What are microplastics?
Microplastics are defined as plastic pieces that are between 1 micrometre (one millionth of a metre) and 5 millimetres in size. Nanoplastics are particles that are smaller than 1 micrometre.
All plastics are manufactured industrially. There is no such thing as “natural” plastic. Plastic consists mainly of carbon and hydrogen, which are bound together in long chains called polymers.
Scientists distinguish between primary and secondary microplastics. Primary microplastics are small plastic particles that are intentionally manufactured in this size for use in cosmetic products or as abrasives. Secondary microplastics result when larger plastic products – such as plastic bags, bottles or fishing nets – break down into smaller plastic pieces.
Where do microplastics come from?
About 75 per cent of all plastics that wind up in the ocean originate on land and are transported via rivers. Insufficient garbage handling makes rivers in Asia and Africa particularly vulnerable.
Sources of plastic debris (including microplastics) in the ocean
Sea-based sources include:
- Merchant shipping – rope, galley waste
- Fishing – nets, boxes, rope, wrapping bands, galley waste
- Aquaculture – nets, floats, rope
- Offshore oil and gas platforms – galley waste, sewage-related
- Cruise ships – galley waste, sewage-related (may be equivalent to a medium-sized town)
- Recreational boating – galley waste, sewage-related
Land-based sources include:
- Coastal tourism – packaging, cigarette filters
- Population centres – sewage- related, storm drains, street litter
- Horticulture/agriculture – plastic sheeting, tubing
- Poorly controlled waste sites and illegal dumping – all waste types
- Industrial sites – plastic production and conversion, packaging
The effects of the sun, wind and waves, coupled with abrasion from sand and stone, break down the plastics into smaller fragments and create huge amounts of microplastics and nanoplastics.
Why should we be concerned about microplastics?
Three attributes of microplastics in particular give cause for concern:
- a) Plastics are difficult or impossible to get rid of.
- b) Microplastics can harm aquatic organisms and animals.
- c) We don’t know enough about how microplastics can affect people.
Plastic is designed to be highly durable. This means that plastic breaks down very slowly or not at all in nature. The result is that plastic accumulates rapidly, especially in the ocean. It may be possible to remove larger plastic particles from the ocean, but microplastics already there are impossible to get rid of.
Animals that ingest larger plastic particles are adversely affected. A good example is the dying whale found last year with 30 plastic bags in its stomach in Western Norway. Plastic debris blocked its intestines so the whale was no longer able to digest food.
As larger animals consume smaller organisms, the microplastics can work their way up the food chain. In other words, people also become susceptible to ingesting microplastics when we eat fish and seafood.
Ingesting microplastics through foods that we consume, such as fish or other seafood, has already been mentioned.
We also breathe in and swallow microplastic particles from artificial turf, in airborne dust from roads or from house dust in our homes.
We can absorb them via products like cosmetics and toothpaste, or through particles from plastic kitchen utensils or food packaging. Microplastics have also been detected in drinking water, albeit in small quantities.
We still don’t know for sure whether microplastics or plastic chemicals are found in vegetables and fruits from plants that have been fertilized with sludge from water treatment plants.
What effects do microplastics have on people?
Scientists still know very little about how microplastics affect people. But experiments carried out with marine organisms such as copepods and algae can give us some indications.
Experiments with copepods, oysters, scampi and crabs show that marine animals consume less food when they ingest microplastics. This reduces their energy levels, which in turn can lead to a lower immune response, less growth and fewer offspring.
Chemicals leached from plastics can cause hormonal disturbances that result in fewer offspring, abnormal development and disease.
How can I help reduce microplastic pollution?
Help keep the environment free of plastic waste. By picking up one discarded plastic bag you remove millions of potential microplastic particles.
Make conscious choices as a consumer. Consider alternative products if the packaging tells you that the product contains microplastics.
Can you wash clothes made from plastic fibres a little less often? Bring cloth shopping bags along instead of using plastic bags.
Avoid buying single-use plastic products. Sort your waste and recycling.
Why are microplastics in the ocean receiving increasing attention?
Marine litter – especially plastic debris in the ocean – is a major global environmental issue.There is growing awareness by the scientific community, governments, industry, the general public, the media and non-governmental organizations (NGOs) of the potential for microplastics to harm the environment.The scale of the problem has driven a large number of scientific investigations; initiatives at governmental, regional and international level; and activities led by NGOs, including education and awareness raising, lobbying, removal of litter from shorelines, and ocean expeditions.
While a mounting body of scientific evidence suggests that society should be concerned about the potential effects of microplastics in the ocean, the evidence is as yet insufficient to quantify the nature and full extent of these effects.
The physical effects of plastic debris due to both entanglement and ingestion have been clearly demonstrated. However, it has proved more difficult to demonstrate these effects for microplastics.
Studies have shown that microparticles can be ingested by filter-feeding marine organisms such as oysters and mussels.They have been observed to close the gut wall and induce a reaction within the tissue. On a different scale, surface-skimming baleen whales such as the endangered NorthAtlantic right whale (Eubalaena glacialis) feed on copepods and other small invertebrates by filtering enormous volumes of seawater. It is possible that microplastics in the seawater present an additional stressor if they affect the filter-feeder system inside the whale’s mouth