Tiny fragments, fibers and nanometer particles of plastic are hiding in food and beverages. Here’s where.
Microplastics are now widely found in food and beverages. Their origin is varied. Plastic polymers, which flake into more than microscopic fibers and particles, are used in packaging, cosmetics, textiles, for example. Everyday objects through which we unknowingly continue to spread invisible pollutants.
Plastic debris invades the seas, and the organisms that live in them. They arrive on our plates through fish and salt. But even outside the seas, the invasion of plastic particles is extensive. It travels through mineral water, beer, honey. And it is even found in chicken meat.
‘Concerns are growing about how plastic is polluting our environment. Great attention has recently been paid to how microplastics – fragments as large as 5 millimeters to 100 nanometers (a nanometer is equal to one billionth of a meter, one millionth of a millimeter, ed.) – Are penetrating the seas and the creatures that inhabit them. With the consequence that these oceanic microplastics enter our food chain, and thus our bodies. But fish and shellfish are not the only food containing microplastics. And other food sources that do not come from the sea may be of much greater concern
‘, they state in an
article
on the subject Christina Thiele and Malcolm David Hudson, researcher and professor, respectively, at the British University of Southampton.(1)
From the sea, bitter mussels and plastic fish
According to a
study published in 2014 in Enviromental Pollution.
, a portion of farmed mussels served in Europe could contain about 90 microplastics (understood as fragments no larger than 1 mm). As a result, large consumers of these shellfish could ingest up to 11 thousand microplastics per year.
Emblematic is the studio accomplished by a team Of Portuguese researchers in 2015. Tissue analysis of 263 fish caught in Lisbon showed the presence of microplastics in 19.8 percent of cases. 1 in 5.
The most contaminated fish are those caught in trawl nets in the Lisbon metropolitan area and near the Tagus River estuary, an estuary on the ocean coast, pertando characterized by the entry of the sea into the first section of the riverbed. One-third of the fish tested positive in the controls had ingested more than one type of plastic polymer including polypropylene, polyethylene, alkyd resin, rayon, polyester, nylon, and acrylic.
The bulk of the microplastics found (65.8 percent) were fibers, found mainly in demersal fish. That is, those that swim and feed on the seabed, such as cuttlefish, cod, hake, mullet, and sea bass.
In slightly more than one-third of the cases, however, the polymers were in particle form, especially in pelagic, i.e., migratory fish, those that feed in open waters, such as tuna, swordfish, and lanzards (
Scomber Japonicus
). The latter-a type of mackerel that is very common on Mediterranean tables in the summer, when it approaches the coast for spawning-was found to be the most contaminated.
From the gut to the liver, the migration of microplastics
Studies on microplastic contamination of marine life have focused, predominantly, on the analysis of fish stomachs and intestines, parts that are normally discarded before consumption. However, as shown for the first time by a
study
from the University of Liege, microplastics migrate to various areas in the body, transferring from digestive tissue to other parts of the body.
Belgian researchers have detected accumulations of various microplastics-mostly polyethylene-also in the liver of anchovies (or anchovies), sardines and herring. In anchovy liver, these contaminants were relatively large in size, ranging from 124 to 438 µm (one micrometer is equal to one thousandth of a millimeter). A sign, according to scholars, of a high level of contamination.
Canned sardines
Surprisingly, the presence of microplastics has also been detected in canned fish, which are usually gutted and cleaned. In a search conducted by French-Malaysian researchers, canned sardines and sprats (sardine-like fish) from 20 different brands were analyzed. Microplastics were found in 4 of them, which researchers do not know whether to attribute to ineffective fish cleaning or contamination that occurred within the processing plants. By consuming canned fish contaminated with microplastics, the researchers conclude, you risk ingesting up to 5 pieces of plastic per year. The plastic particles found are almost always PP and PET.
Salt to plastic
Another source of microplastics is sea salt. A 2015 Chinese study analyzed 15 brands of salt sold in Chinese supermarkets and found up to 681 plastic fragments per kg of sea salt. Polyethylene terephthalate (PET), polyethylene and cellophane thus end up on our plates.
