Police are reporting that Sergei and Yulia Skripal most likely came into contact with the nerve agent, Novichok, at their home, and that the highest concentration of the agent was on their front door.
Prof Alastair Hay, Professor Emeritus of Environmental Toxicology, University of Leeds, said:
“The police have reported that the Skripals may well have had the greatest contact with the nerve agent as a result of something being on the door of their house. From what the police are saying this represents the highest contamination they’ve recorded to date.
“Earlier reports suggested some contamination may have occurred in the car. It is quite likely that if either of the pair had had contamination on the palm of their hand from the house door handle this may have been transferred to the door handle of their car. The air conditioning system in the car has always seemed an unlikely source of exposure as effects would have been almost immediate because inhalation would have had to have been the route of exposure.
“It is important to note that it is the novichok family of nerve agent that is the focus of the investigation. We know little about them in comparison to other better-known nerve agents like sarin and VX. It is quite feasible that novichoks were developed to encompass some that were fairly volatile and others that were much more persistent. The persistent agents would be ones where skin contact would be where contamination generally occurred.
“We know from studies done on the persistent nerve agent VX that effects are delayed and that symptoms will occur a few hours to even some days later. Uptake through some parts of the skin is much more efficient than others – for example the cheek and the back of the ear are 25 times more efficient than uptake through the palm of the hand. Palms, elbows and knees would require more agent to have an effect than if it were on the cheek.
“In situations like the one involving the Skripals, it is likely there would have been delayed onset of symptoms like headaches, feeling nauseous, feeling very weak and possibly vomiting, after the typical exposure occurs through skin contact.
“Clearly one principal focus of investigation will now be the Skripal’s house. But the likelihood of there being any wider risk to the general public is extremely small, as the police have indicated.”
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