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Toxicity to aquatic algae and cyanobacteria

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Description of key information

With high probability 2,2',2"-nitrilotriethanole is acutely not harmful to algae.

Key value for chemical safety assessment

EC50 for freshwater algae:
512 mg/L
EC10 or NOEC for freshwater algae:
26 mg/L

Additional information

The assessment of the algal toxicity is based on effect data taken from the “Commission for the Evaluation of Substances Hazardous to Waters” (KBwS) data sheet no. 201, which is part of the German Federal Water Act (Article 19g). Based on the collected data a substance is classified according to its water-hazardous properties (WGK 1 to 3). Triethanolamine was classified as WGK 1, which indicates a low hazard to waters. As the list with the classified substances was published in the Bundesanzeiger (Ref. 4), the classification is legally binding for the industry.

 

The data sheet lists three sources for effect data on algae (see table below) of which only one was performed according to a national standard method (Amann & Steinhäuser, Ref. 1) while the other two are of questionable reliability due to exposure period or documentation (Bringmann & Kühn, Ref. 2; Verschueren, Ref. 8).

 

Species

Not neutralised

Neutralised

Remark

Ref.

EC10

(mg/L)

EC50 (mg/L)

EC10 (mg/L)

EC50 (mg/L)

Desmodesmus subspicatus

7.9

216

26

512

Reliability 2; key data:

DIN 38412, part 9; exposure duration: 72 h; based on growth rate; pH values not specified

1

Scenedesmus quadricauda

EC3: 1.8

-

EC3: 715

-

Reliability 2; disregarded data: exposure period (8 days) is significantly longer than the standard period of 72 h; in addition, there is confusion between results for neutralised and non-neutralised test results; here displayed correctly; no guideline followed; pH values not specified

2

Scenedesmus

NOEC: 100

-

-

-

Reliability 4; disregarded data:

no detailed information reported (e.g. on exposure duration, test concentrations, effect parameter, etc); pH values not specified

8

Additional information

Phaeodactylum tricornutum

EC10: > 10;

NOEC:

< 28

204

-

-

Reliability 2, supporting data:

Seawater species, ISO 10253; exposure: 72 h with light/dark cycle 16/8 h; pH values not specified

7

Skeletonema costatum

-

>107 -<260

-

-

Reliability 2, supporting data:

Seawater species, ISO 10253; exposure duration: 72-h, constant light; pH values not specified

9, 10

Desmodesmus subspicatus

-

-

110

750

Reliability 2; disregarded data:

test period not in accordance with the requirements of REACH (48 h instead of 72 h); DIN 38412, part 9; exposure duration: 48 h; stock solutions adjusted to 8.0 ±0.3; pH range in the control during the test: 8.1 to 9.6

6

Colpoda

NOEC: 160

-

-

-

Reliability 4; disregarded data:

no detailed information reported (e.g. on exposure duration, test concentrations, effect parameter, etc); pH values not specified

8

Chlorococcales (mixed population)

NOEC:

> 1000

-

-

-

Reliability 2, disregarded data:

test period not in accordance with the requirements of REACH (24 h instead of 72 h); pH values not specified

11

 

The data from Amann & Steinhäuser (Ref. 1) were generated within the research project “Assessment of Water-Hazardous Substances” which served the scientific support and administration of a “Commission” in their work of the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.

 

The algal toxicity tests were performed according to DIN 38412, part 9 (draft). Tests were performed in neutral medium unless noted otherwise. In case of triethanolamine, the test was performed with neutralised and not neutralised test medium in parallel. The test species was Scenedesmus subspicatus (new name:Desmodesmus subspicatus). The EC10 was determined being the relevant factor for the WGK classification. The effect data were evaluated based on growth rate in accordance with the information requirements of REACH.

 

For the risk assessment the effect data for the neutralised test medium should be used. The effect values show a higher toxicity using non-neutralised test medium with regard to the EC50; therefore, part of the observed toxicity is due to the change in pH induced by the substance at higher test item concentrations. For the risk assessment the effect data for the neutralised test medium should be used since the quantities of TEA that would be found in natural waters are not likely to affect the pH to a relevant extent. It is likely that the EC50 value from the test without neutralisation overestimates the potential toxicity of these matrices. However, TEA is considered to be not harmful to aquatic algae in any case since, irrespective of the pH, all determined EC50 values were > 100 mg/L and all determined EC10 values were > 1 mg/L.

