Contributing or lead author to several Priority Substance List Assessment Reports (Trichloroethylene,
Principal co-author for “A Protocol for the Derivation of Canadian Tissue Residue Guidelines for the Protection of Wildlife that Consume Aquatic Biota (1997)”
Lead author for “A Protocol for the Derivation of Water Quality Guidelines for the Protection of Aquatic Life – 2007”
Issues to consider in the derivation of water quality benchmarks for the protection of aquatic life.
ABSTRACT While water quality benchmarks for the protection of aquatic life have been in use in some jurisdictions for several decades (USA, Canada, several European countries), more and more countries are now setting up their own national water quality benchmark development programs. In doing so, they either adopt an existing method from another jurisdiction, update on an existing approach, or develop their own new derivation method. Each approach has its own advantages and disadvantages, and many issues have to be addressed when setting up a water quality benchmark development program or when deriving a water quality benchmark. Each of these tasks requires a special expertise. They may seem simple, but are complex in their details. The intention of this paper was to provide some guidance for this process of water quality benchmark development on the program level, for the derivation methodology development, and in the actual benchmark derivation step, as well as to point out some issues (notably the inclusion of adapted populations and cryptic species and points to consider in the use of the species sensitivity distribution approach) and future opportunities (an international data repository and international collaboration in water quality benchmark development).
Predicted no effect concentration (PNEC) derivation as a significant source of variability in environmental hazard assessments of chemicals in aquatic systems: An international analysis.
Integrated Environmental Assessment and Management
ABSTRACT Environmental hazard assessments for chemicals are performed to define an environmentally 'safe' level at which, theoretically, the chemical will not negatively affect any exposed biota. Despite this common goal, the methodologies in use are very diverse across different countries and jurisdictions. This becomes particularly obvious when international scientists work together on documents with global scope, e.g. in the WHO International Program on Chemical Safety. In this paper, we present a study that describes the extent of such variability and analyse the reasons that lead to different outcomes in deriving a 'safe level' (termed the Predicted No Effect Concentration (PNEC) throughout this paper). For this purpose, we chose five chemicals to represent well-known substances for which sufficient high-quality aquatic effects data were available: ethylene glycol, trichloroethylene, nonylphenol, hexachlorobenzene and copper. From these data, two datasets for each chemical were compiled: the full dataset, that contained all information from selected peer-review sources, and the base dataset, a sub-sample of the full set simulating limited data. Scientists from the EU, United States, Canada, Japan and Australia independently performed hazard assessments for each of these chemicals using the same datasets. Their reasoning for, e.g., key study selection, use of assessment factors or use of probabilistic methods was comprehensively documented. The observed variation in the PNECs for all chemicals was up to three orders of magnitude and this was not simply due to obvious factors such as the size of the dataset or the methodology used. Rather this was due to individual decisions of the assessors within the scope of the methodology used, especially key study selection, acute versus chronic definitions and size of assessment factors. Awareness of these factors, together with transparency of the decision-making process, would be necessary to minimise confusion and uncertainty related to different hazard assessment outcomes, particularly in international documents. The development of a 'guideline on transparency in decision-making' ensuring the decision-making process is science-based, understandable and transparent, may therefore be a promising way forward. Integr Environ Assess Manag © 2013 SETAC.
Water quality guidelines for chemicals: learning lessons to deliver meaningful environmental metrics.
