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Toxicity to soil microorganisms

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Description of key information

NOEC (40d) = 100 mg/kg (nominal) for respiration inhibition of mixture of sewage sludge compost and sandstone (read across)

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:
100 mg/kg soil dw

Additional information

Since no study assessing the toxicity of Benzaldehyde, 2-hydroxy-5-dodecyl, oxime, branched (CAS 1233873-37-4) to soil microorganisms is 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 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 Phenol, 4-nonyl-,branched it can be concluded that Phenol, 4-nonyl-,branched exhibit a higher aquatic toxicity compared to Benzaldehyde, 2-hydroxy-5-dodecyl, oxime, branched (see table below). Therefore, using data from Phenol, 4-nonyl-,branched to assess the intrinsic hazard of Benzaldehyde, 2-hydroxy-5-dodecyl, oxime, branched is considered to be a very conservative approach (worst case scenario).

Substance

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

Phenol, 4-nonyl, branched*

CAS number

1233873-37-4

84852-15-3

Structure

see attachment (chapter 6.3)

 see attachment (chapter 6.3)

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

-

non-adapted inoculum:

0 % in 28 days (OECD 301B)

 

adapted inoculum:

48.2-62 % in 28 days (OECD 301B)

Adsorption [log KOC]

4.4 (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

 

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 (Trocme et al. 1988). An aged mixture of sewage sludge compost and sandstone was used as inoculum. Respiration (CO2 evolution) was recorded daily throughout the test period. Respiration started at the same rate (37 µg C/g organic C per h) in control and treatments. The rates then decreased progressively, indicating depletion of easily mineralizable C and N. CO2 evolution did not differ significantly between the 100 ppm samples and the controls. In contrast, 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 the reasons given above this value is considered to be sufficiently conservative to be used for the hazard assessment of Benzaldehyde, 2-hydroxy-5-dodecyl, oxime, branched (CAS 1233873-37-4).

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