Didecyldimethylammonium chloride

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From November 17, 2003 to March. 4, 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Three additional replicate units were prepared for each the lowest and the highest treatment concentrations, for the natural soil, and for the quartz sand. They served for the extraction of DDAC on the day the seeds were placed.
- Sample storage conditions before analysis: Samples were maintained under the same test conditions as the planted units throughout the test period.

Vehicle:

not specified

Details on preparation and application of test substrate:

No data

Species:

Triticum aestivum

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

-family: Gramineae (Poceae); common name: wheat; source: Agro biologically produced seeds ‘Blé tendre à germer’, Celnat, batch n° 3 273120 010304, expiry date 13/09/2004 (43700 Saint-Germain-Laprade, France)

Species:

Sinapis alba

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

-family: Cruciferae (Brassicaceae); common name: Mustard; source: Agro-biologically produced seeds ‘White mustard’, Le Biau Germe, batch 2001,
expiry date : 12/2004 (47360 Montpezat d’Agenais, France)

Species:

Trifolium pratense

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

-family: Leguminosae (Fabaceae); common name red clover; source: Agro-biologically produced seeds ‘Trèfle violet’. Le Biau Germe, batch CB1,
expiry date : 12/2006 (47360 Montpezat d’Agenais, France) (Final test only)

Test type:

other: Seedling emergence and growth

Study type:

laboratory study

Substrate type:

other: Natural soil & Quartz sand

Limit test:

yes

Total exposure duration:

14 d

Remarks:

14 d after 50 % of the control plants had emerged

Post exposure observation period:

No data

Test temperature:

No data

pH:

6.7

Moisture:

38.3 % dry soil

Details on test conditions:

Test type: growth chamber test
Container type: 0.5 L capacity plastic pots
Seed germination potential: No information
Number of replicates: 4
Numbers of plants per replicate per dose: 40
Date of planting: on natural soil: January 23, 2004
on sand: February 13, 2004
Plant density: 10 plants in 250 g soil
Date of test substance application: The substance was added to the natural soil 3 d before the start of the test and to sand 1 d before the start.
High of plants at application: Seeds were planted after application
Date of phytotoxicity rating or harvest: on natural soil: February 13, 2004
on sand: March 1, 2004
Dates of analysis: Immediately after the end of the test

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location:
- Pesticide use history at the collection site:
- Collection procedures:
- Sampling depth (cm):
- Soil texture (if natural soil)
- % sand: 48.2
- % lime: 42.8
- % clay: 9.0
- Soil taxonomic classification:
- Soil classification system:
- Composition (if artificial substrate):
- Organic carbon (%):
- Maximum water holding capacity (in % dry weigth):
- CEC:
- Pretreatment of soil:
- Storage (condition, duration):

Nominal and measured concentrations:

Concentrations:
- Natural soil: 0, 477.2, 857.1, 1544.1, 2779.8 and 5001.3 mg a.i/kg
- Sand: 0, 30.7, 52.6, 99.7, 167.6 and 301.0 mg a.i./kg

Reference substance (positive control):

no

Key result

Species:

Triticum aestivum

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 5 001.3 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

seedling emergence

Remarks on result:

other: Natural soil

Remarks:

NOEC: >5001.3 mg/kg soil dw act. ingr. (nominal)

Key result

Species:

Sinapis alba

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 5 001.3 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

seedling emergence

Remarks on result:

other: Natural soil

Remarks:

NOEC: 2779.8 mg/kg soil dw act. ingr. (nominal)

Key result

Species:

Trifolium pratense

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 3 891 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

seedling emergence

Remarks on result:

other: Natural soil

Remarks:

NOEC: 857.1 mg/kg soil dw act. ingr. (nominal)

Key result

Species:

Triticum aestivum

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

ca. 1 172 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Remarks on result:

other: Natural soil

Key result

Species:

Sinapis alba

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

ca. 346 mg/kg soil ww

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Remarks on result:

other: Natural soil

Key result

Species:

Trifolium pratense

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

ca. 148 mg/kg soil ww

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Remarks on result:

other: Natural soil

Key result

Species:

Triticum aestivum

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 235 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

seedling emergence

Remarks on result:

other: Quartz sand

Remarks:

NOEC: 167.6 mg/kg soil dw act. ingr. (nominal)

Key result

Species:

Sinapis alba

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 209 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

seedling emergence

Remarks on result:

other: Quartz sand

Remarks:

NOEC: 99.7 mg/kg soil dw act. ingr. (nominal)

Key result

Species:

Trifolium pratense

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

ca. 190 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

seedling emergence

Remarks on result:

other: Quartz sand

Remarks:

