A short talk I delivered to a school on the possible effects of microplastics.

1. A Pint Of Plastic:
How much plastic are you really eating?
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Peter King (p.m.king@bath.ac.uk)
PhD Candidate
Department of Economics, University of Bath, UK

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Motivation

3. • I’m doing my PhD on valuing marine
pollution.
• Motivated by Blue Planet II.
• How much plastic are you really eating?
• Well a 2019 WWF Report claimed
humans were ingesting 5 grams of
microplastics per week (~179
particles).
• Microplastics are small plastic
particles up to 5mm across
• Average weight: 3.65 micrograms
• This talk discusses the sources, effects
(environmental and health) and fate of
microplastics 3
Motivation

4. • Economic theory: what are people willing to pay for less
pollution?
• `Primary’ microplastics:
• Added to products for a function:
• Cosmetics/personal care products
• Fertilisers
• Wearing of tyres, textiles, paints.
• Finds their way via sewage to water treatment plants to the
sea.
• `Secondary’ microplastics:
• Larger plastic items that have broken down in the ocean.
• Bags and bottles
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Background

5. • Simple plastic market:
• A typical single-use 2L plastic bottle: 0.1-0.2kg of plastic or
2,000 microparticles.
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Secondary Microplastics

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Primary Microplastics

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Primary Microplastics
• Cosmetic products:
• Some types of microplastics
added to cosmetic products,
such as scrubs, exfoliators
and moisturizers, were
banned in the UK in 2018
• Other types of microplastics
added to personal care
products, such as toothpaste,
shower gel, shampoo,
sunscreen and deodorant,
still in use.

8. • Microplastics have been ingested by more than 250 species
of marine life:
• Seabirds: mistake floating plastics for prey
• Fish: easily entangled in or eat plastics
• Smaller animals: higher levels of ingestion.
• Microplastics in the sea can absorb chemicals, helpful or
harmful, and passing those on.
• Once ingested microplastics accumulate in the gut and then
may be passed through the food chain
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Environmental Effects

9. • The physical risk of microplastics blocking breathing is unlikely in humans
but more possible in fish and birds.
• Possible chemical effects of inflammation and hormone changes may be
possible - only at extremely high levels.
• Is there any immediate problem?
• "Concentrations of microplastics in the environment are forecast to
progressively increase as they are almost impossible to remove once
dispersed within the environment and persist almost indefinitely”.
• How serious are the effects?
• "Despite the environmental concerns about some of the chemicals
used in plastic manufacture, it is important to emphasize that evidence
for effects in humans is still limited and there is a need for further
research”.
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Health Effects

10. • The European Chemicals Agency has proposed a restriction
on all microplastics added to products.
• Would make products more expensive and less effective and
the reduction in environmental and health risks may be small.
• My research looks at how much consumers are willing-to-pay
for microplastic-free products.
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My contribution

11. • Thanks for listening!
• In summary: we might have a problem in the future.
• More on my research:
• www.bit.ly/PeterKing
• More on this presentation:
• https://pintofscience.co.uk/blog/a-pint-of-plastic/
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Summary