Although chemical and biological warfare has been internationally condemned since the 1600s, scientific research has continued to uncover chemicals which can have a devastating effect on the nervous system. Indeed, at the end of last year there were reports of an alleged government attack on civilians using an unidentified nerve gas in the city of Homs in Syria. It is thought that Assad’s regime have been developing and stockpiling chemical weapons. If this is true, the situation shows disturbing similarity to Saddam Hussein’s use of the nerve gases against Iranian civilians during the Gulf War in the 1980s.
Interestingly, the discovery of nerve gases was made more or less by accident. The organophosphate (OP) family of nerve gases, including sarin and tabun, were being studied by German scientist Dr. Gerhard Schrader during the 1930s as possible insecticides. Whilst studying these chemicals Dr. Schrader accidentally spilled a drop of tabun onto the bench and, within minutes, was overwhelmed with dizziness and had difficulty breathing. It took him and his colleague three weeks to fully recover from this exposure.
OP nerve gases work by stopping the enzyme acetylcholinesterase (AChE) from breaking down the neurotransmitter acetylcholine (ACh). Normally, when ACh is released by nerve cells it is rapidly broken down by AChE, meaning that it can’t build up around target cells. However, when AChE stops working ACh collects around cells, overstimulating them. The effects are often seen as over-stimulation of muscle cells and glands which produce bodily fluids. After very high exposure to OP a victim will suffer a huge number of horrible symptoms, including, a runny nose, tight chest, blurred vision, shortness of breath, nausea, muscle spasms, drooling, crying, incontinence, vomiting and abdominal pain. In this case, death usually follows quickly, either due to choking or from suffocation caused by overstimulation of the diaphragm. Sarin was infamously used by the Japanese terrorist group Aum in an attack in a Tokyo subway station in 1995, which killed 13 and left thousands with temporary vision problems.
Another family of chemicals that affect the nervous system are anti-cholinergics. Anticholinergics stop ACh from activating receptors on target cell (muscles and glands). As a result, these chemicals have almost entirely the opposite effect to OP nerve gases. The symptoms include a dry mouth, muscle weakness, blurred vision, as well as hallucinations and some pretty strange delirious behaviour. Anticholinergics could have a potential (though still illegal) use as a ‘non-lethal’ weapon to incapacitate people – since people can’t really fight back if they’re delirious. Saddam Hussein was accused of stockpiling the anticholinergic Agent 15 to use in the Persian Gulf War against Kurds and Iranians. Another similar chemical known as BZ was weaponised by the U.S. military during the Cold War. Thankfully, stocks were uncovered and destroyed before it was deployed. BZ was also discovered by accident by a scientist innocently working on digestive disorders.
Despite some of these examples, where dangerous biological weaponry has emerged from otherwise benign research; there would be no sense in avoiding all scientific research in the fear that someone might accidentally stumble across the next weapon of mass destruction. Scientists certainly have a duty to be aware of the potential uses for their work, especially since research is (or should be) freely accessible online. However, ceasing research into potentially hazardous chemicals altogether would inhibit some pretty important discoveries; especially since many chemicals which are beneficial in small doses, could have a lethal ‘dual-use’. Indeed, drugs which inhibit AChE are not just potential biological weapons, they are also currently the most widely used treatment for Alzheimer’s disease.
Perhaps, since the discovery of the occasional nasty seems unavoidable if important biological research is to continue, the best course of action would be to fund counter research into possible treatments.
At the University of Sheffield, Prof. Mike Blackburn and his collaborators have recently developed a ‘bioscavenger’ to mop up OP chemicals, preventing them from attaching to AChE. This kind of treatment will hopefully help save lives in the event of nerve agent attacks. Last year, Dr. Moshe Goldsmith at the Weizmann Institute in Israel mutated a human liver enzyme so that it could break down OP nerve gas molecules. While this research holds obvious benefits to humanity, the implications of this work also raises an ethical dilemma. If the gene code for this newly-evolved enzyme could be put into soliders, we could be faced with a scenario where armies can be genetically manipulated to become immune to chemical or biological weapons. Unfortunately, this hypothetically amazing feat of science could result in an biological arms race…a situation it’s hard to envisage anyone winning.
The Arts and Humanities Research Council has a Neuroscience Ethics Network that bring together researchers from all over the UK. Some of this article has been based on prospective lectures initiated by the Network, intended for undergraduate Neuroscience students. If you’d like to read more about the Network, please click here: http://www.lab.ls.manchester.ac.uk/neuroethicseducation/
Post by Natasha Bray