We ingest hundreds of pieces of plastic every day, study finds

There's a good chance you ingest hundreds of microplastic particles every day, a new study has found.

But scientists are split on whether that poses any threat to your health.

Microplastics - pieces smaller than 5mm in length - include fibres, microbeads, and pieces that have come off degrading larger items, such as plastic bags and drink bottles.

Researchers at the University of Victoria in Canada analysed 26 previous studies on microplastics to get an idea just how much ends up being consumed. They found the average person would consume between 74,000 and 120,000 a year - double if they drink bottled water regularly, rather than tap.

"There is no doubt that microplastics are already in our food chain, but more importantly everywhere in our ecosystems, oceans, lakes, rivers, streams, soil, air, everywhere," said Anas Ghadouani, environmental engineering professor at the University of Western Australia.

"The irony is that we have been saying that microplastics are everywhere in the environment - in the scientist mind, humans are part of the environment. So we meant humans as well. But it seems that there is some perceived separation between the environment and humans."

The researchers said the figures were likely to be underestimated, as they were only able to look at certain products - fish, shellfish, added sugars, salts, alcohol, tap or bottled water, and air - making up about 15 percent of the average person's caloric intake.

"Ingesting microplastics may be placing humans at risk of exposure to the various chemicals found within the plastic compounds," said  Paul Harvey, environmental scientist and environmental chemist at Macquarie University.

"This is particularly problematic and concerning for those who are more sensitive to environmental toxins including children and pregnant mothers."

While there is no doubt plastics in the environment are causing problems, whether they'll have a significant impact on human health remains to be seen, says  Lauren Roman, Postdoctoral researcher at Australia's Commonwealth Scientific and Industrial Research Organisation.

"There is currently no credible scientific evidence linking human dietary exposure to microplastics in their diet (shellfish, plastic bottles etc) to negative health effects."

She said deaths in the wild tend to come from macroplastics causing blockages in animals' stomachs, rather than microplastics.

"This doesn't mean that there are no negative health effects, it's possible there are and they just haven't been found, but imminent danger is very unlikely."

"Previous research estimated that humans get more exposure to microplastics from dust than food," added Oliver Jones, chemist at the University of Melbourne.

"That said, the data are certainly a wake-up call to the potential scale of the problem. Microplastics are an area where more science is welcome as we simply don't yet know enough about the issue to make robust conclusions about the possible risk."

The research was published in journal Environmental Science and Technology.