A new study shows that the greater the density of alcohol outlets, especially bars, the higher the rates of assault witnessed in the neighborhood, especially in urban areas. Roughly 15 years of research has shown that the availability of alcohol - as measured by the number and types of alcohol outlets - is directly related to interpersonal violence. The same conclusion is supported by the first study that uses hospitals' data.

"Hospital discharges are carefully tracked throughout the state of California and provide accurate assessments of causes of injury," said Paul J. Gruenewald, senior research scientist at the Prevention Research Center and first author of the study. "Included among these are 'assaults,' or injuries that arise from some form of interpersonal violence. About one out of 10 assaults recorded by police are severe enough to require hospitalization. Thus, assaults recorded in hospital discharge data represent the most severe cases of interpersonal violence, short of death, that occur in the state."

Using hospital-discharge data on violent assaults rather than crime reports from law enforcement officials also helps to control reporting biases, added Richard Scribner, professor of preventive medicine at Louisiana State University Health Sciences Center. "For example, residents of a neighborhood with high levels of police mistrust might be unlikely to report an assault."

Researchers collected six years' worth of data from 581 consistently defined zip-code areas in California. Features of local populations, such as household sizes, and places, such as retail markets, were correlated with one measure of violence: hospital admissions related to violent assaults.

"We found that rates of violence increase in areas with growth in the numbers of bars and off-premise establishments that sell alcohol," said Gruenewald. "These relationships are independent of changes in other aspects of communities often related to violence, such as poverty or vacant housing."

Gruenewald noted that alcohol consumption at bars or taverns tends to concentrate at-risk individuals within environments that emphasize both drinking and social interactions. "For those individuals with some predisposition to violence, such as young males living in impoverished areas, this is enough to increase violence rates. In addition, high concentrations of off-premise alcohol outlets tend to occur in communities with lower levels of social control, where a variety of other crimes occur - such as illegal drug sales and prostitution - that are related to violence."

"This study represents one of the strongest tests of the alcohol outlet/violence relationship," said Scribner. "There was also an unexpected finding: the degree to which this effect is amplified when spatially lagged effects on adjacent zip codes are considered." This means that the effects of alcohol outlets are found not only in the immediate vicinity, but also in the surrounding neighborhoods.

"These findings are significant from a prevention standpoint because alcohol outlets represent a modifiable characteristic of the community environment," continued Scribner. "Policies targeting the density of bars and off-sale outlets could be used by policymakers to address high rates of interpersonal violence in their communities. After all, violent assaults may only be the tip of the iceberg. Responsible leadership needs to factor in the potential social costs as well as the economic benefits associated with the approval of an additional alcohol outlet."

Gruenewald agrees. "Local city and county planning and zoning boards have the ability to regulate sales of alcohol through outlets," he said. "Although the numbers of alcohol outlets in California have slowly declined over the past decade, concentrations of these outlets in urban areas, particularly impoverished areas of our cities, have continued to grow. Current alcohol licensing practices generally focus upon limiting the numbers of outlets on the basis of population, but this policy is misguided. It would be better to utilize 'distance regulations' to keep down over-concentrations of outlets shown to affect violence."