| Class | Description |
|---|
| 1 | Contained use of no or negligible risk, for which containment level 1 is appropriate to protect human health and the environment. |
| 2 | Contained use of low risk, for which containment level 2 is appropriate to protect human health and the environment. |
| 3 | Contained use of moderate risk, for which containment level 3 is appropriate to protect human health and the environment. |
| 4 | Contained use of high risk, for which containment level 4 is appropriate to protect human health and the environment. |