1 monoxide toxic action

In the evaluation of toxic characteristics of an inhalable environmental chemical (e.g., carbon monoxide, volatile chemical, or aerosol/particulate), determination of acute inhalation toxicity is an initial study step. It provides information on health hazards likely to arise from short-term exposure by inhalation. Data from an acute test help to establish a dose regimen in subchronic (and other) studies, and may provide additional information on a chemical s mode of toxic action. 

Carbon monoxide was not employed during the war of 1914-18 as a war gas, but its toxic action has been established on several occasions in the field. 

Toxic substances are concentrated in special tissues. Certain substances achieve a maximal concentration at the site of their action (e.g. carbon monoxide exhibits a high affinity to haemoglobin) some other substances, on the other hand, are concentrated in certain organs where they are bound in different forms, thus forming a reservoir with a high content of the substance (depot). The site of their own toxic action may be, however, different from the accumulating organ. 

Mankind encountered the effects of carbon monoxide as far back as prehistoric times. It is the most common poison with a suffocation action. It is second to carbon dioxide with respect to the amounts of industrial emissions. Carbon monoxide toxicity is due to its affinity to haemoglobin. This affinity is higher by a factor of 200 than that of oxygen. Haemoglobin... 

The next relevant discovery was made in 1910, when it was noted that some enzymes are blocked by substances whose molecular structure resembles that of the normal substrates. Thus amylase, which normally hydrolyses starch, is inhibited by glucose (see Section 9.1). Again, malonic acid 9.3) competitively inactivates the enzyme succinic dehydrogenase by displacing the normal substrate, succinic acid 9.4), from the enzyme (Quastel and Wooldridge, 1927). A similar phenomenon in physiology is the toxic action of carbon monoxide... 

Godish, T, 2003. Air Quality, fourth ed. Lewis Books, Boca Raton, FL. Goldbaum, L.R., Ramirez, R.G., Absalon, K.B., 1975. What is the mechanism of carbon monoxide toxicity Aviat. Space Environ. Med. 46, 1289-1291. Goldbaum, L.R., Orellano, T, Dergal, E., 1976. Mechanism of the toxic action of carbon monoxide. Ann. Clin. Lab. Sci. 6, 372-376. 

SIPs are intended to prevent air pollution emergency episodes. The phms are directed toward preventing excessive buildup of air pollutants tliat me known to be harmful to the population and the enviroiunent when concentrations exceed certain limits. The compounds affected under the implementation plans are sulfur dioxide, particulate matter, ctirbon monoxide, nitrogen dioxide, and ozone. A contingency plan, which will outline the steps to be taken in tlie event tliat a particular pollutant concentration reaches tlie level at wliich it can be considered to be hannful, must be included in each implementation plan. The implementation plans are solely based on tlie continuous emission of tlie previously stated air pollutants. They do not mandate any actions to be taken in tlie event of an accidental toxic release. 

In addition, other chemicals such as a-adrenergic blocking agents like chlorpromazine (O Flaherty and Thomas 1982 Way and Burrows 1976) or oxygen (Burrows et al. 1973 Sheehy and Way 1968) may be used to enhance the protective action of other antidotes. However, the mechanism of their action is not well understood. Further research for a potent and safe antidote, particularly among smoke inhalation victims who have carbon monoxide poisoning, to mitigate cyanide toxicity is desirable. 

In an animal, a xenobiotic substance may be bound reversibly to a plasma protein in an inactivated form. A polar xenobiotic substance, or a polar metabolic product, may be excreted from the body in solution in urine. Nonpolar substances delivered to the intestinal tract in bile are eliminated with feces. Volatile nonpolar substances such as carbon monoxide tend to leave the body via the pulmonary system. The ingestion, biotransformation, action on receptor sites, and excretion of a toxic substance may involve complex interactions of biochemical and physiological parameters. The study of these parameters within a framework of metabolism and kinetics is called toxicometrics. 

Although the toxicity of nickel carbonyl is five times as great as carbon monoxide, the available literature data (Armit, 31) indicate that dicobalt octacarbonyl is not as toxic, probably because of its very low vapor pressure. Apparently no investigation has been made into the physiological action of cobalt hydrocarbonyl. It is stated to have an almost intolerable vile odor and its very high vapor pressure is certainly good reason to be extremely cautious in its use. 

The French physiologist Claude Bernard (1857) and the British physiologist Haldane (1895a) inferred that the toxicity of CO was caused by its interaction with hemoglobin. In his review of carbon monoxide, Lilienthal (1950) writes It has been said many times that the effect of CO on man may be attributed to two actions and, in essence, to these two actions alone (a) occupation of the Hb molecule by CO, with a resultant decrease in the O2 transport capacity of the blood and (b) alteration of 02Hb dissociation... 

SAFETY PROFILE Most carbonyls are highly toxic. The toxicity of carbonyls depends in part, but not always endrely, on their ready decomposition, which releases carbon monoxide. Symptoms are due in part to carbon monoxide and in part to the direct irritating action of the carbonyl. See specific carbonyl in question. Many carbonyl metals ignite spontaneously in air, some with a delay period. Others are moderate fire and explosion hazards when exposed to heat or flame. Carbonyls of alkali metals are potentially explosive. Hypergolic reaction... 

Carbon Monoxide A colorless, tasteless gas, CO. Highly flammable (liquid autoignition point, 609°C) and toxic. Found in automobile exhaust gases and is a major air pollutant. Manufactured from coke by action of oxygen and carbon dioxide or steam. Used in organic S5mthesis, synthetic fuels, and metallurgy. 

Methylene Chloride (MC) is primarily an inhalation hazard. The principal acute hazardous effects are the depressant action on the central nervous system, possible cardiac toxicity and possible liver toxicity. The range of CNS effects are from decreased eye/hand coordination and decreased performance in vigilance tasks to narcosis and even death of individuals exposed at very high doses. Cardiac toxicity is due to the metabolism of MC to carbon monoxide, and the effects of carbon monoxide on heart... 

In summary, then, the primary pollutants from the internal combustion engine of an automobile are carbon monoxide, lower hydrocarbons, and nitric oxide. These are dangerous, toxic materials in themselves but are just the beginning of the story. The action of sunlight on the primary pollutants is what really still makes photochemical smog one of the most difficult problems facing humankind as we begin the twenty-first century. 

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