Environmentally unavailable

A wide variety of animal species are subjected to the administration of drugs during their lifetime.The various animal species can encounter drugs and other dietary additives by different routes and this is dependent on the environment in which they are kept. Intensively reared animals tend to have considerable consistency in the components of their diets and thus are much less likely to encounter the range of naturally produced compounds that extensively produced animals encounter. The desire for less expensive dietary constituents and increased efficiency of use has induced feed manufacturers and producers to add enzyme supplements to diets of most farmed animals to reduce the negative effects of indigestible dietary carbohydrates, refactory proteins and unavailable minerals such as phosphorus. This use of dietary additives to improve nutrient utilization and environmental consequences of feeding animals intensively has been the subject of intense research activity in the last five years. " The... 

California Steel Industries, Inc., located in Fontana, CA, reclaimed wastes to increase profits and address water use issues. The facility, a steel mill, is situated in an area that does not have a ready supply of process water. Also, the offsite recycling facility used to dispose of spent process pickle liquor was soon to become unavailable. As a result of these concerns, the company constructed an onsite recycling facility designed to recover ferrous chloride for resale and to reuse water and hydrogen chloride for use in steel processing operations. Environmental benefits include the recovery and resale of 20 to 25 t/d of ferrous chloride, 13,440 L/d of hydrogen chloride, and 49,200 L/d of water. In addition, corporate liability was minimized because spent liquor was no longer sent to a disposal facility. 

Both isomers of dimethylhydrazine have been shown to be carcinogenic in rodents following chronic oral exposure and 6-mon inhalation exposure to 1,1-dimethylhydrazine. Increased tumor incidence was observed in mice, although these findings are compromised by the contaminant exposure to dimethylnitrosamine. An increased incidence of lung tumors and hepatocellular carcinomas was also seen in rats but not in similarly exposed hamsters. The U.S. Environmental Protection Agency (U.S. EPA) inhalation slope factors are currently unavailable for dimethylhydrazine. 

According to the vendor, plasma systems are less expensive than retrofitting existing incinerators or building new facilities that have to meet current regulatory standards (D22574L, p. 11). PAR-CON 125 units cost approximately 500,000. The cost per unit treated is currently unavailable (personal communication, Colin Andrews, Plasma Environmental Technologies, Inc., July 1997). 

The major problem in PAH analysis is separation and conclusive identification of individual isomeric compounds, since the biological properties of many PAHs are isomer-specific. Another problem is the unavailability of many reference standards, making optimization of GC-operating parameters and column preparation methods for isomer separation difficult. The best possible separation efficiency is crucial for identification and quantitation of PAHs in any environmental sample. In addition, PAHs must be separated from other classes of compounds mostly encountered in environmental samples. 

Sexual function and fertility reflect a wide variety of functions that are necessary for reproduction and may be affected by exposure to environmental factors. Any disturbance in the integrity of the reproductive system may affect these functions. Patterns of reported infertility vary around the world, but approximately 10% of all couples experience infertility at some time during their reproductive years. Human studies on altered sexual function/fertility provide the most direct means of assessing risk, but data are often unavailable. For many environmental chemicals, it is still necessary to rely on information derived from experimental animal models and laboratory studies. 

The time it takes to rim a simulation is orders of magnitude less than the time it takes to build the equivalent circuit on a breadboard. A simulation can be run through any number of environmental conditions with ease-conditions often unavailable or impractical to duplicate in a laboratory environment. Circuit stimulus and tolerances and their effect on the operation of the circuit can be easily evaluated. 

Toxic metals are a special class of environmental pollutants. Metals cannot be degraded, but only changed from one form (oxidation state) to another. Thus, bioremediation processes for metal-contaminated environments aim at sequestering the metals to make them unavailable to biological components of the ecosystem, or mobilizing them in a manner that allows their flushing from the system for... 

Potential pollutant since amount used industrially is large compared with normal biological levels normally relatively unavailable because of low solubility. Cr(Vt) used in comfort cooling towers, environmental hazard. 

Mercury(I) is assumed to be of minor importance as an environmental contaminant due to the instability of Hg complexes with common atmospheric ligands (e.g. OH and S03 , etc.). However, reliable trace analytical techniques for Hg in the gaseous or aqueous phase are unavailable. 

A9.7.1.6 Speciation of the soluble form can be affected by pH, water hardness and other variables, and may yield particular forms of the metal ion which are more or less toxic. In addition, metal ions could be made non-available from the water column by a number of processes (e.g. mineralization and partitioning). Sometimes these processes can be sufficiently rapid to be analogous to degradation in assessing chronic classification. However, partitioning of the metal ion from the water column to other environmental media does not necessarily mean that it is no longer bioavailable, nor does it mean that the metal has been made permanently unavailable. 

The objectives of the initiator can be divided into two categories business economics and environmental aspects. Co-combustion should not result in an increased unavailability or a reduction of the quality aspects of the by-products, such as fly ash, that could reduce the value or even the utilisation possibilities of the byproducts and lead to lower electricity production costs. 

Valuable assistance in finding information can be obtained by consulting information intermediaries with subject expertise who can identify and access information resources unknown or unavailable locally. These individuals may be in local information centers or may be brokers who specialize in individual information services or creation of compilations of data for a fee. An example of this type of service is the Comprehensive Health and Environmental Monographs (CHEMS) division of Health and Environment International. This service creates detailed reports on the health and environmental effects of a chemical. Professional organizations, database producers, and government agencies can also be sources of experts as well as providers of direct information. An example of the former type of service is UNEP-Infoterra, an international referral and research organization of the... 

A time-weighted average (TWA) or other occupational exposure limit is unavailable for D-limonene. The Workplace Environmental Exposure Level (WEEL) for limonene (terpenes) is 30 ppm as an 8 h TWA. 

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