Treatise on Poisons by Sir Robert Christison
7. _Habit and Idiosyncrasy._—The remarks to be made under the present
1266 words | Chapter 12
head are important in a medico-legal point of view: for they show how
one man may be poisoned by a substance generally harmless, and another
not harmed by a substance usually poisonous.
The tendency of _idiosyncrasy_ is generally to increase the activity of
poisons, or even to render some substances deleterious which are
commonly harmless.
The effect of opium in medicinal doses is commonly pleasant and
salutary; but in some individuals it produces disagreeable and even
dangerous effects. Calomel, which in moderate doses is for the most part
a mild laxative or sialagogue, will cause in some people, even in the
dose of a few grains, violent salivation, ulceration of the mouth, nay,
fatal gangrene. On the other hand, a few substances, which to most
people are actively poisonous, have on some individuals comparatively
little effect. There are extremely few poisons, however, in regard to
which this kind of idiosyncrasy is well established and prominent.
Mercury and alcohol are examples. The compounds of mercury, which in
moderate quantity are mildly laxative or sialagogue to most people, but
to some persons dangerously poisonous in very small doses, would, on the
contrary, appear in other constitutions to be extremely inactive; for it
has occasionally been found impossible to bring on the peculiar
constitutional action of mercury by continuing the use of its
preparations for months together. In general children are not easily
affected by calomel as a sialagogue, but easily by its laxative action.
As to alcohol, it is a familiar fact, that independently of the effects
of habit, there are some constitutions which cannot be brought under the
influence of intoxicating liquors without an extraordinary quantity of
them and a long-continued debauch, while others are overpowered in a
short space of time, and by very moderate excess; and there is no reason
to doubt that very great constitutional differences also prevail in
regard to the operation of a single large dose. A rarer idiosyncrasy is
unusual insensibility to the action of opium. I am acquainted with a
gentleman unaccustomed to the use of opium who has taken without injury
nearly an ounce of good laudanum,—a dose which would certainly prove
fatal to most people.
But not only does idiosyncrasy modify the action of poisons: Through its
means, too, some substances are actually poisonous to certain
individuals, which to mankind in general are unhurtful, nay, even
nutritive.
With some people all kinds of red fish, trout, salmon, and even the
richer white fish, herring, mackerel, turbot, or holibut, disagree as it
is called—that is, act after the manner of poisons: They produce
fainting, sickness, pain of the stomach; and if they were not speedily
evacuated by vomiting, dangerous consequences might ensue. The same is
often the case with mushrooms. The esculent mushrooms act on some people
nearly in the same way as the poisonous varieties. Bitter almonds and
other vegetable substances that contain hydrocyanic acid, sometimes
produce stupor or nettle-rash in the small quantities used for seasoning
food. In like manner many flowers, which to most persons are agreeable
and not injurious, cannot be kept in the same room with some people on
account of the severe nervous affections that are developed.
This idiosyncrasy may even be acquired. One of my relations, who was for
many years violently affected by very small quantities of the richer
kinds of fish, used at a previous period to eat them, and can now again
do so, with impunity. Many people have acquired a similar idiosyncrasy
with respect to eggs; instances of the same kind will be afterwards
mentioned in respect to shell-fish, particularly muscles; indeed there
are probably few articles of food in regard to which such idiosyncrasies
may not in a few rare instances be met with, if we except the grains and
common kinds of butcher-meat. I may add, that from facts which have come
under my notice, I have sometimes suspected that a similar idiosyncrasy
may be acquired in a slight degree, and for a short time only, in regard
even to some kinds of butcher-meat, especially the flesh of young
animals and pork. On this subject some illustrations will be found at
the close of the chapter on diseased and decayed animal matter.
It does not appear well ascertained, that the effect of idiosyncrasy is
ever to impair materially the energy of poisons, except in the instances
of mercury, alcohol, and opium.
On the contrary, the tendency of _habit_ when it does affect their
energy, is, with a few exceptions, to lessen it. By the force of habit a
person may take without immediate harm such enormous quantities of some
poisons as would infallibly kill an unpractised person or himself when
he began. There have been opium-eaters in this country who took for days
together ten or even seventeen ounces of laudanum daily.
The influence of habit has been ascertained precisely in the case of a
few common poisons only. On the whole, it would appear that more change
is effected by habit in the action of the organic than in that of the
inorganic poisons; and that of the former, those which act on the brain
and nervous system, and produce _narcotism_, are altered in the most
eminent degree. The best examples of the influence of habit are opium
and vinous spirits. The action of such poisons is not always, however,
entirely thrown away; they still produce some immediate effect; and
farther, by being frequently taken, they may slowly bring on certain
disease, or engender a predisposition to disease. A very singular
exception to this rule prevails in the instance of tobacco; which, under
the influence of habit, may be smoked daily to a considerable amount,
and, so far as yet appears, without any cumulative effect on the
constitution, like that of opium-eating or drinking spirits.
The inorganic poisons are most of them little impaired in activity by
the force of habit. The pure irritants, indeed, do lose a little of
their energy: for it seems that persons have acquired the power of
swallowing with impunity considerable doses of the mineral acids. But as
to inorganic poisons that enter the blood, habit certainly does not
diminish, probably rather increases, their power. There is no
satisfactory evidence, that a person by taking gradually-increasing
doses of arsenic may acquire the power of enduring a considerably larger
dose than when he began: On the contrary, the stomach rather becomes
more tender to the subsequent dose by each repetition. I have little
hesitation in avowing my disbelief of the alleged cases of
arsenic-eaters and corrosive-sublimate-eaters, who could swallow whole
drachms at once with impunity. Some have expressed surprise at this
statement having been made in former editions of the present work, when
there is such authority as Byron, Pouqueville, &c., for the hackneyed
story of Soleyman, the sublimate-eater of Constantinople, who lived to
the age of a hundred, eating a drachm of corrosive sublimate daily. I
must avow, however, that such reporters of a feat so very extraordinary,
and where deception was so highly probable, are to me no authority at
all.
In the relative influence of habit on poisons of the three kingdoms of
nature, a new argument will be discovered for the opinion given above
respecting the partial decomposition of organic poisons in some of the
tissues. In fact this partial decomposition accounts very well for the
effect of habit: The effect of habit is probably nothing more than an
increased power acquired by the stomach of decomposing the poison,—just
as it gradually acquires an increased facility in digesting some
alimentary substances which are at first very indigestible.
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