Can kettles kill? The question, as surreal as it might sound, is worth answering if supporting evidence exists. Likewise, the equally alarming prospect that crop spraying, hairdryers, electricity pylons, power substations and mobile phones might, unbeknown to many of us, cause early death.

Such concerns have become a staple diet of government bodies lately as public health has sped its way up the agenda. The driving force is a concept known as the Precautionary Principle, a better-safe-than-sorry stance dictating that risks should be minimised even before hard evidence emerges.

So it was that an official from the Health Protection Agency (HPA) issued a heart- quickening warning last week about electric kettles, hairdryers and other household appliances. There are unanswered questions, she said, about the health effects of electromagnetic fields around such equipment which, until known, should demand advice to limit possible dangerous exposure.

That the HPA report itself, an investigation into electrosensitivity, found no evidence of a proven scientific link between electromagnetic fields and suggested symptoms such as rashes, headaches and fatigue was not sufficient to silence the doubters. When the official was pushed to explain the report’s message, a familiar theme emerged: in a world governed by precaution, anything can carry an ill-effect until proven otherwise.

The media, somewhat surprsingly, treated the suggestion that the public should do “practical things to reduce exposure, such as staying away from appliances and not buying cheap, tinny hairdryers”, with commendable restraint.

While the trend for tub-thumping scares is not new, it is growing rapidly and at a time when measured assessments of threats to public health are needed as never before. In September a report from the Royal Commission on Environmental Pollution gave warning that “it is not implausible that there may be a link between pesticide spraying and chronic ill-health”, though no cases could be confirmed. It went on to recommend compulsory 5m “buffer zones” on farms, which campaigners against crop spraying took as vindication of their claims.

The National Radiological Protection Board sparked lurid headlines earlier in the year over the safety of mobile phones. Sir William Stewart, its chairman, said that if there was a health risk — which remained unproven — it would be greater for the young. This prompted Rosie Winterton, the public health minister, to warn parents to be “very careful” about the time spent by their children using mobiles.

These problematic reports appear to have two sources: self-justification on the part of researchers who want grants renewed and the determined desire of scientists not to miss a health horror on their watch. The latter motivation — borne of sorry sagas such as mad cow disease, asbestosis and the miners’ affliction pneumoconiosis — is commendable. But it is worth remembering that while there are possibly unpleasant and unknown health risks at large, a little knowledge can be an even more dangerous thing.

Sam Lister is the Times health correspondent

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