Controlling residues
What the law says
An MRL (maximum residue level) is the maximum concentration of a pesticide residue that is legally permitted on a particular food. It is an offence for residues in food to exceed these levels. They apply to all food; imported as well as home produced. Most MRL’s are set for the UK but many are set across the EU and this is the long-term aim.
Worldwide, different pesticides may be approved and different MRLs apply. This is because in different climates, different crops are grown that result in different pests.
A controversial example is the use of DDT, which though forbidden in Europe is still permitted in some tropical countries as it is the only pesticide effective against malaria carrying mosquitoes.
It is therefore permitted in those countries on public health grounds. This creates a problem when particular pesticides, irrespective of the crop or its origin.
Any residues above the MRL are an indication that the pesticide has been used incorrectly. MRLs are measured on the crop as it is sold, so include the skin and any inedible parts that would be removed before consumption.
As part of the registration process, scientists set an acceptable daily intake (ADI). These are based on consumption data as well as on the level of pesticide that has no measurable effect. It is an estimate of the amount of pesticide that can be consumed every day of an individual's entire lifetime without causing harm. They include a 100-fold safety factor, so even someone who regularly eats a large amount should be protected.
In assessing the safety of pesticides prior to approval, the MRL is compared with the ADI to ensure there is an adequate safety margin.
How does this protect children and the elderly?
The acceptable daily intake is based on bodyweight, taking into account the difference in size between children and adults. These safety factors go some way to providing additional protection for the greater sensitivity of developing organs.
In addition, for baby foods a very low level of 0.01 milligrams per kilogram MRL has been set. This level cannot be exceeded by any individual pesticide in the finished product.
Who checks for residues in food?