ABSTRACT
The chemicals used as reagents are often highly reactive and are used as they are. As such, they may react readily with components of the human body, such as water, or the hydroxyl and amino groups of proteins and nucleic acids. The next chapters will deal with efforts to replace these toxic materials with inherently safer chemistry. It may not be possible to replace them completely. This leads to a hierarchy of approaches (a tiered approach follows) from least change to the most change:
No change: Those using the process are con dent that they can handle it. They may not have had any accidents recently.
