THE symptoms of Dublin's heroin epidemic are not peculiar to any one part of the city's anatomy. They crop up in different places at different times and prompt different reactions.

But from the outstretched, drug-ravaged arms of the north and south inner-city areas to the increasingly squalid heart of the capital around O'Connell Bridge, heroin is always available somewhere.

There are no addicts waiting for dealers at the junction of Buckingham Street and Killarney Street in the north inner city. Effective community policing - whether bye gardai or community action groups - has secured the area for the moment. So the problem has relocated; now junkies meet their dealers where O'Connell Bridge meets Westmoreland Street.

It is a handy spot for illegal activity of this nature. The steady flow of crowds of shoppers, office workers, tourists and others provides a degree of camouflage for people who cherish their anonymity.

During the day you can see some of the city's junkies threading their way through lunch-time crowds or late-afternoon shoppers. At night you sometimes see the same faces. Many of them need to score more than once a day.

They huddle together beside the phone boxes outside the Abrakebabra fast-food restaurant on the corner of Aston Quay, pick up their £10 deals and drift away to shoot up in a laneway or, perhaps, a public toilet.

This area has been a trouble spot for some time. Last year a man was stabbed to death there. It is the scene of drug-dealing, drug abuse and regular violence. And in recent weeks the volume of trafficking has been on the increase.

For Abrakebaba there seems to be no easy solution. "We're having problems. We've had to ring the police on several occasions," said Jason Harbron, a supervisor at the restaurant.

"We have security on at weekends, and they don't let them in the shop. But when there is no security on there Is nothing really that we can do about it."

Many of the perpetrators are young, hard and hopeless. They are a constant, shifty, presence either outside the restaurant or leaning against the Liffey wall, their eyes alert only to scan for police activity and potential punters. They are there irrespective of the weathers and irrespective of the hour. Some of them have nowhere else to go.

"It is the central trading spot," said Father Sean Cassin of the Merchants Quay Project. "Initially the big attraction was ecstasy and some hash. In recent times you can get a variety of drugs, including heroin.

"All of the heroin-dealing sites tend to ebb and flow depending on the amount of law enforcement there is. I would say there is a link between any policing action on the estates and in saying that I include community group policing - and an upsurge in activity elsewhere," he added.

Garda sources concur with that assessment: "The guys selling there are all the same as those who sold in the flats. They have to have somewhere to go, so they go to O'Connell Street. And the bridge has certain advantages. It is the border between two police jurisdiction - Pearse Street and Store Street - and they can throw stuff into the river," one source said.

The sense that the problem is spiralling out of control at O'Connell Bridge is heightened by Father Cassin's experience: "We are seeing increasing levels of violence against addicts and homelessness. The level of homelessness is somethiug we are particularly worried about.

He said the majority of pushers were engaged in trading drugs to maintain their own habits. As pusher-addicts they fall through a hole in the "junkies we care, pushers beware" philosophy of community action groups. Intimidation, or fear of intimidation, has forced them out of the estates and on to the streets. Surviving on the streets brings a new level of desperation into lives that are already bleak.

The current situation has not gone unnoticed by the Garda. Traders have been quick to complain and call for an increased police presence, but the dealers are not easy to catch. "We've been hitting it hard for the last few days, and there have been some seizures, but it is very dangerous for us," the Garda source said.

The danger is the risk of being charged with police brutality. The dealers either keep the heroin in their hands or in their mouths, so the only way to catch them is by the throat, to make sure they don't swallow the evidence, "That's fine if you've got the right guy but if you don't ... it's very dangerous."

That problem is compounded by the fact that it is difficult to distinguish buyers from sellers and the fact that there can be any number of small-time dealers there.

Some gardai also resent having to take such a risk for scant reward. "You would know if you were getting a good-sized dealer. He'd have £1,000 or £500 in his pocket. These guys would be lucky to have £50 in their pockets. They are just selling ten £10 bags to get two for themselves."

Nevertheless, gardai have been hitting the area with some success. The concerns of residents forced the addicts out of the flats and on to Dublin's mean streets, and the concern of retailers has led gardai to crack down on their street activity.