The invisible journey of pharmaceutical compounds from our bodies to natural ecosystems
Every year, thousands of tons of pharmaceuticals are produced and consumed worldwide. But what happens to these drugs once they've fulfilled their function in our bodies? The truth is that active pharmaceutical ingredients, or their metabolites, are excreted and embark on an invisible journey through wastewater to treatment plants, where they are not completely eliminated, and ultimately end up in the environment 1 .
This invisible journey constitutes a silent threat to ecosystems, as these chemical compounds can produce harmful effects on animals and plants, even at very low concentrations 1 .
Today we explore how scientific research has developed specific tools to assess the environmental behavior of these contaminants, combining both chemistry and information science knowledge to create comprehensive solutions for a complex problem .
When we consume a medication, its active ingredient doesn't magically disappear from our body. It's excreted unchanged or transformed into metabolites that, through wastewater, reach wastewater treatment plants (WWTPs) 1 . Research has shown that these plants only remove a portion of the pharmaceuticals, while the rest is released into the environment, incorporating into different environmental compartments: water, air, soil, sediments, and suspended solids .
The European Parliament has recognized this problem and requires an environmental risk assessment (ERA) for drug commercialization, allowing characterization of a substance's environmental risk .
To address this challenge, scientific research has developed prediction models based on the fugacity model described by Mackay in 1979 1 . These mathematical models simulate the behavior and distribution of chemical contaminants in different environmental compartments, becoming an essential tool for conducting more efficient and accurate environmental risk assessments.
The development of these models has two distinct dimensions: a purely chemical one, with all mathematical development, sensitivity evaluation, and validation with experimental data; and a documentary one, focused on the information search process, creation of resources for chemists, and development of computer applications that allow using the models in an accessible way .
Consumption
Excretion
Wastewater Treatment
Environmental Release
To validate the usefulness of the developed model, researchers applied it to the most consumed pharmaceuticals in Spain, following a rigorous methodology:
Identification of active ingredients with the highest consumption volume in Spain.
Using the fugacity model to calculate predicted concentrations of these drugs in different environmental compartments.
Contrasting model predictions with actual measured data in the environment.
Evaluating how variations in input parameters affected model results.
Determining possible harmful effects based on predicted concentrations 1 .
Application of the model revealed surprising data. Contrary to what might initially be thought, environmental concentrations of pharmaceuticals do not depend exclusively on consumption volume 1 . Some drugs like clarithromycin, clopidogrel, and sertraline, despite not being among the most consumed, are found in high concentrations in the environment .
| Pharmaceutical | Concentration near WWTPs (ng/L) | Concentration in remote waters (ng/L) |
|---|---|---|
| Paracetamol | >100 | <10 |
| Ibuprofen | >100 | <10 |
| Naproxen | >100 | <10 |
| Iopromide | >100 | <10 |
| Erythromycin | >100 | <10 |
| Diclofenac | >100 | <10 |
| Ranitidine | >100 | <10 |
Source: Adapted from Ribera and Fuentes (2011)
| Pharmaceutical | Consumption Level | Environmental Concentration |
|---|---|---|
| Clarithromycin | Moderate | High |
| Clopidogrel | Moderate | High |
| Sertraline | Moderate | High |
Source: Adapted from Ribera and Fuentes (2011)
The results demonstrated that some of the most consumed pharmaceuticals in Spain - paracetamol, ibuprofen, naproxen, iopromide, erythromycin, diclofenac and ranitidine - present concentrations above 100 ng/L in waters near WWTPs . These concentrations, although low in absolute terms, may be sufficient to produce harmful effects on aquatic organisms, especially when considering continuous exposure to mixtures of multiple pharmaceuticals.
The highest concentrations were obtained for estimated concentrations in local scope (PECLocal), measured a few kilometers downstream from emission sources like WWTPs .
The development of this environmental assessment tool required combining multiple resources and solutions, both from the chemical perspective and from the documentary perspective.
Allows simulation of the distribution and behavior of contaminants in different environmental compartments 1 .
Facilitate access to specialized information sources and promote efficient research .
Enables practical use of models for environmental risk assessment by industry 1 .
Provide essential data for calculations of expected concentrations in the environment .
Allow detection and quantification of very low concentrations (ng/L) of pharmaceuticals in environmental samples .
Evaluate how variations in input parameters affect model results and identify key variables .
The development of this tool for assessing the environmental behavior of chemical contaminants represents a significant advance in the fight against pharmaceutical pollution. The conclusions of this research suggest that the pharmaceutical industry could use the developed program to design drugs that are more environmentally benign, in accordance with current European directives .
Furthermore, the work highlights the close relationship between information science and any scientific research process . Tools for information search evolve rapidly, allowing more accurate and faster searches that improve communication within the scientific community. Staying informed about these advances is essential for any researcher .
Pharmaceutical pollution is a complex challenge that requires interdisciplinary solutions. The combination of sophisticated chemical models with efficient documentary tools represents a promising strategy for protecting our environment and preserving the health of aquatic and terrestrial ecosystems.
As a society, we need to become aware that every medicine we consume may have a second life in nature, and it is our responsibility to ensure that this second life does not become a threat to the planet.