Pharmaceutical residues in drinking water cannot be sufficiently filtered by the normal water treatment in the sewage plant. What are the consequences? We explain what companies and consumers can do.
WASTEWATER TREATMENT: HOW IS THE WATER PURIFIED?
Conventional wastewater treatment plants cannot filter out pharmaceutical residues properly. In the second stage, the mainly mechanically pre-treated wastewater is purified with the help of micro-organisms, i.e. bacteria. In this process, mainly organic substances are broken down, for example from food residues and faeces.
In more advanced wastewater treatment, other substances such as phosphates and heavy metals are precipitated and flocculated with chemicals and removed from the water. What remains is a bulky sludge, which has to be stabilized. The solid residue is used for agricultural purposes, deposited in landfills or incinerated.
How drug degradation occurs and which degradation products are formed has only been clarified in individual cases. It is likely that during oxidative biological degradation, drugs are not only converted to carbon dioxide and bacterial mass. Degradation products are probably also formed, which can no longer be detected with current analytical methods.
Dr. Manfred Hilp, a pharmacist and graduate chemist, writes in the pharmaceutical journal that ibuprofen, for example, shows “bad environmental behavior”. It was detected in drinking water, whereas in the case of acetylsalicylic acid (ASS), salicylic acid was only found in trace amounts in running water, despite considerably higher consumption.
The analgesic paracetamol is also considered fairly degradable. Diclofenac, on the other hand, is a concern because it harms birds and fish. Hormonal residues from the birth control pill can affect the reproduction of animals.
MODERN METHODS REQUIRED
Scientists and the Federal Environment Agency are calling for the complete elimination of pharmaceutical and other chemical residues from wastewater. To achieve this, wastewater treatment should be technologically upgraded in a fourth purification step, e.g. nano- or microfiltration or activated carbon processes are requested: chemical micropollutants could be efficiently filtered out of wastewater by ozone oxidation or adsorption on activated carbon filters.
PHARMACEUTICAL COMPANIES AND CONSUMERS ARE ALSO IN DEMAND
However, scientific and environmental authorities are not only asking for an additional treatment step. It is also important that as few drugs as possible end up in wastewater. For example, pharmaceutical companies could disclose environmental data on new drugs during the approval process.
Consumers should also dispose of their medications in residual waste rather than down the sink or toilet. Expired or no longer needed medications can also be returned to the pharmacy for disposal.
NO HARMFUL EFFECTS ON HUMAN HEALTH
There is still no reason to do without tap water. But as life expectancy increases and more and more drugs are available without a prescription, the amount of drugs taken, and later excreted, will also increase.
There is certainly a need for action in the area of filtration of pharmaceutical residues in water, but the concentrations of pharmaceutical residues detected in water are very low and, according to current knowledge, harmless to humans. Furthermore, the findings of drug residues in drinking water are the exception; an effect of these extremely low concentrations is not detectable, as they are far below therapeutic doses.