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Why does a single plastic straw take 250 years to decompose?
Does it stay as a straw forever?
Plastic, as we all know, takes hundreds of years to decompose. Deep in the ocean, what we usually find would not be plastic bottles
and bags, instead we would find tiny bits and pieces of plastic. These are called microplastics.
Figure 2.1: Photograph by Rafflesian Brandon Shan from Class 4B, RI Inter-House Photography Competition (IHPC) 2020 [Theme: Plastic - Pollution or Solution?]
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Some microplastics
are known as primary microplastics,
which are plastics that are already smaller than 5mm when they are
manufactured, and some are known as secondary
microplastics, which are broken down from large plastic objects like plastic
bags into tiny pieces that are less than 5mm in size. Did you know? The dark blue spots in the toothpaste below are
examples of primary microplastics!
Figure 2.2 Artwork done by Rafflesian Y1 AEP Student Francis Loh
Microplastics are small pieces of plastic that are below 5mm in size. Every year, about 0.8 to 2.2 billion kilograms of microplastic are released into the oceans.
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Microplastics in
Cosmetics and Toiletries
Showering, brushing
your teeth, gelling your hair, applying makeup and putting on sunscreen: What
do these have in common? The products used in these activities may all contain
microplastics! Microplastics are used in cosmetics (makeup) and toiletries (bathroom
items) can exist in the form of microbeads,
like in the toothpaste above, as chemicals,
or as artificial silicone.
Figure 2.3: Primary Microplastics in Toothpastes
(Taken from video production by Y4 Chemistry Raffles Academy (RA))
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Activity Time: Plastic-free Luggage
COVID-19 may have stopped many of us from travelling overseas with our families, but what’s
stopping you from preparing for your next trip?
The luggage below (Fig. 2.4) contains 6 common body care products, Brand A to Brand F, that Singaporeans would bring overseas. Your mission is to check the ingredients lists of these products, and find out which ones contain microplastics
by comparing them to this list of microplastic materials here:
- Sodium Laureth Sulfate (SLS)
- Sodium Myreth
Sulfate
- PEG-8
- PEG-14
- Polyquaternium-7
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- Polyquaternium-10
- Propylene Glycol
- Carbomer
- Acrylates Copolymer
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If there is at least one ingredient that matches, the product has microplastics. E.g. Brand B has Sodium Laureth Sulfate, the list above has Sodium Laureth Sulfate, so Brand B has microplastics. There are 4 brands with microplastics and
2 without. Can you find them?

Figure 2.4: What’s in the Luggage?
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Figure 2.5: Ingredients of Various Brands |
[Answer: Items B,D,E and F have microplastics. The microplastics are those underlined in yellow! Did u guess them right?]
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Microplastics in Clothing
As mentioned earlier, some of our clothing contains microplastics. Microplastics come from a group of fabrics known as synthetic fabric. Examples of synthetic fabrics include Nylon, Polyester and Acrylic.
Here’s the bad news: Everytime
you wash a synthetic fibre clothing in the washing machine, 2000 or more microfibres can be washed off from that one synthetic fibre clothing. For 6kg of synthetic clothes, that’s 700000 microplastic pieces!

Figure 2.6: Did you know? Nylon, used to make the nylon “puffer” jackets on the left, is a type of plastic! The nylon fibers on the right are a type of primary microplastic that can fall off from the jacket during washing
An Experiment on Microplastics
How can we find out the number of microplastics different items produce? The Y4 students from Raffles Academy (RA) Biology were tasked to research on the number of microplastics produced from tyres and shoes. Below are the findings from Travis Tan, one
of the students from RA Biology.
Aim of Experiment
To find out whether shoes or tyres produce more microplastics after wear and tear
Plastic Content of Tyres and Shoes
Car tyres are made of 43% plastic, and they account for as much as 10 percent of overall microplastic waste in the world’s oceans. Shoes are made of around 40%-60% plastic.
How was the experiment conducted?

Figure 2.7: Diagram of Experiment
(Image from RA Biology students Yin Lye Ting, Tay Jo-Van and Ethan Leo)
1. Rub a strip of sandpaper on the car tyre and a shoe respectively for 20s, and allow the falling microplastic granules to collect on a plate.
2. Count the number of microplastics that have fallen on the plate after 20s.
3. Repeat the test on the car tyre and the shoe after 3 weeks of activity (driving the car, wearing the shoe etc.).
Experiment Findings and Conclusion

Tyres have more microplastics on them than shoes. This means that riding a car generally produces more microplastics, and contributes more to plastic pollution than walking with a pair of shoes!
Shouldn’t it be obvious then, that walking from one location to another will produce more microplastics than driving? Not necessarily! Time must be taken into account too, and a 5 minute drive to a destination, could be equivalent to a 30 min
walk to the same destination. The longer you walk or drive, the more microplastics the shoe or tyre will produce, but the results above do not account for the time the shoe or tyre was used. Hence, we can generally conclude that tyres produce
more microplastics than cars, but this is dependent on other factors as well.
Think about it! Why are there more microplastics on cars than tyres?
1. Cars are heavier than us, so there’s more friction from the tyres than the shoes when they rub against the ground, therefore they produce more microplastics.
2. Cars have a larger surface area, so there’s more wear and tear, meaning there will be more microplastics.

Figure 2.8: Eco-friendly Tip by Raffles EcoGryphons, a student-run initiative that improves RI’s conservation practices [Follow @ecogryphons on Instagram for more!]
Conclusion
Microplastics come from so many places, and it’s not just the normal plastic bottles, or plastic bags, that are producing microplastics. But what harm can microplastics do? Move on to the next page on the
“process of plastic pollution” to find out!
Time for a Quiz!!
Take this quiz to check how much you have learnt about plastics in general and their sources!!
Click on the quiz here: Sources of Microplastics
This quiz is open until Monday, 23 Nov 2020, 12noon.
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How are plastics harming the environment?
Click on Chapter 3 to find out!