The New Zealand Food Safety Authority (NZFSA) is investigating the use of the banned pesticide, endosulfan, which has been found in locally-grown cucumbers.
The residue turned up in samples of the vegetable tested as part of the Authority's Food Residue Surveillance Programme, which found most produce had complied with standards.
Endosulfan was banned in January last year, but NZFSA spokesperson Paul Dansted says there is concern growers may still be using the pesticide and it is investigating.
The same survey also revealed chemical residues in bok choi that were above allowable levels, but Dr Dansted says the produce tested as part of the survey is safe to eat.
Horticulture New Zealand's spokesperson Leigh Catley says growers know what the rules are and should be complying with them.
Ms Catley says the organisation believes it conducted a good education process for growers when the pesticide was banned, and it will continue with this.
The Soil and Health Association disputes the view there is no health risk, and spokesperson Steffan Browning, says there are very few penalties for growers who exceed the maximum residue limits.
His organisation would like to see the Ministry for the Environment put in place an effective pesticide reduction programme.
The FSA, though, says it's very confident in the chemical safety of foods grown and imported into New Zealand.