threshold dose


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Related to threshold dose: Synergistic effect

dose

 [dōs]
the quantity to be administered at one time, as a specified amount of medication or a given quantity of radiation.
absorbed dose that amount of energy from ionizing radiations absorbed per unit mass of matter, expressed in rads.
air dose the intensity of an x-ray or gamma-ray beam in air, expressed in roentgens.
booster dose an amount of immunogen (vaccine, toxoid, or other antigen preparation), usually smaller than the original amount, injected at an appropriate interval after primary immunization to sustain the immune response to that immunogen.
curative dose (CD) a dose that is sufficient to restore normal health. See also median curative dose.
divided dose fractionated dose.
effective dose (ED) that quantity of a drug that will produce the effects for which it is administered. See also median effective dose.
erythema dose that amount of radiation that, when applied to the skin, causes erythema (temporary reddening).
fatal dose lethal dose.
fractionated dose a fraction of the total dose prescribed, as of chemotherapy or radiation therapy, to be given at intervals, usually during a 24-hour period.
infective dose (ID) that amount of a pathogenic agent that will cause infection in susceptible subjects. See also median infective dose and tissue culture infective dose.
lethal dose (LD) that quantity of an agent that will or may be sufficient to cause death. See also median lethal dose and minimum lethal dose.
loading dose a dose of medication, often larger than subsequent doses, administered for the purpose of establishing a therapeutic level of the medication.
maintenance dose the amount of a medication administered to maintain a desired level of the medication in the blood.
maximum tolerated dose tolerance dose.
maximum permissible dose the largest amount of ionizing radiation that one may safely receive within a specified period according to recommended limits in current radiation protection guides. The specific amounts vary with age and circumstance.
median curative dose (CD50) a dose that abolishes symptoms in 50 per cent of test subjects.
median effective dose (ED50) a dose that produces the desired effect in 50 per cent of a population.
median infective dose (ID50) that amount of pathogenic microorganisms that will produce demonstrable infection in 50 per cent of the test subjects.
median lethal dose (LD50) the quantity of an agent that will kill 50 per cent of the test subjects; in radiology, the amount of radiation that will kill, within a specified period, 50 per cent of individuals in a large group or population.
median tissue culture infective dose (TCID50) that amount of a pathogenic agent that will produce infection in 50 per cent of cell cultures inoculated.
minimum lethal dose
1. the amount of toxin that will just kill an experimental animal.
2. the smallest quantity of diphtheria toxin that will kill a guinea pig of 250-gm weight in 4 to 5 days when injected subcutaneously.
reference dose an estimate of the daily exposure to a substance for humans that is assumed to be without appreciable risk; it is calculated using the no observed adverse effect level and is more conservative than the older margin of safety.
skin dose (SD)
1. the air dose of radiation at the skin surface, comprising the primary radiation plus backscatter.
2. the absorbed dose in the skin.
threshold dose the minimum dose of ionizing radiation, a chemical, or a drug that will produce a detectable degree of any given effect.
threshold erythema dose (TED) the single skin dose that will produce, in 80 per cent of those tested, a faint but definite erythema within 30 days, and in the other 20 per cent, no visible reaction.
tissue culture infective dose (TCID) that amount of a pathogenic agent that will produce infection when inoculated on tissue cultures; used with a numeric qualifier.
tolerance dose the largest quantity of an agent that may be administered without harm. Called also maximum tolerated dose.

thresh·old dose

(threshōld dōs)
Minimal dose amount of medicine needed to obtain a desired therapeutic reaction.

thresh·old dose

(threshōld dōs)
Minimum dose that will result in the desired effect.
References in periodicals archive ?
The recommendation in Science & Decisions for harmonizing cancer and non-cancer risk assessment involves a paradigm for quantitative risk assessment composed of three conceptual models that envision three categories of dose responses derived from mechanistic considerations: conceptual model 1, threshold dose response at the individual level and linear response at the population level; conceptual model 2, threshold response at the individual level and nonlinear response at the population level; and conceptual model 3, linear response at both the individual and the population level.
Deterministic (nonstochastic) effects are those for which the severity of the effect (rather than the probability) increases with increasing dose and for which there is a threshold dose. Below the threshold dose, these effects are not observed.
Tables 4 and 5 list the model estimates for the threshold dose and [ED.sub.30] dose.
In our 2003 study (Calabrese and Baldwin 2003b) we concluded that hormesis was more common than the threshold dose response based on the observation that approximately 1,800 responses below the estimated threshold were nonrandomly distributed about the control in a manner to strongly support an hormetic interpretation.
The evaluation would also suggest the presence of small threshold doses that increase with increasing mass.
We chose a range of doses based upon data from GD-15 exposures in which the reported threshold dose for obvious reduction of cortical volume by MAM is > 10 mg/kg (Fischer et al.
Hennes (2012) remarked "The reference to toxicological endpoints from which TTC values were derived is however not of particular significance in the application of the TTC approach, unless it could be identified whether a compound was likely to produce the effect of concern." However, this is not playing to the full potential of TTC, which could nowadays with larger databases be derived endpoint-specifically and allow for many endpoints to set higher threshold doses, i.e., broader applicability to more chemicals.
A further 9 out of 26 patients remained in remission at the end of the study treatment period at a corticosteroid dose equal to or below the patients' individual threshold doses at which they experienced a documented disease relapse prior to entry into the study.
Findings indicated: 1) Both lithium dose and repeated pairings enhanced development of an aversion, 2) repetition of sub threshold doses accumulated to produce an aversion, .3) an escalating dose of lithium was no more effective than repeated fixed sub threshold doses in producing an aversion, and 4) extinction of the aversion was not clearly related to either dose or repealed trials during acquisition.
For endocrine-disrupting chemicals there are no threshold doses below which exposures are safe (Sheehan 2006), a reality that regulators are unwilling to acknowledge.
The threshold doses of these 2 effects are displayed in Table 2.