N,N-dimethyldecylamine N-oxide

Endpoint summary

Description of key information

Fish:

Acute: 96 -h LC50 = 31.8 mg AO/L (Danio rerio) based on read-across to C12 AO.

Chronic: NOEC = 0.42 mg/L (Pimephales promelas) based on read across to full life-cycle toxicity test for C12 -14 AO.

Invertebrates:

Acute: 48 -h EC50 = 3.43 mg AO/L (Daphnia magna) based on geometric mean of data available for C12 AO, C14 AO and C12 -14 AO.

Chronic: 21 -day NOEC = 0.70 mg AO/L (Daphnia magna) based on read-across to C12 -14 AO.

Algae:

72-h ErC50 = 0.16 mg AO/L (Pseudokirchneriella subcapitata) based on geometric mean of data available for C1 A), C12 AO, C14 AO and C12 -14 AO.

28 -d NOEC ≥ 67 µg AO/L (periphyton study) based on read-across to C12 -14 AO.

Additional information

Fish: No acute fish toxicity studies have been performed using C10 AO. However, data are available C12 AO, C14 AO and C12-14 AO.

The acute toxicity of C12 AO to Zebra fish (Danio rerio) was determined in a 96-hour semi-static test performed according to OECD TG 203. The 96-h LC50 was reported as 31.8 mg AO/L [Mark UE & Arends ICM (1992)].

Two reliable studies are available for C14 AO. In the first study, performed according to OECD TG 203, Danio rerio were exposed to the substance under semi-static conditions for 96 hours [Mark UE & Arends ICM (1992)]. The 96-h LC50 was 2.4 mg AO/L. In the second study, also performed according to OECD TG 203, Danio rerio were exposed to the substance for 96 hours [Jung R (1987)]. The 96-h LC50 was between 2.5 and 25 mg AO/L.

There are four reliable studies available for the C12-14 AO. Iwan GR et al (1975) exposed Fathead minnow (Pimephales promelas) to C12-14 AO under static conditions for 96 hours. The LC50 (96 h) based on nominal concentrations of amine oxide ranged from 2.67 to 3.46 mg AO/L depending on the source and pH of the water used. In a supporting study Bluegill (Lepomis macrochirus) were exposed to C12-14 AO under static conditions for 96 hours. The LC50 value was reported as 3.13 mg AO/L [Macek & Sleight (1972)]. Exposure of rainbow trout (Oncorhynchus mykiss) to C12-14 AO under static conditions for 96 hours resulted in a LC50 of 12.6 mg AO/L [Dommrose AM (1987)], whilst exposure of Danio rerio to C12-14 AO under static conditions resulted in a 96 -h LC50 of 3 -30 mg AO/L [Hoechst AG (1987)].

Most of the available studies on fish toxicity have been performed using Danio rerio. Unfortunately, some of the studies only report the toxicity in terms of a range rather than a more precise value. However, the results on this species are consistent with results on Oryzias latipes, Lepomis macrochirus and Pimephales promelas. Onchorhynchus mykiss shows the lowest sensitivity to C12-C14 and is assumed to be more resistant to AO than other species of fish.

Based on the available studies toxicity to fish increases moving from the C12 AO monoconstituent to C14 AO monoconstituent or the C12-14 AO UVCB. It is anticipated that the toxicity of C10 AO to fish will be of the same order of magnitude as C12 AO or even lower. In this case it is acceptable to read across from the toxicity value of C12 AO, i.e. LC50 = 31.8 mg AO/L as this is likely to represent a worst case assessment for C10 AO.

No chronic fish toxicity studies have been performed using C10 AO. However, data are available for C12-14 AO. In the acute studies it was found that toxicity to fish increased as the chain length increased from C12 AO to C14 AO. It is expected that a similar trend would be seen in the chronic studies and on this basis the study with C12-14 AO would represent a worst case for C10 AO.

In a full life-cycle toxicity test (similar to EPA OPPTS 850.1500) fathead minnows (Pimephales promelas) were exposed to the substance for 302 days under flow through conditions [Aquatic Environmental Services (1976)]. The nominal test concentrations were 0, 0.06, 0.13, 0.25, 0.50, and 1.0 mg AO/L . Mean measured concentrations were 82 -117% of nominal. Endpoints included survival, growth, and hatchability. The NOEC was 0.42 mg AO/L (mean measured concentration), based on reduced fry survival, reduced egg hatch, and occluded eyes in test fish. This was consistent with results of a preliminary 15 -day test, in which the NOEC was 0.495 mg AO/L.

Daphnia: No acute daphnia studies have been performed using C10 AO. However, data are available C12 AO, C14 AO and C12-14 AO.

Two reliable studies are available for C12 AO. In both studies, performed according to OECD TG 202, Daphnia magna were exposed to C12 AO under static conditions for 48 hours. The 48-h EC50 based on nominal concentrations were 3.9 mg AO/L [Shacklady LG (2001)] and 4.24 mg AO/L [Mark UE & Garttener-Arends ICM (1994)]. One reliable study is available for C14 AO. In this study, performed according to OECD TG 202, Daphnia magna were exposed to C14 AO under static conditions for 48 hours. The 48-h EC50 based on nominal concentrations was 2.63 mg AO/L [Mark UE & Garttener-Arends ICM (1994)]. Three reliable studies performed using Daphnia magna are available for C12-14 AO. All three studies were performed to OECD TG 202 under static conditions. The EC50 (48h) values (nominal) obtained were 3.1 mg AO/L [Noack M (2001)], 2.9 mg AO/L [Mark U & Meuwsen IJB (1990)] and 4.2 mg AO/L [Beneventi S (2005)]. 

