The limit of determination (LOD) is the lowest concentration of a pesticide residue that can be measured using routine analysis.
Analytical methods for all pesticides must be sufficiently sensitive that residues below the LOD can be regarded as unimportant.
Circumstances in which Maximum Residue Levels (MRLs) may be set at the LOD
Proper use of a pesticide can leave small traces of residue on the commodity at harvest. Therefore many MRLs are set above the LOD. There are, though, three possible reasons why the MRL might be set at the LOD:
- a particular use is not ‘supported’ in the EU – either because insufficient data have been provided or because no use is intended.
- scientific data shows that the intended use might leave residues that would pose an unacceptable risk to consumers.
- scientific data shows that the intended use leaves no determinable residues on the treated commodity at harvest. This could be in cases where for example the pesticide is used at early stages of growth as a pre-emergence herbicide, or as a seed treatment.
In the first two examples, the MRL is set at the LOD to help ensure that the pesticide is not used illegally on this commodity.
In the last example however the MRL is set at the LOD to help ensure that the pesticide is used correctly on this commodity. Hence, an MRL at the LOD does not necessarily mean that the pesticide use is illegal.
In the majority of cases an MRL set at the LOD reflects the fact that there are no approved uses of the relevant chemical on that crop and crops which exceed that level cannot be imported. However, an MRL at the LOD does not always mean that the pesticide use is illegal.
Reinstatement of an approval
An MRL set at the LOD does not preclude approval for the use concerned being reinstated. Approval could be granted for use so long as data can be provided to show that use would not result in residues above the LOD. This also applies for new uses where the residue levels will exceed the MRL. An application with the supporting data will need to be submitted to the Approvals Secretariat Applications sift (see 'The Applicant Guide: Maximum Residue Levels and Import Tolerances' for further details).
MRLs and approved uses
MRLs provide a mechanism to ensure that pesticides are used correctly. They are not and should not be used as an indication of whether a particular pesticide is approved for use on a particular commodity.
Contact Information
Contact our Communications Branch on 01904 455775 or e-mail: pesticides@hse.gsi.gov.uk for information on product approvals.
You could also contact the marketing company for the product if in doubt as to whether a compound can be used on a certain crop. The contact details for the marketing company appear on the product label.
