Aminocaproic acid

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

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
The source substance is the cyclic epsilon-caprolactam, which converts in aqueous solution to the linear 6-aminocaproic acid by hydrolytic ring-opening (Tirrell et al., 1975). Hence, 6-aminocaproic acid will be present regardless whether epsilon-caprolactam or 6-aminocaproic acid was used as test material. Moreover, hydrolysation of epsilon-caprolactam to 6-aminocaproic acid is to be expected in aquatic environmental systems, which allows the read across between the two test materials.

Cited literature:
M. V. Tirrell, G. H. Pearson, R. A. Weiss and R. I. Laurence: An Analysis of Caprolactam Polymerisation. Polymer Engineering and Science, May, 1975, Vol. 15, No. 5, Pages 386 - 393.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The source substance epsilon-caprolactam, CAS 105-60-2, which was used in the most current acute toxicity test with Daphnia magna (reference 6.1.3-1), had a analytical purity of 99.9 %. No information on impurities is available. The target substance 6-aminocaproic acid, CAS 60-32-2, had a purity of >= 98 % (w/w). Thus, the purity of the test materials is comparable.

3. ANALOGUE APPROACH JUSTIFICATION
Experimental data i.e. acute toxicity studies with Daphnia magna were available for epsilon-caprolactam. Epsilon-caprolactam was tested in an study according to OECD 202. This study revealed an EC50 of > 1000 mg/L. The information given on epsilon-caprolactam is considered to be sufficient to cover the required endpoint information for the target substance 6-aminocaproic acid.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Description of key information

In a read across with the source substance epsilon-caprolactam (CAS 105-60-2), the EC50 (48h) of the target substance 6-aminocaproic acid (CAS 60-32-2) was determined to be >1000 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 000 mg/L

Additional information

No data on toxicity to aquatic invertebrates were available for the substance 6-aminocaproic acid (CAS 60-32-2) itself. Therefore, a read across to the close structural analogue epsilon-caprolactam (CAS 105-60-2) was conducted.

Key study

In a static GLP-compliant study according to OECD guideline 202 with the structural analogue epsilon-caprolactam (CAS 105-60-2), the EC50 (48h) of the test item was determined to be >1000 mg/L (reference 6.1.3-1).

Conclusion

The toxicity of 6-aminocaproic acid (CAS 60-32-2) to aquatic invertebrates was assessed in a read across to the structural analogue epsilon-caprolactam (CAS 105-60-2). Based on the most current and reliable information (reference 6.1.3-1), the EC50 (48h) of the target substance 6-aminocaproic acid (CAS 60-32-2) was determined to be > 1000 mg/L.