Lethality

On the other hand, if the hazard is toxicity, process alternatives can be compared by assessing the mass of toxic material that would enter the vapor phase on release from containment, weighting the components according to their lethal concentration. 

Safrole from the Grignard reagent Keeping the apparatus from the above reaction, pour 60g of allylbromide into the sep funnel. As with the ingredients of the last procedure the allylbromide must be dried over sodium sulphate. This stuff is really nasty, use a mask at least or a fume cupboard if you can get access to one or fill the sep funnel outdoors. The fumes are invisible and pretty lethal -please be warned. 

The various barbiturates differ m the time required for the onset of sleep and m the duration of their effects All the barbiturates must be used only m strict accordance with instructions to avoid potentially lethal overdoses Drug dependence m some mdi viduals IS also a problem... 

The water quahty criteria for each species should be deterrnined from the Hterature or through experimentation when Hterature information is unavailable. Synergistic effects that occur among water quahty variables can have an influence on the tolerance a species has under any given set of circumstances. Ammonia is a good example. Ionized ammonia (NH ) is not particularly lethal to aquatic animals, but unionized ammonia (NH ) can be... 

As a class of compounds, the two main toxicity concerns for nitriles are acute lethality and osteolathyrsm. A comprehensive review of the toxicity of nitriles, including detailed discussion of biochemical mechanisms of toxicity and stmcture-activity relationships, is available (12). Nitriles vary broadly in their abiUty to cause acute lethaUty and subde differences in stmcture can greatly affect toxic potency. The biochemical basis of their acute toxicity is related to their metaboHsm in the body. Following exposure and absorption, nitriles are metabolized by cytochrome p450 enzymes in the Hver. The metaboHsm involves initial hydrogen abstraction resulting in the formation of a carbon radical, followed by hydroxylation of the carbon radical. MetaboHsm at the carbon atom adjacent (alpha) to the cyano group would yield a cyanohydrin metaboHte, which decomposes readily in the body to produce cyanide. Hydroxylation at other carbon positions in the nitrile does not result in cyanide release. 

The propensity of nitriles to release cyanide subsequent to metaboHsm is the basis of their acute toxicity. Nitriles that form tertiary radicals at their alpha carbon atoms (eg, isobutyronitrile, 2-methylbutyronitrile) are substantially more acutely lethal than nitriles that form secondary radicals at their alpha carbons (eg, butyronitrile, propionitnle). Cyanohydrins are acutely toxic because they are unstable and release cyanide quickly. Alpha-aminonitriles are also acutely toxic, presumably by analogy with cyanohydrins. 

Va2o-64, ALC (approx lethal concentration) Va2o-67, LC q. Va2o-64, -52, -88, ALD (approx lethal dose) Va2o-67, LD. See text for chemical names and stmctures. 

In laboratory tests, appHcation of DMAC to the skin of pregnant rats has caused fetal deaths when the dosages were close to the lethal dose level for the mother. Embryonal malformations have been observed at dose levels 20% of the lethal dose and higher. However, when male and female rats were exposed to mean DMAC concentrations of 31,101, and 291 ppm for 6 h per day over several weeks, no reproductive effects were observed (6). 

Since chloroacetyl chloride can react with water in the skin or eyes to form chloroacetic acid, its toxicity parallels that of the parent acid. Chloroacetyl chloride can be absorbed through the skin in lethal amounts. The oral LD q for rats is between 120 and 250 mg/kg. Inhalation of 4 ppm causes respiratory distress. ATLV of 0.05 ppm is recommended (28,41). 

Repeated exposures of animals to high (near-lethal) concentrations of vapors result in inflammation of the respiratory tract, as weU as degenerative changes in the Hver, kidneys, and heart muscle. These effects arise at concentrations far above those causing irritation. Such effects have not been reported in humans. The low odor threshold and irritating properties of acrylates cause humans to leave a contaminated area rather than tolerate the irritation. 

The lethal dose for 50% of the test animals, expressed ia terms of g of material per kg of body weight. 

Laboratory experiments using rodents, or the use of gas analysis, tend to be confused by the dominant variable of fuel—air ratio as well as important effects of burning configuration, heat input, equipment design, and toxicity criteria used, ie, death vs incapacitation, time to death, lethal concentration, etc (154,155). Some comparisons of polyurethane foam combustion toxicity with and without phosphoms flame retardants show no consistent positive or negative effect. Moreover, data from small-scale tests have doubtful relevance to real fine ha2ards. 

Toxicity. The lethal dose of Mgp2 to guinea pigs by ingestion is 1000 mg/kg (17). 

Toxicology and Handling. The lethal dose by ingestion in guinea pigs is 150 mg/kg body weight (13). The TLV for KHF2 is 2.5 mg /m ... 

Health and Safety Factors. Completely fluorinated alkanes are essentially nontoxic (16). Rats exposed for four hours to 80% perfluorocyclobutane and 20% oxygen showed only slight effects on respiration, but no pathological changes in organs. However, some fluorochemicals, especially functionalized derivatives and fluoroolefins, can be lethal. Monofluoroacetic acid and perfluoroisobutylene [382-21-8] are notoriously toxic (16). 

Approximate lethal concentration, inhalation by tats, 4 h exposure unless noted otherwise. 

The Du Pont HaskeU Laboratory for Toxicology and Industrial Medicine has conducted a study to determine the acute inhalation toxicity of fumes evolved from Tefzel fluoropolymers when heated at elevated temperatures. Rats were exposed to decomposition products of Tefzel for 4 h at various temperatures. The approximate lethal temperature (ALT) for Tefzel resins was deterrnined to be 335—350°C. AH rats survived exposure to pyrolysis products from Tefzel heated to 300°C for this time period. At the ALT level, death was from pulmonary edema carbon monoxide poisoning was probably a contributing factor. Hydrolyzable fluoride was present in the pyrolysis products, with concentration dependent on temperature. 

Properties. Properties of perfluoropropyl vinyl ether [1623-05-8] (PPVE), a colorless, odorless Hquid (mol wt 266) are shown in Table 1. Perfluoropropyl vinyl ether is an extremely flammable Hquid and bums with a colorless flame. It is significantly less toxic than hexafluoropropylene the average lethal concentration (ALC) is 50,000 ppm (10). 

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... 

Although DMF has led to iacreased embryo mortaUty ia pregnant animals at doses close to the lethal level for the pregnant animal, DMF exposures below the OSHA limits should not represent a ha2ard to pregnant workers as long as pmdent work practices are followed (4). 

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. 

Hydrogen chloride in air is an irritant, severely affecting the eye and the respiratory tract. The inflammation of the upper respiratory tract can cause edema and spasm of the larynx. The vapor in the air, normally absorbed by the upper respiratory mucous membranes, is lethal at concentrations of over 0.1% in air, when exposed for a few minutes. HCl is detectable by odor at 1—5 ppm level and becomes objectionable at 5—10 ppm. The maximum concentration that can be tolerated for an hour is about 0.01% which, even at these levels, causes severe throat irritation. The maximum allowable concentration under normal working conditions has been set at 5 ppm. 

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