Assessment of exposure to chemical contaminants in water and food

The main questions on the validity of the studies and routine monitoring (e.g., in the scope of the WHO/UNEP GEMS programme) assessing exposure to chemicals through water and food (i.e., through digestion) relate to the following. (a) Sampling: variations due to sampling strategy and approach usually exceed analytical errors. (b) Measurement: quality assessment and quality control (QA/QC) procedures are essential. However, potential limitations of measurement errors resulting from implementation of these procedures should be kept in perspective with other errors and confounding factors. (c) Methodology: which depends on the variability of the intake patterns in the population, as well on the adequacy of the information on the consumption of food of a specified type as an indicator of the intake of a specific chemical. These factors should be considered in particular in studies using ‘food basket’ methods. Whenever possible, structure of the population in respect to the factors determining typical diet should be registered. (d) Form of reporting: limiting possibilities for re-analysis of the exposure estimates. In conclusion, the routinely collected data on exposure through food and water should be used with care in epidemiological studies. Assessment of the exposure conducted specially for the epidemiological study should consider possible changes of the diet with time. The data on confounders are crucial for exposure estimates.