Most people avoid spilling their guts in public. But Liz Bonnin didn’t blanch when she was invited to test for everything that shouldn’t be in her body at the Plastic Health Summit in Amsterdam.

“I said I can’t wait, let’s do it,” laughs the Bafta-winning nature documentary presenter. “I was really excited. I knew what was going to show up but I want the world to know.”

Bonnin has had a front-row seat to the devastation wrought by plastics upon ecosystems. Last year she presented the ground-breaking BBC One documentary Drowning in Plastic, grimacing as she and her team ran cameras over baby seals strangled by plastic rope and a dead gull with a belly full of bottle tops. “And yet I still find myself standing in queues for coffee glaring at people who don’t have a reusable cup, thinking ‘what’s going on? Don’t you know that our oceans are dying?’” she says.

Last week’s summit represented the first time the world’s top scientists had gathered to explore research on the impact of plastic on human health. “Until now this hasn’t really been explored and that’s why there’s such a frustrating lack of funding into research,” Bonnin says. On stage, she received the results of a urine test revealing the levels of potentially harmful plastic-related chemicals in her body.

“The test results came back and I thought OK, I have these chemicals, and I can talk about them, that’s my job. But I did take a moment when it sunk in that the reality of the way we live had defused cancer-causing chemicals into my body. It was quite sobering and upsetting. Then I got on a train to Amsterdam and told everyone about it. I’m hoping it will help us to wake up.”

A growing body of evidence is pointing to the presence of microplastics and plastic additives in humans. Last year researchers at the Medical University of Vienna found 20 microplastic particles in every 10 grams of stool. “Plastic is a wonder material,” Bonnin insists, pointing to its use in MRI machines, life-saving equipment and aeronautics engineering. “But we have to look at how we dispose of it, and also how we make that material without these toxic chemicals. We have to be more mindful about how these plastic-based machines are made. But 40 per cent of all the plastic that’s made is this single-use food or drink packaging. That’s the bit that makes me want to tear my hair out.”

The Plastic Health Summit pushed a new line, however, arguing that “plastic is the new tobacco”. It’s the wake-up call Bonnin thinks we need. “Now that it’s human health we can show being impacted, are we going to sit up and pay attention?” she asks.

Bonnin’s test found pthalates and bisphenols — additives used in the production of plastic — in her body. They are said to leach in from food containers (like your microwave ready meal) and piping used in food manufacture. “The good news, I suppose, is they were found in lower concentrations than the average person in Amsterdam, and were lower than the average in an American study,” she says.

But “they’re harmful at a very low dose” and “interfere with your hormone function”. Such endocrine disruptors are linked to “hormone mediated disorders”, including “hormone mediated cancers, like breast cancer” while these chemicals “are also known to be toxic to reproduction”. They can affect fertility and cause conditions like endometriosis, when bits of the tissue that lines the uterus grow on other pelvic organs, causing pain, and “they can cause foetal abnormali-ties and birth defects.”

Although Bonnin notes the academic consensus expressed at the summit is still pending further study (a paper on microplastics​ in the blood is due in soon), she’s adamant that the damage plastics cause is unconscionable.

“What this test showed was that I’m being exposed to them and excreting them constantly — so as much as they cause harm for a short period of time before my body filters them out, the harm they’re causing is continuous.”

It’s not easy to put your body on the line. Bonnin is stark about the emotional toll her work has on her. She frequently finds herself enraged. “I am struggling,” she adds. She says she meditates a lot. “I haven’t tried screaming into a pillow yet, but who knows, I might?”

If all this sounds too gloomy, she’s “hopeful, albeit through gritted teeth” that humanity has the capacity to reverse its own impact. “There has to be room for hope but, my golly, we’re cutting it fine,” she says. “You know, I’m a big fan of [BBC presenter] Chris Packham, and he truly believes that the human race, at the moment, is like an unruly teenager, being a bit nonsensical and a bit silly. And eventually it’s going to just grow up and pull up its socks and get on with it. But let’s not rely on the younger generation and all that nonsense. I apologise to every one of these incredible young environmentalists for not taking better care of their future, right? It’s on us.”

She thinks Greta Thunberg is an inspiration. “I mean the girl’s extraordinary, when people criticise the UN talk all I saw was this young woman so fed up, so at the end of her tether with the same nonsense she was being spouted by those in power. I so felt for her.”

The September climate marches “give me hope that we’re making our voices heard in a way that’s unprecedented in our history”, she says.

Bonnin believes the emergence of politicians like Elizabeth Warren and Alessandra Ocasio-Cortez who refuse money from industry lobby groups is “essential”. She believes the need to pivot to a more conservationist economy is urgent. “Everything that comes out of David Attenborough’s mouth is the most glorious quote, but my favourite is ‘anybody who thinks you can have infinite growth on a planet with finite resources is either crazy or an economist.’ ”

She maintains, though, that there’s still grounds for producing nature documentaries that show the planet at its best, rather than the stark reality of man’s impact on ecosystems. “Because for me, I know that’s what got me to love my planet. And, when it comes to the good news and the bad news, I think there’s room for both.”