So-called 'forever chemicals' explained

* PFAS is the short-hand name for a family of manufactured chemicals used in industry and consumer products since the 1940s

* There are thousands of types of per- and poly-fluoroalkyl substances (PFAS) and they are valued for their heat, water and stain repelling properties

* They're present in a vast range of industrial and consumer products including food packaging and non-stick cookware to make-up, shampoo, paints, sealers and stain-resistant carpets and fabrics

WHY ARE REGULATORS CONCERNED?

* PFAS are sometimes referred to as forever chemicals because they are long-lived, and don't easily break down in the environment

* They are often toxic and can accumulate in plants, including agricultural crops, and in the bodies of animals including humans

* Experts say they are now ubiquitous, meaning they are found everywhere on earth

* PFAS have been found in Antarctica and in Arctic Sea ice, where there is no obvious source of contamination

HOW DOES IT AFFECT HUMANS?

* Scientists suspect PFAS may pose broad health risks including cancer but research is inconclusive so far

* The US Environmental Protection Agency cites peer-reviewed scientific studies that have shown exposure to certain levels of PFAS may lead to increased risk of some cancers, including prostate, kidney, and testicular cancers

* It points to other studies showing there may be increased risk of fertility issues, developmental effects in children, immune system impacts, hormonal interference and increased cholesterol levels and/or obesity risks

* The EU's responsible agency says PFAS can lead to problems such as liver damage, thyroid disease, obesity, fertility issues and cancer

* It says of the relatively few well-studied PFAS most are considered moderately to highly toxic

* Australia's health panel for PFAS says there are fairly consistent reports of an association with several health effects while noting they are generally within normal ranges for the whole population.

* It says there's no existing evidence suggesting an increase in overall cancer risk

* Australians generally have at least three types of PFAS in their bodies

* PFOS, PFOA and PFHxS are readily absorbed through the gut, and once present in a person's body it takes two to nine years, depending on the study, before levels go down by half, even if no more is taken in

* Australia decided about 14 years ago to phase out the most concerning PFAS and recommends ongoing exposure should be minimised

WHAT ARE THE ENVIRONMENTAL CONCERNS?

* PFAS have been shown to be toxic to some animals and can bioaccumulate and biomagnify in some wildlife, meaning animals higher up the food chain may accumulate high concentrations in their bodies

* The toxicity, mobility, persistence and bioaccumulation potential of PFAS means they have the potential to cause serious environmental and human harms depending on exposure levels

* PFOS and PFOA are highly persistent and can travel long distances in water and in the air

Australian Associated Press