When Sharna Richardson and her playmates stumbled upon a mass of ants near her home, they decided to fetch some ant killer.

After excitedly sprinkling liberal doses of the Doff white powder over the insects, they carried on playing until dusk.

But within hours, Sharna, a fit and healthy child with no diagnosed allergies, became violently sick after licking some of the powder from her hand.

Realising what she had done, her frantic mother Angela gave her four glasses of water in a futile bid to cleanse her system.

Mrs Richardson, of Bulverhythe Road, St Leonards, said: "I knew something was seriously wrong as she projected the water straight away.

"She was complaining that her head hurt and she looked so pale. That's when I said to my husband, 'Lee, I don't like this'."

As Sharna's head pounded, Mrs Richardson called the family doctor who ordered she should go to the Conquest Hospital in Hastings straight away.

From there Sharna, a pupil at West St Leonards Primary School, was transferred to Guy's Children's Hospital in London. She died the next day.

Her death has been linked to the chemical lindane, a widely-sold pesticide used in agriculture, timber treatment and as a domestic pest control, like ant killer.

A post mortem examination carried out in January by Dr Iain West, a consultant forensic pathologist at Guy's, concluded that lindane had been a factor in Sharna's death.

Experts had believed that lindane could be lethal if a third of a bottle was consumed by a child of Sharna's weight, based on toxicological data from the World Health Organisation.

But at Sharna's inquest in Hastings, it emerged she had ingested less than a teaspoonful.

Lindane has also been linked with breast cancer, birth defects and problems with the hormone system, prompting it to be banned in many countries.

All this has led to a Ban Lindane Campaign, organised by an alliance of groups including Friends of the Earth and public service union Unison, which calls for the chemical to be immediately outlawed in Britain.

Nottingham-based pesticide manufacturer Doff Portland stopped using lindane in its products last June, ten months after Sharna's death in August 2000.

Following an EU decision in July 2000, there will be a statutory withdrawal of lindane products from June.

But it means it is still legally on sale until then and the Ban Lindane Campaign has called for all existing stocks to be safely disposed of, with pesticide manufacturers bearing the cost.

The crusade is being backed by Mrs Richardson, 37, a cleaner, who believes her daughter would still be alive today had the product been taken off shelves earlier.

She said: "Lindane is kept in thousands of garden sheds and kitchens up and down the country yet many people probably don't realise how dangerous it is.

"Only now our daughter has died have we been able to find out how dangerous it really is. It's a warning to other parents. I would hate for any other parent to have to go through what we did."

David Buffin, of the Ban Lindane Campaign, said lindane was a pesticide developed in the Forties when far less attention was paid to detailed experimentation to prove a chemical was safe.

He added that without an awareness-raising campaign, it was likely products containing lindane would remain in people's garden sheds and homes for years after the ban comes into effect in June.

Sandra Bell, of Friends of the Earth, said: "Lindane is a dangerous chemical which should never have been allowed on the shelves of DIY stores.

"Sharna's death shows that the existing regulations for pesticides do not offer enough protection.

"The Government must look again at the way it approves pesticides. It must build in a much more cautious approach, including higher safety factors, to account for children or adults who may be very sensitive to particular chemicals.

"Where reliable data is not available, as was the case with lindane, the Government should be prepared to ban pesticides."

Murray Smedley, technical manager at Doff Portland, said Sharna's death had baffled experts, including himself.

He said: "It's a tragic case but one which, to our knowledge, has not happened before."

Meanwhile, Mrs Richardson, who has two sons, makes a weekly vigil to Sharna's grave at Hastings Cemetery, where she lays beside her husband's parents.

She said she still tortured herself with questions about why her fit, healthy and beautiful young daughter could die in such a way.

She said: "It's a tragedy beyond words. I've not just lost a daughter but also grandchildren and even great-grandchildren, all because of lindane. It's a waste of a life."