Maximum tolerable concentration

To estimate a maximum tolerated concentration following a 6-h exposure, groups of five male and five female Crl CD-l(ICR)BR mice were exposed at 9,700, 20,000, 30,000, 41,000, or 80,000 ppm (Vlachos 1988). The mice were observed for clinical signs during exposure and for 2-3 d postexposure. Mice... 

In spite of the promising results obtained by using TIQDT, we found also some problems to be fixed. The main detected problems were (1) the variability in the size and number of thyroid follicles in each animal, (2) the fact that some TGFDs could impair the size or the number of thyroid follicles, but not the concentration/API of T4 signal inside of the quantified follicles, (3) some autofluorescence may be found with the set of immunofluorescence filters used, and (4) clear signs of systemic toxicity were found in eleutheroembryos exposed to some chemicals at the maximum tolerated concentration. For an optimized TIQDT protocol, we increased the... 

Suppose there was a major spill of 600 kg of a toxic chemical (that can dissolve In water) in a river that is 20 m wide and 3 m deep. The local government of a city 180 km downstream from the spill site asks you to evaluate the water quality (whether it can be piped into the city water supply) in the river next to the city as a function of time. Suppose water flow rate is 2 m/s and width and depth of water of the river are constant. Assume an eddy diffusivity of 10 m /s. You find from ERA guidelines that the maximum tolerable concentration of the toxic substance for drinking water is 0.01 ppb. 

A clear pumping policy has to be formulated for every region in accordance with its hydrological structure. It seems useful to sum up the accepted policy in terms of red lines of maximum tolerable lowering of the water table and maximum tolerable concentrations of water quality key parameters. These parameters have to be monitored routinely. Electric conductivity and water table may be monitored continuously by instruments placed in observation wells or pumping wells. In the latter case, the respective... 

Drinking water standards define the maximum tolerable concentration of a long list of dissolved compounds. 

Table 3. Overview of the additives that have been proposed as solubility enhancers, to reduce adsorption and non-specific binding and/or to increase the biorelevance of in vitro absorption models. The table refers to the model used to evaluate the compatibility, the maximum tolerable concentration, the compartment in which the additive is included, the expected effect, the compounds tested in presence of the additive and the reference.

Number in parentheses is the relative selectivity for the interfering ion over the test ion (see The Selectivity Coefficient below). Interference concentrations given represent maximum tolerable concentrations. 

Adverse or harmful effects will occur if measured or predicted environmental concentration (PEC) in various environmental media such as water, soil, sediment and the atmosphere is higher than predicted no effect concentrations (PNEC, or maximum tolerable concentration MTC) based on the above ecotoxicity test results. PNEC values combine the ecotoxicity data with an assessment factw (AF). Data from short-term studies in the laboratory generally need large AFs (100-KXX) are applied to the lowest L(E)C5o) data from long-term laboratory studies or ecosystem field studies need smaller AFs (usually 10 applied to the lowest no observable effect levels (NOEL). 

Tab. 9.2-7 Maximum tolerable concentrations for Cl, CL and CL-compounds selected data...

Filters of class PI are not usually used in combination with full masks, rarely with half or quarter masks. Because of the significantly lower rate of leakage and the higher concentration of particles, there is an clear advantage in performance and protection of full masks over half or quarter masks. This can easily be seen in a comparison of the maximum allowable concentrations given in Tables 6.21 and 6.22. Table 6.21 gives an overview of retention capability, maximum tolerable concentration of contaminants, and use areas of all common particle filters combined with a full mask. 

Aquatic toxicity potential is calculated based on tbe maximum tolerable concentrations of different toxic substances in water by aquatic organisms. 

Hutchinson TH, Bogi C, Winter MJ, Owens JW (2009) Benefits of the maximum tolerated dose (MTD) and maximum tolerated concentration (MTC) concept in aquatic toxicology. Aquatic Toxicology 91 197-202. 

Concentrations of 1300 ppm to 2000 ppm are lethal on brief exposure of about 1 minute. Concentrations in the range of 1000 ppm to 1300 ppm are dangerous if breathed for 30 minutes. The maximum tolerable concentration for exposure of 1 hour is in the range of 50 ppm. The maximum tolerable exposure for several hours duration is approximately 10 ppm. 

Calculation of the maximum tolerable concentration (MTC). MTC is the highest substance concentration which has no significant effect on the release of arachidonic acid under the described experimental conditions. To determine the MTC of the test substance, a confidence interval was calculated by means of variance analysis for both the RPMI cell control and the dose-response curve up to the 10-fold pH]-AA release compared to the cell control. The first concentration at which a significant difference was found between the AA release of the test substance and that of the cell control was determined. The next lower concentration of the test substance was taken as maximum tolerable concentration (MTC). 

Statistical evaluation. The maximum tolerated concentrations (MTC) obtained by the in vivo test procedure served as a basis to rank the test substances. The following statistical tests were performed Calculation of the rank correlation coefficient according to Spearman (rs) for distribution-free dependence, calculation of the linear regression and the linear correlation coefficient (r ). In all tests the level of significance was a = 5%. 

The dose-response curves clearly demonstrate that the cells respond to all the substances with a concentration-dependent increase in [3H]-AA release. However, the effective ranges of substance concentrations differed by some orders of magnitude. Correspondingly, this was also true for the maximum tolerable concentrations (MTC values. Table 1). For lysolecithin and SDS, the MTC values amounted to 0.5 and 2.0 pg/ml, respectively, for formamide and DMSO 50 and 100 mg/ml, respectively. The MTC values of the remaining substances - dimethoate, chloramine and 2,4-D - (31, 160 and 1000 pg/ml) demonstrated their position between the extremely toxic and the well tolerable substances. 

Table 1. Maximum tolerated concentrations (MTC) of seven test substances determined from the Draize eye irritation test (EIT), and the [ HI-AA release test (pH]-AART)... 

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