Week 2 - Pesticides and Nanoparticles

Question 1

T or F : nanoparticles are smaller than cells and smaller than bacteria

Answer 1

true

Question 2

T or F : nanoparticles are not allowed as food additives

Answer 2

false. There is titanium dioxide, iron oxides, metallic silver.. etc.

Question 3

T or F : nano additives may contain an unknown percentage of the material in nano form since current specifications do not define limits

Answer 3

true

Question 4

What are the different applications for nanofood ?

Answer 4

1- additives
2- nanoparticles for increasing the bioavailability of nutrients
3- Nanomaterials for the food packaging (antimicrobial, improved barrier, tracing and monitoring the conditon of food during transport and storage)

Question 5

What is the definition of nano food?

Answer 5

any intentionally produced material that has one or more dimensions of the order of 100 nm or less including structures, agglomerates or aggregates, which may have a size above the order of 100 nm but retain properties that are characteristic of the nanoscale“

Question 6

Why is size important in the case of nanoparticles ?

Answer 6

because the smaller the size, the more reactive the particle since the reactions occur at the surface of particles. So it is not the size per se but the surface volume. Also there is dissolution rxn that happens at the surface

Question 7

What is the definition of an aggregate in the case of nanoparticles ?

Answer 7

A group of particles held together by strong forces such as covalent or metallic bonds.

Question 8

What is the definition of an agglomerate in the case of nanoparticles ?

Answer 8

Agglomerate are group of particles held togther by weak forces like van der waals forces, some electrostatic forces or/or surface tension

Question 9

T or F: the particles in the aggregates can be detached and found loose since they are loosely bound

Answer 9

false, particles in aggregates are held together by strong forces

Question 10

What are the various forces that can ditacte the behaviour (aggregate/agglomerate or loose particles) of nanoparticles

Answer 10

1- van der waals forces
2- steric repulsion
3- electric double layer (EDL)

Question 11

What are the dynamic conditions in the GIT that influences the behaviour of particles ?

Answer 11

1. pH
2. Ionic strenght
3. Anaerobic conditions
4. presence of food

Question 12

T or F : agglomerates are dynamic

Answer 12

true, depends on the conditions of the environment if the nanoparticles will be in the free or agglomerate form

Question 13

What are the various form that the nanoparticles can present themselves in the GIT

Answer 13

1. They can be dissolved because of the pH (silver ions)
2. They can be surrounded by proteins (protein corona)
3. They can be in the free form or as agglomerates (depends on the pH)

Question 14

What are the proposed route of uptake of nanoparticles

Answer 14

1. normal transcellular through the enterocytes
2. Paracellular transport (between enterocytes)
3. Payer’s patches (PP) which are intestinal lymphatic tissue containing M cells which are specialized in phagocytosis (most probable one)

Question 15

What are the properties that influences uptake of nanoparticles ?

Question 16

what is the proposed mechanisms of toxicity of nanoparticles?

Answer 16

1. dissolution of the ions when the particle is phagocytosed because of the low pH (silver and silicon NP) leading to the continuous release of ions in the cells which is toxic.
2. Frustated phagocytosis : when particles are too large or have fiber like appearance (esbestos like) they can’t be degraded and the fiber ges elongated and this lead to a lot of local inflammation

Question 17

T or F : nanoparticles are also unavoidable contaminants since they are found in the environment.

Answer 17

true

Question 18

What is the approach used by EFSA for the analysis of the safety of nanoparticles

Answer 18

Tiered approach

Question 19

T or F : The potential impact on human health and the environment needs to be evaluated before entering the market

Answer 19

true, it needs to be done for the operators, the workers, the bystanders, the consumers and the non-target organisms ni the environment.

Question 20

What is the data required for the evaluation of pesticides by EFSA ?

Answer 20

1. ADME
2. Acute / short term and chronic toxicity data
3. Genotoxicity / carcinogenicity
4. Reproduction and developmental data
5. Neurotoxicity, immunotoicity, mode of action

Question 21

What does ArFD stands for ?

Answer 21

Acute reference dose. It is used for acute exposure while ADI is used for chronic exposure

Question 22

What si the formula of the ArfD ?

