Lethal dose LDS

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. 

Environmental Impact of Ambient Ozone. Ozone can be toxic to plants, animals, and fish. The lethal dose, LD q, for albino mice is 3.8 ppmv for a 4-h exposure (156) the 96-h LC q for striped bass, channel catfish, and rainbow trout is 80, 30, and 9.3 ppb, respectively. Small, natural, and anthropogenic atmospheric ozone concentrations can increase the weathering and aging of materials such as plastics, paint, textiles, and mbber. For example, mbber is degraded by reaction of ozone with carbon—carbon double bonds of the mbber polymer, requiring the addition of aromatic amines as ozone scavengers (see Antioxidants Antiozonants). An ozone decomposing polymer (noXon) has been developed that destroys ozone in air or water (157). 

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 body excretes tritium with a biological half-life of 8—14 d (10.5 d average) (75), which can be reduced significantly with forced fluid intake. For humans, the estimated maximum permissible total body burden is 37 MBq (1 mCi). The median lethal dose (LD q) of tritium assimilated by the body is estimated to be 370 GBq (10 Ci). Higher doses can be tolerated with forced fluid intake to reduce the biological half-life. 

Median Lethal Dose (LD) The statistically derived single dose of a chemical that can be c.xpected to cause death in 50% of a given population of organisms under a defined set of experimental conditions. This figure has often been used to classify and compare toxicity among chemicals but its value for this purpose is doubtful. One commonly used classification of this kind is as follows ... 

Palytoxin (PTX) is one of the most potent marine toxins known and the lethal dose (LD q) of the toxin in mice is 0.5 Mg/kg when injected i.v. The molecular structure of the toxin has been determined fully (1,2). PTX causes contractions in smooth muscle (i) and has a positive inotropic action in cardiac muscle (4-6). PTX also induces membrane depolarization in intestinal smooth (i), skeletal (4), and heart muscles (5-7), myelinated fibers (8), spinal cord (9), and squid axons (10). PTX has been demonstrated to cause NE release from adrenergic neurons (11,12). Biochemical studies have indicated that PTX causes a release of K from erythrocytes, which is followed by hemolysis (13-15). The PTX-induced release of K from erythrocytes is depress by ouabain and that the binding of ouabain to the membrane fragments is inhibited by PTX (15). 

Skin Lethal dose (LD) is 1.7 g/person. Liquid does not injure skin but penetrates it rapidly. Immediate decontamination of smallest drop is essential. Vapor penetrates skin also. 

LD50 The lethal dose (LD) of a toxicant when taken orally or absorbed through the skin, which is lethal to fifty percent of the exposed lab animal population. 

Acute Lethality. The median lethal dose (LD g) of MCB to rainbow trout was estimated to be 1.8 ml/kg at 24 h. No mortalities were observed in any of the treated animals after this time. The 24 h LD50 value for CCI4 was estimated to be 4.75 ml/kg but, unlike fish treated with MCB, fish intoxicated with CCI4 continued to die throughout the entire 96 h observation period. 

Table 9. Highest non-lethal doses LD for the 4 cyclophosphathiazenes studied, (in mg/kg)...

Vinyl Compound Toxicity- Listed in Table 1 are the carcinogeneity, lowest toxic concn (TClq), lethal dose (LD), threshold limit value (TLV), avenue of body entry (Entry mode), and the appropriate refs for a number of vinyl compds. The primary toxic effects of most vinyl compds (except where lethality and car-cenogenic effect are noted) are those of skin irritation, corneal erosion, headache, nausea and vomiting... 

FIGURE 31.1 Modified Fibonacci dose escalation procedure, expressed as a ratio of the human dose to a reference dose in mice [e.g., the 10% lethal dose (LD o)]- Human studies typically start at one-tenth the murine dose, expressed on the basis of body surface area. If tolerated, the next dose is initially doubled, then the percentage change at each escalation step decreases. (Reproduced from Collins JM, Zaharko DS, Dedrick RL, Chabner BA. Cancer Treat Rep 1986 70 73 0.)... 

Chloroform in animals is known to cause acute toxicity similar to that in humans. The following lethal dose (LD) values have been reported ... 

When neither human data nor animal LC data were sufficient, NIOSH considered animal lethal dose (LD) data. NIOSH used the LD data to estimate the equivalent total dose to a 70 kg worker. The 30 min LC was estimated by dividing by 10 m, even though a worker breathing at a rate of 501min for 30 min would inhale 1.5 m of air. NIOSH determined a preliminary IDLH by dividing this estimated LC value by a factor of 10. 

The acute lethality of methanol is low based on animal testing via oral, dermal, and inhalation routes of exposure. The acute oral lethal dose (LD) observed in rats, rabbits, and monkeys range from 7mgkg (monkey) to 14.4 mg kg (rabbits). Acute dermal LD in rabbits have been reported as 20 mg kg and inhalation lethal concentrations ranged from 31 000 ppm (18 h exposure, rats) to 72 000 ppm (54 h exposure, mice). 

Dosages of a chemical can be described as a lethal dose (LD), effective dose (ED), or toxic dose (TD). The LD50 or LD50 is a common parameter used in toxicology. It represents the dose at which 50% of a test population would die when exposed to a chemical at that dose. Similarly, the lethal concentration (LC) is the concentration of a substance in air that will cause death. 

A survey of acute oral toxicity, as measured by the 50% lethal dose (LD j) test, demonstrated that of4461 colorants tested, only 44 had an LD-,j< 250 mg kg and that 3669 exhibited practically no acute toxicity (LD > 5 g kg ). The rest fell somewhere between these two levels. The evaluation of these colorants by chemical classification revealed that the most toxic ones were found among the diazo (mostly benzidine derivatives) and the cationic dyes. It is widely known that some general cationic compounds have toxic properties. Pigments and vat dyes by comparison were discovered to have extremely low acute toxicity - presumably due to their insolubility/very low solubility in water and in lipophilic systems. 

E. Quantal Dose-Response Relationships When the minimum dose required to produce a specified response is determined in each member of a population, the quantal dose-response relationship is defined (Figure 2-2). When plotted as the fraction of the population that responds at each dose versus the log of the dose administered, a cumulative quantal dose-response curve, usually sigmoid in shape, is obtained. The median effective (ED j,), median toxic (TD, ), and median lethal doses (LD j,) are extracted from experiments carried out in this manner. 

Oral toxicity. A liquid with a lethal dose (LD) of 50 or not more than 500 milligrams per kilogram, or a solid with an LDjq of not more than 200 mg/kg of the body weight of the animal. (LDjg is the single dose that will cause the death of 50% of a group of test animals exposed to it by any route other tlian inhalation.)... 

The ratio of the median lethal dose LD and the median effective dose gives the therapeutic index (TI = LD JED, which expresses how safe it is to use the dmg the higher the therapeutic index of a material is, the safer it is. In the case of diazepam (a common sedative), this value is around 100, while for digoxin (a cardiac glycoside), the TI is only 2-3, so the latter must be used very carefully. The actress Judy Garland died in 1969, at the age of 47, because she took too much Seconal, a sedative with small therapeutic index. 

Maximum air pollution concentrations —> Dose-response relationship/curve Median effective dose (ED J Dose-response relationship/curve Median lethal dose (LD g) Dose-response relationshipcurve Median lethal concentration (LCj ) Dose-response relationship/curve... 

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