Although the world is becoming more environmentally conscious, scientific studies reveal that invisible pollutants such as antibiotics, pharmaceuticals, cosmetics, and industrial waste are finding their way into rivers, oceans, and even drinking water. Ricardo Salazar-González, a researcher at SERC Chile–UC, is working on an innovative solution: using solar radiation to eliminate these pollutants. He is also proposing new regulations to measure and control them.

Unfortunately, plastic bottles, bags, and nets floating in rivers and oceans have become a common sight. Although environmental awareness has grown, there is still an invisible threat that is rarely discussed: emerging contaminants—compounds that silently seep into our waters.

These include contaminants such as pharmaceuticals, pesticides, microplastics, and other chemical compounds that, as explained by Ricardo Salazar-González, a researcher at the Solar Energy Research Center (SERC Chile) and director of the WATER² group, “are contaminating water sources at an alarming rate. “These substances are overlooked by current monitoring and regulatory systems and require careful attention due to their potential effects on aquatic ecosystems and, consequently, on human health.”

The UC professor also emphasizes that “all the products we consume or use on a daily basis contain chemical compounds that sooner or later end up in the water. They seep in, accumulate, and we don’t measure them.”

For example, in 2024, the Chilean salmon industry used 351.1 metric tons of antimicrobials, according to official data from SERNAPESCA. Of that total, more than 98% was administered during the seawater farming phase, representing a 10.8% increase compared to 2023, which exacerbates its potential environmental impact.

“We’re talking about a cocktail of highly concentrated antibiotics that we’re releasing into coastal ecosystems without a clear understanding of their long-term consequences,” warns Salazar-González. “Not only are we promoting bacterial resistance, but we also lack the mechanisms to track what happens afterward.”

In light of this, Salazar-González emphasizes that “it is not enough to simply improve production practices. A robust regulatory framework is needed—one that establishes clear limits, reduction targets, mandatory transparency, and, above all, environmental monitoring. Today, in Chile, there is no systematic network or legal mandate to monitor antimicrobials or resistance genes in bodies of water, whether inland or marine. Nor is there a requirement to assess their presence in sediments or in native wildlife.”

Among these emerging contaminants are microplastics, which include remnants of cosmetics, synthetic fibers from clothing, and waste from the automotive industry, among many others. And as Salazar-González warns, “the problem is not just that they are everywhere, but that they persist.” These particles act as carriers of chemical contaminants such as pesticides, pharmaceuticals, and heavy metals, as well as pathogenic microorganisms. They can even interfere with wastewater treatment processes by transporting genes for antimicrobial resistance and undermining the effectiveness of our current technologies.”

As part of the challenge of regulating these pollutants and measuring their impact on ecosystems, the research team led by Ricardo Salazar-González is working on a legislative proposal spearheaded by SERC Chile, in collaboration with the Pontifical Catholic University of Chile, the Center for Public Policy (CPP), and the Center for Water Law and Management (CDGA). The initiative aims to create a National Network for Environmental Monitoring of Antimicrobials, organized under the “One Health” approach.

This network would make it possible to systematically monitor wastewater, rivers, areas of intensive farming, and marine environments, providing—for the first time—environmental traceability for what currently flows unchecked. “It’s not enough to improve production practices. If we don’t measure what we release into the environment, we’ll never be able to manage it. The science is already there; now it’s up to policymakers,” emphasizes Salazar-González.

Solar Potential

According to research conducted by Salazar-González, along with other scholars, advanced electrochemical oxidation processes (EAOP) offer hope. Using this technology and solar radiation, they have succeeded in removing emerging contaminants and disinfecting contaminated water in real-world settings.

“Water can be decontaminated using solar photochemistry. This involves harnessing the sun’s UV radiation, which helps generate oxidizing species and break down the contaminants present in the water. In addition, solar energy can be used to power the water treatment system, making it more efficient.”

“In one of our most recent studies, we were able to remove emerging contaminants from real-world water samples while also disinfecting the water. In other words, it is 100% effective at breaking down recalcitrant chemical compounds and pathogenic microorganisms,” says Salazar-González.

And, as if that weren’t enough, solar photoreactors are inexpensive, and their size can be adapted to the volume to be treated. “And from an energy standpoint, it’s possible to harness photovoltaic solar energy to power the system,” says Salazar-González.