Year: 2004
Type: report
Abstract: More than 50 million pounds of antibiotics are produced in the United States each year, approximately one-half of which are prescribed for human use and one-half for agriculture.When used with livestock (for example, swine, poultry, and cattle), the majority of these antibiotics are given in subtherapeutic doses as feed additives to enhance growth.Antibiotics are also used in aquaculture and sprayed on fruit trees to inhibit fungal growth.These findings have raised concern, not only that pharmaceutical compounds will find their way into our water systems, but also that they may have detrimental effects on ecological and human health.Because little is known about the occurrence, fate, and transport of antibiotics in the environment, it is important to begin assessing where they may occur and at what levels.Some of these compounds have been detected at low concentrations in some of the lakes, rivers, and ground waters in Europe and across the United States but no surveillance of source waters that supply drinking water treatment plants had been previously undertaken in North Carolina.With evidence that these chemicals survive wastewater treatment and given the geographical location of many of the state's drinking water treatment plants downstream of wastewater treatment plant (WWTP) discharges, this study set out to evaluate whether pharmaceutical compounds persisted in North Carolina drinking water.This study set out to first develop and validate analytical methods for determining the occurrence of 22 antibiotics in raw (source) and finished drinking waters.The methods that evolved accounted for interferences from natural organic matter (NOM) and residual disinfectants.The methods were applied in waters from the drinking water treatment plants of several members of the North Carolina Urban Water Consortium (NCUWC).Some of the source waters at these plants were likely impacted by upstream WWTP effluents, while others were located in watersheds in which there are large concentrations of animal feeding operations.Quantitation limits down to 10 ng/L for some of the target antibiotics enabled some preliminary evaluation of the effectiveness of conventional treatment on their apparent removal.Overall, fluoroquinolones were the most frequently detected in source waters, followed by sulfonamides, lincomycin, tetracyclines, and macrolides.Although the detection of ciprofloxacin, which is used only in human medication, seems to indicate impact from human wastewater discharges, the possibility of contamination from animal sources should not be excluded, as the veterinary fluoroquinolone enrofloxacin can, under certain conditions, be metabolized to ciprofloxacin.In most of the treatment plants the finished waters either chlorinated or chloraminated, showed either no detectable antibiotic residues or very much reduced levels.However, it is not known whether these compounds were physically removed during treatment, such as by adsorption to filters or precipitation in coagulation basins, or were merely chemically converted during disinfection processes.Any of these pathways may contribute to accumulation of the target compounds in the vi environment, and it is essential that their fate and transport mechanisms be better understood if human health is not to be compromised.
Language: English
Subfield: Pollution
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2184427859