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Feature

Waste Space

By Tim Frederikson

Have you ever given any thought to the effects upon "Con the fruiterer" if somebody issued a national media statement that he, and other fruiterers, were retailing chemically contaminated produce? Have you ever given any thought to the emotions of people who bought the produce before the statement was issued? Or those who had, in good faith, imported it?

Can we blame the media for publishing statements issued in the "public interest" by persons who have failed to determine the accuracy of their allegations?

These questions arise in the wake of the recent uproar over the importation of bananas allegedly contaminated with aldicarb, a translocating systemic carbamate insecticide which is applied to the soil, taken up through the plant and then deactivates through leaf and root exit points.

Aldicarb is retailed around the world as Temik or Propomyl. Chemical buffs know it as 2-methyl-2-(methylthio) propionaldehyde O-(methylcarbamoyl) oxime. It is a very toxic material if managed improperly. Plants undergoing treatment, together with the soil in which they are planted, can contain significant residues of aldicarb for approximately six to eight weeks after treatment.

If one was hungry enough to eat a banana (green though it will be) within four weeks of an aldicarb treatment, then it would be highly likely that the you would suffer for it. Whether or not you would die depends on how much aldicarb was applied, how much banana was eaten, the time over which the eating took place and the interval between the application and the eating. However, it should be pointed out that you will be eating this banana in the vicinity of or in, the tree.

Bananas take many months to mature and the protection afforded to them through aldicarb is instituted very early in the growth cycle. This allows the maximum benefit to be gained and also lets chemical reduce in toxicity while the fruit is still attached to the tree. Parasites -- monkeys, insects, birds, poachers -- are deterred during the growth stage by the insecticide and the green nature of the immature banana.

When bananas are harvested and washed, a "de-ripening agent" is applied to the banana's skin to help it survive until it reaches the market. Where the banana is being exported, a fumigation with methyl bromide or similar compound is done after loading to kills hitchhikers and parasites such as spiders, snakes, beetles and rats.

While all this is going on, any residues from the aldicarb have long since been eliminated. When arriving in New Zealand, the shipment will be treated to ensure that no animal or insect life has accompanied the bananas. Twenty-four hours later, the shipment is ready for release to the importer.

This careful process relies upon international co-operation and established procedures, carried out by people familiar with the processes and the materials involved. If a country was exporting immature bananas which were found to contain excessive chemical residues, the shipment would be returned or condemned. This action would become known internationally within hours and the exporting country's produce impounded throughout its markets.

New Zealand has suffered this in the past. Our lamb and dairy product exports were subjected to DDT maximum residue limits (MRLs) on the US and European markets, our mushrooms have been caught with prochloraz and diazinon MRLs, and our treated timber was nailed with an MRL for sodium pentachlorophenate in Australia. The effects on our overseas trade was instantaneous and extremely serious. Whether these MRLs were introduced as a protectionist manoeuvre or were founded on scientific evidence could be debated at length. The important point to note is that it is not in any country's interests to have a residue detected and they therefore take extreme measures to see that their produce is acceptable.

So how come the banana warning was released? Did someone sell us "dud" fruit? The wording of the statement made it plain that bananas on sale were contaminated by aldicarb and were dangerous to eat.

Our Health Department reacted immediately by conducting tests and by requesting a DSIR analysis of random banana samples. They also asked that the organisation responsible for issuing the media statement produce the evidence for the allegations. Concurrently, 17 retailers commissioned an independant testing facility report to check 300 samples from Auckland, Wellington and Christchurch.

Within four days, the DSIR had cleared their bananas as being safe for human consumption with regard to aldicarb, and the Health Department released that information publicly. Two days later, the private testing facility had completed an analysis for all the chemicals used in the banana growing, storage, transport and sales activities and cleared them of contamination, although some chemicals were detected.

Seven days after the original warning, there was still no evidence produced to substantiate the claims of contamination. However, the organisation involved had made several other claims about the abilities of the DSIR, the independence of the testing facility and the nature of the testing carried out. The organisation pointed to information obtained from the US which outlined concerns over immature bananas from South America with detectable residues of aldicarb. However, the report in which this information was contained was dated 1989 and had no relationship to the shipments in question.

In the meantime, the sales of bananas had slumped by levels of up to 75%, and the value of the vital primary produce of the "banana republics" had dropped significantly.

Science to the rescue? Science reaching into the lives of all banana growers and eaters? Definitely! Good science, honest science. The sort of science that would have been better employed before the media statement was issued.

Tim Frederikson is a chemical safety consultant.