In our daily lives, we use a wide variety of products that, without knowing it, leave an invisible mark on the environment. Medicines, cosmetics, plastics, cleaning products, and even pesticide residues, when discarded or eliminated by the body, end up reaching bodies of water through drainage, agriculture, or industry. These chemical compounds are known as "emerging pollutants."
In recent decades, the growing presence of emerging pollutants in water resources has raised alarms among the scientific community and public health organizations around the world.
On one hand, the consequences of these compounds are not yet fully addressed by environmental laws. On the other hand, a concerning aspect of the issue is that traditional water treatment systems are not designed to completely remove them, which allows their accumulation in rivers, lakes, aquifers, and even in drinking water, thus creating a growing risk to human health and aquatic ecosystems.
The biological effects of emerging pollutants can be significant, especially when they act as endocrine disruptors, that is, substances that interfere with the hormonal system of living beings. Prolonged exposure to these compounds has been linked to serious effects in both humans and animals.
A global presence, a local challenge
At the international level, multiple studies have detected increasing amounts of emerging pollutants in rivers, lakes, aquifers, and even in drinking water. In Mexico, recent research reveals the presence of substances such as diclofenac, carbamazepine, sulfamethoxazole, Bisphenol A, nonylphenols, as well as various antibiotics in both surface and groundwater.
In a study in the Mezquital Valley —an area of artificial recharge with wastewater from Mexico City— up to 23 active pharmaceuticals were detected in groundwater. Additionally, a recent analysis identified that in bodies of water such as the Xochimilco canals and the Apatlaco River in Cuernavaca, international limits for pollutants such as triclosan, Bisphenol A, and the synthetic estrogen EE2 or ethinylestradiol were greatly exceeded. This estrogen is found in contraceptive pills and reaches the water through urine and wastewater.
A study conducted in Delhi, India, found surprisingly high levels of diclofenac —a common painkiller— in groundwater, reaching up to 1.3 milligrams per liter. This reveals how serious the problem of pharmaceutical pollution can be: what is concerning is that groundwater has less oxidative capacity, so it takes longer to break down these types of compounds compared to river or lake water.
Effects on human health and ecosystems
One of the most troubling aspects of these compounds is their ability to alter biological activity, even at extremely low concentrations, often at levels of nanograms per liter. Small amounts of endocrine disruptors such as Bisphenol A, phthalates, or synthetic hormones can disrupt the hormonal balance in both humans and aquatic wildlife. Cases have been documented of hormonal changes in marine fauna exposed to urban effluents, as well as decreases in fertility and alterations in the reproductive behavior of amphibians.
On the human level, there is evidence that prolonged exposure to these substances is associated with neurological, immunological, and reproductive problems, some examples include:
For example, Bisphenol A or BPA, found in plastics and can linings, has been associated with alterations in fetal development, thyroid dysfunction, metabolic disorders such as obesity, and even an increased risk of breast and prostate cancer. Regarding neurological effects, BPA has been linked to behavioral disorders such as anxiety, impulsivity, and lack of concentration and attention.
Parabens, commonly used as preservatives in cosmetic and personal care products due to their antimicrobial properties, mimic estrogen, which can disrupt the hormonal system. Their presence in breast tumor tissues has raised concern about their possible link to breast cancer. These substances could be related to increased susceptibility to infections and the development of autoimmune diseases.
Microplastics, particles smaller than 5 mm generated by the massive use of plastics in our daily lives and their fragmentation, contaminate our environment. These enter the human body mainly through the ingestion of contaminated food and water, as well as by inhaling particles in the air. According to a review, Latin America faces a high risk due to the lack of adequate wastewater treatment infrastructure and the growing presence of microplastics in aquatic ecosystems.
Recent studies have detected microplastics in human blood, breast milk, and even in placentas, suggesting that these particles are penetrating fundamental physiological barriers. Although their direct effect on health is still under investigation, it is known that they can act as carriers of chemical contaminants such as heavy metals or endocrine disruptors adhered to their surface. Furthermore, upon entering the body, they can induce inflammation, oxidative stress, and cellular damage—effects that could contribute to cardiovascular, gastrointestinal diseases, or even long-term carcinogenic processes.
Many of these substances reach rivers and aquifers through wastewater, where they remain active. This environment favors the emergence of resistant bacteria that learn to survive current treatments. The implications of this phenomenon are alarming, as the spread of resistant bacteria not only compromises the effectiveness of antibiotics in treating human and animal infections, but also puts public health and food security at risk, increasing the possibility of outbreaks of resistant infections and complicating prevention and treatment strategies.
According to the World Health Organization, antimicrobial resistance is already one of the main threats to global public health, with the potential to cause up to 10 million deaths per year by 2050. In several studies, resistant strains have been detected in aquatic environments. Extreme situations, such as wars and pandemics, can accelerate the problem of antimicrobial resistance, making it even more difficult to control.
Emerging pollutants not only affect biodiversity and human health, but also the economy. The disruption of aquatic food chains can reduce local fishing, and the perception of contaminated waters negatively impacts tourism in natural areas. For example, in Lake Chapala and other bodies of water in Mexico, the perception of pollution has resulted in economic losses for riverside communities that depend on these ecosystems.
What can we do?
Given this outlook, it is urgent to foster more interdisciplinary research to detect, quantify, and understand the effects of these pollutants. Likewise, it is necessary to update regulatory frameworks to incorporate limits and monitoring mechanisms for emerging substances. Improvements are also needed in wastewater treatment systems through advanced technologies such as nanofiltration and ultrafiltration membranes, adsorbents based on sustainable materials (synthetic biochar), ozonation, or advanced oxidation processes.
At a societal level, a culture of responsible consumption and disposal must be promoted: avoiding throwing medications down the toilet or sink, reducing the use of plastics, and choosing personal care products free of harmful substances are actions within everyone’s reach. For example, one can prefer using shampoos, soaps, and deodorants labeled as “paraben-free” or “triclosan-free,” since these compounds are often associated with toxic effects on aquatic organisms.
Emerging pollutants represent a real, though invisible, threat to the health of people and ecosystems. Although their concentrations are usually low, their cumulative effects can be significant. We cannot protect what we cannot see, but we can act based on existing scientific evidence. A coordinated effort is urgent among scientists, authorities, the private sector, and citizens to stop the advance of these compounds and ensure the right to clean and safe water for present and future generations.