Based on the available studies, it can be seen that there is a slight trend shown for toxicity to daphnia to increase as the alkyl chain length increases going from monoconstituent C12 AO to C14 AO with C12-14 AO having intermediate toxicity compared to C12 AO and C14 AO. On this basis, taking a geometric mean of the available data for C12 AO, C14 AO and C12-14 AO gives a worse case estimate of the likely toxicity of C10 AO. The estimated 48-h EC50 = 3.43 mg AO/L.

No chronic daphnia toxicity studies have been performed using C10 amine oxide. Data are read across from C12-14 AO as this is expected to represent a worse case for the shorter alkyl chain length as demonstrated from the acute daphnia results for C12 AO, C14 AO and C12-14 AO.

A 21-day survival and reproduction test with Daphnia magna following OECD TG 211 is available for C12-14 AO [Maki (1997)]. The 21 -day NOEC was 0.70 mg AO/L, based on both survival and reproduction.

 

Algae: One acute algal toxicity study is available for C10 AO however the reliability of this study could not be fully assessed. In this study performed according to OECD 201 Pseudokirchneriella subcapitata were exposed to C10 AO at nominal test concentrations of 0, 0.04, 0.1, 0.2, 0.3 or 1 mg AO/L for 72 hours [De Messemaeker (2007)]. The 72-h ErC50 was 0.19 mg AO/L. No NOEC value was derived.

Data are also available for C12 AO, C14 AO and C12-14 AO.

In a 72-hour algal growth inhibition study performed according to OECD 201 Pseudokirchneriella subcapitata were exposed to C12 AO at nominal test concentrations of 0, 0.014, 0.028, 0.057, 0.114 or 0.228 mg AO/L [Mark UE & Arends ICM (1992)]. The 72-h ErC50 was 0.20 mg AO/L. No NOEC value was derived.

One reliable study is available for C14 AO. In this study, performed according to OECD 201, Pseudokirchneriella subcapitata were exposed to C14 AO for 72 hours at nominal test concentrations of 0, 0.024, 0.047, 0.095, 0.190 or 0.379 mg AO/L [Mark UE (1992)]. The 72-h ErC50 was 0.19 mg AO/L. No NOEC value was derived.

Six reliable studies are available for C12-14 AO. In a study performed according to OECD TG 201 under GLP [Ginkel & Kroon (1990)] Pseudokirchneriella subcapitata were exposed to C12-14 AO under static conditions for 72 hours at nominal concentrations of 0, 0.020, 0.039, 0.078, 0.155 or 0.31 mg AO/L. The ErC50 (72 h) was 0.266 mg AO/L. In three supporting studies performed according to OECD TG 201 Pseudokirchneriella subcapitata were exposed to C12-14 AO for 72 hours under static conditions. ErC50 values of 0.159 mg AO/L [Brill J (2010)], 0.12 mg AO/L [Hanstveit & Oldersma (1997)] and 0.082 mg AO/L [Hanstveit & Oldersma (1997)] were reported. Exposure of Chlorella vulgaris to C12-14 AO for 72 hours under static conditions in accordance with OECD TG 201 resulted in an ErC50 of 1.14 mg AO/L [Vreys (2003)], whilst exposure of Desmodesmus subspicatus to C12-14 AO for 72 hours under static conditions in accordance with OECD TG 201 resulted in an ErC50 of 0.25 mg AO/L [Scheerbaum (2000)].

From the available studies for C12-14 AO it appears that Pseudokirchneriella subcapitata is the most sensitive of the species tested. It is noted that the ErC50 values from studies performed using this species are consistent over the range of C10 AO (0.19 mg AO/L), C12 AO (0.20 mg AO/L), C12-14 AO (0.082, 0.12, 0.159 &0.266 mg/L) and C14 AO (0.19 mg AO/L). Therefore it was decided to use a weight of evidence approach and to derive the ErC50 value for C10 AO using the geometric mean of the data available for Pseudokirchnerella subcapitata. This results in a 72-h ErC50 value of 0.16 mg AO/L.

The toxicity of C12-14 AO to algae was evaluated in a 28 -day freshwater periphyton microcosm assay [Belanger (1999)]. The No-Observed Effect Concentration (NOEC) of the substance to the periphyton community was determined to be ≥ 67 µg AO/L, the highest test concentration evaluated (mean measured concentration). The results of the acute toxicity tests on Pseudokirchnerella subcapitata performed with C10 AO, C12 AO, C12-14 AO and C14 AO showed that there was no effect on acute toxicity to algae due to differences in alkyl chain length over the range of chain lengths considered. It is expected that this finding is also applicable to the periphyton study and hence the result of this study may be read across to C10 AO.

Microorganisms: In accordance with REACH Annex VIII section 9.1.4, Column 2 activated sludge respiration inhibition testing does not need to be conducted if the substance is found to be readily biodegradable and the applied test concentrations are in the range of concentrations that can be expected in the influent of a sewage treatment plant. Two studies are available (IUCLID section 5.2.1) which show that C10 AO is readily biodegradable. In the key study [Noack M (1997)] a test concentration of 45.9 mg AO/L was used. This value is higher than the influent concentration of a sewage treatment plant predicted by modelling. On this basis the study may be waived.