Predicted no effect concentrations

For the ecological assessment, risk analysis was based on the traditional PEC/ PNEC ratio (Hazard Quotient) where PEC is the predicted environmental concentration (resulting from chemical analysis) and PNEC the predicted no-effect concentration. Ecological assessment for aquatic species was based on rainbow trout or fathead minnow while terrestrial assessment was based on small rodents like mice rats and rabbits. Exposures associated with HQ<1 were considered negligible. 

The objective is to predict the concentration of the substance below which adverse effects in a particular environmental compartment are not expected to occur, i.e., the predicted no effect concentration (PNEC). However, in some cases, it may not be possible to establish a PNEC, and a qualitative estimation has to be made instead. An assessment factor is applied to... 

Alternative Methods PNEC Predicted no effect concentration... 

The method compares the predicted environmental concentrations (PECs), as indices of exposure, with predicted no effect concentrations (PNECs), as indices of... 

In general, only valid studies were used to derive predicted no effect concentrations (PNECs). Because in some cases only a few valid data were available, studies valid with restrictions have been used based on expert judgement. Invalid or non-assignable studies have not been used. In instances of volatile compounds, valid studies were generally those using closed, flow-through systems, preferably with analytical measurements. 

The risk posed to predators eating contaminated fish is determined by comparing the estimated daily intake (EDI) of fish predators (birds or mammals) with the predicted no-effect concentration in these predatory species. If adequate data are missing, the latter value was estimated from laboratory rodent or meat-eating animals (Table 3.3). 

The assessment of whether a substance presents a risk to the receiving environmental compartment is based on a comparison of the measured or predicted environmental concentration (PEC) of the chemical of concern with the predicted no effect concentration (PNEC) to organisms in the ecosystem. This is briefly discussed in Chapter 7.4. Studies carried out so far, e.g. by Vandepitte and Feijtel [91], show that the risk of anionic surfactants such as LAS, AE and AES for the aquatic environment is low, since the PECs are always lower than the maximum permissible concentrations. 

MEC measured environmental concentrations ( ig L ), PNEC predicted no effect concentration, REEmec literature reference for the MEC value, REEnmc literature reference for the PNEC value... 

Effects assessment, by, as in the case of risk assessment for chemicals and pesticides, determining a set of marker organisms (including algae, zebrafish, insect larvae, benthic worm, water flea, etc.) that represent ecosystem components and food networks and are used to indicate acute and chronic effects. This step is also used to define the predicted no-effect concentrations (PNECs). 

The environmental risk assessment approach most commonly adopted consists of estimation of the risk quotient (RQ) (as suggested by Hernando et al. [103]), which is defined as the ratio between the environmental concentration (measured or predicted, respectively MEC and PEC) and the predicted no-effect concentration (PNEC), and can be used to collocate compounds in one of three risk bands RQ < 0.1, minimal risk to aquatic organisms 0.1 < RQ < 1, median risk and RQ > 1, high risk [103—105]. In their risk assessment calculations, [106], further to [107], estimated PNEC values at 1,000 times lower than the most sensitive species assayed, so as to take into account the effect on other, potentially more sensitive, aquatic species to those used in toxicity studies. 

Guidance to date supports the risk assessment principles for general chemical substances already published by the Commission (1996). Consequently, the risk characterisation simply involves a quantitative comparison of the outcome of the hazard/effects assessment with the exposure assessment. For human risk this involves the calculation of the TER (Toxicity Exposure Ratio) and comparing it with the MOS (Margin Of Safety). For environmental risk the PEC/PNEC ratio (Predicted Environmental Concentration versus the Predicted No-Effect Concentration) for the various environmental compartments. 

REACH uses the terms derived no-effects level (DNEL) for hazards to human health and predicted no-effect concentration (PNEC) for hazards to the environment. 

Table 8.4 Predicted environmental concentrations (PECs), predicted no-effect concentrations (PNECs), and risk quotients (RQs) for nano-Ag, nano-Ti02, and CNTs in the environmental compartments air, water, and soil calculated in a realistic (RE) and a worst-case (HE) scenario.

Feijtel, T.C.J. and Belanger, S.E. (1999) Predicted no-effect concentrations and risk characterization of four surfactants linear alkyl benzene sulfonate, alcohol ethoxylates, alcohol ethoxylated sulfates, and soap. Environ Toxicol Chem, 18, 2653-2663. 

The ecotoxicology of pharmaceuticals is of critical concern to the issue of PIE. The all important question is not whether pharmaceuticals are present in the environment-there is ample evidence that they are-but, at the concentrations at which they are found, whether they do any harm The almost universally used paradigm for attempting to answer this question is the comparison of the Predicted Environmental Concentration (PEC) with the Predicted No Effect Concentration (PNEC)-the so called PEC/PNEC ratio. 

As noted previously, the use of (Q)SAR for effects assessment nearly always uses a static assessment factor to extrapolate to a predicted no-effect concentration (PNEC). Assessment factors may be as high as 10000 (Environment Canada 2003). 

Geographic Information System (GIS) A system that allows for the interrelation of quality data (as well as other information) from a diversity of sources based on multilayered geographical information-processing techniques, hazard (toxic) The set of inherent properties of a stressor or mixture of stressors that makes it capable of causing adverse effects in humans or the environment when a particular intensity of exposure occurs. See also risk, hazard assessment (HA) Comparison of the intrinsic ability to cause harm with expected environmental concentration. In Europe, it is typically a comparison of predicted environmental concentration (PEC) with predicted no-effect concentration (PNEC). It is normally based on a single value for effects and exposure. It is sometimes incorrectly referred to as risk assessment. 

The Japan Soap and Detergent Association has voluntarily implemented monitoring surveys since 1994 on the concentration of surfactants in the surface layer water of rivers in Japan in order to monitor the situation of persistence of surfactants in public waters and evaluate the effects ofsurfactants on aquatic organisms [2 ]. Table 8.7 shows the measurement results of the concentrations of four surfactants regulated by the PRTR system in the major Japanese rivers during the period from June 1998 to September 2003 (mean levels and highest levels) [2]. The highest levels in the table were all lower than the predicted no-effect concentrations (PNEC) [3, 4] and therefore it was considered that the surfactants cause almost no risks to the ecosystem in the environmental waters. 

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