In 2014, a team of researchers from the University of the Basque Country discovered signs of ‘feminization’ in the mubles or corcones (Mugil cephalus), a species of marine fish that inhabit various estuaries off the Basque coasts. This unusual sex change appeared to be due to a group of chemical pollutants called endocrine disruptors, which come from widely used products: pesticides, detergents, and even birth control pills.
The case of ‘transsexual’ fish was very popular, but it was only one of the many studies that in recent years have been devoted to analyzing the presence and effects of chemical pollutants in the waters of rivers and seas. And these substances do not come exclusively from industrial and agricultural activities: there is a fraction of the drugs that we take that our body is not able to absorb and that we evacuate with urine. After passing through the treatment plants, which are not able to eliminate them completely, these compounds end up keeping fish like the furniture from the Basque Country company: ibuprofen, salicylic acid and other medicines for daily use are already a constant in our waters.
Are they dangerous for ecosystems and for human health?
A general answer cannot be given, since we are talking about a great variety of compounds with very different properties: some dissolve more easily in water and disappear soon, others have a great capacity to bioaccumulate, some will be harmless, others will not ... Damià Barceló, scientist at the Catalan Institute for Water Research and an expert in this field, one of the drugs that should concern us most is diclofenac. Its name may not sound familiar to you, but we are talking about the famous Voltarén, which is sold in pharmacies without a prescription and is very commonly used to treat muscle pain and rheumatism.
Its massive use in veterinary medicine has already wreaked havoc among several populations of vultures in Asia, and could be behind the death of 6,000 griffon vultures in Spain, according to a work published in early 2016 in the Journal of Applied Ecology. The Barceló team has searched for diclofenac in the waters of four Mediterranean rivers, verifying its presence in various species of fish that inhabit them. As explained by the researcher, it seems that the European Union plans to include this drug in its Framework Directive, which will force treatment plants to eliminate it completely.
Antibiotics in the Mar Menor
The effects of medicines on water are also very different depending on the ecosystem they reach, and some are more vulnerable than others to contamination. For example, the Mar Menor, sadly a star in the news last summer: as a result of many years of uncontrolled discharges, the waters of this natural jewel are more murky than ever. "The shallow nature and the limited capacity for renewal of the waters of the Mar Menor make this coastal lagoon more vulnerable to the load of pollutants than other open coastal spaces", explains Víctor León, researcher at the Oceanographic Center of Murcia, whose team he has just published a work in which he analyzes the presence of drugs in the Mar Menor.
Interestingly, the concentrations of the different compounds studied varied depending on the season of the year: in summer, when there is a greater influx of tourists in the area, the predominant drugs were those used for psychiatric treatments, as well as drugs for high blood pressure and diuretics. Furthermore, antibiotics were, as a whole, the group of compounds with the greatest presence in the lagoon. "It is necessary to indicate that these data are from 2010, and until two years ago the effluents from the Los Alcázares wastewater treatment plant were discharged, with the burden of drugs that it supposes since many of these compounds are not efficiently eliminated in these plants ", says the researcher. "Fortunately, the situation has changed since this water is now reused for agricultural irrigation, so this direct discharge has ceased. However, other sources associated with urban centers have been detected, probably due to uncontrolled discharges and the presence of bathers during the summer season ".
How long do drugs stay in water?
Given these data on the presence of drugs in the water, perhaps one might think that the best thing one can do when faced with a headache is to take a bath in the nearest river or beach, but the reality is, obviously, quite different. As we have already mentioned, many drugs degrade rapidly in water: "The Oceanography and Littoral Contamination team of the University of Cádiz has characterized biodegradation in seawater, showing a rate higher than 80% in most cases after 28 days. In addition, in this same study they confirmed that photodegradation was a much faster process and that it eliminated more than 90% in 24 hours for most of the drugs studied ", explains León.
Furthermore, each organism can respond in a different way to the presence of pollutants: "Macroinvertebrates and algae are the groups most affected," says Barceló. "Antibiotics influence the biofilm of rivers, made up of algae and bacteria. In addition, beta-blockers and anti-inflammatories affect certain macroinvertebrates such as chironomids."
In the Mar Menor, the team from the Murcia Oceanographic Center characterized the accumulation of some drugs in bivalves - cockle, oyster and nacra - and in fish - galupe and fox - during the spring and autumn of 2010. The results have just been published in the Environmental Research magazine. "The concentrations observed were generally low, but the highest presence of compounds was detected in galupe muscle (Liza aurata), probably associated with the eating habits of this group of fish, which frequent the vicinity of the dumping points or areas where human activities are concentrated, "explains León.
With regard to the effects that these compounds can cause in organisms, the researcher tells us that it would be necessary to carry out tests in controlled laboratory conditions, as other research groups are doing in some marine species. "At the moment data are only available for a small group of drugs and species, so a diagnosis can not yet be made on the species that may be more sensitive," says the scientist. "What can be pointed out is that the mooges - a family of fish to which the galupe belongs - are a group that should be considered as a possible indicator for the study of the impact of drugs in coastal areas, if they are confirmed in other areas. results obtained in the Mar Menor ". This means that, by analyzing the presence of drugs in these fish, we could obtain a good diagnosis of the global situation of pollutants in the analyzed ecosystem.
How to prevent drugs from reaching rivers and seas?
For Barceló, it is possible to technically improve the capacity of the wastewater treatment plants. "Technologies such as membrane bioreactors or nanofiltration have been seen to remove large amounts of drugs and other emerging contaminants, but that obviously requires additional investment," he says. An investment that, unfortunately, in many cases does not arrive until a regulation such as the European Union's Water Framework Directive requires it.
But there are also measures that citizens can take at the individual level. In the first place, exercise a responsible consumption of medicines. It's not about waiting to die of pain before taking ibuprofen, but you don't have to jump in at the slightest discomfort either. In addition, avoiding drug abuse is not only good for the environment: we also give our liver a break.
Finally, there is a very widespread practice - as well as harmful - that consists of flushing expired medicines down the sink or toilet. However, the most correct action when putting order in our medicine cabinet is to deposit the waste at a SIGRE point, which we can already find in more than 20,000 pharmacies throughout the Spanish geography. They are responsible for separating its components for subsequent recycling, and most of the non-hazardous drugs are used to produce energy through a process called recovery. A destination, without a doubt, much more worthy than ending up floating through the water in the company of fish and bathers.