 

The acute toxicity test was performed without analytical verification of the test concentrations. However, the stability of TEA in the test medium is considered to be stable due to the high water solubility (WS = >1000 g/L at 20 °C), the low vapour pressure (VP = < 3E-04 hPa at 21 °C), the low adsorption potential (log Koc (uncharged; MCI-method): 1; log Koc (charged): 1.23 at pH 7) and the low Henry´s law constant (HLC (uncharged): 4.2E-7 Pa*m³/mol) of the chemical. 

 

Detailed data on the study itself, e.g. biomass growth rate as well as growth curves are not available; in addition, detailed pH-values were not reported. Nevertheless, the test results were performed according to national standards and peer-reviewed by the KBwS during the performance of the research project. Therefore, the data can be regarded as reliable with restrictions (RL 2) and should be used as key study for the risk assessment.

 

The result by Amann & Steinhäuser (1) is supported by the published effect values for a seawater algaePhaeodactylum tricornutumby Libralato et al. (2010) and the information on the seawater algae Skeletonema costatum published by Eide-Haugmo et al. (2009/2012). Other data which are available for triethanolamine do not contradict the selected key values, but should not be used for risk assessment purposes due to insufficient exposure duration and documentation.

 

The study performed by Amann & Steinhäuser was identified as key study. A 72-h ErC50 of 216 mg/l for non-neutralized samples and a 72-h ErC50 of 512 mg/l for a neutralized sample were determined onDesmodesmus subspicatusaccording to German Industrial Standard DIN 38412, part 9 (draft). The corresponding ErC10 values are 7.9 (non-neutr.) and 26 mg/L (neutr.). This result is supported by published data on a seawater algae (Phaeodactylum tricornutum; Libralato et al., 2010), which gave similar effect values in non-neutralised test solutions: EC50 = 204 mg/L; EC10 > 10 mg/L; NOEC < 28 mg/L. In addition, the seawater algae Skeletonema costatum (Eide-Haugmo et al., 2009/2012) also supports this level of sensitivity, although the EC50 could only be determined as a range of > 107 and < 260 mg/L.

 

Based on the presented data, it can be concluded that triethanolamine is acutely not harmful to algae.

 

References

1)   Amann W. & Steinhäuser KG (1986, 1988). 1. und 2. zusammenfassender Zwischenbericht zum F+E Vorhaben „Bewertung wassergefährdender Stoffe“ Teil I (FV-Nr. 82-102 05 308); Bayerisches Landesamt für Wasserwirtschaft, München [Interim Report, Evaluation of substances hazardous to water].

2)   Bringmann G. & Kühn R. (1977). Z Wasser Abwasser Forsch 10, 87-98.

3)   DIN 38412, part 9 (draft).German standard methods for the examination of water, waste water and sludge; bio-assays (group L); determination of the inhibitory effect of water constituents on the growth ofScenedesmusgreen algae (L 9).

4)   Federal Ministry of Justice (2005). Bundesanzeiger No. 142 a.

5)   ISO, Standard 10253 (2006). Water Quality—Marine Algal Growth Inhibition Test withSkeletonema costatumandPhaeodactylum tricornutum.

6)   Kühn R and Pattard M (1990). Results of the harmful effects of water pollutants to green algae (Scenedesmus subspicatus) in the cell multiplication inhibition test. Water Research 24(1), 31-38.

7)   Libralato G., Volphi Ghirardini A., Avezzù F. (2010). Seawater ecotoxicity of monoethanolamine, diethanolamine and triethanolamine. J Hazardous Materials 176, 535-539.

8)   Verschueren K. (1983). Handbook of environmental data on organic chemicals, 2nd edition. Van Nostrand Reinhold Company, New York.

9)  Eide-Haugmo I, Brakstad OG, Hoff KA, Sorheim KR, Falck da Silva E, Svendsen HF (2009).Environmental impact of amines. Energy Procedia 1: 1297-1304.

10) Eide-Haugmo I, Brakstad OG, Hoff KA, Falck da Silva E, Svendsen HF (2012).Marine biodegradability and ecotoxicity of solvents for CO2-capture of natural gas.International Journal of Greenhouse Gas Control 9: 184-192.

11) Krebs F. (1991). Bestimmung der biologischen Schadwirkung wassergefaehrdender Stoffe im Assimilations-Zehrungs-Test (A-Z-Test).DGM 35(5/6): 161-170.