Nurliza Abdullah, Lay See Khoo and Mohd Shah Mahmood – National Institute of Forensic Medicine (NIFM), Hospital Kuala Lumpur, Malaysia
For Part I of this article see here.
Laboratory Analysis
Chemical weapons & poison analysis
Examination for chemical weapons’ presence resulted in a positive detection of the VX nerve agent and its degradation product, Ethyl methylphosphonic acid (EMPA), on the swabs of the eye mucosa and face as well as in the blood, plasma and urine. The VX nerve agent contains the alkyl methylphosphono moiety in its chemical structure and it is readily hydrolyzed to EMPA. The precursors of VX and its degradation product were also detected on the t-shirt of the deceased. Further analysis also found the presence of VX, various degradation products and its precursors on the deceased’s blazer as well as the presence of VX’s degradation product, EMPA, on the deceased’s bag.
VX is listed as nerve agent under Schedule 1.A.03 of the Chemical Weapons Convention Act Malaysia 2005 and 1997 Chemical Weapons Convention. Ethyl methylphosphonic acid (EMPA), also known as the VX acid, is listed as degradation product of VX under Schedule 2.B.04 of the Chemical Weapons Convention Act Malaysia 2005 and 1997 Chemical Weapons Convention. Other degradation products of VX found on various specimens such as Bis(2-N,N-Diisopropylaminoethyl)sulphide and the Bis(2-N,N-Diisopropylaminoethyl)disulphide are listed under non-schedule reportable chemical (NSRC) QDOC/LAB/WI/PT04 under the OPCW Proficiency Test. On the other hand, the 2-(N,N-Diisopropylamino)ethylchloride is listed as precursor of VX under Schedule 2.B.10 of the Chemical Weapons Convention Act Malaysia 2005 and 1997 Chemical Weapons Convention. Other precursors of VX, 2-(N,N-Diisopropylamino)ethanethiol and O-Ethyl methylphosphonothioic acid are listed under Schedule 2.B.12 and Schedule 2.B.04 respectively of the Chemical Weapons Convention Act Malaysia 2005 and 1997 Chemical Weapons Convention.
The following table summarizes the analysis result for the presence of the chemical weapons on the victim:
# 1 / Specimen: Swabs of eye mucosa
Analysis / Result: VX nerve agent (Ethyl S-2-diisopropylaminoethyl methyl phosphonothioate); VX degradation product Ethyl methylphosphonic acid (EMPA);
VX degradation product N,N-Dimethylaminoethanol
# 2 / Specimen: Swabs of face
Analysis / Result: VX nerve agent (Ethyl S-2-diisopropylaminoethyl methyl phosphonothioate); VX degradation product Ethyl methylphosphonic acid (EMPA)
# 3 / Specimen: Blood
Analysis / Result: VX nerve agent; VX degradation product Ethyl methylphosphonic acid (EMPA)
# 4 / Specimen: Plasma
Analysis / Result: VX nerve agent; VX degradation product Ethyl methylphosphonic acid (EMPA)
# 5 / Specimen: Urine
Analysis / Result: VX nerve agent; VX degradation product Ethyl methylphosphonic acid (EMPA)
# 6 / Specimen: T-shirts
Analysis / Result: VX degradation product Ethyl methylphosphonic acid (EMPA); VX precursor 2-(N,N-Diisopropylamino)ethylchloride
# 7 / Specimen: Blazer
Analysis / Result: VX nerve agent (Ethyl S-2-diisopropylaminoethyl methyl phosphonothioate); VX degradation product Ethyl methylphosphonic acid; VX degradation product Bis(2-N,N-Diisopropylaminoethyl)sulphide; VX degradation product Bis(2-N,N-Diisopropylaminoethyl)disulphide; VX precursor 2-(N,N-Diisopropylamino)ethanethiol; VX precursor 2-(N,N-Diisopropylamino)ethylchloride; VX precursor O-Ethyl methylphosphonothioic acid
# 8 / Specimen: Brown bag
Analysis / Result: VX degradation product Ethyl methylphosphonic acid (EMPA)
Toxicology Analysis
Toxicology result showed evidence of therapeutic drugs for diabetes, hypertension and gout in the blood, urine and tissues. These drugs were consistent with the medical history of the deceased. There were no common pesticides detected in the blood, urine and tissues.
DNA Analysis / Profiling
DNA analysis was performed using the victim’s blood taken during autopsy and his DNA profile was successfully obtained.
