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Key value for chemical safety assessment

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There were no studies available in which the toxicokinetic properties of the test substance were investigated. The test substance (molecular weight of 358 g/mol) is a yellow powder with a log Pow of 5.02 and a water solubility of 4.7 µg/L at 23°C. The vapor pressure was estimated at 1.3E-009 Pa at 25°C.

In an acute toxicity study in rats no mortality and no systemic findings were observed after oral administration of test substance at a dose level of 6400 mg/kg body weight. Therefore, no conclusion can be drawn regarding systemic distribution. Generally, the smaller the molecule, the more easily it may be taken up. Molecular weights below 500 g/mol are favorable for absorption; molecular weights above 1000 g/mol do not favor absorption (ECHA GD 7c, 2008). The test article is characterized by a molecular weight in a range supporting absorption in the gastrointestinal tract. The water solubility of the test article is low, thus not favoring the substance to be readily dissolved in gastrointestinal fluids. The findings reported in an OECD 422 study demonstrates that the substance is taken up and bioavailable. In this study, adverse findings were reported in the high dose level indicating that the substance has been absorbed. In addition, discoloration of adipose tissue was reported, obviously corresponding with duration of treatment and dose level since low-dose male animals did not show the discoloration (treated for 4 weeks), but females did (treated for about 8 weeks). These observations support the hypothesis of systemic bioavailability and lead to the conclusion that the test substance accumulates by time and dose. Therefore, absorption through the gastrointestinal tract has occurred. A sensitization study was negative, therefore not allowing for a conclusion regarding dermal absorption. The vapor pressure is very low therefore absorption by inhalation is considered less relevant. The excretion pathway is largely dependent on molecular size, polarity and water solubility. Potential metabolites are either excreted via feces or urine, depending on their molecular size and water solubility after phase II metabolism.