Worst-case conditions, robustness

For the Industrial setting, the outdoor worker scenario, as mentioned above, represents a worst case. Owing to wind and weather conditions, one assumes that the worker Is exposed to dust only 50% of his approximately 225 workdays. The maximum dust concentration Is the normal nuisance dust TLV (9) of 10 kg/m, breathed by a 70-kg adult at a rate of 12.1 nP" per 8-hour workday (4). A factor of 10 Is Introduced (see equation below) to account for a more robust worker population than the general population. From these assumptions, the calculation Is... 

As an alternative, SST limits can be determined from the results of a robustness as recommended by the ICH. It can be done using the worst-case results for the response, derived from the experimental design results. This allows defining SST limits for responses such as resolution or peak asymmetry. The main idea behind the approach is that the most extreme results are considered, obtained under experimental conditions resulting in acceptable quantitative determinations. SST limits can thus only be meaningfully derived when the tested method is considered robust concerning its quantitative aspect. Then, nowhere in the domain, described by the experimental design, a problematic quantitation occurs, even not at the conditions where the SST responses are worst. 

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