Hazardous contaminants

Biosensors ai e widely used to the detection of hazardous contaminants in foodstuffs, soil and fresh waters. Due to high sensitivity, simple design, low cost and real-time measurement mode biosensors ai e considered as an alternative to conventional analytical techniques, e.g. GC or HPLC. Although the sensitivity and selectivity of contaminant detection is mainly determined by a biological component, i.e. enzyme or antibodies, the biosensor performance can be efficiently controlled by the optimization of its assembly and working conditions. In this report, the prospects to the improvement of pesticide detection with cholinesterase sensors based on modified screen-printed electrodes are summarized. The following opportunities for the controlled improvement of analytical characteristics of anticholinesterase pesticides ai e discussed ... 

Site H was the only site at which the contractor had implemented comprehensive and effective site control elements. The Site H contractor had established site work zones, a buddy system, and site communication procedures consistent with 1910.120(d). This contractor had also established exclusion zones and contamination reduction zones to control migration of site contaminants to clean areas of the site when work within these areas introduced the potential for exposure to hazardous contaminants. The audit team supported this contractor s use of flexible and temporary work zone boundaries based on monitoring results and hazard determinations. 

EMGRESP is a source-term and dispersion emergency response screening tool for calculating downwind contours with a minimum of user input and computational expense in the event of a release of a hazardous chemical. The program provides hazardous contaminant information, calculates toxic concentrations at various distances downwind of a release, and c" the... 

All supply inlets without a specific exhaust have the same problem, the spreading of contaminants in the room outside the supply air zone. When the inlets are used to create a cleaner zone in a normal workroom this is usually no problem. When a supply inlet is used to blow away some hazardous contaminant it is necessary to combine it with a specific exhaust, or the rest of the room will be contaminated. 

Ihe implementation of the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (Superfund) has underscored a number of the weaknesses in our capabilities to measure the chemical characteristics of wastes. We are now being called upon to identify and quantify with unprecedented sensitivity hundreds of chemicals found in many types of materials within waste sites, near discharges of hazardous contaminants, and in the surrounding environments. Extrapolations from a limited number of measurements must indicate the general environmental conditions near waste sites. The measurements have to be made faster and cheaper than ever before, with the precision and bias of each measurement fully documented. Thus, the technical challenges facing the monitoring community are substantial. 

Chemical oxidation typically involves reduction/oxidation (redox) reactions that chemically convert hazardous contaminants to nonhazardous or less toxic compounds that are more stable, less mobile, or inert. Redox reactions involve the transfer of electrons from one compound to another. Specifically, one reactant is oxidized (loses electrons) and one is reduced (gains electrons). The oxidizing agents... 

When changing the supplier of reactants, the specifications have to be evaluated carefully for the presence of different chemical components as impurities to identify potentially hazardous contaminants. 

Because airborne and volatile contaminants can present a significant threat to industrial workers health and safety, identification and quantification of these airbome and volatile contaminants through air/soil monitoring is an essential component of a health and safety program at an industrial site having hazardous substances. The purpose of air and soil monitoring is to identify and quantify airbome and volatile hazardous contaminants in order to determine the level of plant worker s protection needed. 

Dust The dust in your home may contain many hazardous contaminants, e.g., lead or pesticides. Many of these can be brought into the home on shoes or by pets. Removing shoes can reduce contamination in the home. 

The Advanced Recovery Systems, Inc. (ARS) developed the patented, ex situ DeCaF hydrometallurgical technology to decontaminate fluoride by-products and to recover recyclable metals. The technology uses a proprietary acid mixture to digest the fluoride matrix, freeing radioactive contaminants (e.g., uranium, thorium, or radium) and hazardous contaminants (e.g., lead, arsenic, or chromium). Radioactive elements are recycled or disposed. Metals are also recycled, and fluoride is recovered as a high-value salt for aluminum smelting. 

Bio-Electrics, Incorporated, has developed the Electrofrac Detoxification System to treat hazardous contaminants in soil. The system, which was developed from gasification research, uses electrodes placed in soil to heat the site. There are potential applications of this technology for removal of volatile organic compounds (VOCs), pyrolysis of non-VOCs, treatment of organic residues, and in situ vitrification of soils and asbestos. There have been bench-scale tests of the technology for remediation applications. 

Analyzing Food for Nutrition Labeling and Hazardous Contaminants, edited by Ike J. Jeon and William G. Ikins... 

DOE — Organics, PCBs, petroleum/fuel hydrocarbons, solvents, TCE, unspecified VOCs, and unspecified SVOCs are among the contaminants found. Metals cited most often include lead, beryllium, mercury, arsenic, and chromium. Radioactive contaminants are present at most installations the most frequently cited are uranium, tritium, thorium, and plutonium. In addition, mixed waste containing both radioactive and hazardous contaminants is of particular concern to the DOE because of the lack of an acceptable treatment technology. 

Nowadays the nature of solid waste has evolved. Every home contains hazardous products, or products that can harm human health or the environment if improperly handled. They are potential sources of hazardous contaminants in municipal solid waste (MSW). As an example, Americans generate 1.6 million tons of household hazardous waste (HHW) per year (http //www.epa. gov/enaoswer/non-... 

WASTOXHAS is designed to assess all solid wastes likely to contain potentially hazardous contaminants, such as landfilled, re-used and solidified/stabilized wastes. Besides solid wastes per se, this approach can also be applied to a wide range of other solid media including ... 

Semard, G., A. Bruchet, P. Cardinael, et al. 2008. Use of comprehensive two-dimensional gas chromatography for the broad screening of hazardous contaminants in urban wastewaters. Water Sci. Technol. 57 1983-1989. 

The source is defined by the amount and nature of a potentially hazardous contaminant. The degree to which a source poses a risk depends on the presence of a means of transport (the pathway) for the contaminants to the receptor (the plants, animals and/or humans and even buildings that may be adversely affected by the contamination). Contaminants can move from the source to the receptor via food, soil, air and water. For humans, the main ways that contaminants can enter our bodies are by ingestion, inhalation and direct contact, for example, by absorption through the skin. 

Bioremediation enhances natural transformation by optimizing the conditions necessary for the process. The process is carried out by organisms capable of degrading the compounds. Both anaerobic and aerobic conditions may be involved in enhancing transformation. Commonly, four possible approaches for bioremediation of hazardous contaminants are employed ... 

The modification of mineral structure by substitutions is, in fact, the strength of practical CBPCs. With substitution, one can trap radioactive and hazardous contaminants in... 

This test is the key to success of any stabilization method for treatment of hazardous waste. Because the waste is crushed and leached using acidic water, the actual leaching of the contaminants depends on their solubility. Thus, as in the case of CBPC formation discussed in Chapters 4-6, solution chemistry plays a major role in stabilization. For this reason, we review the solution chemistry of the hazardous contaminants before we proceed to the actual stabilization. 

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