Scientists are concerned about the potential human health hazards posed by microbeads in the environment
Scientists are becoming increasingly concerned about the potential human health hazards posed by microbeads in the environment
Australian research has provided stark evidence of how tiny plastic particles flushed into waste water soak up toxic compounds and carry them into the food chain.
In laboratory tests that mimicked the chain of events occurring in the wild, plastic microbeads taken from a facial cleansing product were dosed with a common pollutant by environmental scientist Bradley Clarke of Melbourne’s RMIT University.
The research, conducted on Murray River rainbow fish, for the first time measured the toxins accumulated in the tissue of fish that had been fed “environmentally relevant” amounts of the chemical-spiked polyethylene beads.
“Our evidence is very strong because we calculated how much we exposed the fish to,” Dr Clarke said of the research, which is documented in the current issue of Environmental Science and Technology.
“People were predicting this would happen, but there was very little evidence to that point to demonstrate it.”
Dr Clarke’s team found 12.5% of the chemicals – in this case, polybrominated diphenyl ethers (PBDEs), used as flame retardants in manufactured products – remained in the flesh of fish that had eaten the beads.
A specialist in persistent organic pollutants (POPs), Dr Clarke chose PDBEs for the experiment because such compounds can biomagnify in marine life, and fish and shellfish consumption has been linked to PDBEs in humans.
The POP classification means a chemical is not only toxic but is persistent in the environment, bio-accumulates in humans and animals, and is capable of long-range movement.
“So it can be found in places you would not expect – in the Arctic, for instance,” Dr Clarke said. PDBEs and fire-fighting foams are second-generation POPs; the first generation includes the insecticides, dieldrin and DDT, now banned in most countries.
Until recently, campaigns against plastic pollution have focused on the blight of plastic bags and bottles on oceans and waterways, and the consequences of plastic garbage that entangle and become swallowed by turtles, sea birds and other marine animals.
But scientists are increasingly concerned about the hazards of barely visible micro plastics and the potential impact on humans.
“I think the problem could be far more extensive than has been characterised at this point,” Dr Clarke told The Medical Republic.
“There have been reports of plastics in filter feeders, plankton, oysters. When you start unpacking it beyond fish, (the problem) could be much more impactful than we are contemplating.”
Despite bans recently imposed in some western countries, billions of microbeads, used in household toiletries including exfoliants, shampoo and toothpaste to control texture and viscosity, are flushed away every day.
Thousands of beads are released into waste water with each product use. But the global scale of the impact can hardly be estimated, because measuring techniques have not kept pace with changes in products being released into the environment.
Whereas most studies had measured particles down to a size of 333 micrometres, a facial scrub could contain plastic granules of between one and 1000 micrometres (one millimetre), indicating one-third would escape notice, Dr Clarke said.
And where research had estimated that 25% of fish for human consumption had plastic in their guts, that work had relied on visual inspection.
Tiny particles that are readily ingested by marine life, and which are possibly more pervasive in the food chain, were not in the frame.
However, the ability of plastics to act as vehicles for toxins and pathogens drawn from the aquatic environment is well known.
International research has shown plastics can attract and store POP compounds at concentrations a million times greater than in the surrounding sea water.
“They love being on the polyethylene, they don’t like being in the water,” Dr Clarke said.
“The sea surface boundary layer is where the pollutants sit, and also where the plastics float. So you have this mechanism where the two meet, and the POP absorbs into the plastic by the power of up to a million.”
By the same power of attraction, the fat-soluble compounds accumulate in human and animal tissue, including in breast milk.
Dr Clarke said it was “difficult to distil the health consequences” of his findings, but the POP compounds had been linked with reproductive health problems and immunological and neurological damage.
“The other thing to remember is that these POPs are present in the food chain anyway.
But what we don’t need to be doing as a society is adding more pollution into the environment that we know will facilitate transfer of POPs.”
While putting microbeads in cosmetics and personal care products looks like avid disregard for the environment, other microplastic litter includes fragments from larger plastic refuse and escaped pellets known as “nurdles”, which are used in production of plastics.
