Hexahydro-2H-azepin-2-one, sodium salt

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

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
Please refer to the Read-across Statement attached in Section 13.2.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The underlying hypothesis for the read-across is that the target substance is very prone to hydrolysis resulting in the formation of epsilon-caprolactam and sodium hydroxide. As hydrolysis of the target substance will inevitably occur both under physiological and under environmental conditions, the evaluation of the data of epsilon-caprolactam and sodium hydroxide is considered to be sufficient for hazard assessment. Thus, the toxicological behavior of BRUGGOLEN® C10 can be considered to be determined by the hydrolysis products caprolactam and caustic soda.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Target substance: sodium caprolactamate, CAS-No. 2123-24-2 (for detailed composition please refer to the Read-across Statement attached in Section 13.2)
Source substances: epsilon-caprolactam, CAS-No. 105-60-2 and sodium hydroxide, CAS-No. 1310-73-2

3. ANALOGUE APPROACH JUSTIFICATION
The justification of the read-across hypothesis is mainly based on the hydrolysis of the target substance into the source substances.
BRUGGOLEN® C10 is a combination of sodium caprolactamate (17 – 20 %) and epsilon-caprolactam (80 – 83 %). If diluted in water, sodium caprolactamate easily degrades to caprolactam and sodium hydroxide (caustic soda). Reason is the instability of the ionic N-Na-bond of the sodium caprolactamate.
Thus, the toxicological behavior of BRUGGOLEN® C10 can be considered to be determined by the hydrolysis products caprolactam and caustic soda.

4. DATA MATRIX
Please refer to the Read-across Statement attached in Section 13.2.

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Description of key information

Algae toxicity, freshwater, acute > 1.000 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

1 000 mg/L

EC10 or NOEC for freshwater algae:

1 000 mg/L

Additional information

Data obtained by Read-Across from ε-caprolactam:

A study with epsilon-Caprolactam (GLP) according OECD 201 performed at the Mitsubishi Chemical Safety Institute on behalf of the Ministry of Environment, Government of Japan with Pseudokirchneriella subcapitata as test species resulted in a NOEC (72h) of 1,000 mg/l and an EC50 (72h) >1,000 mg/l.

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Data obtained by Read-Across from sodium hydroxide:

The hazard of NaOH (not neutralized) is caused by the hydroxyl ion (pH effect).