Insecticide residues up to five times higher than legally allowed have been found in some produce.
The Food Safety Authority's annual surveillance programme tests for chemical residues in fresh, unwashed produce, and this year looked at spinach, celery, garlic and ginger.
In one sample of spinach, the insecticide ethamidophos, which has a maximum residue limit of 0.5 milligrams a kilo, was recorded at 2.6 mg/kg.
Another insecticide, cyhalothrin, which has a limit of 0.1mg/kg, was recorded up to 0.2 mg/kg.
In one celery sample, the insecticide acephate was recorded at four times over the residue limit of 0.1 mg/kg.
Overall, six out of 48 samples showed residues above the permitted level, though the authority says the residue levels did not pose a risk to human health.
The authority's principal advisor for chemicals, Paul Danstead, says the breaches indicate a only few growers are not taking enough care.
For example, he says, the residue problem in spinnach related to only two growers. The authority says it will be holding discussions with growers.