A new focus of alarm, however, is acrylic and polyester microfibres from synthetic textiles which have become ubiquitous in marine and terrestrial debris and are showing up in seafood that people eat, according to marine ecologist Dr Mark Browne.
“For the granules, medical research shows the smaller the particles, the greater the rate of transfer into and out of organisms,” the University of NSW researcher said.
“But for fibres it shows something really quite interesting – a sort of not-so-sweet spot for the length of fibres that can actually cause a lot of irritation. They can get stuck in different organs, the lungs or the gut, and start causing problems.”
Where inflammation and fibrosis could occur, the next logical link in terms of pathogenesis could be tumour formation, “but that’s really where we need more research”, Dr Browne said.
When Dr Browne began his research into microplastics in 2004, most literature on the subject came from medical science. Now, he says, medicine could offer insights and a regulation model to solve the plastic debris problem.
“In medicine, before a product can go on the market, say a hernia mesh or an artificial joint, it has to be demonstrated that it emits very small quantities of debris and that it’s less toxic (than an alternative). Unfortunately, non-medical products don’t have that level of oversight, and that has created some of the problems we have now,” he said.
A regulatory approach applying the medical principles of advance testing and biocompatibility would avoid repeating errors in which materials have been banned, only to be replaced by ones equally as bad.
“Waste management can’t really cope,” he said. “We have allowed companies to produce products with no stewardship over what happens when the products end up as waste.
“It’s a policy issue. In medicine, it’s sorted. In non-medical products we are starting to realise if you don’t regulate them, you have problems.”
Handed down in April, a Senate report on the threat of marine plastic pollution in Australia urged the federal government to devote more support to research on marine plastics, and adopt an immediate ban on the importation and production of personal care products containing plastic microbeads.
The government agreed in February to a “voluntary” phase-out of microbeads by 2018 at the latest, following the lead of the United States and some European countries. The phase-out is expected to take some years, since manufacturers want time to make the transition to replacement products.
Greens Senator Peter Whish-Wilson, who chaired the Senate inquiry, told The Medical Republic he would renew the demand for stronger action in the current session of parliament.
“From the environmental point of view, an immediate ban is the way to go,” he said, pointing out that voluntary phase-out agreements had not been successful in areas such as recycling of tyres and e-waste.
“This stuff is going into the ocean every day and making the pollution issue worse, and I don’t understand why we are delaying. This is one of the biggest pollution issues in the world, and I reckon it’s the one we hear least about.”
The Tasmanian senator said the government could stop the dissemination of microbeads using the powers of the trade and industry ministers, but addressing synthetic microfibres would be more difficult and probably require fitting filtration devices to washing machines.
Curiously, there appears to be little discussion so far about the principle of polluter-pays and microplastics. But that could be a failure of the imagination.
Dr Browne recalled holding talks with officials from Nike, the sports apparel manufacturer, about the issue of clothing shedding synthetic fibres.
“The first thing they asked me was, is this the new asbestos?’ he said.
“When you look at an issue like asbestos – caused by a fibre-sized particle, and some kinds of asbestos were once used in clothing – this is the example. If you have poor policies in place, you can have a human health issue.”
The US government has prohibited the manufacture of rinse-off cosmetics containing microbeads from July 2017, and sale from July 2018, with deadlines for non-prescription drugs to follow a year later.
Major Australian retailers, including Coles and Woolworths, and toiletry makers have pledged to step away from microbeads. But a formal commitment on the voluntary phase-out in cosmetics, household cleaning and therapeutic products was still being formalised, an Australian Food and Grocery Council spokesman said.
The accord envisaged two- and three-year phase-out dates for existing products, partly to reflect the need for regulatory procedures such as Therapeutic Goods Administration approvals for replacement products.
Beat the Microbead – a website maintained by NGOs – carries a list of countries, manufacturers and products containing microbeads and indicates the progress towards wiping out industrial use of the beads. It can be found at www.beatthemicrobead.org.
