Scientists at Waipapa Taumata Rau, University of Auckland
are investigating just how much plastic New Zealanders are
inhaling, especially indoors where most people spend most of
their time.
Dr Joel Rindelaub and Dr Gordon Miskelly,
of the School of Chemistry, tested the air in two chemistry
labs for microplastics small enough to be inhaled, particles
similar in size to fine silt or sand or pollen.
The
average concentration of plastic was 830 nanograms per cubic
metre of air, more than ten times higher than a reading at
an outdoor site elsewhere.
A nanogram is one billionth
of a gram.
“Most of us spend most of our time
indoors, that’s how we live,” says Rindelaub. “And
since indoor levels of microplastics are generally higher
than outdoors, we need to know much, much more about our
exposures and the potential health
risks.”
Importantly, chemical additives,
which may pose greater health risks than the plastics
themselves, were also detected. Phthalates, endocrine
disrupting chemicals used to make plastics flexible, were
present at an average level of 334 nanograms per cubic
metre.
Globally, scientists have yet to
standardise methods for measuring microplastics, with many
past studies undercounting by failing to pick up the very
smallest particles, which are also the most
numerous.
In addition to detection in the human liver,
blood, faeces, and placenta, microplastics can lodge in the
lungs and US scientists have analysed brains containing the
equivalent of five plastic bottle caps.
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Rindelaub
hopes the fast and simple chemical technique trialled in his
research using pyrolysis gas chromatography mass
spectrometry becomes more common
internationally.
Seven types of plastic were detected
in the laboratory air, likely coming from sources such as
building materials, lab equipment and packaging, according
to the study
in the Journal of Exposure Science & Environmental
Epidemiology.
The highest concentrations were of
polycarbonate, polyvinylchloride, and polyethylene.
A
separate study
by Rindelaub and his colleagues, published in the journal
Environmental Pollution, tested coastal air at a site
about 50 km west of Invercargill. Here, the average
concentration of inhalable microplastics was 65 nanograms
per cubic metre of air – comparable to an average of
hugely variable urban readings around the world.
Based
on wind direction, the Southern Ocean seemed to be the key
source of the plastic, acting as a reservoir of particles,
likely propelled into the air via breaking
waves.
Rindelaub and his colleagues found about 4,625
microplastics per square metre of surface area per day in
the Southland study, similar to about 4,885 in a previous
study in Auckland.
The Auckland amount was the
equivalent of 3 million plastic bottles falling from the sky
a year.
“Detecting similar amounts in a remote area
and a big city indicates there is a lot of plastic coming to
us from the ocean,” Rindelaub says.
What can
you do?
Avoid using plastic when possible;
don’t eat food from heated plastic containers since they
leach chemical additives; ventilate your home and if
possible, get a home air purifier, says
Rindelaub.