Phenol, 4-amino-, reaction products with aniline, 4-methyl-1,3-benzenediamine, p-phenylenediamine, sodium sulfide (Na2S) and sulfur

Toxicity to aquatic plants other than algae

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For justification please refer to attached Read Across Statement in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

> 0.023 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

0.023 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Duration:

7 d

Dose descriptor:

LOEC

Effect conc.:

> 0.023 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Description of key information

Based on a WoE approach the test item is considered as non-toxic to Lemna gibba:

- the test item is insoluble (< 0.1 mg/L) in the Lemna gibba test medium

- it is unlikely that the test item passes biological membrans due to its high molecular weight (>> 1000 Da)

- the read across substance Leucosulphur Yellow 22 was not toxic to Lemna gibba in an OECD TG 221 study.

Additional information

Weight of evidence (WoE) to conclude on the toxicity of Leucosulphur Green 16 on aquatic plants

Leucosulphur Green 16 is insoluble in the Lemna giba test medium (< 0.1 mg/L, see "analytical methods", IUCLID section 8).

Furthermore, it its unlikely that Leucosulphur Green 16 can cross biological membranes due to its very high molecular weight (number-average molecular weight: >> 10 000 Da and weight-average molecular weight (Mw) >> 100 000 Da, see read- across justification document).

In a Lemna sp.growth inhibition test according to OECD Guideline 221 and Commission Regulation (EC) No 761/2009, Annex VI, C.26 with a WAF, the 7 -d EC50 and the NOEC of the read-across substance Leucosulphur Yellow 22 (CAS 990268 -98 -7) were higher than the solubility level of the test item in the test medium, which corresponds to a mean measured concentration of 0.023 mg/L (EC50: >100 mg/L nominal). This study is summarized below.

Considering the above information in a weight of evidence approach, it is concluded that Leucosulphur Greeen 16 is not toxic to aquatic plants.

Summary of the OECD TG 221 study on Lemna gibba with the read-across substance Leucosulphur Yellow 22

The toxicity of the test item to aquatic plants was assessed in a GLP-compliant Lemna sp. Growth Inhibition Test according to OECD Guideline 221 and Commission Regulation (EC) No 761/2009, Annex VI, C.26. Exponentially-growing cultures of Lemna gibba were exposed to the nominal concentration of 100 mg/L (highest concentration to be tested according to OECD 221) of the test item. Due to the low solubility of the test item, test solutions (six replicates) were prepared by utilizing the water accommodated fraction (WAF) approach method (according to OECD Series on Testing and Assessment No. 23). In addition a negative control (20 X AAP Medium; six replicates) and a positive control with the reference substance 3,5-dichlorophenol was performed. 400 mL Petri dishes-covered glass beakers were filled with 160 mL testing solutions. TwoLemna gibbacolonies with four, and one colony with three fronds were added to each vessel. Visual assessment of growth and morphological changes was conducted on days 3, 5 and 7. As the test item is not stable for the duration of 7 days in 20 X AAP medium, the test and control solution were renewed twice during the test (on days 3 and 5). The test item concentration was measured by UV-Vis to be 0.023 mg/L (arithmetric mean). In result, the 7-d EC50 and NOEC of the test item was determined to be > 0.023 mg/L (arithmetric mean measured). The doubling time of frond number in the control was 1.90 days (less than 2.5 days). Thus, the validity criterion of the test guidelines was within the acceptable limit and therefore the study can be considered as valid.