Specificity, assessing

Biological sui veys shall be fuUy integrated with toxicity and chemical-specific assessment methods in state water-quahty programs. ... 

This sample, referred to in Chapter 2, can serve as a guide for planning and conducting assessments of tollers. It may require additions, revisions, or other modifications in order to meet the needs of facility specific assessment objectives, the facility setting, or other special circumstances. This sample includes ... 

In all of the workshops, but especially in the FAT and Exposure Assessment workshops, the need for better understanding and model representation of soil systems, including both unsaturated and saturated zones, was evident. This included the entire range of processes shown in Table II, i.e., transport, chemical and biological transformations, and intermedia transfers by sorption/desorption and volatilization. In fact, the Exposure Assessment workshop (Level II) listed biological degradation processes as a major research priority for both soil and water systems, since current understanding in both systems must be improved for site-specific assessments. 

Though extensive research has been recently reported in the open literature concerning biodegradation of azo-dyes, there is still a need for additional research. The close link between dye structure and reaction pathways and rates makes it difficult to extrapolate results obtained with one dye to that with others, even belonging to the same class. Dye-specific assessment of process rates and yields is therefore required. Also, the degradation potential of several bacteria or consortia active toward xenobiotics in dye degradation is far from being fully assessed. 

To assess improvement, the physician should conduct specific assessments at baseline and after a trial period of 1 to 3 weeks. 

A comprehensive approach to a states response to a chemical terrorism includes having a plan not only for the crisis and consequence management phases of the incident, but also for all elements required for complete resolution of the event. This may include the necessity to definitively establish whether chemical agents were used, to provide supporting evidence to confirm other analyses, or to provide the forensic proof required to support a criminal prosecution. The collection and analysis of biomedical samples - blood, urine or other tissue from affected humans or animals - is one of the means for providing such information. Although current capabilities such as urinary thiodyglycol excretion or plasma cholinesterase activity can be performed, there is scope for far more sensitive and specific assessments that overcome the limitations of these approaches. 

The uncertainty analysis that is a part of formal EcoRA methodology is designed to ensure adequate estimation of ecological effects based on a state-of-the-art scientific basis. Moreover, if applied on a local scale for site-specific assessments, with the use of empirical input data as biogeochemical parameters, the CLL approach is likely to provide results with a higher degree of confidence than the formal EcoRA model. 

A recently pubhshed WHO/IPCS document regarding chemical-specific adjustment factors for interspecies differences and human variability (WHO/IPCS 2005) provides guidance for use of toxicokinetic data in dose-response assessment to develop the so-called Compound-Specific Assessment Factors (CSAFs) (Section 5.2.1.12). 

Concern has been raised that infants and children are at higher risk than adults from exposure to environmental chemicals. The question of an extra assessment factor in the hazard and risk assessment for chemicals of concern for children has therefore been raised and the rationale for such a children-specific assessment factor has been discussed. 

In conclusion, the traditional assessment factors (interspecies, intraspecies, subchronic-to-chronic, LOAEL-to-NOAEL, and database-deficiency) are considered to cover the concerns and uncertainties for children adequately, i.e., no children-specific assessment factor is needed when setting tolerable intakes. However, it is recommended to perform children-specific risk assessments for chemical substances in products and foods intended for children, based on specific exposure assessments for children. 

The probabilistic approach allows for a closer link with specific knowledge or lack of knowledge in specific assessments. For example, one may be more confident in the magnimde of the possible interspecies difference in one case than another. This may be expressed in the width of the relevant distribution for the assessment factor. However, in many cases, even the range of uncertainty is uncertain, and for those situations default distributions are called for. 

Rutgers, M. (2000). Site-specific ecological risks a basic approach to the function-specific assessment of soil pollution, ISBN 9073270448, Wageningen, The Netherlands. 

Although epidemiological studies of some of the industries where exposure to chemicals considered in this volume occurs have been conducted, exposure to many of these chemicals has rarely been specifically assessed for epidemiological purposes. Quantitative estimates of historical exposure are often not available and therefore it is difficult to identify highly exposed subgroups or to estimate individual exposures. Without such data, it is difficult to evaluate exposure-response relationships which might, in some cases, allow cancer excesses to be attributed to specific agents when there is mixed exposure. 

One mortality study of workers at a 4,4 -bipyridyl manufacturing plant using pyridine as a starting material showed a small non-significant excess of lung cancer mortality. This excess could not be attributed to specific chemical exposures within the plant, and it was not clear if the risk associated with pyridine exposure was specifically assessed. 

Al fundamental question about the interpretation of acidic aerosol data is whether researchers can characterize past and current atmospheric concentrations and distributions (spatial and temporal) with sufficient accuracy for studies of their effects on ecosystems and human health. Part of the answer to this question can be provided by a review of the methods that have been used to measure the strong acid content of aerosol particles collected from the atmosphere. This chapter serves as such a review, and, in evaluating analytical procedures, it specifically assesses the ability of each procedure to overcome sampling artifacts, to distinguish between strong and weak acids, to properly partition strong acidity between gas-phase and aero-sol-phase species, and to quantitate strong acidity at the levels at which it is found in the ambient atmosphere. 

NCRP emphasizes, however, that waste classification does not provide a substitute for establishing requirements on treatment and disposal of specific wastes at specific sites, requirements on remediation of contaminated sites, or decisions by regulatory authorities about the acceptability of any such activities. The acceptability of particular waste management or disposal activities must be based on site-specific assessments of risks posed by well characterized wastes. Waste classification, although useful, can only inform the process of... 

Second, generic and site-specific assessments of near-surface disposal facilities for radioactive waste have shown that allowable doses to hypothetical inadvertent intruders usually are more restrictive in determining acceptable disposals than allowable doses to individuals beyond the boundary of the disposal site. This conclusion is based on predictions that concentrations of radionuclides in the environment (e.g., ground-water) at locations beyond the site boundary usually should be far less than the concentrations at the disposal site to which an inadvertent intruder could be exposed, owing to such factors as the limited solubility of some radionuclides, the partitioning of radionuclides between liquid and solid phases, and the dilution in transport of radionuclides in water or air beyond the site boundary. More people are likely to be exposed beyond the site boundary than on the disposal site, but acceptable disposals of radioactive waste in near-surface facilities have been based on assessments of dose to individuals, rather than populations. 

Measurement endpoint Numerical expression of a specific assessment endpoint or effect criterion (e.g., IC50, NOEC, LOEC). Volume 1(3,10),... 

What is the objective of the assessment a specific assessment for a contaminated site, or a generic assessment that will derive a conservative... 

There are various mathematical models that can be used to describe and analyze experimental data (Scholze et al. 2001). In addition to these curve-fitting approaches, response surface models are also available (e.g., Greco et al. 1995), but these are suitable primarily for the analyses of experimental data, rather than for predictive purposes. As an example, Altenburger et al. (2004) applied both concentration addition and response addition and observed that the combined effect of a 3-compound mixture out of 10 identified sediment toxicants was sufficient to explain the observed combined effect of the more complex mixture. For identifying remediation priorities in site-specific assessment of complex contamination, this approach has great potential. 

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