* RECOMBINANT DNA MOLECULES ARE DEFINED AS MOLECULES CONSISTING 
OF SEGMENTS OF NATURAL OR SYNTHETIC DNA WHICH HAVE BEEN 
COMBINED OUTSIDE LIVING CELLS BUT HAVE THE CAPACITY TO INFECT 
AND TO BE PROPAGATED IN SOME HOST CELL* NOVEL RECOMBINANT DNA 
MOLECULES ARE THOaE THAT DIFFER FROM DNA MOLECULES ARISING 
AT A BIOLOGICALLY SIGNIFICANT LEVEL BY NATURAL PROCESSES.' 
SEVERAL NATIONAL GUIDELINES FOR RECOMBINANT DNA RESEARCH STATE 
THAT CONTAINMENT MEASURES MAY BE RALAXED ONCE A CLONED DNA 
FRAGMENT HAS BEEN BIOCHEMICALLY CHARACTERIZED AND SHOWN TO BE 
’FREE OF HARMFUL GENES ' (NIH GUIDELINES) OR 'DEVOID OF ANY KNOWN 
PATHOGENIC CHARACTERISTIC’ (FRENCH GUIDELINES). THE EMBO COMMITTEE 
BELIEVES THE LATTER TO BE A MORE FEASIBLE REQUIREMENT BUT NEITHER 
CAN READILY BE MET AND THE COMMITTEE FINDS IT DIFFICULT TO SUGGEST 
WHAT SORTS OF EXPERIMENTAL TESTS MIGHT BE DEVISED TO MEET THESE 
REQUIREMENTS. AN ALTERNATIVE MIGHT BE TO REQUIRE THAT NATIONAL 
COMMITTEE^ DECIDE UPON REQUEST^ TO RELAX THE CONTAINMENT 
PRECAUTIONS FOR CLONED DNA ON A CASE BY CASE BASIS. 
REGARDS JOHN TOOZE, EMBO* HEIDELBERG 
[Appendix A — 97] 
