In addition, blood lead levels in a community appear to play a role in the link between guns and suicide, the study suggests. A prior study by the first author found that Massachusetts towns with more guns had higher child blood lead levels. The new study found that towns with higher child blood lead levels also have higher suicide rates—probably due to a connection between lead exposure and mental illness.
The study, published December 7 in the journal Preventive Medicine, is the first to look at both firearms and blood lead levels in an examination of suicide. Study co-authors included first author Christian Hoover, MPH ’23; Aaron Specht, visiting scientist in the Department of Environmental Health; and David Hemenway, professor of health policy.
The researchers analyzed nine years’ worth of data (2011-2019) for all of Massachusetts’ 351 cities and towns. Data included the number of firearm licenses, the number of suicides, and blood lead levels. The analysis also took into account factors such as poverty, unemployment, and armed forces status.
The study found that people living in Massachusetts towns with higher levels of firearm licenses had higher rates of firearm suicide and thus had higher rates of overall suicide. Previous studies have uncovered similar links between firearm availability and suicide, though this study appears to be the first to examine these links within all cities and towns of a single state.
Additionally, the researchers found that pediatric blood lead levels—as a proxy for lead in a community—were strongly associated with all types of suicide, as well as with firearm licensure. The authors suggested that lead exposure may be contributing to suicidality by harming people’s mental health. Previous studies have suggested links between lead and mental illness, although much remains unknown, the authors wrote.
The two studies of Massachusetts towns, taken together, suggest that firearms may increase suicide rates in two ways—by providing ready access to the most lethal common suicide method, and by increasing exposure to lead in the family and possibly the community.
Read the study abstract: Firearm licensure, lead levels and suicides in Massachusetts
Higher rates of firearm licensure linked with higher blood lead levels in children (Harvard Chan School feature)