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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
migrated information
Adequacy of study:
key study
Study period:
2017
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Justification for type of information:
A test was performed on analogue substance following OECD 202. The results show that the tested item is not toxic to Aquatic algae, ErC50 > 100 mg/L.
Based on the read across consideration the same results apply to Direct Blue 299.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
2011
Principles of method if other than guideline:
The 72 h algal growth inhibition test with Raphidocelis subcapitata
was done according to OECD 201 (2011) and ISO 8692 (2012) guidelines
with slight modifications. Algae were routinely cultured at
25±1 °C with light in Cyanobacteria BG-11 Freshwater Solution. The
culture was split twice a week, adding fresh medium. Algae were exposed
to the treatment in sterile 24-well plates with 2 mL of each
treatment solution to the respective microplate well, for three days.
Untreated ISO formulation freshwater and potassium dichromate (0.10
– 1.8 mg/L) were used as negative and positive controls respectively.
Each treatment was replicated three times and randomized within the
plate. Algal stock solution containing 1.01E6 cells/mL was added
(20 μL) to each well to obtain a starting algal density of 1E4 cells/mL.
Plates were incubated for 72 h at 25±1 °C on an orbital shaker
(90 rpm) in a thermostatic chamber. Light was provided by a 2 W LED
Unit for each plate. Algal density at the beginning and end of treatment
was measured with a TC20™ Automated Cell Counter (Bio-Rad Laboratories,
Inc), selecting a gate of 4–14 μm or by visual scoring with a
Burker's chamber. Results were expressed as effect on biomass (EbC50)
and on growth rate (ErC50).
The procedure was used for both limit tests and concentration-response
studies. For the limit tests, algae were exposed to each dyes at
100 mg/L. Dyes with 72 h NOEbC higher than 100 mg/L were considered
“non-toxic” while dyes with 72 h NOEbC lower than 100 mg/L
were considered “potentially toxic” and further investigated with a full
dose-response curve. Finally, only dyes with 72 ErC50 lower than
100 mg/L were classified as “toxic” according to the OECD guideline.
GLP compliance:
no
Specific details on test material used for the study:
Potassium dichromate and BG-11 medium were purchased from
Sigma (St. Louis, MO, USA). Daphtoxkit F™ magna and ISO algal
medium were purchased from the national distributor of MicroBioTests
Inc. (Belgium). Raphidocelis subcapitata was routinely maintained from
a frozen aliquot generated by algae purchased from the national distributor
of MicroBioTests Inc.
Analytical monitoring:
yes
Vehicle:
yes
Details on test solutions:
BG-11 medium were purchased from Sigma (St. Louis, MO, USA).
Test organisms (species):
other: Raphidocelis subcapitata
Details on test organisms:
Raphidocelis subcapitata was routinely maintained from
a frozen aliquot generated by algae purchased from the national distributor
of MicroBioTests Inc.
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
25±1 °C
Nominal and measured concentrations:
Algal stock solution containing 1.01E6 cells/mL was added
(20 μL) to each well to obtain a starting algal density of 1E4 cells/mL.
Details on test conditions:
Plates were incubated for 72 h at 25±1 °C on an orbital shaker
(90 rpm) in a thermostatic chamber. Light was provided by a 2 W LED
Unit for each plate. Algal density at the beginning and end of treatment
was measured with a TC20™ Automated Cell Counter (Bio-Rad Laboratories,
Inc), selecting a gate of 4–14 μm or by visual scoring with a
Burker's chamber. Results were expressed as effect on biomass (EbC50)
and on growth rate (ErC50).
Reference substance (positive control):
not specified
Duration:
72 h
Dose descriptor:
other: ErC50, Effect on growth rate
Effect conc.:
< 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Results with reference substance (positive control):
Untreated ISO formulation freshwater and potassium dichromate (0.10 – 1.8 mg/L) were used as negative and positive controls respectively.
Validity criteria fulfilled:
not specified
Conclusions:
non toxic
Executive summary:

Direct Blue 293

Limit Test (NOEbC>100)

72 h EC50 with P. subcapitata (mg/L)

   ErC50

 test 1

 146.770

 test 2

 137.975

 test 3

 157.013

Description of key information

Key value for chemical safety assessment

EC50 for freshwater algae:
137.975 mg/L

Additional information

A test was performed on analogue substance following OECD 202. The results show that the tested item is not toxic.

Based on the read across consideration the same results apply to Direct Blue 299.