Quantitative Risk Assessment of Chemicals: The Problem or the Panacea?. David P. Lovell and Gail Thomas, BIBRA International, Woodmansterne Road, Carshalton, Surrey, SM5 4DS, United Kingdom
Quantifying the risks associated with the intake of food chemicals and contaminants by the human population is of both scientific and public concern. Attempts to base the risk assessment process in the USA and some other countries on the results of quantitative risk assessments (QRAS) have both strong proponents and critics.
BIBRA International carried out a critical review of the methodology currently used for QRA for the UK Ministry of Agriculture Food and Fisheries (MAFF). The most widely used of the many mathematical models proposed for extrapolation of data from animal studies to low dose human exposures is the Linearized Multistage Model (LMS) which has effectively become the default approach for many QRAS. It was concluded that methods used in the USA, such as the LMS model, have serious limitations and should not be automatically transferred to the UK or European regulatory environment.
This presentation illustrates some of the present QRA procedures using both simulated and actual toxicological data. Two basically different approaches for progress exist. Firstly, methods which try to simplify the assessment of the toxicological data to provide less precise estimates but which allow relative rankings of the risk associated with chemicals. Secondly, the development of more specialized and more relevant models based upon the toxicokinetics and toxicodynamics properties of the chemicals being assessed. These physiologically-based pharmacokinetic (PB-PK) and biologically-based dose-response models may allow more understanding of the toxicological mechanisms and consequently more accurate estimates of the actual risk associated with human exposure.
(This work forms part of a research project funded by the UK Ministry
of Agriculture, Fisheries and Food. The results of the research
are the property of the Ministry of Agriculture, Fisheries and
Food and are Crown Copyright.)