1,2,3-Propanetriol, homopolymer

Endpoint summary

Additional information

Experimental data for 1,2,3-Propanetriol, homopolymer (CAS 25618-55-7) are available investigating the biodegradability of the substance. However, there are no data available for the remaining endpoints assessing the environmental fate and behavior of the substance. In order to fulfill the standard information requirements set out in Annex VI - IX, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances was conducted.

 

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 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. The assumption of similar environmental behavior of the reference substances and the target substance is supported by very similar water solubilities, log Kow values and vapour pressures (listed in Table 1), which are the most relevant physico-chemical properties for the environmental behavior of a substance.

In addition, QSAR calculations for the main components (reference substances 2-5) of the target substance were used to support the experimental data for the read across substances.

 

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

	Target	Reference 1	Reference 2	Reference 3	Reference 4	Reference 5
CAS No	25618-55-7	-	56-81-5	59113-36-9	56090-54-1	56491-53-3
EC/List No	-	915-741-3 (List No)	200-289-5	261-605-5	259-986-8	310-131-8
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	Diglycerol	Triglycerol	Tetraglycerol
MW	92.09 – 314.34	166.18 – 314.34	92.09	166.18	240.26	314.34
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%	Not applicable (only QSAR calculation)	Not applicable (only QSAR calculation)	Not applicable (only QSAR calculation)
Water solubility	Experimental result: > 550 g/L	Experimental result: > 1000 g/L	QSAR calculation: 1000 g/L	QSAR calculation: 1000 g/L	QSAR calculation: 1000 g/L	QSAR calculation: 1000 g/L
Log Kow	Experimental result: -2	Experimental result: > -3.9 < -3.3	QSAR calculation: -1.65	QSAR calculation: -2.76	QSAR calculation: -4.09	QSAR calculation: -5.41
Vapour pressure	Experimental result: ≤ 0.047 Pa at 20 °C	Experimental result: 0.00000673 Pa at 20 °C	QSAR calculation: ~ 0.01 Pa at 25 °C	QSAR calculation: ~ 0.0004 Pa at 25 °C	QSAR calculation:  < 0.0001 Pa at 25 °C	QSAR calculation: < 0.0001 Pa at 25 °C
Hydrolysis	RA: Reference 1	Experimental result: DT50 > 1 yr (25 °C, pH 4,7,9)	--	--	--	--
Biodegradation	Experimental result: 70 -80% in 28 days	Experimental result: 60 % in 28 days	Experimental result: ca. 100% in 2 days	QSAR calculation:  Prediction: readily  biodegradable	QSAR calculation:  Prediction: readily  biodegradable	QSAR calculation:  Prediction: readily  biodegradable
Bioaccumulation	Waiving based on log Kow	--	--	--	--	--
Adsorption	RA: Reference 1 RA: Reference 2 RA: Reference 3 RA: Reference 4 RA: Reference 5	Experimental result: Koc < 10.82	QSAR calculation: Koc = 1 (MCI)	QSAR calculation: Koc = 10 (MCI)	QSAR calculation: Koc = 10 (MCI)	QSAR calculation: Koc = 10 (MCI)

 

Lack of data for a given endpoint is indicated by “--“.

 

Based on the available data for the substance itself and for read-across substances and main components of the target UVCB substance, 1,2,3-Propanetriol, homopolymer (CAS 25618-55-7) is readily biodegradable according to OECD criteria. This assumption is supported by the QSAR calculations for the main components (mono- to tetra-glycerol) using BIOWIN v4.10. Ready biodegradability was predicted for all of these main components with expected biodegradation timelines of days to weeks (BIOWIN 3). Thus, it is not expected that one of the main components is persistent.

 

Since no studies investigating the abiotic hydrolysis of 1,2,3 -Propanetriol, homopolymer (CAS 25618-55-7) are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read across to 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 (List No. 915-741-3) was conducted. The half-life time of the major constituents in Polyglycerol-3 (diglycerol and triglycerol) at pH values normally found in the environment (pH 4-9) were determined to be > 1 year. Thus, the substance will slowly hydrolyze under environmental conditions. However, due to their ready biodegradability, hydrolysis is not expected to be a relevant degradation pathway for this substance.

 

1,2,3 -Propanetriol, homopolymer (CAS 25618-55-7) is water soluble (> 550 g/L) and has a low log Kow value (log Kow = -2) assuming a low adsorption potential. This assumption is supported by experimental data for a read across substance and QSAR calculations for its main components. Thus, the substance will tend to be mainly distributed into the water phase if entering the environment. However, as the substance is considered to be readily biodegradable, persistence in this compartment is not expected.

 

Bioaccumulation in aquatic organisms is unlikely since the substance has a low log Kow of -2, which assumes that the substance will not cross biological membranes. If ingested and absorbed by fish, 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).

 

Reference

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