Toxic substances toxicity

As discussed in detail in Chapter 6, toxicology refers to the detrimental effects of substances on organisms. Substances with such effects are called toxic substances, toxicants, or poisons. Whether or not a substance is toxic depends on the amount to which an organism is exposed and the manner of exposure. Some substances that are harmless or even beneficial at low levels are toxic at higher levels of exposure. 

USEPA 1985. U.S. Environmental Protection Agency. Office of Toxic Substances. Toxic Substances Control Act Test Guidelines. 50 FR 39252... 

Hansen SR, Janssen C, Beasley VR. Denatonium benzoate as a deterrent to ingestion of toxic substances toxicity and efficacy. Vet Hum Toxicol 1993 35(3) 234-236. 

Pesticides Tank Truck Hazard Class 6 (toxic substance) Toxic exposure to people located along transportation routes Higher... 

Water on and beneath the surface of the geosphere plays a strong role in pollution and the distribution of toxic substances. Toxic substances from wastes improperly disposed to the geosphere can leach into groundwater and contaminate water supplies. Radioactive radium resulting from the decay of uranium in aquifer formations has caused some groundwater sources of drinking water to be abandoned. 

Toxic substances. Toxic chemicals should be handled with care, and only the minimum quantities needed for the work should be present in the work area. The containers should be suitably marked with appropriate labels (see Appendix 3). In storage, segregate toxic substances from acids and oxidizing... 

Combustion in an incinerator is the only practical way to deal with many waste streams.This is particularly true of solid and concentrated wastes and toxic wastes such as those containing halogenated hydrocarbons, pesticides, herbicides, etc. Many of the toxic substances encountered resist biological degradation and persist in the natural environment for a long period of time. Unless they are in dilute aqueous solution, the most effective treatment is usually incineration. 

CH2CI2. A colourless liquid with a chloroform-like odour b.p. 4I°C. Prepared by heating chloroform with zinc, alcohol and hydrochloric acid manufactured by the direct chlorination of methane. Decomposed by water at 200°C to give methanoic and hydrochloric acids. Largely used as a solvent for polar and non-polar substances, particularly for paint removal (30%), dissolving cellulose acetate and degreasing (10%). It is more stable than carbon tetrachloride or chloroform especially towards moisture or alkali. It is somewhat toxic. U.S. production 1981 280000 tonnes. 

Because of its toxicity, it is often necessary to be able to detect arsenic when present only in small amounts in other substances. 

Chloroform undergoes oxidation to the very poisonous phosgene upon exposure to light and air. Commercial specimens are therefore stored in brown bottles and contain 1-2 per cent, of alcohol the latter converts the toxic phosgene into the harmless substance diethyl carbonate ... 

The preparation of these compounds in the laboratory is not recommended and is rarely worth while because of the cheapness of the commercial products. Dimethyl sulphate is a heavy liquid, boiling at 188-6°, and is practically without odour. The vapour is highly poisonous and the substance should only be used in a fume cupboard with a good draught. The liquid itself is readily absorbed through the skin, with toxic results. 

Talaromycin A (a toxic substance produced by a fungus that grows on poultry house litter)... 

DDT resistant insects have the ability to convert DDT to a less toxic substance called DDE The mass spectrum of DDE shows a cluster of peaks for the molecular ion at m/z 316 318 320 322 and 324 Suggest a reasonable structure for DDE... 

Tests with animals have revealed that dioxin is one of the most toxic substances known Toward mice it IS about 2000 times more toxic than strychnine and about 150 000 times more toxic than sodium cyanide Fortunately however available evidence in dicates that humans are far more resistant to dioxin than are test animals and so far there have been no human fatalities directly attributable to dioxin The most prominent short term symptom seen so far has been a severe skin disorder known as chloracne Yet to be determined is the answer to the question of... 

Since feeds contain other substances than those required by the animals of interest, studies have also been conducted on antinutritional factors in feedstuffs and on the use of additives. Certain feed ingredients contain chemicals that retard growth or may actually be toxic. Examples are gossypol in cottonseed meal and trypsin inhibitor in soybean meal. Restriction on the amount of the feedstuffs used is one way to avoid problems. In some cases, as is tme of trypsin inhibitor, proper processing can destroy the antinutritional factor. In this case, heating of soybean meal is effective. 

Registry of Toxic Effects of Chemical Substances (RTECS) On-Liae Database. National Library of Mediciae, Bethesda, Maryland. 

D. V. Sweet, Kegisty of Toxic Tffects of Chemical Substances, 1986 ed., U.S. Dept, of Health and Human Services, National Institute for Occupational Safety and Health, Cincinnati, Ohio. 

H. S. Christensen and T. Lugiubyl, eds., Registy of Toxic Effects of Chemical Substances, U.S. Dept, of Health, Education, Welfare, RockviUe, Md., 1975. 

Compatibihty of acetone with other materials should be carefliUy considered, especially in disposal of wastes. It reacts with chlorinating substances to form toxic chloroketones, and potentially explosively with some peroxy compounds and a number of oxidizing mixtures. Mixed with chloroform, acetone will react violently in the presence of bases. Other incompatibilities ate Hsted in the Sax handbook (53). 

There are three types of TAP emissions continuous, intermittent, and accidental. Both routine emissions associated with a batch process or a continuous process that is operated only occasionally can be intermittent sources. A dramatic example of an accidental emission was the release of methyl isocyanate [624-83-9] in Bhopal, India. As a result of this accident, the U.S. Congress created Tide III, a free-standing statute included in the Superfund Amendments and Reauthorization Act (SARA) of 1986. Title III provides a mechanism by which the pubHc can be informed of the existence, quantities, and releases of toxic substances, and requires the states to develop plans to respond to accidental releases of these substances. Eurther, it requires anyone releasing specific toxic chemicals above a certain threshold amount to aimuaHy submit a toxic chemical release form to EPA. At present, there are 308 specific chemicals subject to Title III regulation (37). 

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