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Toxicity to terrestrial arthropods

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Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline available
Principles of method if other than guideline:
Study on the effect of increasing NP concentrations in soil microcosms containing a simplified soil community over a test period of 112 days.
GLP compliance:
not specified
Application method:
soil
Analytical monitoring:
no
Vehicle:
no
Details on preparation and application of test substrate:
- Method of mixing into soil (if used): Due to its high hydrophobicity, different solutions of 4-nonylphenol in acetone (95%, Panreac, Barcelona, Spain) were prepared in order to achieve different soil concentrations (0, 10, 30, 90, and 270 mg/kg of soil). For each concentration, the soil was hydrated with a fixed volume of acetone solution containing the appropriate quantity of NP (150 mL of solution per kilogram of soil), a rate which permitted proper spiking of the chemical solution with soil. An equal acetone solution volume was applied to all the test concentrations. Pure acetone was added for the controls. The acetone was then left to evaporate for 24 h in a fume hood. For each concentration prepared, a small portion of the untreated soil (20%) was put aside to be used as microbial inoculums prior to the addition of the acetone solution. Once the acetone had evaporated and just before the beginning of the experiment, this soil portion was mixed with the polluted soil in order to reinoculate it with the original microbial soil community. Just before the construction of the microcosms, the soil batches were hydrated to 25% (corresponding to 45% of their water holding capacity). This moisture corresponded to the maximum water content that allowed this soil to have a crumbly structure, due to its loamy nature.
Test organisms (species):
other: simplified soil community (microorganisms, seedling of Avena sativa), Porcellionides sexfasciatus, Enchytraeus crypticus, Folsomia candida, Ceratophysella denticulata, Proisotoma minuta, Hypoaspis aculeifer)
Animal group:
other: microorganism, plant, nematod, collembolan, isopod, mite
Details on test organisms:
The microcosms consisted of an assemblage of cultured organisms which mimicked a soil invertebrate food web. Decomposers were represented as the natural microbial community, since spiked soil was reinoculated with unspiked soil just before the start of the experiment, as described above. As primary producers, only one seedling of common oats (Avena sativa) was used per microcosm, due to the small size of the containers and in order to prevent excessive root growth in the soil. As detritivores (consumers), four species belonging to three different functional groups were used. Isopods of the species Porcellionides sexfasciatus (Crustacea, Isopoda, Oniscidea) represented the macrofauna living on the soil surface. The individuals came from a laboratory culture initially started with wild individuals collected in southern Portugal (São Domingos, Alentejo, Portugal). As representatives of the mesofauna, three collembolan species and an enchytraeid were introduced into the microcosms. The collembolan species used were F. fimetaria (Collembola, Isotomidae), Proisotoma minuta (Collembola, Isotomidae), and Ceratophysella (Hypogastrura) denticulata (Collembola, Poduridae). All these species were cultured in the laboratory for at least 3 years and were obtained, respectively, from the National
Environmental Research Institute (Silkeborg, Denmark), from an earthworm culture in our laboratory, and from the collembolan “bloom” of an agricultural soil in central Catalonia (NE Spain). Enchytraeus crypticus (Oligochaeta, Enchytraeidae) were also bred in our laboratory and used as a representative of soil enchytraeids. Finally, as a representative of soil predators, mites of the species Hypoaspis aculeifer (Acari, Gamasidae), provided by ECT Oekotoxikologie GmbH (Flörsheim, Germany), were introduced into the microcosms. All the soil species selected are able to carry out sexual reproduction, an important feature for the chemical assessed in this study, as it is alleged to have estrogenic effects as its main toxicity mechanism.
Study type:
semi-field study
Limit test:
no
Total exposure duration:
112 d
Test temperature:
20 ± 0.1 °C
pH (if soil or dung study):
8.3
Humidity:
70% relative humidity
Photoperiod and lighting:
16h light/ 8h dark
Details on test conditions:
TEST SYSTEM
- Test container (material, size): plastic transparent polyethylene terephthalate bottles (16 cm in height and 8.5 cm in diameter) with open tops.
- Amount of soil or substrate: Each container was filled with 2 cm of quartz sand which, together with several holes in the basis of the container, allowed proper drainage of any excess water. Each container was then filled with 300 g of wet soil (previously contaminated), which produced a soil layer of around 10 cm.
- No. of organisms per container (treatment): The soil was then sown with five common oat seeds, and the NP was left to stabilize for 24 h. The oat seeds germinated approximately 4 days later. The day after setting up the microcosms (day 1), three adult isopods (P. sexfasciatus) per microcosm were added, one ma and two nonpregnant females. A single alder leaf (Alnus glutinosa) was also added to each microcosm, all with a similar weight. The leaves had previously been dried at 80°C for 24 h. The leaves were used as a food source by the isopods, thus minimizing the consumption of oat seedlings. On the same day, 15 adult individuals of P. minuta and 15 adult individuals of C. denticulata were added to each microcosm. The individuals came from mixed-age laboratory cultures and were selected randomly in order to provide similar sex ratios and adult age classes to all the microcosms. On day 2, ten adult enchytraeids (clearly identified by the clitellum) and 15 adult collembolans (F. fimetaria) were added to each microcosm. On day 6, six adult mites (H. aculeifer), three males and three females, were added to each microcosm. The reason for the delay in the addition of the mites was to allow the collembolans and the enchytraeids to reproduce and ensure their performance in the microcosms but also to minimize any starvation period for the mites. On the same day, all the oat seedlings in each microcosm were removed except one, which was the most vigorous plant.
- No. of replicates per treatment group: 15
- No. of replicates per control: 15

