By Rebecca Morelle
Health reporter, BBC News
Leading toxicologists have warned green groups are "misleading" the public with chemical contamination campaigns.
The WWF wants dangerous chemicals phased out
They said they are deliberately and unfairly scaring the public.
In particular, they criticised a WWF campaign that has highlighted the presence of certain chemicals in blood, food and in babies' umbilical cords.
The scientists said the minute levels detected did not warrant the group's focus on health dangers, but WWF has denied it was scare-mongering.
The tests have formed part of WWF's campaign to strengthen proposed EU legislation, called REACH (Registration, Evaluation and Authorisation of Chemicals), on the testing and phasing out of chemicals.
They argue the presence of chemicals, such as musks (found in perfumes), brominated flame retardants, and dioxins (a by-product of heating processes), in the environment pose a danger to health in humans and wildlife, and more stringent protective measures are needed.
But while many scientists believe monitoring levels of chemicals and the phasing out of dangerous ones are vital, as is REACH, they say WWF and other green groups have been playing on the public's fears to highlight their campaigns.
Alistair Hay, professor of environmental toxicology from the University of Leeds, said: "The presence of these things is a warning that we are exposed to chemicals in the environment and we have to try and understand what this means - but it is wrong to frighten people."
While David Coggon, professor of occupational and environmental health from Southampton University, added: "The message they are putting across is misleading, and deliberately so."
According to Dr Andrew Smith, of the Medical Research Council Toxicology Unit, University of Leicester, it is the amount of a chemical present that is key when considering toxicity.
And the researchers said the levels of the chemicals found in some of the tests were extremely low - measured in parts per billion or parts per trillion.
Although some of the chemicals were dangerous at high doses, they said, one could not go on to assume that because a trace amount was detected it posed a danger.
Dr Smith said: "Any toxicologist will tell you that dose - the amount - is the important thing.
"I would rather we didn't find these chemicals present, but trying to ascribe toxicity to them is a different matter."
Professor Coggon agreed: "One of the most important things in toxicology is to look at how a person is exposed and how much of a substance they are exposed to.
The WWF tested for chemicals in food
"The fact that you can detect something at all does not imply a material risk to health."
The researchers said the chemicals were being found in trace amounts because of advances in detection techniques that could uncover substances at ever smaller concentrations.
The researchers admitted there was uncertainty surrounding the effects of some of the chemicals, but said just because it couldn't be confirmed something was 100% safe this did not mean it was 100% dangerous.
Professor Richard Sharpe, an expert in endocrine disrupters from the Medical Research Council Human Reproductive Sciences Unit, in Edinburgh, said: "By and large, I think people shouldn't be worried. Most chemicals will not do any great harm at these very low levels. You have to put this into perspective."
Dr John Emsley, a visiting professor at Manchester University, said the word "chemical" had become a synonym for "toxic", and that the public was growing increasingly fearful of contamination, something he called "chemiphobia".
"I think the public are afraid because it is all about the unseen danger - it is presented as something malevolent lurking below the surface. You don't know what it is and you don't know what it does. It is a risk they do not feel in control of."
Elizabeth Salter Green, director of the WWF's toxic campaign, said: "I think WWF's raison d'etre is to protect biodiversity. We feel that there are certain drivers such as chemicals undermining future generations' viability.
"We are keen that the core aim of REACH is maintained - to protect future generations of humans and wildlife while not undermining the competitiveness of the chemicals industry."
She said she was concerned with possible health risks associated the lifestyle exposure to different combinations of low-level chemicals, and pointed to studies which revealed the chemicals were working together.
"We are weighing up the difference between alarm and ignorance - we are not looking to scare-monger - we are looking to highlight an issue such that the UK population are aware of exposures and to call for better regulation."