Alfalfa and a number of foodstuffs including milk, asparagus, wheat, beef, chickens, eggs, vegetables, fruits, and wine were collected at several locations surrounding the Hanford Site (Figure 5.4.1). Samples were collected primarily from locations in the prevailing downwind directions (south and east of the Site) where airborne effluents from Hanford could be expected to be deposited. Samples were also collected in generally upwind directions, on the Site perimeter and at locations somewhat distant from the Site, to provide information on background radioactivity. This section summarizes the radiological analyses performed on samples collected in 1994. Detailed analytical results are listed by Bisping (1995), some of which have been summarized in Appendix A. The potential dose to members of the public from consuming local foods and farm products is addressed in Section 6.0, "Potential Radiation Doses from 1994 Hanford Operations." Results for fruits and vegetables and animal products are reported in pCi/g wet weight. Results for wheat and alfalfa are reported in pCi/g dry weight. Radionuclide concentrations in most samples were less than the limits of detection. Results for tritium (tritium present as water) in milk, wine, and fruits are reported in pCi per liter (pCi/L) of liquid distilled from the food product. Most tritium is found as water, and very little tritium is organically bound to other constituents present in biological material.
The food and farm product sampling design addresses the potential influence of Hanford Site releases in two ways: by comparing results from several downwind locations to those from generally upwind or distant locations, and by comparing results from locations irrigated with Columbia River water withdrawn downstream from Hanford to results from locations irrigated with water from other sources. Specific details of the sampling design including sampling locations and radionuclides analyzed are reported by Bisping (1995) and DOE (1991b) and are summarized in Table 5.4.1. Gamma scans (cesium-137, cobalt-60, and other radionuclides; see Appendix F) and strontium-90 analyses were routinely performed for nearly all products. Selected food products were specifically analyzed for additional radionuclides including iodine-129, plutonium, technetium-99, tritium, and uranium.
One uncontrolled factor influencing concentrations of radionuclides in milk and other dairy products, beef, and poultry is the source of food for the farm animals. Cattle and poultry may be fed with food grown outside of their sampling locations. For radionuclides that are present in fallout from weapons testing, fallout radioactivity in feed may be a significant source of monitored levels in dairy products. Generally, levels of fallout radioactivity in environmental media correlate positively with precipitation.
Milk was analyzed for iodine-129, strontium-90, tritium, and gamma emitters such as cesium-137 because these radionuclides have the potential to move through the air-pasture-cow-milk or water-pasture-cow-milk food chain. Tritium is released into the atmosphere from Site facilities and to the Columbia River via shoreline ground-water springs. Strontium-90 is released into the Columbia River through the N Springs. Iodine-129 has been released to the air from the Hanford Site in the past and is still being released to the Columbia River via the Site ground-water plume. Cesium-137 was present in atmospheric fallout from weapons testing and is found in Site radiological waste. Tritium and gamma analyses were conducted on each monthly
sample, strontium-90 analyses were conducted on
each quarterly sample, and iodine-129 analyses
were conducted on two semiannual composite
samples (one each from Sagemoor and Sunnyside).
Tritium analysis was performed on water distilled
from milk, and as a consequence, would slightly
overestimate the true concentration of tritium in
bulk milk.
in a sample collected from the
Sagemoor area. While there is no tritium standard
for milk, the standard for drinking water is 20,000
pCi/L.
Strontium-90 was measured in six of nine (67%)
milk samples analyzed in 1994, with no apparent
differences between upwind and downwind
locations (Table 5.4.2). Concentrations of
strontium-90 have remained near the detection limit
(4 pCi/L) and relatively constant over the past 6
years (Figure 5.4.2). The maximum observed
concentration of strontium-90 in milk in 1994 was
. While there is no
strontium-90 standard for milk, the standard for
drinking water is 8 pCi/L.
