Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics
Type of information:
other: Assessment of the toxicokinetic behaviour as can be derived from the available information.
Adequacy of study:
weight of evidence

Data source

Reference
Reference Type:
study report
Title:
Unnamed

Materials and methods

Principles of method if other than guideline:
Review of reports summarised in the dataset

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
Given the low vapour pressure, it is unlikely that inhalation of the vapour will occur.
2,2’-oxydiethanol, ethoxylated and propoxylated (>1<4.5 EO and >1<4.5 PO) (the NLP polyol) contains very little material of the molecular size that may result in significant lymphatic absorption. Thus the principal mechanism of absorption for these NLP polyols is passive diffusion. Given that the trimer of propane-1,2-diol, propylene-1,2-diol + 2PO, is well absorbed, the molecule representing the mean toxicity is probably also absorbed when administered orally.
Given the logP and the fact that propane-1,2-diol can be absorbed when co-administered with oleic acid it is likely that the oligomers are absorbed dermally.
Details on distribution in tissues:
Given the logP values, it is likely that oligomers of 2, 2’-oxydiethanol ethoxylated and propoxylated will be widely distributed in body water and it is unlikely that they will accumulate in tissues.
Details on excretion:
In rat, some higher molecular weight material may be excreted in bile. In rat the molecular weight threshold for biliary excretion is around 350 Daltons and some material from the highest no longer polymers may just exceed this threshold. In humans the threshold is about 500 (Illing, 1989), thus it would be expected that little, if any, of the NLP polymer would be excreted in human bile. Once the material has been hydrolysed, the products below the appropriate threshold will appear in urine, except when the end point of the product is carbon dioxide. Carbon dioxide will be exhaled.

Metabolite characterisation studies

Details on metabolites:
Based on the information on the repeating unit and trimer, it is likely that the oligomers will be stepwise hydrolysed across the ether linkage and the three carbon elements metabolised to lactic acid/pyruvic acid and taken into intermediary metabolism.

Any other information on results incl. tables

There are no experimental studies on the toxicokinetics of ethoxylated and/or propoxylated ethane-1,2-diol or ethoxylated and/or propoxylated 2,2’-oxydiethanol. The toxicokinetics of the core substances and the repeating unit are summarised in Illing and Barratt (2007 revised 2009). Both core substances have two free hydroxy groups, thus NLP polyols are likely to consist predominantly of chains of between one and two repeating units, with some chains containing three repeating units.

For the calculations of bioavailability of the commercial NLP polyol, logP values were calculated using the incremental fragment method of Suzuki and Kudo (1990). The propoxy groups have an important effect on the toxicity by modulating any toxicity arising from the core substance. The substitution of a hydroxyl group on a core compound by a propoxy group increases its logP value by 0.24 units and its molecular weight by 58. The combined effect of these changes is to reduce the bioavailability by a factor of 1.53 (calculated using the Potts and Guy equation). Similar extrapolations can be performed for ethoxylated and ethoxylated and propoxylated side chains (see Illing and Barrat, 2007 revised 2009).

Applicant's summary and conclusion