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, 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, and large game sampled during the first quarter of 2002. A summary of approximate minimum detectable concentrations (MDCs) for radiological analyses is provided in Appendix B. There no regulatory standards for radionuclide concentrations in agricultural products and wildlife tissues.
Milk samples were collected weekly in Idaho Falls and monthly at eight other locations around the INEEL (Figure 11 below) during the first quarter of 2002. All samples were analyzed for gamma emitting radionuclides. Samples are analyzed for 90Sr during the second and fourth quarters.
Data for 131I and 137Cs in milk samples are listed in Table C-7. No Iodine-131 (131I) was detected in any milk sample during this quarter. One sample collected from Idaho Falls in mid-January had a 137Cs concentration (1.6 pCi/L) greater than its 2s uncertainty.
The detection of 137Cs in milk around the INEEL at very low concentrations is not unusual and is indistinguishable from 137Cs levels expected from historical fallout events (e.g. from nuclear weapons tests and Chernobyl) (EPA 1997). There are no established limits for 137Cs in milk but, for comparison, the EPA has set the limit for 137Cs under the Safe Drinking Water Act at 120 pCi/L (4.4 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 (1.6 ± 1.5 pCi/L [5.9 ± 5.5 x 10-2 Bq/L) measured in milk during the first quarter, 2002 is many times lower than the 120 pCi/L limit.
Large Game Animal Sampling
Fourteen game animals were sampled during the first quarter of 2002. All were killed as a result of vehicular collisions. These accidents involved six mule deer (Odocoileus hemionus) and eight pronghorn antelope (Antilocapra americana). 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-8.
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 detected in the muscle of two pronghorns above the respective 2s values on March 5 and 6, 2002.
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 fallout from past weapons
testing and nuclear accidents (i.e., Chernobyl).