Persistent substances may remain in the natural and man-made environments for an indefinite time. These compounds may accumulate to reach levels that are harmful to health, environment and natural resources. Such contamination may be poorly reversible or even irreversible, and could render natural resources such as soil and water unusable far into the future. As such, there is a need to design chemicals and materials, particularly those that are intentionally or unintentionally distributed in the environment, that are stable during their useful life, and then degrade once they are no longer functionally necessary. Designing for degradation is necessary but not sufficient to realize the goals of sustainable chemistry; the subsequent degradation products should, themselves, be benign to human health and the environment.