Fourth Quarter 2007
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 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 and large game animals sampled during the fourth quarter of 2007.
Milk samples were collected weekly in Ucon until the dairy ceased operations in late November, after which the weekly sample was collected in Idaho Falls. Monthly samples were collected at seven other locations around the INL Site (Figure 11) during the fourth quarter of 2007. 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 manmade 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 all four samples analyzed at levels within historical measurements, ranging from 0.36 to 0.57 pCi/L (Table C-7 in Appendix C). Tritium analysis was inadvertently not performed as scheduled in November.
Eight potato samples were collected from area growers and from one out-of-state location (Colorado). All samples were analyzed for gamma emitting radionuclides and 90Sr. Cesium-137 was initially measured in one sample-the sample from Mud Lake-but this value was not confirmed upon recount. Strontium-90 was not detected in any of the samples. 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).
No large game animals were available for sampling during the fourth quarter of 2007.
Twelve ducks were collected during 2007. Four were collected from wastewater ponds located at the Reactor Technology Complex (RTC) facility, six came from wastewater ponds near the Materials and Fuels Complex (MFC) facility, and two control samples were collected near the Fort Hall Bottoms. Each duck sample was divided into three sub-samples: one consisting of edible tissue (muscle, gizzard, heart and liver); viscera; and a remainder sample that includes all remaining tissue (bones, feathers, feet, bill, head, and residual muscle). All were analyzed for gamma emitting radionuclides, 90Sr, 238Pu, 239/240Pu, and 241Am. Concentrations of radionuclides measured in the edible tissues of 2007 waterfowl are shown in Table C-9 (Appendix C).
Several manmade radionuclides were detected in the samples taken from the RTC ponds. These included 241Am, 137Cs, 51Cr, 60Co, 90Sr, and 65Zn. Of these six, three (241Am, 137Cs, and 60Co) were found in the edible tissues. Three radionuclides, 241Am, 137Cs, and 90Sr, were also detected in the birds from the MFC ponds. One manmade radionuclide (90Sr) was found in the control samples.
Since manmade radionuclides were found more frequently and at higher concentrations in ducks taken from the INL Site, it is assumed that the INL Site is the source of these detections. Concentrations of the detected radionuclides from RTC were similar to those from 2006, or significantly lower in the case of 137Cs than those found in 2005. Measured concentrations were also lower than those in ducks taken during a 1994-1998 study (Warren et al. 2001). The ducks were not taken directly from the two-celled hypalon-lined radioactive wastewater RTC Evaporation Pond but from an adjacent sewage lagoon. However, it is likely that the birds also used the RTC Evaporation Pond.
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 2007 was estimated to be 0.015 mrem (0.00015 mSv). This dose is lower than dose estimates for some previous periods. The maximum dose estimated for the period from 1993 through 1998 was 0.89 mrem (0.009 mSv) and from 2000 through 2004 was 0.08 mrem (0.0008 mSv). 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 (0.54 mSv).
Fourth Quarter 2007
INL Quarterly Site Environmental Report
Return to Index