Review of learning (with)
Total diet studies: What they are and why they are important (Monday, 6th July 2015, 09.00-10.30)
1. What are some of the challenges in protecting the public from risks posed by chemicals in the food supply?
- Because low levels of chemicals cannot be detected by taste or smell, consumers must rely on the government ensure that food supply is safe
- Unlike microbes, chemicals cannot generally be destroyed or removed from food once it is contaminated
- Adverse effects caused by chronic exposure to chemicals often appear slowly over months, years or even decades
- While hazard characterization applies to populations everywhere, chemical exposure assessment is unique for every population and cohort
- Exposure assessment of the large number of chemicals in the food supply is technically demanding and expensive
- Chemicals are perceived by consumers as highly dangerous possessing a number of negative risk-perception factors, such as dread of the adverse effects, e.g. cancer, birth defects
- Disease outbreaks (e.g. poisonings) and contamination incidents occur periodically and are given a high profile in the media
- The international food trade network poses intractable risks from chemicals in the food supply chain
2. What are the main advantages of total diet studies in assessing dietary exposure to chemical?
- Foods are analyzed “as consumed” providing the best estimate of actual exposure.
- Depending on the availability of consumption data, mean and high percentile exposures for a population and selected cohorts can be calculated.
- A range of chemicals can be evaluated in one study, including food additives, pesticides, veterinary drugs, naturally occurring contaminants, environmental contaminants, processing contaminants and nutrients.
- Periodic total diet studies can provide baseline information on the levels and trends of chemicals in the food supply.
- Total diet studies are perhaps the most cost-effective method for obtaining dietary exposure information.
- Total diet studies are simple and easy to understand for risk managers and consumers in general
Criteria for selection of chemical substances and population targets (Monday, 6th July 2015, 11.00-12.30)
1. What typologies of populations can be targeted in a TDS?
- Population more sensitive
- Population more exposed because of specific needs, specific diet or of a contaminant environment
2. What are the main steps of the HAP method?
- Identifying priority problems and targets
- Identifying the criteria to be used to compare the various actions
- Defining the relative weights for criteria
- Making list of alternatives (substances) among which we want to make a prioritization
- Evaluating the importance of each alternative (substance) for each criteria
- Aggregation of all judgments
Science Communication (Monday, 6th July 2015, 16.00-18.00)
1. What is the difference between dissemination and communication?
- Dissemination broadcasts information to stakeholders with no expectation of a response or dialogue
- Communication engages some or many stakeholders in a dialogue
2. What are the five Ws and 1H?
- Who, when, where, what and why, and how
3. What is the primary difference between how scientific publication deliver information compared with other sources?
- Science publications (triangle): introduction, methods, results, discussion, conclusions
- Other publications (inverted triangle): conclusions, discussion, results, methods, introduction
Planning a Total Diet Studies (Tuesday, 7th July 2015, 09.00-10.30)
What are the core components in a TDS planning?
- There are at least three main components: objectives, management, and methodology
Sampling plan for a TDS and its relation to the food list (Tuesday, 7th July 2015, 11.00-12.30)
1. What are the most important issues to remember concerning sampling?
- Sampling is done to fulfil a purpose
- Done to represent foods and their composition ‘as consumed’ by the study population
- Avoid changes in composition from collection to analysis
- Detailed knowledge of the foods and their composition is needed to make appropriate sampling decisions
- Sampling errors should be avoided
2. What are the two disadvantages of pooling?
- Dilution effect (smoothing effect): i.e. when a highly contaminated food item is combined with several less contaminated foods, the pooled samples will have little or no measurable contamination. If foods are pooled to a high degree, the level of the contaminant in the food sample might be so highly diluted that the level of the whole food sample becomes negligible and/or drop below measurable levels. Even if a contamination is detected it would be impossible to define mitigation measures as it is not possible to determine which food(s) in the pooled sample contributed to the contamination, unless sub-samples of the primary foods were retained in storage and analysed individually. The smoothing effect is similarly applicable for nutrient analyses.
- Limits the ability to calculate dietary exposure of different population groups as in each pooled sample, the relative amounts of each are fixed and might correspond to one population group. For other population groups who consume different relative amounts of the foods, a new pooled sample would be needed or their exposure cannot be estimated.
Developing a TDS food list to compose TDS samples (Monday, 6th July 2015, 14.00-15.30)
1. Which criteria are fundamental for formulating a TDS food-shopping list representative of a reference diet in a population group?