Answer 22

ArfD = NOAEL x 1/10 x 1/10 x other UF

Question 23

T or F : usually the studies for the risk assessment are done on the operators that use pesticides

Answer 23

true, they are used to set the Acceptable operator exposure level (AOEL)

Question 24

What is the AOEL ?

Answer 24

acceptable operator exposure level (AOEL) and it is the maximum amount of active substance to which the operator may be exposed without any adverse health effects.

Question 25

T or F: a big factor of intraspecies differences is used in the case of the study of pesticides because the studies are primarly done on men

Answer 25

false, the exposure is more homogenous than in the general population so the intraspecie factor is reduced from 10 to 3 or 2.5

Question 26

What is the risk assessment steps applied to pesticides ?

Answer 26

the same as what is applied for other chemicals by EFSA.

Question 27

What is MRL ?

Answer 27

Maximum residue limits (MRLs) it is an approach specifically used for pesticides : The higest level of a pesticide residue that is legally tolerated in or on food / feed when pesticides are applied correctly (good agricultural practice (GAP)

Question 28

T or F : if you follow the GAP, you will have residues that are lower than the MRL

Answer 28

true because the MRL as set by trials using the GAP and appropriate pre-harvest interval (PHI) or withholding period (WHP)

Question 29

T or F: the MRL are defined based on toxicological assessment and are safety limits

Answer 29

false, they are driven by the fact that we want to use the minimum level posisble but they are in line with toxicological threshold. They are usually well below the tox. threshold (ADI) and if not then the agricultural practices are changed because the number only relfets the level of pesticides minimal to acheive sufficient results.

Question 30

T or F : the MRLs are fixed by the european commission

Answer 30

True

Question 31

T or F : for pesticides that are not explicitly mentioned in the set document in 2008, a defaut MRL of 0.01 mg / kg is used

Answer 31

true

Question 32

MRL are fixed by ____

Answer 32

european commission

Question 33

T or F : Exceedance of MRL is legally not allowed but does not necessarily imply exceedance of ADI or ARfD!

Answer 33

true, and product can be removed from the market although they do not exceed the ADI / ARfD

Question 34

Name the cases in which the pesticides in the products could exceed the MRLs

Answer 34

When GAP is not respected since both are closely related. So this can be because of :

1. Unauthorised pesticides use
2. Pesticides not authorised for a specific crop
3. Higher application rate or shorther pre-harvest intervals
4. Accidental drift or insufficient washing out

Question 35

T or F : most products in the NL are exceeding the MRL

Answer 35

false, only 4% exceed the MRL, but remember that this has nothing to do with the EDI, ADI or ARfD

Question 37

What were the products with the most excedance of MRL (evauated by EFSA) ?

Answer 37

fruits and nuts
Vegetables

Question 38

What is the mode of action of fipronil (egg incident example)

Answer 38

fipronil was used as a lice txt in chickens and it is a GABA blocker. It is not allowed in the food production anymore but the eggs were removed because they contained it although they contained less than the ARfD. So the exceedance of the MRL is not necessarily a risk, it is only a legal threshold.

Question 39

There is a high exceedance of the acute dose (ArfD) for ____ and ___in peppers and grapes for adults but mostly children

Answer 39

carbendazim residues and carbofuran residues

Question 40

Exposure to ____ pesticide residues in eggplant and cauliflower is not a problem because it does not exceed the ARfD

Answer 40

true

Question 41

The exceedance of diazinon is mainly due to ___ and ___

Answer 41

apples and wheat

Question 42

t or f : the long term exposure are not a problem but the short term exposure to pesticides

Answer 42

true

Question 43

The highest exceedances of toxicological reference values for each of the following are due to :

● carbofuran residues in ___

● oxamyl residues in ____

● monocrotophos residues in ____

● methomyl/thiodicarb residues in ____

● dimethoate/omethoate residues in ___

Answer 43

carbofuran, oxamyl residues, monocrotophos and methomyl due to peppers
dimethoate due to grapes

Question 44

T or F : for pesticides there is no combination toxiciology approach used for their approvoal but for there is for the risk assessement

Answer 44

yes and this is problem because their could be synergism if the same mode of action for the pesticides. For the risk assessment , the cumulative risk assessement approach using the relative potency factor (RPF) is used.