This week, two scientists called for curbs on the use of 200 chemicals - to protect very young children. They were accused of scaremongering, but anyone who dismisses worries about our toxic world, writes Sarah Boseley, should remember what happened to the Romans ...

The article below stated that some dish-washing liquids and detergents contain alkylphenol ethoxylates, which are thought to disrupt hormones. To clarify, in Europe they are no longer used in domestic products but are contained in some industrial detergents and pesticides. In the US they are in domestic products including many liquid detergents for clothes. Lead has been squarely blamed, in some scientific quarters, for the decline of the Roman Empire. Lead was the fabric of the cooking pots, the wine urns, the water pipes, and the plates in Roman times; it was used in makeup; it was even used for its sweet flavouring. It contaminated the food and drink and befuddled the brains of the wealthy ruling classes, the people who could most easily afford classy metalware and were therefore most exposed. Why was Caligula degenerate? Why was Julius Caesar apparently sub-fertile for all his sexual proclivity? (He had only one child.) Because of lead, the theory goes.

However far-fetched some of that may sound, the Romans were certainly aware that lead was toxic. The slaves who mined it had a short and miserable existence. In fact, nobody has thought lead harmless for more than 2,000 years. In the 1900s, the deaths of children who had chewed on slivers of lead paint peeling from an Australian veranda were well documented. Yet through most of the past century there were few controls over the use of lead in paint, petrol, ceramic glazes and other products.

Lead is no longer permitted in paint and petrol in the UK. Children do not die from lead poisoning any more in this country, but the consequences of the lead-happy 1960s and 70s are with us still, according to two doctors who work in environmental and community medicine in Denmark and New York, and who have just published an alarming review of the potential for damage of the chemicals we use in our everyday lives.

"Almost all children born in industrialised countries between 1960 and 1980 were exposed to substantial amounts of lead from petrol that could have reduced the number of children with far above-average intelligence (IQ scores above 130 points) by more than 50% and might likewise have increased the number with IQ scores below 70," they wrote in a journal this week.

And this was not a minority journal for environmentalists. This was in the Lancet - one of the four leading medical journals in the world.

Dr Philippe Grandjean, from the University of Southern Denmark, is surprised that anybody raises an eyebrow at the idea that you or I could be thicker because of petrol fumes. "The main discussion about lead is not whether there has been a drop in IQ," he says. "I think that is widely accepted. I have met a couple of industry consultants who wanted to doubt it, but I don't think any serious researcher or scientist does."

No, the issue today, in his view, is not what substantial quantities of lead have done to your brain and mine, but what very small doses in the environment continue to do - not so much to an adult, but to a foetus or a small baby, whose brain is still developing. Not just elsewhere in the world, but right here in the UK, where there are still low levels of lead in the environment (some from past pollution, "like a debt from the past", as Grandjean puts it, and some from modern electronics and new pollution).

The point that Grandjean and his co-author Philip Landrigan, from the Mount Sinai School of Medicine in New York, want to make is that we know very little about the damage we could be doing to our babies' brains when we expose ourselves and them to modern cleaning fluids, cosmetics, pesticides, glues, plastics and other modern necessities made with potentially hazardous chemicals.

And they believe that there may be already evidence of what these chemicals are doing to us. Neurodevelopmental disorders, for example, appear to be rising, they say, although they acknowledge this is controversial. Many doctors argue that we are simply better at diagnosing them. But certainly more cases of autism are being detected than before. And it is the same with attention deficit disorder, Grandjean and his colleague add. Cerebral palsy is now common.

Are chemicals really causing these things? "I think so, but we don't know," says Grandjean. "In this whole group of disorders ... the National Academy of Sciences says 3% can be explained by known chemicals, 25% is probably environmental exposures of some kind and probably a genetic predisposition. Of the rest, a lot are unknown and some are inherited.

"We know with methylmercury, PCBs, arsenic and toluene that they can affect cognitive development so kids perform more poorly than they might have. Some are pushed over the edge ... but some are simply not doing so well in school. It definitely constitutes a problem for the kid and the family, but there are also consequences for economic production and social costs."

If all this sounds like scaremongering, it should be remembered that while only a handful of chemicals are now branded dangerous to neurodevelopment, a very long time was allowed to pass between people first becoming suspicious of them, and someone else imposing controls upon their use.

Lead is the most stunning example of our complacency. Arsenic is another. Powdered milk contaminated with arsenic in 1955 led to more than 12,000 cases of poisoning and 131 deaths in Japan. Among survivors, there was a tenfold increase in the proportion who were mentally retarded. But regulations on the control of arsenic still do not emphasise the need for protection of the developing brain. It is the same story with the few other chemicals for which there is real evidence of harm to the growing brain, such as methylmercury (an organic mercury compound), polychlorinated biphenyls (PCBs), solvents - including alcohol - and pesticides.

In this week's paper, Grandjean and Landrigan have pulled together a list of 200 chemicals in everyday use for which there is evidence of neurotoxicity although the case would not yet stand up in court. They argue that we should not wait for the final proof. It might take 20 years or 50 years to work out what the long-term consequences of exposure to some of these chemicals will be. We should act now, they argue, and put in strict controls for their use to protect babies. If it turns out that the chemicals are harmless after all, then the controls can be lifted, they say. Better safe than sorry.

