I would say it has been repeatedly reported for over 50 years that antibiotics end up in rivers or lakes etc. What is the point! This seems to be a piece of junk science!
Also one of those never dying and often repeated narratives!
This study is based on computer modeling! Junk model? Garbage in, garbage out?
Lots of estimates and thresholds! How relevant are these thresholds?
What do the authors mean by "human consumption alone represents a significant risk for rivers across all continents"? So should we not consume antibiotics anymore?
It is odd that the authors did not bother to mention wastewater treatment in the abstract nor in the significance chapter. This is shoddy science!
Caveat: I did not read the study!
"Nearly a third of antibiotics consumed by people end up in rivers, per a PNAS modeling study from McGill University and One Health Trust researchers that estimates the distribution of chemical pollutants from untreated wastewater and wastewater treatment plants."
"... Much of the focus has been on the antibiotic manufacturing process, which is known to release antibiotic-laced wastewater directly into nearby waterways. That has resulted in efforts to monitor and limit pollution from antibiotic manufacturing sites.
But since antibiotics consumed by people aren't fully metabolized, wastewaters from households and hospitals are also potential sources of antibiotic contamination. And while wastewater treatment plants can remove some antibiotic residues before the treated water is released into surface waters, they can't remove all of them [???]. ...
The researchers also estimated that 750 million people—roughly 10% of the global population—are exposed [???] to the top 1% of surface waters with the highest cumulative concentrations of antibiotics. ...
The authors say the findings suggest an "urgent need" [???] for further research on the environmental fate and impact of the antibiotics that their model predicts are most prevalent in surface waters, particularly those that pose a high potential risk to aquatic ecosystems and human health. ..."
From the abstract:
"The presence of antibiotics in surface waters poses risks to aquatic ecosystems and human health due to their toxicity and influence on antimicrobial resistance. After human consumption and partial metabolism, antibiotic residues are excreted and undergo complex accumulation and decay processes along their pathway from wastewater to natural river systems.
Here, we use a global contaminant fate model to estimate that of
the annual human consumption of the 40 most used antibiotics (29,200 tonnes),
8,500 tonnes (29%) are released into the river system and
3,300 tonnes (11%) reach the world's oceans or inland sinks.
Even when only domestic sources are considered (i.e. not including veterinary or industrial sources),
we estimate that 6 million km of rivers worldwide are subject to total antibiotic concentrations in excess of thresholds that are protective of ecosystems and resistance promotion during low streamflow conditions,
with the dominant contributors being amoxicillin, ceftriaxone, and cefixime. Therefore, it is of concern that human consumption alone represents a significant risk for rivers across all continents, with the largest extents found in Southeast Asia. Global antibiotic consumption has grown rapidly over the last 15 years and continues to increase, particularly in low- and middle-income countries, requiring new strategies to safeguard water quality and protect human and ecosystem health."
"Significance Statement
Antibiotic contamination in global rivers poses significant threats to aquatic ecosystems and human health. Our model predicts that 8,500 tonnes of antibiotics enter river systems annually from domestic consumption alone, causing elevated concentrations of various antibiotics in rivers across all continents. For example, estimated concentrations of antibiotics in 6 million km of rivers worldwide exceed thresholds that are protective of ecosystems and/or resistance promotion, with the most impacted regions located in Southeast Asia. As global antibiotic consumption rises, especially in low- and middle-income countries, these findings underscore the urgent need for the development and implementation of strategies to minimize antibiotic pollution and safeguard environmental and human health."
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Fig. 1 Contaminant pathways of antibiotics in the global aquatic environment. Modeled contaminant pathways and mass balances of antibiotics by path. Values in parentheses indicate total amounts of the top 40 antibiotics consumed worldwide in tonnes year−1; percentage values are relative to the total excretion amount (20,500 tonnes year−1).