NOEC: 99.7 mg/kg soil dw act. ingr. (nominal)

Key result

Species:

Triticum aestivum

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

ca. 68 mg/kg soil ww

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Remarks on result:

other: Quartz sand

Key result

Species:

Sinapis alba

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

ca. 32 mg/kg soil ww

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Remarks on result:

other: Quartz sand

Key result

Species:

Trifolium pratense

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

ca. 11 mg/kg soil ww

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Remarks on result:

other: Quartz sand

Details on results:

Please refer to the 'any other information on results incl. tables' section for details

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

- F test for the % emergence in each treatment.
- Regression curve was calculated using Excel.xls matrical calculation so that the EC50 and its 95 % CI were calculated

At higher concentrations the plants were smaller, but healthy. They seemed to resist lack of water better than the control. The side-effects of test material exhibited great deviation between quartz sand and natural soil. The extraction of test material proved that the natural soil had a strong  sorbing  effect, and the total  recovery of DDAC was not achieved even when acidified methanol was used. That was not the  case  with quartz sand, and this was taken as the source of the differences: the availability of DDAC for the plants differed, depending on the nature of the soil substrate, and DDAC was proved to be less harmful to plant growth under a realistic way of exposure (test on natural soil) than when a chemically inert material as quart sand was used as substrate.

Results: (based on Active ingredient)

Natural soil:
               LC50       EC50       EC50 
            emergence  wet weight dry weight
             [mg/kg]    [mg/kg]    [mg/kg]
___________________________________________
T. aestivum   >5001      1172       3523
S. alba        >5001       346        562
T. pratense    3891       148        488
The most sensitive is T. pratense with EC50 = 148 mg/kg soil wet weight.

Quartz Sand:
              LC50       EC50       EC50 
            emergence  wet weight dry weight
             [mg/kg]    [mg/kg]    [mg/kg]
___________________________________________
T. aestivum    235         68        135
S. alba         209         32        166
T. pratense    190         11        106

Conclusion:The effects of DDAC exhibited great deviation between sand and natural soil. In sand toxic effects take place at lower concentrations than in soil, this is probably due to the lower bioavailability of DDAC in soil caused by stronger adsorption.

Please refer to the attachement for further details on results and the analytics.

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, red clover was identified to be the most sensitive species with 14-day LC50 and NOEC values based on effects on seedling emergence were determined at 3891 and 857.1 mg a.i./kg soil dw respectively, while the 14-day EC50 based on effect on growth (wet weight changes) was determined at 148 mg a.i./kg dw soil.

Executive summary:

A study was conducted to determine the acute toxicity of the test substance, DDAC (40.5% active) on terrestrial plant growth, according to OECD Guideline 208, in compliance with GLP. The study aimed to determine LC50 of the test substance based of emergence and an EC50 based on early stage of growth of variety of terrestrial plants after a single application. The test substance was added only once. The treatment was applied into soil fraction that served for the germination and further development of three distinct plant species: mustard (Sinapis alba), wheat (Triticum aestivum) and red clover (Trifolium pratense).The whole test was duplicated using pure quartz sand and natural soil. Final test conducted following range finding study. Four replicate units (10 seeds/unit) were performed for each of the five test concentrations, so as to encircle both the LC50 and EC50. The nominal concentrations used in the study were as follows: (a) Natural soil: 0, 477.2, 857.1, 1544.1, 2779.8 and 5001.3 mg a.i/kg (b) Sand: 0, 30.7, 52.6, 99.7, 167.6 and 301.0 mg a.i /kg. In the natural soil, the respective LC50 for emergence, EC50 for growth based on wet weight and dry weight changes compared to the control were as (as follows: (a) wheat: >5001, 1172 and 3523 mg a.i./kg (b) mustard: >5001, 346 and 562 mg a.i./kg (c) red clover: 3891, 148 and 488 mg a.i./kg. In the quartz sand, the respective LC50 for emergence, EC50 for growth based on wet weight and dry weight changes compared to the controls were as (as follows: (a) wheat: 235, 68 and 135 mg a.i./kg (b) mustard: 209, 32 and 166 mg a.i./kg (c) red clover: 190, 11 and 106 mg a.i./kg. The corresponding NOEC values based on effect on seedling emergence were determined to be >5001.3, 2779.8, 857.1 mg a.i./kg dw in natural soil and 167.6, 99.7 and 99.7 mg a.i./kg dw in sand. The effects of the test substance exhibited great deviation between sand and natural soil. In sand toxic effects take place at lower concentrations than in soil, this is probably due to the lower bioavailability in soil caused by stronger adsorption. Further, as the toxicity to terrestrial plants in sand is not representative of the natural environment, the EC50 in natural soil was considered as a reasonable worst case for representing toxicity terrestrial plant species. Under the conditions of the study, based on effect on emergence and growth, red clover was identified to be the most sensitive species with lower NOEC and L(E)C50 values. The 14-day LC50 and NOEC values based on effects on seedling emergence were determined at 3891 and 857.1 mg a.i./kg soil dw respectively, while the 14-day EC50 based on effect on growth (wet weight changes) was determined at 148 mg a.i./kg dw soil (Servajena, 2004).  

