Reaction products of D-Glucose, n-Butanol and C10-12 (even numbered) alcohols

Endpoint summary

Additional information

The Alkyl Polyglycosides Category contains D-Glucopyranose monomers and oligomers with fatty alcohols C4 to C18 linear or in several cases (C9 to C11) mono-branched. Structural similarities of the category substances are reflected in similar physico-chemical properties and mode of action. Alkyl polyglycosides have a common metabolic fate that involves hydrolysis of theα- and ß-glycosidic bond to the fatty alcohol and glucose. Glucose and glucose oligomers enter the carbohydrate metabolic pathway and are catabolised. Fatty alcohols, representing the main difference in the structure of different alkyl polyglycosides, are oxidized to the corresponding fatty acid and fed into physiological pathways like the citric acid cycle, sugar synthesis and lipid synthesis.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met. In particular for human toxicity, environmental fate and eco-toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across)”. Therefore, the available experimental data were collected and evaluated according to Annex XI in regard to:

-      Test duration (only tests which cover the expected exposure duration were regarded as suitable)

-      Key parameters of the test (only tests that cover the key parameter were accepted as suitable)

-      Comparability of the test systems

-      The adequacy of the results for C&L

-      The documentation of the test procedures (only in case of good documentation data)

Only data that were judged to cover the requirements specified above were used as adequate data suitable for the category and its members. In this particular case the similarity of the Alkyl Polyglycosides Category members is justified, in accordance with the specifications listed in Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of substances and read across, on basis of scope of variability and overlapping of composition, representative molecular structure, physico-chemical properties, toxicological, ecotoxicological profiles and supported by various QSAR methods. There is no convincing evidence that any one of these respective chemicals might lie out of the overall profile of this category. The key points that the members share are:

(i)              Common origin: produced from fatty alcohols, reacting with D-glucose in the presence of an acid catalyst.

(ii)             Similar structural features: aliphatic hydrocarbon chain bound to glucose oligomers by alpha or beta glycosidic bond.

(iii)            Similar physico-chemical properties: trend in log Pow based on alkyl chain length and degree of glycosylation; low vapour pressure; water solubility decreasing with the alkyl chain length, starting from very high and high values up to insoluble C16-18; surface active substances fully dissociated in water (exception: C16-18).

(iv)           Common properties for environmental fate & eco-toxicological profile: readily biodegradable, no potential for bioaccumulation, low to moderate adsorption potential, clear trend in aquatic toxicity (increasing toxicity with increasing carbon chain with a maximum at C12-16 and then decreasing), no potential for sediment and soil toxicity.

(v)            Similar metabolic pathways: absorption in the intestine, hydrolysis of theα- andβ-glycosidic bond in intestine and further metabolism of the breakdown products sugar and alcohol. Alkyl polyglycosides withα-glycosidic bond may already be hydrolysed in the saliva by enzymatic activity ofα-amylases.

(vi)           Common levels and mode of human health related effects: The skin and eye irritating properties of the alkyl polyglycosides represent the main factor for effects on human health. The similar toxicokinetic behaviour (hydrolysis of theα- andβ-glycosidic bonds) results in similar cleavage products, which show a low toxicity after acute and repeated oral exposure. Furthermore, all category members are not sensitising, not mutagenic or clastogenic, and have shown no reproduction and developmental toxicity.  

For the Alkyl Polyglycosides Category, many studies are available on the short- and long-term toxicity to fish, invertebrates, and algae, microorganisms, sediment and terrestrial organisms. The results demonstrate that comparing toxicity to fish, invertebrates and algae, toxicity across the trophic levels is rather similar for the aquatic compartment. The most important influencing parameter for aquatic toxicity within the Alkyl Polyglycosides Category is the chain length of the alkyl group. The carbon chains of lengths C12-16 caused the lowest effect values whereas the chains below and above C12-16 were less or even non-toxic.

