The EPA recognizes styrene (the primary building block of polystyrene) as a health threat to humans. It’s also considered a human carcinogen by the American Cancer Society.

Studies of workers exposed to high levels of styrene show an increased risks for lymphohematopoietic cancers, such as leukemia and lymphoma, and genetic damage in the white blood cells, or lymphocytes.

Polystyrene causes a mess in the environment. Because it is so lightweight and due to its propensity to fragment, polystyrene foam tends to drift away on currents of wind and water. Given its ubiquitous presence in disposable packaging, polystyrene is one of the most abundant forms of global pollution. And it poses a widespread threat to the health of wild animals and the ecosystems that they depend on.

It’s also a major component of the plastic debris in the oceans, according to the Ocean Conservancy. Currents and other marine action degrade polystyrene into carcinogenic microplastic particles that end up in our food chain. They are eaten by animals like fish, birds and turtles who mistake the particles for food, often leading to death from malnutrition.

Once used, almost all polystyrene food packaging has food residue and is not clean enough to be recycled. Less than one percent of polystyrene food packaging was recycled according to Business Insider.

Even if it were clean enough to recycle, less than 5% of foam packaging is actually polystyrene, and the rest is air, making it uneconomical to collect for recycling. The handful of manufacturers that collect polystyrene compress it to 1/10th of its original volume and sell the blocks to recyclers. The blocks can’t be used in new polystyrene products, so it becomes filler in other plastics making them virtually impossible to recycle.

Incinerating polystyrene for energy can release emissions containing more than 90 different compounds, including polycyclic aromatic hydrocarbons (PAHs), which may cause birth defects. When burned at lower temperatures typical of a campfire or a household fireplace, polystyrene can also produce PAHs, as well as carcinogenic styrene monomers and deadly carbon monoxide.

Reducing our use of products made from polystyrene will reduce health risks and environmental risks posed by this toxic polymer, of which there are many.