Document M46Rgy9yKapYDwn0odbEyjMZM
December 23 1933
^r. Ray Bevan Abford House, Victoria
London B.W. 1
Dear Ray*
I hasten to write to you with regard to the opinions of Dp, Kohn-Abrest and point out to you the extent to which his questions have been answered in our experimental work. I have no illusions as to the effect which one may expect to achieve In making reply.
According to his writings he is an opinionated person,
and in this instance 1 suspect that he has an ax to
grind.
The facts are these*
(1) The study of the distribution of lead in exper imental animals after the absorption of tetraethyl lead (refer to able 7 In article The Behavior of Lead in the Animal Organism XI Tetraethyl Lead) show that aside from the lead absorbed into the skin at the site of application comparatively insignificant amounts of lead occur in the skin and hair.
(2) rQje distribution of lead in animals after the
absorption of inorganic lead compounds does not favor the skin to any appreciable extent. (Bee Table X of the enclosed article in the Journal of Laboratory and Clinical Medicine, November 1933* ^his is just out.
1111 send reprints as soon as X get them. J
(3) The examination of the hair in leaded animals.
(Bee especially Table I in article "The Behavior of
Lead in the Animal Organism I in American Journal of
Public Health, &ay 1928) fails to show significant
amounts of lead.
,
Uj.) The teeth of animals and human beings, oh which we have consiqerat>l amounts of unpublished data, shoe the same sort of affinity for lead that is shown by other bony tissues i.e. the skeleton.
(3) The excretion of lead from the skin, hair and teeth
is obviously insignificant with the above facts in mind. Xn furry animals any loss of lead from the body by way of the hair is due to the shedding of hair. On the other hand examination of the hair is fraught with large
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possibilities for error by reason of surface contamina
tion through contact with faeces, urine, and other lend
in the environment, ^hus the data showing the presence
of considerable amounts of lead in the hair are questionable
excepting as the most minute attention has been given to
cleansing before analysis. In human beings the hairy
surfaces are small In area and are thus insignificant
as a source of lead loss through shedding of hair. The*
teeth, obviously, do not give up their lead except by ;
way of the circulation. *hey may, of course, be ex- *
tracted, thereby removing small amounts of lead from ; '
the body.
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(6) Observations on the fate of lead in the tissuesj \
made very carefully and described In the articles cited
above, show that the alimentary and urinary excretion
account for practically the total lead interchange in
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the body,
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(7) Observations on human lead metabolism described In our studies recently published In the Journal of
Industrial Hygiene show, similarly, that the loss of lead from the body Is chiefly by way of the alimentary tract, and to a lesser extent by way of the kidneys, both under conditions of normal absorption and also during lead intoxication.
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The figures given by Kohn-Abrest sound strangely |;`
familiar. They closely resemble those of Melllere pub- j
lished in 1903, and one may suspect thet that Is their
'
source. Unfortunately Melliere did not analyze the
skeleton, or if he did failed to recognize the lead present
there, Thue he missed an important point. It Is true
that the skin practically always contains lead, and some- ;
times In higher concentration than that in the liver, but :
never to the extent seen in the bones. Thus the chief
source of lead for excretion, after exposure has been ended I
is found In the bones. It is ridiculous, therefore, to
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regard the skin as a relatively Important tissue for lead i
storage and lead excretion. However, the question whether
or not measureable amounts of lead are excreted by the
skin - and an adequate study of the subject of lead ex-
cretlon by the skin, by way of falling hair and perspiration
presents peculiarly difficult problems because of the factor ;
of external contamination - becomes an academic problem,
purely, when the significance of our study of the relation- :
ship between lead absorption and lead excretion In the faeces |
and urine, is appreciated. *n studying the various avenues V
of lead excretion and their relationship to lead absorption, '
in the problem of leaded gasoline, we are Interested primarily,
in one question, viz, - does lead absorption occur to a
significant degree tinder the conditions of exposure to leaded
gasoline? hat question has been answered by showing (l) that
faecal and urinary excretion are increased by even minute
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increases In lead absorption* (2) that no such increase in lead excretion appears on exposure to leaded gasoline.
One wonders, in relation to the pronounced activity of the hair mentioned by Kohn-Abreat If he is not confusing lead with arsenic.
One wonders, still more, if he is not creating a fictitious problem in order to obtain funds for an equally fictitious investigation, however, be that as it may, the questions proposed are not worthy of being dignifled by a too serious consideration.
You are at liberty to use the facts in the above discussion as you wish* I would suggest, though it is un necessary to do so, in your case, that they shew. Id not be used to instigate or keep alive a futile controversy.
In concluding this long letter, I wish to mention a more important matter, and to wish you the happiest Christmas and Kew Year* It would be a pleasure to see you in person and to express my good wishes directly. Howevor, I do express them and none the less heartily through this medium.
Sincerely,
RAK;IS
Robert A, Kehoe, i.-C.
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