Should We Worry About Microbeads?

This sea butterfly larvae is one of those zooplankton susceptible to eating plastic microbeads. Jeff Rottman/Photolibrary/Getty

Among the negative consequences of our increased reliance on plastics, water pollution by plastic is emerging as a serious problem. Microplastics are small fragments of plastic material, generally defined as smaller than what can be seen by the naked eye. As plastic items in the environment become degraded, they yield increasingly small particles that eventually can be classified as microplastics.

A more recent type of trash in the oceans consists in tiny polyethylene spheres, or microbeads, increasingly found in many consumer products. Microbeads are very small, uniformly sized and shaped plastic beads. Their diameter can be a few dozen to a few hundred micrometers. By comparison, a sheet of copy paper is about 100 micrometers thick. These microplastics do not come from the breakdown of larger pieces of plastic, but instead are engineered additives used in cosmetics and personal care products, most often in face scrubs and toothpaste. They are most often used in skin care products and toothpaste. They are also used as sandblasting media for light industrial applications. After they are used, microbeads wash down drains, pass through water treatment plants, and end up in freshwater and marine environments.

Environmental Effects of Microbeads

  • Many persistent organic pollutants (or POPs) float around lakes and oceans at low concentrations. These include clearly harmful chemicals like certain pesticides, PCBs, DDT, and dioxins. The hydrophobic nature of POPs concentrates them on the surface of the tiny plastic particles. Microbeads may be small, but they have a lot of surface area by volume, providing ample space for dangerous molecules to attach themselves. Microbeads end up with pollutant concentrations several times higher than that of the surrounding water. Marine animals mistakenly feed on the microplastics, and at the same time ingest the toxic pollutants. The chemicals accumulate in the animal tissues and then increase in concentration as the pollutants are transferred up the food chain.
  • Beside the associated chemical loads, ingested plastic materials is damaging for the smaller marine organisms, as they can lead to digestive blockage or internal damage from abrasion. Even millimeter-long zooplankton will eat microbeads. There is still much research needed to properly evaluate this issue.
  • Effects on humans are suspected but unknown at this point. Of particular concern is the endocrine disrupting nature of plastics, especially since microbeads are small enough that they probably can travel relatively far inside a human body.

Legislative and Industry Responses

Recently, dental hygienists have started noticing tiny colored polyethylene beads stuck between the gums and teeth of patients. It turns out those were microbeads added to toothpaste to provide color. There is no scientific evidence yet suggesting that these plastics are harmful, but dental professionals have expressed concern that the beads may help trap bacteria, leading to tooth decay or gum disease. In response, some major toothpaste manufacturers have pledged to phase out their use of microbeads, which will also reduce their input into our aquatic systems.

At the state level, Illinois enacted the first ban on cosmetics containing microbeads. Colorado, New Jersey, and Maine followed, and bills are in the works in many other states.

Sources

Eriksen et al. 2013. Microplastic Pollution in the Surface Waters of the Laurentian Great Lakes. Marine Pollution Bulletin.

Phillip, A. 2014. Why Dentists Are Speaking Out About the Plastic Beads in your Toothpaste.

Washington Post.