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No reliable studies available.

The following remarks on the toxicokinetics of naphthalene-1,5-diamine are based on the studies reported within this dossier. Experimental toxicokinetic studies have not been performed. Naphthalene-1,5-diamine is a solid with a very low vapour pressure under normal ambient conditions (5 x 10EE-8 hPa at 25 °C). Vapour inhalation, therefore, is an unlikely route of exposure.

The log Pow of 0.91 is low, not favorable for absorption after inhalation exposure. In an acute inhalation experiment the LC50 was reported to be >5.27 mg/l and symptoms of toxicity observed were: reduced motility, decelerated beathing, ruffled hair (occurred in the second half of the first week of the observation period); 2 females died after 4 days; macroscopical findings in female rats: hydrothorax, reddened renal pelvis, dark and enlarged spleen, pale liver with marked lobules, reddened gastrointestinal tract. The physico-chemical characteristics of naphthalene-1,5-diamine (soluble in water at 0.27g/L at 20 °C; log Pow of 0.91) and the molecular mass of 158 g/mol are in a range suggestive of some absorption from the gastro-intestinal tract subsequent to oral ingestion. The assumption of an oral absorption is confirmed by systemic toxicity observed in acute toxicity and repeated dose toxicity studies in rats and/or mice with exposure up to 2 years.

The n-octanol/water partition coefficient of naphthalene-1,5-diamine is in a range which dose not favor dermal absorption. This is supported in a study assessing the acute dermal toxicity of naphthalene-1,5-diamine to rats, where no systemic or local symptoms of toxicity were observed at 2000 mg/kg bw.

As a small molecule with the given water solubility a wide distribution is expected. This assumption is confirmed by the variety of effects shown in the oral repeated dose toxicity study.