Pet tear UE Uses O Nev -U. Ur lak. TO TIN 25 
‘OVERLOOKED’ SOURCES OF MERCURY POLLUTION 
TO BE ASSESSED BY CARSON TRUST 
fhe Rachel Carson Trust for the Living Environment, Inc., has issued a 
lea among U.S. scientists, conservationists, and appropriate publications 
er information on scurces of mercury contamination which, the Trust says, 
ias been “overlooked” in the recent mercury-pollution reports. 
For many years, mercury in various forms has been a standard material 
ised in hospitals, medical and cther laboratories for making slides in his- 
ological, pathological, cytological and other procedures. (Until recently, 
t was generally used as a disinfectant, and in various forms of therapy. 
“hough these uses have been largely superseded, they may still be pre- 
‘alent in some institutions.) 
Most mercury so used eventually goes down the drain, to add to the 
yuurden in water and in stream and lake bed accumulations from which 
t is absorbed by fish and other aquatic life. It is an absolutely permanent 
ubstance, and can remain in such deposits for as much as 100 years, 
entinuing to poison acquatic life and anything that feeds on it. Less toxic 
orms once released into the environment may change to highly toxic 
aethyl mercury. 
As far as the Rachel Carson Trust has been able to determine, little 
x no attention to this source of pcllution has been given by the institutions 
oncerned. The amounts released so far can only be determined by a 
iainstaking search of purchasing records and a review of methods of use 
ver past years. Some downstream assays should also be made to help 
udge the amounts that have been released in our environment by this 
aeans. While not comparable in magnitude to mercury use in agriculture 
nd industry, it is one source that can readily be stopped. 
As one example, a small hospital with average histological procedures 
as been using 150 pounds a year. 
Among professions listed as especially liable to mercury pcisoning 
re dentists and medical laboratory technicians; moreover, there seems to 
ave been little awareness in these professions that another byproduct of 
4eir use of mercury would be the contamination of everything downstream 
rom their laboratory drains by this insidious, highly toxic, and absolutely 
ermanent metal. 
Dr. Clarence Tarzwell, a director of the Trust, first brought to attention 
his use of mercury in hospitals and laboratories as a possibly significant 
ource of contamination. 
“We have tried within our limited resources to determine the extent 
f the problem in some typical situations. We have thus welcomed the 
‘ongressional attention focused on mercury, first on April 21, 1970 by 
‘ongressman David Obey, and later by Senator Hart in his hearings on 
dis and other metallic contaminants. We hope that with public interest 
1 this matter aroused, others will undertake to find out what mercury is 
sed in their own communities, and will exert all possible pressure for 
afer procedures. Mercury is not essential for any of these laboratcry 
rocesses.” 
Doubts have been raised about the practice of filling teeth with amal- 
am — a mixture of mercury and silver. This practice is apparently the 
hief reason for mercury poisoning among dentists, but no one is certain 
