Biologists Struggle with Push to End Use of Caesium Proposed Switch to X-Ray Irradiators Could Affect Results of Research

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NUCLEAR SECURITY Biologists struggle with push to end use of caesium Proposed switch to X-ray irradiators could affect results of research.

BY JEFF TOLLEFSON

nybody who wants to conduct experiments on mice in Margaret Goodell’s immunology lab must sub- Amit to a host of security measures, starting JIM R. BOUNDS/AP/PA 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 stem- cell 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 every thing 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 Biomedical researchers often use caesium-137 to irradiate cells. to the two types of device, prefers Baylor’s caesium irradiator. Her research has revealed or water; exposure to the substance can cause alternative ways to treat blood is relatively that immune cells called B lymphocytes burns, radiation sickness or death, depend- simple. The NNSA is working with research- recovered more slowly in mice treated with ing on the dose. Caesium irradiators, which ers to pin down the more complicated issue an X-ray irradiator than in those exposed have long been used to eliminate pathogens in of how X-ray irradiators might differ from to caesium. But other immune cells, known supplies of blood as well as for research appli- conventional caesium instruments for other as myeloid cells, rebounded faster after the cations, rely on small capsules of radioactive applications. X-ray treatment (B. W. Gibson et al. Comp. caesium chloride encased in a lead-covered “You talk to the doctors, and they are afraid Med. 65, 165–172; 2015). Because of this, she box. There are more than 800 such devices in that we are going to be taking away their says, “it would be difficult to compare studies US medical and research facilities. devices,” says Maegon Barlow, director of radi- using X-rays to the research that was done ten Several countries — including France, ological security at the NNSA. “But it’s really years ago”. Norway and Japan — are shifting away from trying to facilitate, not force.” For nuclear regulators, the risk posed using caesium irradiators in blood banks The agency is negotiating with the Mount by caesium is clear. The element’s highly because of security fears, and last year the Sinai Health System in New York City to sup- radioactive isotope caesium-137 comes in a NNSA began working with hospitals in the port a new round of studies that will compare powdered form that can be dispersed in air United States to do the same. But finding X-ray and caesium irradiators. Jacob Kamen,

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Mount Sinai’s chief radiation-safety officer, notes that some researchers there have already conducted similar experiments. Peter Heeger, head of organ-transplant research at Mount Sinai’s Icahn School of Medicine, and his colleagues use caesium irradiators when testing immune responses in people who are going to receive organs. To predict whether a CHAMUSSY/SIPA/REX/SHUTTERSTOCK recipient’s body will reject a new organ, the researchers culture B lymphocytes from the organ donor and test them against immune cells from the recipient. But B lymphocytes will not divide unless they are activated — here, by the presence of connective-tissue cells called fibroblasts. Heeger’s team irradiates the fibroblasts to prevent them from replicating during this process. The scientists have run a series of unpublished experiments to determine how much X-ray radiation is necessary to suppress fibroblast growth. “Now we know, and we are now comfortable switching for this particular procedure,” says Heeger. But Goodell says that many researchers Q&A Thierry Mandon would have to conduct lengthy experiments to ensure that they can make the transition without losing confidence in their results. Nor is she convinced that France’s research a switch to X-rays is necessary, given the security safeguards that are already in place. Anybody who needs to use the transformation caesium irradiator at Baylor must present a security badge, enter a personal iden- tification number and then submit to an Thierry Mandon, who became France’s research and higher-education minister last June, has iris scan. And if a person inside the secure vowed to cut bureaucracy in a research system that is undergoing major changes. In 2013, room that contains the irradiator breaches laws were passed to accelerate the consolidation of universities, prestigious ‘grand écoles’ and any security protocols, an alarm automati- research-agency labs into regional clusters that could develop common research policies. cally goes off in the university’s security And in April, Mandon announced measures to further reduce researchers’ paperwork and office. administrative burden. He talks to Nature about what he hopes to achieve in the year remaining “As a biologist, it’s not clear to me what before France’s presidential elections in 2017. case has been made for [caesium irradiators] being an enormous security risk,” she says. What are the most urgent items on announced in March, we plan to increase the Advocates of ending use of the devices your to-do list? ANR’s budget by 10% this year, and by 20% say that the goal is to eliminate the risk To simplify the rules that govern higher next year, to bring it back to €800 million by of nuclear material falling into the wrong education, and research. To have more PhD 2018 — around the same level as its peak in hands wherever possible. The security students and researchers recruited by compa- 2008. We aim to boost the success rate of grant measures in place to protect caesium irra- nies and by the public sector, and so instil a applications to between 14% and 20% in 2017. diators would not necessarily prevent the culture of research in the places where deci- Researchers have been critical of ANR theft of nuclear material by somebody with sions are made. To help universities to develop bureaucracy. We plan to introduce a series of permission to access these instruments, their own sources of income, so that they can 50 reforms, most taking effect later this year, to says Charles Ferguson, president of the Fed- be more independent of the state. To promote a lessen the administrative burden throughout eration of American Scientists in Washing- renaissance of the social sciences. And to spur the research and higher-education systems. ton DC. Efforts to secure nuclear materials the digitalization of higher education. The process of preparing grant proposals for are often focused on this ‘insider threat’, as the ANR will be greatly simplified, as will well as the disposal and recycling of irradia- What about funding? Scientists have warned procedures for their assessment. tors, which can contain enough caesium to that France’s basic research is endangered by pose a hazard for centuries. a lack of funding, in particular by cuts at the What else do you hope to put in motion “I would not want humanity to lose the National Research Agency (ANR). before next year’s elections? benefits of science,” says Ferguson. “But if The ANR has seen its annual budget fall by We want to reinvigorate the social sciences. we can develop alternative technologies around €250 million (US$285 million) since Research in the social sciences remains very that prove comparable and can reduce the 2012, to around €550 million. As a result, the focused on publications — but value will be security threat to zero, I think that’s a good success rate of grant applications is too low, created through greater contact with the thing.” ■ at just under 10%. As President Hollande hard sciences and through social-science