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This research project aims to produce a statistical model which can estimate variability in dietary intake, between-person and within-person, whilst accounting for day-to-day variation.
<p>The model aimed to have flexibility to account for real-life influences on between-person and within-person variation in consumption, and be a sophisticated improvement on current models whilst remaining simple enough to be practicable to those involved in risk assessment.
<p>Data for modelling was taken from the Dietary and Nutritional Survey of British Adults; a study of 2197 adults who each kept a detailed diary of all food and drinks consumed over a seven-day period.
<p>As details on pesticides and mycotoxins were originally unavailable, the average calorific and retinol intake information was applied to the construction of a formal mathematical model that took account of day-to-day variability differing from person to person.
<p>The model was gradually extended to include fixed personal traits such as age and sex, and limited published data on pesticide residues and mycotoxins were eventually introduced.
<p>Having such a complex variance structure, it was necessary to fit the model using the Bayesian technique of Markov chain Monte Carlo modelling.
<p>The accuracy of prediction of numbers of days when particular intake levels were exceeded was used as a measure of the model reliability with this data set.
Previous models for estimating average consumption of chemicals contained in food and the levels of variability of the amount consumed on a person to person, day-to-day basis have incorporated major simplifications and assumptions regarding consumption patterns.
<p>For instance, one person may have a higher day-to-day variability of consumption of a particular product than another person, and differences in the consumption of particular foods between persons may also be influenced by more systematic factors such as age, sex or location of residence.
<p>When there is a risk of chemical contaminants being found in food, e.g. mycotoxins or pesticide residues, it is important to know how frequently and in what amounts a person might be consuming a potentially hazardous food and the concentration of the contaminant within the food.
<p>There is a need for a model that can account for between-person variation, and within-person variation in consumption on a day-to-day basis, that can be applied in risk assessment of food chemicals.
<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food Standards Agency Research webpage</a>.