Threats

The ground bed, for example, of the Russian railway roads used in very tough operating and natural conditions, its defects and deformations present a real threat to the safe trains running and reduce the passage capacity of the railway lines. 

Intrinsic bioremediation is becoming an acceptable option in locations where the contaminated groundwater poses Htde threat to environmental health. Nevertheless, although intrinsic bioremediation is appealingly simple, it may not be the lowest cost option if there are extensive monitoring and documentation costs involved for several years. In such cases it may well be more cost effective to optimize conditions for biodegradation. 

Skin contact with methanol may present a greater health threat than skin contact with gasoline and diesel fuel and is being evaluated. 

Conserva.tlon, Because the most common conservation problem with metal objects occurs when corrosion processes form a threat to the safety of the object or disfigure its appearance to an unacceptable degree (130,131), many conservation treatments are intended to stabilize the corrosion processes and to remove aesthetically displeasing corrosion cmsts. The latter requkes a great deal of thought and discussion as to when a corrosion layer ceases to be a deskable patina and becomes unacceptable. 

Considerable concern has been raised over the carcinogenic potential of 2,4-D. However, the World Health Organization (WHO) has evaluated the environmental health aspects of this chemical and concluded that 2,4-D posed an insignificant threat to the environment. They did indicate, however, that... 

Aromatic Hydrocarbons. These are the most toxic of the hydrocarbons and inhalation of the vapor can cause acute intoxication. Benzene is particularly toxic and long-term exposure can cause anemia and leukopenia, even with concentrations too low for detection by odor or simple instmments. The currendy acceptable average vapor concentration for benzene is no more than 1 ppm. PolycycHc aromatics are not sufftcientiy volatile to present a threat by inhalation (except from pyrolysis of tobacco), but it is known that certain industrial products, such as coal tar, are rich in polycycHc aromatics and continued exposure of human skin to these products results in cancer. 

Vimses are obligate intracellular parasites. They only exhibit activity by infecting other living organisms, thus they are not a practical concern in industrial microbiological fields. The exception is where viral contamination of the product or process represents a threat of transmission of disease. Microscopic insects and protozoans are also not addressed in this article (see Insectcontroltechnology). 

Most iron salts and compounds may be safely handled following common safe laboratory practices. Some compounds are irritants. A more serious threat is ingestion of massive quantities of iron salts which results in diarrhea, hemorrhage, fiver damage, heart damage, and shock. A lethal dose is 200 250 mg/kg of body weight. The majority of the victims of iron poisoning are children under five years of age. 

Hydrolysis is a significant threat to phosphate ester stabiHty as moisture tends to cause reversion first to a monoacid of the phosphate ester ia an autocatalytic reaction. In turn, the fluid acidity can lead to corrosion, fluid gelation, and clogged filters. Moisture control and filtration with Fuller s earth, activated alumina, and ion-exchange resias are commonly used to minimise hydrolysis. Toxicity questions have been minimised ia current fluids by avoiding triorthocresyl phosphate which was present ia earlier natural fluids (38). 

The uses of spunbonded fabrics as coverstock in diapers and other personal absorbent devices will most likely remain unchallenged for the near term. Virtually any other nonwoven production method appears to be at a cost disadvantage opposite spunbonded polypropylene. There have been composite products developed from meltblown and spunbonded combinations, where areas of either improved hydrophobicity or hydrophilicity are desired. These products can be produced on-line at relatively low additional cost and offer high value to diaper manufacturers. Any competitive threat is likely to come from advances in film technology such as large improvements in perforated film used in segments of absorbent product appHcations, particularly sanitary napkins. 

Every developed nation has experienced product tampering incidents. The principal difference between domestic and foreign incidents is the motive of the tamperers. In the United States, typically random tampering without prior threat occurs whereas outside the United States, extortion prior to injury occurs, with money appearing to be the primary motive. Most developed nations are either implementing or modifying their rules on the use of tamper-evident packaging. Some features as they are used in the United States would have to be modified or the use of a secondary feature required to meet the standards of various other countries. 

