The dose of a substance needed to produce a defined toxic effect in 50 percent of the exposed population. It is an infrequently used term, equivalent to ED50 where "toxicity" is the measured "effect"
US Army Center for Health Promotion and Preventive Medicine CHPPM, TG 204 Glossary of Terms For Nuclear, Biological, and Chemical Agents And Defense Equipment (Section 2 - General Terms), MD, USA 2001. http://www.au.af.mil/au/awc/awcgate/army/tg204.pdf , (CBRNE Agt and Def Equip/ Gen Terms - Amer) {487}
Madison County North Carolina Government, Madison County Emergency Operations Plan Glossary (Section 2: General Terms), NC, USA 2009. http://www.madisoncountync.org/eop/Madison_EOP_PDF /Glossary.pdf, (CBRNEmr - Amer) {874}