Sediment is not expected to be a compartment of concern since alkyl polyglycosides are mostly well soluble in water (except forD-Glucose, reaction products with alcohols C16-18 (even numbered) (excess)), have a low potential for bioaccumulation and are readily biodegradable. Therefore, alkyl polyglycosides will degrade in the STP process. In case of release to sediment, the substances are expected to rapidly degrade in the environment. Nevertheless, studies on sediment toxicity are available for most of the category members. Again, a trend of increasing toxicity with increasing carbon chain length could be observed, however effects only occurred at very high concentrations (LC50 values range from 650.45 mg/kg dw to > 7023.1 mg/kg dw and NOEC values range from 71.36 mg/kg dw to 698 mg/kg dw).

In case of exposure to soil, the substances are also expected to rapidly degrade, thus the hazard to terrestrial organisms is assumed to be negligible. Additionally, some studies on terrestrial macroorganisms (D-Glucopyranose, oligomeric, butyl glycoside; D-Glucopyranose, oligomeric, C10-16-alkyl glycosides) and terrestrial plants (D-Glucopyranose, oligomeric, C10-16-alkyl glycosides) are available which consistently show no effects on the test organisms.

Aquatic toxicity

Short-term fish toxicity

Short-term toxicity to fish is well studied for the category of alkyl polyglycosides and includes studies with substances ranging from D-Glucopyranose, oligomeric, butyl glycoside to D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess), covering a variety of both freshwater and marine species. Alkyl polyglycosides of chain lengths from C4 to C8-10 seem to have low to moderate toxicity, whereas substances from C9-11 to C10-16 are more toxic. Toxicity ofD-Glucose, reaction products with alcohols C16-18 (even numbered) (excess)could not be observed which can be explained by reduced bioavailability as a consequence of the low water solubility.

The 96-hour LC50 values for fish determined for alkyl polyglycosides vary from 2.95 mg/L for D-Glucopyranose, oligomeric, C10-16-alkyl glycosides up to 420 mg/L for D-Glucopyranose, oligomers, hexyl glycosides.

Short-term toxicity to aquatic invertebrates

The influence of the chain length of alkyl polyglycosides on the acute fish toxicity is comparable to that on invertebrate toxicity. Also in this case a clear correlation can be shown between the toxicity of alkyl polyglycosides and the carbon chain length; the available experimental database includes studies on alkyl polyglycosides ranging from D-Glucopyranose, oligomeric, butyl glycoside to D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess). Short-term toxicity to aquatic invertebrates increases with increasing length of the hydrocarbon chain up to C16 and then decreases.

The 48-h EC50 values for aquatic invertebrates determined for alkyl polyglycosides range from 7 mg/L for D-Glucopyranose, oligomeric, C10-16-alkyl glycosides to 780 mg/L for D-Glucopyranose, oligomers, hexyl glycosides.

Long-term fish toxicity

One long-term test on fish is available for D-Glucopyranose, oligomeric, C10-16-alkyl glycosides, with a resulting NOEC value of 1.8 mg/L. As D-Glucopyranose, oligomeric, C10-16-alkyl glycosides represents the worst case regarding acute aquatic toxicity, this study is applied for read-across to the other members of the Alkyl Polyglycosides Category. However, it should be emphasized that this represents a worst case scenario.

Long-term toxicity to aquatic invertebrates

One long-term test on aquatic invertebrates is available for D-Glucopyranose, oligomeric, C10-16-alkyl glycosides, with a resulting EC10 value of 1.76 mg/L. As D-Glucopyranose, oligomeric, C10-16-alkyl glycosides represents the worst case regarding acute aquatic toxicity, this study is applied for read-across to the other members of the Alkyl Polyglycosides Category. However it should be emphasized that this represents a worst case scenario.

For a component of D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess). (C18 fatty alcohol), there is also one study available. As a result, a NOEC (21 d) value of 0.98 mg/L was stated (mortality and reproduction). However, results above the limit of solubility should be treated with caution as they may reflect the effects of physical fouling rather than true toxicity of the test substance.

Toxicity to aquatic algae

Several reliable experimental studies with algae are available for alkyl polyglycosides. The influence of the chain length on the toxicity to algae is comparable to that on fish and invertebrate toxicity. Also in this case a clear correlation can be shown between the toxicity of alkyl polyglycosides and the carbon chain length; the available experimental database includes studies on alkyl polyglycosides ranging from D-Glucopyranose, oligomeric, butyl glycoside to D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess). Short-term toxicity to algae increases with increasing length of the hydrocarbon chain up to C16 and then decreases.

