Biosensors and Disaster Response March 2011
The massive earthquake and tsunami that recently devastated northeastern Japan exacted an enormous human and financial toll. Among the disaster's many long-term effects were disruptions in essential infrastructure for food, water, and sanitation across large areas. In addition to the hundreds of thousands of individuals whom the disaster left homeless and in desperate need of food, water, and shelter, more than 1 million households were still without running water more than a week after the disaster. Vital service disruptions on such a large scale carry with them dangerous—and potentially deadly—public-health risks, including the threat of disease from tainted food and water, lack of adequate sanitation, sewage discharges, and environmental hazards (including decaying plant and animal matter). Besides helping disaster victims cope with these hazards, responders also needed to search for disaster survivors and locate dead victims (whose bodies may also pose health hazards). Biosensor technology can play valuable roles in helping responders and victims to cope with the many challenging circumstances they face and can also help restore vital services (like running water) to safe operation quickly. Unfortunately for the victims and responders in Japan, however, biosensor platforms—except, notably, "whole-organism" biosensors (search-and-rescue [SAR] dogs)—have yet to enter into widespread use in disaster-response and recovery operations. This Viewpoints discusses the kinds of roles that biosensors could play in future disaster-response and recovery operations—providing that biosensors become durable enough, inexpensive enough, and easy enough to use to displace current disaster-response best practices.
Biosensors are an ideal technology for rapidly detecting and measuring the very kinds of threats to human health and safety that are endemic to disaster areas. For people who survive a disaster's direct effects, disease is typically the most serious and immediate threat to human life. Diseases like cholera, hepatitis, and tuberculosis can spread rapidly in areas lacking adequate sanitation and clean water because of disaster-inflicted damages. Regional and seasonal factors can also affect disease risks; for example, malaria threatened victims of the recent disaster in Pakistan, where extremely severe summertime floods grew to cover nearly a fifth of the country's total land area, killing thousands, displacing millions, and helping to create ideal breeding conditions for malaria-carrying mosquitoes. Similar malaria threats could have emerged (but, fortunately, did not emerge on a large scale) following the 2004 Indian Ocean tsunami. And disasters that affect urban areas can damage sewage and water-treatment facilities, turning such human-health assets into new vectors for the spread of disease. Biosensors' ability to detect pathogens present in food, water, or the environment rapidly and with high specificity could help reduce the spread of disease in disaster-affected areas dramatically.
Unfortunately for stakeholders, the realities of disaster response currently do not favor the widespread deployment of biosensor platforms for pathogen detection in disaster areas. Disaster response is far from being a monolithic practice; response efforts can vary significantly in character and extent from one disaster to the next and from one area to the next. But some government agencies and military organizations do specialize in disaster response and follow sets of best practices—that, unfortunately, tend not to include using biosensors to test food and water supplies. Instead, such organizations still tend to rely on visual inspection and, if available, proxy information (such as food's temperature and moisture exposure). For example, the US military's current guidelines for inspection of humanitarian daily rations (HDRs)—standardized ready-to-eat meal packages for humanitarian-relief purposes—contain detailed instructions for visual inspections of packaging and food contents, including diagrams of specific HDR meal types and descriptions of visual, olfactory, and taste cues that could indicate spoilage. Biosensors could simplify such inspections substantially or even eliminate the need for inspections altogether. For example, simple colorimetric biosensors that detect odorant products from food spoilage or the presence of common foodborne pathogens could integrate into HDR pallets or even individual HDR packages. HDR recipients could then verify before consuming the contents whether an individual package's contents are safe to eat. Such sensors could simplify HDR delivery and reduce personnel requirements through eliminating inspections. But although package-integrated food-monitoring sensors have been part of many US military research projects in the past decade (and continue to be an area of interest for military-logistics-research agencies), systems have not seen widespread deployment. Cost is not the only limiting factor that prevents widespread uptake of package-integrated biosensors for HDRs and nonmilitary relief supplies. Organizational priorities for professional disaster responders tend to be skewed heavily in favor of delivering sufficient supplies to an affected area as quickly and thoroughly as possible to address immediate human needs; such priorities are understandable in view of the exigent circumstances following a disaster.
