Soil Behaviour of the Veterinary Drugs Lincomycin, Monensin, and Roxarsone and Their Toxicity on Environmental Organisms.

Lincomycin, monensin, and roxarsone are commonly used veterinary drugs. This study investigated their behaviours in different soils and their toxic effects on environmental organisms. Sorption and mobility analyses were performed to detect the migration capacity of drugs in soils. Toxic effects were evaluated by inhibition or acute toxicity tests on six organism species: algae, plants, daphnia, fish, earthworms and quails. The log Kd values (Freundlich model) of drugs were: lincomycin in laterite soil was 1.82; monensin in laterite soil was 2.76; and roxarsone in black soil was 1.29. The Rf value of lincomycin, roxarsone, monensin were 0.4995, 0.4493 and 0.8348 in laterite soil, and 0.5258, 0.5835 and 0.8033 in black soil, respectively. The EC50 for Scenedesmus obliquus, Arabidopsis thaliana, Daphnia magna and LC50/LD50 for Eisenia fetida, Danio rerio, and Coturnix coturnix were: 13.15 mg/L,32.18 mg/kg dry soil,292.6 mg/L,452.7 mg/L,5.74 g/kg dry soil and 103.9 mg/kg (roxarsone); 1.085 mg/L, 25 mg/kg dry soil, 21.1 mg/L, 4.76 mg/L, 0.346 g/kg dry soil and 672.8 mg/kg (monensin); 0.813 mg/L, 35.40 mg/kg dry soil, >400 mg/L, >2800 mg/L, >15 g/kg dry soil, >2000 mg/kg (lincomycin). These results showed that the environmental effects of veterinary drug residues should not be neglected, due to their mobility in environmental media and potential toxic effects on environmental organisms.