# Bio-elimination

Bio-elimination of ENMs indicates the process whereby nanomaterials are excreted from an organism’s body. This elimination can occur in different forms, and depends entirely on:

• the type of ENM
• the internal concentrations of the ENMs in the organism
• the physiology of the organism

It is assumed that external concentrations of ENMs do not affect the rate of elimination.

## Occurs in  ## Algorithms Elimination curve when organism has been moved to clean medium (on day 50) (conceptual graph of exposure experiment) Elimination rate constantk2 (day-1) Elimination takes place together with uptake in contaminated media [equation 1]. Elimination also occurs in clean media, whereas no actual uptake takes place there [equation 2]. Elimination of a single form of the ENM is calculated below. 1. Elimination when exposed in contaminated medium $$C_{org}= C_{env} \ast k_{1}\ast SF \ast t + C_{env} \ast \frac{k_{1}}{k_{2}+k_{g}}\ast (1-e^{-(k_{2}+k_{g})\ast t})(1 - SF)$$ 2. Elimination when exposed in clean medium after tm days in contaminated medium $$C_{org}= C_{env} \ast k_{1} \ast SF \ast t_{m} + C_{env} \ast \frac{k_{1}}{k_{2}+k_{g}}\ast (1-(e^{-(k_{2}+k_{g})\ast t}\ast e^{-(k_{2}+k_{g})\ast(t-t_{m})})\ast (1-SF)$$ Where:  $$C_{org}$$ - Concentrations in the organism ($$\mu g/g$$)$$C_{env}$$ - Concentrations in the environmental compartment ($$\mu g/g$$)$$k_{1}$$ - uptake rate constant (g*g-1* day-1)$$k_{2}$$ - elimination rate constant (day-1) $$k_{g}$$ - growth dilution constant (day-1) $$SF$$ - stored fraction ($$0\leq SF\leq 1$$) (unitless) $$t$$ - total time of experiment (day) $$t_{m}$$ - time of transfer from contaminated to clean soil (day)   Visit the Uptake, elimination and growth dilution page.

 Visit the NanoFASE Library to read summaries of these reports: NanoFASE Report D9.2 Loureiro et al. Parameter sets on uptake and toxicokinetics of selected pristine NMs in aquatic and terrestrial organisms Baalousha et al. 2016. Environ Sci Nano 3, 323-345.Cornelis, G. et al., 2014. Crit Rev Environ Sci Technol. 44: 2720–2764Ardestani et al. 2014. Environ. Poll 193, 277-295. Baalousha, M. et al. 2016. Modeling nanomaterial fate and uptake in the environment: current knowledge and future trends. Environ Sci Nano 3, 323-345. DOI: 10.1039/c5en00207a Cornelis, G. et al. 2014. Fate and Bioavailability of Engineered Nanoparticles in Soils: A Review. Crit Rev Environ Sci Technol 44, 2720–2764. DOI: 10.1080/10643389.2013.829767 van den Brink, N.W. et al. 2019. Tools and rules for modelling uptake and bioaccumulation of nanomaterials in invertebrate organisms. Environ Sci Nano 6, 1985-2001. DOI: 10.1039/C8EN01122B

## Contact Nico van den Brink   Email: Nico.vandenbrink@wur.nl Kees van Gestel   Department of Ecological Science  Faculty of Science, Vrije Universiteit   Email: kees.van.gestel@vu.nl