- Identification of core foods potentially containing substances of concern
- Aligning dietary data and core foods; food description and food coding systems
2. Which tasks are necessary to transform a TDS food list in a TDS food-shopping list?
- Designing the sampling plan (where, when to purchase food products)
- Acquiring market share data / information on varieties (which products)
- Procedures for food products selection
3. Why is recording food information important?
- Tracking the composition of a market basket to better interpret the results
- Using the information for future studies
- Enhancing the cross-country comparison
4. How many “main” steps are in a protocol for collecting food products for a TDS?
b) 3 (correct answer)
c) More than 10
5. The more detailed is the food consumption list the better is represented the reference diet
a) True or b) False – correct answer is (a) True
6. Food description and coding are
a) Independent tasks
b) Conflicting tasks
c) Each is helpful to perform the other (correct answer)
7. Advantages in recording food shopping list data
a) It makes possible to retrieve information to enhance the interpretation
b) It makes possible to enhance the cross-study comparability of the results
c) Both the options above (correct answer)
Food collection for TDS – Sampling plan (Wednesday, 8th July 2015, 09.00-10.30)
1. What are the main features that characterize national respectively regional foods?
National foods, including processed foods, are likely to present homogeneous contamination levels in all regions, i.e. food is produced in one factory, by one manufacturer, which delivers across the whole country. Regional foods include foods that are expected to differ in levels of the investigated chemical substances due to e.g. environmental factors like levels of substances in soil, local contamination, regional/local climate, differing species/varieties produced, agricultural practices (fertilisers, pesticides used), or different supply pattern among regions.
2. Which information about sampling and sampled food items is useful to register into collection report?
- Food identification (code, name of the product, brand,…)
- Expiry date indicated as “best before” or “use by” date
- Sample size (weight, volume, units);
- Who, when a where bought a food item(-s)
- Costs of the samples
- Any deviations from the sampling instructions should be recorded
Food consumption data and their use in dietary exposure assessment to contaminants (Tuesday, 7th July 2015, 14.00-15.30)
1. What are the main needs in term of food consumption data in order to perform an exposure assessment?
In order to perform an exposure assessment, it is important the food consumption data to:
- Cover the variability of food consumption patterns within the population, in order to characterize not only the average consumption level, but also the high percentiles (persons who eat high amount of one given food),
- Cover the target populations, i.e. the ones which are expected to be most sensitive in regards to the adverse effects associated with the hazard (chemical/microbiological agent) of interest,
- Take into account a single eating event or the total amount of food consumed during one day (short-term/acute exposure) but also the usual habits of food consumption over days (long-term/chronic exposure),
- Food to be described very precisely. The information required will vary according to the kind of chemical compounds. For example, the cooking procedures is important for chemicals which appear during cooking process (ex: acrylamide), the packaging for food contact materials (ex: bisphenol A), sugar/sugar free (ex: aspartame), with/without additives (colours, flavours), etc…
2. What are the main sources of food consumption estimates?
There are three main sources of data, each of them with their advantages and drawbacks. One first source of data are food balance sheets (FBS), which describe the amount of foods available for human consumption per capita at the country level. These data can be freely uploaded from the FAO website. FBS mostly cover raw agricultural commodities and semi-processed foods. They provide a single estimate at the population level, without any indication of the variability of consumption within the population. They are currently the unique source of comparable data throughout the world (GEMS/Food Consumption Cluster Diets). They can be useful especially when looking for consumption estimates for rarely consumed foods, which are not well captured by the other sources of data. The second source of data are the purchase records from consumer panels, which describe the amount and kind of foods purchased at the household level. Purchase records cover both raw agricultural commodities and processed foods, but don’t take into account preparation of food as consumed and wastes at home. They allow to take into account variability but only at the household level. They are an interesting source of information for brands and packaging, and can complement the individual food consumption surveys in this regard. Such data can be obtained from market research companies. The individual food consumption surveys are the most refined source of data in the exposure assessment. They provide consumption estimates of foods as consumed at the individual level and aim to be representative of the target population. They are mostly collected either via food records (prospective tool) or via food recall (retrospective tool) and can be completed by food frequency questionnaire in order to better characterize the consumption habits of rarely consumed foods. Summary statistics of individual food consumption data from 22 European countries (EFSA Comprehensive European Consumption Database) are currently available on the EFSA website.
Sample preparation and culinary operations (Tuesday 7th July 2015, 16.00-17.30)
1. What is the guiding principle and the single most important aim of food preparation done in the TDS kitchen?
To prepare each food sample is a way that replicates faithfully the food preparation methods used by consumers, so that the food that is subsequently analysed (as such or as part of a pooled composite) has exactly the same concentration of the target chemical(s) as the consumer would eat.
2. What are the advantages and disadvantages of using tap water in the reconstitution of dehydrated foods and for cooking in the TDS kitchen, compared to the alternative of using distilled or deionised water.
Advantages. Including tap water ensures that any minerals from the water are included in the final food. Tap water is cheap and freely available. Using tap water ensures that the leeching of substances when foods are eg boiled, is representative of home-cooking. Disadvantages. Tap water varies from region to region. Some consumers may not use tap water; they may use bottled water in the kitchen or use tap water that has been treated with a jug filter with an activated carbon filter and an ion exchange filter.
