Pharmaceutical Residues in Drinking Water

Pharmaceuticals are indispensible to human as well as to animal health. Yet their ecological impact gives cause for concern. Many pharmaceuticals are persistent, which means they are degraded only slowly and accumulate in the environment. In higher concentrations these residues may be toxic for aquatic organisms. Since 1974 the German Environmental Agency (UBA) has been compiling an environmental research database (UFORDAT) which comprises monitoring data on pharmaceutical residues in the environment. Similarly, regional water suppliers regularly have their drinking water tested for pharmaceutical residues and publish the data.

Detection of pharmaceuticals in drinking water by the ifp residues Lab

We test for pharmaceutical residues in water by means of HPLC-MS/MS. The range of substances comprises the most frequently used human and veterinary pharmaceuticals, including their relevant metabolites:

  • Analgetics and antiphlogistics, e.g. Diclofenac, Ibuprofen
  • Antibiotics, e.g. Chloramphenicol, Sulfamethoxazol
  • Anticonvulsants, e.g. Phenobarbital, Primidon
  • Antilipidemics, e.g. Bezafibrat, Fenofibrat
  • Beta blockers, e.g. Metoprolol, Propranolol
  • Gestagens, e.g. Norethisteron
  • Contrast agents, e.g. Amidotrizoesäure, Gadolinium (by means of ICP-MS)
  • Psychoactive drugs, e.g. Diazepam, Oxazepam
  • Cytostatics, e.g. Cyclophosphamid
  • Veterinary pharmaceuticals, e.g. Sulfamethoxin, Tiamulin (antibiotics), Ivermectin (antiparasitics)

Human pharmaceuticals get into the water via faeces and incorrect disposal

Human pharmaceuticals and their metabolites get into the municipal wastewater mainly via human excretion. A further source not to be underestimated is incorrect disposal of pharmaceuticals, e.g. in the toilet or domestic waste that is not burnt. Since the technologies used in municipal sewage plants do not suffice to entirely remove pharmaceutical residues, these substances enter flowing waters and the drinking water together with the cleaned water. Pharmaceuticals are highly mobile thanks to their mostly polar structure. This allows them to get into the groundwater through leaks in the wastewater system or as a result of surface water seepage.

Veterinary pharmaceuticals in groundwater: the result of intensive agriculture

Veterinary drug residues result from the intensive use of medication in industrial livestock farming as found in conventional agriculture. The substances and metabolites that are then excreted by the animals get into farm fertilizer which is used to treat the soil and arable land. From there the substances seep into the soil and into the groundwater. Surface waters may also be polluted by surface runoff after heavy rainfalls.

Risk assessment of pharmaceutical residues in drinking water

In Germany, risk assessment of pharmaceutical residues in drinking water is done by the Federal Environmental Agency (UBA) based on toxicological data. For non-genotoxic compounds, the Agency recommends a general target value (precautionary value) of max. 0.1 µg/L per individual substance in order to minimize consumer risk. Up to this concentration health assessment is not necessary, since no risk is expected for any of the age groups including infants and toddlers. The Federal Environmental Agency specifies health orientation values, guideline values and intervention values, which are used to evaluate the health risk of pharmaceutical residues in drinking water. If these health orientation values and the guideline values are not exceeded, the drinking water is declared safe for human consumption. If intervention values are reached or even exceeded, the drinking water is no longer classified as safe for consumption. In this case the origin of pharmaceutical entry should be investigated and its concentration minimized as far as possible.