The introduction of drug residues into the food chain and their presence in drinking water has been recently investigated. The aim of this work was to monitor the presence of 19 active drugs in water samples collected from milking parlors of dairy farms located in Galicia (northwest Spain), one of the main Spanish milking areas. Overall, 65% of the samples tested positive for at least one of the compounds analyzed. A total of 12 drugs were measured, with concentrations ranging between 17 and 3,941 ng/L. Considering that a mixture of compounds may contribute to the overall effect of each compound and might increase or reduce its toxicity, it should be noted that 29% of the samples tested contained more than one pharmaceutical. To date, the effects of the continuous consumption of these mixtures of drugs in water or milk are unknown; however, antimicrobials may affect the human gut microbiota or have toxic effects in sensitive individuals.

Nowadays, food production systems play a relevant role as the steady increase of global population and food demand. The water-energy-food (WEF) nexus is a suitable approach to tackle resources management associated with these three pillars recognizing synergies and trade-offs. Different approaches have been used in the literature to measure the WEF nexus, being material flow analysis (MFA) and life cycle assessment (LCA), two of the most proven methodologies. The MFA approach is based on the amount of resources consumed, while using the LCA perspective considers all flows of the system (LCA footprints approach) or considering only the flows associated with water, energy, and food pillars as the inventory data (WEF-LCA approach). This manuscript compares the three mentioned approaches to identify their strengths and weaknesses. To do this, a sample of 100 Spanish dairy farms is analysed, where a single WEF nexus index (WEFni) is obtained using Data Envelopment Analysis. Results show that only four farms achieved a WEFni equal to 100 in all approaches, while the main difference between them is the number and type of resources considered for calculating the WEF nexus, which could imply a partial identification of hotspots of food systems.