Anti-infectives have become environmental contaminants of growing concern, as they are transported from landfills, agriculture and urban centers into waterways and drinking water, according to a review article published in the May 2009 issue of the journal Environmental Health Perspectives (EHP). The authors suggest that “only highly contaminated waters could affect the most sensitive [aquatic] species,” but when considering the potential of high anti-infective concentrations to contribute to the spread of antibiotic resistance in bacteria, indirect impact on human health must be considered.
Anti-infectives comprise several classes of biologically active compounds such as antibiotics, synthetic sources such as antimicrobials and some antifungals. Anti-infectives are constantly discharged at trace levels in natural waters near urban centers and agricultural areas. They represent a cause for concern because of their potential contribution to the spread of anti-infective resistance in bacteria and other effects on aquatic biota.
Available data concerning three classes of antibiotics (macrolides, quinolones and sulfonamides) and the individual compound trimethoprim in urban wastewater in three geographic areas (East Asia, Europe and North America) indicated significantly higher concentrations of these products in raw wastewater compared with treated wastewater.
The authors cite research suggesting that the current tendency toward concentrated animal feeding operations means the occurrence of anti-infectives in agricultural wastewater may increase in the near future. Moreover, urban water conservation strategies, while critical for ensuring adequate water supplies, also mean lower wastewater volumes and thus an increase in anti-infective levels because of lower dilution.
“More research is necessary, especially for low- to middle-income countries, which may be more impacted by anti-infective contamination than high-income countries because of less extended public sewage infrastructures, higher rates of self-prescription and often less strict industrial emissions legislations,” write first author Pedro A. Segura and colleagues.
“The cumulative effects of anti-infectives in wastewater are not yet known,” said EHP editor-in-chief Hugh A. Tilson, PhD. “Further studies need to be conducted to moderate the impact of anti-infectives in the aquatic environment in the future.”
Other authors of the paper included Matthieu François, Christian Gagnon and Sébastien Sauvé. This study was supported by the Fonds de Recherche sur la Nature et les Technologies du Québec, the St. Lawrence Action Plan, the Natural Sciences and Engineering Research Council of Canada and the Canadian Foundation for Innovation.