6-cyclohexyl-1-hydroxy-4-methylpyridin-2(1H)-one, compound with 2-aminoethanol (1:1)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

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 301

Principles of method if other than guideline:

Data published on ready biodegradation studies (OECD 301) for 2-aminoethanol, neutral form of ethanolaminium cation.

GLP compliance:

not specified

Remarks:

Data published. No detailed information about GLP compliance.

Inoculum or test system:

not specified

Parameter:

other: Ready Biodegradability

Remarks on result:

other: Ready Biodegradable

Interpretation of results:

readily biodegradable

Conclusions:

Ethanolaminium cation is considered as ready biodegradable, based on results of several ready biodegradation studies (OECD 301) available for its neutral form 2-aminoethanol (CAS number: 141-43-5;SIDS INITIAL ASSESSMENT PROFILE, OECD 2013). In water at environmentally relevant pH 2-aminoethanol will exist as ethanolaminium cation.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

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 301

Principles of method if other than guideline:

Data published on ready biodegradation studies (OECD 301) for Ciclopirox, neutral form of 6-cyclohexyl-4-methyl-2-oxopyridin-2(1H)-olate anion.

GLP compliance:

not specified

Remarks:

Data published. No detailed information about GLP compliance.

Inoculum or test system:

not specified

Parameter:

other: Ready Biodegradability

Remarks on result:

other: not ready biodegradable

Validity criteria fulfilled:

not specified

Interpretation of results:

not readily biodegradable

Conclusions:

6-cyclohexyl-4-methyl-2-oxopyridin-2(1H)-olate anion is considered as not ready biodegradable, based on the result of a ready biodegradation study (OECD 301) available for its neutral form Ciclopirox. Within the environmentally relevant pH range, a substantial fraction of 6-cyclohexyl-4-methyl-2-ox opyridin-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)).

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 biodegradation in water was focused on dissociation products.

Ethanolaminium cation is considered as ready biodegradable, based on results of several ready biodegradation studies (OECD 301) available for its neutral form 2-aminoethanol (CAS number: 141-43-5). In water at environmentally relevant pH 2-aminoethanol will exist as ethanolaminium cation.

6-cyclohexyl-4-methyl-2-oxopyridin-2(1H)-olate anion is considered as not ready biodegradable, based on the result of a ready biodegradation study (OECD 301) available for its neutral form Ciclopirox. 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 biodegradation of its dissociation products, Ciclopirox olamine is regarded as not biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed