Evaluación de la presencia de residuos de fármacos en aguas de pozos y explotaciones lecheras

Resumo

The continued release of pharmaceuticals in the environment, mainly through discharge of sewage treatment plants and application of manure as fertilizer, has led to the presence of these active substances in the aquatic environment. In the last decade, numerous works brought out the entrance and presence of these substances in the aquatic cycle all over the world. The lack of data of the presence of these types of substances in Galician water used in animal production, and in privately used water, highlights the need to investigate the situation in Galicia. Therefore, the aim of this thesis is to evaluate the presence of residues of pharmacological substances in water used in the production of milk and in private wells in the Galician community, to be able to carry out an estimation of the risk derived from the consumption of these waters. The selected analytical technique was HPLC-MS/MS because it allows the simultaneous identification and quantification in a sensitive, selective and rapid way, a great number of substances from different therapeutic groups. A total of 292 samples were taken, of which, 52 were from milking parlours, 122 from cows drinking troughs and 118 from private wells. The 39% of the analysed samples were positive for at least one of the 23 investigated drugs, specifically, more than one compound was detected in 29% of the samples obtained from milking parlours, in 13% of the drinking troughs and in 16% of the well samples. Independently of the origin of the water, tap water or groundwater, the drugs detected more frequently and at a higher concentration were those belonging to the group of antimicrobials, followed by those of the group coccidiostats. The climatic conditions, specifically accumulated rainfall, influenced the frequency of detection of the active substances in groundwater. Likewise, in the province of Lugo, more positive samples were observed in the areas with higher number of heads of cattle. The waters from the cleaning of the milk parlours showed low levels of pharmaceuticals, which, due to the dilution with milk would not be a possible public health problem. This work reveals that both humans and dairy cows unexpectedly consumed drugs at low concentrations (ng/L) and sometimes from different therapeutic groups. Although more studies are needed, the continued consumption of antibiotics may lead to the modification of gut microbiota, reactions in sensitive people with allergies, bacterial development with resistant genes, as well as interacting with other drugs administered or taken. In the case of humans, a potential risk for both children and adults derived from the presence of antimicrobials in groundwater, specifically sulfapyridine and sulfamethizole, was observed