Agricultural Products and Wildlife Sampling

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 INEEL and Southeast Idaho. Specifically, milk, wheat, potatoes, garden lettuce, sheep, big game, waterfowl, doves, and marmots are sampled. Milk is sampled throughout the year. Sheep are sampled during the second quarter. Lettuce and wheat are sampled during the third quarter, while potatoes and waterfowl are collected during the 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 sampled during the third quarter of 2002. A summary of approximate minimum detectable concentrations (MDCs) for radiological analyses is provided in Appendix B. There are no regulatory standards for radionuclide concentrations in agricultural products or wildlife tissues.

• Milk Sampling
• Potato Sampling
• Large Game Animal Sampling
• Waterfowl Sampling

Milk Sampling

Milk samples were collected weekly in Idaho Falls and monthly at nine other locations around the INEEL (Figure 12) during the fourth quarter of 2002. All samples were analyzed for gamma emitting radionuclides. Samples are analyzed for ⁹⁰Sr during the second and fourth quarters.
 

Figure 12.  ESER Program milk sampling locations.

Data for ¹³¹I and ¹³⁷Cs in milk samples are listed in Table C-8. Iodine-131 or ¹³⁷Cs were not measured above the 2s value in any milk sample during this quarter. Iodine-131 was detected in one sample, the October sample from Roberts, exceeding the 2s value. No samples had ¹³⁷Cs concentrations greater than their 2s uncertainty.

Strontium-90 was measured in four samples above the 2s value. The detection of ⁹⁰Sr in milk around the INEEL at very low concentrations is not unusual and is indistinguishable from ⁹⁰Sr levels expected from historical fallout events (e.g. from nuclear weapons tests and Chernobyl) (EPA 1997). There are no established limits for ⁹⁰Sr in milk but, for comparison, the EPA has set the limit for ⁹⁰Sr under the Safe Drinking Water Act at 8 pCi/L (0.3 Bq/L). This limit is based on a 4 mrem per year exposure limit and the assumption that two liters per day are consumed. The maximum concentration (0.84 ± 0.72 pCi/L [0.03 ± 0.02 Bq/L) measured in milk during the fourth quarter, 2002 is many times lower than the 8-pCi/L limit.  All resulst are reported in Table C-9, Appendix C.
 

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Potato Sampling

Nine potato samples were collected from area growers and from out-of-state locations. All samples were analyzed for gamma emitting radionuclides and ⁹⁰Sr.  No ⁹⁰Sr was detected in any of the samples.  Cesium-137 was measured in one sample from Mud Lake above its respective 2s value.  The concentration of ¹³⁷Cs from Mud Lake was 3.4 ± 3.3 pCi/kg (dry) (0.13 ± 0.12 Bq/kg [dry]).

Data for ¹³⁷Cs and ⁹⁰Sr in all potato samples taken during the fourth quarter are listed in Table C-10 and Table C-11 (Appendix C), respectively.

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Large Game Animal Sampling

Three game animals were sampled during the fourth quarter of 2002. All were killed as a result of vehicular collisions. These accidents involved two mule deer (Odocoileus hemionus) and one elk (Cervus elaphus). Efforts were made to collect samples of thyroid, liver, and muscle tissue from each animal, but due to their condition at the time of sampling not all animals provided all samples. Cesium-137 and ¹³¹I data for all big game samples are listed in Appendix C,
Table C-12.

Each sample collected was analyzed for gamma emitting radionuclides. Liver and muscle tissue of all animals had detectable concentrations of naturally occurring potassium-40. Cesium-137 was measured in the liver tissue of the elk sampled on October 14, 2002 above the respective 2s value. No ¹³¹I was measured in any game sample for the quarter.

The concentrations measured in the above samples are within the range of values for samples collected in the past. Likewise, the presence of ¹³⁷Cs is commonly associated with plant uptake of fallout from past weapons testing and nuclear accidents (i.e., Chernobyl).
 

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Waterfowl Sampling

Eleven waterfowl were collected during 2002: two each from the control locations of Mud Lake and Heise, three from the northeast Test Reactor Area (TRA) pond, and four from the TAN pond. All were analyzed for gamma emitting radionuclides with a subset analyzed for ⁹⁰Sr, ²³⁸Pu, ^239/240Pu, and ²⁴¹Am. Concentrations of radionuclides measured in edible tissues are shown in Table 4. Seven waterfowl had measurable levels of at least one radionuclide in edible tissue. Of the radionuclides measured at each location, Mud Lake, the TRA NE pond, and TAN, each had three. Curium-141 (¹⁴¹Cm), niobium-95 (⁹⁵Nb), and ⁹⁰Sr were detected at concentrations greater than their 2s values in the muscle tissue of three of the waterfowl sampled. No ¹³⁷Cs was measured above the 2s concentration in any edible tissue. Duck hunting is not allowed on the INEEL, but a maximum potential exposure scenario to humans would be someone collecting a contaminated duck and immediately consuming all muscle, liver, heart, and gizzard tissue (average 225 g). The maximum potential dose from eating 225 g (8 oz) of meat from the most contaminated ducks collected in 2002 was estimated to be 0.004 mrem. This dose is an order of magnitude lower than last years estimated dose of 0.89 mrem. This is attributed primarily to the fact that waterfowl from the TRA Warm Waste Pond, containing low levels of radionuclides, were not taken in 2002. This dose is far less than 240 mrem we receive each year from ambient sources and the 100 mrem per year DOE regulatory dose limit. Results for all duck samples are listed in Table C-13 of Appendix C.

Table 4. Measured radionuclides in edible tissues of waterfowl.

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