Please note that two errors appear in this paper:

The author's address contains a spelling mistake and should be :
Katholieke Universiteit Leuven Laboratorium voor Longtoxicologie, Herestraat 49, B-3000 Leuven, Belgium.

In Table 2, the entry for Bull NY Acad Med should read:
Bull NY Acad Med                0.370                1

and the second entry for Br J Urol should be deleted.