Thirty years ago, 2001: A Space Odyssey promised a future in which Hal, a frighteningly omniscient computer, killed people in the name of security and the national interest. Well, here we are, and the reality is a little different. If you ever wonder about the possible dangers of modern technology, you're probably thinking about your mobile phone. Is it going to fry your brain? Will anyone notice if it does? While electromagnetic fields (EMF) are linked to many of the health threats that 21st century technologies pose, they are not the only problems. We also have to contend with chemical contaminants, computer-related fungi, and even desk rage.

There have been conflicting reports about the health risks associated with mobile phone radiation and other EMFs. But last year's parliamentary select committee report on mobiles did recommend the avoidance of excessive exposure, and suggested that children shouldn't be allowed to use them. Although the jury is still out, some are taking no chances. Expectant mothers in parts of China, Japan and South Korea are buying clothes that manufacturers claim will protect their unborn children from exposure. It's useful business too. Last year, one Shanghai outlet sold more than £300,000 worth of these garments.

If this seems extreme to you, consider Joan Stock of Bristol. She is so allergic to the EMFs generated by computer-controlled equipment that she has to live in a computer-free world, watching an old black and white TV and being driven around in a 15-year old car. When she is near the wrong kind of electrical goods she suffers piercing head pains, blurred vision and nausea.

While the effects of EMFs are subject to ongoing research and debate, there is less uncertainty about some of the other health problems associated with our increased use of technology.

When it's time to get rid of an old PC, your main concern is most likely to be security. But if you value your health you should be just as concerned about how it's disposed of.

Waste from electrical and electronic equipment (WEEE) is increasing rapidly. The UK alone annually discards more than a million tons of it, of which almost half is computers and IT equipment. Unfortunately, some of the toxins used in its manufacture have seeped into the food chain.

Take polybrominated diphenyl ethers, which are flame retardants that are widely used in computers and television sets. PBDEs have found their way into meat, fish, office air and human blood. A Swedish study found a 50-fold increase in PBDEs in women's breast milk between 1972 and 1997. PBDEs increase the risk of cancer, Liver damage and immune system dysfunction, if ingested. In children, they can hinder neurodevelopment, learning and memory.

'We need to set clear rules about what is required for environmentally-sound waste treatment,' says Margot Wallström , European commissioner for the environment. Hence the recently agreed draft electroscrap law for managing WEEE and restricting hazardous substances in product manufacture. The European Commission is proposing to ban PBDEs, and some other hazardous substances used in product manufacture, from 1 July 2003. Industry will have until January 2006 to comply, and find substitutes for 32 groups of substances, including lead, cadmium, and hexavalent chromium.

According to Dr A Michael Warhurst of Friends of the Earth, this is too little, too late. He claims that the European Commission has capitulated to chemical industry lobbying: 'The new strategy will not ban the hundreds of chemicals that are contaminating our bodies, nor will it force industry to use the safest chemicals.' Even so, by 2003 we should see producers of electrical and electronic equipment taking responsibility for removing and recycling waste. Some, such as Hewlett-Packard and IBM, have already initiated recycling projects.

But the health problems associated with our increased use of technology extend right into the heart of the healthcare system. Following the installation of computers, US researchers have found aspergilllus fumigatus in the intensive-care wards. It's the second most common human fungal pathogen after candida albicans, and a major cause of death among immunocompromised patients. According to Dr Gregory Forstall of the McLaren regional medical centre in Michigan, analysis of the dust found on central processor units and the grids on cooling fans revealed several types of yeast and some 'filamentous mould', including five types of fungus capable of making you ill. The risk of contamination means hospitals will need to go to some lengths to ensure their computers are clean. It will not be that much of a problem in the UK, where there are fewer hospital computers, but in some US hospitals, each intensive care bed has a PC and monitor.

If that isn't enough to make you fume, the PC on your desk apparently is. When 4,200 British computer users were recently quizzed about their relationship with technology, 1,050 admitted to beating their computer - behaviour frequently brought on by 'annoying' emails. Rocketing stress levels can lead to some very unpleasant incidents. Witness the US software engineer who last year killed seven of his coworkers. Even Hal wouldn't have approved.