Reusable plastic water bottles release numerous chemicals into the drinking water they contain. A Danish study just published in the Journal of Hazardous Materials tested them by simulating different conditions of daily use by athletes.
Migration-proof plastic water bottles
Researchers at the University of Copenhagen conducted three different chemical migration experiments using newly purchased clear biodegradable polyethylene water bottles and water bottles used for about a year (2-3 times a week), in red polyethylene and in clear biodegradable polyethylene.
As a comparison item, they used glass bottles, which are known to be free from the risks of particle migration.
First experiment
In the first experiment, freshly purchased water bottles from a Danish sporting goods store were rinsed once with tap water, drained and then refilled with new tap water, capped and stored for 24 hours at room temperature (about 21 °C), protected from sunlight.
Second experiment
In the second experiment, all bottles (new rinsed bottles, used plastic bottles, and glass bottles) were placed in the dishwasher upside down, separating lids and bottles.
A 60-minute wash program was started, with temperature up to 65 °C . A standard household dishwasher tablet purchased from a Danish retailer was used as soap, with the ingredients described as 15 to 30 percent bleaching agents and nonionic detergents, polycarboxylates and phosphonates < 5 percent.
The day after the washing cycle, the bottles and flasks were filled with tap water and stored for 24 hours at room temperature (21 °C).
Third experiment
In the last experiment, the bottles and water bottles taken out of the dishwasher were rinsed thoroughly by simulating typical family washing. Five times they were filled with cold tap water, capped, shaken, and drained.
After completion, all were refilled with tap water and stored for 24 hours at room temperature (21 °C).
The result
Overall, more than 400 plastic-related compounds and more than 3,500 compounds related to dishwasher soap ‘appeared’ in the water analysis.
Washing in the dishwasher increased the migration of chemicals. Even after rinsing with water, more than 400 compounds continued to migrate.
The highest level of contamination is from used water bottles refilled immediately after washing in the dishwasher.
Predictably, compared to plastic, glass bottles absorb less of the substances in the detergent.
Endocrine disruptors and carcinogens
In new flasks, most of the identified compounds are oligomers of plasticizers.
For the flasks used, the chemicals in migration identified are as plasticizers, antioxidants, and photoinitiators.
Three toxic chemicals stand out among the identified photoinitiators :
– Irgacure 369 (CAS 119313-12-1), a known endocrine disruptor and added to the REACH registration list as a carcinogen, mutagen or reproductive toxicant,
– 4-Methylbenozophenone (CAS 134-84-9) a carcinogen,
– anthraquinone (CAS 84-65-1) whose degradation products may be carcinogenic.
Conclusions
According to the authors, ‘the study raises the question of whether plastic bottles are suitable for reuse, especially when labeled as biodegradable plastic.’
In fact, the use of biodegradable plastic does not mean that the bottles are necessarily made of natural compounds. ‘Instead, it can be assumed that plasticizers will more easily migrate into consumers’ drinking water when biodegradable plastic bottles slowly degrade during use.’
Marta Strinati
Notes
Selina Tisler, Jan H. Christensen, Non-target screening for the identification of migrating compounds from reusable plastic bottles into drinking water, Journal of Hazardous Materials, Volume 429, 2022, 128331, ISSN 0304-3894, https://doi.org/10.1016/j.jhazmat.2022.128331.
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
