Tuesday 10 November 2015

Cup of death

Cup of death: mortality by the mass was the title of a fifteen minute talk given His Blobbiness yesterday at the 11am coffee break as his contribution to Science Week. If you live in Irealnd, you are exhorted to find out what's happening locally for Science Week and go down to double the audience for some poor boffin trying to explain his stuff to Joe Public. If you live elsewhere, find out when Science Week is held and do likewise. We scientists are notoriously inept in doing public engagement and lay summaries of research. My talk wrote itself because I've written almost all the chapters before including a table showing just how much of substance X does it take to kill one person. Interestingly, the killing-dose varies, according to substance, through 18 orders of magnitude. To put that in scale: if the smallest dose was 1 gram [about 1 cu.cm for many biological substances] then the largest requires a mass equivalent to the island of Ireland, Portugal or Indiana dug out to a depth of 10 km.  I'll lash up a summary table here and then append some notes.
Kill dose Substance Mol.Wt. No. dead Date
150 ng Botox 150,000 Da None? NA
150 µg Ricin 64,000 Da One 07 Sep 1978
150 mg Sarin 140 Da 300-2000 21 Aug 2013
150 g Cricket ball NA 2 07 Jul 2015
150 Kg Propylene 42 Da 220 11 Jul 1978
150 Ton Beer 18+ Da 16 14 Oct 1814
150 Ton Crude Oil 50-500 Da? 37 05 Jul 2013
150 Ton CO2 44 Da 1700 21 Aug 1986
150 Kiloton Water 18 Da 16 02 Nov 1925
  • It is perhaps notable that the most efficient killers are enzymes. Tweaked and polished by evolution to carry out a biochemical task really really fast, they outstrip man-made chemical processes doing the same thing.  That's why we use them in food and fermentation.
  • Botox is a cocktail of toxins produced by Clostridium botulinum: it prevents vesicles full of neurotransmitter acetylcholine from leaving neurons at the neuromuscular junction: resulting in a flaccid paralysis.  Its near relative Clostridium tetani makes a toxin, whose lethal dose is about 2x that of Botox, which prevents the secretion of the "anti-acetylcholine" neurotransmitter GABA: giving a spastic/tetanic paralysis. You have anti-tetanus injections if you have a deep and dirty cut, in order to mop up any tetanus toxin that's getting produced.
  • Ricin is not so toxic as Polonium which was used to terminate Russian dissident Alexander Litvinenko Алекса́ндр Ва́льтерович Литвине́нко he was given a lethal dose of Polonium: like Georgi "Ricin" Markov the assassination was carried out in London.
  • Cricket ball is about the same size and weight as a baseball or a sliotar. There was a famous 2014 case in Australia when Phillip Hughes taking a tonk from one of these missiles on the side of his [helmetted] head.  It was captured on TV.  The more recent date notes the death of Bavalan Pathmanathan in England who died after a cricket-ball blow to the chest.
  • 150 tons is gratifyingly diverse in the variety of materials that will kill you. You might think that 'waking up dead' from CO2 poisoning would be a better way to go than burning to death in an oil BLEVE.  But dying of carbon dioxide is rough enough; and only a stage Irishman would think that dhrowning in dhrink was dignified or pleasant.
  • Molasses is sweeter, stickier and less lethal than beer - 400 tons per person sharing.
  • I picked one particular dam-burst because the numbers fitted best with my go-up-by-1000x narrative.  Vajont was much more efficient but also absolutely more lethal [dead = 2000].  And of course a few litres of water can drown a baby in a bath-tub.
I'm glad I was able to fill in the gap in the series with the cricket ball. It wraps up this long-running obsession with patterns of death. I promise I'll give it a rest, unless you come to Wexford Science Cafe next Tuesday - you'll have to bind and gag me there.  I've printed some pictures and they need another outing.

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