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Assessment of Toxicokinetic Behaviour

Hexaoxatricosane (CAS-No. 143-29-3) 

There were no studies available in which the toxicokinetic properties of hexaoxatricosane were investigated.

 

1. Phys-Chem properties of the substance

Hexaoxatricosane (molecular weight of 336.5 g/mol) is a yellow colored liquid, which is soluble in water(measured water solubility: 16.8 g/l at 20 °C (BASF 2008, see chapter 4.8 water solubility).The calculated log Po/w is 1.65 at 25 °C (BASF 2007, see chapter 4.7 partition coefficient), indicating that a general accumulation of hexaoxatricosane is possible.

2. Adsorption/Distribution/Metabolism/Excretion (ADME)

Absorption

In acute oral toxicity studies, rats were administered hexaoxatricosane by gavage. In all two studies mortalities and clinical signs of toxicity were observed in doses of 2000 mg/kg bw and higher (Longobardi, 2003; Shelanski, 1958, see chapter 7.2.1 acute oral toxicity). Signs of toxicity of hexaoxatricosane or its metabolites were also reported in the MN test in vivo in CD-1 mice from the high treatment group (1500 mg/kg bw) under the test conditions (Getuli, 2003; see chapter 7.6.2 genetic toxicity in vivo).

Therefore, bioavailability of hexaoxatricosane after oral administration is indicated.

In acute dermal toxicity studies a single dose level of 2000 mg/kg hexaoxatricosane was administered to rats (Longobardi, 2004). No clear signs of systemic toxicity were observed, indicating primarily a low dermal toxicity. Due to the experimental low acute oral and dermal toxicity, no assessment of the dermal absorption potential of hexaoxatricosane in humans can be made. Calculations of the dermal absorption potential of the substance (Kp value) using DERMWIN (v. 2.00) indicate a very low dermal absorption potential.

Hexaoxatricosane has a comparably low vapour pressure of 1.064E-5 hPa at 20°C (BASF 2001, see chapter 4.6 vapour pressure); subsequently, the calculated vapour saturation threshold is ca. 0.0412 mg/L. Additionally, the calculated Henry constant of ca. 1.65E-6 Pa*m3/mole indicates that the substance would not evaporate from water surface into the atmosphere so that an exposure via atmosphere is not expected. Therefore, absorption of the substance via the inhalative route is not assumed.

 

During exposure clinical signs were observed which disappeared after removal the animals from chamber. No necropsy findings were observed, indicating a low potential of toxicity of the substance via the inhalative route.

 

Metabolism

In a subacute study rats only showed a treatment-related increase in liver weight after repeated application of the high dose (800 mg/kg bw/day) over 43 days (RTC 2004). Treatment-related organ weight changes occurred in the liver of high dose males and females. Additionally, potential metabolites were calculated by OECD toolbox 1.00. Here, the liver metabolism simulator provided 140 potential metabolites e.g. 1-butanol (CAS No. 71-36-3), n-butylaldehyde (CAS No. 123-72-8), butanoic acid (CAS No. 107-92-6), diethylene glycol mono butylether (CAS 112 -34 -5), ethylene glycol mono buthyl ether (CAS 111-76-2), glycolic acid (CAS No. 79-14-1), formic acid (CAS 64-18-6) and 145 others (see attached document).

These metabolites were not calculated as potential metabolites in the respective simulator for the GI tract and the skin, respectively. Furthermore, no hydrolysis could be reported (see IUCLID chapter 5.1.2) . A treatment-related effect on fertility was apparent in the high dose group.

Studies on genotoxicity (Ames-Test, HPRT, micronucleus assay in-vivo with a single oral dose (gavage) up to 1500 mg/kg bw) were negative.

Excretion

 

The potential metabolites named above have at least a lower molecular weight than 300 u and good water solubility is expected. Therefore, hexaoxatricosane and its metabolites are expected to be excreted predominantly via the urine.