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Summary of lectures/knowledge clips week 3
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I made a summary of all lectures and knowledge clips of week 3. I included sometimes some slides, to give more clarity to the text.
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Week 33.1a Clip pesticides
Pesticides is in avoidable chemicals.
Pesticides protect food and non-food crops against:
- Insects (insecticides)
- Fungi (fungicides
- Weeds (herbicides)
- Other biological causes
These pesticides may end up in our food chain. Before pesticides end up on the market, risk
assessment is needed, as the can cause adverse effects to humans and environment.
Risk assessment is done for:
- Operators: persons who apply the pesticides
- Workers: who work in treated crops or (storage) rooms
- Bystanders: persons that are present near places where pesticides are applied
- Consumers: general population
- Non-target organisms: in the environment
Pesticide risk assessment consumers:
ADI = acceptable daily intake, safe level of exposure for chronic exposure.
Derived from NOAEL or BMDL05
ArfD = the acute reference dose, safe exposure level for acute exposure
Pesticide risk assessment operators:
AOEL = acceptable operator exposure level the maximum amount of active substance to which
the operator may be exposed without any adverse health effects.
- Based on short term studies, not based on long life exposure
- Safety factors applied are lower compared to whole population (elderly and children don’t
work with these pesticides). So, the population exposed are more homogenous than general
population intraspecies factor reduced from 10 to 3 or 2.5.
, Dietary exposure = concentration chemical on the products that we eat * amount of food that is
consumed, so residue concentration * foods consumed.
Maximum residue limit (MRL): The highest level of a pesticide residue that is legally tolerated in or
on food or feed when pesticides are applied correctly (Good Agricultural Practice (GAP).
With paying attention to:
- Maximum number of applications
- Maximum application rate
- Shortest time to harvest (time from application to harvest)
Different field trials are performed, pesticides applied according to GAP and then find out
what the levels of pesticide are left on the crops. The highest found value and that can be
used as MRL.
The MRL:
- Is not a toxicological safety limit
- It reflects the use of minimum quantities of pesticides to achieve sufficient effectivity
- It is checked if MRL would result in intake that remains below the ADI, if so: ok; if not: modify
agricultural practice
- In most cases MRLs are well below the toxicologically maximum acceptable concentration
- MRL is used to check pesticide residue levels in food products residue levels above the
MRL cannot be placed on the market
- MRLs are fixed by the European Commission (after 2008 harmonised)
- If no MRL available a default MRL of 0.01 mg/kg is applicable
- Exceedance of MRL is legally not allowed but does not necessarily imply exceedance of ADI
or ARfD!!!!
MRL exceedance:
- unauthorised pesticides
- pesticides not authorised for a specific crop (some can only be used for a specific crop)
- higher application rate or shorter pre-harvest intervals
- accidental drift or insufficient washing out (pesticides can move to other fields due to wind
etc.)
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