Ebook Dietary Exposure Assessment Of Chemicals In Food
As the Swiss physician Paracelsus stated in the 16th century, “all substances are poisons; there is none which is not a poison. Therefore, the right dose differentiates a poison and a remedy” (Winter & Francis, 1997). This fundamental relationship between a chemical’s inherent toxicity and the exposure of the population to that chemical forms the foundation for modern risk assessment of potentially hazardous chemicals. Consequently, exposure assessment is essential for quantifying risk and, ultimately, for determining whether a substance poses an unacceptable risk to public health.
The role of dietary exposure assessments has grown significantly in light of the World Trade Organization’s “Agreement on the Application of Sanitary and Phytosanitary Measures”. Paragraph 16 of this agreement requires that sanitary and phytosanitary measures be based on sound scientific risk assessment. The agreement also states that sanitary measures that are consistent with standards, guidelines, and recommendations of the Codex Alimentarius Commission are considered to comply with the requirements of the agreement. This reference to the Codex Alimentarius Commission is based on the underlying risk assessments that support Codex risk management decisions.
Risk analysis for food chemicals is made up of three components: risk assessment, risk management, and risk communication (WHO, 1995a). Risk assessment at the international level provides the scientific basis for the establishment of Codex standards, guidelines, and other recommendations and includes dietary exposure assessments as an essential component. This ensures that safety requirements for food are protective of public health, consistent among countries, and appropriate for use in international trade.
The Codex Alimentarius Commission Procedural Manual (Codex Alimentarius Commission, 2006) defines exposure assessment as “the qualitative and/or quantitative evaluation of the likely intake of biological, chemical, and physical agents via food as well as exposures from other sources if relevant”. The present document deals with dietary exposure assessment of chemicals, including nutrients, present in food. However, some of the principles and approaches described here can have application to biological agents in food as well.
Dietary exposure assessments combine food consumption data with data on the concentration of chemicals in food. The resulting dietary exposure estimate is then compared with the relevant toxicological or nutritional reference value for the food chemical of concern. Assessments may be undertaken for acute (short-term) or chronic (long-term) exposures, where acute exposure covers a period of 24 h (reference) and long-term exposure covers average daily exposure over the entire lifetime. Dietary exposure assessments of nutrients use default assumptions that tend to underestimate exposure, whereas dietary exposure assessments of potentially toxic food chemicals use default assumptions that tend to overestimate exposure. For some nutrients, two assessments may be necessary because of the specific need to look at both nutrient adequacy and the potential to exceed upper safety levels.
CONTENTS
EXECUTIVE SUMMARY
1. INTRODUCTION
1.1 GENERAL CONSIDERATIONS
1.2 DIETARY EXPOSURE ASSESSMENT METHODS
1.3 PRESENTATION OF RESULTS OF DIETARY EXPOSURE ASSESSMENTS
2. DATA SOURCES
2.1 DATA ON CHEMICAL CONCENTRATIONS IN FOOD
2.1.1 Use of maximum levels or maximum residue limits in dietary exposure assessments (pre-regulation)
2.1.2 Use of other data sources for dietary exposure assessments (pre- and post-regulation)
2.1.3 Approaches for obtaining data on chemical concentrations in food
- 2.1.3.1 Supervised trials (pesticide and veterinary drug residues only)
2.1.3.2 Monitoring and surveillance data for chemicals in food
2.1.3.3 Processing studies to refine concentration data for use in dietary exposure estimates
2.1.3.4 Total diet studies
2.1.4 Sampling
- 2.1.4.1 Sample collection
2.1.4.2 Sample preparation and processing
2.1.4.3 Specific design approaches for generating concentration data
2.1.5 Analysis
- 2.1.5.1 Quality assurance
2.1.5.2 Handling non-detected or non-quantified results
2.1.6 Deriving data on chemical concentrations in food for use in estimating dietary exposures
2.1.7 Uncertainty in data on chemical concentrations in food
- 2.1.7.1 Errors in analytical measurements
2.1.7.2 Procedures for estimating measurement uncertainty
2.1.8 Available databases on chemical concentrations in food
2.1.8.1 Food composition data for nutrients
2.1.8.2 GEMS/Food database
2.2 FOOD CONSUMPTION DATA
2.2.1 Food consumption data requirements
2.2.2 Approaches for food consumption data collection
- 2.2.2.1 Population-based methods
2.2.2.2 Household-based methods
2.2.2.3 Individual-based methods
2.2.2.4 Combined methods
2.2.3 Data reporting and use
- 2.2.3.1 Mapping
2.2.3.2 Data format/modelling
2.2.3.3 Food portion sizes
2.2.4 Usual food consumption patterns
2.2.5 Food consumption databases
- 2.2.5.1 Databases collected through population-based methods
2.2.5.2 Databases collected through individual-based methods
2.2.6 Additional data
- 2.2.6.1 Poundage data
2.2.6.2 Body weight
3. ESTIMATING DIETARY EXPOSURE
3.1 INTRODUCTION
3.2 CONSIDERATIONS WHEN UNDERTAKING AN EXPOSURE ASSESSMENT
3.3 STEPWISE APPROACH TO EXPOSURE ASSESSMENT
3.4 POINT ESTIMATES OF DIETARY EXPOSURE
3.4.1 Screening methods
- 3.4.1.1 Poundage data (food additives, including flavourings)
3.4.1.2 Budget method
3.4.1.3 Model diets
3.4.2 More refined deterministic/point estimates
- 3.4.2.1 Correction factors
3.4.2.2 Handling of non-detects
3.4.2.3 Consumer loyalty
3.4.3 Further examples of point estimates using model diets
- 3.4.3.1 GEMS/Food regional diets and consumption cluster diets
3.4.3.2 Total diet studies (TDSs)
3.4.3.3 Modelling high consumers of two food groups
3.4.4 Specialized studies designed to answer specific questions
- 3.4.4.1 Selective studies of individual foods
3.4.4.2 Duplicate portion studies
3.5 REFINED DIETARY EXPOSURE ASSESSMENTS (PROBABILISTIC DISTRIBUTIONAL ANALYSES)
3.5.1 Overview of probabilistic estimates of exposure
3.5.2 Probabilistic models
- 3.5.2.1 Simple empirical distribution estimate
3.5.2.2 Random sampling estimate from food consumption and/or chemical concentration distributions
3.5.3 Applicability of a probabilistic approach at the international level
3.5.4 Uncertainty and variability analysis
3.5.5 Sensitivity analysis
3.6 SPECIFIC CONSIDERATIONS FOR MODELLING APPROACHES FOR ACUTE AND CHRONIC DIETARY EXPOSURE ASSESSMENTS
3.6.1 Chronic dietary exposure assessments
3.6.2 Acute dietary exposure assessments
- 3.6.2.1 Pesticide residues
3.6.2.2 Veterinary drug residues
3.6.2.3 Contaminants and food additives (including flavourings)
3.7 AGGREGATE/CUMULATIVE EXPOSURES
3.8 BIOMARKERS OF EXPOSURE
4. RECOMMENDATIONS
4.1 DATA ON CHEMICAL CONCENTRATIONS IN FOOD
4.2 FOOD CONSUMPTION DATA
4.3 ESTIMATING DIETARY EXPOSURE
5. REFERENCES
ANNEX 1: GLOSSARY
ANNEX 2: LIST OF ACRONYMS AND ABBREVIATIONS
ANNEX 3: LIST OF PARTICIPANTS
ANNEX 4: ACUTE DIETARY EXPOSURE ASSESSMENT ESTIMATES CURRENTLY USED BY JMPR
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