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Annex XI of Regulation 1907/2006 and the REACH Guidance (R 6.2) permits the grouping of chemicals (chemicals categorisation).Barratt and Illing (2007, revised 2009a; 2009b, see attachmentsin section 13 of IUCLID data set) set out justification for an initial grouping of the polyols (oligomers and polymers) using a named core substance, with varying numbers of attached propoxy groups (or propoxy and ethoxy groups). The properties of the core substance and the repeating unit should be reflected in the polyols. The repeating unit is essentially non-toxic. If there are toxic properties associated with a core substance, these properties should reduce with increasing numbers of repeating units (i.e. increasing molecular weight).If both the core substance and the repeating unit are non-toxic, it can be anticipated that there will be no toxicity in the polyol.

 

A second round of grouping was based on allocation of the NLP polyols formed from different named core substances to one of two categories. The first group was those NLP polyols linked to the core substance by an ether linkage (category 1) and the second group (category 2) was those linked by a secondary/tertiary amine linkage.

Category 1 consists of:

·        Sucrose, propoxylated, >1-16.5 moles propoxylated

·        propylidyne trimethanol, propoxylated, >1-6.5 moles propoxylated

·        Glycerin, propoxylated, >1-6.5 moles propoxylated

·        Propan-1,2-diol, propoxylated, >1-4.5 moles propoxylated

·        Pentaerythritol, propoxylated, >1-8.5 mol propoxylated.

·        Nitrilotriethanol, propoxylated, 1-6.5 moles propoxylated.

For details see attached documents ‘Grouping of NLP Polyols and their toxicokinetics assessments’ (Barratt and Illing (2007, revised 2009a) and PROPOSALS FOR FURTHER TESTING FOR THE NLP ‘POLYOLS’ (2009b) in section 13 of IUCLID data set. 

The registered substance is a complex substance (UVCB) which can be regarded as a mixture of Sucrose, PO and Glycerin, PO, two members of the grouping "NLP polyols linked to the core substance by an ether linkage" (= category 1). As, in all cases, the ether linked NLP polyols are non-toxic, it is anticipated that any mixture of them or any co-initiated polyol formed using a mixture of initiators will have a similar lack of toxicity. Thus the hazard profile for the multicomponent substance can be sufficiently described by the information of the individual constituents and it is unnecessary to test these co-initiated NLP polyols. The physico-chemical properties of these source substances and the target substance are very similar as displayed in Table 1.

Table 1: Comparison of physico-chemical properties of source substances with target substance

 

 

Source Substances

Target Substance

 

Glycerin + PO

Sucrose + PO

Glycerin + Sucrose + PO

Appearance

liquid

liquid

liquid

Melting point

no MP

no MP

no MP

Boiling point

Decomposition >= 290°C

no BP

Decomposition >= 210°C

Relative density

1.08 (20°C)

1.122 (20°C)

1.132 (20°C)

Partition coefficient

> -1.82 < -0.73

> -3.60 < -3.25

> -0.7 < 1.1

Water solubility

completely miscible

240 g/L (25°C)

completely miscible

Surface tension

53 nM/m (20°C; at 1 mg/L)

54.54 nM/m (20°C; at 1 mg/L)

61.3 nM/m (20°C; at 1 mg/L)
(Glycerol + PO)

Flashpoint

163°C (no information on pressure available)

149.5°C (1003 hPa)

198°C (1013 hPa)

Auto flammability

305°C (1014 ha)

355°C (1000 hPa)

350°C (1008 hPa)

Flammability

no pyrophoric properties
does not emit flammable gases in contact with water

no pyrophoric properties
does not emit flammable gases in contact with water

no pyrophoric properties
does not emit flammable gases in contact with water

Explosiveness

no explosive properties

no explosive properties

no explosive properties

Oxidising properties

no oxidising properties

no oxidising properties

no oxidising properties

Viscosity

560.6 mPa (20°C)

26.63 Pa s (20°C)

21.47 mPa s (20°C)

Therefore, in line with Annex XI, 1.2 of Regulation (EC) No 1907/2006, read-across (many-to one) was chosen for the registered substance (Polyether Sucrose + Glycerin+ PO) and thus no toxicological study has been performed with registered substance itself.

