Toxicant decomposition

Over the years animal studies have repeatedly shown that perfluorinated inert fluids are nonirritating to the eyes and skin and practically nontoxic by ingestion, inhalation, or intraperitoneal injection (17,22). Thermal degradation can produce toxic decomposition products including perfluoroisobutene which has a reported LC q of 0.5 ppm (6 hr exposure in rats) (31). This decomposition generally requires temperatures above 200°C. 

In some appHcations the high heat stabiHty of the micropowder can be utilized over a reasonably wide temperature range. A maximum service temperature is normally 260°C, provided the crystalline melting point is between 320 and 335°C. Exposure above 300°C leads to degradation and possible evolution of toxic decomposition products. 

LLDPE can present a certain health hazard when it bums, since smoke, fumes, and toxic decomposition products are sometimes formed in the process. Exposure to burning LLDPE can cause irritation of the skin, eyes, and mucous membranes of the nose and throat due to the presence of acrolein and formaldehyde (81). Toxicity of LLDPE pyrolysis products depends on temperature, heating rate, and the sample size (82—84). 

In particular, PB and PMP are inert materials and usually present no health hazard. PMP is employed extensively for a number of medical and food packaging appHcations. Several grades conform to FDA regulations and to the health standards of other countries. Flammability of polyolefin resins is equal to that of PP, around 2.5 cm /min (ASTM D635). However, during combustion or pyrolysis, smoke, fumes, and toxic decomposition products are formed and can pose a health hazard. 

For many applications it is found that the technique of free sintering is quite satisfactory. This simply involves heating the preform in an oven at about 380°C for a time of 90 minutes plus a further 60 minutes for every 0.25 in (0.65 cm) thickness. For example a sample 0.5 in (1.25 cm) thick will require sintering for 3.5 hours. The ovens should be ventilated to the open air to prevent toxic decomposition products accumulating in the working area. 

Bromine compounds are often used as flame retardant additives but 15-20ptsphr may be required. This is not only expensive but such large levels lead to a serious loss of toughness. Of the bromine compounds, octabromo-diphenyl ether has been particularly widely used. However, recent concern about the possibility of toxic decomposition products and the difficulty of finding alternative flame retarders for ABS has led to the loss of ABS in some markets where fire retardance is important. Some of this market has been taken up by ABS/PVC and ASA/PVC blends and some by systems based on ABS or ASA (see Section 16.9) with polycarbonates. Better levels of toughness may be achieved by the use of ABS/PVC blends but the presence of the PVC lowers the processing stability. 

Ethylenethiourea (ETU) is a toxic decomposition product/metabolite of alky-lenebis(dithiocarbamates). This compound could be generated during processing of treated crops at elevated temperature. Different chromatographic methods to determine the residue levels of ETU have been published. After extraction with methanol, clean-up on a Gas-Chrom S/alumina column and derivatization (alkylation) with bro-mobutane, ETU residues can be determined by GC with a flame photometric detector in the sulfur mode. Alternatively, ETU residues can also be determined by an HPLC method with UV detection at 240 nm or by liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/tandem mass spectrometry (LC/MS/MS) (molecular ion m/z 103). ... 

V-series nerve agents Extremely toxic decomposition products, including S-[2-dialkylaminoethyl] alkylphosphonothioic acids and alkyl pyrophosphonates, may be... 

Nitrogen vesicants These agents are essentially insoluble in water. They will decompose on standing in water but form neurotoxic products. Some of these toxic decomposition products can last for extended periods. 

Unprotected feedstock (e.g., hay or grain) should be destroyed. Leaves of forage vegetation could still retain sufficient vesicant agent, or toxic decomposition products, to produce effects for several weeks post release, depending on the level of contamination and the weather conditions. 

Heat from a fire will increase the amount of agent vapor in the area. A significant amount of the agent could be volatilized and escape into the surrounding environment before it is consumed by the fire. Actions taken to extinguish the fire can also spread the agent. Combustion or hydrolysis of arsenic vesicants will produce volatile, toxic decomposition products (see Section 4.4.5). 

Remove all clothing and personal effects and decontaminate with soap and water. Do not use bleach or detergents containing bleach as they may interact with agents to produce toxic decomposition products. 