Iodine-129 was identified by high-resolution mass
spectrometry in seven milk samples tested (Table
5.4.2). In recent years, the levels of iodine-129 in
milk collected from generally downwind dairies at
Sagemoor and East Wahluke have persisted at levels
two to four times greater than levels measured
upwind in Sunnyside (Figure 5.4.3). Iodine-129
concentrations have been declining with the end of
nuclear production activities onsite. Iodine-129
contributes less than 1% of the dose to the
maximally exposed individual (MEI) through the
consumption of dairy products (see Section 6.0).
The maximum observed concentration of
iodine-129 in milk in 1994 was
. While there is no
iodine-129 standard for milk, the standard for
drinking water is 1 pCi/L.
Three of the 21 (14%) milk samples collected and
analyzed for cesium-137 in 1994 contained
detectable concentrations (>4.0 pCi/L). There was
no apparent difference between results upwind and
downwind of the Site. The maximum observed
concentration of cesium-137 in milk in 1994 was
. While there is no cesium-137
standard for milk, the standard for drinking water is
200 pCi/L. No other gamma emitters were
consistently detectable (Bisping 1995).
in a shell sample from Sagemoor. Strontium-90
was not detected in the edible portion of the eggs
collected in 1994, nor has it been detected in earlier
samplings of the edible portion (Dirkes et al. 1994).
Strontium-90 has been previously monitored in
Canada goose egg shells as an indicator of
environmental contamination (Poston 1994);
however, this is the first year that chicken egg shells
have been analyzed. No measurable concentrations
of any manmade gamma emitter, such as
cesium-137, were found in chicken or egg samples.
In 1994, manmade radionuclides were not detected in samples of locally produced beef.
Leafy vegetables are sampled because of the potential deposition of airborne contaminants, and at some locations, deposition from overhead irrigation. Leafy vegetables were provided by the Bailie Memorial Youth Ranch in the East Wahluke sampling area and Country Haven Academy in the Sagemoor Area. All vegetable samples were analyzed for gamma-emitting radionuclides and strontium-90; in addition, tomatoes from selected locations were analyzed for tritium, and potatoes from selected locations were analyzed for plutonium-238, plutonium-239,240, technetium-99, and uranium isotopes. Tritium is monitored because it has been released into the atmosphere from Site facilities and to the Columbia River via shoreline ground-water springs. Strontium-90 is monitored because it is released into the Columbia River at the N Springs and is known to accumulate in some plants. Technetium-99 is monitored because it is known to enter the Columbia River through shoreline seeps and springs, has a long half-life, and can accumulate in farm products that may be irrigated with Columbia River water withdrawn downstream from Hanford. Iodine-129 is monitored because it can move through the air-vegetation-human food chain. Cesium-137 is monitored because it is present in Hanford wastes and atmospheric fallout from weapons testing. Isotopes of uranium are monitored because they enter the Columbia River in springs near the 300 Area and are known to accumulate in soil and vegetation. Plutonium-238 and plutonium-239,240 are monitored because of past releases and to assure the public that concentrations of plutonium isotopes are not a concern in vegetables.
) and Sagemoor sample
() exceeded the detection
limit of 0.005 pCi/g. For tomato samples in 1994,
no manmade radionuclides were detected above the
detection limit.
Carrots and potatoes were also sampled at several
locations around Hanford. The only radionuclide
measured was strontium-90
(), at the detection limit.
Measurements of gamma emitters, plutonium-238,
plutonium-239,240, technetium-99, and uranium
isotopes were all less than their respective detection
limits.
A special sampling of asparagus was conducted in
1994 at Riverview, Sagemoor, and Sunnyside. The
only radionuclide found in asparagus was
strontium-90 in samples collected from all three
locations. Concentrations were at the detection
limit of 0.005 pCi/g. The only location with
concentrations of uranium above the detection limit
was Riverview (
uranium-238). A more extensive study of uranium
in asparagus conducted in 1990 (Tiller and Poston
1992) concluded that there was no difference
between wild asparagus collected onsite and
harvested asparagus collected offsite. The
Riverview site was not sampled in that study;
however, the Sagemoor site had the highest
concentrations of uranium-238 in 1990.
Figure 5.4.1
Table 5.4.2
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