Subject conservatism

Initial discussions on the correctness and/or conservatism of the added areas method led to many organizations undertaking further research on the subject. 

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. 

It would be well, now, to discuss one or two of the major problems that face the research worker when he first confronts the literature of the essential oils. Apart from the language difficulty, the chief problem is undoubtedly that of nomenclature, a problem faced, of course, by every researcher in every field. But in the case of the essential oils, the difficulty seems somehow aggravated. A long history, a world-wide traffic, and the customary conservatism have all contributed to the invention and retention of an inappropriate and ambiguous terminology, both botanical and chemical. This condition is of direct concern to every one who works in the field. It influences the acceptability of a good deal of the literature on the subject. 

In practice, and depending on the degree of conservatism incorporated during review of individual hazardous compounds subjected to the AEGL process, the AEGL concentration established for any given effect level can be less than the known experimental concentrations at which such toxicological effects have been observed to occur. 

It is the destiny of HRA specialist that the results of his analysis are considered being more subjective than elaboration of other, objective PSA data (hardware failures statistics). As soon as the PSA results indicate high level of operational risk, there may be conclusion that such unfavorable result is not reflection of reality, but it has been caused by too high level o f conservatism of HRA expert. As a consequence, HRA expert may need to justify his results much more in detail than other members of PSA team. 

The construction of the Old Kingdom Pyramids has been the subject of wide-ranging speculation shading off into the mysticism of pyramidology. Two notions worth examining are firstly, that their construction techniques evolved only very gradually in surroundings of almost immutable conservatism, hidebound by tradition and second, that they were carried out at an almost superhuman scale and accuracy. 

Welding. Considerable difficulty has been experienced in the design of welds subject to cyclic pressure stresses. Extreme conservatism with regard to metal thickness is helpful in eliminating fatigue failure of welds. Nozzles welded to pump heads have heavy sections at the weld.. I ull-penetration welds are used throughout, and butt wolds are used if possible. The inside surfaces of welds are machined smooth when they are accessible. 

---