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Label detective: Chemicals in food

Like it or not, the use of chemicals has become a common way to control bugs, diseases and weeds in agricultural production worldwide.

The use of chemicals ensures more consistent quality of production and minimises harvest loss.

What is the law?

To protect consumer health, the Ministry for Primary Industries (MPI) establishes maximum residue levels (MRLs) for chemicals used in agriculture.

An MRL is the highest amount of chemical residue that is permitted to be in a food product. In food, MRLs are set to keep residues from chemicals as low as possible and to ensure that good agricultural practices are followed by producers.

Where’s the line in the sand?

In New Zealand, the MRLs for all foods of plant origin that are produced, imported, or exported must comply with the MRL standards set by MPI. This means the residue levels of particular chemicals in food must not exceed the MRL specified. Exported foods are also required to meet the destination country’s MRL requirements (which could be different to NZ requirements).

Consumer tip

Find out what chemical residues are permitted in your food by visiting the MPI website to access the MRL notice. You can also read the annual survey reports to find out what monitoring activities are being carried out by MPI.

Consumers want fresh produce, but some are worried about chemicals from sprays. Simpson Grierson food law specialists investigate the rules around residues.

Why the different levels for different foods?

In approving MRLs for new chemicals, MPI looks at several factors such as:
• Expected residue levels when harvesting the food (based on the lowest amount required to be effective). This level will determine the proposed MRL.
• Potential dietary intake of foods containing the residue.
• How the potential dietary intake compares with health standards (such as the acceptable daily intake) for the chemical.
• Results from trials incorporating a variety of agricultural conditions.

MPI also regularly reviews MRLs, especially where changes occur in agricultural practices, where chemicals are used in different ways, or if new information about a chemical is available.

In order to ensure compliance, MPI implements food monitoring programmes which enable them to determine if food is staying within the chemical residue safety limits. MPI’s monitoring programme includes the use of surveys where samples on the domestic market are collected for testing. Food producers are not targeted, rather the surveys target foods that may present chemical risks. The surveys typically test for 200 to 500 different chemical compounds.


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