Analytical measurements: what’s behind the numbers (Wednesday, 8th July 2015, 11.00-12.30)
1. Briefly describe how the dioxin concentrations are determined in a fish composite sample. What kind of meta-data will help you to assess the quality of the numbers given to you?
(i) Procedure: sampling, pooling, homogenization, extraction, clean-up, instrumental measurement, data interpretation, (ii) sample intake used, blank measurements, validated method, accredited lab, work according to ISO 17025, proficiency testing, CRM analyzed, validation data/method parameters (precision, trueness, total measurement uncertainty, composition of uncertainty budget,…). Not all the info has to be available, but the more the better. Having only a number does tell you much.
2. What are the two main approaches in how an uncertainty budget can be established? How can one assess whether a reported uncertainty is realistic or not? And how can an uncertainty be lowered if necessary?
Bottom-up and top-down approach (cfr slides). In general the uncertainty of a measurement is inversely correlated to the reported mass fraction. This gives already a first indication on the quality of a stated uncertainty. Further, the accuracy of an uncertainty budget can be assessed if information on the contributing parameters to the uncertainty budget are available. What aspects are considered to establish the budget and to what extent? Does it only include the variation on the actual measurement (precision) or does it also encompass intermediate precision or even reproducibility? Is bias included (based on CRM measurements)? The more comprehensive the estimation, the more realistic the budget will be. In most cases however uncertainties tend to be underestimated. Uncertainties can be reduced and the measurement accuracy increased. By increasing the number of replicates random errors can be reduced (but also significantly increasing the cost of the analyses); having 2 replicates does not add much value. Systematic errors need more profound measures and will necessitate further method optimization which might not always be possible.
Systems for describing food – LanguaL/FoodEx (Wednesday, 8th July 2015, 14.00-18.00)
1. What is the central feature of FoodEx2?
The core food list (or core and extended food list) produced by EFSA for exposure assessment
2. What is the main purpose of LanguaL?
To describe, capture and retrieve data about food
3. Which FoodEX2 facet type and facet code would be used for a ‘smoked’ food and what is the associated Langual code?
- Preservation technique facet
- Preservation with substances/ingredients [A0C0N], smoking [A07JV];
- H0172 Smoked or smoke flavoured
4. How can a LanguaL term be added or amended?
Make a proposal to the LanguaL technical committee
FoodCASE in the context of food data (Thursday, 9th July 2015, 09.00-10.30)
1. What is the advantage of using an electronic information system to manage TDS data in comparison to a basic tool such as EXCEL or ACCESS?
- Data can be manipulated by multiple users at the same time
- Data management is centrally organised and access control is in place
- Data quality checking is available and can be extended as needed
- Data can very easily be published on a website over the information system
- Several import and export formats are available to exchange data
- Tracing of data changes (=data auditing) is in place
- Automatic operations such as spreading compound values to all ingredients of a pooled food can be performed (automatic operations are less error prone than manual operations)
- If the system also contains food comp data and food consumption data then these information can all be linked
2. Describe the basic steps of TDS, and explain how FoodCASE-Risk covers these steps including missing elements
- Create food list / search food items in FoodCASE
- Create shopping list / search food items filtered and sorted by consumption information
- Perform food sampling / document food sampling under each food
- Prepare foods /document food preparations under each food
- Pool foods / create new pooled food items with ingredients
- Anlayse pooled foods / document analytical results under each food
- Spread analysed values to all ingredients of pooled foods / execute spreading function
- Export data for risk analysis / export data in a given format
Quality Management Principles and Practices suited to TDS (Thursday, 9th July 2015, 11.00-12.30 & 14.00-15.30)
1. What is the difference between harmonization and standardization?
- Standardization deals with conformity (fulfilment of a requirement laid down in a standard (e.g. determination of Arsenic according to EN 15763. (2009)
- Harmonization is about consistency and dealing with goals and outcomes (methods to determine a chemical substance with a Limit of Detection better than 60 mg/kg)
2. What are the sections and steps of TDS flowchart and associated quality documents?
- Step 1 up to 9 – Planning a Total Diet Study (TDS G D 01)
- Step 10 up to 17 – Executing a Total Diet Study
- Step 10 -Preparation for food collection, sample preparation and analysis (TDS SOP1)
- Step 11- Collection of samples (TDS SOP2)
- Step 12 -Reception of individual samples (at kitchen laboratory)(TDS SOP3)
- Step 13 -Sample preparation (at kitchen and analytical laboratory) (TDS SOP4)
- Step 14 -Chemical Analysis of Laboratory samples (TDS SOP5)
- Step 15 -Exposure assessment (TDS GD02)
- Step 16 – Risk Characterization (TDS GD03)
- Step 17 – Risk Communication and Publication of results (TDS GD 04)