For nearly two years now, Syria has been embroiled in a gruesome civil war that has so far claimed thousands of lives. Cruelties in the region reached a climax in past weeks after alleged reports of chemical weapons use against civilians were made. So far, it’s unclear which side – the government or rebelling opposition – was responsible for the heinous act, and little does it matter for those struck down by the chemical attack. UN officials are currently deployed – and have actually been attacked by snipers during a tour – in order to assess the situation and confirm whether or not chemical weapons were deployed. How do chemical weapons like sarin nerve gas affect the human body, and how can it be detected beyond the obvious onslaught (showing footage of devastated people isn’t proof enough; you need to show that those people were hit by chemical weapons and not something else) ?

Speaking to ABC science, Dr David Caldicott an emergency physician and senior lecturer at the Australian National University, is pretty convinced chemical weapons were indeed deployed on the people of Syria. The substance in question is most likely a type of chemical known as an organophosphate. You’d be surprised to know that some of you might have already been exposed to organophosphates, albeit in a tiny concentrations, through ingestion of food derived from sprayed crops. This class of chemicals include many of the insecticides we use every day, however they’re also deployed in cruel chemical weapons like sarin, soman, tabum, and VX. The main difference is that the warfare-grade organophosphates are “several thousand times” more potent than everyday organophosphate insecticide, according to Dr. Caldicott.

“It’ll probably become very obvious very quickly whether an organophosphate has been used, more difficult than that will be determining what sort of organophosphate that was, and even more difficult than that who was responsible for its release,” says Caldicott.

Organophosphates inhibit an enzyme called acetylcholinesterase at the nerve junction (synapse), responsible for  regulating the amount of the neurotransmitter acetylcholine crossing nerve synapses. Acetylcholine is one of the most important neurotransmitters in the brain, signaling tasks to the body’s autonomic nervous system. Depending on frequency and concentration, acetylcholine  controls things such as heart rate, respiratory rate, salivation, digestion, pupil dilation, and urination.

(c) AP

It’s clear that inhibing the acetylcholinesterase enzyme – which can be resembled to a on-off switch – can have a devastating impact on living beings.

“You can imagine that if you block one of the major ‘off-switches’ of the body, and are left with all the lights turned ‘on’ all of the time, the body might run into trouble. With an extremely rapid build up of acetylcholine in the synapse, things like secretions, respiratory problems, and muscular dysfuntion can go on unattenuated,” explains Caldicott.

“And that’s really how people suffer and die.”

Scientific security analysts can probe whether or not a person has been contaminated by organophosphates by taking urine and blood samples.

“Early on following the exposure to a military organophosphate you may well see the breakdown products of metabolism in the urine, but after it’s been secreted in the wee it’s very difficult to detect.

“If someone has got very low levels of functioning acetylcholinesterase in their blood, then they’ve probably been exposed to an organophosphate, because the poison has bound to it and inactivated it.

“Depending on the toxicity of the agent used, how much was involved, how long patients were exposed and how they were exposed, enzyme levels can start to return to normal levels from several days to several weeks post-exposure.

“What is more difficult and more problematic, the later we are in the process of analysis, is working out what sort of organophosphate has been used.

“That is the real test for the inspectors, particularly a week down the line.”

Caldicott says it is unclear whether or not military-grade chemicals have been used.

“You could mimic this effect by using a high concentration and large volumes of a simple insecticide,” he says.

Charles Duelfer, the former head of U.S. weapons inspection teams in Iraq, said the U.N. experts will be looking to collect evidence from witnesses and survivors of last week’s attack, including samples that can be analyzed later.

“They’ll be looking for remnants of the munitions, which could be sophisticated munitions that a military would have — or if it turns out, unexpectedly, to be the case that the insurgents had cobbled together some sort of CW capability, maybe they’ll find that,” Duelfer said.

UPDATE: In the meantime, CNN has footage of alleged chemical attack victims. Be warned viewer discretion is advised, as the video is most, most graphic.