Median lethal exposure

Abel, P.D. and S.M. Garner. 1986. Comparison of median survival times and median lethal exposure times for Gammarus pulex exposed to cadmium, permethrin and cyanide. Water Res. 20 579-582. 

Health and Safety Factors. VDE is a flammable gas its combustion products are toxic. Liquid VDE on contact with the skin can cause frostbite. Acute inhalation toxicity of VDE is low median lethal concentrations (LC q) for rats were 128,000 ppm after a single 4-h exposure (52) and 800,000 ppm after a 30-min exposure (53). Cumulative toxicity is low exposure of rats and mice at levels of up to 50,000 ppm for 90 days did not cause any... 

Table 11 summarizes values for the median lethal dose (LD q) for several species. In case of massive exposure, convulsions must be controlled, and glucose, fluid balance, and uriaary output must be maintained. Medical surveillance requires checking for damage to the Hver, the organ that apparently sustains initial damage, and monitoring for changes ia the blood profile. 

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. 

Median Lethal Dosage (mg-min/m3) 3,000-5,000 by inhalation 100,000 by skin exposure. 

Silver et al. reported a median lethal concentration of 1,500 g/m Tby Inhalation, for 10-min exposure of mice. 

Chloropicrin. Median lethal concentration for mice 10-min exposure. U.S. War Department, Chemical Warfare Service, Edge-wood Arsenal, Md. 1942. 8 p. 

Zhao, Y.A. and Newman, M.C. (2004) Shortcomings of the laboratory-derived median lethal concentration for predicting mortality in field populations exposure duration and latent mortality. Environ Toxicol Chem, 23, 2147-2153. 

Median lethal concentration of a test material in the test matrix (e.g., growth medium) that is calculated to exhibit a lethal effect to 50% of a group of test organisms during exposure over a specified period of time. The LC50 and its 95% confidence limits are usually derived by statistical analysis of mortalities in several test concentrations. The duration of exposure must be specified (e.g., 48-h LC50). Volume 1(1,4,10), Volume 2(5). 

As an index for toxicity of gaseous substances, the median lethal concentration (LC 5 0 ) and the threshold limit value (TLV) are used to evaluate acute toxicity. LCso is the gas concentration (ppm) in air which results in the death of 50% of a population of test animals by inhalation. TLV is the threshold limit of exposure which does not cause any serious sickness in workers under normal conditions of an 8 hours day and a 40-48 hour work week. TLV is usually given in combination with the time-weighted-average concentrations for 8 hours per day (TLV—TWA), or with the short time exposure limit (TLV-STEL), which is that exposure which should not be exceeded even for a relatively short period (15-30 minutes), or with the ultimate limit (TLV-C), which defines the exposure level that should not be exceeded under any circumstances. 

Acute inhalation toxicity can be conducted in an exposure chamber. It is recommended, but not required, that nose-only or head-only exposure be used for aerosol studies to minimize oral exposures due to animals licking compound off their fur. For nongaseous pesticides, introduction of the sample in the form of mist or dust becomes a necessity. The animals are exposed for 4 hr and then transferred to other containers for observations for at least 14 d. The median lethal concentration obtained is referred to as inhalation LC30 (Anonymous, 1998). 

The LCtso for inhalation exposures in humans has been estimated to be 1500 mg-min/m (DA, 1992). In animals, median lethal Ct values for sulfur mustard range from 600 to 1900 mg-min/m for 10-min exposures (see Rosenblatt et al., 1975 for review). An LClo (lowest lethal concentration) of 189 mg/m /10 min has been reported for mice (Lewis and Sweet, 1984), and a 5-min LClo of 77 ppm has been reported for dogs (fTll, 1975). 

Fuhr, I., Krakow, E.H. (1945). Median lethal concentrations of H for mice and rats. For various exposure times. MDR 21, March 21 (as cited in McNamara et al., 1975). 

The 10 min median lethal concentrations (LCsqs) reported in the literature for rats and rabbits are 120-210 and 200-300 ppm, respectively. The lethal effect of arsine is dependent on exposure concentration and duration. The rat LC50 at 0.5, 1 and 4-h exposures is 240, 178, and 45 ppm, respectively. Female rats have slightly greater mortality than males. The effects in animals include dyspnea, hematuria, dark material around the head or anogenital area, and pallor of ears and eyes. During necropsy the animals showed red, yellow, or orange fluid in the bladder, stomach, or intestine, and discoloration of the kidneys, lungs, and liver. Most of the available data come from experiments in rats however, some authors state that the rat is not a suitable model for arsine toxicity because of differences in arsenic methylation and excretion compared to humans. 

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