Lethal concentration value

Alexander and associates (1985) determined the 48-hour median lethal concentration values for 2,4-D to aquatic organisms. These values are 25, 325, 290, and 358 mg/L for Daphnia magna, fathead minnows, bluegill, and rainbow trout, respectively. 

A chronic feeding test was performed for 21 days with aldicarb, which showed medium lethal concentration values of 1.6, 2.0, and 3.9mg/kg for honey bees, N. melanderi, and M. rotundata, respectively [30]. With IGR insecticides, LC50 estimated on young bumble bee larvae was higher for diflubenzuron than for fenoxycarb while the converse was observed for honey bees [48]. 

Lethal dosage values (LDjg based on oral administration to rats) of solvents are used to represent their toxicities. Lethal concentration values (LCjq) are also being used because, in most cases, solvent poisoning is caused by inhalation of solvent vapor. 

The LC50 is the lethal concentration of chemical (e.g. in air or water) that will cause the death of 50% of the sample population. This is most appropriate as an indicator of the acute toxicity of chemicals in air breathed (or in water, for aquatic organisms). Table 5.11 illustrates the use of LD50 values to rank the toxicity of substances. 

Elemental bromine is a readily evaporating liquid (pBr at 1 °C = 0.23 bar) with high reactivity. Because of the good solubility of Br2 in lipids, its aggressive and toxic properties affect skin and mucous membranes (bronchi). The MAK value of elemental Br2 is defined as 0.1 ppm (0.7 mg m 3), while the sense of smell is affected at a value of 0.01 ppm. The lethal concentration (around 100-200 ppm) is reached for example, by twice the MAK value, 5 min, eight times per working unit [91, 92]. 

Lethality Mammalian systems Aquatic vertebrates and invertebrates Plants Lethal dose5o (LD50) Lethal concentration 50 (LC50) Both LD50/LC50 values greater than a reference compound... 

Lethal concentration 50 (LC50) is the vapour concentration of a substance in air, which kills 50% of the animals exposed. This estimate comes from a protocol that was statistically controlled. This value depends on the animal chosen for the experiments and exposure time. The three animals that are most commonly used are in descending order rat, mouse and rabbit. It is a parameter that estimates risk level by inhalation, which is the most important means of penetration involving toxic substances in the work place. 

Table III presents the results of calculating the "time to lethal concentration" for each one of the PVC products investigated. The toxic potency values used for all the materials are based on 30 min exposures in the NBS cup furnace toxicity test, in the Non-Flaming mode, the one most relevant to this scenario.

In all cases, the concentrations of malathion and fenitrothion measured in water (up to 5.8 and 1.2 pg/L, respectively) were below the LC50 (lethal concentration 50%) values reported for these compounds in oysters and mussels, which range between 2.7 and 278 mg/L in the case of malathion, and between 10.3 pg/L and 123 mg/L in the case of fenitrothion (http //www.pesticideinfo.org). However, it has to be stressed that these LC50 values express acute toxicity, that both malathion and fenitrothion might be bioaccumulated by molluscs (as their detection in biota suggests), and that aquatic organisms are exposed to a variety of contaminants, some of which could show synergetic or additive effects [40]. Further matters of... 

The New Jersey Department of Environmental Protection uses the TXDS method of consequence analysis to estimate potentially catastrophic quantities of toxic substances, as required by the New Jersey Toxic Catastrophe Prevention Act (TCPA). An acute toxic concentration (ATC) is defined as the concentration of a gas or vapor of a toxic substance that will result in acute health effects in the affected population and 1 fatality out of 20 or less (5% or more) during a 1-hr exposure. ATC values, as proposed by the New Jersey Department of Environmental Protection, are estimated for 103 extraordinarily hazardous substances and are based on the lowest value of one of the following (1) the lowest reported lethal concentration (LCLO) value for animal test data, (2) the median lethal concentration (LC50) value from animal test data multiplied by 0.1, or (3) the IDLH value. 

As the duration of exposure of the rats increased, the LC o (lethal concentration, 50% kill) value decreased. Maximum nonfatal single exposures for rats were 1.2 minutes at 10,000 ppm, 2.4 minutes at 5,000 ppm, 6 minutes at 3,000 ppm, 12 minutes at 1,600 ppm, 36 minutes at 400 ppm, 2 hours at 200 ppm, and 16 hours at 100 ppm, the longest exposure tested. In other species exposed to 1,2-dibromoethane by Rowe et al. (1952), maximum nonfatal single exposures for guinea pigs were 2 hours at 400 ppm and 7 hours at 200 ppm, the longest exposure tested. 

The highest NOAEL value and the reliable lethal concentrations for each species for the acute-duration category, in rats for the intermediate-duration category and in rats and mice for the chronic- duration/category are recorded in Table 2-1 and plotted in Figure 2-1. 

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