Scottish Daily Mail

Killers, what’s your poison?

- Compiled by Charles Legge

QUESTION What is considered to be the most poisonous substance produced in the natural world? BOTULINUM toxins are a group of neurotoxin­s produced by the bacterium Clostridiu­m botulinum. There are seven forms of Botulinum toxins (labelled as types A,B, C [C1, C2], D, E, F and G). Types A, B and E are associated with systemic botulism in people.

The toxins disrupt communicat­ion between nerves and muscle cells, gradually paralysing the victim and causing respirator­y failure. According to one paper, Botulinum Toxin As A Biological Weapon (Journal of the American Medical Associatio­n, 2001): ‘A single gram of crystallin­e toxin, dispersed and inhaled, would kill more than 1,000,000 people.’

An unusual feature of Botulinum toxins is their exquisite selectivit­y of human body cells; thus Botulinum toxin, as used in Botox injections, is safe.

Perhaps, therefore, a more lethal poison is ricin, found in that popular ornamental shrub, the castor oil plant. The relative ease of extracting the toxin from castor beans has made it the poison of choice for many assassins, including the one who, via an umbrella, fired a tiny pellet containing ricin into a Bulgarian dissident’s leg in London in 1978, killing him.

Ricin produces proteins that destroy ribosomes, the cell’s protein builders, and there is no antidote once it is in the bloodstrea­m. One-thousandth of a gram would be lethal in an injection; about 0.1g i f eaten. similar chemicals can also be extracted from the elder and mistletoe.

The most potent toxin produced by an animal is tetrodotox­in, a neurotoxin in the gonads, liver, intestines and skin of fugu, a type of pufferfish. One-hundredth of a gram is considered a lethal dose.

Fugu is a delicacy in Japan and has to be cooked in a certain way to render the toxin harmless. Although chefs need a licence to serve fugu, about 200 people a year are still poisoned by it, half of them fatally.

Dr Ian Smith, Cambridge. QUESTION Why is the girl’s name Vanessa used to classify butterflie­s? For example a red admiral is Vanessa Indica. Further to the earlier answer, the name Vanessa Indica actually refers to the Indian Red Admiral. This is different from our familiar, Red Admiral, whose Latin name is Vanessa Atalanta.

The Red Admiral was previously known here variously as: the Admirable, the scarlet Admiral and the Alderman.

Tim Boone, Worthing, West Sussex.

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