Veterinary pharmaceuticals (VPs) increasingly used in animal husbandry have led to their presence in aquatic environments -surface water (SW) or groundwater (GW) - and even in tap water. This review focuses on studies from 2007 to 2017. Sixty-eight different veterinary pharmaceutical residues (VPRs) have been quantified worldwide in natural waters at concentrations ranging from nanograms per liter (ng L) to several micrograms per liter (μg L). An extensive up-to-date on sales and tonnages of VPs worldwide has been performed. Tetracyclines (TCs) antibiotics are the most sold veterinary pharmaceuticals worldwide. An overview of VPRs degradation pathways in natural waters is provided. VPRs can be degraded or transformed by biodegradation, hydrolysis or photolysis. Photo-degradation appears to be the major degradation pathway in SW. This review then reports occurrences of VPRs found in tap water, and presents data on VPRs removal in drinking water treatment plants (DWTPs) at each step of the process. VPRs have been quantified in tap water at ng L concentration levels in four studies of the eleven studies dealing with VPRs occurrence in tap water. Overall removals of VPRs in DWTPs generally exceed 90% and advanced treatment processes (oxidation processes, adsorption on activated carbon, membrane filtration) greatly contribute to these removals. However, studies performed on full-scale DWTPs are scarce. A large majority of fate studies in DWTPs have been conducted under laboratory at environmentally irrelevant conditions (high concentration of VPRs (mg L), use of deionized water instead of natural water, high concentration of oxidant, high contact time etc.). Also, studies on VPRs occurrence and fate in tap water focus on antibiotics. There is a scientific gap on the occurrence and fate of antiparatic drugs in tap waters.

In intensive livestock areas, veterinary pharmaceutical residues (VPRs) can occur in water resources, but also in tap water because treatment processes are not designed to remove these contaminants. The main objective of this study is to assess the occurrence of VPRs in water resources and tap waters in Brittany. As several identical compounds are used in both veterinary and human medicine, a toolbox (stanols and pharmaceuticals) is used to help determine the origin of contamination in the case of mixed-use molecules. Water resources samples were collected from 25 sites (23 surface waters and two groundwaters) used for tap water production and located in watersheds considered as sensitive due to intensive husbandry activities. Samples were also taken at 23 corresponding tap water sites. A list of 38 VPRs of interest was analyzed. In water resources, at least one VPR was quantified in 32% of the samples. 17 different VPRs were quantified, including antibiotics, antiparasitic drugs and anti-inflammatory drugs. Concentration levels ranged between 5 ng/L and 2946 ng/L. Mixeduse pharmaceuticals were quantified in twelve samples of water resources and among these samples nine had a mixed overall fecal contamination. In the context of this large-scale study, it appeared difficult to determine precisely the factors impacting the occurrence of VPRs. VPRs were quantified in 20% of the tap water samples. Twelve VPRs were quantified, including ten compounds exclusively used in veterinary medicine and two mixed-use compounds. Concentration levels are inferior to 40 ng/L for all compounds, with the exception of the antibiotic florfenicol which was quantified at 159 ng/L and 211 ng/L. The population of Brittany may therefore be exposed to these contaminants through tap water. These observations should be put into perspective with the detection frequencies per compound which are all below 10% in both water resources and tap water.