PFAS and 6 priority health effect categories for further study.

WHO is now conducting more detailed reviews of the scientific evidence on these priority PFAS and health effects (Phase 2). The findings will help inform the development of health-based guidance values for PFAS in food and drinking-water through the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and WHO's guideline-development process.

To support this work, WHO has also commissioned the development of tools and methods for collecting and evaluating scientific evidence, as well as approaches for assessing PFAS as a mixture. These resources are being updated to reflect the 18 priority PFAS, the 6 priority health effect categories, and advances in PFAS risk assessment.