J. Tollefson
May 10, 2016
Citations
0
Influential Citations
1
Citations
Journal
Nature
Abstract
Anybody who wants to conduct experiments on mice in Margaret Goodell’s immunology lab must submit to a host of security measures, starting with a background check by the FBI. That’s because Goodell, a researcher at Baylor College of Medicine in Houston, Texas, uses a caesium-based irradiator to destroy bone marrow in mice that are set to receive stemcell transplants. The US government fears that the radioactive caesium could be stolen to make a ‘dirty’ bomb. Now the US National Nuclear Security Administration (NNSA) is working with scientists to investigate how — or whether — to replace caesium irradiators with less dangerous X-ray technology. Researchers have used the caesium devices for decades, to study everything from immunotherapy to cancer treatment, and some fear that switching to X-ray irradiators will affect their results. Goodell, who has found subtle differences in how the mouse immune system responds to the two types of device, prefers Baylor’s caesium irradiator. Her research has revealed that immune cells called B lymphocytes recovered more slowly in mice treated with an X-ray irradiator than in those exposed to caesium. But other immune cells, known as myeloid cells, rebounded faster after the X-ray treatment (B. W. Gibson et al. Comp. Med. 65, 165–172; 2015). Because of this, she says, “it would be difficult to compare studies using X-rays to the research that was done ten years ago”. For nuclear regulators, the risk posed by caesium is clear. The element’s highly radio active isotope caesium-137 comes in a powdered form that can be dispersed in air or water; exposure to the substance can cause burns, radiation sickness or death, depending on the dose. Caesium irradiators, which have long been used to eliminate pathogens in supplies of blood as well as for research applications, rely on small capsules of radioactive caesium chloride encased in a lead-covered box. There are more than 800 such devices in US medical and research facilities. Several countries — including France, Norway and Japan — are shifting away from using caesium irradiators in blood banks because of security fears, and last year the NNSA began working with hospitals in the United States to do the same. But finding alternative ways to treat blood is relatively simple. The NNSA is working with researchers to pin down the more complicated issue of how X-ray irradiators might differ from conventional caesium instruments for other applications. “You talk to the doctors, and they are afraid that we are going to be taking away their devices,” says Maegon Barlow, director of radiological security at the NNSA. “But it’s really trying to facilitate, not force.” The agency is negotiating with the Mount Sinai Health System in New York City to support a new round of studies that will compare X-ray and caesium irradiators. Jacob Kamen, N U C L E A R S E C U R I T Y