Biochemical Analysis
Cholinesterase level detected by the Biochemical laboratory was 344 U/L. The normal range of the cholinesterase level is 5320 to 12920 U/L. In the opinion of the Clinical Toxicologist this means a very significant drop in blood cholinesterase enzyme levels, where the low cholinesterase level could be due to conditions such as intoxication with organophosphorus compounds (cholinesterase inhibitors) and impaired cholinesterase production due to liver diseases. The result was in accordance with the United States Army Medical Research Institute of Chemical Defense’s handbook, with the nerve agents in question being organophosphates.
Discussion / Challenges
The deceased was carrying a North Korean passport with him. Identity of the deceased was known, as it matched the fingerprint in the passport. However, the forensic odontology examination and DNA analysis could not reveal the identity of the deceased which was disputed by the media, as antemortem data were not made available.
Postmortem examination showed no significant marks of trauma apart from the marks of medical intervention. Internal examination revealed non-specific congestion of the internal organs, associated signs of lung edema with congestion and evidence of hypertension with diabetic changes in the kidneys. The significant drop in blood cholinesterase enzyme level was suggestive of an acute exposure to a toxic substance that inhibits cholinesterase. VX strongly and readily binds to acetylcholinesterase and thereby inhibits the vital enzyme’s normal biological activity in the cholinergic nervous system. The positive detection of VX, VX degradation products and VX precursors on the specimens sent to the Centre of Chemical Weapon Analysis strengthened and corroborated the clinical history. Thus, the cause of death of the deceased was given as VX (Nerve Agent) poisoning following the rapid onset of exposure.
There are two categories of nerve agents – the G agents and the V agents. The G agents are non-persistent agents and the V agents are persistent agents. Nerve agents are organophosphates. Many commercially available insecticides are organophosphates, but these are much less potent than nerve agents, which are specifically developed as weapons.
The table below shows the comparative volatility among the nerve agents. From the table, it is obvious that Sarin is the most volatile, whereas VX is the least volatile nerve agent. Comparative LD50 of the nerve agents also shows clearly that VX is the most toxic of all nerve agents. Nerve agents are so powerful because they can be absorbed orally, by inhalation or through the mucosa or skin. Pure VX is available in fluid form and is odorless, with these properties making VX easy to be transported without being detected. Therefore, it is recommended that all airports and high-security buildings should be equipped with the special detector for chemical weapons as a preventative measure.
Two weeks after the incident, The Royal Malaysian Police’s Chemical, Biological, Radiological and Nuclear team as well as the Fire Department’s Hazardous Materials Unit and the government’s Atomic Energy Licensing board (AELB) swept the Kuala Lumpur Airport for toxic chemicals and traces of VX nerve agents, following the positive laboratory findings for VX. The authorities have then declared the airport terminal to be freed from any form of contamination of hazardous material.
Would it have been safer for the emergency responders, mortuary personnel and the public if early detection equipment was made available at the KL Airport prior to the incident? Similarly, all personnel in the hospital mortuaries or the forensic medicine facilities should also be equipped with proper decontamination facility as well as PPE to protect the personnel who will be working with the dead exposed to these toxic chemicals. In this case, hospital personnel were quite fortunate in the sense that the nerve agent in question had high viscosity and remained in fluid form at room temperature, making it confined directly to the victim and not affecting people in close vicinity of the victim. Only when VX is subjected to a high boiling temperature it will transform into gaseous state and could cause more casualties or fatalities to the surrounding public. This is something for us to consider in order to build our national capacity and preparedness to manage any suspected or actual CBRNe incident in the future.
Conclusion
The case of the homicide of a North Korean with nerve agent has shown the possibility and potential for chemical weapons to be used in terrorism. There are few publications and documented cases of the use of VX on a human. The metabolism of VX in the human body is still unclear. Besides nerve agents, there are actually other simple yet conventional chemicals in common industrial use that can also become potential chemical weapons. The statement by the World Health Assembly in May 1967 that “scientific achievements, and particularly in the field of biology and medicine – the most humane science – should be only be used for mankind’s benefit, but never to do it any harm” remains as valid today as it was then. One can hope that the OPCW and the Chemical Weapons Convention can remain strong to uphold the international treaty in order to prevent non-conventional weapon attacks resulting in mass-casualty incidents.
About the Author
Lay See Khoo is a senior Forensic Scientist who has been working for the National Institute of Forensic Medicine under Ministry of Health Malaysia for more than 15 years. She is currently a Member of Panel Evaluator in the field of Forensic Science for the Malaysia Qualifications Agency (MQA) appointed by Chief Executive Officer MQA since 2017, as well as a Permanent Representative for the Forensic Sciences Technical Committee to develop the Malaysian Standards appointed by the Director of Standards Development Agency, Malaysian Institute of Chemistry (IKM) since 2016.
