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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
Data published on toxicity studies to aquatic algae for 2-aminoethanol, neutral form of ethanolaminium cation.
GLP compliance:
not specified
Remarks:
Data published. No detailed information about GLP compliance.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.8 mg/L
Nominal / measured:
nominal
Conclusions:
In water at environmentally relevant pH, 2-aminoethanol will exist as ethanolaminium cation. (CAS number: 141-43-5). For 2-aminoethanol, the neutral form of ethanolaminium cation, the lowest reliable toxicity value to aquatic algae is ECr50 (72h) = 2.8 mg/L (nominal; pH 8.0-9.7; Pseudokirchneriella subcapitata).
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Qualifier:
according to guideline
Guideline:
other: OECD 201
GLP compliance:
not specified
Remarks:
Data published. No detailed information about GLP compliance.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.063 mg/L
Nominal / measured:
not specified
Conclusions:
Within the environmentally relevant pH range, a substantial fraction of 6-cyclohexyl-4-methyl-2-oxopyridin-2(1H)-olate anion will be in the neutral form (6-cyclohexyl-1-hydroxy-4-methylpyridin-2-one (Ciclopirox); CAS 29342-05-0; pKa (estimated) = 6.84 (ChemAxon)).
For Ciclopirox, the neutral form of 6-cyclohexyl-4-methyl-2-oxopyridin-2(1H)-olate anion, NOEC (72h) is 0.063 mg/l .

Description of key information

Since Ciclopirox olamine is an organic salt, it is expected to dissociate upon its release in the environment and to dissolve in water into 6-cyclohexyl-4-methyl-2-oxopyridin-2(1H)-olate anion and ethanolaminium cation. Because of this dissociation behaviour, the assessment of Ciclopirox olamine toxicity to aquatic algae was focused on the dissociation products.

For 2-aminoethanol, the neutral form of ethanolaminium cation, the lowest reliable toxicity value to aquatic algae is ECr50 (72h) = 2.8 mg/L (nominal; pH 8.0-9.7; Pseudokirchneriella subcapitata). In water at environmentally relevant pH, 2-aminoethanol will exist as ethanolaminium cation. (CAS number:141-43-5).

For Ciclopirox, the neutral form of 6-cyclohexyl-4-methyl-2-oxopyridin-2(1H)-olate anion, NOEC (72h) is 0.063 mg/l (OECD 201; Pseudokirchneriella subcapitata). Within the environmentally relevant pH range, a substantial fraction of 6-cyclohexyl-4-methyl-2-oxopyridin-2(1H)-olate anion will be in the neutral form (6-cyclohexyl-1-hydroxy-4-methylpyridin-2-one (Ciclopirox); CAS 29342-05-0; pKa (estimated) = 6.84 (ChemAxon)).

Based on experimental data on toxicity to aquatic algae of dissociation products, Ciclopirox olamine is regarded as hazardous for aquatic organisms.

Key value for chemical safety assessment

Additional information