Over the last 30 years, recombinant DNA (rDNA) technology has evolved from an exciting new "ground-breaking" set of techniques
into an established science. Industry and public concerns regarding the safety of rDNA technology developed in parallel with
the emergence of the science. In the beginning of the rDNA era, the possibility of recombinant organisms becoming pathogenic
or otherwise causing harm to humans or the environment was an unfamiliar and previously unassessed risk. Now, prokaryotic
and eukaryotic expression systems engineered using rDNA methods are routinely used for the production of a wide range of products
for medical, diagnostic, and other uses. The use of biological and physical containment methods, resulting from risk assessment
experiments, and a history of safe use of recombinant organisms to date, have alleviated initial concerns regarding the safety
of this technology.
In this paper, we review the evolution of biosafety practices and detail current industry regulations and approaches for treatment
of waste from production operations using rDNA-derived expression systems. The primary focus centers on a possible hazard
associated with rDNA technology that has not been extensively considered to date — the potential for chromosomal DNA from
recombinant organisms to cause harm to humans or the environment via horizontal gene transfer to bacteria. As we prepared
to start-up our new biopharmaceuticals manufacturing plant in Ireland in 2004, a key question for us was "Does the DNA from
inactivated CHO cells that we routinely deliver to our site waste hold tanks, and subsequently to the municipal waste treatment
facility, pose any threat to the environment?" The scientific information and thought processes we engaged in assessing this
risk are described here.
THIRTY YEARS OF RISK ASSESSMENTS FOR rDNA TECHNOLOGY
In 1979, Dr. Rollin Hotchkiss wrote to the US NIH Recombinant DNA Advisory Committee: "I did in 1950, after some deliberation,
perform the first drug resistance DNA transformations, and in 1964 and 1965 took part in early warning against indiscriminant
'transformations' that were then being imagined." The extent of scientists' apprehensions regarding this new field of rDNA
technology increased and at the June 1973 Gordon Research Conference on nucleic acids in New Hampton, NH, the US NIH was asked
to study the issues of safety for laboratory workers. Concern was so great that a number of notable scientists called for
a moratorium on rDNA research. These events led directly to the 1975 Asilomar Conference and the creation of NIH oversight
of rDNA research in the US. Shortly afterwards, Canada, the United Kingdom, and other countries instituted similar regulations
and oversight bodies. The initial regulations were fairly restrictive, requiring moderate to high physical and biological
containment. Risk assessment experiments were initiated to quantify risks based on data rather than supposition.
