Benzaldehyde, 2-hydroxy-5-nonyl-, oxime, branched

Endpoint summary

Description of key information

Soil macroorganisms are the most susceptible terrestrial organism group and the available 28d-EC10 = 94 mg/kg dw (OECD 222) is used for the environmental risk assessment.

Additional information

One study investigating the long-term toxicity of the test substance to soil macroorganisms is available. The 28d-EC10 for reproduction is determined to be 94 mg/kg dw.

Since no studies assessing the toxicity of Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched (C9 Aldoxime, CAS 174333-80-3) to terrestrial plants and microorganisms are available, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of substances, a read-across to 4-nonylphenol was conducted, which is a secondary component and structurally similar to the main component of the substance. The only structural difference between the source substance and the target substance is the lack of an aldoxime group at the phenol ring of the molecule.

The read across is justified due to the following reasons: 

1) The similarity of structure and functional groups and accordingly similar physico-chemical properties result in similar environmental behavior and fate.

2) Based on a profound ecotoxicological data set available for 4-nonylphenol it can be concluded that 4-nonylphenol exhibit an equal to higher aquatic toxicity compared to Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched (see table below and Analogue justification in chapter 13). Therefore, using data from Phenol, 4-nonyl-,branched for the assessment of the intrinsic hazard of Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched is considered to be a conservative approach (worst case scenario)

Substance	Benzaldehyde, 2-hydroxy-5-nonyl, oxime, branched	Phenol, 4-nonyl, branched^*
CAS number	174333-80-3	84852-15-3
Structure	see attachment (chapter 6.3)	see attachment (chapter 6.3)
Molecular formula	C16O2NH25	C15H24O
Molecular weight	~ 263 g/mole	~ 220.35 g/mole
PC parameter
Water solubility	0.4 mg/L (EU method A.6)	5.7 mg/L (ASTM E 1148-02)
Partition coefficient	5.5 (EU method A.8)	5.4 (OECD 117)
Vapour pressure	0.37 Pa at 20 °C (OECD 104)	~1 Pa at 20 °C (ASTM-D 2879)
Environmental fate
Biodegradability	0 % in 28 days (OECD 302c)	non-adapted inoculum: 0 % in 28 days (OECD 301B)   adapted inoculum: 48.2-62 % in 28 days (OECD 301B)
Adsorption [log KOC]	3.7 (OECD 121)	4.35 - 5.69 (EPA OTS 796.2750)
Hydrolysis	not relevant
Ecotoxicology
Short-term toxicity to fish [96h-LC50]	1.1 mg/L (EU method C.1)	0.05 – 0.22 mg/L (different methods)
Long-term toxicity to aquatic invertebrates [NOEC]	0.005 mg/L (OECD 210)	0.006 mg/L (ASTM E 1241-05)
Short-term toxicity to aquatic invertebrates [48h-EC50]	2.7 mg/L (EU method C.2)	0.08 – 0.14 mg/L (different methods)
Long-term toxicity to aquatic invertebrates [21d-NOEC]	0.189 mg/L (OECD 211)	0.024 - 0.116 mg/L (different methods)
Short-term toxicity to algae [72h-EC50]	36.3 mg/L (OECD 201)	0.33 - 1.3 mg/L (different methods)
Long-term toxicity to algae [72h-NOEC/EC10]	14.9 mg/L (OECD 201)	0.5 mg/L (Algal growth inhibition test according to UBA 1984)
Toxicity to microorganisms [EC50]	200.4 mg/L (OECD 209)	950 mg/L (OECD 209)

* Data were taken from Phenol, 4-nonyl-,branched (CAS 84852-15-3) dossier published on the ECHA data base

The toxicity of 4-nonylphenol to terrestrial plants was investigated according to OECD guideline 208 using Lolium perenne and Brassica rapa as test organisms. All 15d-EC50 value showed to be > 1g/kg. 15d-EC10 values are determined to be 574.8 mg/kg for Brassica rapa and 738.9 mg/kg for Lolium perenne, respectively.

In a long-term toxicity test performed similar to OECD guideline 217, soil microbes were incubated with 100 and 1000 ppm branched 4-nonylphenol (NP) over an exposure time of 40 days. An aged mixture of sewage sludge compost and sandstone was used as inoculum. In 1000 ppm samples, CO2 evolution was significantly depressed by the 4th day. Thus, the 40d-NOEC value is determined to be 100 mg/kg dw.

Based on these toxicity data macroorganisms are indicated to be the most susceptible organism group and the available 28d-EC10 value of 94 mg/kg dw was used to derive the PNEC value for the risk assessment. The fact that a more realistic soil microorganism study with 4-Nonylphenol results in similar effect values like the chronic earthworm test with C9 Aldoxime clearly indicate that the 28d-NOEC value with its assessment factor is sufficiently conservative for an environmental risk assessment.