Finger pointing and farm chemicals

Ever since Rachel Carson's 'Silent Spring', a book about the environmental impact of DDT, there have been people ready to believe the worst about farm chemicals.

Whenever there is a mysterious cluster of cancer cases, deformities, dead fish or birds; the first finger is inevitably pointed at farm chemicals.

Any number of people who are capable of understanding statistics, correlation and causation are prone to emotional accusations, as well as demands that the chemicals be proved innocent. Even in the face of objective information showing the accusations are false, many remain convinced they know better.

This thinking bedevils the resolution of legitimate issues. Whether a cancer cluster has a local cause or is just another statistical spike is enormously important to those affected. Pursuing false causes based on prejudice and bigotry diverts attention away from finding real answers.

An international example of this is seen in relation to the collapse in honey bee colonies in various parts of the world.

The cause is not known, with suggestions ranging from Varroa mite to loss of habitat, air pollution, malnutrition and, of course, agricultural chemicals. In fact, accusations about agricultural chemicals have been repeated so frequently that many now believe it must be the truth.

The problem itself is genuinely serious. Were honey bees to disappear, the consequences for agriculture would be enormous. While we might miss the honey, bees serve a vital role in pollinating various fruit, vegetables and pasture plants.

Despite the obvious fact that bee colonies have not collapsed everywhere, including countries where the same chemicals are used (such as Australia), there has been a relentless campaign to find agricultural chemicals responsible. The effort and resources committed to this might have come up with the real answer by now if they had been used more rationally.

A domestic example is the two-headed fish saga near Noosa in Queensland, first reported in 2006. Armed with nothing more than their prejudices, a small group of people convinced a gullible media that a series of incidents at a fish hatchery involving deaths, deformities and other abnormal development had to be due to agricultural chemicals used by a neighbouring macadamia farm. Those who have only followed the issue superficially probably now believe it to be true.

The furore led to a Queensland government inquiry, which enlisted the assistance of highly qualified scientists, to determine whether the chemicals were guilty.

In short, the evidence did not support the accusations. Couched in the cautious language of science, the inquiry's final report says:

"Based on the available evidence, it is difficult to support the hypothesis that chemicals in the Noosa River are affecting fish in the river to the extent that their reproductive processes are significantly impaired, subsequently leading to failed reproduction in the hatchery. It is concluded that other factors including methods of collecting and handling fish, water temperatures or other factors are more likely to have caused the malformed embryos."

The report concedes more investigation would be required to exclude all possibilities that chemicals had any role in the nine incidents examined, but strongly suggests this would prove negative in the end.

Given the obsessive character of those who blame farm chemicals, there is a possibility that further studies may indeed occur. Since it is not actually possible to prove a negative, the faintest glimmer of doubt is enough to convince such people that they are right.

That would mean yet more diversion of resources away from determining the real cause, and the possibility that it might turn out to be correctable.

Ultimately, their aim of prohibiting the use of farm chemicals on the macadamia farm and other areas around the fish hatchery would deliver no benefit to the hatchery but inflict harm on the farmers.

This highlights the fact that anti-chemical obsessions are never harmless. There is a price to be paid for adopting an unduly precautionary approach based on prejudice rather than objective evidence.

Perhaps the most glaring illustration of this is the ban on DDT. While there were obviously solid grounds for limiting its widespread use as an outdoor spray, the ban meant it could not be used even when humanitarian benefits outweighed the environmental impact.

Literally millions of people in the developing world died from malaria because it could not be used to control mosquitoes. It took decades for common sense to return, and now more than 12 countries are using it again for indoor mosquito control.

Farm chemicals are safe when used as intended, in the right place and at the right rates. Without them our food would be vastly more expensive and of much lower quality. But some are also dangerous when misused.

One of the characteristics of rational, objective adults is an ability to distinguish between significant and trivial risks. When it comes to farm chemicals that is a qualification many seem to fail.