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Abstract: Monensin and lasalocid are carboxylic ionophore antibiotics used as coccidiostats in the poultry industry. They enter the environment with the use of broiler excrements for manure. As ionophores, they affect the transport of cations across membranes. We studied the bioaccumulation of cadmium and lead in woodlice when concurrently exposed to either monensin or lasalocid. At monensin concentrations (1.8mg/kg food) comparable to those that could be expected in nature, there was no effect on cadmium accumulation. At 100 times higher ionophore concentrations the presence of monensin or lasalocid resulted in significantly lower cadmium or lead content in woodlice. However, under natural conditions such high levels of ionophores are unlikely. The use of ionophore-contaminated manure in areas where metal pollution is probably does not result in any increased risk to soil invertebrates. [Copyright &y& Elsevier]

Abstract: Monensin is a carboxylic polyether ionophore used in the poultry industry as a coccidiostat. It enters the environment via manure from broiler farms. In spite of its potential presence in the environment, information concerning monensin residues in manure and soil and its toxicity to soil organisms are insufficient. In the present study, two beneficial soil invertebrate species, earthworms (Eisenia andrei) and woodlice (Porcellio scaber), were used to assess the toxicity of monensin. Animals were exposed to a range of monensin concentrations via soil or food. Earthworm reproduction was found to be the most susceptible endpoint (NOEC=3.5mgkg−1 dry soil; EC50 =12.7mgkg−1 dry soil), while no adverse effects were recorded in isopods (NOEC⩾849mgkg−1 dry soil, NOEC⩾357mgkg−1 dry food). The obtained toxicity data were compared with potential concentrations of monensin in soil. In view of this, manure from broiler chickens treated with monensin at a poultry farm was sampled. According to monensin and nitrogen concentrations in the chicken manure and the degradation time of monensin, the predicted environmental concentration (PEC) was calculated. PEC of monensin is around 0.013mgkg−1 soil if manure is used after 3months of composting and 0.05mgkg−1 soil if used without storage. Data for earthworm reproduction was used to estimate the predicted no-effect concentration (PNEC). If fresh chicken manure is applied to terrestrial ecosystems, the risk quotient (PEC/PNEC ratio) is above 1, which indicates that monensin might pose an environmental risk under certain conditions. To prevent this, it is strongly recommended to compost chicken manure for several months before using it as fertiliser. [Copyright &y& Elsevier]