title: Determination of water quality standards for chemical mixtures: extension of a methodology developed for herbicides to a group of insecticides and a group of pharmaceuticals.
abstract: Monitoring surveys throughout America and Europe have demonstrated the widespread presence of organic synthetic substances such as pesticides and pharmaceuticals in surface water. To avoid deleterious effects on the aquatic system, many countries determine water quality criteria for pesticides. For each substance, the comparison of the concentration measured in water with its criterion gives an indication of the pressure this substance put on the aquatic system. However, in the environment, aquatic organisms are not only exposed to single pesticides but typically to mixtures of these substances. It is therefore of particular importance to take mixtures into account when defining water quality criteria, which is rarely done yet. We recently developed a method to define consistent and comparable water quality criteria for mixtures of herbicides having a similar mode of action. These criteria are calculated based on species sensitivity curves; the method assumes that these curves are parallel for substances having similar mode of action. The aim of this study was to apply our method to six organophosphates (insecticides) and to three β-blockers (pharmaceuticals), other groups of compounds commonly detected in surface water. We found some evidence that the developed methodology gives consistent results for these groups too. The hypothesis of parallelism was accepted in 2/3 (β-blockers) and 2/6 of the cases (organophosphates) for both species sensitivity curves based on effect concentrations 50% and on no-observed effect concentrations. The use of water quality criteria for mixture is illustrated by two case studies, which show the importance of taking mixtures into account in water quality legislation.
authors.affiliation: IPTEH, Faculty of Earth Sciences and Environment, University of Lausanne, CH-1015 Lausanne, Switzerland. nathalie.chevre@unil.ch
authors.forename: Nathalie
authors.initials: N
authors.lastname: Chèvre
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Maillard
authors.forename: Christian
authors.initials: C
authors.lastname: Loepfe
authors.forename: Kristin
authors.initials: K
authors.lastname: Becker-van Slooten
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000032:analysis* / Q000592:standards / Q000633:toxicity; D000569:Americas; D000818:Animals; D059001:Aquatic Organisms / Q000187:drug effects; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods* / Q000592:standards; D005060:Europe; D005399:Fishes; D005618:Fresh Water / Q000032:analysis / Q000737:chemistry; D006540:Herbicides / Q000032:analysis* / Q000592:standards / Q000633:toxicity; D007306:Insecticides / Q000032:analysis* / Q000592:standards / Q000633:toxicity; D007448:Invertebrates / Q000187:drug effects; D058086:Microalgae / Q000187:drug effects; D018570:Risk Assessment; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000592:standards / Q000633:toxicity; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data; D014881:Water Supply / Q000032:analysis / Q000706:statistics & numerical data
chemical_list: D000319:Adrenergic beta-Antagonists; D006540:Herbicides; D007306:Insecticides; D014874:Water Pollutants, Chemical