The Variation in Slope of Concentration–Effect Relationships

Smit, Mathijs G.D.; Hendriks, A. Jan; Schobben, J.H.M.; Karman, C.C.; Schobben, H.P.M.

doi:10.1006/eesa.2000.1983

Cited by 44 publications

(38 citation statements)

References 25 publications

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“…When constructing a SSD, the choice of the distribution function to fit of the data and describe the distribution is arbitrary and usually based on best-fit results [14,15]. Log-logistic and lognormal distributions often are used for toxic stressors because effect concentrations can differ between species by several orders of magnitude [16].…”

Section: Derivation Of the Ssdmentioning

confidence: 99%

Development and application of a species sensitivity distribution for temperature‐induced mortality in the aquatic environment

Vries¹,

Tamis²,

Murk

et al. 2008

Enviro Toxic and Chemistry

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Current European legislation has static water quality objectives for temperature effects, based on the most sensitive species. In the present study a species sensitivity distribution (SSD) for elevated temperatures is developed on the basis of temperature sensitivity data (mortality) of 50 aquatic species. The SSD applies to risk assessment of heat discharges that are localized in space or time. As collected median lethal temperatures (LT50 values) for different species depend on the acclimation temperature, the SSD is also a function of the acclimation temperature. Data from a thermal discharge in The Netherlands are used to show the applicability of the developed SSD in environmental risk assessment. Although restrictions exist in the application of the developed SSD, it is concluded that the SSD approach can be applied to assess the effects of elevated temperature. Application of the concept of SSD to temperature changes allows harmonization of environmental risk assessment for stressors in the aquatic environment. When a synchronization of the assessment methods is achieved, the steps to integration of risks from toxic and nontoxic stressors can be made.

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Section: Derivation Of the Ssdmentioning

confidence: 99%

Development and application of a species sensitivity distribution for temperature‐induced mortality in the aquatic environment

Vries¹,

Tamis²,

Murk

et al. 2008

Enviro Toxic and Chemistry

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“…In toxicity testing of single species, common slopes of concentration-response curves have often been assumed for compounds with the same mode of action although no evidence has been found to confirm this assumption (58). As a pragmatic solution to this dilemma, three options were explored for obtaining parallel SSD.…”

Section: Resultsmentioning

confidence: 99%

Including Mixtures in the Determination of Water Quality Criteria for Herbicides in Surface Water

Chèvre

Loepfe

Singer

et al. 2005

Environ. Sci. Technol.

119

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Monitoring programs throughout America and Europe have demonstrated the common occurrence of herbicides in surface water. Nevertheless, mixtures are rarely taken into account in water quality regulation. Taking mixtures into account is only feasible if the water quality criteria (WQC) of the single compounds are derived by a common and consistent methodology, which overcomes differences in data quality without settling on the lowest common denominator but making best use of all available data. In this paper, we present a method of defining a risk quotient for mixtures of herbicides with a similar mode of action (RQ m ). Consistent and comparable WQC are defined for single herbicides as a basis for the calculation of the RQ m . Derived from the concentration addition model, the RQ m can be expressed as the sum of the ratios of the measured environmental concentration and the WQC for each herbicide. The RQ m should be less than one to ensure an acceptable risk to aquatic life. This approach has the advantage of being easy to calculate and communicate, and is proposed as a replacement for the current limit of 0.1 µg/L for herbicides in Switzerland. We illustrate the proposed approach on the example of five commonly applied herbicides (atrazine, simazine, terbuthylazine, isoproturon, and diuron). Their risk profile, i.e., the RQ m as a function of time for one exemplary river, clearly shows that the single compounds rarely exceeded their individual WQC. However, the contribution of peaks of different seasonally applied herbicides, whose application periods partially overlap, together with the continuously emitted herbicides from nonagricultural use, results in the exceedance of the RQ m threshold value of one upon several occasions. IntroductionPesticides, including herbicides, differ from most industrial organic compounds in being introduced into the environment with the explicit intention of exerting effects on one or more target organisms. Unfortunately, they do not exert their toxic action only where they are applied, but can, through persistence and transport, reach other compartments of the ecosystem. Monitoring programs throughout North America and Europe have demonstrated the widespread presence of pesticides in various freshwater bodies (1-6). Over the past decade, as public concern has focused on the possible impacts of pesticides on the environment, several European and North American countries (7)(8)(9)(10)(11)(12)(13)(14) have defined specific water quality criteria (WQC) for each pesticide in surface waters. Within the EU, these WQC are often equivalent to the predicted no-effect concentration (PNEC), which aims to ensure the overall protection of aquatic life (9,12,14). This parameter is usually estimated by finding the lowest reliable aquatic effect concentration and applying a safety factor to account for various uncertainties, such as interspecies differences in sensitivity, acute-to-chronic ratios, and laboratory-to-field extrapolations (for review see refs 15-17). The drawback of this approach is...

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“…The slopes of the concentration‐response curves range between 2.7 to 20.9. Although the mode of toxic action is often suggested as an explanation for different slopes of concentration‐effect curves, Smit et al found no distinction between the slope values of narcotic substances and substances with a specific mode of action [25]. Consequently, this topic is not taken into further considerations.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic approaches for evaluating the toxicity of reactive organochlorines and epoxides in green algae

Niederer

Behra

Harder

et al. 2004

Enviro Toxic and Chemistry

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Reactive electrophilic chemicals, such as reactive organochlorine compounds or epoxides, react specifically with a broad spectrum of nucleophilic biomolecules, including proteins and DNA. Conventional toxicity tests for algae, involving the observation of growth inhibition, i.e., the inhibition of cell multiplication, after several days, yield unreliable information for risk assessment because reactive compounds hydrolyze to different extents during the exposure period. The diversity of their modes of toxic action further complicates effect assessment and calls for methods yielding additional information on the mechanisms of toxicity. One of the primary targets of reactive chemicals in cells is the tripeptide glutathione (GSH), which is important for detoxification but can also be regarded as a toxicity sensor because changes in glutathione levels indicate stress. A vital system for algae is the photosynthetic system, which is indirectly affected by reactive chemicals. The test systems developed in this study for the assessment of reactive toxicity toward algae were therefore based not only on nonspecific toxicity indicators like growth inhibition but also on indicators for disturbance of photosynthesis (inhibition of photosystem II quantum yield) and glutathione metabolism. The application of the developed test systems on Scenedesmus vacuolatus after short-term exposure of 2 h showed that these tests can be used as fast screening tests for algal toxicity and in mode-of-action-based test batteries.

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The Variation in Slope of Concentration–Effect Relationships

Cited by 44 publications

References 25 publications

Development and application of a species sensitivity distribution for temperature‐induced mortality in the aquatic environment

Development and application of a species sensitivity distribution for temperature‐induced mortality in the aquatic environment

Including Mixtures in the Determination of Water Quality Criteria for Herbicides in Surface Water

Mechanistic approaches for evaluating the toxicity of reactive organochlorines and epoxides in green algae

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