Similarly, water-quality-monitoring biosensors could prevent disease and save lives in disaster-affected regions, but such sensors have seen little deployment among professional response organizations. It is not the case that such organizations are not interested in water-quality-monitoring biosensors or ignorant of the benefits they can bring. Rather, it appears that the exigency and economics of disaster response heavily favor proactive prevention instead of testing. In areas where water service has been compromised, responders often advise disaster victims to assume all water is contaminated and boil or filter it before drinking. But it may not always be possible for disaster victims to treat water, and presuming any water source is tainted can bring with it problems of its own, including unnecessarily avoiding potential sources of clean water. Such an analysis helps explain why the US military may have a uniquely high potential to begin adopting biosensors for monitoring water sources in disaster areas within the next five years. A decade-old US military report advocates deploying handheld luminometers to field personnel for rapid waterborne-pathogen detection—but in a force-protection role, not a humanitarian role. Although no indications suggest that luminometers have entered wide deployment for military-force protection, autonomous biosensor networks are currently undergoing testing for force-protection purposes as part of the US military's Aqua Path research program. Sporian Microsystems (Lafayette, Colorado) developed the sensors, which reside in rugged self-contained buoys that form ad hoc wireless networks with one another and broadcast the status of water in reservoirs, canals, and other open bodies of water. When systems like Sporian's become operational in a force-protection role, economies of scale could develop quickly that can help such systems spread to disaster-response roles as well.
Search, Rescue, and Recovery
Preventing disease outbreaks following a disaster is very important, as is ensuring that victims have sufficient food and water to survive in the near term. But responders' highest priority following a disaster is to locate and rescue any living victims, many of whom may be seriously injured or trapped within damaged or collapsed structures. Search-and-rescue operations are one aspect of disaster response in which biosensors already commonly play a very important role. However, these biosensors are not technology platforms but rather highly trained SAR dogs that are adept at navigating rubble piles and detecting trapped victims by scent from a quarter mile away or more. Not only are SAR dogs remarkably effective at their task, but they also can work autonomously across large swaths of difficult terrain (such as rubble from collapsed buildings), freeing their handlers to engage in other activities within the dogs' vicinity. But SAR dogs are not ideal biosensor platforms in every respect. For example, SAR dog handlers often have difficulty in keeping their dogs motivated in cases where the living victims to find within large and complex areas of rubble may be few. SAR dog handlers who deployed to the World Trade Center following the events of 11 September 2001 reportedly used fake victims to help keep their dogs' morale up; other disaster responders would hide themselves in the rubble deliberately for the dogs to find so that the animals did not become demoralized after dozens of hours of fruitless searching.
Technology-based biosensor platforms do not have morale problems. However, such platforms are also still very far from offering performance, versatility, ease of operation, durability, and even cost points that are comparable with SAR dogs'. Electronic-nose researchers often tout their sensing systems' superiority to alternative sensing platforms, such as gas chromatographs, luminometers, microfluidic biosensors, and, of course, SAR dogs. But even if electronic-nose technology evolves to the point at which it is competitive in detection performance with an SAR dog's olfactory sense, SAR dogs are likely still to retain the dual advantages of high mobility and high autonomy for the foreseeable future. Robotics players foresee that autonomous micro aerial vehicles (MAVs) equipped with sophisticated multianalyte electronic noses could someday self-navigate around rubble piles, as well as partially collapsed buildings and similar areas where it is difficult or dangerous for even SAR dogs to explore. But although MAV technology is advancing very rapidly, regulatory restrictions on MAV deployment for civilian uses (even SAR operations)—coupled with limitations on MAV range, flight duration, and the difficulty associated with creating electronic noses that are light enough to integrate into a MAV—mean that robots will not replace SAR dogs anytime soon.
The area of disaster recovery (as opposed to disaster response) shows significant promise for technology-based biosensor platforms. When urban water-delivery infrastructure suffers damage from a disaster, bringing systems back online to the extent that they can deliver water safely again can be a very complex task. A large earthquake can damage far-flung components of a water-delivery system in ways that may not be easy to detect and that may admit pathogens into the system. Water-delivery systems in some parts of India have similar problems with widely distributed small vulnerabilities that can admit pathogens into the system, supposedly because of slum dwellers' tapping into water systems illicitly and creating small breaches. Inline waterborne-pathogen-detection systems that can integrate into municipal water-infrastructure elements could greatly speed recovery of water-delivery-system capacity in disaster-affected regions. Such systems are already entering commercialization and may yet play a role in helping to restore water service in Japan in the very near future.