The 72-h EC50 values for algae determined for alkyl polyglycosides range from 12.5 mg/L for D-Glucopyranose, oligomeric, C10-16-alkyl glycosidesto 780 mg/L for D-Glucopyranose, oligomers, hexyl glycosides(freshwater). The 72-h NOEC values for algae range from 2 mg/L for D-Glucopyranose, oligomeric, C10-16-alkyl glycosidesto 125 mg/L for D-Glucopyranose, oligomers, hexyl glycosides.

Toxicity to microorganisms

Activated sludge respiration inhibition tests and Pseudomonas putida tests are available for the alkyl polyglycosides of chain lengths from D-Glucopyranose, oligomeric, butyl glycoside to D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess). No effects were observed for all of the substances across the category, and results range from 6h EC50 > 560 mg/L to 16h EC0 5000 mg/L.

Sediment Toxicity

All alkyl polyglycosides are well soluble in water (except for D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess)), have a low potential for bioaccumulation and are readily biodegradable, therefore they will degrade in the STP process. In case of release to sediment, the substances are expected to rapidly degrade in the environment, therefore sediment is not expected to be a compartment of concern for the majority of the category members.

Nevertheless, some studies are available for most of the category members (D-Glucopyranose, oligomers, hexyl glycosides; D-Glucopyranose, oligomers, decyl octyl glycosides;D-Glucopyranose, oligomers, branched and linear C9-11-alkyl glycosides; Reaction products of D-Glucose, n-Butanol and alcohols C10-12 (even numbered); D-Glucopyranose, oligomeric, C10-16-alkyl glycosides. Results from these studies range from an LC50 of 650.45 mg/kg dw to > 7023.1 mg/kg dw and NOEC values from 71.36 mg/kg dw to 698 mg/kg dw. Again, a trend of increasing toxicity with increasing carbon chain length could be observed.

Long-term data do not have to be generated because of the low to moderate log Koc values and the ready biodegradability of the test substances.

Terrestrial toxicity

Toxicity to terrestrial organisms is expected to be low. All alkyl polyglycosides exhibit an adsorption coefficient (log Koc) below 4 (except for D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess)) and are readily biodegradable. Hence, an indirect exposure via deposition of activated sludge to soil can be ruled out and persistency in soil is not expected. Moreover, the substances are acutely not very toxic in the aquatic compartment (EC/LC50 for fish, aquatic invertebrates and algae above 1 mg/L; according to ECHA Guidance on information requirements and chemical safety assessment, Chapter R.7c: Endpoint specific guidance). In case of exposure to soil, the substances are expected to rapidly degrade, thus the hazard to terrestrial organisms is negligible.

Nevertheless, studies on earthworms and terrestrial plants are available for some alkyl polyglycosides (D-Glucopyranose, oligomeric, butyl glycoside;D-Glucopyranose, oligomeric, C10-16-alkyl glycosides) and showed no toxic effects of these substances. No effects were observed up to 1000 mg/kg dw (D-Glucopyranose, oligomeric, butyl glycoside, 56d) and up to 654 mg/kg (D-Glucopyranose, oligomeric, C10-16-alkyl glycosides, 14d) in tests withEisenia sp.(OECD 222 and 207, respectively), and up to 654 mg/kg (D-Glucopyranose, oligomeric, C10-16-alkyl glycosides, 14d) in tests with terrestrial plants (OECD 208).

Table. Environmental Toxicity (*)

ID No.

Substance

CAS No.

Short term toxicity to fish 96h LC50

Long term toxicity to fish

Short term toxicity to aquatic invertebrates 48h EC50

Long term toxicity to aquatic invertebrates

Toxicity to aquatic algae

Toxicity to microorganisms

Terrestrial Toxicity

# 1

D-Glucopyranose, oligomeric, butyl glycoside

-

ER:> 51 mg/L,no effects in limit test

Data waiving

ER:> 51 mg/L,no effects in limit test

Data waiving

ER:72h ErC50 > 51 mg/L, NOECr >= 51 mg/L, no effects in limit test

Data waiving

ER:56d NOEC earthworms >= 1000 mg/kg dw

# 2

D-Glucopyranose, oligomers, hexyl glycosides

-

ER: 420 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER: 490 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER: 72h ErC50 780 mg/L, NOECr 125 mg/L

