title: Comparing three approaches in extending biotic ligand models to predict the toxicity of binary metal mixtures (Cu-Ni, Cu-Zn and Cu-Ag) to lettuce (Lactuca sativa L.).
abstract: Metals are always found in the environment as mixtures rather than as solitary elements. However, effect models such as biotic ligand models (BLMs) are usually derived for toxicity prediction of single metals. Our study aimed at predicting mixture toxicity of Cu-Ni, Cu-Zn and Cu-Ag combinations to lettuce (Lactucasativa L.) by combining BLMs with three toxicity indexes: the toxic unit, the overall amounts of metal ions bound to the biotic ligands and the toxic equivalency factor. The accumulation of metal ions at the biotic ligands was used to determine the toxic potency of metals alone or in combination. On the basis of parameters derived from toxicity assessment of individual metals, these three extended BLMs appeared to be all acceptable (p<0.0001) in assessing toxicity of diverse metal mixtures. The BLM-based approaches integrated competition between metal ions in assessing mixture toxicity and showed different predictive ability for each metal combination. The outcome of modeling suggested that the combined toxicity depends on the specific components of the metal mixtures. The best developed models assist in identifying the type of underlying toxic mechanisms of diverse metal mixtures in terrestrial plants.
authors.affiliation: Institute of Environmental Sciences (CML), Leiden University, 2300 RA Leiden, The Netherlands. Electronic address: liu@cml.leidenuniv.nl.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Institute of Environmental Sciences (CML), Leiden University, 2300 RA Leiden, The Netherlands.
authors.forename: Martina G
authors.initials: MG
authors.lastname: Vijver
authors.affiliation: Institute of Environmental Sciences (CML), Leiden University, 2300 RA Leiden, The Netherlands; National Institute of Public Health and the Environment (RIVM), Center for Safety of Substances and Products, 3720 BA Bilthoven, The Netherlands.
authors.forename: Willie J G M
authors.initials: WJ
authors.lastname: Peijnenburg
mesh_terms: D003300:Copper / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D054750:Ecotoxicology / Q000379:methods*; D004785:Environmental Pollutants / Q000633:toxicity*; D006863:Hydrogen-Ion Concentration; D018545:Lactuca / Q000187:drug effects*; D008024:Ligands; D019216:Metals, Heavy / Q000633:toxicity*; D008954:Models, Biological; D009532:Nickel / Q000633:toxicity; D012834:Silver / Q000633:toxicity; D015032:Zinc / Q000633:toxicity
chemical_list: D004785:Environmental Pollutants; D008024:Ligands; D019216:Metals, Heavy; D012834:Silver; D003300:Copper; D009532:Nickel; D015032:Zinc
keywords: Biotic ligand models; Lettuce; Metal mixtures; Toxicity; Toxicity index