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We Were Fighting The Wrong Villain

A new study shows that glyphosate contamination in rivers stems largely from urban sources, challenging previous assumptions

Glyphosates, the world’s most widely used herbicides, have long been assumed to be a major pollutant in rivers and waterways. These chemicals can be very scary, let me tell you. Although researchers are still debating its potential harms, major health risks for humans may include cancer, liver and kidney damage, and endocrine and reproductive issues.

What did we blame glyphosate pollution on? Agricultural runoff. We knew farmers used it, so it made sense, right? I have witnessed many campaigns trying to regulate this pollutant and always blaming it on the farmers.

However, new research from the University of Tübingen challenges this notion, revealing that the primary source of glyphosate in European rivers might not be farming at all. Instead, this herbicide might enter our waterways through a surprising route: household detergents.

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In a comprehensive study led by Professor Carolin Huhn, researchers conducted a large meta-analysis of data from various water protection authorities in Europe and the USA. This study, published in the journal Water Research, suggests that the glyphosate found in European rivers is largely derived from urban wastewater, not agricultural fields.

What a turn of events!

To unravel the mystery of glyphosate contamination, Dr. Huhn and her team examined long-term data sets spanning over two decades, collected from approximately 100 sites across Europe and the USA. These data sets included glyphosate and its main transformation product, aminomethylphosphonic acid (AMPA), in river waters.

Here’s where this story gets interesting. Researchers found this by following clues like detectives. Let’s see how.

The researchers meticulously analyzed the temporal patterns of glyphosate concentrations, comparing them with other agricultural markers and pollutants commonly found in wastewater.

In European rivers (left panel), glyphosate and its transformation product AMPA show seasonal patterns similar to wastewater markers like carbamazepine, indicating a dominant input from wastewater treatment plants. Conversely, in the USA (right panel), glyphosate and AMPA concentrations correlate with agricultural herbicides like metolachlor, suggesting agricultural runoff as the primary source. The Spearman rank correlation plots (center) further illustrate this difference, showing higher corre
In European rivers (left panel), glyphosate and its transformation product AMPA show seasonal patterns similar to wastewater markers like carbamazepine, indicating a dominant input from wastewater treatment plants. Conversely, in the USA (right panel), glyphosate and AMPA concentrations correlate with agricultural herbicides like metolachlor, suggesting agricultural runoff as the primary source. The Spearman rank correlation plots (center) further illustrate this difference, showing higher correlations between glyphosate and pharmaceuticals in Europe and between glyphosate and herbicides in the USA. The bottom panels depict the primary pathways of glyphosate into rivers: urban wastewater in Europe and agricultural runoff in the USA. — Schwientek, M., et al. “Glyphosate Contamination in European Rivers Not from Herbicide Application?” Water Research, 2024, p. 122140, https://doi.org/10.1016/j.watres.2024.122140. Accessed 26 Jul. 2024.

One of the standout observations was the seasonal pattern of glyphosate concentrations in European rivers. The study noted high levels of glyphosate during summer and lower levels in winter, a pattern inconsistent with agricultural application, which typically peaks in spring and autumn.

They had a clue here. This seasonal fluctuation was similar to other substances known to enter surface waters from wastewater treatment plants, such as pharmaceuticals and household chemicals.

In stark contrast, data from the USA showed glyphosate concentrations spiking in response to rain events following herbicide application, aligning with expected agricultural runoff. This clear pattern difference between the continents prompted the researchers to investigate into potential non-agricultural sources of glyphosate in Europe.

agricultural fields
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The research team hypothesized that glyphosate in European rivers might be a transformation product of aminopolyphosphonates, compounds commonly used in laundry detergents and other cleaning products. When processed in wastewater treatment plants, these compounds could break down into glyphosate and AMPA.

So they jump into testing this hypothesis, and…

Initial laboratory tests confirmed this hypothesis, showing the formation of glyphosate from these detergent additives under conditions similar to those in wastewater treatment plants.

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As Professor Huhn stated, “The detailed analysis of the millions of individual values shows us that municipal wastewater plays a role. And some of the findings of the study also show us that we have to locate a source for glyphosate close to households.”

This suggests a significant urban contribution to glyphosate pollution in Europe, separate from direct herbicide application. Yes, once again, urban settings are to blame.

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But I know what you may be thinking. Why glyphosate contamination from wastewater doesn’t happen in the USA as it does in Europe?

The authors attribute this difference primarily to the varying use of aminopolyphosphonates between the two regions. In Europe, these compounds are extensively used in laundry detergents and other cleaning products. When processed in wastewater treatment plants, they can break down into glyphosate and AMPA.

Conversely, in the USA, aminopolyphosphonates are hardly used in household detergents. This means that the primary source of glyphosate in US rivers remains agricultural runoff, as opposed to the wastewater-derived glyphosate seen in Europe. This discrepancy highlights how regional differences in product formulations can significantly impact environmental pollution pathways.

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This discovery has far-reaching implications for environmental policy and water quality management. If glyphosate is indeed entering waterways primarily through urban wastewater then, current strategies focused solely on reducing agricultural herbicide use might be insufficient.

If they decide to take science seriously, regulatory bodies may need to consider monitoring and potentially regulating the use of aminopolyphosphonates in household products.

Furthermore, the study underscores the complexity of environmental pollution and the need for a holistic approach to tackling it. It highlights the importance of considering multiple sources and pathways of contaminants to develop effective mitigation strategies. The need to stop making assumptions that ultimately don’t hold true.

On the other hand, this research offers the public a new perspective on everyday activities and their environmental impact. Although the blame shouldn’t be put on the consumer solely, simple actions like doing laundry might contribute to a larger issue of river pollution, reminding us that our household choices can have significant environmental consequences.

Box-whisker-plots of Spearman rank correlation coefficients for rank correlation analysis of glyphosate with AMPA, with available data on herbicides and carbamazepine from selected sites in the USA and Europe. A correlation coefficient of 1 indicates a perfect positive, a coefficient of -1 a perfect negative relationship of the variables’ ranks. The number of analyzed time series is indicated by n. Data in Tables S3 and S4 — Schwientek, M., et al. “Glyphosate Contamination in European Rivers Not from Herbicide Application?” Water Research, 2024, p. 122140, https://doi.org/10.1016/j.watres.2024.122140. Accessed 26 Jul. 2024.

The findings also provide a broader lesson about the interconnectedness of human activities and natural ecosystems. The unexpected link between household detergents and river pollution exemplifies how industrial and domestic practices can have disastrous environmental impacts. This calls for increased awareness and responsibility in product production, usage, and disposal practices.

Solving environmental problems requires innovation, collaboration, and a willingness to look beyond traditional assumptions. This research is a step forward in this direction, offering new insights and prompting a reevaluation of how we address pollution in our rivers and waterways.

The discovery that glyphosate in European rivers may largely come from household detergents rather than farming is surprising (at least it is to me). Still, it opens up new avenues for improving water quality and protecting our natural environments. This research emphasizes the need for comprehensive environmental monitoring and more effective pollution control strategies that consider all potential sources of contamination.

As always, we are trying to improve our environment, one scientific discovery at a time!

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