Absorption, Distribution, Metabolism, and Excretion of Chemicals

Toxicokinetics (driven by adsorption, distribution, metabolism, and excretion, or ADME) is the primary determinant of differences in body burden, target tissue 

Absorption is the process for which most is known about the influence of specific chemical properties. Nichols et al. [56] reviewed the literature and summarized the chemical properties and approaches to their assessment that appear to dominate adsorption (and metabolism) processes in fish. These properties and predictive tools could be used as guidance in the design of compounds with the potential for reduced likelihood of ecological effects, specifically bioconcentration and bioaccumulation. 

They found that with regard to absorption, which is primarily passive in fish, compounds that are ionized are less likely to be taken up than neutral compounds, and that increased bioavailability was a function of molecular weight ( 500), logPe/w ( 5), H-bond acceptors ( 4—5), and H-bond donors ( 7-10) based on drug design from Lipinski s rule of five [57, 58]. de Wolf et al. [59] recommended that compounds with a molecular length of 4.3 nm indicates no uptake or bioconcen- 

When considering the potential for ecological impacts, understanding exposure is vital. Without exposure (whether release to the environment is intentional or not), there is no risk to ecosystems, regardless of the toxicity of the chemical. Therefore, mitigating possible exposure to toxic compounds, whether through chemical design 

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Pharmacokinetics—The science of quantitatively predicting the fate (disposition) of an exogenous substance in an organism. Utilizing computational techniques, it provides the means of studying the absorption, distribution, metabolism and excretion of chemicals by the body. 

Pharmacokinetic The quantitative study of factors that control the time course for absorption, distribution, metabolism, and excretion of chemicals within the body. 

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