The Lancet review is deliberately timed. The European Council of Ministers will next month consider new legislation, known as Reach, which could toughen controls over industrial chemicals. For the most part, the chemicals under consideration are those known to be cancer-causing, damaging to the immune system or hormone-disrupting. (Those that could possibly damage children's brains are not even up for discussion at this point.)

And even though the list of hazardous chemicals on Reach is limited - probably 1,000 out of some 30,000 currently in use - the environmental health lobby is concerned that ministers may draw back from the main proposal - which is that where there is a safer chemical, one with known hazards should not be used.

Colin Butfield, head of campaigns at the World Wildlife Fund, says there has been massive lobbying from the chemical industry. The official UK position at the moment, he says, is against. WWF ran its own tests on some 400 people, 300 of whom were in the UK, to find out just how polluted with everyday chemicals we all are. Many people had a cocktail of industrial chemicals in their bloodstream. "The levels were quite low - they were in parts per billion," he says. But while that might be fine, even if it is an uncomfortable idea for adults, many - but not all - scientists would say it is not fine for a foetus.

"There is a big scientific argument going on about it, but we are saying, why are you taking the chance?" says Butfield.

Some years back most of the medical establishment was silent about the possible hazards of chemicals in the environment because of a lack of evidence of real harm. But that is no longer the case. Today, at Unesco in Paris, a European network representing 2 million doctors, and including the British Medical Association, will demand that the Reach legislation is passed.

The doctors, together with scientists and environmental lobbyists, are meeting to promote the "Paris appeal" - 166 recommendations for improving environmental health. These include a ban on formaldehyde glue, a ban on the use of a chemical called DEHP (one of the phthalates) in medical plastics, and a ban on phthalates generally, as well as aldehydes and glycol ethers in cosmetic products.

Genon Jensen, director of the Health and Environment Alliance, which is convening the meeting, says many of the scientists speaking will, like Grandjean and Landrigan, be warning of the dangers of low doses of chemicals.

'We're not talking about the impacts you can see right now but what you may see in 20 or 30 years' time," she says. For example, "There is evidence from animal studies that shows that bisphenol A can affect genes, one of which may be implicated in obesity. Bisphenol A is used in the lining of canned food tins.

"The argument is always that the levels are so low that it is not doing us any harm because we are not sick or dying, but maybe in 20 years we will have Parkinson's or maybe I'm passing it to my child who may have birth defects," she says.

Another speaker will tell the meeting how Sweden cut its use of pesticides and saw a decrease in cancers known as lymphomas. There will be a presentation on the increased rate of birth defects among women in the first trimester of pregnancy working in fields where there is high pesticide use. Several studies have pointed to this, says Jensen. "The argument is what is the appropriate political and precautionary public health response."

The impact of chemicals on our everyday lives will continue to be a hugely controversial field until there is incontrovertible evidence of harm. This week, there have been sceptical voices over the Lancet review. Alan Boobis, a professor in experimental medicine and toxicology at Imperial College London, thinks that some of the evidence lacked rigour. "This is a risk-management issue. In implementing the precautionary principle it is important to take into account all relevant information and not just the potential harm that might result from inaction. For example, what would the consequence (health, economic, societal) be if some of the compounds on the list were banned or severely restricted on the basis of the precautionary principle?"

And the chemical industry will continue to lobby as hard as the environmentalists. It has a lot to lose. Grandjean says (sounding upbeat) he has already had his first threatening letter, but will not be deterred. "I am a physician," he says. "I have to speak on behalf of human beings, not on behalf of money-making".

Safety first - how to minimise your exposure to chemicals

Hazardous chemicals are everywhere, from the bedding and clothes we use, to the food we eat, the air we breathe and the cars we buy. It is impossible to create a totally safe haven, but you can minimise your exposure.

Cleaning Most dish-washing liquids and detergents are made from petroleum; some contain alkylphenol ethoxylates, which are suspected hormone disruptors. If in doubt, buy natural products (such as Ecover), wash your hands with plain soap, and clean your windows with vinegar or lemon juice.

Children Avoid most plastic feeding bottles, which can contain bisphenol A, a hormone-disrupting chemical. Don't use old dummies and PVC toys that may contain now-banned phthalates. If pregnant, avoid paint or using DIY products that emit fumes. Buy children's clothes and pyjamas without plastic logos or chemical treatments.

Air fresheners Aerosol propellants contain flammable and nerve-damaging ingredients as well as tiny particles that can lodge in your lungs. Fragrances of all kinds can provoke allergic and asthmatic reactions. The solution? If the room smells, open a window.

Mites Companies recommend you eradicate them with sprays, gels, powders and liquids, but most have very active chemical nasties. The solution is to ventilate rooms, air your beds, vacuum all surfaces and mattresses, and wash fabrics at high temperatures.

Living rooms Carpets and flooring materials may be treated with a wide array of chemicals that some people are allergic to. Use natural flooring such as cork tiles, or cotton rugs that can be washed at high temperatures.

DIY and gardens Avoid painting, paint stripping or using DIY products unless using eco-friendly brands. Don't occupy newly painted rooms, and avoid using pesticides indoors or in the garden. Use water-based varnishes and glues, paints, stain removers, sealants and adhesives; and buy paints made from plant oils.

Cars That "new car smell" comes from the high levels of chemicals escaping from the plastic, upholstery, carpeting and other synthetic materials. Beware!

Food Don't let food come into contact with PVC clingfilm. Buy organic fruit and vegetables. Wash and peel food.

John Vidal

· For more information, go to safershopping.wwf.org.uk or greenpeace.org.uk/products/toxics/