Micropollutants: What Are These Molecules That Contaminate Our Water?
Today, our aquatic environments are polluted by a wide variety of waste and chemical compounds. Some of these pollutants are invisible to the naked eye. These are known as micropollutants. They are chemical compounds found in aquatic environments at very low concentrations.
Geoffroy Duporté, University of Montpellier
By way of comparison, the minerals found in drinking water—such as calcium, potassium, and magnesium—are present in concentrations that are one thousand to one million times higher than those of a micropollutant.
The concentrations of these micropollutants are equivalent to a single sugar cube in an Olympic-sized swimming pool. Obviously, if you take a sip, you won’t be able to taste the sweetness of the water, but unfortunately, even at these minute concentrations, some of these molecules can have negative effects on the environment, living organisms, and biodiversity due to their toxicity, persistence, and bioaccumulation.
Where do micropollutants come from?
There are many sources of micropollutants in the environment. Although there are natural sources (such as volcanoes, which emit large amounts of hydrocarbons), micropollutants are generally of human origin (industry, transportation, agriculture, and household activities).
Currently, more than 100,000 chemicals are classified as micropollutants by the European Union. Many of the products we use every day contain them: cosmetics, medications, cleaning products, paints, and more.
The sources of water contamination by micropollutants are thus very diverse:
- Domestic wastewater plays a significant role in the transfer of these contaminants to aquatic environments. Although wastewater treatment plants are capable of removing some micropollutants, certain molecules enter aquatic environments without being removed. These include pharmaceutical residues (paracetamol, antidepressants, etc.), phthalates (molecules derived from the use of plastics), parabens (from cosmetics), UV filters found in sunscreen, and pesticides such as antiparasitic products used for pets, are examples of micropollutants commonly found in this domestic wastewater.
- Industrial wastewater also releases numerous pollutants associated with the relevant activities (plastics, detergents, solvents, petroleum products, metals, etc.).
- Hospital wastewater also contributes to the contamination of wastewater with pharmaceutical residues. In particular, it contains many antibiotics, anticancer drugs, and contrast agents.
- Contaminants can also originate from agricultural sources, such as soil pollution caused by pesticides or antibiotics administered to livestock. These micropollutants contribute to the contamination of aquatic environments through runoff or seepage.
This pollution flows into groundwater, streams, rivers, seas, and oceans. This invisible pollution thus also ends up in our drinking water supplies.
The fight against micropollutants is now a major environmental and public health issue. To illustrate this problem, a scientific study shows the widespread presence of pharmaceutical residues in 258 rivers around the world. The most commonly found molecules are carbamazepine (an antiepileptic), metformin (an antidiabetic), and caffeine. This study shows that at 25% of the sites studied, concentrations of at least one pharmaceutical residue exceeded levels that would have an impact on aquatic organisms.
For example, another scientific study assessed caffeine residues in aquatic environments as a contaminant of concern. This compound has been found in the tissues of coastal and marine organisms (microalgae, coral reefs, mollusks, and fish). Furthermore, it has been demonstrated that these caffeine residues can, for example, affect the reproduction and development of aquatic organisms.
This article is published as part of the “Questions from Young People to Research initiative led by Agropolis International in partnership with the Montpellier Academy’s Office of Education.
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Geoffroy Duporté, Associate Professor of Environmental Chemistry, University of Montpellier
This article is republished from The Conversation under a Creative Commons license. Readthe original article.