In a small metal chamber, in a metal room, in a tightly sealed Brisbane lab is one of the rarest things on earth - a space almost entirely free of plastic.

Scientists have gone to extraordinary lengths to create it in a bid to answer some burning questions.

Among them is whether the pollutant that's contaminated every part of the planet has also infiltrated the innermost reaches of the human body, including the brain.

And if it has, what damage might it be doing?

They are big questions that will take time to answer and one of the first steps is to understand how humans might be internally exposed to minuscule particles of plastic.

That means going looking for them, in urine, blood and brain tissue.

But when plastic contamination is literally everywhere how can scientists be confident that any particles they might find are evidence that plastic is crossing membranes in the human body?

How can they be assured samples haven't been tainted by plastic and plastic-related chemicals that are constantly swirling around, in the air, in water, in clothes, everyday items and building products?

That's where the purpose-built, contamination-controlled, air-lock protected lab comes in.

The facility, which opened in 2022, is made almost entirely from stainless steel. Plastic is excluded to the greatest extent possible.

The air is filtered many times a minute to ensure any circulating particles are captured and immobilised. And there's constant positive pressure, ensuring air flow is always outwards, never in.

Researchers must transition an ante room and air lock and don pure cotton lab coats to limit the risk of them shedding plastic, which is in most textiles.

When they are finally inside the clean room and it's time to open brain and other samples, that's done inside a smaller metal chamber, a kind of clean room within a clean room.

It's an extraordinary process but entirely necessary, says Kevin Thomas, the director of the University of Queensland's Alliance for Environmental Health Sciences.

"You have to get that background signal down to as low as possible, preferably below what you can detect, which is what we can do for nano plastics in there," he says.

Most people have heard of micro plastics - small fragments of plastic that are less than 5mm in length.

But they're enormous compared to the nano plastics Prof Thomas is looking for, the kind that might be capable of crossing the blood-brain barrier that protects the organ from circulating toxins or pathogens.

"To give you and idea of how small we're going, we're looking for things that are 1000 times smaller than the width of a human hair - and below that.

"Our first goal is to be able to reliably measure them so we can actually say definitively whether they have crossed membranes into the body."

Answering that crucial question will help determine what happens next.

"It's really the first stage in going down the route of saying 'well if a particle does cross into the brain, what's the impact of that particle's presence?'.

"The body may be able to deal with it, or there may be mechanisms that occur that may start some sort of adverse outcome."

The lab is the beating heart of the Minderoo Centre - a partnership between the university and mining billionaire Andrew Forrest's philanthropic Minderoo Foundation, which funded the lab.

Sarah Dunlop, the foundation's head of plastics and human health, says the partnership is focused on two areas of research - detecting plastic particles themselves and studying chemical additives that leach out of plastic.

"We are fighting the invisible. You can see the plastic floating in the ocean, but you can't see the plastic pollution in us," the professor says.

"If we prove that nano plastics are in our brain or blood, that in itself is an invasion; a toxic trespass.

"Detecting plastics and having faith in the results is a very powerful statement to say to the world this plastic pollution has to stop. But it's more than that. We have to be totally disruptive and redesign plastic, so it doesn't fragment into micro and nano plastics and doesn't contain toxic chemicals.

"We hope that the scientific findings will shape government policy and health advice on plastic exposure and the chemicals."