Pesticides in fruit and vegetables

Are they harmless — or is the truth that we don’t really know?
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  • Updated:10 Mar 2006

02.What are the risks?

If you’re a farmer, or you use pesticides in your garden, you’ll have seen some dire warnings on the labels. Pesticides can be distinctly nasty (some of them are based on chemical warfare agents developed during the Second World War), so it’s not surprising there’s a lot of published research on their toxicity.

  • Some experts say the research results show little or no risk,
  • others argue that pesticides are toxic even at very low levels.

The issue has become highly controversial. Passions are aroused on both sides — and it’s all too easy to selectively quote studies that support your point of view.

There’s another factor to take into account when trying to discuss pesticide use rationally: the ‘outrage effect’. Science isn’t everything when it comes to risk. To most of us (including scientists on their days off) how we rate risk also depends on various ‘outrage’ factors. For example, we’re more likely to be outraged by risks over which we have little choice or control. Skiing’s risky but fun because we choose to do it and believe we’re skilful enough to avoid accidents.

So even though in reality eating food contaminated by pesticide residues is no more risky than driving to the supermarket, we’re more concerned about the pesticides because most of us choose to go by car. And we’re exposed every day to natural toxins in foods that are a lot riskier than pesticides — potatoes, for example, can contain toxic alkaloids (especially if they’re a tad green), mushrooms contain hydrazines that can cause cancer and barbecued meat is another source of cancer-causing toxins. But these are familiar foods; we’re comfortable with the risks and there’s no outrage.

However, there are some real concerns

  • Scientific uncertainty. It’s important to remember that, while science delivers more or less reliable knowledge, there’s an element of uncertainty in all research findings. This is a particular concern in studies of pesticide toxicity because the levels allowed in foods are so small that harmful effects may not be immediately obvious. There can be a long time lag between exposure to a carcinogen, for example, and someone developing cancer (as was found with asbestos and cigarette smoke). So while the risks from pesticide residues now seem very low, there’s always the chance that pesticides currently believed to be safe may one day be revealed as hazardous. This was the case with DDT, which was once widely used as a pesticide and is now banned.
  • The cocktail effect. While most experts agree that the risk of cancer from individual pesticides is very low, others are concerned that exposure to a ‘cocktail’ of pesticides may increase the risk.

A report recently published in the UK by its Food Standards Agency upheld the scientific validity of these concerns and called for more research.


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