Gadolinium is used in contrast media in MRT examinations and enters the sewage system via the patient’s urine. The result: river water and thus drinking water obtained from rivers or bank filtrate are contaminated with gadolinium.
The stable substances also include gadolinium complexes, which are used as contrast media in magnetic resonance tomography (MRT). Due to their high stability, they are not changed by the human body and get into the sewage system via the patients urine. Conventional sewage treatment plants are not designed to remove these substances from the water and so they reach rivers and lakes. As the number of people who are examined with an MRT increases, so too do the levels of gadolinium in water bodies. Since most patients are now diagnosed only on an outpatient basis, they excrete the administered gadolinium complexes at home. Therefore, even in rural areas, there are increased gadolinium concentrations in surface water and groundwater.
The gadolinium concentration in water can be used to understand natural processes like the seepage of rivers into the groundwater and can be used to delimit surface water from groundwater and to calculate proportions. This also provides information on how high the proportion of treated wastewater is in the drinking water. This is particularly important for water suppliers who do not get their water from alpine springs but groundwater resources.
Is there a solution?
So far there are no solutions to remove gadolinium complexes from sewage water on an industrial scale. The water suppliers are faced with a problem that they neither caused nor can solve on their own. As long as there is no collection and gadolinium extraction from the collected urine the problem might not be solved.
Measured concentrations are not hazardous to health
The current state of knowledge says the measured concentrations are not harmful to health, but still, it is an indicator of wastewater presence in the drinking water. As the quantities of contrast media used are increasing from year to year it could however get a problem soon. Now it is up to the experts to find a solution.
Of course, gadolinium is not the only one of the so-called emerging contaminants that are increasingly enriching in our environment. It will be important to monitor them closely in the future, as the effects on humans and the environment are still unknown.