ABSTRACT
Beginning in the early 1700s with the commercial production of acids and alkalis, the modern chemical industry has grown steadily, with the number and complexity of chemicals entering the market rising sharply in the late 1800s and in the post-World War II era. Risk-management protocols sometimes single out persistent, bioaccumulative, and toxic (PBT) compounds. Most regulatory programs lack one important criterion, the half-life in air, that would identify PBT compounds that might migrate beyond national borders. Under the Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals, the European Union does not factor the half-life in air into PBT assessments. In part due to the variations in the criteria for defining PBT compounds, the number of substances recognized as PBT varies widely between the jurisdictions but typically numbers less than 100.
