Is it true that a drop of nicotine kills a horse?

When talking about the dangers of smoking, they often say that even a minimal amount of nicotine can lead to the death of a large ungulate, let alone a human. We checked how valid this expression is.

In Russian-language popular culture, among all the arguments in favor of quitting smoking, this one has become entrenched: “One drop of nicotine kills a horse.” Whether the call is effective or not is a separate question, but Viktor Dragunsky mentions this phrase in the book of the same name text from the series “Deniska’s Stories”, and Alexander Zhitinsky plays on the anti-tobacco warning in story "Drops". In post-Soviet culture, very short forms appeared - memes and jokes like “A drop of nicotine kills a horse, and a cup of coffee kills the keyboard.” But the expression is still used for its original purpose - for example, Yakut doctors paint thus the danger of cigarettes.

Within a few decades after the discovery of tobacco, Europeans began to use animals for research on the dangers of nicotine. At first, cats and dogs became victims of science, but in 1864, chemist August Kuhlmann conducted an experiment on a horse. He described his observations in his dissertation “On the influence of tobacco on the body”: “If you introduce a few drops of nicotine into the mucous membrane of a horse’s nose and mouth... the animal immediately begins to worry, looks around and tries to run away, but cannot take a single step; breathing accelerates, becomes difficult and audible; soon the animal begins to tremble... the body becomes covered with cold, sticky sweat, the trembling is accompanied by tremors, the horse begins to stumble... and finally falls, stretched out, to the ground, where it soon expires.”

Apparently, the formulation in which several drops turn into one first appeared in 1879. French physician Hippolyte Depierre published a text for children claiming that “one particle” of nicotine would kill a horse when injected into the body, and one drop would kill a horse when put into the eye. However, Depierre was an active opponent of smoking, and the text did not pretend to be scientific, so the above calculations are questionable. In the domestic publications that have reached us, “one drop” is mentioned only in relation to dogs or simply “animals” until the end of the 1950s, and the statement we verified was not used even on numerous posters warning Soviet citizens against smoking. Historian and cultural scientist Konstantin Dushenko assumesthat the formulation “a drop of nicotine kills a horse” appeared in the late Soviet years under the influence of numerous popular science publications and was finally entrenched in popular culture already during the years of perestroika. By the way, two decades earlier, a similar process occurred in Poland.

How much nicotine does it really take to kill a horse? In 1994, a group of American veterinarians published scientific article, which presented data on the death of mules due to nicotine poisoning. Although the scientists do not mention the source they cite, they do cite a dosage of 100–300 mg as lethal for an adult horse. Back in 1958 in a reputable magazine Science were published results In a more relevant experiment, scientists injected nicotine into the muscles of different animals and calculated the maximum possible dose. It turned out that horses, cats, deer and cattle are much more susceptible to the negative effects of nicotine than goats, dogs, rats and even rabbits. According to scientists' calculations, the lethal dose for horses is 8.8 mg per kilogram of weight.

Although the drop is not a standardized unit of measurement, it is quite possible to make a rough calculation. From the point of view medicine a drop is approximately 0.05 ml. Considering that the density of water and nicotine is almost the same and equal to one, the volume of a drop of nicotine is also about 0.05 ml, and the weight is 0.05 g. Horses weigh from 400 kg - accordingly, to kill an adult animal, according to American veterinarians, you will need at least 3.5 g of nicotine, or 70 drops.

Fake

What do our verdicts mean?

Read on topic:

1. K. Dushenko. A Drop of Nicotine Kills a Horse: The Story of a Mysterious Poster
2. https://science.sciencemag.org/content/127/3305/1054