They are the tiny and potentially lethal guests that have taken up permanent residence inside the body of almost every adult Briton.

A toxic cocktail of 27 chemicals is circulating in the bloodstream of the average person, a disturbing new scientific study has proved.

The by-products of modern living - including PCBs, pesticides and even flame retardants required by law - are endlessly circulating in the bloodstream, where they are suspected of triggering a number of diseases including cancer.

One of the most worrying aspects of the research is that some of the contaminants lurking inside our bodies were banned by law more than 30 years ago.

Scientists tested more than 150 volunteers aged between 22 and 80 for traces of 77 chemicals that pollute the environment. Volunteers included Holyrood MSPs Sarah Boyack and Christine Grahame, as well as one leading European politician.

The survey found the people they studied had between nine and 49 of the substances - routinely sprayed on crops, added to products such as paints, and used to protect furniture against fire - in their bodies.

None had a bloodstream totally clear of contaminants and the average figure for the number of pollutants was 27. Readings for locations in central Scotland were similar to those for the rest of the test sites, which included London, Cardiff and Belfast.

Dr Gareth Thomas, who analysed the results at the department of environmental sciences at the University of Lancaster, said: "In each of these groups there are chemicals that might produce a higher rate of cancer. There is also a multiplier effect that derives from being exposed to a number of chemicals."

Unborn and newborn babies were also vulnerable, Thomas said. "Children are most at risk from this shower of chemicals when they are either gestating or when drinking their mothers' milk. One solution will be to limit everyone's future exposure and come up with safer alternatives."

The chemicals tested fell into three main groups in widespread use over the past 50 years. Many were first made when manufacturers had no legal requirement to carry out safety tests but which have subsequently been linked to several cancers, reproductive disorders, a decline in fertility rates, birth defects and respiratory conditions such as asthma.

PCBs were used as paint additives and as insulators in the electricity industry and although they were banned in 1970 are still present in water and soil from which they make their way into the food chain.

The pesticides included known hazards such as DDT. The flame retardants, known as PDBEs, have been used extensively in textiles and plastics and in polyurethane foam for furniture and upholstery to reduce fire risk. Tiny pieces can flake off and be inhaled.

One of the Scottish volunteers had the highest recorded level in the country of one type of PCB.

The tests were commissioned by the international environmental campaigning group, WWF, to coincide with attempts by the chemicals industry to fight a tough new testing regime for its products being introduced across Europe.

WWF, which will publish the results this week, said they provided hard evidence of the levels of past exposure to chemicals across the country. "The industry may say the levels found were safe but the reality is that no one knows for sure," a spokesman said. "You can have a lag of 20 to 30 years - even longer - before you begin to see certain effects."

He added: "We want the industry to take this issue seriously and limit exposures for future generations."

Boyack, the former Scottish Executive environment minister, who has spent her life living in urban areas, including Edinburgh, Glasgow, London and Stirling, said she had agreed to be tested because there were "major public health issues involved".

She had 26 different PCBs, seven flame retardants and four pesticides in her blood - 37 chemicals in all. Levels of some PCBs and pesticides were well above average.

"These tests bring chemical contamination down to a human level," said 42-year-old Boyack. "I was curious to know what my exposure has been. It's a snapshot of my life so far but what I don't know is what will accumulate over the next 20 years or at what point it becomes a danger to my health. It all points to the need for a better testing regime."

Simon Pepper, head of WWF Scotland, who has spent the past 25 years living in rural Perthshire, said his test revealed "worryingly high" levels of some PCBs and pesticides.

His body contains 38 of the 77 chemicals tested for - well above the average figure. "I am alarmed because basically it means I am a walking toxic dump," said Pepper, 56.

"I was not high in flame retardants but many of the younger people who were tested were. Itís probably because I havenít bought any new furniture recently."

Another volunteer was Margot Wallstrom, the Swedish EC Commissioner for the Environment, who had 28 different chemicals in her blood, including traces of all three groups.

Wallstrom is in charge of piloting through new registration, evaluation and authorisation of chemicals (Reach) legislation throughout the EU. The aim is to gather crucial safety information on up to 30,000 potentially hazardous chemicals circulating in an array of everyday consumer products and subject them to a stricter testing regime.

Environmental groups say the original proposals have already been seriously weakened because of opposition from the chemical industry, which claims the new regime will force up costs and lead to widespread job losses.

"Reach could bring worldwide benefits for human health and the environment. But it looks as if the European Commission is giving too many concessions to industry," said a WWF spokesman.

The Chemicals Industry Association, which represents the industry, said it did not want to comment on the survey results until they were published.

On the Reach proposals, a spokesman said: "We are a heavily regulated industry already and we want to make sure that we have regulations that work."

- jwatson [at] scotlandonsunday [dot] com

2003 Scotsman.com