NEXT week, the United Nations Security Council will hear evidence about Iraq鈥檚 biological warfare capability. The news will not be good. In March, the UN special commission investigating Iraq鈥檚 weapons of mass destruction, made the disturbing announcement that the government could not account for some 26 tonnes of a growth medium suitable for culturing bacteria. Ostensibly for medical research, the growth medium was imported from the West in 1989 (the UN will not say from whom) at a cost of several million dollars. Iraqi officials claim the material has now been destroyed but that the paperwork relating to its disposal was lost during rioting.
UN investigators find the whole story hard to swallow. A few kilograms would have been sufficient for legitimate medical purposes. The rest, they say, would have been enough to cultivate two or three tonnes of the sort of bacteria that can be used in biological weapons.
Other evidence also suggests Iraq has a biological weapons programme. Only a handful of bacteria and viruses are suitable for biological weapons. The list includes anthrax, tulaeremia, cholera and bubonic plague. These bacteria must be tough enough to survive the descent through the atmosphere and virulent enough to quickly infect as many opposing soldiers as possible. At the end of 1994, a UN inspection team uncovered several kilograms of cultures of cholera, tuberculosis and bubonic plague at an Iraqi biotechnology research centre. The centre was supposedly designed to manufacture proteins for use as a food source for livestock and as fertiliser. But it was equipped with facilities such as incineration chambers and secure, sealed clean rooms built to a standard that is unnecessary for protein manufacture but that could be used for producing pathogenic cultures. According to Timothy Trevan, the spokesman for the UN team, Iraqi claims that these activities constitute legitimate medical research 鈥渁re quite frankly, implausible and ludicrous鈥�.
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Deadly dust
Large scale growth of lethal bacteria is only one stage in producing biological weapons. The culture, a soupy liquid containing bacteria, must then be dried to a powder consisting of particles between 2 and 10 micrometres in diameter 鈥� the size that is most likely to be retained in the lungs. The powder is released upwind from the area under attack by aircraft carrying crop dusting equipment or from modified rockets and bombs. So far, says Trevan, inspections have not revealed any hard evidence that such equipment exists.
Western intelligence agencies suspect that Iraq has been trying to develop such weapons for some time. During the Gulf War, NATO troops were inoculated against a range of biological agents. They were also equipped with overgarments and gas masks to prevent skin contact with and inhalation of airborne bacteria says Graham Pearson, a chemist who heads the Chemical and Bacterial Defence Establishment (CBDE) at Porton Down in Wiltshire.
Knowing when to don this equipment is another matter. 鈥淕oing into Desert Storm our capability to detect biological weapons was practically nonexistent,鈥� says Jim Hansen, deputy head of the Pentagon鈥檚 programme for biological detection. NATO manuals even state that the first sign of biological attack is likely to be a sudden increase in the number of soldiers reporting sick. That is set to change.
British and American scientists are developing techniques to detect biological weapons before they can affect an army. During the Gulf War British forces tested a prototype of such a system developed by the CBDE. It consisted of a mobile laboratory in the back of a Land Rover truck that sits upwind of the site it protects. It works by first measuring background levels of biological material such as pollen and other airborne particles such as dust. It then compares samples taken from the battlefield to see how conditions are changing. For example, the lab monitors the levels of particles in the 2 to 10 micrometre range 鈥� a sudden increase could signal an attack.
Next the system decides whether the particles are biological in nature. This is done by subjecting the sample to the enzyme luciferase which fluoresces when it reacts with adenosine triphosphates, chemicals that are present in all living cells. The amount of light produced indicates how much living matter is present and this, again, is compared with background levels. If an abnormality shows up, antibody tests on the sample can determine if specific pathogens are present. A positive result allows troops downwind to don their protective gear before the bacteria reaches them.
Obviously speed is vital 鈥� a delay could give time for the lethal cloud to drift over the army before the alarm could be raised. The prototype completed its battery of tests in twenty minutes but most of this time was spent transferring the samples from one testing area to another. So scientists at Porton Down are currently developing a system that samples air continually and automatically produces results in under three minutes.
The US Army also has a helicopter-mounted detection system. During the Gulf War it initiated a crash programme at the Los Alamos National Laboratory in New Mexico to detect airborne particles at distances of up to 30 kilometres with a LIDAR (light detection and ranging) system. The idea is that small particles in the atmosphere reflect light from a powerful laser and the frequency of the reflected light depends on their speed 鈥� a phenomenon known as the doppler effect. By measuring the amount of reflected light and its frequency, scientists can work out the density of the particles and the way they are moving.
This information alone cannot determine what sort of particles are present, says Ken McKenna, a physicist working on the project. However, biological weapons would be released at low altitude over a limited area forming characteristic cigar-shaped clouds as they move near the ground. This cloud would stand out from background levels of dust and pollen that tend to be evenly distributed, notes McKenna. In tests, he says the system was able to distinguish clouds of kaolin, a powdered clay that simulates the motion of bacterial clouds, which was released from crop-dusting aircraft in the desert near Los Alamos.
It may even be possible to determine what type of bacteria are present by illuminating them with a powerful ultra-violet laser beam and analysing the way they fluoresce. 鈥淯ltraviolet lasers have great potential and we are conducting research to develop the technology for the battlefield,鈥� explains McKenna.
杏吧原创s at the Naval Research Laboratory in Washington have developed a handheld device that also relies on fluorescence. When antibodies and bacteria react they form bonds that fluoresce when bombarded with light. This produces a characteristic spectrum that can be used to identify which bacteria are present. Frances Ligler, a biochemist at NRL, has exploited this phenomenon by coating one end of an optical fibre with antibodies and attaching to the other a laser, a light sensitive diode and a computer that can analyse the signal it produces. The test consists of shining the light down the fibre and analysing the fluorescence produced by the bonds being formed at the tip. The device is the size of a laptop computer and produces results within minutes.
Gene manipulation
In the meantime, biological weapons are becoming more sophisticated. Antibody tests are available for most of the known biological agents. But according to Pearson, it is possible to manipulate the genes of harmless bacteria so that they produce potent toxins such as ricin. Antibody tests would be useless because they are unable to distinguish between the harmless and lethal varieties. The only way to spot the difference is by analysing the DNA structure. Such techniques are now being developed in civilian medical programmes, says Pearson. They work by extracting DNA from the bacteria and replicating it a millionfold with a technique known as polymerase chain reaction amplification. This gives sufficient DNA to tell if the structure has been tampered with. But, the techniques take up to an hour 鈥� too long for use on the battlefield.
Obviously, detecting biological attacks will only become necessary if wayward countries manufacture biological weapons and threaten to use them. Pearson says there is no doubt that an effective system for monitoring the proliferation of biological weapons would deter such activity. Such a system does not exist. However, the Biological Weapons Convention, drawn up in 1972 and signed by 133 countries including Iraq, could suffice. Signatories agree not to manufacture biological weapons but the convention does not allow the claims to be checked. Governments worried by the example set by Iraq now want this to change. In July their representatives will meet in Geneva to discuss how.