Toxic concentration, lethal

Health, Safety, and Environmental Factors. Sulfur dioxide has only a moderate acute toxicity (183). The lowest pubHshed human lethal concentration is 1000 ppm for 10 months. The lowest pubHshed human toxic concentration by inhalation is 3 ppm for 5 days or 12 ppm for 1 hour. The lowest pubHshed human lethal concentration is 3000 ppm for 5 months. In solution (as sulfurous acid), the lowest pubHshed toxic dose is 500 flg/kg causing gastrointestinal disturbances. Considerable data is available by other modes of exposure and to other species NIOSH standards are a time-weighted average of 2 ppm and a short-term exposure limit of 5 ppm (183). 

The toxicity of many bleaching chemicals is also reflected in observed effect doses and concentrations. These measures include lowest pubHshed toxic concentration (TC q), concentration that is lethal to 50% of a specified population (LC q), lowest pubHshed lethal dose (LD q), and dose that is lethal to 50% of a specified population (LD q). Some relevant values of these are Hsted in Table 3. 

The bad guys, shown in pink in Figure 2.8, are toxic, often lethal, even in relatively small quantities. Several of the essential trace elements become toxic if their concentrations in the body increase. Selenium is a case in point. You need about 0.00005 g/day to maintain good health, but 0.001 g/day can be deadly. That s a good thing to keep in mind if you re taking selenium supplements. 

Exposures resulting in nonlethal, irreversible effects of dimethylhydrazine were not well defined. For most studies, responses were described in terms of no visible signs of toxicity or lethality. However, Weeks et al. (1963) described nonlethal (but reversible) effects in dogs exposed to 1,1-dimethylhydrazine at varying concentrations. In this study, dogs were exposed to 1,1-dimethylhydrazine at 1,550 ppm or 4,230 ppm for 5 min or 360, 400, or 1,530 ppm for 15 min. The highest cumulative exposures at each of two exposure periods (Ct =352-383 ppm-h) were associated with marked tremors, convulsions and death, while the lower concentration exposures at each of two periods caused behav... 

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. 

Sakata M, Kazama H, Miki A, et al Acute toxicity of Fluorocarbon-22 Toxic symptoms, lethal concentration and its fate in rabbit and mouse. Toxicol Appl Pharmacol 59 64-70, 1981... 

Studies in animals have shown that cresols can be lethal when exposure is through the inhalation, oral, or dermal routes. The lethal exposure levels varied from 1,350 to 2,020 mg/kg in orally exposed rats and 300 to 2,830 mg/kg in dermally exposed rabbits, depending on the isomer tested. By either route, m-cresol was the least toxic isomer. Lethal levels were not determined in inhalation studies, but one study (Campbell 1941) reported that brief repeated inhalation exposures produced lethality at concentrations that were not lethal when a single, longer exposure period was used. The estimated lethal dose in humans (2,000 mg/kg) is within the range of values reported in other species. Other observations regarding the lethality of cresols to animals might also apply to acutely-exposed humans. 

Linking toxicity and chemical data can be useful in the early stages of a TRE, but may be most valuable when the TIE treatments implicate a particular substance(s) as the cause of toxicity. A common approach is the use of Toxic Units (TUs). Lethal TUs express the degree of effluent toxicity, or the concentration of substance, as a fraction of the LC50. Similarly, sublethal TUs are expressed as a fraction of the IC25 or IC50 (Environment Canada, 1999). TUs are dimensionless, and allow for normalization of LC50 data. The TU can be used to predict toxicity of an effluent based on the measured toxicant concentrations. 

In both cases, the blood metamfetamine concentration was less than the lethal concentration of 4.5 pg/ml. Morphine concentrations were higher than the non-toxic concentration of 0.3 pg/ml. It is unlikely that morphine was the cause of death, because it would have caused hypothermia instead of hyperthermia. It is more likely that morphine interacted with metamfetamine, increasing the hyperthermic effect that is typical of metamfetamine overdose. This would explain why hyperthermia caused death, despite a non-lethal blood concentration of metamfetamine. 

Toxicity. Blood concentrations greater than about lOpg/ml may be toxic or lethal. 

Toxicity. The lethal dose is estimated to be in excess of about 2 g. Blood concentrations greater than about 0.5 pg/ml may cause toxic reactions and concentrations greater than 5 pg/ml may be lethal. 

Toxicity. This statement may include drug concentrations in blood or ofrier body fluids or tissues, which have been reported to be associated with toxic or lethal effects. Because of intersubject variations or other variable factors, the reported toxic or lethal concentrations may occasionally lie close to or within the therapeutic range. 

In some monographs, the toxic or lethal blood concentrations are stated in the form 60 to 89 to 150 jLig/ml. These figures have been obtained from a survey of a number of reported cases and represent the maximum concentrations foimd in 10%, 50%, and 90% of the subjects, respectively. 

This substance has an odor like soured fruit and produces a burning sensation of the mucous membranes and severe irritation and lacrimation of the eyes Tcith acute pain in the forehead. As a lacrimator it is seven times as pow erful as bromacetone. Thus, brombenzyl cyanide can be detected in concentrations as low as 1 100,000,900 (0.000087 mg. per liter) it has an irritating effect on the eyes in concentrations of 0.00015 mg. per liter and it produces lacrimation in concentrations of 0.0003 mg. per liter. A concentration of 0.0008 mg. per liter produces an intolerable irritation, and a concentration of 0.90 mg. per liter is lethal on 30 minutes exposure. It is thus less toxic than phosgene and, owing to its low volatility, toxic concentration cannot be realized in the field. 

Physical Properties. Pure soman is a colorless liquid with a somewhat fruity odor. It has density 1.01 g/mL (20°C), vapor pressure of 0.27 mm/Hg (20°C), mp of —80°C, and bp of 190°C (85°C at 15 mm/Hg). Distillation is accompanied by decomposition that begins near 130°C. Soman s solubility in water is about 20% at 25°C. It is only about 20% as soluble in water as is tabun. With two different chiral centers, it exists as four stereoisomers (Benschop et al., 1985), each with a different toxicity. The lethal concentration (inhalation) in humans is estimated at approximately 25-50 mg min/m (Somani et al., 1992). 

In order to prevent SO2 emission, H2S has to be removed from gas streams prior to combustion. Apart from environmental reasons, removal of H2S from waste gas streams is also required for health reasons (H2S is a toxic gas, lethal at concentrations exceeding 600 ppm) and to prevent corrosion of equipment. Gases that can contain H2S and need treatment are, for instance, natural gas, syngas and biogas (formed in anaerobic wastewater treatment). 

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