The model being used to justify read-across (many-to one) is that the toxicity of the polyether polyol is derived from the core substance (initiator) and the repeating unit. While for propoxylated polyols the repeating unit is probably not classifiable, any toxicological property requiring classification is derived from the core substance. The fact, that the target chemical is formed from core substances (Sucrose and Glycerin) which are the same for two source substances (Sucrose, PO and Glycerin, PO), suggests that there are no major differences between these source substances and the target substance which may affect the toxicological properties. Due to the closeness of the compounds, polyols grouping data (= source substances data) is lead for Polyether Sucrose + Glycerin + PO (= target substance) according to Table 2 (see section 13 of IUCLID data set).

Toxicokinetic Assessment - read-across with other polyols linked to the core substance by an ether linkage:

"Sucrose, propoxylated, 1-16.5 moles propoxylated is a relatively non-volatile liquid at room temperature (Vapour pressure 2 hPa at 20oC) . The commercial material is soluble in water (240 g/L) and has a log P of<0.5. It is essentially non-toxic.

 

There are no studies on the toxicokinetics of sucrose, propoxylated, 1-16.5 moles propoxylated. The approach employed in this toxicokinetics assessment is to examine data for the repeating unit and initiating agent, sucrose, and NLPs made using sucrose as initiating agent and 1-methyl-2-oxirane as the chain-lengthening agent (in ascending order of multiples of the repeating unit). The data therefore comes from studies on sucrose, propane-1,2-diol, and oligomers of propane-1,2-diol. Some additional information is available from the fatty esters of sucrose used as substitutes for dietary fat. Conclusions for the longer oligomers are based on those data and on structure activity information." (cited from Illing, H P A, Barratt, M D (2007, revised 2009a). Grouping of NLP ‘Polyols’ and their Toxicokinetics Assessments. Confidential report to the European Diisocyanate and Polyols Producers Association. December 2007, revised 2009a.)

Glycerol, propoxylated is an essentially non-volatile liquid (vapour pressure 6 x 10-2 hPa at 20ºC), at room temperature, fully miscible with water and with a log P of 1.0 – 1.6 (as measured on commercial material). There are no experimental studies on the toxicokinetics of propoxylated glycerol. The information on the toxicokinetics of glycerol, propoxylated, 1-6.5 mol and higher oligomers is based on the information for glycerol and for propane-1, 2-diol (propylene diol) and oxydipropanol and [(methylethylene)bis(oxy)]dipropanol. Additional information is derived from studies on the absorption of hydrocarbons and the acute toxicity data for higher molecular weight polyols that use glycerol as initiator.

Discussion on bioaccumulation potential result:

There are no experimental studies on the toxicokinetics of target and source substances. Sucrose (the core substance) and propane-1,2-diol and oligomers (the propoxylated side chains) are possible models for the absorption of the propoxylated sucrose. Sucrose has eight free hydroxy groups, thus oligomers are likely to consist of chains of between one and three monomers.

 

Sucrose is unlikely to be absorbed by passive diffusion, but, if absorbed by passive diffusion, absorption would be in the stomach and upper intestine where the alcohol groups are unionised. Sucrose is hydrolysed in the brush border of the intestine and the two monosaccharides, fructose and glucose, and these carbohydrates are absorbed by active transport. Propane-1,2-diol and [(methylethylene)bis(oxy)]dipropanoloxydipropanol are absorbed when administered orally, probably by passive diffusion. Essentially, the propoxylated sucrose is non-toxic. (partly cited from Illing, H P A, Barratt, M D (2007 revised 2009a). Grouping of NLP ‘Polyols’ and their Toxicokinetics Assessments. Confidential report to the European Diisocyanate and Polyols Producers Association. December 2007, revised 2009a.)

Glycerol is solely a core substance (initiator). However, it is structurally related to propane-1,2-diol (both are C3) and there are similarities in the metabolism of fatty acid esters of both substances by the intestine. There are three free alcohol groups available for formation of the NLP polyols, so the likelihood is that the side chains will be mainly of one or two units, with some of three units. The information on the toxicokinetics of glycerol, propoxylated, 1-6.5 mol (the NLP polyol), and higher oligomers/polymers generally, is based on the information for glycerol, for triglycerides (fats) and for propane 1,2-diol and oligomers. Additional information is derived from studies on the absorption of hydrocarbons. There is some further information in Patty which has also been incorporated into this assessment. In addition, some predictions can be made from the physicochemical and toxicological information on the oligomers