7 December 2019 | New Scientist | 41want to scare people; some of the data is
comforting,” says Vrisekoop. “But some
of it is worrying too.”
Vethaak accepts the World Health
Organization’s line that if there was a serious
risk from microplastics we would be seeing it
already. But he nonetheless suspects that they
are contributing to the epidemic of chronic
inflammation that has been linked to diseases
such as neuro-degeneration, cardiovascular
disease, diabetes and cancer. “We are exposed
maybe only to low concentrations, and maybe
these particles are not so toxic themselves, but
it is lifetime exposure and there is potential
that they may accumulate in organs. And we
know that they have the potential to cause
inflammation,” he says.Bad to worse
What, then, can be done? Vrisekoop advises
avoiding plastic packaging and urges food
manufacturers to do their bit by offering
plastic-free alternatives.
We could also do more to eliminate some of
the sources of microplastic pollution, such as
banning single-use items, says Vethaak. The
personal care industry has already committed
to eliminating microbeads from toiletries and
cosmetics next year, which will choke off
around 10 per cent of the microplastics
entering the sea from rivers.
But these are a microdrop in the ocean.
Given how much plastic rubbish is already
out there, microplastic pollution will continue
to rise for the foreseeable future as this waste
breaks down. “Even if we stop plastic pollution
right now, there will still be increasing levels
for decades,” says Vethaak. And existing
microplastics won’t vanish, but keep on getting
smaller – and potentially more dangerous – as
they circulate from water to air to soils and
ultimately into our bodies.
One thing everybody agrees on is that there
are more questions than answers. Vethaak
says he sees progress, but there is a long way
to go. “I think it will take many years, maybe
even a couple of decades, of research before we
come up with some hard evidence or a better
understanding of what’s happening,” he says.
“Is there a risk? I don’t know. But I think we
should find out ASAP. I think there is no time
to waste.” ❚“There’s really a lot of work to be done,” she says.
In another early finding, toxicologists at
Utrecht University discovered that cultured
human placenta cells can absorb polystyrene
beads that are 200 nanometres across. A third
study found that lung tissue incubated with
microplastics died.
These are preliminary results and hardly
add up to a comprehensive case against
microplastics. For one thing, the full relevance
to human health is still unclear. But many
researchers in the field say that there are
already good reasons to believe that chronic
exposure is detrimental to our health. “I don’tGraham Lawton is a staff
writer at New Scientist.
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@GrahamLawtonGETT
Y^ IMAGESmice, microplastics can be detected in the liver,
kidney and gut, which means they are likely to
come into contact with the immune system.
To find out what might happen in humans,
she added polystyrene microbeads to dishes
containing immune cells called neutrophils,
which engulf and kill bacteria and other
invaders. Some of the microplastics were pure,
uncontaminated plastic; the neutrophils just
ignored them. But spheres coated with blood
plasma – to mimic how they are likely to be
encountered by the immune system after
circulating in the bloodstream – triggered
the neutrophils to attack and engulf them.
The neutrophils then died. “We find quite
extreme effects,” says Vrisekoop.
The implications for human health are
worrying, she says, though there are still many
unknowns, such as whether the microplastics
trigger repeated neutrophil attacks in a chain-
reaction immune response. “That really
requires further research,” she says.
Vrisekoop now plans to investigate
whether microplastics ingested by mice
activate their immune system. She and
collaborators at the Amsterdam University
Medical Center are also developing an assay to
measure microplastic loads in human tissue.
800
Number of microplastic particles
in a portion of musselsWear and tear of tyres
on roads is a leading
source of microplastics