The seven confirmed deaths among heroin-users this week has brought the habits of over 13,000 addicts in Dublin into sharp focus. Tony Geoghegan of the Merchants Quay Project said the deaths were unprecedented, and this is because there has never been a situation where such a high number of heroin users died from what is still being called a "severe unidentified illness".

Not much is known about most of the seven people who died, all of whom were men. Gardai have said they were admitted to hospital with abscesses on their arms, legs and buttocks. They may have injected heroin into muscle or tissue, where veins have receded, and this could have caused a swelling and infection. The Eastern Regional Health Authority, however, has not ruled out the possibility of contaminated heroin.

While it had been thought that two women also died from the heroin-related illness, confirmation from the health authority that all the cases involved men has ruled Rosie Lakes and Maureen Gleeson out of this investigation. Gardai have not discounted the possibility that Rosie Lakes may have been targeted for providing information about the murder of prostitute Sinead Kelly in July 1998.

The deaths were more disturbing after a link was established to 12 similar deaths in Glasgow. Andrew Horne, a Dubliner who works as area manager at Turning Point, Scotland's largest drug centre, said the deceased had shown similar signs to the Irish deaths, with abscesses on the bodies. As eight of the 12 users who died were women, whose veins recede more quickly than men, the link with injections into tissue or muscle is a possibility.

Users in Glasgow have also been reporting unusually strong heroin recently, according to the Glasgow health board. Such heroin has required large amounts of citric acid to dissolve it. The combination of heroin and large amounts of citric acid is another possible explanation.

And there have been media reports in Glasgow of a more sinister nature. The Big Issue in Scotland reported last week that a former chemist may have deliberately put a contaminated batch of heroin into circulation.

Gardai say the only other known deaths of heroin addicts linked to contaminated drugs occurred two years ago when strychnine was found to have been mixed with the drug. Two people died as a result.

But the drug also claims lives in less dramatic ways. Earlier this month, the City Coroner, Dr Brian Farrell, said the use of heroin had reached epidemic proportions after he heard six inquests involving its use. No Government department or health authority keeps information on the number of people who die from heroin use but the 1998 national figure for deaths from drug dependence was 90.

People involved in drugs projects say the situation has not improved over recent years but they could not say whether there was a new heroin epidemic.

Gardai in the National Drugs Unit say there is possibly a new type of user on the streets today following the popularity of ecstasy about three years ago. "Party packs" were used by some people at raves, which consisted of an ecstasy tablet to get high and heroin the next day for coming down. Gardai say some people may have become addicted to heroin from this combination.

Often, heroin addicts do not need a specific means of getting caught up in the drug, however, as peer pressure often plays a part. John Gallagher, Labour councillor in Dublin and chairperson of the South Inner City Drugs Task Force, says a group of girls in a school recently said they wanted to be junkies when they grew up. "That was the way they were living. There is not enough thought put into education and prevention," he said.

Supply is also a problem as there is a tendency to move heroin from area to area to avoid police surveillance. Gardai say St Michael's Estate and Dolphin's Barn were previously the main areas for supply but now Thomas Street, Meath Street and Ballyfermot are performing that role.

Of the more than 13,000 estimated heroin users in Dublin, over 4,200 are receiving methadone treatment. More than 400 people are on waiting lists for such treatment. Services for addicts and their families have improved over recent years with the setting up of 13 local drugs task forces in Dublin, which offer a co-ordinated response to the drugs problem, involving gardai, health boards, probation services and community groups. Yet while good community relations have been established through these and other bodies, heroin continues to devour neighbourhoods.

For the 9,000 people who are not on treatment to come off heroin and who perhaps do not want help, Tony Geoghegan favours providing more needle exchanges, the option of injecting methadone and even making heroin available. "The present range of services don't attract all types of hard-to-reach heroin users . . if you want to attract heroin-users into treatment you need to make the treatment attractive," he said.

Vincent Doherty, co-ordinator of the South Inner City Drugs Task Force, doesn't agree with such a strategy. "There is a fatalism based on the notion that once people are junkies they will always be junkies and the idea is to help them to use as safely as possible," he says. Mr O'Doherty says this notion of eliminating risks with regard to taking heroin is not possible.

But all sides of the debate on how best to tackle the drugs issue agree on the root cause of the problem: social disadvantage. The evidence for this, according to Mr O'Doherty, is obvious. "If we had eight heroin deaths in Castleknock, there would be a full public inquiry . . . but this has been confined overwhelmingly to the children of the poor. Life in the inner city is cheap."