Propane-1,3-diol

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

ACC PDO panel assigned reliability of 1. PDO from chemical process.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

The concentration of NaHCO3 was increased to be twice of that indicated in the Guideline 201. This concentration has been found to be optimal.

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: All test concentrations including control were sampled.
- Sampling method: At the beginning and every 24 hours, two portions of 50 mL per sample.
- Sample storage conditions before analysis: The samples to be tested and pure test water (2000 mL OECD 201) were stored deep frozen and protected from light until analyses were preformed.

Vehicle:

no

Details on test solutions:

The test substance was introduced into deionized water by stirring with magnetic stirrer. A stock solution with 12.5 g test substance dissolved in deionized water was prepared and the following test concentrations were prepared: 0.5 g, 1.0 g, 2.0 g, 4.0 g, 8.0 g, and 10 g test substance per liter. For the test solution, 40 mL of each solution was completed with 5 mL intermediate dilution and 5 mL algal suspension up to 50 mL. For each concentration, three aliquots were incubated under constant light. The second part was diluted equivalent to the test solution, the algal suspension being replaced by a 1:10 diluted intermediate dilution blank. Only one aliquot of the respective blanks was incubated under the same conditions as described above. The incubation of the main culture took place under the same conditions as the preculture. The algae were held in suspension by stirring on a magnetic stirrer. By dilution with preculture medium, the cell concentration was adjusted to 10e5 cells/mL. The initial cell concentration in the test solution was 10e4 cells/mL.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: 86.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen [SAG].
- Method of cultivation: The alga were held in a stock culture according to a separate SOP. Three days prior to the test, a pre-culture was prepared. The algal stock culture was diluted to an initial cell concentration of 10000 cells/mL using a preculture medium.

ACCLIMATION
- Culturing media and conditions: The incubation of the main culture took place under the same conditions as the preculture.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Not reported

Test temperature:

25 ± 1°C

pH:

at 0 hours: 7.60-7.91
at 72 hours: 8.02-9.16

Dissolved oxygen:

Not reported

Nominal and measured concentrations:

Nominal (g/L): 0, 0.5, 1, 2, 4, 8, 10
Measured concentrations: 92.6-102% of nominal

Details on test conditions:

TEST SYSTEM
- Test vessel:
- fill volume: 50 mL
- Aeration: Stirring with magnetic stirrer to keep the cells suspended and in contact with CO2.
- Initial cells density: 10000
- Control end cells density: x16 times the original concentrations.
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes
The mineral nutrient medium was prepared from four stock solutions (according to the SOP Ö 031 1 of Institut Fresenius Taunusstein ):
Mineral Nutrient Salts Solution I
Fe-Complex Solution II
Trace-Elements Solution III
Sodium hydrogen carbonate Solution IV

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water

OTHER TEST CONDITIONS
- Light intensity and quality: 8000 lux (measured within the range of 400-700 nm)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Inhibition of biomass production at 24 hour intervals.
Inhibition of growth rate.
As a measure for the biomass of algae, photointensity at 578 nm was monitored.
- Determination of cell concentrations: photometrical

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

500 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

700 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1 600 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

4 000 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

other: ErC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

500 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes

Reported statistics and error estimates:

The inhibition of the biomass production and of the growth rate of the algae was calculated according to the guideline. The determined values were plotted on probit paper and the respective values for the effective concentrations were taken from the graph.

Nominal Concentration (g/L)	Number of cells			Inhibition of Biomass production (%)	Inhibition of Growth Rate (%)
	24 H	48 H	72 H
0	97905	420510	1262333	0	0
10	52430	54570	89880	93.3	19.0
8	58850	81320	223630	83.9	12.4
4	57780	161570	280340	73.8	10.8
2	53500	225770	405530	62.3	8.2
1	69550	256800	820690	38.6	3.1
0.5	83460	436560	1317170	-2.7	-0.3

Validity criteria fulfilled:

yes

Conclusions:

72 hour NOEC was 0.5 g/L based on biomass and growth rate. 72 hour EC50 based on biomass and growth rate were 1.6 and >10 g/L, respectively.

Executive summary:

The toxicity of 1,3-propanediol was investigated in a 72-hour test in algae according to OECD Guideline 201. Nominal test concentrations included 0, 0.5, 1, 2, 4, 8, and 10 g/L. The toxic effect was investigated by determination of the inhibition of biomass production and the growth rate of the algae. The NOEC was determined to be 0.5 g/L based on biomass and growth rate. The inhibition of biomass production to 10 and 50% (EbC10 and EbC50) was calculated to be 0.7 g/L and 1.6 g/L, respectively. The inhibition of the growth rate to 10 and 50% (ErC10 and ErC50) was calculated to be 4.0 and > 10 g/L, respectively.

Description of key information

72h ErC50 for freshwater algae: >10000 mg/L