No Observable Effect Level (NOEL) : In toxicology, the concentration of a substance at (and below) which exposure produces no evidence of injury or impairment
Barbara A. Plog, Patricia J. Quinlan, Jodey B. Schonfeld and Patricia M. Dewey (editors), Fundamentals of industrial hygiene 5th ed., Appendix E - Glossary (Michael Horowitz, MS, CIH - Compiler), National Safety Council, Illinoise, USA 2002. http://www.wbcsd.org/web/projects/cement/tf3/fihAp pendices.pdf, (Env and Occupn Sfty and Hlth - Amer) {680}