Liquid chromatographic techniques have been frequently employed for the separation and identification of the toxic decomposition products of synthetic dyes. Thus, the amount of aromatic amines formed from azo dyes in toys has been determined. The chemical structures of the dyes included in the investigation are listed in Fig. 3.60. The dyes were... 

Toxic Decomposition Products In situations where the content of the API in a drug product is well above 90% as indicated above, the formation of toxic degradation products within the shelf life (which may cause untoward effects to the patients) may warrant the reassignment of a different expiration date or recall of the drug product in question. Consequently, the pharmaceutical industry is often concerned with both the amount as well as the nature of the degradation products. The formation of toxic products is particularly problematic with protein drugs which may maintain therapeutic activity after deliberate modification or pertubation of molecular structure in a domain removed from that associated with therapeutic activity... 

Chlorinated biphenyls Therminol, Monsanto liquid 50-600 0 toxic decomposition products... 

Caution. The following compounds are very air-sensitive, have unpleasant odors and are to some degree toxic. Decomposition may lead to the formation of oxide clouds of a dangerous, choking, particle size. Extreme care must be taken in the handling and, in particular, in the disposal of waste material. 

HDPE can present health hazards when it burns. Heavy smoke, fumes, or potentially toxic decomposition products can result from incomplete combustion. Large-scale fire testing has shown that the products formed from HDPE present no greater hazard than those from cellulostc materials, wood, fell, or rubber. 

LLDPE can present a certain health hazard when it burns, since smoke, fumes, and toxic decomposition products aie sometimes formed in the process. 

SAFETY PROFILE Poison by intravenous and intraperitoneal routes. Moderately toxic by ingestion. A human skin irritant. This material yields hydrogen sulfide on decomposition. A death has been attributed to the absorption of toxic decomposition products from the use of this material in a hair permanent-waving solution. When heated to decomposition it emits toxic fumes of SOx and Na20. See also SULFIDES and MERCAPTANS. 

Peroxidases Used as an enzymatic rinse process after reactive dyeing, oxidative splitting of hydrolysed reactive dyes on the fibre and in the liquor, providing better wet fastness, decolourised waste water and potentially toxic decomposition compounds (aromatic nitro-compounds)... 

In all the above-mentioned cases, the active component itself had to be determined. However, polarography often serves to determine toxic decomposition products or reaction intermediates in pharmaceutical synthesis. Besides the presence of codeinone in dihydrocodeinone [189], one can detect the presence and amount of toxic ketones in chloramphenicol [221] or of papaveraldine in papaverine [222]. 

This is an irreversible system, and the reaction does not depend on transport from a hotter to a colder zone. Gas phase nucleation is reduced, and the reaction temperature is low (300-500°C). The hydrogen passivation occurs, but still this effect may be partially alleviated by substitution of an alkyl chalcogenide to avoid the hydrogen selenide. Alkylselenium compounds originally were used to avoid the very toxic H2Se. The criteria (e.g., toxicity, decomposition into stable products) for selection of these alternative precursors have been reviewed . 

There are certain active substances which, having decomposed in dosage forms, have toxic decomposition products (Paal 1990b). It is advisable to specify limit tests, even in dosage forms, for these degradation products when such applications are filed. 

Carbonyl sulfide is a flammable gas, and may be explosive or spontaneously flammable in air under the right conditions. Vapors may ignite at distant ignition sources and flash back. When exposed to fire, humidity, or strong alkalis, carbonyl sulfide may form the toxic decomposition products carbon monoxide and hydrogen sulfide gas. In the presence of strong oxidizers, carbonyl sulfide presents a fire or explosion hazard. Carbonyl sulfide has a vapor density of 2.1 and is therefore heavier than air. Cylinders or tank cars containing carbonyl sulfide may rupture violently or rocket under fire conditions. 

Although many refrigerants, propellants and anaesthetics are non-toxic, in the presence of a flame or on contact with very hot surfaces, phosgene may be produced as one of the toxic decomposition products. The chlorofluorocarbons, CCI3F (CFC-11), CQjF (CFC-12) and CjCljF, (CFC-114), when exposed to a gas flame, all generate phosgene as one of the... 

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