2,6-dibromo-4-cyanophenyl heptanoate

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to non-target arthropods on natural substrate (NTA other than pollinators)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 Dec, 2013 - 08 Jan, 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 232 (Collembolan Reproduction Test in Soil)

Version / remarks:

1999

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

from State Ministry of the Environment and Agriculture on 18 DEC 2012

Application method:

mixed into substrate

Analytical monitoring:

not required

Vehicle:

no

Details on preparation and application of test substrate:

141 mg a.i./kg soil dry weight:
- 0.0419 g test item was weighed
- Quartz sand was added to a final weight of 11.000 g stock A and stock A was mixed
- 10 g stock A was added to 302.5 g artificial soil and the soil was thoroughly mixed

10 g test item quartz sand mixture containing the required amount of the test item was added to the prepared amount of artificial soil (302.5 g wet weight), resulting in a concentration of 141 mg a.i./kg soil d.w. and yielding 312.5 g wet artificial soil (corresponding to 250 g dry weight) with a final nominal water content of 40-60 % of WHC. The final water content was then checked to be 56.4 – 56.7% of WHC.
Subsequently, 30 g (wet weight) of the treated artificial soil were placed into each test vessel.

Test organisms (species):

Folsomia candida

Animal group:

Collembola (soil-dwelling springtail)

Details on test organisms:

originally purchased from “Biologische Bundesanstalt (BBA)”, Berlin-Dahlem in May 2000 and then breeded in the laboratory.
They were fed with granulated dry yeast
They were 9-12 days (juvenile collembolans)

Study type:

laboratory study

Limit test:

yes

Total exposure duration:

28 d

Test temperature:

18.0 - 21.7 °C

pH (if soil or dung study):

5.87 - 6.08

Humidity:

55.1 % - 56.7 % of the WHC

Photoperiod and lighting:

16h light (570 lux) / 8h dark

Details on test conditions:

Composition of artificial soil:
- 5 % sphagnum peat; classified according to DIN 11540 (as close to pH 5.5-6.0 as possible, no visible plant parts remained, finely ground, dried to measured moisture content)
- 20 % kaolin clay (kaolinite content > 30 %);
- 0.3 % calcium carbonate;
- 74.7 % industrial quartz sand (fine sand is dominant with more than 50 % of the particles between 50 and 200 μm)
- deionised water

Test vessel:
glass container (approximately 150 mL) covered with a glass lid; surface area of soil: 18.9 cm
Amount of soil/test vessel: 30 g wet weight, crumbly structured

Number of collembolans/test vessel (= replicate): 10
Number of replicates/ control group: 8 (+ 2 replicates not loaded with collembolans for measurement purposes)
Number of replicates/ treated group: 8 (+ 2 replicates not loaded with collembolans for measurement purposes)
Number of collembolans/ control group: 80
Number of collembolans/ treated group: 80

Feeding regime: approximately 2 mg granulated dry yeast at the start of the test and after 14 days

Time and parameters:
At test start: Determination of physico-chemical parameters of the artificial soil (water content, pH)

4 weeks after start of exposure: Number of parental and juvenile collembolans per replicate. Observations on obvious physiological or pathological symptoms or distinct changes in behaviour.
Determination of physico-chemical parameters of the artificial soil (water content, pH).

Nominal and measured concentrations:

Nominal conentraion: 141 mg a.i./kg soil dry weight (equivalent to 152.4 mg test item/kg soil dry weight based on analysed purity)

Reference substance (positive control):

yes

Remarks:

Boric acid in a separate study

Toxic reference:

Toxic standard: 44, 67, 100, 150 and 225 mg boric acid/kg d.w; control: quartz sand, solvent control: none.

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 141 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 141 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Details on results:

The test item caused 2.5 % parental mortality at a concentration of 141 mg a.i./kg soil d.w. 2.5 % parental mortality was observed in the control. No statistically significant effect (Fisher`s Exact Binomial Test, α = 0.05, one-sided greater) on parental mortality was found for the concentration tested.
No effects on behaviour of the collembolans were observed during the test.
The mean number of juvenile springtails counted four weeks after introduction of the parental collembolans into the test vessels was 794 in the control and 815 at 141 mg a.i./kg soil d.w. No statistically significant effects (Student-t-test, α = 0.05, one-sided smaller) on the number of juveniles compared to the control group were found at 141 mg a.i./kg soil d.w.

Results with reference substance (positive control):

The EC50 (reproduction) of the reference item boric acid was calculated to be 108 mg a.i./kg soil dry weight. The results of the reference test demonstrate the sensitivity of the test system.

Please refer to "overall remark/ attached background material" field for result tables.

Table 1: Validity criteria for OECD 232 (2016)

Criterion from the guideline to be satisfied in the controls	Outcome	Validity criterion fulfilled
Mean adult mortality over the 4 weeks of the test is ≤ 20%.	2.5 %	Yes
The mean number of juveniles per vessel (with 10 collembolans introduced) should be ≥ 100 juveniles by the end of the test.	794	No
The coefficient of variation calculated for the number of juveniles per replicate is ≤ 30%.	11.6%	Yes

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Conclusions:

The present guideline study was conducted in compliance with GLP. Under the test conditions used, the 28-day NOEC for Folsomia candida was ≥ 141 mg a.i./kg dry soil.

Description of key information

From the key study, the 28 -day NOEC for terrestrial arthropods exposed to the present test material was ≥141 mg a.i./kg dry weight soil.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:

141 mg/kg soil dw

Additional information

There are three GLP-studies available for toxicity testing to terrestrial arthropods and one of them was identified as a key study.

 

In the key study (2014), the chronic toxicity of test substance to collembola (Folsomia candida) was investigated after 28 -day exposure according to OECD 232 (1999) guideline. The test item was incorporated into the soil. Ten female collembolan per replicate were exposed to a concentrations of 141 mg a.i./kg soil dry weight, alongside with a control. The reproduction NOEC was determined to be ≥ 141 mg a.i./kg soil d.w.

 

In a supportive study (2014), the chronic toxicity of test susbtance to mites (H. aculeifer) was investigated after 14-day exposure according to OECD 226 guideline. The mites were exposed to a concentration of 211 mg a.i./kg soil dry weight, alongside with a control. The NOEC (14-d) was determined to be ≥ 211 mg a.i./kg dry weight soil.

 

Additionally, one study on Apis mellifera was conducted with the substance. The acute LD₅₀ for adult honey bees was > 201 µg a.i./bee for both oral contact exposure.