By TOM KELLY

Last updated at 22:00 08 January 2007

Cremation costs are set to rise by up to £100 - because the teeth of the dead are poisoning the living.

Bereaved families are to be hit with a charge to fund new filters that stop toxic fumes from vaporised mercury fillings polluting the atmosphere.

The levy could see the price of having a loved one cremated rise by up to a third.

But environmentalists say it is vital to cut the spiralling mercury emissions from dental fillings that contaminate the air, waterways, soil, wildlife and food.

Mercury pollution has been linked with birth defects, kidney disease and multiple sclerosis.

Cremations already cause nearly one sixth of all UK emissions of the metal.

Left unchecked, this would likely rise by two thirds by 2020, making crematoria the biggest single cause of mercury pollution in the country.

In an attempt to stop it getting out of control, the government has ordered half of crematoria to fit the new filters by 2012.

Those who have already installed the new technology started charging an £35 for cremations this month.

And with the filters costing up to £300,000 to fit, there are fears the charge could rapidly rise to £100.

By 2013 all cremations will be subject to the new levy. Grieving relatives will be expected to pay, regardless of whether their loved one has any mercury fillings.

Duncan McCallum, secretary of the Federation of British Cremation Authorities, said: "The government's decision was that the person at the end of the chain pays, and unfortunately that is the family of the deceased.

"We would have preferred some funding to assist the installation."

He said the charge would be reviewed annually, and it was impossible to predict how high it could rise.

Cremations now account for around three out of four funerals in Britain. Most cost between £300 and £400, but the average cost of the full funeral is £1215.

The rise in mercury pollution from crematoria is caused by increasing deaths in what dentists describe as the "heavy metal generation" - those in their 40s and above.

These people are dying with more teeth because of better dental care.

But many of those teeth are loaded with potentially dangerous levels of mercury-laced fillings.

Millions of Britons have two to four grams of mercury in their mouths.

Just a single gramme in a 25-acre lake can raise toxic levels in fish to danger levels.

Adults who have absorbed mercury or inhaled mercury vapour lose their appetite, are emotionally unstable, have trouble sleeping and develop gastric problems, sore gums and dribble excessively.

Researchers have also found that higher levels of mercury can lead to an increased risk of heart disease in men.

High mercury levels in food are especially dangerous for pregnant women, affecting their baby's central nervous system.

Other countries including Austria, Belgium, Germany, Holland, Norway, Sweden and Switzerland have already taken steps to regulate mercury emissions from crematoria.

The only alternative way of cutting mercury emissions from dental fillings would be to remove filled teeth from bodies before cremation, but experts say this would be too time consuming.