Microplastics
From Synthetic Clothing and Plastic in the Environment
Plastics
are very useful and popular materials, but they may be dangerous to animals and
humans while they are being used or when they are discarded. Chemical additives
leached from plastic containers, such as Bisphenol A, may disrupt our hormonal
systems, harm our reproductive systems and perhaps increase the risk of cancer.
Animals can become trapped in large pieces of plastic garbage, and both large
and small pieces may enter their bodies, physically or chemically injuring or
killing them. Plastics are widespread in our lives and in the environment, and
are sometimes present in unexpected places.
People who
refuse to buy plastic or who reuse plastic items if they do enter their home
should certainly be encouraged, but they may be shocked to learn that they are
probably still adding plastic material to the environment. Researchers have
discovered that every time clothing made from synthetic plastic fibers is
washed, tiny strands of the garments are removed in the washing machine and may
ultimately enter the ocean. Polyester, acrylic and nylon are examples of
plastics used to make clothing. One garment can release 1900 plastic
microfibers per wash. The fibers form an important part of the “microplastic”
present in the ocean. Plastic from other sources slowly degrades to contribute
to the microplastic material as well. In addition, very tiny nanoplastic
particles are present in many cosmetics and contribute to the plastic
collection in the oceans and its sediments.
The Problem
With Microplastics
What is Plastic?
Plastic is
a synthetic or semi-synthetic material which is molded and shaped when soft and
then solidified. Plastics are made of organic polymers. A polymer is a long
molecule made of repeating units, and the term “organic” means that the units
contain carbon. Plastics can be made from a wide range of chemicals, including
polystyrene, polyvinyl chloride (PVC), polyamide (nylon), polyethylene,
polypropylene and polycarbonate. One form of acrylic is poly(methyl
methacrylate), or PMMA. Acrylics and polyesters are families of plastics.
It’s often
thought that plastics don’t degrade, but they do in fact break down, although
generally very slowly. (There are some degradable plastics that break up faster
than normal plastics.) The long polymers that make up the structure of a
plastic gradually break up into shorter and shorter polymers. These degradation
products may still be dangerous to living things, however.
In
addition, additives used to make the plastic are released as the plastic
degrades. These additives include potentially harmful substances such as
bisphenol A (or BPA), which is used to make polycarbonate plastics and epoxy
resins, and phthalates, which are added to certain plastics to make them
pliable and are also present in some cosmetics. Both of these substances are
endocrine (hormone) disruptors, but whether or not low levels of the chemicals
harm adult humans is a controversial topic. However, many researchers agree
that the chemicals are dangerous for a fetus, young children and some animals.
How Do
Microplastics Differ From Plastics?
Plastics
are classified according to their size. Microplastics are plastic particles
less than 5 mm in size (or less than 1 mm in size in some classification
schemes). Nanoplastic particles are even smaller and are used in many personal
care products. These end up in the water when we wash our skin or brush our
teeth. (Many toothpastes contain plastics in the form of polyethylene glycol,
or PEG.) Plastics are so ubiquitous in our environment that it's hard for
someone to avoid absolutely all sources. A common method of classifying
plastics is shown in the table below.
Plastic Classification
|
Size
|
Megaplastics
|
> 100 mm
|
Macroplastics
|
100 mm to 5 mm
|
Microplastics
|
5 mm to 0.330 mm
|
Nanoplastics
|
< 0.330 mm
|
The Great
Pacific Garbage Patch
The Great
Pacific Garbage Patch is a huge, swirling mass of plastic and microplastic
material trapped in a gyre in the North Pacific Ocean and is known as the
largest landfill in the world. It's made of two areas called the Western
Garbage Patch and the Eastern Garbage Patch. The Eastern Garbage Patch is
larger, and its name is sometimes used as a synonym for "Great Pacific
Garbage Patch".
The
Eastern Garbage patch is very large, but its size is hard to measure and seems
to vary. It's been described as being equal to the size of Texas, equal to
twice the size of Texas or even equal to the size of Europe. The large pieces
of plastic debris in the region are very obvious, although they don't form a
continuous cover over the water as some people imagine. This is why the garbage
patch can't be seen in satellite photos. Most people are unaware that there is
a large quantity of hidden microplastic material in the area. The Great Pacific
Garbage Patch is shameful evidence of our love of plastic and our carelessness
about its fate and its effect on other creatures when it's no longer useful.
Potential
Dangers of Microplastics
The harm
caused by large pieces of plastic debris that enter the ocean is well known.
Animals may become entangled in the plastic or may mistake it for food. The
swallowed plastic may block the animals' intestines, starve them or suffocate
them. It may fill their stomachs and take the place of real food. The effects
of microplastics on living things are uncertain, but researchers are concerned
about their potential influence on the health of marine organisms and perhaps
even on us.
Scientists
know that microplastics are accumulating in oceans around the world and in
ocean sediments, that they take a long time to degrade completely and that they
are being ingested by marine animals at the bottom of the food chain. They have
also appeared in the bodies of fish. Researchers know that other pollutants
stick to the pieces of microplastic and are ingested along with the plastic
particles. These pollutants include dioxins, DDT and PCB molecules (polychlorinated
biphenyls). The plastic particles might be harmful, but investigators need to
demonstrate this in their research.
So much
microplastic material is accumulating in the ocean and it's made of such tiny
particles that if we do prove that the microplastic is hurting animals - or us
- it will be very hard to remove it. It's far easier to prevent the buildup of
microplastic (and nanoplastic) material than to remove it.
Studying
microplastic is a new endeavor and there's much that scientists don't yet know
about this form of plastic. Do the plastic particles hurt living things? Do the
pollutants that they carry harm animals? Do the plastic particles and the
pollutants become more concentrated as they move up the food chain? Do they
affect us when we eat marine animals? These are important questions which still
need to be answered.
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