Tattoos have seen an increase in popularity over the last decades with reports of a prevalence of around 20% in European countries, the U.S. even higher [1]. The inks used for tattooing are very diverse in their composition and may contain harmful chemicals such as heavy metals [2]. To support assessing the health risks from tattooing, it is crucial to know the internal exposure to compounds of the ink. For this aim, a recent study performed experiments with iodide as a marker substance added to the tattoo ink to approximate the uptake of metals [3].
Here, a physiology-based kinetic (PBK) model (Fig. 1A) is used to describe experimental plasma concentration data and simulate the distribution of iodine in the body and its excretion by optimizing parameters for each of the 22 participants (Fig. 1B). To this end, an existing model [4] was extended to account for dietary iodine and the iodide uptake by tattooing; moreover, a reabsorption process of iodine in the kidney was introduced upon observing a high discrepancy between urine data and model simulations. We are able to show that the fraction of iodine which was systemically available varies widely (10 – 90%) within the group of subjects undergoing tattooing (Fig. 1C). The results may support risk assessment of metals and ions present in inks.
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Fig. 1 A) Extended PBK model for iodine with parameters in 1/d, B) parameter fitting for a subject based on experimental data, and C) variation in systemic fraction (Fsys) of iodine within group of subjects.