Reference ranges for key biomarkers of chemical exposure within the UK population

Human biomonitoring (HBM) is a widely accepted tool to aid assessment of chemical uptake in risk assessment. However, our understanding of the biological relevance of the results of HBM can be restricted, due in some part to the limited information on background environmental exposures and biomarker concentrations in the general population. The study described here specifically addresses the question of what constitutes normal background levels in the UK population of a number of biomarkers (the chemical itself or one of its stable metabolites) for a variety of environmental chemicals that are frequently encountered because of their widespread use. The environmental chemicals selected for this study were benzene, chlorinated hydrocarbons, dithiocarbamates, cadmium, mercury, naphthalene, diethylhexyl phthalate, synthetic pyrethroids and xylene. Volunteers (n=436) were randomly sought by a postal survey based on the UK Electoral Register. Participants were asked to complete a questionnaire and provide a urine sample. The overall response rate was 7.5%, with volunteers being recruited from all areas of the UK including, England, Scotland, Wales and Northern Ireland. Study participants were adults and comprised 45% male and 55% females. We have conducted a simple, postal-based, cost-effective study and generated similar reference values to very large surveys such as NHANES. This demonstrates that large investigations may not be necessary to get a reasonable idea of environmental exposures, especially in initial 'screening-type' investigations to identify particular exposures of concern or to demonstrate that exposures are reassuring low and that no further survey data needs to be gathered.