The Independent has learnt, however, that the final report by Department of Health officials has raised safety questions about the effect of the spray on asthma sufferers and pregnant women.
There is also concern that the natural chemicals in the spray may permanently damage nerve endings. Chief constables and rank-and-file members of the police service have been pushing for the introduction of the pepper sprays as a way of countering the growing number of violent and armed crimes.
Michael Howard, the Home Secretary, will shortly announce the results of the six-month study along with details of a new investigation to examine other potential side effects.
Nevertheless news that the pepper is not carcinogenic is a major breakthrough. It was the largest objection against the spray, which is already widely used by police officers in the United States and Australia.
The device uses the chemical oleoresin capsicum - which produces the heat and irritation found in peppers and chillis - and adds it to an aerosol. The chemical, when sprayed into a person's face, acts immediately blocking the victim's throat and eyes. Tests have shown that in just over nine out of ten cases the victim will be immobilised in seconds. People who are very drunk or who have taken drugs sometimes fail to react.
Although Department of Health scientists discovered no evidence to support the fear that the spray could cause cancer, their report is understood to highlight possible risk areas. As well as pregnant or asthmatic people, they are concerned that long-termexposure could affect a person's sensitivity to temperature and pain.
This possible dulling of the nerve endings would affect police officers, who would be handling the equipment regularly.
Chief constables are, however, expected to be pleased with the findings and to call for any further tests to be carried out as soon as possible. Having dismissed the option of more widescale use of firearms, they are looking for new ways to protect officers. New types of baton and truncheon have already been approved.
The measure is being considered at a time when police are having to face a growing number of violent people and armed criminals. As well as fears about the safety of the chemical, they will also have to overcome concern that the spray may abused in public order situations, such as demonstrations.