MRI contrast agent detected in cola

The study finds gadolinium in fast-food drinks of all German cities examined

Because coke and other drinks are mixed with tap water in fast food restaurants, they are contaminated with the rare earth element gadolinium - and probably other drug residues as well. © artisteer / iStock
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Not tasty: In many German cities are residues of the contrast medium gadolinium in the coke of fast food chains, as tests prove. The gadolinium gets into the drinks because they are prepared as a syrup with tap water. The proven quantities are not harmful to health, but indicate that presumably other drug residues reach the drinking water in drinks and food, as the researchers report.

The rare earth metal gadolinium is frequently used in medicine as a contrast agent in magnetic resonance imaging (MRI). Because it is bound to a carrier, it can not be absorbed by the body, so they thought so far. However, studies have since proven that at least part of the gadolinium remains in the brain after contrast media use - with as yet unexplained consequences. It is clear, however, that the gadolinium gets into larger rivers in rivers and also the drinking water via wastewater.

Tests in six German cities

But that's not all, as Katja Schmidt and her colleagues at Jacoby University Bremen have discovered. For their study, they had investigated whether gadolinium and other residues can reach the drinking water in the drink. Fast food chains such as McDonalds and Burger King are supplied with cola and other sodas as syrups, which they prepare with tap water and CO2 to make the finished drink.

For their tests, the researchers have taken cola and drinking water samples from branches of both fast-food chains in the German cities of Berlin, Dusseldorf, Essen, Karlsruhe, Munich and Dresden. They then analyzed them for the content of gadolinium and additionally used a method to determine the proportion of this rare earth metal derived from human sources.

Gadolinium in cola - everywhere

The result: "We have found anthropogenic gadolinium in drinking water as well as in soft drinks in all cities examined, " report Schmidt and her colleagues. This confirms that the contrast agent residues are not completely removed from the water either in wastewater treatment or in drinking water treatment. display

In addition, the analyzes show how easily the gadolinium and other residues get into the drinking water via the drinking water. In the coke of fast food restaurants, gadolinium levels were similar to tap water. "Although the restaurants state that this tap water is additionally cleaned beforehand, this cleaning step is obviously not able to remove the contrast medium residues, " says Schmidt's colleague Michael Bau.

Contamination in Berlin and D sseldorf the highest

The additional analyzes confirmed that this gadolinium is not of natural origin but originates from man-made residues: "In Berlin and D sseldorf, where tap water originates mainly from bank filtrate, 85 to 99 percent of gadolinium comes from human sources, "the researchers report. The contrast agent residues reach the drinking water via the polluted river water and from there into the cola.

But also in the other cities studied, part of the gadolinium in drinking water comes from MRI contrast media: 31 percent in Bremen, 34 percent in Karlsruhe, 63 percent in Dresden and 91 percent in Munich. The relatively high level of residue in Munich was also unexpected for the researchers: "The surprisingly high proportion of anthropogenic gadolinium in Munich tap water reveals that even the shallow groundwater in the two alpine exploiters are already exposed to anthropogenic contamination ", the scientists say.

Probably not harmful to health

What is the consequence? As the researchers emphasize, according to the current state of knowledge, the now proven gadolinium concentrations are not detrimental to health. However, they suggest that in addition to the rare earth metal, other chemicals and drug residues will most likely end up in drinking water and beverages. For example, studies have shown evidence of low blood sugar levels, antibiotics, and antidepressants in waters, for example.

"These are in particular the so-called endocrine disruptors, which have hormone-like effects in humans and animals and in contrast to the contrast agent gadolinium affect health even in very low concentrations, " explains Bau. Gadolinium is an indicator that many of these substances are now entering our food chain via drinking water. (Science of the Total Environment, 2019; doi: 10.1016 / j.scitotenv.2019.07.075)

Source: Jacobs University Bremen

- Nadja Podbregar