Dit is het oefententamen van het vak Food Toxicology , Alle antwoorden staan bij de vragen. Daarnaast staan er nog 55 extra (korte) vragen in het tentamen die ingaan op de stof.
Food toxicology practise exam
Question 1. Food contains avoidable chemicals that require safety and risk assessment. For this often
an ADI is used.
1. What is an ADI and how is it achieved that it protects also the most sensitive individuals. (2
points)
ADI is the acceptable daily intake. It is the amount of compound/substance that can be
consumed daily without getting any adverse health effects. The most sensitive individuals are
protected because the ADI is established using the uncertainty factor of 100 (2 times 10). The
uncertainty factor is used to extrapolate from an animal population to human population and
from human population to the most sensitive subgroup human population, so even the most
sensitive human population is taken into account.
2. Why can the outcome of risk assessment be that a compound with a hazard is safe? (2 points)
Because the daily intake (EDI) is far below the LOAEL, the dose where health effects may
occur. The MOE can also be really high > 10.000. in this case there is no health concern.
3. Why is it unlikely that an avoidable chemical in food is genotoxic? (2 points)
Avoidable genotoxins are not allowed to be present in food products. These compounds are
forbidden.
4. When intake exceeds the ADI the EDI should be lowered. Why is in such a situation the ADI
not defined at a higher level to solve the problem? (2 points)
ADI = Acceptable daily intake
EDI = estimated daily intake
The ADI is established using toxicological information about the substance (using the NOAEL
or BMDL) to apply the uncertainty factor of 10/10. This calculation will give the estimated
dose that will used daily not give any health (adverse) effects. If the ADI would be defined
higher the whole risk assessment will not be correct anymore.
5. When a NOAEL or BMDL10 can be derived from human data that are derived from a large
population representing the overall population what uncertainty factor would then be used
to define the ADI? (2 points)
No uncertainty factor will be used in this case, because there is interspecies difference
anymore because there is human data available and the most vulnerable subpopulation is
already taken into account because the population represents the whole population.
Question 2. In modern risk assessment we prefer use of the BMDL instead of the NOAEL (No
Observed Adverse Effect Level) to define safe levels of exposure.
1. What is a BMDL (1 point) and how is a BMDL derived from the experimental dose-response
data (1 point)?
The Bench mark dose is the minimum dose that causes a predetermined change in adverse
health effects. For example BMDL10 is the minimum dose that will cause a 10 increase in
health effects.
2. Why do you need to use the BMDL for the critical effect in the target organ to define a safe
level of human exposure?
The target organ is the most sensitive organ. If the target organ is safe, the rest of the body
will also not be effected.
3. Mention 3 important advantages of using the BMDL instead of the NOAEL in risk assessment
(2 points).
Advantages of BMDL:
- BMDL is not limited to the dose
, - The factors that can influence the variability of the results are taken into account. This is
not taken into account with the NOAEL approach
- The BMDL’s in different studies are quite similar, this is not the case for the NOAEL
4. Explain why a bad study design with only a few animals in a dose group will result in a lower
BMDL and thus a lower ADI (2 points).
If there are only a view animals participating to the study, the chances are higher the dose
will be set higher because there can be less sensitive animals present. This will give a wrong
indication of the NOAEL or BMDL
5. What uncertainty factors do you have to use when using a BMDL05 instead of a NOAEL to
define an ADI? (2 points)
The same UF: 100 (2 times 10)
Question 3. In the modern food chain there are several avoidable compounds that require risk and
safety assessment, including food additives, pesticides and food flavours.
1. An ARfD (acute reference dose) defines a safe level of acute exposure to a pesticide; why is
an ARfD defined for pesticides but generally not defined for food additives? (2 points)
Food additives are used in really small amounts in food products and pesticides can be used
in higher amounts and operators can be exposed to high amount which can maybe cause a
acute exposure, this is not the case with food additives.
2. Which two types of potential adverse effects of food additives raise most concern among
consumers and describe for each issue in one sentence the current state-of-the-art with
respect to the assessment of this hazard or risk. (2 points)
1. Carcinogens (cancer formation): low risk, this is well studied before an additive can be
used in food products, if a food additive is genotoxic or carcinogenic it is not allowed to
be used in the food industry.
2. Behaviour changes (in children): not as well studies, more research has to be done. In the
EU there is only a warning on some products.
3. Why did EFSA conclude that the results of the so-called Southampton study, testing a mixture
of synthetic food colours and benzoate, could not be used to modify the ADI of the food
colours tested? (2 points). Risk and safety assessment of flavours and food contact materials
is done in a different way than that for food additives.
4. One difference is the use of the TTC approach in the safety evaluation of flavours. What is a
TTC and how can it be used in risk assessment of food flavours? (2 points)
TTC= Threshold of toxicological concern. This is the level of exposure in humans that is
considered to be of negligible risk.
5. Risk assessment of flavours also uses read across; explain when and how that is used in the
risk and safety assessment of food flavours (2 points)
Read across is the use of toxicological information of a compound that has almost the same
structure, because there is no or to little information available about the compound for
which one is information needed. No further research is than required
Question 4. Food may contain several carcinogens.
1. Mention two important reasons that explain the presence of carcinogens in food. (2 points)
- Naturally occurring toxins can be carcinogens (mycotoxins and phytotoxins)
o PA’s
o Alkenylbenzenes
- Can be formed during heat processes
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