RISK ASSESSMENT
When using any new procedure or modifying an existing protocol it is essential to carry
out a risk assessment of all aspects of the work process, namely starting materials, culture
procedures, product purification and waste disposal. For most chemicals and reagents used
in cell culture there are standard texts and sources of information, most obviously the
manufacturer, which enable rapid assessment of risk based on the properties of the reagent,
its physical form, the quantities used and the procedures to which it is to be subjected.
However, there are a number of factors unique to the manipulation and culture of animal
cells which make risk assessment a more difficult and sometimes uncertain process. The
following paragraphs aim to identify the safety concerns specifically relating to cell culture
and to give some general guidance for risk assessment in these areas.
(1) Undefined Components of Growth Media.
Numerous growth medium supplements, notably foetal bovine serum, can provide a
potential source of virus contamination (Erickson et al. 1991). In general such supplements
cannot be readily sterilised since this often results in their inactivation or degradation.
Thus, it is important to obtain such materials from suppliers which guarantee that they
stock only from uninfected sources or accredited virus free animal herds. Some
manufacturers may carry out tests for the detection of adventitious agents, but this is
limited to specific organisms (eg. mycoplasma and Bovine Viral Diarrhoea Virus).
Obviously, if human (and primate) sources of undefined reagents are avoided then the risk
of infection in laboratory workers by this route is minimised. There are a number of serum
free defined culture media and sources of recombinant growth factors which eliminate the
possibility of virus transmission via culture media components. Unfortunately, these are
not yet widely used and they can be very expensive. However, the search for a cheaper
culture medium may lead to the use of less pure reagents subjected to lower standards of
quality assurance. Thus, in the long term, the use of less expensive culture media may be
counterproductive both in terms of safety and quality.
2) Cells and Adventitious Agents
Risk assessment of animal cell cultures is a potentially confusing area since the cells are
essentially undefinable and prone to variation. However, the primary cause for concern, in
relation to laboratory work with cells, is the potential of cell cultures to sustain virus or
other organisms which might infect laboratory workers. Thus practical approaches to risk
assessment of animal cell cultures have been based on the virological risk represented by
the species and tissue of origin (Frommer et al., 1993). Human and primate cells derived
from blood and lymphoid tissue are of greatest concern as carriers of serious human
pathogens. Whilst non-human, non-primate sources of cells in general represent a much
lower risk to laboratory workers some rodent viruses can cause human infection (eg. Hay,