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Radioactivity in
Foods Grown on Mined Phosphate Lands
Jerome J. Guidry, P.E.
Post, Buckley, Schuh & Jernigan, Inc.
1990
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A significant amount of reclaimed mined land is used for
agriculture and questions about how the radiation associated
with phosphate impacts the food grown on the land makes this
and other FIPR-related work important. In order to ensure
that its radiation research program is comprehensive, the
Institute has devoted much attention to the human food chain.
FIPR's studies on crops and animals on mined lands have found
that the radionuclides in crops grown on mined land are slightly
higher than on unmined land, but that the total quantities
were small even under a worst-case scenario.
This study grew a broad range of crops, including crops that
would not normally be grown in Florida. It then evaluated
the dose to a hypothetical person who obtains all of the foods
sampled in this study from reclaimed clay lands and the remainder
of his diet from the general food pool. It showed that if
a person took every crop grown off this land and made it part
of his or her daily diet, the dose of radionuclides the person
would get from eating the food would be quite low and is not
considered to be a health hazard.
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Florida Statewide
Radiation Study
GEOMET Technologies, Inc.
1987
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It
is commonly known that Central Florida phosphate contains higher
levels of uranium than other soils, but this did not become
a subject of wide interest until the mid-1970's when it was
found that some homes built in uranium mining areas of the Rocky
Mountains had higher than desirable indoor radiation levels.
At that time, both the U.S. Environmental Protection Agency
(EPA) and the Florida Department of Health and Rehabilitative
Services performed limited surveys of indoor radiation in homes
built in the central Florida phosphate district. Both studies
showed that some persons in the area were exposed to levels
of radioactivity significantly higher than normal background
levels.
In May of 1979 the Administrator of EPA wrote to the Governor
of Florida, suggesting that remedial action was necessary
in some existing homes, and that future new homes built in
the region should incorporate construction techniques to resist
the entry of radon gas. At that point, the Governor appointed
a Task Force to consider the problem and the result was the
development of a standard for indoor exposure of citizens
to naturally occurring radioactive materials, mainly the decay
products of radon gas.
Controversy quickly arose, however, over what lands in the
state would be affected. The State Office of Radiation Control
proposed to apply the new rule only in areas of reclaimed
phosphate lands, mostly in Polk and Hillsborough counties.
Many persons objected to this, feeling that other parts of
the state as yet unidentified very probably had areas of elevated
radon levels and should be included under the rule. As a result
of this, the 1986 Legislature, in the closing days of its
session, mandated the Florida Institute of Phosphate Research
to direct a study of the entire state to identify all significant
land areas of Florida where the rule should be applied.
The study confirmed that while radon was related to the prevalence
of phosphate in the ground, levels were generally lower than
those found in most other parts of the country. Also, it was
determined that radon was not a problem solely on reclaimed
lands; homes with elevated radon were found from north Florida
to southeast Florida.
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Environmental Monitoring
of Polk and Columbia Counties Experimental Phosphogypsum Roads
Gordon D. Nifong and Jon K. Harris
Florida Institute of Phosphate Research
1993
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Those
watching the Florida Department of Environmental Protection
(DEP) struggle to drain the acidic process water ponds on top
of an abandoned phosphogypsum stack at Piney Point in Manatee
County are asking if the phosphogypsum the phosphate industry
produces each year can be used instead of stacked. The answer
is yes, but the US Environmental Protection Agency (EPA) has
banned the use of phosphogypsum due to its low level of radioactivity.
One of the most promising uses for phosphogypsum would be as
a road-building material.
This study took a long-term look at roads built during a
previous FIPR study, which showed the phosphogypsum was a
suitable building material from an engineering standpoint
and that environmental effects of the gypsum on the local
environment, especially groundwater, were minimal. The question
was asked as to whether there might be any long-term trends
in environmental quality as a result of the gypsum's use.
Thus the Institute continued for an additional 2½ years
the environmental monitoring. Results indicated that long-term
effects on the local environment from phosphogypsum use in
roads are minimal.
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Evaluation of Exposure
to Technologically Enhanced Naturally Occurring Radioactive
Materials (TENORM) in the Phosphate Industry
Brian K. Birky, Thabet Tolaymat, & Bernhardt C. Warren,
Applied Environmental Consulting, Inc.; W. Emmett Bolch, Environmental
Radiation Group; Robert Ammons, Thomas McNally, J. Wesley
Nall, Polk County Public Health Unit
1998
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In 1994, federal rules for the acceptable dose of natural
radiation for members of the public dropped from 500 millirem
(mrem)/year to 100 mrem/year. As a result, Florida's Department
of Health and Rehabilitative Services Office of Radiation
Control asked FIPR to assess if state natural radiation exposure
guidelines for the phosphate industry needed to be changed
for employees or service contractors exposed to slightly elevated
radiation, but not trained as radiation workers.
This project updated 15-year-old data and found that most
phosphate industry employees encountering radiation are trained
and thus are subject to the occupational exposure limit of
5000 mrem/year, which they would be "highly unlikely"
to approach or exceed. The study did note that the badges
now used to monitor external radiation exposure are not sensitive
enough to pick up the dose because it is so low. It also recommended
considering controls and use of respirators in areas where
there is airborne dust or mist.
Workers for subcontractors specializing in cleaning and refurbishing
plant equipment may also receive increased doses, but are
often not trained in radiation safety and thus are subject
to public dose limits. The doses received, however, are far
below the 100 mrem/year limit, according to the report. The
exception was attack tank cleaning workers and the report
recommended a targeted study to clarify dose in this area.
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