2-amino-2-ethylpropanediol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 Aug 2010 - 11 May 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)

GLP compliance:

yes (incl. QA statement)

Remarks:

Swiss Federal Office of Public Health, Consumer protection directorate, Notification authority for chemicals, Bern, Switzerland

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0, 3.2, 10, 32, 100, 320, and 1000 mg/L
- Sampling method: For both definitive tests, samples were removed at test initiation and experimental completion from each test solution and the control. Samples analyzed on Day 0 were removed from the test solutions in the volumetric flasks prior to filling the individual test flasks. Samples analyzed at 96 hours of exposure were removed from the composite of the replicate vessels for each treatment and the control and were centrifuged for 5 minutes at 14000 rpm prior to analysis. Additionally, a sample from the abiotic control, which did not contain algae was removed. Three quality control (QC) samples fortified with AEPD and a blank control were prepared at each sampling interval at nominal concentrations approximating the test concentrations and remained with the exposure solution sample throughout the analytical process. Analysis of the QC samples was used to judge the precision and quality control maintained during the
analytical process.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: For both definitive tests a primary stock solution with a concentration of 1000 mg test item/L was prepared prior to test initiation by dissolving 1.0101 g (no pH adjustment) and 1.0090 g (pH adjustment) of the test item with 1000 mL dilution water. Different stock concentrations and volumes of dilution water (deionized water) were then used to achieve desired nominal test concentrations
- Eluate: no
- Controls: negative control, containing only dilution water
- Evidence of undissolved material: All resulting test solutions were shaken by hand prior to division into the replicate vessels and observed to be clear and colorless, with no visible undissolved test item.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: green alga
- Source (laboratory, culture collection): originally obtained from Albrecht-v.-Haller-Institut, Göttingen, Germany, and maintained in stock culture at Springborn Smithers Laboratories (Europe) (new Smithers Viscient AG).
- Age of inoculum (at test initiation): 3 days

ACCLIMATION
- Acclimation period: Three days prior to the definitive tests, the stock cultures were maintained within the following conditions: (1) Definitive Test 1 (no pH adjustment performed): continuous illumination at 7706 - 8014 lux, temperature 24 °C, shaking rate 128 rpm; (2) Definitive Test 2 (pH adjustment performed): continuous illumination at 4352 lux, temperature 24-25 °C, shaking rate 100 rpm
- Culturing media and conditions (same as test or not): yes

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

Definitive Test 1 (no pH adjustment performed): 22 to 25 °C
Definitive Test 2 (pH adjustment performed): 25 °C

pH:

Definitive Test 1 (no pH adjustment performed): 7.92 to 9.94
Definitive Test 2 (pH adjustment performed): 8.01 to 10.29

Nominal and measured concentrations:

nominal: 0, 3.2, 10, 32, 100, 320, and 1000 mg/L
measured: NA, 3.15, 9.60, 26.8, 95.2, 291, and 989 mg/L (Definitive Test 1, no pH adjustment performed)
measured: NA, 2.77, 8.85, 31.3, 108, 342 and 1005 mg/L (Definitive Test 2, pH adjustment performed)

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type: closed
- Material, size, headspace, fill volume: 250 mL flasks filled with 100 mL test solution
- Aeration: stainless steel caps permitted gas exchange
- Initial cells density: 151 x 10^4 cells/mL (Definitive Test 1, no pH adjustment performed), 139 x 10^4 cells/mL (Definitive Test 2, pH adjustment performed)
- Control end cells density: 53.3 x 10^4 cells/mL (Definitive Test 1, no pH adjustment performed), 100 x 10^4 cells/mL (Definitive Test 2, pH adjustment performed)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water
- Culture medium different from test medium: no
- Intervals of water quality measurement: temperature continuously in adjacent flask, pH after 72 and 96 h

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: yes (Definitive Test 2)
- Photoperiod: continuous
- Light intensity and quality: 3943 to 4664 lux (Definitive Test 1: no pH adjustment performed), 3910 to 4690 lux (Definitive Test 2: pH adjustment performed), Lighting was supplied by fluorescent bulbs

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: cell count in counting chamber (hemocytometer (Neubauer Improved) and a Leica DMLS microscope) and observation of the health of the algal cells each 24 h

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

158 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: Definitive Test 1 (no pH adjustment performed); 95% CL: 145-169

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

26.8 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: Definitive Test 1 (no pH adjustment performed)

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

225 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Definitive Test 1 (no pH adjustment performed); 95% CL: 216-232

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

26.8 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Definitive Test 1 (no pH adjustment performed)

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

65.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: Definitive Test 2 (pH adjustment performed); 95% CL: 29.5-118

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

31.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: Definitive Test 2 (pH adjustment performed)

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

548 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Definitive Test 2 (pH adjustment performed); 95% CL: 426-620

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

31.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Definitive Test 2 (pH adjustment performed)

Reported statistics and error estimates:

The data of both tests were first checked for normality using Shapiro-Wilks' Test and for homogeneity of variance using Bartlett's Test. The data for
yield and growth rate of the second definitive test passed the test for normality. Due to zero variance in one of the test groups of the first definitive test, the homogeneity test could not be performed and further transformation of the data was useless. ANOVA and Bonferroni t-Test were considered to be the most conservative test to determine the NOEC and LOEC values. All statistical determinations were made at the 95% level of certainty, except in the case of Shapiro-Wilks' and Bartlett's Tests, where the 99% level of certainty was applied. TOXSTAT® version 3.5 was used to perform these calculations.

Based on the behaviour of the test item in algal medium and the impact on the pH of the solution (increase), a second exposure was performed using pH adjustments (pH 8.0 ± 0.1) of the exposure solutions. The second exposure (Definitive test 2) should be considered more robust than those of the first exposure (Definitive test 1). The exposure conditions provided during the second test are more conclusive to optimal algal growth and it is clear that the pH shift impacted the observed endpoints in the first exposure.

Description of key information

ErC50(72h) = 548 mg/L for Pseudokirchneriella subcapitata (OECD 201)
NOEC(72h) = 31.3 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

548 mg/L

EC10 or NOEC for freshwater algae:

31.3 mg/L

Additional information

There is one study on algal toxicity available for 2-amino-2-ethyl-1,3-propanediol (AEPD), which was used as key study for the assessment. The study was conducted according to OECD guideline 201 and GLP (Hoffmann, 2011). The test organism Pseudokirchneriella subcapitata was exposed to AEPD in a static system for 72 hours, at the test concentrations 11, 24, 55, 150, 390 and 980 mg a.i./L. The test was performed with and without pH adjustment, leading to growth rate based EC50 values of 548 mg/L and 225 mg/L, respectively. NOEC values were 31.3 mg/L and 26.8 mg/L, with and without pH adjustment, respectively. Based on this data, pH had an effect on algal growth, and the value obtained with pH adjustment should be used for the assessment of toxicity.