Paper straws are touted as an eco-friendly alternative to their classic plastic counterpart, but according to new research, paper straws still contain long-lasting and potentially toxic chemicals.
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).
PFAS were found in the majority of the straws tested and were most common in those made from paper and bamboo, according to the research, which was published in the peer-reviewed journal Food Additives and Contaminants.
PFAS are commonly used in everyday products, from outdoor clothing to non-stick pans, that are resistant to water, heat and stains. However, they are potentially harmful not only to us, but the wildlife and environment, due to their very slow breakdown that can persist over thousands of years - a property that has led to the name 'forever chemicals'.
The damaging effects PFAs can have on our health have been well-documented. A research paper in 2021 noted that epidemiological studies have revealed associations between exposure to specific PFAS and a variety of health effects, including altered immune and thyroid function, liver disease, lipid and insulin dysregulation, kidney disease, adverse reproductive and developmental outcomes, and cancer.
"Straws made from plant-based materials, such as paper and bamboo, are often advertised as being more sustainable and eco-friendly than those made from plastic," said researcher Dr Thimo Groffen, an environmental scientist at the University of Antwerp, Belgium, who was involved in the study.
"However, the presence of PFAS in these straws means that's not necessarily true."
A growing number of countries, including the UK, Belgium, and New Zealand, have banned or are in the process of banning single-use plastic products, including straws - with plant-based versions becoming popular alternatives.
When a recent study found PFAS in plant-based drinking straws sold in the US, Dr Groffen and his colleagues wanted to find out if the same was true of those on sale in Belgium.
To explore this further, the research team purchased 39 different brands of straws made from five materials: paper, bamboo, glass, stainless steel and plastic.
The straws, which were mainly obtained from shops, supermarkets and fast-food restaurants, then underwent two rounds of testing for PFAS. The majority of the brands (27 out of 39, or 69 percent) contained PFAS, with 18 different PFAS detected in total.
The paper straws were most likely to contain PFAS, with the chemicals detected in 18 of the 20 brands tested (90 percent). PFAS were also detected in four out of five of the bamboo brands (80 percent), three out of four of the plastic straws (75 percent), and two of the five brands selling glass straws (40 percent). They were not detected in any of the five types of stainless steel straws tested.
The most commonly found PFAS, perfluorooctanoic acid (PFOA), has been banned globally since 2020. Also detected were trifluoroacetic acid (TFA) and trifluoromethanesulfonic acid (TFMS), "ultra-short chain" PFAS which are highly water soluble, meaning the chemicals could leach out of the straw and into the beverage.
The research team noted the concentrations were low and as straws are not typically an everyday item, the chemicals pose a limited risk to human health. However, PFAS can remain in the body for many years and concentrations can build up over time, Dr Groffen added.
"Small amounts of PFAS, while not harmful in themselves, can add to the chemical load already present in the body," he said.
It isn't known whether the PFAS were added to the straws by the manufacturers for waterproofing or whether they were the result of contamination, potentially via the soil the plant-based materials were grown in and the water used in the manufacturing process.
Despite this, the presence of the chemicals in almost every brand of paper straw means it's likely that PFAS were, in some cases, added during manufacturing as a water-repellent coating, the researchers said.
The study's limitations include not looking at whether the PFAS leach out of the straws and into liquids.
"The presence of PFAS in paper and bamboo straws shows they are not necessarily biodegradable. We did not detect any PFAS in stainless steel straws, so I would advise consumers to use this type of straw - or just avoid using straws at all," Dr Groffen said.
