As pressure mounts for a global ban on the use of microbeads in cosmetic products, researchers have for the first time shown they directly contaminate fish with toxic chemicals.
Plastic microbeads that have been washed into rivers, lakes and oceans are increasingly recognised as a major environmental problem, with an estimated 8 trillion beads washing into aquatic habitats each day in the United States alone.
The tiny polyethylene particles – used in products such as skin exfoliators and toothpastes – act like a magnet for pollution in water and they pose a particular risk to fish, who mistake them for food.
Now a team of researchers from RMIT and Hainan University in China has shown that up to 12.5 per cent of the chemical pollutants on the microbeads can pass into the fish that eat them.
Lead investigator Dr Bradley Clarke, from the Centre for Environmental Sustainability and Remediation, said the study was the first conclusive evidence that microbeads were capable of leaching toxic chemical pollutants into fish that eat them.
“We know that fish are eating microbeads but until now we haven’t had proof that they play a direct role in moving pollution through the food chain,” Clarke said.
“All plastic attracts and concentrates toxic chemicals when in water, but this problem is compounded with microbeads because of their size and surface area.
“Our research shows for the first time that persistent organic pollutants accumulate in the tissue of fish that eat microbeads.
“We know generally that if someone eats a fish, they risk eating any pollution that may in the fish.
“Our next step is to determine the implications of our findings on microbeads for public health – working out the significance of this exposure pathway and precisely measuring how much pollution could be entering this human food chain.”
The research focused on polybrominated diphenyl ethers (PBDEs) – pollutants known to biomagnify up the food chain in marine animals.
Eating fish and shellfish is linked to elevated levels of PBDEs in humans.
In the controlled laboratory study, Murray River rainbow fish were fed microbeads sourced from a commercial facial cleanser, which were spiked with environmentally-relevant concentrations of PBDEs.
The exposed fish had significantly higher PBDE concentrations than the control group after just 21 days - 5.03 nanograms of PBDE in every gram of fish tissue compared to 1.47 for the control group - with continued exposure resulting in increased accumulation of the pollutants.
Overall, the study showed that up to 12.5 per cent of PBDEs on the microbeads leached into the tissue of the fish.
The US government has passed laws to ban the use of microbeads from mid-2017, while in Australia the Federal Government is working with companies towards a voluntary phase-out by July 2018.
The research has been published in the journal Environmental Science & Technology.
Story: Gosia Kaszubska
Video: Peter Clarke