It sounds like the setup to an apocalyptic movie about a pandemic. Live samples of the deadly smallpox virus were found in an unused storage room at the National Institutes of Health (NIH) in Bethesda, Maryland. Also hidden away in that forgotten room were 12 boxes and 327 vials filled with the viruses that cause dengue fever and influenza and the bacteria responsible for spotted fever.

Meanwhile, the Centers for Disease Control and Prevention (CDC) announced in June that an estimated 75 of its scientists had been inadvertently exposed to live anthrax bacteria without proper safety equipment. Last week, the CDC revealed that staffers had mishandled dangerous materials at least four times over the past decade, including transporting pathogens in Ziploc bags and sending a live sample of bird flu to a low-security lab that was ill-equipped to receive it.

This isn’t a cinematic setup. These all-too-real blunders are just the latest in a long history of dangerous mistakes made by those entrusted with extremely hazardous materials, from viruses to nuclear warheads. No one was injured in any of these incidents. However, testifying before Congress last week, CDC Director Thomas Frieden admitted that his agency had “missed a critical pattern … of an insufficient culture of safety.”

Edwin Lyman, a senior scientist with the Union of Concerned Scientists’ Global Security Program, says he isn’t too surprised by the recent lapses.

“There is a level of complacency that creeps in among people who are entrusted with very high value targets and materials,” he says. “In the absence of acute threats, many people let their guard down. They get sloppy.”

Securing Medical and Research Materials

Academic centers have long favored openness over security. When I was an undergraduate at a major state university in the late 1990s, I studied science in laboratories where pathogens and nuclear materials were kept in unlocked refrigerators, sometimes just steps away from classrooms and even kitchenettes.

Many university, research, and medical centers in the U.S. did start improving security after the terrorist attacks in 2001, says Lyman, but the process hasn’t been as comprehensive as many people think.

“Radioactive materials are in such common use, and they have such strong therapeutic and diagnostic value, that the cost and benefit analysis of putting them under greater security is a tough call for many people to make,” says Lyman. “You raise the cost of treatments by increasing security against threats that are usually pretty remote.”

But even remote threats are cause for concern. Medical radioactive materials could fall into the wrong hands and get turned into “dirty bombs”—conventional explosives that disperse radioactive material when detonated.

In 2012, James Blair, a retired U.S. Army colonel and president of the Nashville-based Center for Health Care Emergency Readiness, told members of Congress that “four out of five hospitals, blood banks, and university-based health care research organizations fail to secure what the Defense Science Board characterizes as the greatest immediate nuclear threat from terrorists: medical and research radioactive use materials.”

Debate over this issue heated up in Massachusetts this summer, when state officials began prodding hospitals to replace blood irradiators with more expensive, x-ray-based alternatives. Irradiators, which are used to treat blood before transfusions, contain a dangerous radioactive powder known as cesium chloride, which could be used in dirty bombs. The nonprofit National Research Council (NRC), an independent government agency, has called for a ban on them.

An accidental exposure of cesium chloride in Brazil in 1985 killed four people, contaminated 249, and required 112,000 to be monitored.

When the U.S. Government Accountability Office (GAO) examined the security of blood irradiators in 2012, it discovered that one hospital in an unnamed city had posted the combination to a locked room holding the device on the door frame. Another unnamed hospital stored irradiators in a basement that was open to the public. One of the machines was even kept on a wheeled pallet.

Missing Nuclear Weapons

It’s not just the medical and academic communities that have had a hard time keeping close tabs on dangerous materials. Government and civilian facilities that oversee high-grade nuclear material for weapons and power plants, such as plutonium and enriched uranium, “are chronically unsecured,” says Lyman.

A spectacular lapse of security occurred in 2012, when three peaceful protesters, including an 82-year-old nun, infiltrated the U.S. Department of Energy’s Y-12 National Security Complex in Oak Ridge, Tennessee, where nuclear weapons and fuels are stockpiled. The protesters hung banners, sang songs, and offered to share food with security guards before they were taken into custody.

“That wasn’t a one-off problem,” says Lyman. “It was indicative of many security failures at that site.”

Later that year, employees of Halliburton reportedly lost a nuclear fuel rod that they were transporting across the Texas desert. It was recovered after about a month of searching. In a statement that is less reassuring than the speaker probably intended, a spokesperson from the Nuclear Regulatory Commission said, “It is the first time the loss of a radioactive rod has been recorded by the NRC in at least five years.”

Things don’t seem to have gone much better for the Department of Energy. According to a 2013 report by the GAO, the department’s “record of inadequate management and oversight of contractors” has left the agency at “high risk,” since contractors perform many critical functions, including security. This year, the GAO criticized the Department of Energy’s National Nuclear Security Administration for failing to outline how it will increase safety and security.

The military also has had trouble securing its nuclear holdings. According to a 2014 report prepared by the U.S. Army War College, the U.S. military complex has misplaced more than five tons of weapons-grade nuclear materials over the decades, enough to make more than a thousand bombs. For instance, evidence suggests that 100 kilograms of weapons-grade uranium that disappeared from a U.S. defense contractor in the mid-1960s later ended up in Israel, where it helped fuel that country’s nuclear weapons program.

More recently, in 2007, six cruise missiles topped with nuclear warheads were mistakenly loaded onto a bomber in North Dakota by the U.S. Air Force and flown to Louisiana without proper safety precautions. In 2010, the Air Force partially lost communication with 50 missiles because of a hardware problem.

Much of the public assumes that dangerous materials like smallpox and plutonium are kept under tight lock and key. That does seem to be the case most of the time. But when it comes to such hazardous substances, can any lapses be tolerated?