Graham Merrington, Youn-Joo An, Eric P M Grist, Seung-Woo Jeong,Chuthamat Rattikansukha, Susan Roe, Uwe Schneider, Suthipong Sthiannopkao, Glenn W Suter, Rick Van Dam, Patrick Van Sprang, Ju-Ying Wang, Michael St J Warne, Paul T Yillia, Xiao-Wei Zhang, Kenneth M Y Leung
Environmental Science and Pollution Research
ABSTRACT Many jurisdictions around the globe have well-developed regulatory frameworks for the derivation and implementation of water quality guidelines (WQGs) or their equivalent (e.g. environmental quality standards, criteria, objectives or limits). However, a great many more still do not have such frameworks and are looking to introduce practical methods to manage chemical exposures in aquatic ecosystems. There is a potential opportunity for learning and sharing of data and information between experts from different jurisdictions in order to deliver efficient and effective methods to manage potential aquatic risks, including the considerable reduction in the need for aquatic toxicity testing and the rapid identification of common challenges. This paper reports the outputs of an international workshop with representatives from 14 countries held in Hong Kong in December 2011. The aim of the workshop and this paper was to identify 'good practice' in the development of WQGs to deliver to a range of environmental management goals. However, it is important to broaden this consideration to cover often overlooked facets of implementable WQGs, such as demonstrable field validation (i.e. does the WQG protect what it is supposed to?), fit for purpose of monitoring frameworks (often an on-going cost) and finally how are these monitoring data used to support management decisions in a manner that is transparent and understandable to stakeholders. It is clear that regulators and the regulated community have numerous pressures and constraints on their resources. Therefore, the final section of this paper addresses potential areas of collaboration and harmonisation. Such approaches could deliver a consistent foundation from which to assess potential chemical aquatic risks, including, for example, the adoption of bioavailability-based approaches for metals, whilst reducing administrative and technical burdens in jurisdictions.
Book Chapter: Water and Sediment EQS Derivation and Application
Reducing uncertainty in environmental risk assessment (ERA): clearly defining acute and chronic toxicity tests.
Integrated Environmental Assessment and Management 02/2009; 5(1):175-7.
Reducing uncertainty in environmental risk assessment (era): Clearly defining acute and chronic toxicity tests
Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 10/2002; 133(1-2):3-35.
ABSTRACT: Canadian Water Quality Guidelines (CWQG) are numerical or narrative limits that protect designated water uses. Development of CWQG is based on review of chromium's properties, uses, fate in the environment, ambient levels, accumulation in biota, and toxicity. Chromium's principal uses and entry into the environment include electroplating, production of paints and pigments, tanning, wood preservation, chromium chemicals production, metal smelting, and pulp and paper production. Concentrations of chromium in Canada range between 1 and 545,000 ng·m?3 in air, 0.001 and 0.165 mg·L?1 in water, nondetectable and 31,000 mg·kg?1 in sediments, 10 and 5000 mg·kg?1 in soils, 0.006 and 18 mg·kg?1 in plants, and 0.03 and 1.6 mg·kg?1 in animals. In nature, trivalent chromium sorbs to various ligands and forms insoluble entities becoming unavailable for uptake by biota. Hexavalent chromium forms many soluble salts that can enter body membranes and induce a toxic response. Estimates of toxicity of hexavalent chromium to aquatic life range from 0.0006 mg·L?1 (reduction in algal growth) to 1000 mg·L?1 (decrease in rest time of Chironomus tentans). For trivalent chromium the toxicity ranges from 0.002 mg·L?1 (reduction in filtering rate of Perna perna) to 937 mg·L?1 (48-h LC50 of Asellus aquaticus). Plants are affected by the concentrations of hexavalent chromium ranging from 0.16 mg·L?1 (growth reduction in lettuce) to 75 mg·L?1 (no effects in sweet orange). For trivalent chromium the toxicity ranges between 0.104 mg·L?1 (reduction in root growth of oats) and 50 mg·L?1 (stunted growth of corn and tomato). Terrestrial animals such as the beagle dog can be affected by concentrations exceeding 62.7 mg·L?1 (Cr VI). Mice can tolerate 100 mg·L?1 of hexavalent chromium. Trivalent chromium has adverse effects on rats and mice at 28.0 mg·L?1. For freshwater life, guidelines of 0.001 (Cr VI; full) and 0.008 (Cr III; interim) mg·L?1 are recommended. For marine life, guidelines of 0.001 (Cr VI; draft) and 0.05 (Cr III; interim) mg·L?1 are recommended. Irrigation guidelines are set at 0.008 (Cr VI) and 0.005 (Cr III). A guideline of 0.05 mg·L?1 is recommended for drinking and livestock waters. © 1997 by John Wiley & Sons, Inc. Environ Toxicol Water Qual 12: 123–183, 1997
Environmental Toxicology and Water Quality 12/1998; 12(2):123 - 183.
