A World War II-era contamination suit. (Credit: Shutterstock) In January 1958, two medical officers at Porton Down, Britain’s military science facility, exposed their forearms to 50-microgram droplets of a substance called VX, which was a new, fast-acting nerve agent that could kill by seeping through the skin. VX, short for “venomous agent X,” is tasteless, odorless and causes uncontrollable muscle contractions that eventually stop a person’s breathing within minutes. That experiment in 1958, according to University of Kent historian Ulf Schmidt, was perhaps the first human test of VX in the Western world. Though VX is outlawed under the 1997 Chemical Weapons Convention, it was used to kill North Korean leader Kim Jong-un’s half-brother, Kim Jong-nam, in Malaysia last week. North Korea maintains the third largest stockpile of chemical weapons, trailing only the United States and Russia, according to the Nuclear Threat Initiative project. As such, South Korea has pinned blame for the attack on the North Korean government, and the use of a banned weapon may increase pressure on the international community to formulate a response. Given these recent developments, it shouldn't come as a surprise that this lethal chemical agent has a checkered, infamous past. In the mid-1990s, the Japanese cult Aum Shinrikyo used VX in attempts to kill three people—one was successful. In 1969, the U.S. Army admitted that VX was responsible for the deaths of 6,000 sheep in Utah. But VX was trouble from the very start. You see, that first first-of-its-kind human trial in 1958 at Porton Down was actually an unauthorized experiment conducted in shadows, as Schmidt revealed in his 2015 book “Secret Science”.