Study Set Content:
Factors whether a toxic response would occur:
Chemical and Physical properties of the chemical Exposure scenario Metabolism Concentration of the active form at the target site/s Overall susceptibility
Route and Site of exposure the () route is the greatest and has the most rapid response.
IV
Duration and Frequency of Exposure experimental animals to chemicals is classified according to four categories:
acute, subacute, subchronic, and chronic.
In human exposure situations there are only 3 categories:
Acute, Subchronic, Chronic
occurring from a single incident or episode
Acute exposure
occurring repeatedly over several weeks or months
Subchronic exposure
occurring repeatedly for several months or years
Chronic exposure
The relationship between the “dose” and “response” to a chemical is the foundation of modern toxicology.() relationships are defined as the association between the amount of a toxicant administered and the extent to which changes are observed in a biological system
Dose– response
dose of the chemical administered or measured in the environment.
External dose
amount of chemical absorbed and found at the site of biological activity.
Internal dose
Describes the response of an individual organism with varying doses. Dose-related increase with severity of the response
INDIVIDUAL – “GRADED” DOSE-RESPONSE RELATIONSHIP
Characterizes the distribution of responses to different doses in a population
POPULATION – QUANTAL DOSE-RESPONSE RELATIONSHIP
The dose–response relationships in a population are by definition quantal—or “all or none”—in nature; that is, at any given dose, an individual in the population is classified as either a
“responder” or a “nonresponder.”
widely used approach for estimating the response of a population to a toxic exposure.
Effective dose (ED)
death is the measured endpoint, the ED50.
Lethal dose (LD)
minimal ED of any chemical that evokes a stated all-or-none response.
Threshold dose
Response is due to the
Chemical Administered
The Magnitude of the Response is Related to the
Dose
There Exists Both an Appropriate Method of Quantifying and a Precise Means of Expressing the
Toxicity
Ratio of the dose required to cause a toxic effect to the dose needed to produce the desired therapeutic response.
Therapeutic Index
