Toxins in the news: Microplastics

What are microplastics?
The term “microplastics” refers to plastic and polymer debris with a diameter ranging from one micrometer up to five millimeters. This range of sizes includes debris that is smaller than the width of a human hair up to pieces that are as large as a pebble. Microplastics can form when larger plastic waste, such as drink bottles, break down into smaller chunks. Another source of microplastics are ‘microbeads’, or small pieces of plastic that are sometimes added to personal care products. Certain brands of exfoliating face cleansers or toothpaste have microbeads in them.

How do they get into the environment?
While personal care products are one source of microplastics, their use in cosmetic products is starting to be phased out. Microbeads are now banned in products made in the US and the UK is committed to implementing a ban by October 2017. There is currently no ban in the EU but the trade body Cosmetics Europe is encouraging its members to phase out microbeads by 2020.

The primary source of microplastics in the environment comes from the physical break-down of plastic waste. The amount of plastic generated each year has increased by a factor of four from 2004 to 2014, and it is predicted that by 2050 we could be making up to 33 billion tons of plastic per year. Because many of these plastic products are for short-term use, like product packing materials or single-use packaging, a large amount of plastic will be disposed of shortly after use.

Plastic is so used because of its durability. Larger pieces of plastic such as bottles and containers break down into smaller pieces, but these small pieces never truly degrade. Unless plastic waste is incinerated, it will continue to cycle through the environment. Because of this, microplastics and plastic litter can be found in a wide range of places: parks, prairies, forests, rivers, lakes, estuaries, coastal areas, the open ocean, and even deep sea sediments. 

Why are scientists concerned?
Once microplastics enter the environment, plastics are eaten by animals, especially fish and birds. Recent studies showed that up to 90% of all seabirds have eaten plastic, and plastic could even be found in over half of the world’s sea turtle population. Many plastic pieces can simply be ejected from the body as waste, but too much plastic can cause serious harm to animals. Larger microplastic pieces can cause physical damage to an animal, such as internal cuts and bleeding, inflammation, and lower energy levels from consuming too much inedible and indigestible material.
 
The smallest pieces of microplastic will be eaten by animals such as diatoms, copepods, and brine shrimp, while larger pieces are consumed by shellfish, starfish, crabs, and fish such as catfish, perch, and trout. Smaller pieces eaten by animals lower on the food chain can then build up over time as these animals are eaten by larger predator species, causing microplastics to remain and even increase over time through the food chain.
 
An additional concern with animals eating microplastics comes from the chemical additives included in many plastic products that can be toxic. Certain chemicals are added to plastics for increased elasticity or rigidity, including bisphenol A, phthalates, polybrominated diphenyl ethers, and metals. Unlike the plastic polymers these chemicals are added to, additives are not as stable and can break apart from the plastics. Even if a fish or a mussel is unharmed by eating small pieces of plastic, the toxic chemicals attached to the plastic can get into the animal and cause serious toxic damage.  
 
Should I be concerned?
Because plastics are so widespread in the environment and are known to be consumed by a large number of animals, scientists worry that traces of microplastics can be found in humans. This field of research is still growing, however, and there haven’t yet been any large-scale studies. Scientists are interested in looking at microplastic levels in humans and determining if differences in seafood consumption correspond with microplastic levels in the body.

But because this field is still new, there is a lot we still don’t know about microplastics. Many of the uncertainties are around the exact amount of microplastics that fish (and humans) might eat. This uncertainty comes from the fact that it is difficult to quantify the amount of plastic when there is such a broad range of sizes and shapes. Microplastics also represent a wide range of materials, all of which have different added chemicals, making it more of a challenge to determine what, exactly, we could be potentially exposed to.

Research progress is being made across the world to help answer these questions. A recent review highlighted the results of over 80 studies in aquatic environments which looked at both the distribution of plastic waste and the impacts of microplastics on animals and plants. The authors also identified ‘hot spots’ of microplastic pollution across the world. Other questions that scientists are working to answer will help policymakers determine the best course of action on national and international levels. These questions include how microplastics move in the environment, what types of polymers are the most common, and how ecosystems as a whole are affected by microplastics.

What can I do?
Using less plastic is a small yet simple start towards solving part of the problem. If you live in a country that does not ban microbeads in cosmetics, see if your current personal care products have added microplastics—and if they do, explore alternative products instead.

Local recycling and plastic reduction efforts have also been effective at decreasing plastic waste. In San Jose, CA, a 2012 plastic bag ban reduced the amount of plastic waste in the city by up to 89%. Keep a reusable bag with you while shopping and promote similar shopping initiatives in your own community.
 
If you want to become proactive in plastic waste reduction efforts in the US, NOAA maintains a list of clean-up events, teaching guides, and resources for recreational users as part of its Marine Debris program. NOAA is also the government organization in charge of awarding research grands, education, and clean-up efforts around microplastics and marine debris—so let your congressional representatives know that you support NOAA and don’t want their efforts to be hindered by budget cuts or government scientist gag orders. 

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