Baseline and Operational Monitoring Results
Baseline and operational monitoring results are presented in the following table. To maintain confidentiality, no individual results are presented. To interpret the monitoring results, one should compare the percentage of results greater than adecision level (LC) for the operational monitoring counts to the same percentage for the baseline counts. If the operational monitoring percentage is statistically greater than the baseline percentage, this suggests that a particular radionuclide may now be present (or present at a greater frequency) in the local population. The percentage of results greater than LC for operational monitoring would be considered statistically different from the baseline percentage if:
- the baseline percentage is not contained within the margin of error for the operational monitoring percentage
(Click here for a more detailed explanation of the analytical and statistical methods)
Count Results as of June 1, 2003
|
Radionuclide |
In Vivo Count Type |
Baseline Counts
(prior to 3/27/99)
n = 367 |
Operational Monitoring
Counts
(3/27/99 through 6/1/03)
n = 508 |
| % of Results >aLC |
% of Results >aLC |
bMargin of Error (%) |
| 241Am |
Lung |
5 |
4 |
3 to 6 |
| 144Ce |
Lung |
5 |
4 |
2 to 5 |
| 252Cf |
Lung |
4 |
6 |
4 to 9 |
| 244Cm |
Lung |
6 |
4 |
3 to 6 |
| 155Eu |
Lung |
7 |
4 |
3 to 6 |
| 237Np |
Lung |
4 |
4 |
2 to 5 |
| 210Pb |
Lung |
4 |
5 |
3 to 7 |
| Plutonium
Isotope |
Lung |
6 |
6 |
4 to 8 |
| 232Th
via 212Pb |
Lung |
c34 |
c36 |
32 to 40 |
| 232Th |
Lung |
5 |
6 |
4 to 7 |
| 232Th
via 228Th |
Lung |
4 |
5 |
3 to 7 |
| 233U |
Lung |
6 |
9 |
7 to 12 |
| 235U
/ 226Ra |
Lung |
11 |
10 |
7 to 13 |
| Natural
Uranium via 234Th |
Lung |
5 |
6 |
4 to 8 |
| 133Ba |
Whole Body |
4 |
3 |
2 to 5 |
| 140Ba |
Whole Body |
5 |
4 |
3 to 6 |
| 141Ce |
Whole Body |
4 |
4 |
2 to 6 |
| 58Co |
Whole Body |
4 |
3 |
2 to 5 |
| 60Co |
Whole Body |
c55 |
c31 |
27 to 36 |
| 51Cr |
Whole Body |
6 |
5 |
3 to 7 |
| 134Cs |
Whole Body |
2 |
2 |
1 to 4 |
| 137Cs |
Whole Body |
28 |
22 |
18 to 25 |
| 152Eu |
Whole Body |
7 |
6 |
4 to 8 |
| 154Eu |
Whole Body |
4 |
3 |
2 to 5 |
| 155Eu |
Whole Body |
4 |
4 |
2 to 6 |
| 59Fe |
Whole Body |
4 |
6 |
4 to 8 |
| 131I |
Whole Body |
5 |
3 |
1 to 5 |
| 133I |
Whole Body |
3 |
4 |
2 to 5 |
| 192Ir |
Whole Body |
4 |
4 |
2 to 6 |
| 40K |
Whole Body |
100 |
100 |
dNC |
| 54Mn |
Whole Body |
c12 |
c10 |
8 to 13 |
| 103Ru |
Whole Body |
2 |
1 |
0 to 2 |
| 106Ru |
Whole Body |
4 |
4 |
2 to 5 |
| 125Sb |
Whole Body |
5 |
4 |
2 to 6 |
| 232Th
via 228Ac |
Whole Body |
c35 |
c25 |
22 to 29 |
| 88Y |
Whole Body |
8 |
6 |
4 to 8 |
| 65Zn |
Whole Body |
0 |
0 |
dNC |
| 95Zr |
Whole Body |
7 |
5 |
3 to 6 |
aTo determine whether or not activity has been detected in a particular person, the parameter LC is used. The LC represents the 95th percentile of a null distribution that results from the differences of repeated, pair wise background measurements. An individual result is assumed to be statistically greater than background if it is greater than LC. However, it is important to consider that the use of this criterion (LC) will result in a statistically inherent 5% false positive error rate per pair wise comparison (5% of all measurements will be determined to be positive when there is truly no activity in the person). For the baseline counts, a 95% confidence interval for a random, 5% error rate is 1 to 9%. So, one would expect to see between 1 and 9% of bioassay results to be greater than LC even when there is no radionuclide present in the local population. An observed percentage outside this interval would be considered statistically inconsistent with a random 5% false positive error rate.
bThe margin of error represents the 95% confidence interval of the observed percentage. Under complete replication of this experiment, one would expect the confidence interval to include the true population percentage 95% of the time, if the sample was representative of the true population.
cThese radionuclides are present in the shield background, so these radionuclides are expected to be detected periodically. The most likely source of detection for these radionuclides is not the counting subject, but the counting shield.
dNot Calculated: the margin of error cannot be calculated for the observed percentage because the sample size for operational monitoring counts is as yet too small. When sufficient counts are performed, the margin of error will be calculated.
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