Here's How Dozens Of Scientists At One Of America's Top Labs Were Exposed To Anthrax
None of the 75 scientists affected in a reported safety breach at the Centers for Disease Control in Atlanta have shown symptoms of anthrax. And anthrax isn't contagious, so the exposures won't endanger the broader public. But the incident still reveals the limits of safety precautions even under the most controlled possible circumstances.
Even at the CDC, and even when some of the world's most dangerous bacteria are involved, there's no such thing as absolute safety.
According to the New York Times, the anthrax exposures took place after a sample of the bacteria was exposed to chemicals meant to render it harmless. This was a new method for disarming anthrax, which is typically de-activated through a radiation-based process. Scientists believed the chemicals had rendered the samples inert, and they were moved to a laboratory with less stringent safety requirements.
The scientists were wrong, and 75 were exposed to live samples of the potentially deadly Ames strain of anthrax.
CDC spokesperson Benjamin Haynes gave Business Insider a sense of how and why this mistake was made. According to Haynes, anthrax samples are usually tested 48 hours after being exposed to radiation, since that's how long it would take for radiation-treated anthrax to begin growing spores again if it hadn't been rendered inactive. This time, scientists were using a new chemical-based process for de-activating anthrax.
After two days, if spores aren't developing on a sample, it can be assumed that the disease has been neutralized and that the sample can safely be moved to a less secure lab. "It would have been tested after 48 hours," Haynes says, "and if that sample showed that spores were reproducing then it wouldn't have worked and they would have reapplied the [chemical] process."
A laboratory employee - who has now been reassigned within CDC for the duration of an internal and multi-agency investigation that will include the Department of Agriculture - mistakenly tested the samples after 24 hours instead. At that point, the samples were not showing any additional spore growth. However, growth wouldn't have happened until the 48-hour mark. "When they reviewed the spores after 24 hours there was no growth and they believed it to be inactive," Haynes said.
So the anthrax was moved to a less secure lab environment on the assumption that it had been tested 48 hours after the chemical de-activation process had started. In fact, scientists were almost an entire day away from being able to tell whether the anthrax samples were safe for human exposure.
As University of Maryland professor and pathogen control expert John Steinbruner explained to Business Insider, this was a relatively small incident. "It looked like just a normal kind of mistake," Steinbruner told Business Insider. "This is the kind of thing that can happening dealing with a new technique and discovering it wasn't as effective."
In a way, the occasional breach is almost the price of advanced scientific research into deadly pathogens.
"It's an occupational risk," Steinbruner explained. "Even if you're working under containment conditions, those conditions can break down. They don't always work. Mistakes will be made. These pathogens are very robust."
While this mistake didn't threaten the public, it isn't hard to imagine a much more broadly threatening incident developing from the same sort of errors.
As Steinbruner notes, the SARS virus has escaped Biosafety Level 3 containment three times. Experiments with potentially human-to-human transmissible versions of the H5 N1 "bird flu" virus were performed under Biosafety Level 3 containment in Wisconsin and the Netherlands. Steinbruner considers this to be inadequately secure. He says the bird flu experiments should have taken place at Biosafety Level 4, given the deadliness of the virus and the dangers to the general public.
In Steinbruner's mind, there isn't enough centralized oversight of that kind of research. "Anybody active in that territory ought to be subjected to informed oversight forcing them to justify what they're doing," Steinbruner says. "That mechanism is not in place."
The incident at CDC shouldn't be cause for broader panic. It's still a reminder that mistakes can happen even in the most professional and secure lab environment in the country - and, by implication, just about any other lab in the world.