Fatty acids, C16-18, stearyl esters

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:

Refer to the analogue approach justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Water Accommodated Fraction (WAF)

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

Source: RA-A, CAS 93803-87-3, Notox, 1998, S. capricornutum, 72 h

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Water Accommodated Fraction (WAF)

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

Source: RA-A, CAS 93803-87-3, Notox, 1998, S. capricornutum, 72 h

Conclusions:

The key value retained for the toxicity of the target substance to aquatic algae is a NOELR (72 h) of ≥ 100 mg/L and an EL50 (72 h) of > 100 mg/L, based on experimental data with a structurally and chemically closely related source substance (nominal, OECD 201); read-across

Description of key information

No effects up to the limit of water solubility (< 0.05 mg/L, OECD 201, P. subcapitata); read-across

Additional information

There is no study available, in which the toxicity ofthe target substance Fatty acids, C16-18, stearyl esters (CAS 85536-04-5) to aquatic algae was assessed. Therefore, read-across to the structurally and chemically closely related source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was performed in accordance with Regulation (EC) No 1907/2006 Annex XI, section 1.5 in order to fulfill the data requirements for this substance. The source substance is characterized by similar fatty acid chain lengths and alcohol components as the target substance and is therefore considered a suitable representative for the assessment of the toxicity of the target substance to aquatic algae. A detailed read-across justification in provided in IUCLID section 13.

The available study with the source substance 2-octyldodecyl isooctadecanoate was conducted according to OECD guideline 201 and in compliance with GLP. The green algae Pseudokirchneriella subcapitata was exposed to two concentration levels prepared as Water Accommodated Fractions with nominal loading rates of 10 and 100 mg/L test item for 72 h. A chemical analysis of actual test item concentrations in the test solutions was technically not feasible due to the very low water solubility of the test item.

After 72 h, an inhibition of cell growth by 31.2% was observed at the higher testing level of 100 mg/L, whereas no inhibition was observed at the lower testing level of 10 mg/L. The report suggested that the observed inhibition at the higher testing level resulted from insoluble particles of the test item absorbing fractions of light required for normal algal cell growth and concluded that algal growth rate was not affected by the test item, resulting in an EL50 (72 h) of > 100 mg/L and a NOELR (72 h) of ≥ 100 mg/L. Thus, 2-octyldodecyl isooctadecanoate does not cause toxic effects on aquatic algae up to the limit of water solubility.

Based on the high degree of structural and chemical similarity between the target and selected source substance, the target substance is expected to exhibit a similar ecotoxicological profile as the source substance. Therefore, it is concluded that the target substanceFatty acids, C16-18, stearyl esters (CAS 85536-04-5)does not cause toxic effects to aquatic algae upto its limit of water solubility (< 0.507 mg/L, 20 °C, OECD 105).