‘By consuming the maximum recommended daily intake of salt of 5 grams per day, up to three microplastics are ingested. But many people ingest much more than the recommended amount’, note the Southampton scholars, who also point out the difficulty of comparing studies on microplastics. Indeed, in the absence of unified standards, some researchers consider only microfibers (from synthetics such as polyester), others only fragments larger than 200 micrometers in size.
More recent (late 2017) is the
study
by a Turkish researcher, who analyzed 16 brands of table salt detecting
16-84 particles per kg in sea salt, 8-102 in lake salt, and 9-16 in rock salt. The most common plastic polymers were polyethylene (22.9 percent) and polypropylene (19.2 percent).
Styrofoam chicken
The spread of plastic fragments in the marine environment is widely known. There is less widespread awareness of their penetration into the non-sea environment and consequently into foods from it. Yet, the seeker finds. A team of Mexican researchers analyzed chicken gizzards, the main ingredient in a typical dish widely consumed in that country. It emerged that each chicken gizzard contained an average of 10 microplastics. In almost all (91.4%), the plastics ingested by the chickens were residues of PE bottles, reveals the studio, while 6.9 percent was fiber and 1.7 percent was polystyrene. The transmission of such plastics is facilitated by the home preparation mode. Interviewed by the researchers, 7 out of 10 women reported that they only wash the gizzard externally, then cook it in the broth and finally cut it to place over rice.
Honey and plastics, discordant studies
Even honey can carry microplastics in our diet. One studio German in 2015 identified them in 47 samples of various origins. Among them, in addition to 6 Italian honeys, there are 10 honeys of Swiss origin. The provenance in this case is intriguing, as Swiss researchers in a similar
study
conducted two years later found no significant microplastic contamination in the 5 Swiss honeys analyzed.
Beer, a sip of plastic
In 2014, beer was also found to be polluted by microplastics. He sought them out and found a team of German researchers in all 24 German brand beers analyzed. Fibers (2 to 79 per liter), fragments (12 to 109) and granules (2 to 66) of plastic were traced. The level of contamination varied widely both among individual samples and among beers of the same brand but from different production batches.
Mineral water, no one is saved
A certain and direct source of microplastics is mineral water. In late 2017, a group of German researchers analyzed by the Raman method 38 different brands of mineral water packaged in 22 plastic Pet bottles including disposable and reusable, 9 glass and 3 cardboard. The result that microplastics were detected in all samples, with the highest level in reusable PET bottles, which contained up to 118 microparticles, compared to 14 detected in disposable bottles. In 80 percent of cases, these were fragments measuring between 5 and 20 micrometers. So small as to be undetectable by techniques adopted in similar previous studies.
Polyester (primary polyethylene terephthalate PET, 84 percent) and polypropylene (PP: 7 percent) were identified in the water contained in reusable plastic bottles. Exactly the materials from which the packaging is made, PET for bottles and PP for caps. Instead, only a few microparticles of PET, the plastic from which they are made, were found in the disposable ones.
Microplastic particles other than PET, such as polyethylene or polyolefins, have been found in the water of beverage cartons and even glass bottles. The research authors link its presence in cartons to polyethylene sheet coating and cap treatment. For glass, the origin of microparticles (up to 253 per liter) is to be clarified.
The scenario was confirmed by a further
study
German in early 2018. In the 32 samples of mineral water packaged in single-use and reusable plastic bottles and in glass bottles. All samples were found to be contaminated with microplastics, in the form of particles less than 5 micrometers in size. With strong suspicions that the source is packaging.
Other
study
conducted in the United States in early 2018 on 250 bottles of mineral water of 11 brands, purchased in different countries (including Italy), found the presence of plastic particles, including polypropylene (used to make the caps), nylon and polyethylene terephthalate (PET).
Marta Strinati
Notes
(1) The University of Southampton is famous in consumer circles for its studies on the occurrence of behavioral disorders in children accustomed to consuming foods containing azo dyes (later subject to label warnings and therefore replaced by the food industry with other dyes)
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".
