Occurrence and environmental behavior of residues of veterinary antibiotics

Author(s)

Rafael Marques Pereira Leal

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB)
• Defense date: 2012-05-28

Examining board members

Jussara Borges Regitano; Severino Matias de Alencar; Robson Rólland Monticelli Barizon; Douglas Emygdio de Faria; Jurandir Rodrigues de Souza

• Advisor: Jussara Borges Regitano

Abstract

Many antibiotics used for veterinary purposes use are not fully metabolized in the animal body, resulting in the presence of residues in a wide range of environmental matrices such as animal manures, soils and sediments. The occurrence of these residues in the environment can favour microorganisms resistance to antibiotic agents, cause toxicological problems to certain organisms and, besides, also interfere in the biogeochemical cycles mediated by microorganisms. Despite the high use of veterinary antibiotics in Brazil, so far there are no data regarding the occurrence and environmental behavior of the main compounds currently in use in the country. This work represented a first investigation on the occurrence of an important class of antibiotics, the fluoroquinolones, in environmental samples (poultry litter and soil), also investigating aspects of the environmental behavior of fluoroquinolones and sulfonamides in these matrices through sorption experiments. Overseas, dissipation and sorption behavior of fluoroquinolones were studied for New Zealand soils. For the quantification of fluoroquinolone residues in poultry litter and soil samples, an analytical methodology was adapted and validated. Overall, the results demonstrated the occurrence of fluoroquinolone residues in concentrations (mg kg-1 for poultry litter and g kg-1 for soil) comparable to those found elsewhere (China, Austria and Turkey), a high sorption potential of fluoroquinolones to soils (Kd from 544 to 1,277,874 L kg-1), higher than the reference values for soil (Kd = 260 to 5,012 L kg-1), and much higher than for poultry litter (Kd 65 L kg-1), showing that the transport of these molecules will only occur in association with the soil particles, possibly reaching superficial water sources. In the case of sulfonamides, sorption coefficients were relatively low (Kd = 0.7 to 70.1 L kg-1), showing their leaching potential in the soil profile. Texture and cation exchange capacity greatly affected the sorption of sulfonamides and fluoroquinolones to soils, emphasizing the importance of ion exchange processes on the sorption of antibiotics in tropical soils. In New Zealand soils, with a higher buffer capacity, sorption of fluoroquinolones was also high, but lower than to Brazilian soils, and the addition of poultry litter to soil reduced the sorption potential of these compounds. Fluoroquinolones dissipation varied considerably ((DT50 = 16 to >70 days), being faster in sub-surface samples despite its lower biological activity. Antibiotics are routinely used in animal production, representing a potential source of pollution to the environment that has been largely ignored and should be further investigated in Brazil (AU)

• FAPESP's process: 07/08425-0 - Environmental occurrence and behavior of veterinary antibiotics residues
• Grantee: Rafael Marques Pereira Leal
• Support Opportunities: Scholarships in Brazil - Doctorate