A recent study by researchers from The Nature Conservancy, Catalan Institute for Water Research, and University of Girona revealed extensive overlap of wastewater pollution hotspots with natural habitats, with highly contaminated areas as large as tens of thousands of square kilometers.
Growing demand for pharmaceuticals and personal care products have accelerated the creation and use of novel chemicals. But the latest ingredients in our soaps and shampoos may be contributing to a substantial problem that our wastewater systems are unequipped to treat. Pollutants like heavy metals and endocrine disruptors are rapidly entering and accumulating in the environment, with unseen consequences to biodiversity and ecological health.
To understand the extent of this problem, the study’s researchers used concentration estimates of diclofenac to model the spread of wastewater pollution in the environment. Diclofenac (DCL) is a nonsteroidal anti-inflammatory drug commonly used to treat pain, migraines, and arthritis. Only 40% of the drug is removed during the wastewater treatment process, and upon release into the environment, it can persist in waterways for months.
The researchers found that roughly 31% of salt marshes and 56% of fish-rich rivers worldwide have critical levels of DCL pollution. Marine regions are also being hit hard, with coral reefs heavily impacted by sewage contamination in the Western and Central Indo-Pacific and the Tropical Atlantic.
Additionally, the researchers demonstrated that wastewater pollution is universal, regardless of the presence (or lack thereof) of sanitation management. They identified contamination hotspots near well-developed cities with practically universal sanitation in Germany and the United States, as well as large swaths of pollution across both developing and developed nations like India and the United Kingdom.
The researchers mapped the severity of urban wastewater pollution for regions with coral reefs and salt marshes by modeling loading of diclofenac (DCL, g/km/year).
By comparing these two maps, the researchers highlighted how freshwater ecoregions with high fish species richness overlap extensively with those that have high predicted diclofenac loading.
This study and others have shown that the wastewater pollution problem transcends boundaries and backgrounds – accordingly, our solutions will require collaboration and engagement across sectors and geographies. Luckily, progress is already being made. Interest has been ramping among conservation and sanitation practitioners, who are beginning to organize around this issue to collectively problem-solve together.
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