Risk assessment. Principles and consequences*
I. F. H. Purchase
School of Biological Sciences, University of Manchester,
Oxford Road, Manchester, UK
Abstract: Risk assessment is an important tool in deciding how
to allocate resources to controlling risks. In most cases it is based
on hazard data derived from animal experiments and on exposure data
from an assessment of the likely or actual exposure of the population
of interest. Recent advances have improved the understanding of the
use of the no adverse effect level (NOAEL) and safety factor for risk
assessment by providing a scientific justification of the 100-fold safety
factor. Concern about the risks of exposure by various routes simultaneously
(aggregate exposure) and the risks of exposure to mixtures (cumulative
risk assessment) have lead to new approaches to these issues. For many
years, risk assessment of genotoxic carcinogens has relied on low-dose
extrapolation using mathematical models. Recently, these methods are
being reconsidered and, in some cases, replaced with the NOAEL/safety
factor approach combined with all information on the mechanism of action
and the magnitude of the response. It is vitally important to ensure
that risk assessment provides accurate and unbiased estimates of risk
of exposure so that appropriate measures can be taken to control the
risks.
*Lectures presented
at the 4th Congress of Toxicology in Developing Countries (4th CTOX-DC),
Antalya, Turkey, 6-10 November 1999
Back to Contents for access to full
text
