Reaction products of 2,2-dimethylpropane-1,3-diol with 1-choloro-2,3-epoxypropane

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

OECD Guideline for Testing of Chemicals, Section 2, No. 201: "Freshwater Alga and Cyanobacteria, Growth Inhibition Test", adopted 23rd March, 2006, Annex 5 corrected: 28th July 2011.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Chemical name: Reaction products of 2,2-dimethylpropane-1,3-diol with 1-chloro-2,3-epoxypropane
CAS No.: 17557-23-2
EC / List no.: 701-333-0

Analytical monitoring:

yes

Details on sampling:

For the determination of the test item concentrations, three replicate samples (3 x 1 mL) were taken from the test concentrations at the start and at the end of the experiment. Three replicate samples (3 x 1 mL) were taken at the start of the test and six replicates were taken at the end of the test from the control. Analysis was performed by the analytical laboratory of TOXI-COOP ZRT. according to the analytical method validation (Study number:
555-100-6263) using LC-MS/MS method.
Details on the chemical analysis carried out (method, determination, results) are attached to the Report as Appendix III.

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

Raphidocelis subcapitata

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

Temperature: Culture temperature was checked at the beginning of the test and every 24 hours thereafter in a flask filled with water, in the climatic chamber. In addition, ambient temperature was continuously measured (with a min/max thermometer) within the climate chamber. The temperature was between 22.9 and 23.2°C measured in the flask and in the range of 22.7 – 23.6°C measured within the climate chamber.

pH:

The pH was measured in each test group at the start (before test solutions had been added into the test vessels) and in each test vessel at the end of the test. The pH of the control medium did not increase by more than 1.5 units during the test. The range of the
pH was 7.59 – 8.34 during the experiment. The pH of the test solutions was not adjusted during the experiment.

Details on test conditions:

The data of test conditions are detailed in Appendix I (Tables 9 and 10).

Exponentially-growing cultures of Raphidocelis subcapitata were exposed to the test item under defined conditions. The algal growth in relation to a control culture was determined over a fixed test period of 72 hours and, thus, over several algal generations. The test design included three replicates at the test concentrations and six replicates for the untreated control. The algae cell concentration was approximately 104 cells/mL at the start of the test in all of the test cultures. Glass Erlenmeyer flasks with total capacity of 250 mL were used as test vessels. The volume of the test liquid in the vessels was 100 mL. The algae cell concentration was determined by manual cell counting using microscope in each testing flask during the 72-hour test, in 24-hour intervals.

Reference substance (positive control):

yes

Remarks:

Name and data of Reference Item Name: Potassium dichromate (K2Cr2O7) Batch No.: K50498364 Description: Orange crystalline Expiry Date: 31 July 2023 Storage: Room temperature Supplier: MERCK KGaA

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 5.84 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 7.488 mg/L

95% CI:

>= 7.072 - <= 8.039

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

ca. 5.372 mg/L

95% CI:

>= 4.998 - <= 5.691

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 4.515 mg/L

95% CI:

>= 4.066 - <= 4.871

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

In this 72-h algal growth inhibition test with Raphidocelis subcapitata, the obtained results showed that the test item Reaction products of 2,2-dimethylpropane-1,3-diol with 1-chloro-2,3-epoxypropane had inhibitory effects on the growth of Raphidocelis subcapitata.

All validity criteria were met and therefore the study is considered as fully valid.

Biological results and endpoints are based on the measured and calculated test item concentrations.

Biological endpoints of the study are summarised below:

EC50: 7.488 m/l (growth rate)
NOEC: 5.84 mg/l (growth rate)

Executive summary:

Test item:	Reaction products of 2,2-dimethylpropane-1,3-diol with 1-chloro-2,3-epoxypropane
Test species:	Raphidocelis subcapitata (also known as Pseudokirchneriella subcapitata); Strain number: 61.81 SAG Exponentially-growing cultures; preculture was incubated for three days before the test.
Dilution water:	OECD medium, prepared in the laboratory of TOXI-COOP ZRT.
Concentrations:	Nominal concentrations of 1.28, 3.2, 8, 20 and 50 mg test item / L were investigated in the main study; a concurrent control was investigated in parallel. Mean of the measured test item concentrations did not remain within ± 20 % of the nominal by the end of the experiment in all of the test concentrations, therefore the biological results are based on the geometric mean of the measured concentrations. The corresponding calculated test item concentrations were 0.960, 2.29, 5.84, 14.2 and 35.8 mg test item/L.
Test design:	Exponentially-growing cultures of Raphidocelis subcapitata were exposed to the test item under defined conditions. The algal growth in relation to a control culture was determined over a fixed test period of 72 hours and, thus, over several algal generations. The test design included three replicates at the test concentrations and six replicates for the untreated control. The algae cell concentration was approximately 10^4 cells/mL at the start of the test in all of the test cultures. Glass Erlenmeyer flasks with total capacity of 250 mL were used as test vessels. The volume of the test liquid in the vessels was 100 mL. The algae cell concentration was determined by manual cell counting using microscope in each testing flask during the 72-hour test, in 24-hour intervals.
Analytics:	For determination of the test item concentrations, samples were taken from the applied concentration levels and control at the start and at the end of the test. Concentrations were determined using LC-MS/MS method.
Endpoints:	72-hour EC10, EC20, EC50, NOEC and LOEC for both response variables (i.e. average specific growth rate and yield).
Statistics:	For the determination of the LOEC and NOEC, Step-down Jonckheere-Terpstra Test (a = 0.05) was used (statistical software program ToxRatPro Version 3.3.0). The EC10, EC20, EC50 values were calculated by Probit analysis (statistical software program ToxRatPro Version 3.3.0).
Validity:	All validity criteria were met and therefore the study is considered as fully valid (see section 10.1)
Results:	All biological results are based on the geometric mean of the measured test item concentrations. The biological endpoints are summarised below in Table 1.

 

 

Table 1: Summary of the Biological Endpoints

Endpoints (0-72 h)	Growth rate (mg/L)	Yield (mg/L)
	Calculation based on measured concentrations
EC10	4.515	3.272
95 % conf. limits	4.066 – 4.871	2.554 – 3.741
EC20	5.372	3.772
95 % conf. limits	4.998 – 5.691	3.128 – 4.174
EC50	7.488	4.951
95 % conf. limits	7.072 – 8.039	4.604 – 5.156
NOEC	5.84	5.84
LOEC	14.2	14.2

 

 

Description of key information

green algae

Key value for chemical safety assessment

EC50 for freshwater algae:

7.488 mg/L

EC10 or NOEC for freshwater algae:

5.84 mg/L