In the Federal Court this week,Justice Michael Lee confirmed the settlement terms leave the door open to a personal injury action.

Professor Osborne based his findings on an examination of the scientific literature,30 years experience and expert reports written on behalf of each of the warring parties.

Those reports,by Professor Phillipe Grandjean and Professor Tony Fletcher,were in"broad agreement"there was enough evidence to say PFAS potentially caused health effects.

Professor Osborne noted a different approach was taken by the Australian government’s expert health panel,appointed to investigate the effects of PFAS in 2018.

It found"no evidence"that PFAS caused any"important health effects",on the same day as a government announcement there would be no buy-outs for people stranded on toxic properties.

As recently as last week the federal government told a parliamentary inquiry its advice was"PFAS probably has minimal impact on human health".

Professor Osborne noted there were"mixed"ideas about the effects of PFAS in the scientific community,and reports were also written with"different audiences in mind".

However,he argued that using a higher bar sometimes posed a risk to communities exposed to a chemical while they were waiting for scientists to collect enough evidence to prove it was hazardous.

"This can be decadal or even generational in length (ie the continuing lowering in acceptable levels of air pollution since the 1950s),"Professor Osborne noted.

He also stressed that in science it was difficult to reach the point where a chemical could definitively be said to cause a certain health problem.

Instead,the risk was usually assessed on a"sliding scale of this probability from likely to unlikely"based on an evolving body of scientific evidence.

Most of the research on PFAS began after the year 2000 and for the first decade was nearly exclusively industry funded.

Internal 3M documents that emerged in an overseas lawsuit saw the company accused of funding studies so it could"command the science" on PFAS and attempting to suppress damaging academic research.

In 2016 aNewcastle Herald investigationuncovered 50 cancer cases along a NSW road heavily polluted with PFAS.

Professor Osborne said it was a"rapidly moving field"with a"high volume of studies"under way.

"No doubt new evidence will be released in the forthcoming years that will alter our thinking around PFAS,"he said."Great changes are expected in the near future."