Trial Report – Closed Transfer Systems (CTS)
The measuring method used to measure operator exposure during the filling process has been significantly improved by several innovative measures, such as a better washing program with less water, the operation of the washing machine with demineralized water, the use of stainless steel sieves for sample preparation and new overalls. In particular, during the test period, valuable experience was gained with the correct textile composition, the correct storage of the contaminated dosimeters and the evaluation of the measured data. The complex process could be made more efficient by new ideas in many places, so that a faster processing of the trials is possible. The measurement accuracy was improved or at least maintained depending on the dosimeter. Due to the independent filling of the tracer solution in PPP canisters, short storage times between filling and the beginning of the test could be realized, whereby the stability of the tracer and thus also the measuring accuracy are positively influenced. Especially in the variants without the CTS, the results show in some cases larger situation-dependent differences in the exposure of different operators. The execution of the tests should therefore be carried out by several operators with a sufficient number of repetitions. It can be deduced from the trial results that visors, laboratory gloves and underwear can largely be dispensed with when evaluating a CTS, since the proportion of these dosimeters in the total exposure is negligible. For overalls, the particular problem is that only a few valid measurements above the detection limit are available, although appreciable exposures may occur. On the other hand, the distribution of measurement results in protective gloves allows the derivation of a suitable standard reference value and is well suited as a basis for evaluating the filling systems. Due to the limits of quantification of the dosimeters, however, restrictions in the measuring methodology are set, which must not be disregarded when defining the test requirements.