Benzenepropanal, 2-methyl-4-(2-methylpropyl)-

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:

26 May, 2015 to 05 October, 2015

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

23 March, 2006, with updated Annex V of 28 July, 2011.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

NYMPHEAL (GR-88-0778) :
Lot No. : Batch 6
Purity : 99.1% (sum of isomers)
Date of Expiry : 29 March, 2017

Analytical monitoring:

yes

Remarks:

GC-MS

Details on sampling:

Water samples were taken for extraction and analysis, as follows :
- Exposure samples (C1 - C5) - Time 0, 48 hours, 72 hours
- Control and Solvent Control - Time 0 and 72 hours
- Stability samples (without the presence of algae, and, without the presence of algae and light) at the intermediate test concentration C3 (nominal 1.03 mg/L) - analysed following 48 and 72 hours of incubation.

Vehicle:

yes

Remarks:

Stock solutions prepared in Acetone. Maximum loading in exposure media : 0.1 mL/L.

Details on test solutions:

Following a Range-Finding study, the Following Nominal test concentrations were chosen for the definitive study :
C1 0.21 mg/L
C2 0.47 mg/L
C3 1.03 mg/L
C4 2.27 mg/L
C5 5.00 mg/L
The exposure solutions were prepared using standards prepared in Acetone as a vehicle. Since NYMPHEAL is a primary aldehyde, and, therefore, susceptible to undergo rapid oxidation, it was decided to avoid long, drawn-out exposure medium preparation techniques (e.g. slow-stirring to obtain water saturated fraction).

A blank Control and Solvent Control were also performed.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Desmosdesmus subspicatus

Pre-Culture Conditions :
Pre-Culture Vessels : 300 mL Erlenmeyer flasks
Culture Medium : Modified OECD Medium (OECD 201, EN ISO 8692)
pH value of algal medium : 8.2
Volume of liquid for Stock Culture : 100 +/- 5 mL
Number of Replicates : 2
Light : Permanently illuminated
Light Intensity : 60 - 120 microE/m2/s
Shaker : 100 +/- 5 oscillations/minute
Temperature : 21 - 24 °C (+/- 2°C)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22 °C (21.5 - 22.9 °C)

pH:

pH of test medium : 8.3
pH in test solutions : 8.5 - 9.1

Nominal and measured concentrations:

The water samples were simultaneously analysed for the residue of the Parent, and the corre-sponding alcohol (GR-88-1108) and acid (GR-88-1910).

NYMPHEAL was not stable in the exposure solutions over the 24-hour renewal period. The concentrations determined in the Fresh medium samples at Time 0 varied in the range of 81 to 107 % of Nominal, and, between less than LOQ - 91% of Nominal in the 48 hour old samples, decreasing further by 72 hours.

The Time-Weighted Mean Measured concentrations of the Parent over the 96-hour exposure period were, as follows :

Exposure Level Time-Weighted Mean Concn.
Control Not Detected
Solvent Control Not Detected
C1 (0.21 mg/L) 0.052 mg/L
C2 (0.47 mg/L) 0.123 mg/L
C3 (1.03 mg/L) 0.475 mg/L
C4 (2.27 mg/L) 1.30 mg/L
C5 (5.00 mg/L) 3.62 mg/L

By 72 hours, detects of the Acid Metabolite represented more-or-less the totality of Nympheal équivalents detected.

An average of 83% of Nympheal was recovered after 72 hours of incubation of the stability control samples (i.e. C3 without algae, and C3 without algae and no light).

Details on test conditions:

Test Vessels : 60 mL glass vials, air-tightly closed bÿ a screw-cap with PTFE lining
Volume of Exposure Medium : 60 +/- 2 mL
Age of Pre-Culture : 4 days
Number of Cells per mL of Test Solution : 5000 cells/mL
Number of Replicates per test item concentration : 3
Number of Replicates in the Control : 3
Number of Replicates in the Solvent Control : 6
Light Regime : 24 hours of light
Light Intensity : 68.2 - 78.4 microS/cm2/s
Temperature : 21.5 - 22.9 °C
Shaker : 100 +/- 5 oscillations/minute
Test Duration : 72 hours
Counting of Algae : Daily

Reference substance (positive control):

yes

Remarks:

Potassium Dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.55 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% Confidence Interval Limits : 1.47 - 1.62 mg/L

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.561 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% Confidence Interval Limits : 0.502 - 0.617 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.123 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: NOEC for Growth Rate and Yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.719 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: 95% Confidence Interval Limits : 0.675 - 0.766 mg/L

Results with reference substance (positive control):

A reference test using Potassium Dichromate as reference item was performed in December 2014.

Result : ErC50 (0 - 72 h) = 0.940 mg/L (95% CI 0.900 - 0.983 mg/L)

This result is in accordance with the range provided in the international ring test (ISO, 2004).

Validity criteria fulfilled:

yes

Conclusions:

An algal growth inhibition test with Desmodesmus subspicatus was performed with NYMPHEAL. The corresponding end-points at 72 hours of incubation are :

72 hr ErC50 = 1.55 mg/L
72 hr ErC10 = 0.561 mg/L
72 hr NOErC = 0.123 mg/L
72 hr EyC50 = 0.719 mg/L
72 hr EyC10 = 0.305 mg/L
72 hr NOEyC = 0.123 mg/L

Executive summary:

An algal growth inhibition test with Desmodesmus subspicatus was performed with NYMPHEAL. The corresponding end-points at 72 hours of incubation are :

72 hr ErC50 = 1.55 mg/L

72 hr ErC10 = 0.561 mg/L

72 hr NOErC = 0.123 mg/L

72 hr EyC50 = 0.719 mg/L

72 hr EyC10 = 0.305 mg/L

72 hr NOEyC = 0.123 mg/L

Description of key information

OECD 201 - Algal Inhibition :

ErC50 (72 hr) = 1.55 mg/L

ErC10 (72 hr) = 0.561 mg/L

NOErC (72 hr) = 0.123 mg/L

EyC50 (72 hr) = 0.719 mg/L

EyC10 (72 hr) = 0.305 mg/L

NOEyC (72 hr) = 0.123 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.55 mg/L

EC10 or NOEC for freshwater algae:

0.561 mg/L

Additional information

OECD 201 - Algal Inhibition :

ErC50 (72 hr) = 1.55 mg/L

ErC10 (72 hr) = 0.561 mg/L

NOErC (72 hr) = 0.123 mg/L

EyC50 (72 hr) = 0.719 mg/L

EyC10 (72 hr) = 0.305 mg/L

NOEyC (72 hr) = 0.123 mg/L.