Biological Effects of Low-Level Exposures, more commonly referred to as BELLE, began as a conference in May 1990. Its members are committed to the enhanced understanding of low-dose responses of all types to human exposures to chemical and physical agents, whether of an expected or paradoxical nature. The focus of BELLE encompasses dose-response relationships to toxic agents, pharmaceuticals, and natural products over wide dosage ranges in both in vitro systems and in vivo systems, including human populations. While BELLE promotes the scientific understanding of low-level effects, its primary goal is the scientific evaluation of existing literature and ways to improve research and assessment methods.