Antibiotic Pollution in Rivers from Human Use Raises Global Concerns

A global investigation released today warns that thousands of kilometers of river systems worldwide are contaminated with antibiotics at levels high enough to encourage the development of drug resistance and to kill aquatic life. Performed by McGill University and published in PNAS Nexus, the investigation is the first to put numbers on the global scale of river contamination resulting from human consumption of antibiotics.

People around the world take huge quantities of antibiotics annually to treat infections and other illnesses. In its own research, nearly 8,500 tons of the drugs—close to one-third of what is consumed yearly—are entering rivers. This even happens when wastewater often already passes through water treatment plants before reaching rivers. Even the largest water treatment plants cannot remove such drug products to a zero level, especially from developing countries that have limited infrastructure.

While the level of most antibiotics in most rivers is infinitesimal, their frequent appearance annually cumulates. Cumulative exposure over long periods raises the risk of harmful effects on aquatic ecosystems and to the world-wide spread of antimicrobial resistance (AMR). AMR occurs when bacteria become resistant to the action of antibiotics, making infections otherwise easily treated more difficult to treat and more likely to be transmitted, to cause severe disease, and to kill.

The researchers assert they used a global model calibrated to field measurements in approximately 900 river locations around the world. The research utilized all traditional medicines common drugs and pesticides, but the findings most strongly point toward common antibiotic amoxicillin as the most likely substance common drugs common drugs to look for in rivers. The issue is most critical in Southeast Asia, where antibiotic use is increasing and sewage treatment is not as advanced.

One of the key findings made by the research is that the calculation of pollution doesn't include antibiotic use in agriculture or those from plants that make them—both of which are known sources of significant environmental pollution. The implication is that the actual level of antibiotic presence within river networks is higher than what the research indicates.

By isolating only the antibiotics from human use, the study emphasizes that even that single source by itself is sufficient to initiate serious threats. The authors comment that it is an issue of international concern that requires prompt action, particularly where infrastructure for adequate wastewater treatment is not present in certain areas.

The presence of antibiotics in rivers has more than microbial community impacts. Long-term exposure to these chemicals also harms aquatic animals. Fish, amphibians, and invertebrates suffer from growth impairments, reproductive defects, and increased susceptibility to disease. This has long-term effects on biodiversity and destroys the balance of freshwater communities.

Another problem uncovered by the study is the imbalance of tracking the environment at the global scale. There are no or very few programs to track chemical contaminants in water networks in the majority of high-risk areas defined by the model. Without information like that, it's impossible to understand the scale of the problem and come up with good solutions to mitigate it.

The authors recommend to policymakers that the environmental monitoring systems must be upgraded, especially in regions that are likely to pose a high risk. Monitoring of antibiotics in river systems is among the most vital work in following up on sources of pollution and identifying the spread of antibiotic resistance. This also provides valuable data to be used in designing effective wastewater treatment systems capable of destroying drug residues.

Although the study is not discouraging the application of antibiotics in medicine—still useful for infection elimination and life saving—it calls for the need to have better waste management, as well as international collaboration geared towards reducing environmental pollution. The remedy could be through enhancing water treatment plants, regulating disposal of antibiotics, as well as investing in research to come up with more environmentally friendly drugs that also break down quicker in the environment.

The research is one of an increasingly large body of evidence illustrating the way in which human activity is unknowingly affecting natural water systems. As countries transition towards sustainable development and public health goals, treatment of pharmaceutical pollution will be a key aspect of human and environmental protection.

Source and Credits:
McGill University via PNAS Nexus