If you’ve been following the debate in Sacramento over the use of foam cups and food containers in California, you probably have heard some rather outlandish allegations related to their safety.
After 40-plus years as a toxicologist, I can clearly state: There are no adverse health effects on humans from polystyrene foam food and drink containers. As California’s elected officials review various proposals, such as recycling these containers, the issue of safety can be set aside.
As we look at the safety of a polymer/plastic such as polystyrene, we should focus on the polymer, not its precursors. And polystyrene polymer is safe.
I suspect that much of the confusion over the safety of polystyrene stems from the similarity in names between polystyrene, a solid plastic, and styrene, a liquid chemical. Although the names sound familiar, polystyrene and styrene are different and have completely different properties. Styrene is a reactive substance that combines to form inert polystyrene. In other words, polystyrene does not have the properties of styrene.
This is true of all polymers (what we typically call plastics): they are different from the substances they are synthesized from. A common example is the difference between sugar and wood. Sugar is a substance with distinct properties. Join many sugar molecules together, and you get cellulose, the main polymer in wood.
So as we look at the safety of a polymer/plastic such as polystyrene, we should focus on the polymer, not its precursors. And polystyrene polymer is safe.
Some have questioned the potential impact of the tiny amount of styrene that can remain in the polystyrene polymer. The amount is minuscule and was difficult to detect until recent technological advances. The amount that potentially can transfer into foods is even smaller and is dwarfed by the amount of styrene that we all come into contact with in our daily lives.
A naturally occurring chemical, styrene was first extracted from the oriental sweetgum tree (also called levant styrax, after which styrene is named). The natural resin can be used as incense or to add a vanilla-like scent, while the oil has a woody aroma. Styrene’s chemical structure is similar to cinnamic aldehyde, the chemical component that creates cinnamon’s flavor.
Styrene is naturally present in several foods. It has been measured in foods that have not had contact with polystyrene containers. It is present in the highest concentration in coffee, cinnamon, beer and nuts.
In fact, styrene is everywhere in minute amounts. The air surrounding us always contains styrene from automobile exhaust, smoke, plant emissions and other sources. We also may recognize styrene by its distinctive odor (described by some as sweet) when using certain products such as latexes and paints.
The minute amount of styrene that may transfer from polystyrene containers into food or drink is about one-twentieth the overall amount we encounter every day when eating and breathing. Based on U.S. FDA’s safety calculations, this overall amount is orders-of-magnitude less than the agency’s “acceptable daily intake” of styrene.
In other words, there is no measurable risk. No governmental safety entity considers polystyrene a health risk. Numerous U.S. and state agencies, including the FDA, National Toxicology Program, National Institutes of Environmental Health Sciences, and Cal EPA, have stated such.
There are real risks out there that require our attention. And it’s important to make sure we use the best available science to measure and reduce those risks.
Polystyrene foam just isn’t one of those risks.
Ed’s Note: Toxicologist George Cruzan has a PhD in chemistry from The King’s College and a PhD in biochemistry from Purdue University. He has been a Diplomate of the American Board of Toxicology from 1980 to 2015. He has served as president of ToxWorks, a toxicology consulting firm, since 1995, during which time he occasionally provided professional services to the American Chemistry Council.