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
The soil used in the microcosms was the upper layer (20 cm) of a loamy natural soil collected from an experimental agricultural soil within the campus of the Autonomous University of Barcelona (Cerdanyola del Vallès, Spain). The soil had formerly been used for grain production and had been free of pesticides for at least 5 years. After collection, the soil was air-dried for a week and sieved (5 mm). To remove the natural invertebrate communities that could influence the results, the soil was defaunated by two consecutive freezing–thawing cycles, each consisting in placing soil at −20°C for 4 days followed by a period of 4 days at 20°C.
- % sand: 36.4
- % silt: 44.9
- % clay: 18.7
- Organic carbon (%): 2.63
- CEC: 13.9 meq/100g

OTHER TEST CONDITIONS
- Photoperiod: 16h light: 8h dark

EFFECT PARAMETERS MEASURED: Abundances of the different species observed was recorded after 28, 56 and 112 days exposure time.
Nominal and measured concentrations:
Nominal: 10, 30, 90 and 270 mg/kg
Reference substance (positive control):
no
Duration:
112 d
Dose descriptor:
NOEC
Effect conc.:
90 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: abundance
Remarks on result:
other: related to soil community
Details on results:
The results from this study indicate that concentrations above 90 mg NP kg–1 may cause changes in soil invertebrate communities. The maximum concentration tested (270 mg NP kg–1) changed the invertebrate community significantly, although a recovery was observed after 112 days.
Reported statistics and error estimates:
The effects of nonylphenol on the microcosm community over time, that is, the effects of pollution ruling out the community intrinsic temporal changes, were assessed by multivariate analysis, using principal response curves (PRC).
Validity criteria fulfilled:
not applicable
Conclusions:
A 112d-NOEC for a soil community is determined to be 90 mg/kg dw based on abundance in a semi-field study (microcosms).
Executive summary:

The effect of increasing 4-nonylphenol (NP) concentrations (0, 10, 30, 90, and 270 mg/kg) in soil microcosms containing a simplified soil community was investigated over three sampling dates (28, 56, and 112 days) using the principal response curves method. The soil community did not change significantly at concentrations below 90 mg/kg, which was selected as the nonobserved effect concentration (NOEC). The highest concentration (270 mg/kg) changed the community significantly after 28 and 56 days, but this effect disappeared after 112 days.

Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
see Analogue justification document in chapter 13
Reason / purpose for cross-reference:
read-across source
Key result
Duration:
112 d
Dose descriptor:
NOEC
Effect conc.:
90 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: abundance
Remarks on result:
other: related to soil community

Description of key information

NOEC (112d) = 90 mg/kg dw (nominal) for soil comunity (semi-field study, read across)

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:
90 mg/kg soil dw

Additional information

Since no study assessing the long-term toxicity of Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched (CAS 244235-47-0) to terrestrial arthropods 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 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 a ketoxime 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 Phenol, 4-nonyl-,branched it can be concluded that Phenol, 4-nonyl-,branched exhibit a higher aquatic toxicity compared to Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched (see table below). Therefore, using data from Phenol, 4-nonyl-,branched to assess the intrinsic hazard of Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched is considered to be a very conservative approach (worst case scenario).

Substance

Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched

Phenol, 4-nonyl, branched*

CAS number

244235-47-0

84852-15-3

Structure

see attachment (chapter 6.3)

 see attachment (chapter 6.3)

Molecular formula

C17H27NO2

C15H24O

Molecular weight

~ 277 g/mole

~ 220.35 g/mole

PC parameter

 

 

Water solubility

> 0.02 < 1 mg/L (EU method A.6)

5.7 mg/L (ASTM E 1148-02)

Partition coefficient

> 5.7(EU method A.8)

5.4 (OECD 117)

Vapour pressure

< 1.5 Pa at 20 °C (OECD 104)

~1 Pa at 20 °C (ASTM-D 2879)

Environmental fate

 

 

Biodegradability

1 % in 28 days (BODIS)

non-adapted inoculum:

0 % in 28 days (OECD 301B)

 

adapted inoculum:

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

Adsorption [log KOC]

3.9 (OECD 121)

4.35 - 5.69 (EPA OTS 796.2750)

Hydrolysis

not relevant

Ecotoxicology

 

 

Short-term toxicity to fish

[96h-LC50]

0.46 mg/L (EU method C.1)

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]

9.55 mg/L (OECD 202)

0.08 – 0.14 mg/L (different methods)

Long-term toxicity to aquatic invertebrates

[21d-NOEC]

2.8 mg/L (OECD 211)

0.024 - 0.116 mg/L (different methods)

Short-term toxicity to algae

[72h-EC50]

760 mg/L(OECD 201)

0.33 - 1.3 mg/L (different methods)

Long-term toxicity to algae

[72h-NOEC/EC10]

472 mg/L (OECD 201)

0.5 mg/L (Algal growth inhibition test according to UBA 1984)

Toxicity to microorganisms

[EC50]

> 1000 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 effect of increasing 4-nonylphenol (NP) concentrations (0, 10, 30, 90, and 270 mg/kg) in soil microcosms containing a simplified soil community was investigated over three sampling dates (28, 56, and 112 days) using the principal response curves method (Domene et al.2010). The soil community did not change significantly at concentrations below 90 mg/kg, which was selected as the nonobserved effect concentration (NOEC). The highest concentration (270 mg/kg) changed the community significantly after 28 and 56 days, but this effect disappeared after 112 days.

Based on the reasons given above this value is considered to be sufficiently conservative to be used for the hazard assessment of Ethanone, 1-(2-hydroxy-5-nonylphenyl)-, oxime, branched (CAS 244235-47-0).