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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

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

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
28 July 2011
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Reference substance name:
Reaction products of (Z)-octadec-9-enol and lactic acid
IUPAC Name:
Reaction products of (Z)-octadec-9-enol and lactic acid
Test material form:
liquid
Specific details on test material used for the study:
Test Substance
Test Substance Name: Dermol OL
CAS Number: 42175-36-0
Batch Number: P7610
Purity: 100 %
Receipt Date: 01 February 2018
Retest Date: January 2020
Storage on Receipt: Room temperature (15 – 30°C)

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
At approximately 24-hour intervals after the start of the incubation period,
pre-determined volumes of test media (1.0 mL at 24 hours and 0.5 mL at 48 and
72 hours) were removed from each incubated test vessel, and transferred to
individually identified cell counting vials. The contents of each vial were diluted to a
10 mL final volume with an electrolyte solution. The cell density of the vial contents
was then determined using a particle counter (Z2 Coulter Counter®).

Test solutions

Vehicle:
no
Details on test solutions:
Based on the results of the range-finding test the definitive test was conducted with a
control and nominal test concentrations of 1.0, 3.2, 10, 32 and 100 mg/L LR WAF.
The results from the initial definitive test have not been reported.
Six test vessels were prepared for the control (EC medium only) and three replicate
test vessels were prepared for each test concentration, each with an initial cell
concentration of 1 × 104 cells/mL. A blank vessel (not inoculated with algae) was
prepared during the definitive test at control only to establish back ground counts on
the coulter, these counts were later subtracted from the cell counts.
At the start of the test, amounts of test substance (1.03, 3.19, 10.06, 32.21 and
100.80 mg) were separately added to 1000 mL of EC medium, the test substance was
weighed onto a glass slide which was then suspended at the top of the beaker. The
preparations were then stirred for ca 24 hours (with a vortex no deeper than 1 cm),
media were then allowed to settle for ca 1 hour. The final media were then syphoned
from the mid-section (aqueous phase) of the vessels. A control treatment was
prepared in the same manner with EC medium only.
Algae cell counts were performed at 24, 48 and 72 hours during the test.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
The test organism, Pseudokirchneriella subcapitata (Strain 278/4), was originally
obtained from the Culture Collection of Algae and Protozoa (CCAP) and is a
representative species of the freshwater aquatic phytoplankton. This species is
recommended for testing in accordance with the OECD regulatory guidelines.
Prior to testing, duplicate starter cultures were prepared and incubated under test
conditions to obtain sufficient algal cells in exponential
growth and to achieve a starting algae cell density of 1 × 104 cells/mL.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Test temperature:
22.3-23.1°C
Nominal and measured concentrations:
nominal test concentrations of 1.0, 3.2, 10, 32 and 100 mg/L LR WAF (loading rate water
accommodated fraction).
Details on test conditions:
[
Reference substance (positive control):
yes
Remarks:
[State positive control substance]

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 0.599 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 0.604 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: area under the growth curve
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 0.875 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: area under the growth curve
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 0.32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The effects of Dermol OL on the growth of the unicellular green alga,
Pseudokirchneriella subcapitata, were determined during a 72-hour growth inhibition
toxicity test conducted in accordance with OECD Chemicals Testing Guideline
No. 201 Alga, Growth Inhibition Test (adopted 23 March 2006) (Annex 5 corrected
28 July 2011)



Given that the test substance is a multi-constituent substance, the results are based on
nominal loading rates.
Based on nominal loading rate concentrations, the 72-hour EyL50 and ErL50 values
were calculated to be 27.9 mg/L and 50.1 mg/L, respectively.
The corresponding NOEL values for yield and specific growth rate after 72 hours
were 10 and 32 mg/L, respectively.
All validity criteria were met therefore the test was considered valid.



Executive summary:

The objective of the study was to determine the effects of the test substance against

algal growth by exposing the green alga, Pseudokirchneriella subcapitata, at the

exponential growth phase to the test substance during a 72-hour test period.

The test was conducted in accordance with OECD Chemicals Testing Guideline No.

201. Alga, Growth Inhibition Test (adopted 23 March 2006, Annex 5 corrected 28

July 2011).

The test substance Dermol OL is a multi-constituent substance with low water

solubility and as such falls into the category of a “difficult substance” as defined by

the OECD Guidance Document (OECD Series on Testing and Assessment, No. 23

(2000); Guidance Document on Aquatic Toxicity Testing of Difficult Substances and

Mixtures). Based on the recommendations of this guideline, the test substance was

prepared as Water Accommodated Fractions (WAFs).

Based on the results of a range-finding test and two initial definitive test, for which

the key results only have been reported, the definitive test was conducted at nominal

test concentrations of 1.0, 3.2, 10, 32 and 100 mg/L LR WAF (loading rate water

accommodated fraction). Six replicate vessels were prepared for the control and three

replicate vessels were prepared for the test concentrations.

Test vessels (250 mL conical flasks) were prepared containing 100 mL of the

appropriate test or control medium. Each test vessel was inoculated with

1 × 104 algae cells/mL and incubated at 21 – 24°C (under 4440 – 8880 Lux light

intensity) for 72 hours with cell counts at 24-hour intervals.

Chemical analysis was conducted on fresh media at 0 hours and the corresponding old

media at 72 hours. Analysis of the test samples at 0 and 72 hours are summarised in

the table below.

Given that the test substance is a multi-constituent substance, the results are based on

nominal loading rates.

Nominal Concentration(mg/L)                                          Measured Concentration (mg/L)

0 hours (new)                                                                                                         72 hours (old)

Control                                                                                    -                                                                                                                                  -

1.0                                                                                           0.0150                                                                                                                        <LOQ

3.2                                                                                           0.0710                                                                                                                        <LOQ 10                                                                                            0.0302                                                                                                                        <LOQ

32                                                                                            0.104                                                                                                                           <LOQ

100                                                                                           0.366                                                                                                                             0.348

LOQ = 0.005 mg/L (LOQ = limit of quantification)

- None detected

The 72-hour yield (EyLx), area under the growth curve (EbLx) and growth rate (ErLx)

toxicity values, with corresponding no observed effect loading rates (NOEL) are

presented in the table below.

 Parameter

  72 hours

Confidence limits (LUL-UCL)   Statistical test
 Growth rate

ErL10

ErL20

ErL50

NOEL

18.7

33.0

50.1

 

32

9.4 -33.8

18.9 -38.7

45.0 -55.4 

NC

Liner Interpolatin 

(ICPIN)

Derived empirically

 Yield

 EyL10

EyL20

EyL50

NOEL

11.3

14.2

27.9

10 

Na-14.4 

0.86 -18.6

15.7 -42.8

NC

Liner Interpolation

(ICPIN) 

Derived empirically

NC Not calculated

NA Not applicable

LCL Lower confidence limits

UCL Upper confidence limits

Based on nominal

loading rates, the 72-hour EyL50 and ErL50 values were calculated to

be 27.9 mg/L and 50.1 mg/L, respectively.

The corresponding NOEL values for yield and specific growth rate after 72 hours

were 10 and 32 mg/L, respectively.

All validity criteria were met therefore the test was considered valid.

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