Terminology
Median Lethal Concentration (LC50) – The chemical concentration that is expected to kill 50% of a group of organisms.
Median Effective Concentration (EC50) – The chemical concentration that is expected to have one or more specified effects in 50% of a group of organisms.
Critical Body Residue (CBR) – An approach that routinely examines whole-body chemical concentrations of an exposed organism that is associated with an adverse biological response.
Baseline toxicity – Refers to narcosis which is a depression in biological activity due to toxicants being present in the organism.
Biomagnification – The process by which the concentration of a chemical in the tissues of an organism increases as it passes through several levels in the food web.
Lowest Observed Effect Concentration (LOEC) – The lowest test concentration that has a statistically significant effect over a specified exposure time.
No Observed Effect Concentration (NOEC) – The highest test concentration for which no effect is observed relative to a control over a specified exposure time.
Maximum Acceptable Toxicant Concentrations (MATC) – An estimated value that represents the highest “no-effect” concentration of a specific substance within the range including the NOEC and LOEC.
Application Factor (AF) – An empirically derived “safe” concentration of a chemical.
Biomonitoring – The consistent use of living organisms to analyze environmental changes over time.
Effluent – Liquid, industrial discharge that usually contain varying chemical toxicants.
Quantitative Structure-Activity Relationship (QSAR) – A method of modeling the relationship between biological activity and the structure of organic chemicals.
Mode of Action – A set of common behavioral or physiological signs that represent a type of adverse response.
Mechanism of Action – The detailed events that take place at the molecular level during an adverse biological response.
KOW – The octanol-water partition coefficient which represents the ratio of the concentration of octanol to the concentration of chemical in the water.
Bioconcentration Factor (BCF) – The ratio of the average chemical concentration in the tissues of the organism under steady-state conditions to the average chemical concentration measured in the water to which the organisms are exposed.
All terms were derived from Rand.
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