Fourth Quarter 2008
INL Quarterly Site Environmental Report
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Another potential pathway for contaminants to reach humans is through the food chain. The ESER Program samples multiple agricultural products and game animals from around the INL Site and Southeast Idaho. Specifically, milk, wheat, potatoes, garden lettuce, big game, and waterfowl are sampled. Milk is sampled throughout the year and large game animals are sampled whenever large game animals are killed onsite from vehicle collisions. Lettuce and wheat are sampled during the third quarter, while potatoes are collected during the fourth quarter. Waterfowl are collected in either the third or fourth quarter. See Table A-1, Appendix A, for more details on agricultural product and wildlife sampling. This section discusses results from milk, lettuce, wheat and large game animals sampled during the fourth quarter of 2008.
Milk samples were collected weekly in Idaho Falls. Monthly samples were collected at seven other locations around the INL Site (Figure 11) during the fourth quarter of 2008. All samples were analyzed for gamma emitting radionuclides. During the second quarter, samples from half of the locations are analyzed for 90Sr and half are analyzed for tritium. In the fourth quarter the analyses are reversed, so that each location receives one analysis for 90Sr and tritium each year.
No Iodine-131 or other gamma-emitting radionuclides were detected in any sample. Data for 131I and 137Cs in milk samples are listed in Appendix C, Table C-6.
Strontium-90 was detected in three of four samples analyzed at levels within
historical measurements, ranging from 0.24 to 0.67 pCi/L (Table C-7 in
Appendix C.) Tritium was detected in
one of four samples analyzed, also well within the range of historical
measurements (Table C-7).
Eight potato samples were collected from area growers and from two out-of-state locations (Colorado and Oregon). All samples were analyzed for gamma emitting radionuclides and 90Sr. Cesium-137 was not measured in any samples. Strontium-90 was detected in two of the samples—Idaho Falls and Minidoka. All values were within historic concentrations measured in potatoes collected from farms surrounding the INL and out-of-state areas.
Data for 137Cs and 90Sr in all potato samples taken
during the fourth quarter are listed in Table C -8 (Appendix
C).
Two large game animals (one mule deer and one elk) were sampled on the INL Site during the fourth quarter of 2008. No manmade radionuclides were found in any of the muscle and liver samples No 131I was detected in either of the thyroid samples, but 137Cs was reported just above the detection limit in the mule deer thyroid.
The data for 137Cs and 131I are listed in Appendix C, Table C-11.
Nine ducks were collected during 2008. Four were collected from wastewater ponds located at the Advanced Test Reactor Complex (ATR-C), three came from wastewater ponds near the Materials and Fuels Complex (MFC), and two control samples were collected from Mud Lake. Each sample was divided into the following three sub-samples: 1) edible tissue (muscle, gizzard, heart and liver), 2) viscera, and 3) all remaining tissue (bones, feathers, feet, bill, head, and residual muscle). All were analyzed for gamma-emitting radionuclides, 90Sr, plutonium-238 (238Pu), plutonium-239,240 (239/240Pu), and americium-241 (241Am). Concentrations of radionuclides measured in the edible tissues of 2008 waterfowl are shown in Table C-12 (Appendix C).
Several manmade radionuclides were detected in the samples taken from the ATR-C ponds, including 241Am, 137Cs, cobalt-60 (60Co), 90Sr, and zinc-65 (65Zn). All were also found in at least one edible tissue sample. Birds from the MFC ponds contained 137Cs and 90Sr but neither was found in edible tissues. One detection each for 241Am, 238Pu and 239/240Pu were reported in the control samples.
Since manmade radionuclides were found more frequently and at higher concentrations in ducks taken from the INL Site than in those from other locations, it is assumed that the INL Site is the source of these radionuclides. Concentrations of the detected radionuclides from ATR-C were similar to those from 2006 and 2007, or significantly lower in the case of 137Cs than those found in 2005. The ducks were not taken directly from the two-celled hypalon-lined radioactive wastewater evaporation pond but rather from an adjacent sewage lagoon. However, it is likely that the birds also used the evaporation pond. Measured concentrations were also lower than those in ducks taken during a 1994-1998 study (Warren et al. 2001).
Waterfowl hunting is not allowed on the INL Site, but a maximum potential
exposure scenario to humans would be someone collecting a contaminated duck
directly from the ponds and immediately consuming all muscle, liver, heart, and
gizzard tissue. The maximum potential dose from eating 225 g (8 oz) of meat from
the most contaminated waterfowl collected in 2008 was estimated to be 0.05 mrem.
This dose is lower than dose estimates for some previous periods. The dose
estimated for 2007 was 0.015 mrem. The maximum dose estimated for the period
from 1993 through 1998 was 0.89 mrem and from 2000 through 2004 was 0.08 mrem.
In the late 1970s, when the percolation ponds were still in use, the maximum
dose estimated from eating a contaminated duck was estimated to be 54 mrem.
Fourth Quarter 2008
INL Quarterly Site Environmental Report
Return to Index