Umweltbundesamt
Click to enlargeResidues of human medicines primarily enter the environment through household wastewater.
Residues of human medicinal products for human use enter the environment primarily through wastewater. Pharmaceutical substances are highly biologically active and can have harmful effects on living organisms, particularly in aquatic environments.
Medicines are essential tools in medical practice and are omnipresent in our daily lives. We all take medications as needed or on a regular basis, and our consumption of medicinal products generally increases with age. On average, people aged 85 to 89 take 23 times the amount of medications compared to those aged 20 to 24 (1). Due to the growing proportion of older population groups, an increase in medication consumption is expected in Germany over the coming decades (2).
In Germany, approximately 2,500 different pharmaceutical substances (3) are available in over 100,000 human medicinal products (4), with annual consumption exceeding 35,000 tonnes (3). In 2021, medications were most frequently prescribed for the following conditions (5):
Human pharmaceuticals are excreted by the human body in a changed (metabolized) and, in some cases, unchanged form. They enter wastewater through excretion as well as by being washed off the skin after topical application, eventually reaching sewage treatment plants. Improper disposal of unused medicines via sinks and toilets also contributes to this issue.
Further information: Environmentally friendly disposal of leftover drugs
Sewage treatment plants cannot filter out all pharmaceutical substances present in wastewater. The treated water often still contains pharmaceutical substance residues, which are then discharged into water bodies with the effluent from the treatment plants. As a result, many tonnes of pharmaceutical substances and their metabolites enter the environment each year via sewage treatment plants. Some substances remain in sewage sludge.
In 2022, around 80% of sewage sludge in Germany was co-incinerated in waste incineration plants, effectively destroying the pharmaceutical substances. However, even in 2024, sewage sludge is still used as agricultural fertiliser, allowing pharmaceuticals from human medicinal products to enter the environment through this pathway as well (6).
Contaminated industrial wastewater from pharmaceutical production is another source of pollution. Veterinary medicines also enter the environment, primarily through fertiliser in the form of slurry and manure from medicated animals, which is spread on agricultural fields.
The main route of entry of human pharmaceuticals into the environment is via wastewater.
By 2020, 992 pharmaceutical substances and their degradation products above the detection limit had been measured in 89 countries worldwide in soils, surface waters, and sediments — 221 more substances than in 2016. In Germany, 414 pharmaceutical substances, including their degradation products, were found in the environment, an increase of 145 compared to 2016 (7).
Substances from the following classes of pharmaceuticals are detected with particular frequency:
Pharmaceuticals are regularly measured as part of water monitoring conducted by the German Federal States and are found almost ubiquitously and throughout the year in surface waters, as well as in soil and groundwater samples. Traces of pharmaceuticals have also been detected in drinking water in isolated cases. Particularly high concentrations of human pharmaceuticals are measured in the effluents of sewage treatment plants. Consequently, surface waters with a high proportion of treated wastewater from municipal sewage treatment plants also contain higher levels of pharmaceutical substances.
Further information: Entry, occurrence, and effects of pharmaceuticals in the environment
Pharmaceutical substances are highly biologically active compounds that are specifically designed to interfere with the regulatory mechanisms of organisms. They can, for example, influence metabolism, disrupt hormonal balance, or alter cell-to-cell signal transmission. Due to their biological activity and wide range of specific effects, pharmaceuticals also impact other living organisms when they enter the environment.
For many pharmaceuticals, the extent of the risks is difficult to assess, mainly due to a lack of data on their effects and the absence of long-term studies. This is concerning, as harmful effects on environmental organisms have already been clearly demonstrated for some pharmaceuticals.
For instance, the synthetic hormonal substance in contraceptive pills (17α-ethinylestradiol) affects the reproductive capacity of fish and amphibians even at very low concentrations. Disruptions to the animals' hormonal systems may manifest as smaller testes, reduced sperm mobility, or the development of intersex characteristics. Another example is the painkiller diclofenac, which damages internal organs such as the liver and kidneys in fish.
Further information:
Some antibiotics (e. g. macrolides) harm cyanobacteria and algae (8), endangering entire food systems. Other antibiotic substances (e. g. sulfonamides and tetracyclines) negatively affect soil organisms, potentially reducing soil fertility (9).
In addition to their direct negative environmental effects, antibiotic substances also pose a risk by promoting the development and spread of antibiotic-resistant bacteria. According to the World Health Organisation (WHO), resistant pathogens are one of the greatest global health threats, as bacteria that have developed resistance can no longer be treated with antibiotics. If antibiotics become ineffective, even simple infections may no longer be treatable. The widespread use of antibiotics in intensive livestock farming and human medicine is a major driver of the spread of resistant bacteria.
Antibiotic resistance in bacteria that cause infections in humans — so-called human pathogens — is a serious public health concern. Multi-resistant microorganisms have also repeatedly been detected in the environment, for example in rivers and streams downstream of sewage treatment plant effluents, which often contain particularly high concentrations of antibiotics. Although Germany introduced the German Antibiotic Resistance Strategy (DART) in 2008 as a national and international framework for combating antimicrobial resistance, there is still significant research needed regarding resistance in the environment.
Pharmaceutical substances are highly biologically active and can have harmful effects on living organisms in the environment.
Water requires special protection, as it is not only a vital habitat for aquatic organisms but also an essential resource for human life. Nevertheless, individual studies have detected traces of pharmaceuticals in drinking water, including the painkillers diclofenac, ibuprofen, and phenazone, as well as the antibiotic sulfamethoxazole and the contraceptive substance 17α-ethinylestradiol (7). The detected concentrations are between one hundred and one million times lower than the required daily doses and thus below therapeutically effective levels for humans. Based on current knowledge, no adverse effects on human health are expected.
However, in line with the precautionary principle, efforts should be made to reduce the entry of pharmaceutical substances into the environment, especially as the long-term effects of continuous exposure to even low concentrations on humans and ecosystems remain unknown. Moreover, the presence of pharmaceutical residues — regardless of whether they are proven to be harmful — contradicts the ideal of pure drinking water, which stipulates that drinking water should be free from contaminating substances. It also conflicts with the minimization principle, i.e. the requirement to keep contamination as low as possible with reasonable effort.
Even though long-term risks cannot yet be scientifically determined, precautionary measures and continued monitoring are essential in light of the predicted increase in pharmaceutical consumption.
Further information:
Antibiotic residues can be absorbed and accumulated by certain plants, including crops (10). In addition to inhibiting plant growth, these residues can also enter the food chain.
Antibiotics also affect the composition of microbial communities in soils, potentially harming beneficial fungi such as mycorrhiza. If antibiotics impact microorganisms involved in the nitrogen cycle, soil fertility may be negatively affected (11), or nitrate breakdown could be inhibited, leading to increased water pollution (12).
There is a fundamental risk that pharmaceuticals or resistant microorganisms could enter the human food chain via food products. Overall knowledge on this issue remains incomplete., however,the accumulation of pharmaceutical substances in both plant-based and animal-derived foods has already been demonstrated. Field studies have shown that veterinary pharmaceuticals can be transferred through the manure-soil-plant pathway, even when using dosages commonly applied in veterinary practice. For example, pharmaceuticals have been detected in cereal crops such as winter wheat, including in the harvested grain itself.
Pharmaceutical substances in water bodies have undesirable effects on animals and plants. If pharmaceutical residues enter groundwater, it makes the extraction of drinking water more difficult.
The UBA’s motto, For our environment (“Für Mensch und Umwelt”), sums up our mission pretty well, we feel. In this video we give an insight into our work.
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