Lead assessors

It should be recognized that there is no requirement for auditors to be trained as Lead Assessors or Registered Internal Quality Auditors. Staff need only to be trained sufficient to carry out the task given to them. 

Forward-thinking companies will put quality first and build a quality assessment team based on cross-functional knowledge and experience. A lead assessor or auditor should be responsible for coordination of the audit and ultimately responsible for the issuance of the report. Composition of the audit team should depend upon the scope of the audit and utilize personnel with pertinent knowledge. The lead assessor or auditor is responsible for resolving any differences of opinion and presenting a unified executive summary of the audit. 

A lead assessor (and/or assessment manager) w ill perform the assessment supported by independent technical assessors with the expertise to look at the specific areas of the laboratory s work that are being accredited. 

Risk assessors tend to build in additional uncertainty factors to avoid healthrelevant underestimates. This is partly done by using screening methods designed to look for worst case situations. Such worse case assumptions lead to intake estimates that exceed reality. For chemicals that present potential risks, more information is needed to allow more refined screening or even the most accurate estima-... 

To deal with this problem the EPA invested in the development and validation of a pharmacokinetic model that is capable of relating intake of lead to blood level. The model also allows the risk assessor to develop blood level estimates that integrate all sources of exposure. Using this model, it becomes possible to determine whether a specific source, such as our suspect water supply, is leading to exposures in excess of the target for all sources combined (this assumes that other sources do not contain levels of lead greater than normal, background... 

Any questions asked by regulatory assessors should be answered as thoroughly and explicitly as possible. It is not productive to be grudging in either the tone or the nature of the response as this will only slow down the assessment process and can lead to additional questions being asked. 

For the sensory evaluation, experienced assessors were used. Prior to sensory evaluation the purity of all flavor components was carefully checked because undesirable trace impurities may severely affect the odor quality of a component and can lead to erroneous conclusions. Different concentrations of each flavor substance in aqueous solution were used (based on their detection thresholds). Furthermore, sensory evaluation was also performed by sniffing the GC-eluate. 

Assessors should base their selection of methods on clearly defined decision criteria, and they need to communicate the results using clear and transparent language. This includes statements on the extrapolation issues that were considered but not addressed, and the magnitude and direction of the bias that may have been introduced by the extrapolation or lack thereof. In lower tiers and prospective risk assessment, this should lead to setting more appropriate UFs and ensure that lower tier approaches are more conservative than higher tier approaches. All this helps assessors to make informed decisions, on one hand, but it also allows the identification of future research needs, on the other hand, especially when methods are not available. 

The risk assessor should be sensitive to certain dose-response patterns that are often encountered in studies on developmental toxicity. For example, the lowest effective doses in adults and young are often similar or may be the same, but the type of effects may be very different as well, the effects on the developing child may be permanent (or lead to latent effects), whereas the effects on the adult may be transient. Also, the end-points used in evaluating alterations in children s health may vary considerably. The difference between the maternal toxic dose and the developmental toxic dose may at times be related to the relative thoroughness with which end-points are evaluated. Also, the variability and level of severity within a particular end-point need to be defined, since end-point variability and level of severity can have a significant effect on the power of the study and the ability to establish an effect level. Approaches to carrying out dose-response assessments are described below. 

The subjectivity of the qualitative assessment (see section 5.1.2.2) also opens the possibility of conscious or unconscious bias by the assessor. For this reason, it is desirable to report the steps from (1) to (5) in a transparent way so that others can review and evaluate the judgements that have been made. This has the advantage that it is always possible to do and that it is sufficient if the result is clearly conservative (protective) overall. However, it has disadvantages with regard to subjectivity when the outcome is not clearly conservative and when using separate uncertainty factors for many parameters that can lead to compounding conservatism. If an exposure/risk assessment contains a number of conservative assumptions, then the above table is likely to end up with an overall assessment that the true risk is probably lower than the quantitative estimate. However, if the assessment attempts to use realistic estimates/distributions for most inputs, then a table of unquantified uncertainties is the likely result. This undoubtedly is a difficulty for decision-makers unless the assessor can evaluate the combined uncertainty relative to the decision-makers decision threshold. 

An uncertainty analysis gives the assessor the opportunity to re-evaluate the scenario, model approaches and parameters of the analysis and to consider their influence in the overall analysis. The practical impact of uncertainty analysis is illustrated within the annexed case-studies, which also clarify how uncertainty analyses follow a systematic methodology, based on a tiered approach, and consider all possible sources of uncertainty. The first step in uncertainty analysis consists of a screening, followed by a qualitative analysis and two levels of quantitative analysis, using deterministic and probabilistic data. The assessor should be aware that an uncertainty analysis cannot answer all the questions, which, moreover, may lead to new questions. 

The set of questions leads to a logical approach for all potential mixture assessment situations. For example, mixtures of which the composition is unknown or partially known and which have an unknown frequency of occurrence and unknown or unique concentration ratios should be assessed on a case-by-case basis using toxicity tests with whole mixture samples in the field or the laboratory. If this is not feasible, the risk assessor can opt to gather additional data about the mixture composition or its occurrence and subsequently reassess the mixture. It also leads to a logical approach for mixtures of which the composition is known, namely, the application of component-based methods or the use of appropriate data from similar cases. 

The third step in the risk assessment process is exposure assessment. In exposure assessment, the intake of a toxic agent from the environment is quantified using any combination of oral, inhalation, and dermal routes of exposure. This assessment may include a component for each route, such as when an assessor would investigate the potential impact of a point source of pollution. In this case, the magnitude of exposure depends on the amount of chemical used or released, chemical fate and transport, chemical concentration at the point of exposure, the routes and rates of uptake, the duration, the exposure setting (location and number of potential receptors, land use and human activities that could lead to exposure), and characteristics of receptors potentially exposed to the chemical. 

MRL has never been intended as a one-size-fits-all tool for all hazardous waste site exposure scenarios rather, it is merely a starting point for further examination of potential health risk. Therefore, at sites where methylmercury is present in combination with other known or suspected neurodevelopmental toxicants, such as lead or polychlorinated biphenyls (PCBs), and in which exposure is primarily episodic in nature, the health assessor might consider using a value below the chronic oral MRL for methylmercury as a starting point for determination of further site investigation. (A more complete description of the uses of MRLs and other HGVs can be found in Chou et al. 1998 and Risher and De Rosa 1997.)... 

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