She said trace contamination with other animals - including pig and horse - could take place at abattoirs and processing plants dealing with more than one species "even with thoroughcleaning and good hygiene practice".
Such a thorough house-cleaning might be the only way that Dudley will be able to convince Congress not to ban BP from ever again drilling another well in U.S. waters.
At key points, components will go through further careful cleaning with ethanol and a thorough sterilisation with hydrogen peroxide vapour which, to add to the challenges, has to kept above 15C.