Antibiotic contamination in freshwater poses huge environmental risk

Antibiotic resistance is one of the biggest threats to global health and development, according to the World Health Organization (WHO). Once easily treatable infections are becoming more and more resistant to antibiotics and research has shown that the environment plays a major role in the spread of antibiotic-resistant bacteria.

Now, a new study conducted by researchers from Radboud University is the first to review the increase in antibiotic levels in global freshwater sources over the past 20 years and assess the environmental risks posed by contaminated watersheds.

The study was published in the journal Environmental Research Letters.

“Generally, it’s seen as a problem for the health sector, as resistant bacteria can be spread within hospitals or through livestock,” said Rik Oldenkamp, the lead author of the study. “But there’s little awareness of the role of the environment in this problem, even though it becomes increasingly clear that the environment functions as a source of resistance for various pathogens.”

The researchers focused on two popular drugs, an antibiotic called ciprofloxacin and an anti-epileptic called carbamazepine.

Environmental risks of ciprofloxacin in fresh water,
Image Credit: R. Oldenkamp et al, Environmental Research Letters

Socio-economic and demographic information, as well access to wastewater treatment, pharmaceutical consumption, and available freshwater resources, were used to build on past models which allowed the researchers to more accurately model environmental risks by ecoregion.

“Our model shows a particular need for new data in these types of areas,” said Oldenkamp. “The model is really a starting point for creating an insight into the environmental risks posed by pharmaceuticals all over the world.”

The researchers found that in 2015, the environmental risks posed by the two drugs were ten to 20 times higher compared to 1995. Ciprofloxacin, in particular, is being used so much that contaminate levels could cause serious damage to the ecosystem.

“The concentrations of this antibiotic can be harmful for bacteria in the water, and these bacteria in turn play an important role in various nutrient cycles,” said Oldenkamp. “Antibiotics can also have a negative impact on the effectiveness of bacteria colonies used in wastewater treatment.”

The results highlight how limited global data is on pharmaceutical use and antibiotic contamination levels in freshwater resources, according to Oldenkamp who says that data is key to understanding the scope of freshwater antibiotic concentrations.

“Getting an accurate picture of the environmental risks of pharmaceuticals around the world depends on the availability of data, which is limited,” said Oldenkamp. “It’s true that there are models, such as the ePiE model, which can give detailed predictions of pharmaceutical concentrations in the environment, but these are often only applicable to places where we already have a lot of information, such as rivers in Europe.”

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By Kay Vandette, Earth.com Staff Writer