The Exposure Level And Ecological Risk Assessment Of Typical Veterrinary Medicines In Livestock Husbandary

Veterinary medicines are widely used in breeding industry (livestock breeding and aquaculture). As a result, approximately30-90%ingested antibiotic doses and their metabolites were excreted together by animals’urine and feces. More importantly, significant amounts of veterinary medicines and their metabolites were disseminated to environment through fertilization and irrigation. Subsequently, veterinary medicines were introduced into different systems, particularly soil-vegetable systems and soil-animal systems. Veterinary medicines can be uptaked by plant roots and animals that have been exposured to the contaminated environment, then translocated to crops and animals, which may bring hazard to human health. Sulfonamides, estrogens, tetracyclines and fluoroquinolones are most commonly used veterinary medicines, which were selected as representatives of veterinary medicines in this study. The main results are as follows:1). A method was established for the simultaneous analysis of sulfadiazine, sulfamerazine, sulfathiazole, sulfamethazine, sulfadimethazine, sulfamethoxazole,17a-estradiol,17β-estradiol, estrone, estriol,17a-ethinyl-estradiol and hexestrol in this study. A single-step sample preparation by solid-phase extraction (SPE) on Oasis HLB cartridges was used to concentrate all analytes simultaneously. Soil sample was firstly extracted by accelerated solvent extraction (ASE), and then purified and concentrated by Oasis HLB cartridges. The optimized method used a mixture of methanol and acetone (1:1, v/v) as solvent for the extraction at80℃and1500psi during five min. Determination was carried out by high-performance liquid chromatography tandem mass spectrometry. The recoveries of sulfonamides and estrogens for water and soil were84.8%～103.6%and58.2%～80.0%respectively. Method detection limits of sulfonamides and estrogens ranged from0.11to2.14ng/L for water samples and0.01to0.21ng/g for soils. A method was optimized for the simultaneous analysis of sulfonamides in manure, meat, vegetable and feed. The recovery of sulfonamides were44.3%～96.1%. Method detection limits of sulfonamides ranged from0.02to0.23ng/g for other matries.A method was optimized for the simultaneous analysis of tetracycline, oxytetracycline, chlorotetracycline, norfloxacin, ciprofloxacin, enrofloxacin, ofloxacin in this study. The recoveries of tetracyclines and fluoroquinolones for water and other matries were91.3%～97.4%and64.0%～82.8%respectively. Method detection limits of tetracyclines and fluoroquinolones ranged from0.8to1.2ng/L for water samples and0.1to0.4ng/g for other matries. All determination was carried out by high-performance liquid chromatography tandem mass spectrometry.2). Analysis of exposure levels of veterinary medicines in different typical farms. A swine farm in Suqian of Jiangsu Province, a typical scale fishpond in Tangshan County of Nanjing, Jiangsu Province and a typical dairy farm in Jiangning County of Nanjing, Jiangsu province were selected as the research objects. Water, soil, manure, sediment, animal and plant samples in the farms were collected and analyzed.The main veterinary medicine detected in Suqian swine farm was sulfmethazine, the highest concentration of which was214.8ng/g in manure. The concentration in waters and sediments were42.4-75.5ng/L and7.1-34.4ng/g. The adsorption capacity was weak, calculated distribution coefficient from water to sediment was only1.9-6.0L/Kg. Different kinds of fish had a certain enrichment of sulfmethazine. The main veterinary medicines detected in Jiangning dairy farm was oxytetracycline, which had the highest detectable concentration of73.2ng/g for manure. Oxytetracycline had strong adsorption capacity in sediment. The calculated distribution coefficient from water to sediment was only197-657.1L/Kg. The main veterinary medicines detected in Jiangning fishpond were norfloxacin, enrofloxacin and ofloxacin. The highest detectable concentration of enrofloxacin was between107.7-504.0ng/g in sediments. Three types of drugs detected had very strong adsorption capacity in sediment. In addition, enrofloxacin and ofloxacin also could be detected in the fish tissue, the concentrations detected in carps and breams were 1360-4021.9and408.7-462.6times of the concentrations detected in sediments. Crap had greater enrichment capacity than bream.3).The exposure concentration prediction and ecological risk assessment of typical veterinary medicines. Sulfadimidine and oxytetracycline were selected to conduct the exposure concentration prediction and ecological risk assessment, due to their general application. The EU classic exposure prediction model was used to predict the concentration of sulfadimidine and oxytetracycline in the soil and surface water in typical farms. The predicted exposure concentrations of sulfadimidine were0.194mg/kg and5.88ng/L. The predicted exposure concentrations of oxytetracycline were0.024mg/kg and0.017ng/L. Meanwhile, The European veterinary medicine ecological risk assessment technology was used to predict the ecological risk of sulfadimidine and oxytetracycline. Preliminary assessment results show that sulfathaine had greater ecological risk to aquatic organisams, so the aquatic ecological risk value calculated exceeded the standard value of1. Qxytetracycline had greater ecological risk to terresrial organisams, terresrial ecological risk value calculated was greater than the standard value of1.