Article: Screening assay for dioxin-like compounds based on competitive binding to the murine hepatic Ah receptor. 1. Assay development.
Environmental Science and Technology 10/1995; 29(10):2595-602.
Additive binding of polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin to the murine hepatic Ah receptor.
ABSTRACT: Fixed aliquots of both radiolabeled [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and hepatic Ah receptor from C57BL/6J mice were incubated competitively at 4, 23, and 30 degrees C with mixtures of 2,3,7,8-TCDD and several polychlorinated biphenyls (PCBs). The production of the radiolabeled receptor-ligand complex changed if the ligands were added sequentially, demonstrating that the competition between PCBs and TCDD for the Ah receptor in vitro is principally a kinetic rather than an equilibrium phenomenon and is irreversible on the time scale of our in vitro experiments. Examination of previous reports on the ability of TCDD, PCBs, and their mixtures to induce cleft palate in fetal mice suggests that the potency of receptor-ligand complexes is ligand-dependent. Receptor occupancy is not a sufficient condition for toxicity, and protection by one ligand against the toxic effect of a second, more potent one is only possible when a significant fraction of receptors is occupied.
Toxicology and Applied Pharmacology 01/1995; 129(2):243-51.
N BUNCE, U SCHNEIDER
ABSTRACT: Estimates have been obtained for all half-lives of several chlorinated aliphatic pollutants in the Canadian troposphere. The rates of reaction are strongly dependent on the magnitude of the second-order rate constant for reaction of the pollutant with OH, and on the intensity of solar radiation , which is determined both by season and geographical location. Of the pollutants studied, trichloroethylene has the shortest half-life of 2–5 days in summer, depending on location. Dichloromethane, 1,2-dichloroethane and tetrachloroethylene are each about one order of magnitude longer lived than trichloroethylene; 1,1,1-trichloroethane and 1,1,2,2-tetrachloroethane are about two orders of magnitude longer lived than trichloroethylene. Under urban conditions, high rates of oxidation, and hence short half-lives, are favoured by high tropospheric concentrations of ozone and low concentrations of NO2. With the exception of 1,1,1-trichloroethane, none of these substances is predicted to pose a significants threat to stratospheric ozone.
Journal of Photochemistry and Photobiology A-chemistry - J PHOTOCHEM PHOTOBIOL A-CHEM. 01/1994; 81(2):93-101.
Chlorinated trans stilbenes: Competitive binding to the ah receptor, Induction of cytochrome p?450 monooxygenase activity and partial 2,3,7,8?TCDD antagonism
ABSTRACT: Chlorinated trans stilbenes bind with high affinity to the cytosolic Ah receptor from Wistar rat liver. The EC50 values for competition with [H]?2,3,7,8?tetrachlorodibenzo?p?dioxin (TCDD) cover a range from 10–400 nM, but with no apparent relationship between molecular structure and binding activity. These compounds induce monooxygenase enzyme activity in rat hepatoma H?4?II E cells in culture only weakly, again with no apparent dependence on molecular structure, and the weakest enzyme inducers act as antagonists for the induction of these enzymes by TCDD. In vivo administration of 3,3’,4,4'?tetrachloro?tans?stilbene in the rat leads to decreased Ah receptor levels.
Toxicological & Environmental Chemistry. 01/1990; 28(4):217-229.
ABSTRACT: An assay for mixtures of PCDD-like compounds is being developed, based on the competitive binding of the mixture and a fixed aliquot of radiolabelled [3H]-TCDD towards the mouse hepatic Ah receptor protein. The results are expressed in terms of the concentration of unlabelled TCDD which produces the same response as the mixture. Preliminary experiments indicate that mixtures behave additively in this assay.
