Requirements Gathering Overview

Having defined and gathered data adequate for an initial reserves estimation, the next step is to look at the various options to develop the field. The objective of the feasibility study is to document various technical options, of which at least one should be economically viable. The study will contain the subsurface development options, the process design, equipment sizes, the proposed locations (e.g. offshore platforms), and the crude evacuation and export system. The cases considered will be accompanied by a cost estimate and planning schedule. Such a document gives a complete overview of all the requirements, opportunities, risks and constraints. 

Adequate extrapolation of results from standard laboratory toxicity tests to other time scales of exposure and response requires observations on the time course of toxic effects. These observations can then be used to construct time-to-event models, such as the DEBtox model mentioned above. These models explicitly address both intensity and duration of exposure to hazardous chemicals, and better use is made of the data gathered from toxicity experiments. Diverse endpoints in time can be addressed, and individual organism characteristics and/or environmental circumstances (e.g., temperature) can be incorporated as covariables. An overview of time-to-event models and approaches and their use in the risk assessment of chemicals is provided by Crane et al. (2002). 

The presentation here provides an overview of tlie uses of a perfused skin model such as the IPPSF in percutaneous absorption and dermatotoxieokinetie studies. One of its major advantages is that both absorption and toxicity may be assessed in the same preparation. The pharmaeokinetic models developed arc experimentally verifiable. The major limitations are centered on the cost of the preparation and the technical expertise required to successfully conduct the studies. The overall cost is significantly greater than in vitro diffusion cell studies or in vivo rodent experiments, comparable to human skin equivalent and larger mammal (dog, pig, primate) in vivo work and much less expensive than human trials. However, cost alone is not a sufficient criterion. These studies are humane more information may be gathered than is obtainable with either in vitro or in vivo work. Optimal benefit may be achieved if these studies serve as a bridge between in vitro human/animal and in... 

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