106 
Excerpted from "Recombinant DNA: Fact and Fiction," Cohen, Stanley 
N. , Science Vol. 195, pp. 654-657, 18 February 1977. Copyright© 
1977 by the American Association for the Advancement of Science. 
Much has been made of the fact that, 
even if a particular recombinant DNA 
molecule shows no evidence of being 
hazardous at the present time, we are 
unable to say for certain that it will not 
devastate our planet some years hence. 
Of course this view is correct; similarly, 
we are unable to say for certain that the 
vaccines we are administering to millions 
of children do not contain agents that 
will produce contagious cancer some 
years hence, we are unable to say for 
certain that a virulent virus will not be 
brought to the United States next winter 
by a traveler from abroad, causing a 
nationwide fatal epidemic of a hitherto 
unknown disease — and we are unable to 
say for certain that novel hybrid plants 
being bred around the world will not 
suddenly become weeds that will over- 
come our major food crops and cause 
worldwide famine. 
The statement that potential hazards 
could result from certain experiments 
involving recombinant DNA techniques 
is akin to the statement that a vaccine 
injected today into millions of people 
could lead to infectious cancer in 20 
years, a pandemic caused by a traveler- 
borne virus could devastate the United 
States, or a new plant species could un- 
controllably destroy the world’s food 
supply. We have no reason to expect 
that any of these things will happen, but 
we are unable to say for certain that they 
will not happen. Similarly, we are unable 
to guarantee that any of man’s efforts to 
influence the earth’s weather, explore 
space, modify crops, or cure disease will 
not carry with them the seeds for the 
ultimate destruction of civilization. Can 
we in fact point to one major area of 
human activity where one can say for 
certain that there is zero risk? Poten- 
tially, we could respond to such risks by 
taking measures such as prohibiting for- 
eign travel to reduce the hazard of dead- 
ly virus importation and stopping experi- 
mentation with hybrid plants. It is pos- 
sible to develop plausible "scare sce- 
narios" involving virtually any activity 
or process, and these would have as 
much (or as little) basis in fact as most of 
the scenarios involving recombinant 
DNA. But we must distinguish fear of 
the unknown from fear that has some 
basis in fact; this appears to be the crux 
of the controversy surrounding recombi- 
nant DNA. 
Unfortunately, the public has been led 
to believe that the biohazards described 
in various scenarios are likely or prob- 
able outcomes of recombinant DNA re- 
search. “If the scientists themselves are 
concerned enough to raise the issue," 
goes the fiction, "the problem is prob- 
ably much worse than anyone will ad- 
mit." However, the simple fact is that 
there is no evidence that a bacterium 
carrying any recombinant DNA mole- 
cule poses a hazard beyond the hazard 
that can be anticipated from the known 
properties of the components of the re- 
combinant. And experiments involving 
genes that produce toxic substances or 
pose other known hazards are prohibit- 
ed. 
