Antibiotic residues in sewage and wastewater treatment plants in regions around China and India are likely to contribute to antibiotic resistance, and drinking water may pose a threat to human health, according to comprehensive analysis of the Karolinska Institutet published on The Lancet’s planetary health. Researchers also determined the relative contributions of various sources of antibiotic contamination in waterways, such as hospitals, municipalities, livestock and pharmaceutical manufacturing.
Our findings can help decision-makers target risk reduction measures against environmental residues of priority antibiotics and at high-risk sites to protect human health and the environment. Allocating these resources efficiently is especially vital for resource-poor countries that produce large quantities of antibiotics.”
Nada Hanna, researcher in the department of global public health at Karolinska Institutet in Sweden and first author of the study
Bacteria that become resistant to antibiotics are a global threat that can lead to untreatable bacterial infections in animals and humans.
Antibiotics can enter the environment during their production, consumption and disposal. Antibiotic residues in the environment, such as in wastewater and drinking water, can contribute to the emergence and spread of resistance.
Among the major producers of antibiotics
Researchers examined levels of antibiotic residues that may contribute to antibiotic resistance from different aquatic sources in the Western Pacific Region (WPR) and Southeast Asia Region (SEAR), regions defined by the World Health Organization. These regions include China and India, which are among the world’s largest producers and consumers of antibiotics.
This was done through a systematic review of the literature published between 2006 and 2019, including 218 relevant reports from WPR and 22 from SEAR. The researchers also used a method called Probabilistic Environmental Hazard Assessment to determine where the concentration of antibiotics is high enough to likely contribute to antibiotic resistance.
Ninety-two antibiotics were detected in the WPR and forty-five in the SEAR. Concentrations of antibiotics above the level considered safe for the development of resistance (Predicted No Effect Concentrations, PNECs) have been observed in wastewater, effluents and effluents of wastewater treatment plants and receiving aquatic environments. The highest risk was observed in wastewater and in the influent of wastewater treatment plants. The relative impact of various contributors, such as hospital, municipal, animal husbandry and pharmaceutical manufacturing was also determined.
Potential threat to human health
In receiving aquatic environments, the highest likelihood of levels above the threshold considered safe for the development of resistance was observed for the antibiotic ciprofloxacin in drinking water in China and in the WPR.
“Antibiotic residues in sewage and wastewater treatment plants can serve as hot spots for the development of antibiotic resistance in these regions and pose a potential threat to human health through exposure to different water sources, including drinking water,” says Nada Hanna.
Limitations to consider in interpreting the results are the lack of data on the environmental occurrence of antibiotics from many of the countries in the regions and the fact that only studies written in English were included.
The research was funded by the Swedish Research Council.
Anne, N. et al. (2023) Antibiotic concentrations and antibiotic resistance in aquatic environments of the WHO West Pacific and Southeast Asia regions: A systematic review and probabilistic environmental risk assessment. The Lancet’s planetary health. doi.org/10.1016/S2542-5196(22)00254-6.