Environmental effects of pharmaceutical substances | Umweltbundesamt

Having a reliable supply of pharmaceuticals is crucial for human and animal health. However, both this and the sometimes careless handling of pharmaceuticals are leading to increasing pollution of the environment with residues of active pharmaceutical ingredients, which are often persistent and can have undesirable effects on animals and plants. Therefore, the environmental discharge of pharmaceutical substances should be prevented or reduced as far as possible in order to protect ecosystems and drinking water resources in the long term.

Effects of pharmaceuticals in the environment

To assess the environmental risk of pharmaceutical substances, it is necessary to consider not only their consumption volumes and entry pathways but also their specific physicochemical properties, such as water and fat solubility, metabolism in the body, behaviour in the environment (e.g., degradation and mobility), and their ecotoxicity. Many of the properties that are important for the therapeutic effectiveness of medicines can be problematic from an environmental perspective, such as high stability or good water solubility.

Substances with so-called PBT properties are considered highly environmentally critical. These substances:

• degrade slowly and remain in the environment for a long time (persistent),
• Accumulate in organisms (bioaccumulative)
• Pose risks to humans and/or environmental organisms, and may be carcinogenic or disrupt the hormonal system (toxic)

Due to their properties, PBT substances should not enter the environment. They pose a risk regardless of concentration, and their long-term effects on humans and the environment are difficult to predict. This also applies to pharmaceutical substances with PBT properties, although very few active ingredients are known to fall into this category.

The concentrations of pharmaceutical substances measured in the environment are generally below the therapeutic doses used in medicinal products. However, this does not imply safety for the environment. Although pharmaceuticals are among the most thoroughly studied substances in terms of human toxicity, the ecotoxicological impacts of their relatively low but continuous presence in water bodies and soil remain largely unknown.

Download Table: German Environment Agency 2025: Toxicity of active substances to aquatic organisms - examples from aquatics with indication of the most sensitive species

Contraceptives cause reproductive disorders in aquatic organisms

Pharmaceutical substances containing hormones or hormone-like compounds are also problematic for the environment, as they are designed to intentionally interfere with the hormonal system as part of therapeutic treatments. These include contraceptives, hormone replacement therapies for menopause, treatments for hormone-dependent cancers, as well as medications for thyroid disorders and nervous system diseases. In industrial livestock farming, hormonal preparations are used, for example, to synchronise ovulation during artificial insemination.

These endocrine-active substances also enter the environment via wastewater. A prominent example is ethinylestradiol (EE2), a synthetic hormone used in oral contraceptives. Unlike the natural hormone estradiol, ethinylestradiol is much more stable, is poorly removed in sewage treatment plants, and therefore enters surface waters, where it is detected at very low concentrations (1). Research from laboratory and field studies indicates that endocrine-active substances in the environment can affect animal reproduction at concentrations as low as nanograms per litre, especially in fish and amphibians. Disruptions to the hormonal systems of animals can result in reduced testes size, decreased sperm mobility, or intersex development, all of which impair reproductive capability. A Canadian study demonstrated that long-term exposure to ethinylestradiol can even lead to population collapse in fish. This was observed in a multi-year field study on fathead minnows (Pimephales promelas), where severe feminisation of male fish hindered their ability to reproduce sufficiently, leading to a population decline (2). The tested concentrations ranged from 5 to 6 ng/L EE2, which are very low levels but can occur near sewage treatment plant effluents. The phenomenon of feminisation has also been observed in amphibians and reptiles.

Additionally, there are chemicals and pharmaceuticals that are not designed as hormones but can unintentionally disrupt the hormonal balance. These substances are known as endocrine disruptors (3).

Further information: Endocrine disruptors (in German)

The environmental assessment of hormonal preparations and other endocrine-active substances is particularly challenging due to the complexity of their effects and the low concentrations at which they occur in the environment. For many hormonally active substances, the effects are not immediately apparent. Reproductive toxicity, for example, often becomes evident only over a longer period and may need to be monitored across multiple generations.
Additionally, the analytical detection of these substances in environmental samples is difficult due to their low concentrations.

Vultures die from kidney failure due to diclofenac

One example of the environmental impact of pharmaceuticals is the mass die-off of several vulture species in the 1990s in Pakistan, India, and Bangladesh. Within a decade, the once large vulture populations were drastically reduced, bringing these birds to the brink of extinction. After years of investigation, the anti-inflammatory drug diclofenac was identified as the cause. Diclofenac has been widely used in veterinary medicine in India and Pakistan since the 1990s, particularly for cattle. The ingestion of diclofenac via the consumption of cattle carcasses led to fatal kidney failure in the vultures.

