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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)
Adequacy of study:
key study
Study period:
1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study was conducted according to OECD guideline 201 as well as in compliance with GLP with acceptable restrictions. Chemical analyses were not performed.
Justification for type of information:
Direct read-across from C16 TMAC to Cetrimonium chloride is claimed as valid because they are both trimmoniums sharing a common alkyl chain length n=16. C16 TMAC is also known as the cetrimonium ion, exhibts properties and effects consistent with a category of quaternary ammonium compounds known as the alkyl trimoniums. C16 TMAC is commonly known as the cetrimonium ion. In pure form QACs also contain an anion such as chloride, bromide or methosulfate. When in solution the substances will be dissociated and the anion the QACs were once associated with will be irrelevant.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
KH2PO4 and NaHCO3 concentrations were 160 and 100 mg/L
GLP compliance:
yes
Specific details on test material used for the study:
Substance type: Quaternary ammonium compound; surfactant- Physical state: Solid- Analytical purity: >97%- Lot/batch No.: G4 2892- Stability under test conditions: stable- Storage condition of test material: ambient conditions in the dark
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
A stock solution of 1 g/L was prepared in deionised water. Test solutions were prepared by dilution of the stock solution in OECD medium.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Common name: Selenastrum capricornutum ATCC 22662- Source (laboratory, culture collection): ATCC- Age of inoculum (at test initiation): exponentially growing - Method of cultivation: identical as during the test
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
Standard OECD medium
Test temperature:
22.5 - 23°C
pH:
6.8 - 7.6
Dissolved oxygen:
-
Salinity:
Standard OECD medium
Nominal and measured concentrations:
Nominal: 0, 0.01, 0.02, 0.04, 0.08 and 0.16
Details on test conditions:
The culturing apparatus was a cabinet in which the temperature was maintained between 22 and 24°C, and continuous uniform illumination was provided in the spectral range of 400 to 700 m. The light intensity is in the range of 6000 to 10000 lux which is obtained by using seven 30 W fluorescenr lamps (colour temperature of approximately 4300 K), at a distance of 0.35 m from the algal culture. The culture flasks were rotated continuously at 100 rpm to prevent sedimentation of the algae.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate 99.5% purity lot H0234 JT baker
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.08 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 0.07 - 0.08 mg/L 95% confidence limits
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.05 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 0.04 - 0.05 mg/L 95% confidence limits
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.04 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: growth and growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.047 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Results with reference substance (positive control):
The absorbance measurement data of potassium dichromate included in the report. From results, an ErC50 and EbC50 (0-72 h) of potassiumdichromate of 0.57 and 0.23 mg/L, respectively, was calculated. These values of the reference compound were in accordance with data of an international interlaboratory test showing that the test organisms have not changed significantly and that the slight modification of the mineral salts medium do not influence the result.
Reported statistics and error estimates:

The EC50 values were computed from the best fitted line (least square method) through the points given by the probit of the percentage inhibition and the logarithm of the concentration of the test substance. The EC50 value calculated with the area under the growth curve is termed EbC50 (0-72 h) whereas the EC value calculated with the specific growth rate is termed ErC50. Confidence limits were computed based on Fieller's theorem. All computations were performed with a programme (Akzo programme, Algal version 1.0) using the software package SAS.
Validity criteria fulfilled:
yes
Remarks:
but no chemical analysis was performed
Conclusions:
Under the study conditions, the EbC50 (0 -72 h) and ErC50 of test substance for Selenastrum capricornutum were 0.05 and 0.08 mg a.i./L, respectively. The NOEC for effect on algal growth and growth rate was determined to be 0.04 mg/L.

Based on read-across from TMAC C16, and using the category approach for alkyl trimmoniums, this result is deemed valid for cetrimonium chloride.
Executive summary:

The NOEC for effect on algal growth and growth rate was determined to be 0.04 mg a.i./L and the ErC10 value was 0.047 mg a.i./L. This ErC10 with a value of 0.047 mg/L is just a bit higher than the NOEC. The CV is now much higher than the max of 35% indicating that this study is based on the 2008 criteria not valid. Also here  there is only one value which gives a partial response indicating that the test concentrations chosen were too widely distributed.

Description of key information

In a study using the read-across source, C12 -18 TMAC, under the study conditions, the EbC50 (0 -72 h) and ErC50 of test substance for Selenastrum capricornutum were 0.05 and 0.08 mg a.i./L, respectively. The NOEC for effect on algal growth and growth rate was determined to be 0.04 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.08 mg/L

Additional information