| Relationships | Role | Relationship Start | Relationship End |
| B.U.S. Berzelius Umwelt-Services A.G. | Parent | 12/31/1991 | 12/30/1993 |
| Mg Technologies Ag | Parent | 12/31/1989 | 12/30/1991 |
| Mg Technologies Ag | Parent | 12/31/1987 | 12/30/1989 |
| Horsehead Resource Development Co., Inc. | Subsidary | 12/31/1991 | 12/30/1993 |
| B.U.S. Nartec, Inc. | Subsidary | 12/31/1991 | 12/30/1993 |