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Conservation Principles and Their Application in Environmental Management
Published in Sven Erik Jørgensen, A Systems Approach to the Environmental Analysis of Pollution Minimization, 2020
Environmental management is particularly interested in the assessment of safe concentrations, i.e., concentrations where no effects are observed. Terms widely used in environmental management include: No observed effect concentration (level) — NOEC (NOEL): defined as the highest concentration (level) of a test chemical substance to which the organisms are exposed that does not cause any observed and statistically significant adverse effects on the organisms compared with the controls.Predicted no effect concentration — PNEC: which is the environmental concentration below which it is probable that an unacceptable effect will not occur according to predictions. PNEC is found from NOEC by use of a suitable safety factor (see Chapter 10).
Planning, monitoring, verification, and sustainability of soil remediation
Published in Katalin Gruiz, Tamás Meggyes, Éva Fenyvesi, Engineering Tools for Environmental Risk Management – 4, 2019
K. Gruiz, M. Molnár, É Fenyvesi
The risk-based approach is utilized in the verification tool box to quantify the potential impacts in the beginning and at the end of the project. The initial and residual risk is calculated by the comparison of the Predicted Environmental Concentration (PEC) of the site at the beginning and at the end of remediation to the Predicted No Effect Concentration (PNEC). This ratio is called the risk characterization ratio (RCR), which can be the ratio of two concentrations (the measured to the allowable) or two effect values: the measured to the no effect. The term “predicted” refers to the uncertainties, that must be taken into consideration. PEC is calculated from the values measured at the transformer station and the same concentration is thought to be outside the station fence of the City Park’s territory. The applied PNEC value is a site-specific target value – representing a “no risk” situation for groundwater, soil, or other compartments also considering land uses. The risk-based quality criteria for groundwater (w) is this: RBQCiw = 0.5 mg/L in the territory of the transformer station (an industrial site [i] with restricted access), but only RBQCrw = 0.2 mg/L in the area of the surrounding City Park, a recreational (r) area.
Mixture Risk Assessment of Chemical: from the Theory to the Application
Published in Nathalie Chèvre, Andrew Barry, Florence Bonvin, Neil Graham, Jean-Luc Loizeau, Hans-Rudolf Pfeifer, Luca Rossi, Torsten Vennemann, Micropollutants in Large Lakes, 2018
Vincent Gregorio, Nathalie Chèvre
Originally, risk assessment of chemicals were developed for a single substance (European Chemicals Bureau, 2002). The risk procedure compares the environmental concentrations of a compound with a toxic threshold. The risk is assumed to be negligible when this ratio is lower than the value of one. The toxicity of a given compound is determined based on its dose-effect relationship established in the laboratory on typical species: alga, invertebrate or fish for the aquatic compartment. These dose-effect relationships allow the determination of endpoints such as the no-observed effect concentration (NOEC) or effect concentration of x% (ECx). These values can be used to derive the predicted no-effect concentration (PNEC) in the environment, which is calculated based on these NOEC/ECx values divided by an assessment factor (AF) (European Chemicals Bureau, 2002). In the 1980s, the new concept of the species sensitivity distribution (SSD; (Posthuma et al., 2002)) was proposed to describe the percentage of affected species for a given substance at a given concentration. This method allows the calculation of threshold values (hazardous concentrations), which are more robust than the PNEC. Statistical SSD approach is therefore a great improvement in terms of ecological risk reasoning. The disadvantage is that it requires knowledge of NOEC values for several different species, for a given substance, which is rarely the case in reality (Chèvre et al., 2006).
Occurrence of booster biocides in the global waters and a tiered assessment for their ecological risk to the aquatic system
Published in Human and Ecological Risk Assessment: An International Journal, 2022
Keyan Cui, Xianhai Yang, Huihui Liu
The log-logistic model was the most suitable model for SSD curves. The fitting parameters for each biocide were listed in Table S4, and the SSD curves were presented in Figure 2. PNEC was a crucial parameter to evaluate the toxic effect of a compound to the aquatic organisms. The lower the PNEC value of a compound was, the greater its effect would be on aquatic organisms. In this study, the order of PNEC values for the seven compounds was as follows: Irgarol 1051 < GS26575 < Chlorothalonil < DCOIT < Dichlofluanid < Diuron < BIT. Among them, Irgarol 1051 was the most toxic with the PNEC value of 7.60 ng/L. Even though Irgarol 1051 was often reported as biodegradable (Lambert et al. 2006; Hall et al. 2009), its primary degradation product (GS26575) also had greater toxicity than other biocides, with the PNEC value of 20.0 ng/L. Chlorothalonil and DCOIT had similar toxicity with the PNEC value of 50.0 and 64.2 ng/L, respectively. Dichlofluanid and Diuron had similar toxicity with the PNEC value of 520 and 718 ng/L, respectively. BIT was the least toxic with the PNEC value of 3420 ng/L.
Blending antibiotic resistance into environmental risk assessment of antibiotics: A case study in coastal waters of the Bohai Bay, China
Published in Human and Ecological Risk Assessment: An International Journal, 2019
The assessment factor method is an extrapolation method developed for estimating PNEC values for chemicals. The general principle is that the toxicity data from the laboratory test is divided by an appropriate assessment factor. The assessment factor would be higher if the available toxicity data are sparser. When the NOEC data for algae, crustaceans/invertebrates, and fish were available and not more than four, the assessment factor approach was used to calculate the PNEC values (Chen et al.2016; ECHA 2008; Liu et al.2016; Yao et al.2017). The PNEC value was derived by dividing the NOEC value from the most sensitive species by the factor of 1000, 500, or 100, where one, two, or three trophic levels were covered, respectively (ECHA 2008). The assessment factor of 500 could be reduced to 100 when NOEC data from a third taxonomic group was available. In this study, the PNEC values were calculated based on the toxicity data, and the assessment factors of 1000, 500, and 100 were used. PNEC values and corresponding assessment factors are shown in Table S2.
Acute inhibition of hospital and medical laboratory wastewater on activated sludge
Published in Environmental Technology, 2022
Recep Partal, Selda Murat Hocaoglu, Nevzat Özgu Yigit
Moreover, medical laboratory wastewater (MLW) was found in the very toxic category according to the Microtox toxicity test (ISO/EN/DIN 11348) using the marine bacteria (Vibrio Fischeri) [17]. In previous studies, the toxic effects of some specific chemicals such as mercury, gadolinium, platinum, and pharmaceuticals which may be found in HWs, on different groups of organisms have been determined [18, 19]. For example, the Predicted No-Effect Concentration (PNEC) of mercury in sewage treatment plants is given 2.25 µg/L [20]. PNEC is the concentration of a substance that adversely affects aquatic organisms. However, since it is a chemical-specific PNEC, it does not represent the mixed wastewater matrix.