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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
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar toxicological properties because
• they are manufactured from similar or identical precursors under similar conditions
• they share structural similarities with common functional groups: quaternary ammonium and saturated or unsaturated alkyl chains with comparable length (corresponding to scenario 2 of the read-across assessment framework)

The read-across hypothesis is based on structural similarity of target and source substances. Based on available experimental data, including key physicochemical properties and data from acute toxicity, irritation, sensitization (human) and genotoxicity studies, the read-across strategy is supported by a quite similar toxicological profile of all substances.

Therefore, read-across from the existing ecotoxicity, environmental fate and toxicity studies conducted with the source substances is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

A justification for read-across is attached to IUCLID section 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See justification for read-across attached to IUCLID section 13.

3. ANALOGUE APPROACH JUSTIFICATION
See justification for read-across attached to IUCLID section 13.

4. DATA MATRIX
See justification for read-across attached to IUCLID section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Water media type:
freshwater
Duration:
5 d
Dose descriptor:
NOEC
Effect conc.:
0.031 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
cell number
Remarks on result:
other: Water from White river: pH 7.3, 299 mg/L CaCO3, 68 mg/L suspended solids
Duration:
5 d
Dose descriptor:
EC50
Effect conc.:
0.03 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: extrapolated based on differences in QSAR estimation

Description of key information

EC50 = 30 µg/L, 5 d NOEC = 31 µg/L (read-across from DODMAC and DHTDMAC)

Key value for chemical safety assessment

EC50 for freshwater algae:
30 µg/L
EC10 or NOEC for freshwater algae:
31 µg/L

Additional information

No experimental data are available for the target substance Di-C12-18 alkyldimethyl ammonium chloride. However, toxicity studies in algae are available for the closely related source substances DODMAC and DHTDMAC. A justification for read-across is attached to IUCLID section 13.

 

Several references are cited in EU RAR, 2002:

 “The toxicity of DODMAC for Selenastrum capricornutum and Microcystis aeruginosa in laboratory water was investigated according to an ASTM method (Lewis & Hamm, 1986). For growth reduction after 96h the EC50 was 0.06 mg/l for Selenastrum capricornutum and 0.05 mg/l for Microcystis aeruginosa (nominal concentrations; pH = 6.8 - 7.2, hardness = 131 - 146 mg/l CaCO3).

An algae study with DODMAC in filtered natural water of the Little Miami River, OH (5.4 mg/l total organic carbon, pH = 8.1 - 8.4, hardness = 171 mg/l CaCO3) was conducted by Versteeg & Shorter, 1993. ForSelenastrum capricornutuma 96h EC50 of 1.12 mg/l was derived for growth reduction (measured concentration) and the algistatic concentration was above 16.4 mg/l. In this study acidic methanol was used as carrier solvent, which had a growth stimulating effect on the algae.”

 

“The influence of different test media on the sensitivity of Selenastrum capricornutum towards DHTDMAC (71.4% active ingredient) was investigated by EG & G Bionomics, 1981 b,c,d. Laboratory water with a hardness of 20 mg/l CaCO3 (no further characterization) and algae nutrient enriched White River water (Indiana) of the following quality prior to autoclaving were used: pH = 7.3, total hardness = 299 mg/l CaCO3, 68 mg/l suspended solids, 0.2 µg/l MBAS) In laboratory water a NOEC of 0.078 mg/l and an algistatic concentration of 0.228 mg/l were derived for the reduction of cell number after 5 days (nominal concentrations of active ingredient). The corresponding values for the river water were: NOEC = 0.062 mg/l and algistatic concentration = 0.708 mg/l. The table shows that results for Microcystis aeruginosa are similar (EG & G Bionomics, 1981 b,c,d).” (EU RAR, 2002)

 

Selenastrum capricornutum

 

5d NOEC

5d EC100

5d NOEC

5d EC100

 

0.078 mg/l

0.228 mg/l

0.062 mg/l

0.708 mg/l nominal conc.

laboratory water

"

river water

"

 

Microcystis aeruginosa

 

5d NOEC

5d EC100

5d NOEC

5d EC100

 

0.13 mg/l

0.32 mg/l

0.078 mg/l

0.21 mg/l

nominal conc.

laboratory water

"

river water

"

 

 

The target and the source substances have a low water solubility and form complexes with dissolved organics, especially with anionic compounds. Thus, results with natural river water are considered more realistic and more relevant than the results obtained with laboratory water.

 

For classification and labelling purposes the 96h EC50 of 1.12 mg/L obtained in the river water study conducted with DODMAC cannot be used, as in this study acidic methanol was used as vehicle, which had a growth stimulating effect on the algae. Thus, the EC50 of 0.06 mg/L for Selenastrum capricornutum was used, although this study was conducted in laboratory water.

 

From the QSAR data on short-term toxicity to fish and Daphnia (no model is available for algae) it was deduced, that the target substance should be expected to be more toxic than the source substances DODMAC and DHTDMAC, and a factor of approx. 2 should be applied to the EC50 and NOEC obtained in this study. Thus, the EC50 and NOEC of the target substance Di-C12-18 alkyldimethyl ammonium chloride are considered to be 0.03 and 0.031 mg/L.