A growing body of evidence suggests that crime and incarceration are associated with severe physical and mental strain, including stress, trauma and high rates of chronic illnesses such as diabetes, asthma and hypertension, according to Columbia University’s Mailman School of Public Health.

Public health experts increasingly stress that mass incarceration is a public health issue. They believe addressing it requires more and better communication between policymakers in the criminal justice system and those in public health institutions whose job it is to safeguard the health and well-being of our communities.

“Mass incarceration is not just 2 million people who go to prison in a year,” explains Ernest Drucker, PhD, an adjunct professor of epidemiology at Mailman and author of A Plague of Prisons: The Epidemiology of Mass Incarceration in America. “It’s the phenomenon that 2 million people out of a population in which mass incarceration is concentrated go to prison and what that means not only for them, but their families, their communities and the society as a whole.”

While individuals are incarcerated, they also risk acquiring infectious diseases that may be transmitted to members of their families and, by extension, the communities to which they return. In addition, “the criminal justice system may also undermine other social determinants of health and healthy behaviors, such as school completion and substance use,” says Mailman’s public health initiative.

Indeed, those who are incarcerated may be out of sight and out of mind to many in our society. But prisoners do come home. Every prisoner is an individual who faces the personal risks and consequences of incarceration. But those who are incarcerated are also members of a larger population group that includes family, social networks and communities. “Because they’re not just the only person in prison on their block, the effects of incarceration extend beyond the individual,” Drucker says.

The United States has the largest prison population in the world. The upward trend in U.S. incarceration rates began in the 1970s and continued through the 1980s, fueled by arrests and convictions for drug offenses.

Interestingly, according to a recent report published by the National Research Council and Institute of Medicine, high incarceration rates offer opportunities to treat and care for vulnerable people who might not otherwise seek medical services or have access to health resources. But prisons aren’t the ideal settings for medical care and treatment.

“Prisoners, as well as jail inmates, are more likely than the general U.S. population to be unemployed, poor, black or Hispanic, homeless and uninsured,” according to the report. “And these social variables are all strongly associated with poor health.”