Residue levels of antibiotics are particularly high in waterways and water treatment plants and are contributing to antibiotic resistance, according to a new study. 

This is a serious global human health threat as it can potentially be transferred to drinking water and hinder medication’s effectiveness against bacterial infections.

According to the study published in the journal Lancet Planetary Health, antibiotics are generally detected in aquatic sources such as drinking water, rivers, etc in the Western Pacific Region (WPR) and the South-East Asia Region (SEAR). Both China and India, which belong to the WPR and SEAR respectively, are among the largest producers and consumers of antibiotics in the world.

The research team in Sweden found over 92 antibiotics in the Western Pacific Region and 45 antibiotics in the South-East Asia Region. These antibiotic levels, which were observed to exceed safety limits for resistance development for most antibiotic classes, were found in wastewater, influents, and effluents of wastewater treatment plants and seas that receive waste.

The highest levels were found in wastewater and influents of wastewater treatment plants.

Meanwhile, in the sea, the antibiotic Ciprofloxacin was found in large amounts in tap or drinking water of the West Pacific Region and China, exceeding the threshold considered safe for resistance development. 

”Our results can help decision-makers to target risk reduction measures against environmental residues of priority antibiotics and in high-risk sites, to protect human health and the environment,” says the study’s lead author Nada Hanna who is also a researcher at the Department of Global Public Health at Karolinska Institutet. “Allocating these resources efficiently is especially vital for resource-poor countries that produce large amounts of antibiotics.”

The environment plays a huge role in the spread of antibiotic resistance. Antibiotics can enter the environment through wastewater and waste from different sources—that includes hospitals, pharmaceutical companies, agriculture production, etc.—during their production, consumption, and elimination. They can also enter through urine and feces excreted into waste streams.

The team reiterates that the levels of antibiotic residues in wastewater and wastewater treatment plants serve as potential “hotspots” for the growth of antibiotic resistance in these regions and present a possible threat to the environment and human health through exposure to various sources of water, including our drinking water.

The team arrived at these findings after conducting a systematic review of studies published between 2006 and 2019 that contained measurements of antibiotic residue levels in aquatic environments. 218 relevant studies from the Western Pacific Region and 22 relevant studies from the South-East Asia Regions were likewise included.

In addition, the study authors used a method known as probabilistic environmental hazard assessment to discover where the concentration of antibiotics is high enough to possibly contribute to antibiotic resistance.

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