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, alfalfa, grain, potatoes, lettuce, large game animals, 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. Alfalfa is collected during the second quarter, lettuce and grain 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 agricultural products samples available during the fourth quarter of 2017.
Milk samples were collected weekly at Idaho Falls and Terreton. Monthly samples were collected at five other locations around the INL Site (Figure 12) during the fourth quarter of 2017. In addition to the local locations, commercially-available organic milk (from Colorado) was purchased as a control sample each month. All samples were analyzed for gamma emitting radionuclides, with particular emphasis on Iodine-131. Samples in November were also analyzed for 90Sr and tritium.
Figure 12. ESER agriculture product sampling locations. Milk is collected at locations identified by blue circles.
Neither 131I nor 137Cs was detected in any weekly or monthly samples during the fourth quarter. No other human-made gamma-emitting radionuclides were found either. Data for 131I and 137Cs in milk samples are listed in Appendix C, Table C-8.
Results for 90Sr and tritium are listed in Appendix C, Table C-9. Strontium-90 was detected in two of the six samples analyzed, including the control sample. A seventh sample from Blackfoot was not analyzed because of insufficient sample. The maximum concentration of 0.38 pCi/L from the Control location and the average concentration of 0.16 pCi/L are in the lower portion of the range for these values over the past several years. The presence of 90Sr at similar levels in samples from near the INL Site and distant from the INL Site (as well as the organic milk from Colorado), indicates that there is no INL Site impact of the results. There is no DCS for 90Sr in milk; however, for comparison the results were well below the drinking water DCS of 1.1 x 103 pCi/L.
Tritium was also detected in one of seven samples analyzed at 86.8 pCi/L in the sample from Terreton. The result similar to those previously measured and similar to those found in other liquid media like precipitation. There is no DCS for tritium in milk, but the results were well below the DCS for tritium in drinking water (1.9 x 106 pCi/L).
Locally-grown potatoes from seven southeast Idaho locations (Figure 12) and one duplicate were analyzed for gamma-emitting radionuclides like 137Cs and for 90Sr. A control sample from a local grocery store (grown in Washington state) was also analyzed. No human-made gamma-emitters were found in any sample. Strontium-90 was reported in the sample from Terreton (2.69 pCi/kg) and in the duplicate sample from Arco at 3.3 pCi/kg, but not in the primary sample from the same location. Both 137Cs and 90Sr are present in the soil as a result of worldwide fallout from nuclear weapons testing, but they are only occasionally detected in potato samples. This is because potatoes are generally less efficient at removing radioactive elements from soil than leafy vegetables such as lettuce. Data for potato samples are listed in Appendix C, Table C-10.
Muscle tissue was collected from one game animal, an elk, during the fourth quarter. No manmade gamma-emitting radionuclides were detected (Appendix C, Table C-11).
Waterfowl are collected each year by the ESER contractor at ponds on the INL Site and at a location off the INL Site. Three waterfowl collected from wastewater ponds located at the Advanced Test Reactor (ATR) Complex plus four control waterfowl collected from American Falls Reservoir were analyzed for gamma-emitting radionuclides, 90Sr, and actinides (americium-241 [241Am], plutonium-238 [238Pu], and plutonium-239/240 [239/240Pu]). These radionuclides were selected because they have historically been measured in liquid effluents from some INL Site facilities. Each sample was divided into the following three sub-samples: 1) edible tissue (muscle, gizzard, heart, and liver), 2) external portion (feathers, feet, and head), and 3) all remaining tissue.
A total of six human-made radionuclides were detected in the samples from at least one of the ducks collected at the ATR Complex ponds. These were cobalt-60 (60Co), zinc-65 (65Zn), 90Sr, 137Cs, 238Pu, and 239/240Pu. The Green-winged Teal, collected from the sewage lagoons at ATR Complex had four of these radionuclides in edible tissue (Appendix C, Table C-12). In the control ducks, 90Sr and 239/240Pu were detected in the external and remainder portions of some ducks, but it was not found in the edible tissues.
The maximum potential dose from eating 225 g (8 oz) of duck meat collected in 2017 was calculated. Doses from consuming waterfowl are conservatively based on the assumption that ducks are eaten immediately after leaving the pond and no radioactive decay occurs. The maximum potential dose of 0.046 mrem from these waterfowl samples is much lower than the dose estimated for 2016 (0.49 mrem), the last time waterfowl were collected. This because the hypalon liner was removed from the west disposal pond in 2016 and any associated debris was removed with the liner and was no longer available to waterfowl.
Radiation has always been a part of the natural environment in the form of cosmic radiation, cosmogenic radionuclides [carbon-14 (14C), Beryllium-7 (7Be), and tritium (3H)], and naturally occurring radionuclides, such as potassium-40 (40K), and the thorium, uranium, and actinium series radionuclides which have very long half lives. Additionally, human-made radionuclides were distributed throughout the world beginning in the early 1940s. Atmospheric testing of nuclear weapons from 1945 through 1980 and nuclear power plant accidents, such as the Chernobyl accident in the former Soviet Union during 1986, have resulted in fallout of detectable radionuclides around the world. This natural and manmade global fallout radioactivity is referred to as background radiation. MORE
The primary concern regarding radioactivity is the amount of energy deposited by particles or gamma radiation to the surrounding environment. It is possible that the energy from radiation may damage living tissue. When radiation interacts with the atoms of a given substance, it can alter the number of electrons associated with those atoms (usually removing orbital electrons). This is called ionization. MORE