Endpoint Code

Endpoint Name: Definition

ATCN

Asymptotic Threshold Concentration: The concentration of a chemical at which some percentage of a population of test organisms is in a state of approximate homeostasis for some prolonged period of time.

BAF

Bioaccumulation Factor: A value that is the "ratio of the concentration of a chemical in the organism to that in the medium. Bioaccumulation refers to both uptake of dissolved chemicals from water (bioconcentration) and uptake from ingested food and sediment residues. BAF values are only reported in the terrestrial database. Values reported as BCF in pore water or hydroponic studies are reported in ECOTOX as a BAF.

BCF

BCF = [K1 (uptake)] / [K2 (elimination)]

BCFD

BCF dry-weight: Bioconcentration factor derived using dry weight.

ECxx

xx% Effective Concentration: Effective concentration for xx% of tested organisms.

ED50

Median Effective Dose: Effective dose for 50% of the organisms tested. Used when an effect other than death is the observed endpoint.

EC50

Median Effective Concentration: Effective concentration for 50% of the organisms tested. Used when an effect other than death is the observed endpoint.

ET50

Median Effective Time: Median time to effect or estimated mean survival time.

ICxx

xx% Inhibition Concentration: Statistically or graphically estimated concentration of test material, under specified concentrations, is expected to cause a xx% inhibition of a biological process for which the data are dichotomous.

IC50

Median Inhibition Concentration: Statistically or graphically estimated concentration of test material, under specified concentrations, is expected to cause a 50% inhibition of a biological process for which the data are dichotomous.

LC50

Median Lethal Concentration: Statistically estimated concentration that is expected to be lethal to 50% of a group of organisms tested. Death may be defined by the mortality, intoxification and population effect groups. TLms and TL50s with death as the measured endpoint are reported as LC50*.

LCxx

xx% Lethal Concentration: Lethal concentration for xx% of the tested organisms.

LD50

Median Lethal Dose: A statistically estimated dose that is expected to be lethal to 50% of a group of organisms.

LDxx

xx% Lethal Dose: A statistically estimated dose that is expected to be lethal to xx% of a group of organisms.

LOEC
LOEL

Lowest Observed Effect Concentration/Level: Lowest concentration (LOEC) or level (LOEL) that has a statistically significant adverse effect on the tested organisms. The term MEC (Minimum Effective Concentration) is coded as LOEC.

LT50

Mean Survival Time: Represents time until death of 50% of the tested organisms.

LETC

Lethal Threshold Concentration: Toxicity curve asymptotic concentration indicating an incipient LC50 value. Acute lethal action has essentially ceased.

LTxx

xx% Death Time: Time until xx% test organisms are dead.

MATC

Maximum Acceptable Toxicant Concentration: Hypothetical threshold concentration that is the geometric mean between the NOEC and LOEC concentration. The term Chronic Value (ChV) is encoded as MATC.

NOEL

No Observed Effect Concentration/Level: Concentration or dose producing effects not significantly different from responses of controls according to author's reported statistical test (NOEAL/NOEC)

NR-LETH

Lethal: 100% mortality or 0% survival including algicidal and herbicidal effects. No statistically derived endpoint reported. This is only used in the aquatic database.

NR-ZERO

Zero Mortality: 0% mortality or 100% survival of organisms. (No statistically derived endpoint reported). This is only used in the aquatic database.

ST50

Medium Survival Time: Time required for 50% of a population to die from a given dose.

STxx

xx% Survival Time: Time required for xx% of a population to die from a given dose.

T1/2

Time One-Half: Time required for one-half of ingested dose to be eliminated.

TD50

Median Ataxia Dose: Dose required to produce ataxia in 50% of the animals.

TDxx

xx% Ataxia Dose: Dose required to produce ataxia in xx% of the animals