The pharmacist or physician can report any problems experienced with dmg products and medical devices. In cases where the PDA and/or manufacturer finds that a marketed product constitutes an actual or potential threat to the safety and welfare of the pubhc, that product must be withdrawn from the marketplace, ie, recalled. Several classes of recalls exist, depending on the relative danger that the product exhibits. C/ass I dmgs pose a serious health threat and may require withdrawal at the consumer level C/ass II dmgs pose a possible or potential health problem that usually means withdrawal at the pharmacy or wholesaler levels and C/ass III dmgs may present a remote hazard to health and safety. 

Implantable valves, particularly mechanical valves which continue to encroach on tissue valves, are unique. Methods such as valvuloplasty, mitral valve repair, or use of ultrasound are unlikely to reduce the number of valve replacements into the twenty-first century. Valve selection remains in the hands of the surgeon because of the critical nature of the procedure. If anything goes wrong, the result can be catastrophic to the patient. Cost of a valve, from 3000— 4000, is a relatively small part of the cost of open-heart surgery which can mn as high as 30,000. Growth of the cardiovascular valve market has slowed in the United States with the decline of the threat of rheumatic fever. 

The threat of accidental misuse of quaternary ammonium compounds coupled with potential harmful effects to sensitive species of fish and invertebrates has prompted some concern. Industry has responded with an effort to replace the questionable compounds with those of a more environmentally friendly nature. Newer classes of quaternaries, eg, esters (206) and betaine esters (207), have been developed. These materials are more readily biodegraded. The mechanisms of antimicrobial activity and hydrolysis of these compounds have been studied (207). AppHcations as surface disinfectants, antimicrobials, and in vitro microbiocidals have also been reported. Examples of ester-type quaternaries are shown in Figure 1. 

Radiation Dosimetry. Radioactive materials cause damage to tissue by the deposition of energy via their radioactive emissions. Thus, when they are internally deposited, all emissions are important. When external, only those emissions that are capable of penetrating the outer layer of skin pose an exposure threat. The biological effects of radiation exposure and dose are generally credited to the formation of free radicals in tissue as a result of the ionization produced (17). 

Where technology is central to competitive success, such a breakdown in the management of technology can become a serious threat to long-term corporate performance. This situation has created a challenging environment for technology leaders as they stmggle to reestabUsh their credibility and reassert their leadership in the business. 

Maintaining external awareness. Beyond understanding customer needs, a set process monitors external threats and opportunities from a variety of sources. 

When the design temperatures are significantly below ambient temperature, the primary threat to tank integrity is failure of the material by britde fracture. The tank design codes usually provide thorough treatment of this topic to prevent catastrophic failure. Additionally, there is the consideration of corrosion allowance, defined as extra thickness added beyond that required for strength. Corrosion allowance is not discussed herein. 

Freshwater is now scarce in many regions of the world, resulting in severe ecological degradation, limits on agricultural and industrial production, threats to human health, and increased potential for international conflict. 

Terphenyls in heat-transfer appHcations are used in relatively smaller quantities with negligible release to the environment. They are sufficiently biodegradable so as not to constitute an environmental threat (56,57). Some properties important for environmental considerations are summari2ed in Table 7. 

Armor. Sihcon carbide is used as a candidate in composite armor protection systems. Its high hardness, compressive strength, and elastic modulus provide superior baUistic capabihty to defeat high velocity projectile threats. In addition, its low specific density makes it suitable for apphcations where weight requirements are critical (11). 

Exposure to metal carbonyls can present a serious health threat. Nickel carbonyl is considered to be one of the most poisonous inorganic compounds. However, the toxicological information available on metal carbonyls is restricted to the mote common, commercially important compounds such as Ni(CO)4 and Ee(CO). Other metal carbonyls are considered potentially dangerous, especially ia the gaseous state, by analogy to nickel and iron carbonyls. Data concerning toxicological studies on a few common metal carbonyls are Hsted ia Table 6 (185). Additional toxicity data are OSHA personal exposure limits (PEL) for Ee(CO) this is 8 h at 0.1 ppm, whereas for the much more toxic Ni(CO)4 it is 8 h at 0.001 ppm, with a toxic concentration TCLq low (of 7 mg/m ) for human inhalation. 

Olefin polymerization catalysts are unique in their utilization of supported catalysts in that the catalysts that have been developed are so highly active that the spent catalysts are intentionally left in the polymer where, at the extremely low parts per million concentrations used, they pose no threat to the properties of the polymer or to the well-being of the end user. 

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