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Tuesday, 24 April, 2001, 10:55 GMT 11:55 UK
Foot-and-mouth pyres: Dioxin danger?
Funeral pyres: Are they a health risk?
Residents of some of the areas hardest hit by foot-and-mouth disease have been forced to live for some weeks with the stench of burning animals.

Now there are fears about health risks from the blazing pyres as they release cancer-causing dioxins into the air.

The Department of Environment has confirmed that fires lit during the first six weeks of the foot-and-mouth crisis released 63 grams of dioxins into the atmosphere - 18% of the UK's average annual emissions.

The government insists the public health risk is minimal, but has nonetheless launched an investigation into the impact of the pyres on people living nearby.

So what are dioxins and what is already known about them?

What are dioxins?

Dioxins are a group of chemicals known to increase the likelihood of cancer.

An unwanted by-product, they are formed when heating processes create certain chemicals - chlorine is the best known.

Environmental campaign groups describe them as among the most dangerous toxins known.

The government says that a pyre's output is equivalent only to that produced by two bonfire nights.

But others point out that while this is the case, the pyres are concentrated in small areas rather than spread throughout the nation.

Precisely how much dioxin is being released, or where it will land, is still to be confirmed.

In this case, there are fears that dioxins, drifting through the air, could settle on soil or crops and somehow pass into the food chain.

Once there, they persist and gather in body tissues over the years.

Scientists are working to establish their exact toxicity, but a draft report from the US Environmental Protection Agency indicates dioxins are considered a serious threat to public health.

The World Health Organisation has classed one dioxin as a serious hazard to human health.

Where do they usually come from?

Waste incinerators and chemical and fertiliser manufacturing plants are more usual sources of dioxin emission.

However, elsewhere in the world, volcanoes and forest fires also produce significant amounts of dioxins.

What is a safe level of exposure?

In 1990 the WHO set a safe daily exposure level of 10 picogrammes per kilogram of body weight.

A picogram is one millionth of a millionth of a gram.

However, following further studies this was re-evaluated in 1998 to one to four picogram per day.

Health risk?

The first disease to be associated with dioxins was the extreme skin disease chloracne. It causes acne-like pustules to form across the body and can last for several years.

Most concerns now lie with the potential of dioxins to cause cancer, but they are also suspected of affecting reproductive health, lowering sperm counts, causing behavioural problems and increasing the incidence of diabetes.

There is a growing body of research indicating that dioxins can cause such diseases.

The key evidence about the effects of dioxins came from the population of the Italian town of Seveso, which was contaminated following a factory blast in the 1980s.

Scientists studied people who lived some distance from the plant but had not been evacuated.

Both sexes were more likely to have cancers of the blood system, while women were also more likely to have cancer of the gall bladder and liver system, the study found.

Also of concern is the effect dioxins can have on unborn children and infants, as they can be passed through the placenta or carried in breast milk.

How do they get into food?

In living organisms, toxins reside in fat. This means they can persist in the food chain through a process called bioaccumalution.

They are mainly found in meat and dairy produce, but are also found in poultry, fish and on unwashed fruit and vegetables.

Fish accumulate dioxins through exposure to water - dioxins are repelled by the water and attach themselves to the fatty fish

Unless feed becomes contaminated, as was the case in the recent Belgian scare, animals are usually exposed to dioxins settling on their food from the atmosphere.

They accumulate in the fatty tissue of animals and the longer that animal lives, the greater the build up.

Dioxins in the air also land on fruit and vegetables, but washing can get rid of these as they are not absorbed into the plant itself.






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