ER: 4h EC50 >1000 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

# 3

D-Glucopyranose, oligomers, decyl octyl glycosides

68515-73-1

ER: 100 mg/L, marine 96.6 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER: > 100 mg/L, marine 31.6 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER: 72h ErC50 27.2 mg/L, marine: ErL50 7 mg/L,NOECr 6 mg/L

6h EC50 > 560 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

# 4

D-Glucopyranose, oligomers, branched and linear C9-11-alkyl glycosides

157707-87-4

ER: marine LL50 >= 0.5 mg/L (limit test), RA from 110615-47-5:2.95 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER:26.2 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER:72h ErL50 9.05 mg/L, NOErLR 5 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

# 5

Reaction products of D-Glucose, n-Butanol and C10-12 (even numbered) alcohols

-

ER:129 mg/L, marine 78.4 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER: marine 19.95 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER: marine 72hErC50 8.4 mg/L, NOECr 3.5 mg/L

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

# 6

D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

-

ER: 2.95 mg/L, marine 4.4 mg/L

ER:NOEC 1.8 mg/L

ER: 7 mg/L, marine 4.33 mg/L

ER:EC10 1.76 mg/L

ER: 72h ErC50 12.5 mg/L, NOECr 2 mg/L, marine EL50 1.17 mg/L, NOEC 1.8 mg/L

ER: 16h EC0 5000 mg/L

14d EC50 earthworms, plants > 654 mg/kg dw

# 7

D-Glucose, reaction products with alcohols C16-18 (even numbered) (excess)

-

ER: >10,000 mg/L(no effects up to WS limit)

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER:3160 mg/L(no effects up to WS limit)

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

ER: 72h ErC5028 mg/L, ECr1021.7 mg/L(no effects up to WS limit)

ER: 30min EC10> 10,000 mg/L(no effects up to WS limit)

RA from D-Glucopyranose, oligomeric, C10-16-alkyl glycosides

# 8

Hexadecan-1-ol (a)

36653-82-4

ER: >0.4 mg/L (no effects up to WS limit)

--

--

--

ER: EL50 690 mg/L (no effects up to WS limit); EL10

--

--

#9

Octadecan-1-ol (a)

112-92-5

ER: >0.4 mg/L (no effects up to WS limit)

--

ER: 1700 mg/L (no effects up to WS limit)

ER: NOEC 0.98 mg/L (no effects up to WS limit)

ER: EL50 0.64 - 10 mg/L (no effects up to WS limit); EL10

--

--

 

(*) substances marked in bold are registered under REACH Regulation EC 1907/2006 in 2013, the remaining substances were registered in 2010.

(a) Surrogate substances: fatty alcohols. Available data on these substances are used for assessment of ecotoxicological properties by read-across on the basis of structural similarity and/or mechanistic reasoning.

Short-term aquatic toxicity tests with freshwater and/or marine species of three trophic levels (algae, aquatic invertebrates and fish) are available forReaction products of D-Glucose, n-Butanol and C10-12 (even numbered) alcohols. The short-term tests with fish exhibited LC50 values of 129 -278 mg a.i./L (range, for freshwater fish) and 78.4 mg a.i./L (marine fish), respectively. For marine aquatic invertebrates, an EC50 of 19.95 mg a.i./L was obtained. Algal toxicity testing with a marine species resulted in an EC50 of 8.4 mg a.i./L and a related NOEC of 3.5 mg a.i./L. No effects on the respiration rate and the growth of the microorganism Pseudomonas putida (EC0 (16 h) of 5000 mg a. i./L) were observed, and an EC0 (16 h) of 5000 mg/L was obtained.

There are no data available on long-term toxicity to fish and aquatic invertebrates.However, there are reliable data for category member substances which are considered suitable for read-across based on the category approach.Long-term toxicity tests with fish and Daphnia are available for the category member D-Glucopyranose, oligomeric, C10 -16 -alkyl glycoside. These studies resulted in a NOEC of 1.8 mg a.i./L for fish, and an EC10 value of 1.76 mg a.i./L for Daphnia, respectively.