Search of Epidemiologic Guides

Y12.1302
Workplace Hygiene and Worker Health
An area of interest of the Mercury Task Force was the impact of mercury toxicity
on workplace hygiene and worker health. From the beginning of the lithium
isotope separation and enrichment process at Oak Ridge, AEC officials and Y-12
Plant managers and industrial hygienists recognized the need to safeguard and
monitor the health of the workforce. From 1950 to 1954, industrial hygiene
programs were instituted in the Orex, Elex, and Colex pilot plants. With the
industrial scale use of mercury in the Colex operations after 1954, these
officials became especially concerned about the medically recognized hazards of
inhaling toxic mercury vapor. Since greater quantities of mercury would be used
in full-scale Colex operations than previously, the plant expanded existing
industrial hygiene programs and implemented new ones to protect worker health.

The Colex process was a pioneering technology that required specialized pumps,
valves, and other equipment not used previously for such applications. Plant
engineers anticipated frequent maintenance and operational problems during the
initial months of operation. In 1955, the first full-scale year of the Colex
process, the pumps and valves required much service and repair. Often the
processing system was full of mercury and large quantities of it leaked and
spilled on the floor. Drainage systems were modified so that the floor drains
would direct the mercury into special tanks that separated the mercury from
wastewater, mainly mopwater, collected in sumps that emptied into the creek.

From the outset of the Colex operations in 1953, Y-12 conducted both routine air
sampling to monitor the mercury concentrations within the workplace and a
urinalysis program to monitor individual worker exposure. During the start-up of
Colex operations in 1955, air sampling indicated that mercury concentrations in
Buildings 9201-4 and 9201-5 were higher than the then recommended standard of
0.1 milligram/cubic meter (now 0.5 mg/m3). Urinalysis also indicated that
workers had been exposed to higher concentrations of mercury than normal in
1955. In general, the risk of mercury exposure was greatest in 1955 and 1956,
the ramp-up years of Colex operations. After 1956, the risk declined as air
sampling data indicated mercury concentrations below the threshold limit value
of 0.1 mg/m3.

In addition to the air sampling and urinalysis programs, Y-12 conducted a
special medical surveillance program of the Colex workforce. Workers were
medically examined every six months and workers with a history of albuminuria,
kidney problems, or hypertension were screened out and not assigned to work in
mercury exposed areas.

In late 1955, AEC and Y-12 managers instituted various mechanisms to reduce
mercury concentrations in the workplace and safeguard worker health. The plant
studied paints and other substances that could reduce vapor pressure and
dissolve mercury droplets. Large fans were installed at the ends of the process
buildings to remove contaminated air and circulate fresh air throughout the
production areas. A special vacuum system was installed for mercury removal. In
early 1956, the plant emphasized the use of respirators and, after a close
examination of the commercially available respirator filter cartridges, selected
the Mersorb cartridge for use by Colex workers. The effectiveness of these and
other measures is documented in the historical record of air concentrations,
which shows significant reduction of mercury concentrations in the air by March
1956 and successful control of mercury release during the subsequent operating
years.



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