AUSTIN, Texas – Scientists have uncovered new evidence that heated political discourse over proposed laws involving marginalized groups, such as debates about the rights of LGBT people, can contribute to an increase in bullying linked to students’ identity in schools. It is the largest study to date to examine the link.

In a new study out Monday, in the journal Pediatrics, scientists at The University of Texas at Austin, Columbia University and Texas State University found that in the run-up to a statewide voter referendum to ban gay marriage in California, young people reported significantly more homophobic bullying. In fact, homophobic bullying peaked that school year and declined after the public debate about the initiative in question, Proposition 8, subsided.

“We think that young people don’t hear what adults and lawmakers are talking about, but they do,” said Stephen Russell, senior author of the paper and chair of the Human Development and Family Sciences Department at The University of Texas at Austin.

Researchers say the study provides empirical evidence that public debates about policies and laws involving marginalized groups can lead bullies to target young people identified as being part of those groups.

“Public votes and voter referendums on the rights of minority groups occur in approximately half of U.S. states,” said Mark Hatzenbuehler, an associate professor of sociomedical sciences and sociology at Columbia University and the paper’s first author. “Our findings suggest that the public discourse surrounding these votes may increase risk for bias-based bullying.”

The study looked at yearly survey data from nearly 5 million middle and high school students in more than 5,000 schools in California from 2001 to 2015 and whether those students experienced homophobic bullying.

The rate of homophobic bullying rose from 7.6 percent of students reporting they experienced this bullying in the 2001-02 school year to 10.8 percent in the 2008-09 school year when the Proposition 8 vote took place. This occurred even as trends in other types of bullying related to race or ethnicity, religion and gender declined. Russell pointed out that the rate of homophobic bullying that year was higher even than the estimated population of LGBT students.

“The data are telling us that straight kids are getting bullied for this, too,” Russell said. “It’s all about what the bullies perceive.”

After peaking in 2008-2009, the rate of homophobic bullying steadily decreased every year after.

Many schools have initiatives to prevent bullying and bias, so the team also examined whether campuses with a Gay Straight Alliance (GSA) club experienced a protective effect against homophobic bullying. They found rates of homophobic bullying in fact were lower on campuses with these clubs during the 2008-09 school year: Homophobic bullying was below 10 percent on campuses with GSA organizations and nearly 13 percent on campuses without a GSA.

The negative impacts of bullying on mental health are well established, but what is not well known is what factors in the culture and society contribute to bullying. Because the paper shows public discourse can play a role, the findings could have implications for discussions of other policy issues that focus on marginalized or minority groups.

“Policies and campaigns related to Black Lives Matter, bathroom bills, immigration — these can be concerning in how they affect the health and well-being of youth,” Russell said. “The public health consequences of these very contentious and media-driven discussions are more important than we knew.”

Yishan Shen of Texas State University and Elizabeth Vandewater of The University of Texas at Austin also contributed to the research.

Funding for the research was provided by the Communities for Just Schools Fund Project at the New Venture Fund, the Priscilla Pond Flawn Endowment at The University of Texas at Austin and the Eunice Kennedy Shriver National Institute of Child Health and Human Development.