Microplastics from
the washing machine
MARTINA
PETER
Even
before the UN Ocean Conference in early June, we already knew about the
disastrous ways in which plastic affects the world's oceans.
Billions
of pieces of plastic are floating in the oceans. Their effects are also
sufficiently well-known: marine animals swallow them or get tangled up in them,
which causes them to die in agony.
On
the other hand, we know less about the consequences of the smallest pieces of
plastic, known as microplastics. Empa researchers have now started to
investigate how microplastics are generated and where they actually come from.
The
presence of microplastics in our wastewater can be attributed primarily to two
factors.
Firstly,
many cosmetic products, such as toothpaste, creams, shower gels, and peelings,
contain tiny pieces of plastic in order to achieve a mechanical cleaning
effect.
Secondly,
microplastics are washed out in the process of washing polymer textile
clothing, and thus they enter our environment via wastewater.
Many researchers who have recently studied nanoparticles are now also investigating microplastics. They include Bernd Nowack, Edgar Hernandez, and Denise Mitrano (who is now working at the water research institute Eawag) from Empa's "Technology and Society" department.
On
the basis of their nanoparticle research, these three researchers recently
published a first quantitative investigation of the release of microfibers from
polyester textiles during washing, in the specialist journal
"Environmental Science and Technology".
In
this study, the Empa team primarily investigated the ways in which washing
agents, water temperature, and the number and length of wash cycles affect the
release of microfibers.
A hypothesis that could not
be confirmed
To
date, the study is the most meticulous and systematic investigation of the
release of microfibers from textiles that has ever been carried out.
This
applies both to the quantity of parameters investigated and to the
characterization of the released fibers in terms of number and length.
Nowak
and his colleagues found out that the quantity of fibers released by five
different washing programs was always more or less constant, while washing
agents and detergents increased the quantity of microfibers released compared
with "normal" water.
However,
washing temperature had no effect on the number of microfibers that Nowack's
team subsequently found in wastewater.
Remarkably,
the same was true of the duration of the wash cycles. "And for us, that
was really quite astonishing," says Bernd Nowack.
He
had assumed that they would confirm the well-established hypothesis that the
longer a wash cycle lasts, the more microfibers it will release. "At
first, it looked as though microfibers were generated during washing,"
says Nowack.
However,
if this were the case, longer wash cycles should release more fibers. But this
is not the case. The Empa researcher makes a frank admission:
"Unfortunately, this means that we are not yet able to explain how the
released fibers are generated."
A good basis for follow-up
investigations
To
ensure that this does not remain the case, a follow-up study is already
planned. In cooperation with Manfred Heuberger of Empa's "Advanced
Fibers" lab, a PhD thesis on the generation of microfibers during washing
will soon be underway.
This
study will then systematically analyze different types of materials in order to
shed light on the generation of microfibers in the washing machine.
