Maximum residue levels in foods
Foods can contain residues from chemicals used in their production, like insecticides or veterinary medicines. Maximum residue levels (MRLs) place a cap on residue levels and ensure food producers and manufacturers follow good practice. Learn more about MRLs and how they're set.
What are maximum residue levels?
A maximum residue level (MRL) is the highest acceptable level of a specific agricultural chemical residue (including veterinary medicines) allowed in food. MRLs are set to ensure good agricultural practices are used to keep residues in food as low as possible.
Under the Food Act 2014, all food produced and sold in New Zealand must comply with New Zealand's MRL standard. Imported foods must comply with the higher MRL from either:
- the international MRL – set by the international food standards body, Codex Alimentarius, or
- the New Zealand MRL.
Food that exceed the applicable limit can't legally be sold in New Zealand.
MRLs help ensure good agricultural practice
MRLs help ensure good agricultural practices are followed during food production. In most cases, foods with residue levels higher than the MRL are safe but may not have been produced in the best way. MPI will investigate any breaches of MRLs and take appropriate action to ensure future production meets the food standards.
Setting an MRL
MPI must approve MRLs for new agricultural compounds or veterinary medicines. Before agreeing to an MRL, our risk assessment managers look at several factors.
- The likely residue levels at harvest, based on using the lowest possible amount of chemical needed to be effective. This residue level determines the proposed MRL.
- The potential dietary intake of foods containing the residue, based on the most recent Ministry of Health's National Nutrition Survey.
- How the potential dietary intake compares with reference health standards (like the acceptable daily intake) for the substance. MPI can accept the proposed MRL if the potential dietary intake is less than the relevant reference health standard.
- Acceptable daily intakes and reference health standards
- Nutrition survey – Ministry of Health website
MPI also looks at results from residue trials representing a range of crop-growing conditions and may set specific requirements for withholding periods and the chemical's use rate.
Withholding periods minimise levels at harvest
A withholding period is the time between when a chemical is last used to when the food can be harvested or an animal can be slaughtered. For example, if an insecticide is only effective against a pest for 2 weeks, the fruit it's used on shouldn't be harvested until 2 weeks after the last use. This ensures the residue is as low as possible at harvest.
MRLs are regularly reviewed
MPI regularly reviews MRLs, including when:
- compounds are to be used in a different way – like in the field instead of a glasshouse or on a different crop
- there's new information on a compound, it has been re-assessed and the reference health standard has been changed
- agricultural practices change.
Find out more
- Food residues survey programme
- Maximum residue levels for agricultural compounds
- Pesticide maximum residue levels (MRLs) for plant products – information for producers
Who to contact
If you have questions about chemical residues in food, email firstname.lastname@example.org.