These products, commonly advertised as “more sustainable and eco-friendly than plastic ones,” contain substances that “can persist for thousands of years.”

Paper straws considered “green” because they are not made of plastic contain long-lasting and potentially toxic chemicals, according to a new study published in the journal ‘Food Additives and Contaminants‘.

In the first analysis of its kind in Europe, and only the second in the world, Belgian researchers tested 39 brands of straws for the group of synthetic chemicals known as poly- and perfluoroalkyl substances (PFAS).

The study found PFAS in most of the straws tested, especially those made of paper and bamboo. PFAS are used to make everyday products, from outerwear to non-stick pans, resistant to water, heat and stains. However, they are potentially harmful to people, wildlife and the environment.

They break down very slowly over time and can persist for thousands of years in the environment, a property that has led to their being known as “forever chemicals.”

They have been associated with a number of health problems, including reduced response to vaccines, lower birth weight, thyroid disease, increased cholesterol levels, liver damage, kidney cancer, and testicular cancer.

“Straws made from plant-based materials, such as paper and bamboo, are often advertised as being more sustainable and eco-friendly than plastic straws,” says researcher Dr. Thimo Groffen, an environmental scientist at the University of Antwerp in Belgium, who is participating in this study.

“However, the presence of PFAS in these straws means that this is not necessarily true,” he adds.

A growing number of countries have banned the sale of single-use plastic products, including drinking straws, and plant-based versions have become popular alternatives.

The straws, which were obtained primarily from convenience stores, supermarkets, and fast-food restaurants, were subjected to two rounds of testing for PFAS. The majority of brands (27/39, 69%) contained PFASs, with 18 different PFASs detected in total.

Paper straws were the most likely to contain PFAS, with chemicals detected in 18/20 (90%) of brands tested. PFAS were also detected in 4/5 (80%) brands of bamboo straws, 3/4 (75%) of brands of plastic straws, and 2/5 (40%) brands of glass straws. They were not detected in any of the five types of steel straw analyzed.

The most commonly found PFA, perfluorooctanoic acid (PFOA), has been banned worldwide since 2020. Trifluoroacetic acid (TFA) and trifluoromethanesulfonic acid (TFMS), highly water-soluble “ultra-short-chain” PFASs, were also detected, therefore that could leak from the straws into the drinks.

The PFAS concentrations were low and, considering that straws are used only occasionally by most people, they pose a limited risk to human health. However, PFASs can remain in the body for many years, and concentrations can increase over time.

“Small amounts of PFAS, while not harmful in and of themselves, can add to the chemical load already in the body,” Groffen cautions.

It is not known if the PFAS were added to the straws by the manufacturers to make them waterproof or if they were the result of contamination. Potential sources of contamination include the soil in which the plant materials were grown and the water used in the manufacturing process.

However, the presence of the chemicals in almost all brands of paper straws means that they were likely used as a water-repellent coating in some cases, the researchers say.

Groffen concludes that “the presence of PFAS in paper and bamboo straws demonstrates that they are not necessarily biodegradable. We did not detect any PFAS in stainless steel straws, so I would advise consumers to use these types of straws, or simply avoid using them.”