With respect to water quality benchmarks, patient unfortunately, advice different terminology is being used across jurisdictions in Canada and around the world, often with conflicting definitions and interpretations. Terminology may even differ within the same country. Terms like guideline, criterion, standard, objective, limit, threshold, trigger value, and benchmark are all used inconsistently, and sometimes interchangeably. What is a “guideline” in one jurisdiction, is a “criterion” in another, and a “standard” in a third. However, in many but not all jurisdictions, the term “water quality guideline” (e.g., Canada [national], Autralia, New Zealand, etc.) or “water quality criterion” (e.g., USA) is given to a voluntary guidance value, “water quality standard” is used for a legally-enforceable benchmark (e.g., Canada, USA), while the term “water quality objective” is applied when technological or socio-economic aspects are incorporated (e.g., Canada [national]). However, there are many exceptions, for example within Canada, the Province of Ontario had published its “Provincial Water Quality Objectives”, which are science-based and equivalent in legal standing to the national “Canadian Water Quality Guidelines”, i.e., voluntary guidance benchmarks. Other jurisdictions may identify legally-enforceable values as “water quality criteria”. International harmonization in terminology would be ideal and practical, but is also likely unobtainable.
Various Forms of Water Quality Benchmarks
A water quality benchmark is generally a threshold level(s) and guidance value(s) which aims to approximate the level where there are no observable effects (or accepted effects) to aquatic life. Such a benchmark can either be quite simple (e.g., a single value), or be more complex (e.g., a range or values), or quite extensive (e.g., equations, tables, or matrices). It can be a numeric value(s), a narrative statement, or a combination of both. The former option is used mostly for chemical substances, while the latter is used often for environmental parameters (such as pH, temperature, turbidity, water hardness, etc.).
Generic / National versus Local / Site-Specific Water Quality Benchmarks
It is recognised that the concentration of a substance in the ambient environment is the result of natural factors, human actions, or a combination of both, and that these concentrations change over time and space. Both the natural and anthropogenically caused variations in concentrations over time can be quick (i.e., over hours or days) or slow (i.e., seasonal, decades, centuries), and spatial differences can occur abruptly over very short distances (intercept of two different surface geologies, upstream versus downstream of a significant point source at a river, etc.) or gradual over large areas (along a river with diffuse sources, estuaries, near shore versus open ocean). With respect to naturally occurring substances, it is important to distinguish between the portion of the concentration that is due only to natural causes (i.e., the natural background concentration) and the portion of the concentration that is due, at least in part, to anthropogenic causes (sometimes referred to as the ambient concentration). However, quantifying these two portions reliably is often challenging. A water quality benchmark designed to apply over a large geographic area (e.g., a national water quality benchmark) is derived considering all acceptable and applicable toxicological data from a variety of toxicological studies (i.e., including organisms from different aquatic ecosystems and regions, and experimental exposure conditions resembling different geological backgrounds). As the natural background concentration of naturally occurring substances is a very site-specific matter, it often cannot be adequately addressed by such a (national) benchmark. It regularly happens that the recommended national benchmark value for such a substance falls below the natural background concentration (or outside of natural conditions) of a particular site of interest. This happens for example with many national benchmarks for metals when applied to mineral-rich areas (as in the vicinity of mining sites). This fact does not invalidate the national benchmark or its derivation process, but it shows the need to understand this derivation process and to know how to properly apply benchmark values. It generally leads to the derivation of site-relevant values (i.e., site-specific water quality benchmarks) to better reflect the adapted local ecosystem.
This approach to develop a site-specific water quality benchmark is based on the assumption that the biological community present at a site has adapted to the local conditions, including a naturally elevated level of the substance of concern. It does, however, not imply that the adapted community may be able to adjust to an additional, anthropogenically created exposure to this substance without showing negative effects. This can only be determined with appropriately designed site-specific toxicity studies and can generally not be deduced from generic, non-site-specific studies.