Stress pathway

Type of pathway used in intracellular signaling. Stress pathways are induced when a disruption of normal cell function and development occurs due to physical or chemical agents of the environment. Induction of stress pathways leads to cellular repair and counteraction.


The process by which a toxicant enters an organism, how it reacts with target molecules, how it exerts its deleterious effects, and how the organism reacts to the insult.


The study of how a toxic chemical (or metabolites derived from it) interacts with specific molecular components of cellular and, in the context of this report, developmental processes in the body.


The study of how a toxic chemical is absorbed, distributed, metabolized, and excreted into and from the body.

Transcription factor

A DNA binding protein that is involved in the formation of mRNA.


Any animal whose genome has been altered by addition of genetic material or by alteration of existing genes by gene targeting.

Uncertainty factor (UF)

One of several factors used in calculating an exposure level that will not cause toxicity from experimental data. UFs are used to account for the variation in susceptibility among humans, the uncertainty in extrapolating from experimental animal data to humans, the uncertainty in extrapolating from data from studies in which agents are given for less than a lifetime, and the uncertainty in using LOAEL data instead of NOAEL data.

Wild type

The normal or usual allele or phenotype. In cases in which multiple allelic variants have a normal phenotype, the wild-type allele is usually considered the most common one.


An embryo newly formed as a result of fertilization.

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