Antibiotics residues in pig slurry and manure and its environmental contamination potential : a meta-analysis

Abstract

Livestock excrements are used as natural fertilizer, in the form of manure or slurry, to provide nutrients and organic matter to arable soils. However, it is potentially contaminated with antibiotics residues, used in livestock farming to prevent diseases (and thus animal losses), as well as to increase animals’ body weight. This poses a contamination risk to surrounding environments. Therefore, we quantitatively evaluated data from 57 peer-reviewed articles published over the past 20 years to generate an overview of antibiotics residues in manure, slurry, soils, plants, and water. Our results revealed that pig manure and slurry, mostly from European countries, contained fluoroquinolones, sulfonamides, and tetracyclines. Furthermore, antibiotics used in animal husbandry are found to contaminate surrounding environments, exceeding the proposed EU threshold value for maximal environmental contamination by veterinary antibiotics in soil in many countries. In soil samples, the highest contents of tetracyclines and sulfonamides were detected in the UK (41 ± 18 μg/kg and 300 ± 10 μg/kg, respectively) and in Austria (370 μg/kg) for fluoroquinolones. In water environments, antibiotics contents were detected in low amounts in most countries (< 2 μg/L), with the highest content of fluoroquinolones and tetracyclines detected in the USA (3 ± 0.7 μg/L and 1.3 ± 0.6 μg/L, respectively) and of sulfonamides in the USA and Germany (0.3 ± 0.8 μg/L and 0.2 ± 2 μg/L, respectively). In plants, an accumulation of tetracyclines and sulfonamides was found in China, Germany, and Spain (> 50 μg/kg). However, no significant specificity of these antibiotics residues to country or continent could be observed. It is urgent that the use of veterinary antibiotics be significantly reduced in order to diminish their residues in slurry, and thus their contamination potential to the surrounding environments.