Propanamide, 2-hydroxy-N,N-dimethyl-

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2022-09-19 - 2022-10-18

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:

29-07-2016

Qualifier:

according to guideline

Guideline:

ISO 11267 (Inhibition of Reproduction of Collembola by Soil Pollutants)

Version / remarks:

2014

GLP compliance:

yes (incl. QA statement)

Application method:

mixed into soil

Analytical monitoring:

yes

Details on sampling:

Duplicate sample from the homogenous stock solution and two sample of the matrix (deionised water) as control solution were taken. The samples were stored deep frozen (≤-20 °C) until analysis.

Vehicle:

no

Details on preparation and application of test substrate:

- Method of test item application: 27.2 g of the stock solution or of the corresponding dilutions were added to artificial soil equivalent to 250 g dry weight to prepare the target concentrations in the soil. The soil for each treatment group was mixed with a laboratory mixer to ensure a homogeneous distribution. Each group was treated in one batch and then split into the replicates.
- Controls: The control was left untreated and was moistened with deionised water.
-Introduction of test organisms: Collected with an aspirator, put into a small glass tube, counted to ensure that 10 individuals are introduced and placed onto the surface of the treated artificial soil.

Test organisms (species):

Folsomia candida

Animal group:

Collembola (soil-dwelling springtail)

Details on test organisms:

TEST ORGANISM
- Source: laboratory culture
- Age at test initiation: 10-12 days
- Stage at test initiation: juvenile
- Disease free: yes
- Kept according to standard practices: yes

Study type:

laboratory study

Limit test:

no

Total exposure duration:

28 d

Test temperature:

18 - 22 °C

pH (if soil or dung study):

Determined according to ISO 10390 (CaCl2) at test start and test end.
Test start: 5.9 - 6.0
Test end: 5.7 - 5.9

Humidity:

Determined according to ISO 11465 at test start and test end.
Test start: 17.8% to 18.0% (52.3% to 52.8% of the maximum water holding capacity)
Test end: 15.4% to 16.8% (45.4% to 49.5% of the maximum water holding capacity)

Photoperiod and lighting:

Photoperiod: 16h light / 8h dark;
Light intensity: 400 - 800 lux

Details on test conditions:

TEST SYSTEM
- Test container: 100 mL glass containers (diameter: 5 cm), closed tightly to avoid water evaporation
- Amount of artificial soil: 30g (+/- 1.0 g); heigt of soil layer in containers was 2-3 cm
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4; one additional container per treatment to check pH and water content of the test substrate after 28 days
- No. of replicates per control: 8; one additional container per treatment to check pH and water content of the test substrate after 28 days
- Feeding: 2 mg granulated dry yeast for each test vessel at the beginning of the test and after 15 days

Composition of artificial soil: according to OECD 232:
5% sphagnum-peat, air-dried and finely ground (<2 mm, with no visible plant remains);
20% kaolin clay (kaolinite content >30%);
74.8% fine quartz-sand (F34); more than 50% by mass of particle size 0.05 mm to 0.2 mm;
0.2% calcium carbonate (CaCO3) extra pure was added to adjust pH to 6.0±0.5.
- Maximum water holding capacity: 34% of the dry weight
- Pretreatment of soil or dung: The artificial soil was moistened to approximately half of the final water content 3 days before the application. The additional water required to achieve the final water content was added when applying the test item
- Stability and homogeneity of test material in the medium: Water content was checked on day 15 after the application by reweighing the additional test containers. It was not necessary to compensate for loss of water as the deviation did not exceed 2% of the initial water content.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
mortality: no. of living adults at day 28 after application; missing collembolans were recorded as dead as it was assumed that they had died and degraded during the test period
behaviour: surviving organisms were observed for any abnormal behaviour or conditions at day 28 after application
reproduction: number of juvenile collembolans at day 28 after application

Nominal and measured concentrations:

Nominal: 9.80, 17.6, 31.8, 57.2, 103, 185, 333 and 600 mg N,N-dimethyl lactamide/kg soil dry weight

The analytical mean recovery rate of the stock solution for the highest test concentration (stock solution) was 101%. No test item was detected in the control solution.

Reference substance (positive control):

yes

Remarks:

Boric acid

Key result

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

195.6 mg/kg soil dw

95% CI:

145.8 - 234.6

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

457.5 mg/kg soil dw

95% CI:

415.5 - 509.2

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

185 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

103 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

> 600 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 600 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 600 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Mortality:
Mortality was not statistically significantly different compared to the control up to and including the highest test concentration of 600 mg test item/kg soil dry weight (Fisher’s Exact Test, α = 0.05, one-sided greater). Therefore, the NOEC for mortality was determined to be ≥600 mg test item/kg soil dry weight. The LOEC for mortality was estimated to be >600 mg test item/kg soil dry weight. The LC50 of N,N-dimethyl lactamide for Folsomia candida in artificial soil was estimated to be >600 mg test item/kg soil dry weight.

Behaviour:
No abnormal behaviour was observed with the surviving Collembola.

