Hazards environmental, measuring

Measurement of exposure can be made by determining levels of toxic chemicals in human serum or tissue if the chemicals of concern persist in tissue or if the exposure is recent. For most situations, neither of these conditions is met. As a result, most assessments of exposure depend primarily on chemical measurements in environmental media coupled with semi-quantitative assessments of environmental pathways. However, when measurements in human tissue are possible, valuable exposure information can be obtained, subject to the same limitations cited above for environmental measurement methodology. Interpretation of tissue concentration data is dependent on knowledge of the absorption, excretion, metabolism, and tissue specificity characteristics for the chemical under study. The toxic hazard posed by a particular chemical will depend critically upon the concentration achieved at particular target organ sites. This, in turn, depends upon rates of absorption, transport, and metabolic alteration. Metabolic alterations can involve either partial inactivation of toxic material or conversion to chemicals with increased or differing toxic properties. 

In short, the large number of multi-chemical, multi-media environmental measurements associated with hazardous waste investigations during the past few years are unprecedented in scope and complexity. The small community of specialists in the measurements field is being pushed to the limit to reduce the time and cost involved in such measurements and to improve the representativeness of the data that are collected and the accuracy of the data that are reported. 

A second type of control could be provided by national baseline data. Such data indicating the levels of ambient or background contamination usually encountered in different types of demographic settings could help clarify the significance of environmental measurements near a hazardous waste site. 

The two different, but related, eonsiderations in waste disposal are hazard eontrol and loss prevention in the treatment and disposal operations, and the eontrol of environmental hazards. With gas and liquid streams the eontrol of on-site hazards arising from the ehemieal properties and proeessing operations generally follows the prineiples summarized in earlier ehapters. The measures neeessary with solid wastes may, however, differ, partieularly if they are heterogeneous in nature and disposed of on land. 

Cullis, C.R, and Firth, J.G. (ed.) (1988) Detection and Measurement of Hazardous Gases, Hememann, London. Daugherty, J., (1997) Assessment of Chemical Exposures Calculation Methods for Environmental Professionals, Lewis Publishing, London. 

A pesticide manufacturing plant should prepare a hazard assessment and operability study and also prepare and implement an emergency preparedness and response plan that takes into account neighboring land use and the potential consequences of an emergency. Measures to avoid the release of harmful substances should be incorporated in the design, operation, maintenance, and management of the plant. Implementation of cleaner production processes and pollution prevention measures can yield both economic and environmental benefits. 

On the simplest type of instrument (an explosimeter) only one scale is provided, usually with readings from 0 to 100% LEL. However, the detectable changes produced by combustion are too small to be measured accurately in the presence of the low concentrations of contaminants usually encountered in evaluating potential health hazards. For example, the LEL of even the most explosive gas is of the order of 1 %, or 10,000 ppm, which is well in excess of the toxic limit for any gas. Therefore, explosimeters or combustible gas indicators which have only a 0-to-l(X)% LEL explosive scale are not suitable for environmental health testing in the ppm range. More sensitive instruments, including the type used in sampling for environmental health purposes, have a dual scale, in which the second, more... 

Interim measures may be separate from the comprehensive Corrective Action plan but should be consistent with, and integrated with, any longer-term Corrective Action (e.g., corrective measure through an order, an op erating permit, a post-closure permit or interim status closure requirements). To the extent possible, interim measures should not seriously complicate the ultimate physical management of hazardous wastes or constituents, nor should they present or exacerbate a health or environmental threat. Interim measures may add additional costs or work to the comprehensive Corrective Action. Such added costs or work do not preclude implementation of an interim measure. 

In many cases, it is not readily apparent how the potential impacts from different hazards can be translated into some common scale or measure. For example, how do you compare long term environmental damage and health risks from use of CFG refrigerants to the immediate risk of fatality from the fire, explosion, and toxicity hazards associated with many alternative refrigerants This question does not have a right answer. It is not really a scientific question, but instead it is a question of values. Individuals, companies, and society must determine how to value different kinds of risks relative to each other, and base decisions on this evaluation. 

Environmental Condition for Process Measurement and Control Systems Temperature and Humidity Electrical Instruments in Hazardous Locations, Ernest C. Magison, 1978... 

When spills and releases of hazardous gases or liquids occur, the concentration of the hazardous material in the vicinity of the release is often the greatest concern, since potential health effects on those nearby will be determined by the concentration of the substance at the time of the acute exposure. There are many models of routine continuous discharges (e.g., discharges arising from leaky valves in chemical plants), but these carmot be applied to single episodic events. Research on the ambient behavior of short-term environmental releases and the development of models for concentration profiles in episodic releases are cmcial if we are to plan appropriate safety and abatement measures. 

Reportable Quantity (RQ)—The quantity of a hazardous substance that is considered reportable under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Reportable quantities are (1) 1 pound or greater or (2) for selected substances, an amount established by regulation either under CERCLA or under Section 311 of the Clean Water Act. Quantities are measured over a 24-hour period. 

EPA. 1987f Measurement of hydrolysis rate constants for evaluation of hazardous waste land disposal. Volume 1. Data on 32 chemicals. Environmental Research Laboratory. Office of Research and Development. U.S. Environmental Protection Agency, Athens, GA. PB87-104349. 

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. 

The worst hazard scenarios (excessive temperature and pressure rise accompanied by emission of toxic substances) must be worked out based upon calorimetric measurements (e.g. means to reduce hazards by using the inherent safety concept or Differential Scanning Calorimetry, DSC) and protection measures must be considered. If handling hazardous materials is considered too risky, procedures for generation of the hazardous reactants in situ in the reactor might be developed. Micro-reactor technology could also be an option. Completeness of the data on flammability, explosivity, (auto)ignition, static electricity, safe levels of exposure, environmental protection, transportation, etc. must be checked. Incompatibility of materials to be treated in a plant must be determined. 

---