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The substance is readily biodegradable. In addition, the log Kow is below 3 and the substance has no cationic properties, a low adsorption potential is indicated. Therefore, binding to sewage sludge is unlikely and as a consequence a transfer to the soil compartment is not expected. Therefore, no tests on terrestrial organisms are provided.

Furthermore, considering all available ecotoxicological data from the substance itself and read across substances combined in an expert statement as presented below the substance is unlikely to pose a risk to terrestrial organisms in general.

 

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 whereby physicochemical, toxicological and ecotoxicological properties may be predicted from data for reference substance(s) by interpolation to other substances on the basis of structural similarity, the two substances listed in Table 1 are selected as reference substances and the available endpoint information is used to predict the same endpoints for 1,2,3-Propanetriol, homopolymer (CAS 25618-55-7).

A read across from the source substances in order to assess the environmental fate and aquatic toxicity of 1,2,3-Propanetriol, homopolymer (CAS 25618-55-7) is considered valid, since the reference substances represent the main components of the target substance. The only differences are i) the slightly different proportional composition of these components and ii) the absence of mono-glycerol, a main component of the target substance but not part of reference substance 1. Therefore, data for mono-glycerol (reference substance 2), although listed in Annex V of Regulation (EC) No. 1907/2006 and thus exempted from registration, are considered additionally. Based on the fact that the components of the reference substances and the target substance are identical the functional groups (hydroxyl groups) and the metabolites are expected to be identical as well.

 

Table 1: Data for the target substance and the two considered reference substances

 

Target

Reference 1

Reference 2

CAS No

25618-55-7

-

56-81-5

EC/List No

-

915-741-3 (List No)

200-289-5

Chemical Name

1,2,3-Propanetriol, homopolymer

Reaction mass of 3-[3-(2,3-dihydroxypropoxy)-2-hydroxypropoxy]propane-1,2-diol,3-(2,3-dihydroxypropoxy)propane-1,2-diol,3-[3-[3-(2,3-dihydroxypropoxy)-2-hydroxypropoxy]-2-hydroxypropoxy]propane-1,2-diol

Glycerol

MW

92.09 – 314.34

166.18 – 314.34

92.09

Composition

mono-glycerol: 33.3 %

di-glycerol: 28.49 %

tri-glycerol: 15.48 %

tetra-glycerol: 8.33 %

di-glycerol: 15-35 %

tri-glycerol: 35-55 %

tetra-glycerol 10-25 %

>80%

Water solubility

Experimental result:

> 550 g/L

Experimental result:

> 1000 g/L

QSAR calculation:

1000 g/L

Log Kow

Experimental result:

-2

Experimental result:

> -3.9 < -3.3

QSAR calculation:-1.75

Vapour pressure

Experimental result:

≤ 0.047 Pa at 20 °C

Experimental result:0.00000673 Pa at 20 °C

QSAR calculation:

~ 0.1 Pa at 20 °C

Aquatic ecotoxicity data

Short-term aquatic toxicity data for the reference substances are available for all trophic levels. Long-term data is available for aquatic algae. Based on the experimental data, it can be considered that 1,2,3-Propanetriol, homopolymer (CAS 25618-55-7) exhibits no toxicity to aquatic organisms up to the highest tested concentration of 500 mg/L (fish) and 1000 mg/L (daphnia, algae), respectively. The substance is thus not expected to pose a risk to terrestrial organisms as well.

 

Metabolisms/Bioaccumulation

The low log Kow value of -2indicates only a low bioaccumulation potential of 1,2,3-Propanetriol, homopolymer (CAS 25618-55-7). If ingested and absorbed, the mono-glycerol component is expected to be rapidly metabolised via cleavage of the ether bond as shown by Saunders & Dawson (1962) and Haessler & Isselbacher (1963) in rats and hamster. In contrast the polyglycerols are not expected to be catabolized but excreted rapidly into the urine after absorption as shown, for example, for triglycerol and polyglycerol (C10) by Michael and Coots (1971).

 

Conclusion

1,2,3-Propanetriol, homopolymer (CAS 25618-55-7) is unlikely to pose a risk for terrestrial organisms based on a) the lack of direct exposure based on identified uses, b) lack of indirect exposure due to ready biodegradability and low log Kow and thus low adsorption potential and c) rapid excretion and metabolism via common pathways, leading to expected low bioaccumulation potential and low toxicity.

 

Reference

ECHA (European Chemicals Agency). 2012b. Guidance on information requirements and chemical safety assessment. Chapter R7.b: Endpoint specific guidance, version 1.2 (November 2012), Helsinki, Finland

Haessler HA, Isselbacher KJ. 1963. The metabolism of glycerol by intestinal mucosa. Biochem Biophys Acta 73(3): 427 -436

Michael WR, Coots RH. 1971. Metabolism of polyglycerol and polyglycerol esters. Toxicol Appl Pharmacol 20(3): 334 -345

Saunders DR, Dawson AM. 1962. Studies on the metabolism of glycerol by the small intestine in vitro and in vivo.Biochem J 82(3): 477 -483

e in vitro and in vivo. Biochem J 82(3): 477 -483