Vegetable growers using banned chemical

Cucumbers and bok choy were among the locally produced crops tested for excessive chemical use. Photo / NZ Herald

Residue of a banned chemical acutely toxic to humans at high levels has been found in cucumbers and bok choy.

The New Zealand Food Safety Authority looked at locally produced and imported crops which were prone to exceeding chemical limits, and found nine cucumber samples and one bok choy sample contained traces of endosulfan which was banned by the Environmental Risk Management Authority in January last year.

The chemical is outlawed in 62 countries, and was banned in New Zealand after Erma decided the level of harm of continued use of it exceeded any benefits of its continued use.

Erma says the chemical is "acutely toxic to humans at high levels".

Of the 10 results which tested positive, none was a safety concern and the two highest readings were between 50 and 60 parts per billion, NZFSA adviser Paul Dansted said yesterday.

But the positive results could suggest growers were still using the banned chemical, he said.

"The fact that we found the residues at all seem to indicate something is going on, and particularly the higher findings suggest the chemical might have been used after the ERMA prohibition."

He said investigators were following up on the detections, and if growers were found to have used the banned chemical they faced being audited at their own cost.

The study by the Food Residue Surveillance Programme also found concerning levels of other chemical residues in bok choy.

Ten of 23 samples contained levels of the fungicide chlorothalonil or the insecticide thiamethoxam over the allowable limit.

Dr Dansted said that although the levels of chemicals found in bok choy were not a safety risk they were still a concern.

"Although our safety assessments show that an average-sized adult weighing 70kg could eat 1.7 kilos a day of the bok choy with the highest residue for the whole of their life with no effect, this level of non-compliance is concerning," he said.

Chemical standards were breached because growers were confused over how to classify bok choy.

Many had considered bok choy as brassicas instead of leafy vegetables, which have a much lower limit.

"This understandable confusion has led to fairly widespread non-compliance," Dr Dansted said.

The authority was working with Horticulture NZ to inform growers of the correct use of agricultural chemicals on bok choy.

Samples for other crops contained above-limit levels of the insecticides methamidophos and thiacloprid in four samples of locally grown cucumbers, and two samples of imported oranges contained too much of the fungicide imazalil.

- NZPA