Half of the residents of Chicago have witnessed a shooting by the age of 40 with Blacks significantly more likely to have done so than whites, according to a study published on Tuesday.

The study, published in the journal JAMA, involved more than 2,400 inhabitants of the midwestern US metropolis who were born in the early 1980s through the mid-1990s.

On average, the survey's participants were 14 years old when they were first exposed to gun violence, defined as being shot or seeing someone else being shot.

Fifty-six percent of the Black and Hispanic participants had experienced gun violence before the age of 40 compared with 25 percent of the white population, the study found.

By the age of 40, 6.46 percent of the participants had been shot and 50 percent of the respondents across all racial categories had seen someone shot.

"Black people in particular are often living in a very different social context, with far higher risks of seeing and becoming victims of gun violence," said Charles Lanfear of the University of Cambridge's Institute of Criminology, the lead author of the study.

"We expected levels of exposure to gun violence to be high, but not this high," Lanfear said in a statement. "Our findings are frankly startling and disturbing."

Lanfear said a "substantial portion of Chicago's population could be living with trauma as a result of witnessing shootings and homicides, often at a very young age."

Exposure to gun violence can contribute to "everything from lower test scores for schoolkids to diminished life expectancy through heart disease," he added.

Seven percent of the Black and Hispanic participants in the study had been shot themselves by the age of 40 compared with three percent of the white participants.

The study extended over several decades. Gun violence reached a peak in Chicago in the 1990s and then began to decline. It has surged again, however, since 2016.

Other major US cities also have high rates of gun violence but it is particularly prevalent in Chicago, the third-largest city in the country.

According to another JAMA study published in December, young adult males living in certain neighborhoods of Chicago in 2020 and 2021 had a higher risk of suffering a firearm-related death than US military personnel who served in Afghanistan or Iraq.

In 2021, excluding suicides, nearly 21,000 people were killed by guns in the United States, according to the US health authorities.

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