Reproduction:
There were no statistically significant effects on reproduction up to and including the concentration of 103 mg test item/kg soil dry weight (Williams t-test, α = 0.05, one-sided smaller). At the concentration of 185 mg test item/kg soil dry weight and above, reproduction was significantly reduced compared to the control. The NOEC for reproduction was determined to be 103 mg test item/kg soil dry weight and the LOEC for reproduction was determined to be 185 mg test item/kg soil dry weight. The EC10 for Folsomia candida in artificial soil was determined to be 195.6 mg test item/kg soil dry weight (95% confidence limits of 145.8 to 234.6 mg test item/kg soil dry weight). The EC20 was determined to be 267.7 mg test item/kg soil dry weight (95% confidence limits of 220.0 to 304.6 mg test item/kg soil dry weight). The EC50 was determined to be 457.5 mg test item/kg soil dry weight (95% confidence limits of 415.5 to 509.2 mg test item/kg soil dry weight, Logit Analysis).

More details are given in Table 1.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels:
Mortality: NOEC(28d) = 78.1 mg/kg soil dw, LC50(28d) = 159.4 mg/kg soil dw
Reproduction: NOEC(28d) = 30.5 mg/kg soil dw, EC10(28d) = 36.8 mg/kg soil dw, EC20(28d) = 50.5 mg/kg soil dw, EC50(28d) = 81.6 mg/kg soil dw

Reported statistics and error estimates:

Determination of NOEC/LOEC:
Mortality: Fisher's exact, one-sided, greater, α = 0.05
Reproduction: Williams t-test, one-sided, smaller, α = 0.05

Determination of ECx:
Logit Analysis

 

Table 1: mean mortality and reproduction of adult springtails

Test concentration [mg a.i./kg soil dry weight]	Control	9.8	17.6	31.8	57.2	103	185	333	600
Mean mortality of adult collembola at day 28 (%)	3	3	3	5	5	3	5	3	5
Statistical significance according to Fisher's Exact Test, α = 0.05	-	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.
Mean no. of juveniles at day 28	832	868	796	851	806	777	717	624	252
Reproduction in % of control at day 28	-	104	96	102	97	93	86	75	30
Statistical significance, Williams t-test, α = 0.05	-	n.s.	n.s.	n.s.	n.s.	n.s.	*	*	*

n.s. not significantly different compared to control

* significantly different compared to the control

 

 

pH and water content of artifical soil

treatment group	pH		% water content		% WHC (% maximum water holding capacity)
	start	at day 28	start	at day 28	start	at day 28
control	6.0	5.9	18.0	16.1	52.8	47.4
9.8	6.0	5.9	17.8	16.6	52.3	48.8
17.6	6.0	5.8	18.0	15.6	52.8	45.9
31.8	6.0	5.8	17.9	15.4	52.6	45.4
57.2	6.0	5.8	17.9	16.8	52.7	49.5
103	5.9	5.8	17.9	15.8	52.7	46.5
185	5.9	5.8	17.9	16.3	52.6	47.9
333	5.9	5.7	17.9	16.8	52.7	49.5
600	5.9	5.7	17.9	16.3	52.6	47.9

 

Validity criteria fulfilled:

yes

Remarks:

Mean control mortality: 3% (≤20%); Control reproduction: The number of juvenile Collembola per replicate was 711 to 928 (≥ 100); Coefficient of variation of the control reproduction: 10.5% (<30%)

Executive summary:

In a chronic toxicity study, the effects of 2-hydroxy-N,N-dimethylpropanamide on Folsomia candida were investigated. Juvenile Collembola were exposed for 28 days at concentrations of 9.80, 17.6, 31.8, 57.2, 103, 185, 333 and 600 mg test item/kg soil dry weight and a control, in groups of 10 animals with 4 replicates for the test item treatments and 8 replicates for the control. The test item was incorporated into artificial soil with a content of 5% peat. After 28 days, assessment of adult mortality, behavioural effects and reproduction was performed.

Mortality of the Collembola exposed to the test item (3% - 5%) was not statistically significantly different from the control mortality (3%) up to and including the highest test concentration of 600 mg test item/kg soil dry weight. Thus, the NOEC for 2-hydroxy-N,N-dimethylpropanamide based on mortality was determined to be ≥600 mg test item/kg soil dry weight. The LC50 was estimated to be >600 mg test item/kg soil dry weight.

The mean number of juveniles counted 28 days after introduction of the parental Collembola into the test vessels was 832 in the control and 868, 796, 851, 806, 777, 717, 624 and 252 at the test concentrations of 9.80, 17.6, 31.8, 57.2, 103, 185, 333 and 600 mg test item/kg soil dry weight, respectively. Reproduction of the Collembola exposed to 2-hydroxy-N,N-dimethylpropanamide was not statistically significantly different compared to the control up to and including the test concentration of 103 mg test item/kg soil dry weight. At 185 mg test item/kg soil dry weight and above, reproduction was statistically significantly reduced compared to the control.  The NOEC based on reproduction was determined to be 103 mg test item/kg soil dry weight. The EC10 based on reproduction was 195.6 mg test item/kg soil dry weight.

No behavioural abnormalities were observed in any of the treatment groups.

Description of key information

One study of long-term toxicity to terrestrial arthropods conducted according to OECD 232 is available. The 28-day EC10 for reproduction was determined to be 195.6 mg test item/kg soil dw. The corresponding NOEC was 103 mg/kg soil dw.

Key value for chemical safety assessment

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

195.6 mg/kg soil dw