Introduction

Chemical standards are widely used to protect the environment and human health from substances released by human activity. Generally, standards relate to doses or concentrations in the environment for specific chemicals, below which unacceptable effects are not expected to occur. Many standards are legally enforceable numerical limits, such as Environmental Quality Standards for List 1 chemicals in water or Annex X and VIII standards under the European Water Framework Directive. Others are not mandatory but are contained in guidelines, codes of practice, or sets of criteria for deciding individual cases. Some standards are not set by governments but carry authority for other reasons, especially the scientific eminence or market power of those who set them (e.g., World Health Organization guidelines).