"The shutting down or dramatically reducing the flow of new and relevant information in an era when our society often thinks from one tweet to the next ... means even credible work that's been done has basically been forgotten," he said.
No New Gun Research Students
Wintemute said even though existing gun data included many conditions that haven't changed, opponents can easily disregard it as being old and therefore irrelevant. He added that repeating this research requires real time research, which will take years to conduct and require a labor force that no longer exists.
As a result of researchers leaving his field and students steering clear of it because of funding concerns, Wintemute said the labor force available to dive back into gun violence research is virtually nonexistent. He estimated that only 12 or 15 people in the whole country are still researching gun violence because only a handful of nonprofits are willing to fund it.
"I don't think there's anyone at the CDC who has done significant work in this area in a decade," he said.
David Hemenway, a professor at the Harvard School of Public Health who specializes in injury research, said he cannot "in good conscience" tell his students to pursue careers in gun violence research.
"Don't write your dissertation about guns because it's not going to get any money," said Hemenway, who is considered one of the top gun violence researchers in the country. "All this knowledge is not going to be worth it to them, which is sad."
Wintemute said it's become a tough field to enter because researchers worry about death threats, adding that he himself was threatened by gun manufacturer Bruce Jennings, who founded B.L. Jennings Firearms and Bryco Arms in California. It has since gone bankrupt.
"The work is very controversial," he said. "There are some very angry people out there."
More Questions Than Answers
The act of inserting a single gun question into a survey has become increasingly difficult for Hemenway over the years, he said. For instance, when he asked to include whether families owned guns in a survey that had questions about how many alcoholic beverages people drank and how many cigarettes they smoked, he was turned down.
"If you want to know the simplest things, we don't know," he said. "We're not sure even what percent of houses have guns."
Some studies claim 33 percent have guns, while others estimate up to 59 percent, he said.
"It's not a crucial thing, but you'd think we would know that," Hemenway said. "We really have no idea how many guns there are."
When he was arguing to get the National Violent Death Reporting System started a few years ago, he used to give people a "pop quiz." He would ask, "Where are youths most likely to obtain the weapons they use in acts of violence?" and "When a firearm is used in a homicide or suicide, what is the typical length of time between the purchase of that firearm and the occurrence of the violent act?"
The answer was always the same: We don't know.
Still, many things have changed for the better since the Newtown, Conn., shooting, he said.
"First, the CDC can say the word 'guns,' and we have a president who is willing to talk about guns," Hemenway said, adding that a recent Quinnipiac University poll found that 91 percent of Americans wanted universal background checks for gun purchasers.