LD50 value

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. 

For example, the LD50 value of sodium lauryl ether carboxylate with 4.5 mol EO is about 3-4 g/kg [51,57] and of sodium myristyl ether carboxylate with 3.5 mol EO about 4 g/kg [57]. 

Alkyl olefinsulfonates (AOS) are essentially nontoxic with reported LD50 values in mice of 3000 mg/kg (oral), 1660 mg/kg (subcutaneous), 170 mg/kg (intraperitoneal), and 90 mg/kg (intravenous). The toxic signs seen at the higher doses included reduced voluntary activity, diarrhea, anemia, dyspnea, and respiratory collapse. Clonic convulsion followed by respiratory collapse was seen in mice given the material intravenously [147,148]. 

The LD50 values for methyl parathion were compared to those for methyl paraoxon, the active metabolite of methyl parathion, in rats, guinea pigs, and mice by Miyamoto et al. (1963b). Methyl paraoxon was 5.4 times more potent than methyl parathion in male rats, 5 times more potent in male guinea pigs, and 1.6 times more potent in mice. 

All reliable lethal doses (LD50 values) for each species and for the acute- and intermediate-duration categories are recorded in Table 3-3 and plotted in Figure 3-2. 

LD50 values for the dermal route of exposure to methyl parathion have been established in acute studies for rats 67 mg/kg for males and females (Gaines 1960), 110 mg/kg for males, and 120 mg/kg for females (EPA 1978e). The LD50 in male mice exposed by dermal application of methyl parathion to their hind feet (rather than shaved backs) was 1,200 mg/kg (Skinner and Kilgore 1982a). The mice were muzzled to prevent oral exposure from grooming. 

The reliable LD50 values for rats and mice for the acute-duration category are recorded in Table 3-4. 

Acute Oral LD50 Values for Some Anticoagulant Rodenticides... 

Mineral oils have very low acute toxicities, i.e. oral LD50 values of around lOg/kg. They are not absorbed via the skin and are insufficiently volatile to produce harmful vapours at room temperature. Additives are used in small quantities for specific properties but these do not normally affect the health and safety characteristics. Dermatitis may be caused by repeated or prolonged contact of mineral oils with the skin. Such contact with higher boiling fractions over many years can result in warty growths which may become... 

A QSAR for the acute toxicity of new hypoglycemic agents [48] was internally cross-validated, but used LD50 instead of log LD50 as the dependent variable, and (more seriously) used LD50 values in g kg rather than in a molar unit such as mmol kg. ... 

LD50 values can be determined for alcoholic extracts of sponges by... 

This code is of limited usefulness (see para 1.5.3) (it is supposed to contain in one figure only the level of the three factors inflammability, toxicity and stability). So far as toxicity risk is concerned, the definition of the three degrees is clear and makes it easy to choose between the different risk levels, it is defined by LD50 values (given in mg/kg) and LC50 (given in ppm). 

When analysing the level of measurement error of LC and LD50 it was realised that the set of data was difficult to use since it is hardly reliable, and therefore of questionable coherence amongst all the figures. In order to find an answer to this a sample of the LC and LD50 values were submitted to an analysis based on principal components (PCA). it would take far too much time to describe this method, besides this goes beyond our subject, its purpose is to look for and classify the different types of information contained in a complex table of quantitative data. 

When some values seem questionable a question mark in brackets is added next to these values. If two very different values are given for one substance the doubtful data source is noted. For instance, for o-cresol, two LD50 values for the rat orally are mentioned as follows LD50 o-r 121 1350 (Merck). This means that the 1350 value that seems high and that applies to a phenol that is particularly corrosive and toxic (see Code du travail (ie Labour Code)) was suggested by the Merck Index. 

Weinman and Decker list the LD50 values against adult grasshoppers (M. differentia alis) for a number of the more common toxicants, both as contact poisons and as stomach poisons, giving the values shown in Table VI (H). 

Table VI. LD50 Values for Single Compounds Tested for Contact and Stomach-Poison Effect against M. differentialis Adults...

Johannsen and colleagues (1977) report dermal LD50 values for rabbits at levels of >3,700 mg/kg for a group of triaryl phosphates, >5,000 mg/kg for dibutyl phenyl phosphate, 5,000 mg/kg for both asymmetrical and symmetrical triaryls, and >3,100 mg/kg for tributyl phosphate. This study looked at structural activity relationships for the organophosphate esters. 

It is noteworthy that gelsenicine is the most toxic alkaloid isolated so far from G. elegans. The LD50 value is 185 /ig/kg for mice on intraperitoneal injection. 

Oral LD50 values for lead or its inorganic or organic salts were not found in the available literature. LDl0 values for a number of lead compounds have been estimated (Sax 1984, see Table 2-3). An LDlo is defined as the lowest dose of a substance given over any given period of time in one or more divided portions reported to have caused death (Sax 1984). Furthermore, unlike LD50 values, these values are not derived statistically, and comparisons between compounds and species are difficult. 

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