Bryce-Smith, D.  "Mercury fillings" [letter].
CHEMICAL AND ENGINEERING NEWS,
49(6): 8, 61  (2/8/71).


SIRS:  Your correspondent F. J. Kirkish who
has enquired about a possible
hazard from the silver-mercury amalgam used in
dental fillings (C&EN, Nov.
23, 1970, page 7) may like to note the report
by T. A. Cook and P. O. Yates
[BRIT. DENT. J., 127:553 (1969)] of the death
through mercury poisoning of
a dental surgery assistant who had been
handling dental amalgam containing
40% mercury during the 20 years of her
occupation.  Analysis of her kidneys
by neutron activation analysis showed the
presence of 520 p.p.m. of mercury.
In comparison, the kidneys of three patients
thought to have had no abnormal
contact with mercury contained 2, 5, and 9
p.p.m. of mercury.

Although mercury may be concentrated to some
extent in the kidneys, these
figures for mercury in "normal" kidneys are
high in comparison with levels
considered unacceptable in tuna fish and other
foodstuffs.  They provide
evidence that mercury from the environment is
already accumulating in the
tissues, even those of persons who are not
using mercury in the course of
their occupation.

On the facts available, it seems that there
is urgent need for an impartial
scrutiny of all sources, including dental
amalgam, from which mercury might
enter body fluids and soft tissues.

It should also be borne in mind that mercury
is chemically rather similar
to lead, another environmental pollutant which
like mercury tends to damage
the central nervous system, and to which
children can be even more sensitive
than adults.  Indeed, any realistic assessment
of the degree to which the
central nervous system is at risk should
probably also consider the integ-
rated effects of all other environmental
pollutants, including certain pest-
icides, to which the nervous system in many is
known to be sensitive.  I am
not aware of any evidence that health
authorities yet base their safety
criteria on such comprehensive considerations.



D. Bryce-Smith, D.Sc.

Department of Chemistry,

The University,

Reading, England