"Plastic in tea water", "plastic tea bags should be banned", "infusion with microplastics", "tea bags release billions of microparticles". A Canadian study accepted on August 12, 2019 alerted the presence of millions of plastic microparticles when plastic tea bags are infused at 95°c for 5 minutes. But what are these plastic microparticles and why do they react ?
If there is one known way of drinking tea, it is the use of tea bags. These small bags with a string and a small label are made from different materials: paper, cotton and especially plastic. The advantage of plastic bags is that they can be mass-produced at low cost and can take different shapes. From the simple pouch to the more qualitative pyramid-shaped "crystal" bags, everything is possible with plastic. And this plastic is made of microparticles.
But what exactly is a plastic microparticle ?
An ant measures a few millimetres. A microparticle is a thousand times smaller than an ant. These are particles invisible to the naked eye that can be released from the plastic. In the case of a plastic tea bag immersed in hot water, the microparticles will be released from the plastic and remain suspended in the water. This cannot be prevented regardless of the water temperature.
So if we encounter this all the time, what's the problem?
At the present time, plastic poses great questions for human health, especially in the food industry. Various scientific works have already proven the presence of plastics in certain packaged foods (1) or in the water in plastic bottles (2). A report issued in 2019 by the CIEL company (3) summarises the information we know about plastics in humans.
The toxicity risks linked to the material itself are numerous: cardiovascular, renal, reproductive, neurological, respiratory, carcinogenic, etc). There are other sources of risk carried by plastic microparticles. Those that are released in liquids would capture on average 4% of the toxic additives used in the manufacture itself. One of the best known, bisphenol A, was the subject of a health safety report updated by ANSES in 2018 (4). Since 2015, this additive has been banned in the manufacture of baby bottles or water bottles.
So what have these researchers done ?
In the name of science ... They went to the supermarket to buy four different brands of tea bags (we will not know the names). They emptied the tea bags, rinsed them three times to remove all traces of tea and brewed them for 5 minutes at 95°C. Once the infusion was made, their study was carried out in three stages :
- They cut samples of tea bags after the infusion and proceeded to different types of filtration to recover the water and plastic fibres from the bags. The recovery of the fibres allowed them to see if the structure of the mesh structure of the sachet remained intact and the recovery of the water allowed them to validate the presence and size of microparticles. They compared pieces of fibres before and after infusion by observation with different types of microscopes. The goal: to validate the presence of microparticles.
- Each molecule has a "signature". It corresponds to the proportion of each component of the molecule. It is possible to detect each component of a molecule and its proportion in order to identify which molecule we are dealing with. The goal is to prove that the microparticles recovered are plastic and to obtain information about the quantity of microparticles in the water.
- To check the toxicity of a molecule, there are several solutions. Here, the authors exposed a species of plankton (Daphnia magna) to the plastic microparticles in the tea bags. In this plankton, changes in morphology and a lower swimming speed are evidence of a toxic effect. The aim: to provide initial proof of the toxicity of the microparticles.
What conclusion can be drawn from this ?
This team of researchers is the first to have demonstrated that plastic tea bags infused at a conventional time for a large number of tea drinkers release plastic microparticles (nylon and PET, two common plastics). The amount that is released is at least 3,000 times greater than the amount that can be found in foods packaged in plastic such as table salt. These microparticles are potentially toxic, in this case to living organisms such as plankton (morphological deformation and lower swimming speed).
This study is interesting because it is based on a consistent pattern of tea consumption with a wide audience and this for different types of tea bags (including crystal tea bags which are considered the best on the market).
Another more worrying fact is that they washed the tea bags three times. Imagine without washing what this can look like... Unfortunately, they could not measure the amount of microparticles without washing because the tea molecules could have disturbed their measurements.
However, we have to keep in mind that we have no way of knowing the daily amount of plastic that is non-toxic to the human body. Today there are many alternatives to avoid using plastic bags. Cotton bags are becoming more and more popular (although infused cotton should also be tested...). Bulk is probably the least risky solution, although more restrictive.
In any case do not burn your bags right away, consume with discernment !
For English speakers, you can obtain the publication on researchgate. Just click on this link and then click on "Download full-PDF". A researchgate subscription window will appear. Simply remove it by clicking on the cross. A window for saving the publication as a PDF will then app
Comentarios