Farmers use herbicides to reduce weeds in their crops. Herbicides, together with herbicide tolerant crops, allow farmers to selectively destroy weeds without damaging the main crop.
Genes for herbicide tolerance can be introduced into crops using either conventional plant breeding or gene technology. Conventionally bred herbicide-tolerant crops are grown in both Australia and New Zealand, and genetically modified (GM)
herbicide-tolerant crops are also grown in Australia. No GM crops are currently grown commercially in New Zealand.
Examples of conventional (non-GM) herbicide tolerant crops include triazine-tolerant and imidazolinone-tolerant canola and imidazolinone-tolerant wheat. Herbicide-tolerant GM cotton and canola, licensed for growing in Australia, are tolerant to herbicides such as glyphosate and glufosinate.
All GM foods must be assessed as safe and approved by FSANZ before they can be sold in Australia and New Zealand. The
pre-market safety assessment used for foods from herbicide-tolerant GM crops is the same as for other GM foods but also includes consideration of the safety of any novel metabolites that may be produced in the GM plant after a herbicide has been sprayed.
The GM food safety assessment does not determine the amount of herbicide residue that is allowed to be present on a GM food. This is done separately in a process that applies to both conventionally bred (non-GM) and GM crops.
Residues of agricultural and veterinary chemicals can only legally be present on food if they comply with maximum residue limits
(MRLs). MRLs specify how much residue is allowed to remain in a harvested crop after the chemical has been sprayed and ensures that residue levels are kept as low as possible. The same MRL applies whether the food comes from a non-GM or GM crop.
Regular monitoring by FSANZ of residues in ready-to-eat foods shows that residue levels are generally very low and do not pose any health concerns to consumers. Regular monitoring of residues in raw agricultural commodities is undertaken by other government agencies for compliance purposes. This monitoring shows that MRLs are very rarely exceeded. If an exceedance is found, it is reported to the relevant enforcement agency.
What is a herbicide metabolite? When crops are sprayed, the herbicide is typically broken down within the plant to other substances, known as metabolites.
What is a herbicide residue? When crops are sprayed with herbicide, a small amount of the herbicide or its metabolites might be left on the plant at the time of harvest – these are known as herbicide residues.