What are Microplastics, and Why are they Dangerous?

Plastic is widely used in many products. It’s convenient, durable, and affordable, right? This durability, or persistence, is part of what makes it so bad for the environment. When plastic gets out into nature, it takes hundreds of years to decompose, or break down into small parts. Macroplastics, or large pieces of plastic, are dangerous: animals may eat them or get entangled within them. Microplastics, pieces of plastic smaller than 5 mm in size, are quite harmful as well. They are classified as primary and secondary. Primary ones were created to be small- think microbeads used in face wash or microfibers used in clothing. Secondary refers to pieces created as a larger original piece, such as a water bottle, breaks down. All the while, sun and UV light simply fragment it into smaller and smaller pieces, or secondary microplastics.

Litter often gets into drains, which eventually lead to oceans- microplastics are no exception. There, they wreak havoc on the health of marine animals such as fish and oysters- some effects involve physical injuries and disruptions of body systems. Often, animals cannot distinguish between plastic and actual food. They’ll just go for the plastic when they’re hungry! This is dangerous: it leads to wounds, intestinal blockage, and poor nutrition(they eat less food as they feel full already). Beyond that, microplastics can influence animals’ development, metabolism, immunity, and fertility. You might be wondering… HOW can some little pieces of plastic make such a difference? Researchers are still studying this, but it likely has something to do with chemicals added to the plastic. For instance, Bisphenol A (BPA) is frequently added to food packaging, and can disrupt hormones.

As if they weren’t bad enough already, microplastics can also spread disease. They serve as little rafts for unsavory pathogens and dangerous toxins! Bacteria including Aeromonas salmonicida and Vibrio species can grow on microplastics; A. salmonicida causes illnesses in salmonid fish, while Vibrio species are responsible for diseases such as cholera. Chemicals including polycyclic aromatic hydrocarbons and fertilizers, and heavy metals like copper and zinc all bind to microplastics. It is uncertain whether this binding is harmful or beneficial. It is very dangerous for animals who might consume the plastic. However, if the substances bind to the plastics, there are less of them floating around in the water. Given this uncertainty, there are opportunities for further research in this field.

Microplastics

Picture Credit: washingtonpost.com