Greater knowledge of emerging pollutants and their effects is needed to establish criteria for action.
There are a number of potentially polluting compounds that are not monitored on a regular basis and for which there is no standardized or reviewed data on their impact on human health and ecosystems; these are known as emerging pollutants. Research and innovation in the environmental field is constant and this allows substances that had not been controlled until now to be monitored and regulated or to be revised according to scientific advances.
One such case is that of pharmaceuticals. For most of the non-standard pharmaceutical products present in the global market, there are no assessments of their presence, dispersion mechanisms or environmental impacts, although many international studies already state that the levels of pharmaceuticals detected in surface waters are worrying. This fact could be associated with the increase in the consumption of drugs in recent decades, especially in Western societies.
The particular design characteristics of pharmaceutical products, many of which are intended to be stable enough to interact with target molecules and achieve effects at low doses, can lead to undesirable effects on the environment.
Our bodies metabolize only a portion of the drugs or active ingredients we consume. The rest, as well as other metabolites, which may be active or inactive and can potentially be transformed into numerous other compounds, are excreted by us and end up in drains, reach sewage treatment plants or are dispersed in the environment.
But drug ingestion is not the only problem. The improper disposal of expired drugs that are flushed down toilets and sinks also contributes to this “pharmaceutical contamination”.
Impact on human health
According to the European Environmental Agency, there is evidence of adverse effects on human health from exposure to the drugs, including thyroid disease, increased cholesterol levels, liver damage, kidney cancer, testicular cancer and developmental problems in fetuses. However, detailed studies on the risk of chronic exposure to low levels of drugs are lacking.
The scientific journal PNAS(The Proceedings of the National Academy of Sciences) published in 2022 an article titled Pharmaceutical contamination of the world’s rivers in which scientists from several countries have participated to collect and analyze samples from more than 200 rivers, from the Amazon to the Manzanares. Twenty-five percent of the samples analyzed in this study contained at least one of the 61 drugs sought.
The highest concentrations of these compounds were found in rivers in South Asia, South America and sub-Saharan Africa, especially in poor countries with poor wastewater treatment or drug factories.
In the Manzanares River, an average of 17 of drugs has been detected, with peaks of almost 60
as it approaches the municipality of Rivas Vaciamadrid, making it the most drug-polluted river in Europe, partly due to its low flow, which reduces its capacity to dilute the pollution.
These data indicate that pharmaceuticals are a global threat to the environment and human health and their presence in waters and their effects need to be investigated and monitored.
Regulation
In terms of regulation on the presence of these compounds, in Europe the Drinking Water Directive 98/83/EC sets quality standards for drinking water to ensure its wholesomeness and cleanliness. The original Directive included the regular monitoring and analysis of 48 microbiological and chemical parameters and other indicators; in the new version, bisphenol A, pharmaceuticals and PFAS, among others, are added to the list of compounds.
(Litoclean scheme)
The fact that there are not enough studies and knowledge about emerging contaminants means that they are not monitored and that, for example, conventional wastewater treatment plants (WWTPs) do not eliminate them, since they were designed to eliminate organic matter and pathogens, but not this type of compound, which, moreover, are generally present in low concentrations.
The widespread presence of pharmaceuticals in rivers and WWTP effluents is a challenge for the scientific and environmental communities and for the authorities that must ensure water safety. It requires joint work by all parties involved in order to define the mixtures of compounds to be analyzed, to know their toxicological properties individually or in a complex mixture, and to have laboratories that demonstrate robustness in their detection, as well as regulatory bodies that can apply harmonized criteria.
There is an enormous field of development to know, understand, measure and contain this contamination, from the application of new sensing technologies to early alerts of drug levels in WWTPs or rivers, among others.
The great challenge in the environmental sector today is to be in continuous learning, since regulations, production techniques, the development of new substances and even their interactions are constantly evolving. In this scenario, it is necessary to have the knowledge of a multidisciplinary group of professionals who generate ideas to solve each project. There are probably no magic or unique solutions, but results are expected to be achieved by combining different alternatives and technologies to contain this problem.
