Toxic components

Health and Safety Factors. Sulfur hexafluoride is a nonflammable, relatively unreactive gas that has been described as physiologically inert (54). The current OSHA standard maximum allowable concentration for human exposure in air is 6000 mg/m (1000 ppm) TWA (55). The Underwriters Laboratories classification is Toxicity Group VI. It should be noted, however, that breakdown products of SF, produced by electrical decomposition of the gas, are toxic. If SF is exposed to electrical arcing, provision should be made to absorb the toxic components by passing the gas over activated alumina, soda-lime, or molecular sieves (qv) (56). 

A toxic component of braken fern, perhaps either quercetin (105) or ptaquiloside, a glucoside (106), has a mixed history of carcinogenicity. It is sometimes impHcated in an increased incidence of bladder cancer in animals and esophageal cancer in humans. Multiple other dietary components seem to either promote or interfere with its action, and the significance of braken fern in human carcinogenesis remains unproven. 

A. Reife, "Reduction of Toxic Components and Wastewaters ofDisperse Blue 79," 41 st Southeast RegionalMmerican Chemical Society Meeting, Raleigh, N.C., Oct. 9-11,1989. 

Aceording to Okanishi, the toxic components of G. elegans are identical with those of G. sempervirens. 

Purification of poloxamers has been extensively investigated due to their use in medical applications, the intention often being to remove potentially toxic components. Supercritical fluid fractionation and liquid fractionation have been used successfully to remove low-molecular weight impurities and antioxidants from poloxamers. Gel filtration, high-performance liquid chromatography (HPLC), and ultrafiltration through membranes are among the other techniques examined [5]. 

The inert gas is added under pressure to the system to be purged. This is then vented or purged to the atmosphere, usually more than one cycle of pressurization followed by venting is necessary to drop the concentration of a specific flammable or toxic component to a pre-established level. 

The biochemistry or mode of action of pyrethrum is not as well known as its chemistry. There are several theories of the toxic action of pyrethrum. Lauger et al. (26) consider that a highly effective contact insecticide must possess a toxic component (toxaphore) and must have groups attached which absolutely insure pronounced lipid solubility. They consider in the case of pyrethrins that in the cyclopro-... 

Inhibition of tomato and barley plants growing in soils infested with Centaurea repens (knapweed) was reported by Fletcher and Renney (38). A toxic component was isolated in highest concentration from the foliage of knapweed. The inhibitor was considered to be an indole alkaloid or auxin precursor because of its ultraviolet absorption spectrum and the positive reactions obtained with Salkowski and Ehrlich reagents. The presence of the inhibitor was considered to explain partially the rapid establishment of Centaura spp. in almost pure stands. 

Although it is possible to identify a group of particularly toxic components in venom, it should be noted that the venoms are complex mixtures of components, many of which are synergistic. Muscle damage is particularly severe if myotoxic activity is combined with hemorrhagic activity. In this case, muscle regeneration is impaired, because the regenerating tissue is rendered anoxic at a time of intense metabolic activity. 

The presence of toxins in C. geographus venom which block the response of vertebrate skeletal muscle to direct electrical stimulation was first detected by Endean et al. (14). A toxic component which reversibly blocked the generation of action... 

It is generally agreed that the contact-insecticidal activity of the DDT type of compound depends on at least one toxic component and the CC13 group or some other lipoid-soluble group for penetration. Beyond this point, there is a lack of agreement as to the exact mechanism by which the contact insecticides exert their action. 

There are several theories concerning the mechanism by which the toxic component of a contact insecticide exerts its action. The toxicity has been credited to the condensed chlorobenzene system, which is also lipophilic in character (70). 

The design of such cytotoxic antibodies is conceptually simple attach a toxic substance or a mediator of toxicity to the appropriate monoclonal and you have a magic bullet that can find and eliminate the one-in-a-billion cells that have the requisite marker (Figure 21.1). The antibody provides the recognition and binding capacity, while the associated toxic component effects cellular alterations leading to cell death (Pastan et al., 2006). 

In 1986, domestic consumption of copper in the United States was 2.14 million metric tons, and mine production was 1.14 million metric tons, mostly from mines in Arizona, New Mexico, and Michigan. The major copper deposits in the United States are of hydrothermal origin and are uniformly distributed in fractures or veins (ATSDR 1990). Copper is the major toxic component in streams impacted by active placer mines (Buhl and Hamilton 1990). About 60% of copper metal is eventually recycled in 1986, smelting of scrap copper produced an additional 0.9 million metric tons of copper. Also in 1986, 1.1 million tons of copper were imported into the United States, mostly from Canada, Chile, Peru, and Mexico (ATSDR 1990). 

Oikari, A. and J. Kukkonen. 1988. Acclimatization of roach, Rutilus rutilus (L.), to toxic components of kraft pulp mill effluents. Ecotoxicol. Environ. Safety 15 282-288. 

Earle et al. [1.89] showed, that the RM in the product Pedvax HIB TM did not change during storage at 2-8 °C for 24 months if the stoppers were steam-sterilized, vacuum dried for 6 h and finally dried at +143 °C for 4 h. If the vials were closed with stoppers which had not been dried, the RM increased in 12 months to approx. 5.3 %. Danielson [1.90] warned against toxic components which could diffuse or migrate from the stopper to the product. A protective coating does not avoid the extraction of these substances, but Teflon coating is better than none. 

The oxidation process in a wastewater containing small amounts of a toxic component A and a high concentration of a non-toxic easily biodegradable pollutant B involves three types of reactions ... 

Single-ring aromatics. Aromatic constituents are characterized by the presence of rings with six carbon atoms and are considered to be the most acutely toxic component of crude oil constituents because of their association with chronic and carcinogenic effects. Many low-molecular-weight aromatics are also soluble in water, increasing the potential for exposure to aquatic resources. 

Fugitive air emissions of volatile components released during hydrotreating may also be toxic components. These include toluene, benzene, xylenes, and other volatiles that are reported as toxic chemical releases under the EPA Toxics Release Inventory. 

Abstract This chapter discusses the characteristics of membrane concentrate, and the relevance that the concentrate has on the method of disposal. Membrane concentrate from a desalination plant can be regarded as a waste stream, as it is of little or no commercial benefit, and it must be managed and disposed of in an appropriate way. It is largely free from toxic components, and its composition is almost identical to that of the feed water but in a concentrated form. The concentration will depend on the type of desahnation technology that is used, and the extent to which fresh water is extracted from the brine. Based on the treatment processes that are used, a number of chemicals may also be present in the concentrate, albeit in relatively small quantities. 

Chapter 14 Toxic Components of Food Packaging Materials... 

Gyrometrin toxin is produced by the false morel (Gyromitra esculenta), a short-stalked mushroom with a brain-like cap of dark brown color. Fruiting bodies of this mushroom appear mostly in spring and are valued as edible, even as delicacies. While many people consume the mushroom without any troubles, others become ill, some of them severely. It has been shown that the toxin content may vary with growth conditions, such as altitude and temperature. More probably, however, the variation is caused by differences in handling or cooking as the toxic components are volatile. The toxin has been detected in cooked, frozen, and dried specimens. 

Separation and quantitation of the toxic components of A. muse aria and related mushrooms can be achieved by HPLC, or by TLC using ninhydrine and heating for detection. With ninhydrine, muscimol develops a yellow spot and has a limit of detection of 0.1 pg. 

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