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

Biodegradation in water and sediment: simulation tests

Description of key information

DT50 ~ 58 days in seawater. Lack of oxygen reduced the degradation rate by half in the presence of sediment (read across).

Additional information

Since no simulation studies assessing the biodegradability of Benzaldehyde, 2-hydroxy-5-dodecyl, oxime, branched (CAS 1233873-37-4) in water and sediment are available, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of substances, a read-across to Phenol, 4-nonyl-,branched (CAS 84852-15-3) was conducted, which is structurally similar to the main component of the substance. The structural difference between the source substance and the target substance is the lack of a aldoxime group at the phenol ring of the molecule and a C9 branched carbon chain instead of a C12 branched carbon chain. The read across is justified by similarity of structure and functional groups and accordingly similar physico-chemical properties, which is expected to result in similar environmental behavior and fate (see table).

Substance	Benzaldehyde, 2-hydroxy-5 -dodecyl, oxime, branched	Phenol, 4-nonyl, branched^*
CAS number	1233873-37-4	84852-15-3
Structure	see attachment (chapter 6.1)	see attachment (chapter 6.1)
Molecular formula	C19H31N1O2	C15H24O
Molecular weight	~ 305.46 g/mole	~ 220.35 g/mole
PC parameter
Water solubility	0.3 mg/L (OECD 105)	5.7 mg/L (ASTM E 1148-02)
Partition coefficient	> 5.7 (EU method L3B3 A/63 -73)	5.4 (OECD 117)
Vapour pressure	< 0.39 Pa at 20 °C (estimation based on Grain-Watson method)	~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]	-	0.05 – 0.22 mg/L (different methods)
Long-term toxicity to aquatic invertebrates [NOEC]	-	0.006 mg/L (ASTM E 1241-05)
Short-term toxicity to aquatic invertebrates [48h-EC50]	-	0.08 – 0.14 mg/L (different methods)
Long-term toxicity to aquatic invertebrates [21d-NOEC]	-	0.024 - 0.116 mg/L (different methods)
Short-term toxicity to algae [72h-EC50]	498.32 mg/L (OECD 201)	0.33 - 1.3 mg/L (different methods)
Long-term toxicity to algae [72h-NOEC/EC10]	101.2 mg/L (OECD 201)	0.5 mg/L (Algal growth inhibition test according to UBA 1984)
Toxicity to microorganisms [EC50]	-	950 mg/L (OECD 209)

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

 

Several water/sediment - simulation studies with 4-nonylphenol are available in the literature. However, only one study clearly indicated that branched nonylphenol was tested. Ekelund et al. (1993) studied the biodegradation of 4-nonylphenol in seawater and sediment using a test design similar to OECD guideline 309. In the experiments 14C uniformly ring-labelled nonylphenol (synthesized using nonene containing a mixture of branched isomers) was used. The reaction flasks used contained seawater or seawater plus sieved soft bottom sediment. Formalin was added to four flasks containing seawater and half of the flasks containing seawater and sediment were bubbled with nitrogen gas prior to the start of the experiment. 11 µg 14C ring-labelled nonylphenol was dissolved in acetone and added to small glass plates, the solvent was then evaporated and the glass plates added to the reaction flasks. The flasks were incubated at 11 ± 2 °C in the dark for 16 weeks. In flasks containing formalin no 14CO2 was recovered, indicating that any 14CO2 must come from the nonylphenol in the presence of living organisms. In the absence of sediment, degradation (as measured by 14CO2 production) was very slow at 0.06% per day up to 28 days than 1% per day after 28 days, suggesting a period of adaptation is required. In the presence of sediment the degradation rate was faster at 1.2% per day. In the low oxygen experiments the reaction rate was slow. The increase in degradation rate in the sediment system was attributed to the higher number of microorganisms present. The overall recovery of 14C from these experiments was around 64% (44% in the CO2 fraction) in the flasks without sediment and 49% (46% in the CO2 fraction) in the flasks with sediment. Thus, around 45% of the ring-label was converted to CO2 in 8 weeks, giving a mineralization half-life of slightly longer than 56 days (~ 58d). Lack of oxygen reduced the degradation rate by half in the presence of sediment. However, the low overall recovery of 14C-label in the experiments indicates that the actual extent of biodegradation may be higher (with a resulting shorter half-life) than implied by the 14CO2 measurements (for example incorporation of the 14C-label into biomass may have occurred.In conclusion, branched nonylphenol is considered to be inherently biodegradable in marine water and sediment. Based on the reasons given above this conclusion is also considered to be true for Benzaldehyde, 2-hydroxy-5 -dodecyl, oxime, branched (CAS 1233873-37-4).