title: Testing an application of a biotic ligand model to predict acute toxicity of metal mixtures to rainbow trout.
abstract: The authors tested the applicability of a previously developed biotic ligand model (BLM) to predict acute toxicity of single metals and metal mixtures (cadmium, lead, and zinc) to rainbow trout fry (Oncorhynchus mykiss) from a single available dataset. The BLM used in the present study hypothesizes that metals inhibit an essential cation (calcium) and organisms die as a result of its deficiency, leading to an assumption that the proportion of metal-binding ligand (f) is responsible for the toxic effects of metals on the survival of rainbow trout. The f value is a function of free-ion concentrations of metals computed by a chemical speciation model, and the function has affinity constants as model parameters. First, the survival effects of single metals were statistically modeled separately (i.e., f-survival relationship) by using the generalized linear mixed model with binomial distribution. The modeled responses of survival rates to f overlapped reasonably irrespective of metals tested, supporting the theoretical prediction from the BLM that f-survival relationships are comparable regardless of metal species. The authors thus developed the generalized linear mixed model based on all data pooled across the single-metal tests. The best-fitted model well predicted the survival responses observed in mixture tests (r = 0.97), providing support for the applicability of the BLM to predict effects of metal mixtures.
authors.affiliation: Department of Civil Engineering, Tokyo Institute of Technology, Tokyo, Japan; Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Masashi
authors.initials: M
authors.lastname: Kamo
authors.forename: Wataru
authors.initials: W
authors.lastname: Naito
mesh_terms: D000465:Algorithms; D000818:Animals; D002104:Cadmium / Q000633:toxicity; D002118:Calcium / Q000378:metabolism; D006812:Humic Substances; D007854:Lead / Q000633:toxicity; D008024:Ligands; D016014:Linear Models; D008670:Metals / Q000633:toxicity*; D008954:Models, Biological; D017686:Oncorhynchus mykiss / Q000502:physiology*; D016019:Survival Analysis; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015032:Zinc / Q000633:toxicity
chemical_list: D006812:Humic Substances; D008024:Ligands; D008670:Metals; D014874:Water Pollutants, Chemical; D002104:Cadmium; D007854:Lead; D015032:Zinc; D002118:Calcium
keywords: Chemical mixtures; Ecological risk assessment; Metal bioavailability; Salmonids; Windermere humic aqueous model