An oncology clinic stores two liquid radioactive waste samples, Sample A and Sample B, in a secure disposal facility. Both samples are initially prepared with an activity of 600 MBq. Their radioactive decay is monitored over a period of 24 days. The results are shown in the graph and the table below.
| Time (days) | Activity of Sample A (MBq) | Activity of Sample B (MBq) |
|---|---|---|
| 0 | 600 | 600 |
| 4 | 547 | 300 |
| 8 | 499 | 150 |
| 12 | 455 | 75 |
| 16 | 415 | 38 |
| 20 | 378 | 19 |
| 24 | 345 | 9 |
Suggest one reason why Sample A could pose a greater long-term environmental hazard in the storage facility than Sample B.