Dave, Not knocking your use of plastic bags
but I personaly would be a little apprehensive
in using these !!!
Mainly because of the chance of the plastic tearing , therfore possibality of transfer,
you may have been ok up to now
but thier is always that chance.
I personaly use polystyrene blocks that you find for packing delicate items etc,
cant find a great deal of difference between the bought blocks and packing.
Geoff