What is XI?

The tool

The XI tool is another application that was developed on request of different users of this portal. For assessing health risks of chemical substances in food or feed it is common practice to calculate intake of the chemical using conservative conditions, such as the highest concentration reported in combination with a high percentile (e.g. 95%) for consumption. Although this is describing a real situation, one should be aware of the fact that such scenario has a very low probability, and might therefore not be representative for the situation to be evaluated. Besides one should be aware that many foods are consumed on a certain day by only a small percentage of the population, thus making the situation of exposure more unlikely for the general public.
A better way to estimate "real" exposure to chemicals from food or feed is to calculate intake of the chemical for each consumer separately. This is, what XI does. The result is a list of numbers, with zero values for non-consumers, and different values for the various consumers. The individual intake per kg bodyweight can then be established using the actual body weight of that consumer in stead of using an average weight. Then the results express the variation of the intakes, making it possible to find values for the median exposure and its percentiles (and to find outliers!). And, to find the factual percentage of the population that exceeds a Health Based Guidance Value.

Monte Carlo

Another speciality of XI is the possibility to use a series of concentrations of the chemical substance for the calculations, in stead of a single number. In this way one can evaluate the full report of a laboratory for a series of samples, rather than select one value from all findings. Now the tool will select the concentrations from the list in a random manner. So, the variation in the consumption of various consumers is combined with the variation of the concentration of the chemical substance in different samples, leading to a better picture of the actual variation of the intake.

Cumulative exposure

XI (as most comparable tools) can only evaluate one chemical substance in one food commodity. For some contaminants however, increased levels will be found in different commodities, e.g. dioxins in milk, and meats, and oils, and fish. In these cases the risk assessor is interested in the total exposure from all food items, rather than exposure from one food. XI can not directly handle such a case directly, but it can help you to calculate the total exposure, as its output is a csv file with an unique id for each consumer. Multiple .csv files can be imported in many computer applications such as spreadsheets, or be read by statistical software (e.g. R and SAS). The intake levels can now be combined to calculate total intake from all relevant foods.

Databases

The first version of XI used a Dutch food consumption database of the period of 2012 to 2016. That version can now be found in the portal's archive. The present version use the consumption database of 2019 to 2021. It should be stressed that these databases refer to the consumption of foods as in the Netherlands only. These data might give a good indication for (northern?) countries with a similar kind of consumption habits, but can be vey different for e.g. southern european countries.

How about your country? If your organization is in the possession of a (national) dataset with consumption patterns of food commodities that you would like to use for intake calculations similar to those of XI, then you are advised to contact the author of this website to discuss the possibility to add your data into the XI tool for similar type of calculations.

How to use

In an additional page more information can be found on how to use XI..