COT deaths are not caused by a fireproofing chemical found in babies' mattresses, according to a Government report.

Research by its Expert Group on Cot Death Theories concludes that there is no evidence that the chemicals, found in PVC mattresses, produce toxic fumes which can be fatal to babies.

Sir Kenneth Calman, Chief Medical Officer, set up the group of 12, led by Lady Limerick, in 1994 after the theory was highlighted by TV detective Roger Cook. The research since is estimated to have cost the Department of Health #500,000.

Lady Limerick said: ''Our main conclusion is that there is no evidence to suggest that antimony or phosphorus containing compounds used as fire retardants in PVC and other cot mattress materials are a cause of Sudden Infant Death Syndrome.

''Parents can be reassured that the toxic gas hypothesis and the claims put forward on the Cook Report do not stand up to scientific scrutiny. We have been thorough in our research and have found no link between cot deaths and chemicals added to PVC cot mattresses.''

Sir Kenneth dismissed claims that the research was a waste of money and said he believed the study was worthwhile.

He said: ''The issue is that here was an important potential problem and we believed we must do everything we could to make sure there was nothing we could do to prevent it.

''I think any work which could save the lives of children in a group of diseases we do not know much about must be worth doing.''

The Cook Report in November 1994 claimed that the primary cause of cot death was poisoning by gaseous phosphine, arsine, and stibine. These were said to be generated by the fungus scopulariopsis brevicaulis from phosphorus, arsenic, and antimony compounds in fire retardant or plasticiser in the PVC.

Sir Kenneth said there were six key messages to parents as a result of the research. The advice is contained in the leaflet Reduce the Risks of Cot Deaths and includes:

qplace baby on his/her back to sleep;

qcut smoking in pregnancy;

qdo not let anyone smoke in the same room as your baby;

qdo not let the baby get too hot;

qkeep the baby's head uncovered;

qif baby is unwell seek advice promptly.

An interim report published in 1995 showed there was no evidence to support the chemicals theory. Research into 148 young babies at Great Ormond Street Hospital in London published last year also rejected the theory.

Sir Kenneth said: ''Sudden Infant Death Syndrome is a matter of considerable public concern and the Department of Health puts high priority on investigating its causes and reducing the numbers.''

Conclusions reached were based on the following:

qcot mattress contamination with the fungus scopulariopsis brevicaulis is rare and no more common in mattresses used at the time of a cot death than in other used mattresses;

qthere is no evidence for the generation of gases from phosphorus, arsenic, and antimony from cot mattresses by the fungus when tested using conditions relevant to an infant's cot;

qthere is no evidence of poisoning by phosphine, arsine, or stibine in infants who have died;

qlow amounts of antimony can be detected in samples from the majority of live infants, and, even newborn infants, the concentrations in tissues of SIDS infants were not different from those in infants dying from known causes;

qthere is no evidence that the changing rates of SIDS deaths correspond to the introduction and removal of antimony and phosphorous containing fire retardants in cot mattresses.

Ten babies still die every week from cot deaths.