NOECs concentrations

Note. NOEC = Concentration that does not produce any effect. 

Table 7 Example application of process in Box B to evaluate the risk of dioxins in Dutch sediments. No observed effect (NOEC) concentrations for chronic toxicity of dioxins in vertebrates (immune, reproductive and developmental toxicity) expressed as internal concentration (ng TEQ/g Iw). The sediment to fish bioconcentration factor is set at 4 (ng TEQ/g Organic Carbon to ng/g lipid weight in fish) based on Traas et al. (2001). Based on a species-specific biomagnification factor (BMP) from fish to animal (ng TEQ/g Iw) the internal NOEC is extrapolated to a NOEC in sediment. These data are used to construct the SSDs in Figures 5 and 6.

Aquatic toxicity is reported in mg/L for Pimepha/espromealas (fathead minnow), 69-h LC q 7650 (17) for Daphnia magna (water flea), 48-h EC q 3310 (18) for Mjriophjllum spicatum (water milfoil), phytotoxicity (EC q for growth) 5962 (19) and for Pana breviceps (frog), no observed effect concentration (NOEC) 400 (20). LC q and EC q are lethal and effect concentrations, respectively, for 50% of the subjects tested. 

In a continual biocoenosis test (Riverine biocoenosis model) for LAS the biocoenotic NOEC value of >0.65 mg/L has been determined. The test was carried out with a starting concentration of 1.1 mg/L LAS/L over a period of 5 weeks. The NOEC value represents the effect caused by the original detergent and the effects caused by the catabolites as well [297]. The NOEC value shows that biocoenosis reacts more sensitively to compounds than the most sensitive laboratory species, which according to general opinion should not be generalized. 

Daphnid (Daphnia magna) DBTC 21-day NOEC (survival and reproduction) 0.015 = highest concentration tested 0.015 ABC (1990b)... 

Dibutyltin. A larger data set exists for dibutyltin, including both acute and long-term test results. The lowest concentration identified was a chronic NOEC of 0.015 mg/1 for Daphnia magna exposure to dibutyltin chloride. Long-term values were available across three trophic levels, and, therefore, an uncertainty factor of 10 was considered appropriate. 

Silva, E., Rajapakse, N., and Kortenkamp, A. (2002). Something from nothing — Eight weak estrogenic chemicals combined at concentrations below NOECs produce significant mixture effects. Environmental Science and Technology 36, 1751-1756. 

Moreover, water quality is to be maintained or restored in such a way that human beings do not suffer any health damage as a result of the pollutant content of the fish they consume. The ecotoxicological data required in order to protect aquatic organisms and fish populations are the so-called No Observed Effect Concentration (NOEC) data. 

Buec. NOEC (No Observed Effect Concentration) Safety Factor... 

The no-observable-effect-concentration (NOEC) for reproduction was 168 mg/kg diet the NOEC for growth was 598 mg/kg. Copper concentrations in whole mites increased significantly at dietary loadings >168 mg/kg... 

TCDD concentrations in eggs of seven species after exposure as fertilized eggs to nominal concentrations of 9-285 ng 2,3,7,8-TCDD/L for up to 540 h. Lowest observed effect concentration (LOEC) in ng/kg FW associated with adverse effects on su rvival or growth 32 days post exposure vs. no observed effect concentration (NOEC) in ng/kg FW Lake herring, Coregonus artedi 270 vs. 175 Fathead minnow, Pimephales promelas ... 

Note (a) BCF is hioconcentration factor, NOEC is no-observed effect concentration. (b) For marine environmental risk assessment, half-life data in freshwater sediment can be overruled by data obtained under marine conditions. (c) Substances are classified when they fulfil the criteria for all three inherent properties for P, B and T. However, there is certain flexibility for instance in cases where one criterion is marginally not fulfilled but the others are exceeded considerably. (d) R48 Danger of serious damage to health by prolonged exposure. ... 

NOEC No-observed effect concentration vPvB Very persistent and very bioaccumulative... 

A subsequent study in the same areas also included biological samples [12]. Again, the Aire river contained the highest concentrations, with total extractable NP + A9PEOi+2 concentrations of 15-76 pg L 1. In many samples of this river, levels exceed the no observed effect concentration (NOEC) for vitellogenin induction in trout (5-20 pg L 1). However, in most samples of the other investigated rivers, levels were... 

For the derivation of the PNEC several approaches have been proposed. Generally these can be categorised into three distinct assessments a conservative, a distributional, and a mixture toxicity approach. In conservative approaches, usually the most (realistic) sensitive endpoint such as LC50 or the known no observed effect concentration (NOEC) is taken and divided by an uncertainty factor (10-100). The selected uncertainty factor value depends on the type of endpoint and the number of available data, and is applied to account for laboratory to field extrapolations, species differences in sensitivities, and similar uncertainties. In distributional approaches, a series of, or all available, literature data are taken and a selected cut-off value is applied to the distribution of these data. The cut-off value may be, e.g., the concentration value that will protect 95% of the species (tested). In general, again an uncertainty factor (usually of 10) is then applied to take into account species differences. In the mixture toxicity approach, a similar mode of action is assumed for the assessment of the combined (additive) effect of the mixture. All relevant mixture components are scaled relative to the most potent one. This results in relative potencies for each component. The total effect of the mixture is then evaluated by... 

SPY sulfapyridine, SDZ sulfadiazine, SMX sulfamethoxazole, SMZ sulfamethazine, SCP sulfachloropyridazine, STZ sulfathiazole, SCT sulfacetamide, AcSMX N -acetylsulfamethoxazole, AcSDM N -acetylsulfadimethoxine, AcSDZ N -acetylsulfadiazine, EC50 Median effective concentration (mg/L), LC50 Median lethal concentration (mg/L), NOEC No-observed-effect concentration (mg/L) LOEC lowest-observed-effect concentration (mg/L), h hours, min minutes, d days... 

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