Further information:

• Pain relief gel - questions and answers
• Active Pharmaceutical Ingredients (API) - Diclofenac

Specific risks associated with antibiotics

In addition to other classes of active substances, antibiotic residues can also have negative environmental effects and thus impact entire ecosystems. Some macrolide antibiotics are known to harm cyanobacteria and algae at very low concentrations in the microgram per litre range (4), thereby disrupting entire food webs. Other antibiotics, such as sulfonamides and tetracyclines, can accumulate in soil (5; 6), where they exhibit toxic effects on soil organisms, potentially reducing soil fertility (7). Additionally, antibiotic residues are absorbed and accumulated by some plants, including crops (8). Apart from inhibiting plant growth, these residues can also enter the food chain. Beyond these direct environmental impacts, antibiotic residues pose a risk to humans, animals, and ecosystems by promoting the development and spread of antibiotic-resistant bacteria. According to the World Health Organization (WHO), such antibiotic-resistant pathogens are among the greatest global threats to health and food security. These resistant bacteria are no longer treatable with antibiotics, rendering even simple infections untreatable if antibiotics cease to be an effective therapy option. The spread of resistant bacteria is mainly due to the widespread use of antibiotics in intensive livestock farming and human medicine. To slow the development of new resistances and to preserve antibiotics as a sustainable therapy option for treating infectious diseases, several international and national initiatives have been launched. These include the "EU One Health Action Plan against AMR" and the "German Antibiotic Resistance Strategy (DART 2030)" (9; 10), which, in addition to resistance strategies, also include action plans for various fields of activity.

Further information: FAQ: Antibiotika und Antibiotikaresistenzen in der Umwelt (in German)

Contamination of drinking water and food

Traces of pharmaceuticals have been detected in drinking water, including the painkillers diclofenac, ibuprofen, and phenazone, as well as the antibiotic sulfamethoxazole and 17α-ethinylestradiol. These substances were found at concentrations of fractions of a microgram per litre, which are orders of magnitude below the therapeutically effective concentrations for humans. Specifically, the amounts detected per litre of drinking water are one hundred to one million times lower than the prescribed daily doses. Nevertheless, from a drinking water hygiene perspective and from the consumer's viewpoint, even these low concentrations in drinking water are undesirable (11; 12). Traces of active substances—even if proven to be harmless—contradict the ideal of pure drinking water, which states that drinking water should be free from foreign substances. This also conflicts with the minimisation principle, which aims to keep contaminants as low as reasonably achievable. Although long-term risks cannot yet be scientifically determined, precautionary measures and continued monitoring are necessary in light of the projected increase in pharmaceutical demand.

References

1. SCHEER (Scientific Committee on Health, Environmental and Emerging Risks), Preliminary Opinion on "Draft Environmental Quality Standards for Priority Substances under the Water Framework Directive", 17-alpha-ethinylestradiol (EE2), Beta-Estradiol (E2) and Estrone (E1), 1st March 2022
2. Kidd, K.A., P.J. Blanchfield, K.H. Mills, V.P. Palace, R.E. Evans, J.M. Lazorchak and R.W. Flick: Collapse of a fish population after exposure to a synthetic estrogen. Proceedings of the National Academy of Sciences of the United States of America, 2007. 104(21): p. 8897-8901.
3. Bergman Å.: State of the science of endocrine disrupting chemicals 2012 :summary for decision makers. UNEP, WHO 2013. 
4. Liu F, Ying GG, Tao R, Zhao JL, Yang JF, Zhao LF. Effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities. Environ Pollut 2009; 157: 1636–1642 
5. Hamscher, G., Sczesny, S., Höper, H., & Nau, H. (2002). Determination of persistent tetracycline residues in soil fertilized with liquid manure by high-performance liquid chromatography with electrospray ionization tandem mass spectrometry. Analytical chemistry, 74(7), 1509-1518. 
6. Walters, E., McClellan, K., & Halden, R. U. (2010). Occurrence and loss over three years of 72 pharmaceuticals and personal care products from biosolids–soil mixtures in outdoor esocosms. Water research, 44(20), 6011-6020. 
7. Grenni P, Ancona V, Caracciolo AB. Ecological effects of antibiotics on natural ecosystems: A review. Microchemical Journal 2018; 136: 25–398.
8. Lillenberg M, Yurchenko S, Kipper K, Herodes K, Pihl V, Lõhmus R, et al. Presence of fluoroquinolones and sulfonamides in urban sewage sludge and their degradation as a result of composting. International Journal of Environmant Science & Technology 2010; 7: 307–312.
9. EC - European Commission. A European One Health Action Plan against Antimicrobial Resistance (AMR). Luxemburg: Publications Office of the EU; 2017. p. 24.
10. BMG - Bundesministerium für Gesundheit 2024, DART 2030 - Deutsche Antibiotika-Resistenzstrategie,
11. Umweltbundesamt 2020: Die UBA-Datenbank „Arzneimittel in der Umwelt“
12. Dieter H, Götz, K, Kümmerer K, Keil F (2010): Handlungsmöglichkeiten zur Minderung des Eintrags von Humanarzneimitteln und ihren Rückständen in das Roh- und Trinkwasser.