Description of key information

Based on the study results, red clover was identified to be the most sensitive species. The 14-day NOEC and EC50 values based on seedling emergence and growth were determined at 857.1 and 148 mg a.i./kg soil dw respectively.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

148 mg/kg soil dw

Long-term EC10, LC10 or NOEC for terrestrial plants:

857 mg/kg soil dw

Additional information

A study was conducted to determine the acute toxicity of the test substance, DDAC (40.5% active) on terrestrial plant growth, according to OECD Guideline 208, in compliance with GLP. The study aimed to determine LC50 of the test substance based of emergence and an EC50 based on early stage of growth of variety of terrestrial plants after a single application. The test substance was added only once. The treatment was applied into soil fraction that served for the germination and further development of three distinct plant species: mustard (Sinapis alba), wheat (Triticum aestivum) and red clover (Trifolium pratense).The whole test was duplicated using pure quartz sand and natural soil. Final test conducted following range finding study. Four replicate units (10 seeds/unit) were performed for each of the five test concentrations, so as to encircle both the LC50 and EC50. The nominal concentrations used in the study were as follows: (a) Natural soil: 0, 477.2, 857.1, 1544.1, 2779.8 and 5001.3 mg a.i/kg (b) Sand: 0, 30.7, 52.6, 99.7, 167.6 and 301.0 mg a.i /kg. In the natural soil, the respective LC50 for emergence, EC50 for growth based on wet weight and dry weight changes compared to the control were as (as follows: (a) wheat: >5001, 1172 and 3523 mg a.i./kg (b) mustard: >5001, 346 and 562 mg a.i./kg (c) red clover: 3891, 148 and 488 mg a.i./kg. In the quartz sand, the respective LC50 for emergence, EC50 for growth based on wet weight and dry weight changes compared to the controls were as (as follows: (a) wheat: 235, 68 and 135 mg a.i./kg (b) mustard: 209, 32 and 166 mg a.i./kg (c) red clover: 190, 11 and 106 mg a.i./kg. The corresponding NOEC values based on effect on seedling emergence were determined to be >5001.3, 2779.8, 857.1 mg a.i./kg dw in natural soil and 167.6, 99.7 and 99.7 mg a.i./kg dw in sand. The effects of the test substance exhibited great deviation between sand and natural soil. In sand toxic effects take place at lower concentrations than in soil, this is probably due to the lower bioavailability in soil caused by stronger adsorption. Further, as the toxicity to terrestrial plants in sand is not representative of the natural environment, the EC50 in natural soil was considered as a reasonable worst case for representing toxicity terrestrial plant species. Under the conditions of the study, based on effect on emergence and growth, red clover was identified to be the most sensitive species with lower NOEC and L(E)C50 values. The 14-day LC50 and NOEC values based on effects on seedling emergence were determined at 3891 and 857.1 mg a.i./kg soil dw respectively, while the 14-day EC50 based on effect on growth (wet weight changes) was determined at 148 mg a.i./kg dw soil (Servajena, 2004).  

 

Further, the DDAC biocides assessment report for Product Type 8 conducted under Directive 98/8/EC (evaluating Competent Authority: Italy, June 2015, attached in Section 13 of the IUCLID dataset), reported an additional study on DDAC, apart from the above EQC study (Servajena, 2004). This study was conducted with mustard (Brassica alba), mung bean (Phaseolus aureus) and wheat (Triticum aestivum) in garden soil, where the lowest EC50 = 283 mg a.s./kg dw was calculated for mustard. The RMS further stated that:“The great deviation in the effects recorded in sand and natural soil can be attributed to the lower bioavailability of DDAC in natural soil caused by stronger adsorption to the soil particles as consequence of several binding processes. The results obtained in test with silica sand are considered unrealistic worst case, then only data from the tests conducted with natural soils are taken into account (this approach was agreed at TMII2013); among these, the most sensitive species was T. pratense, with an EC50 = 148 mg/kg soil dw (EQC), which is the endpoint to be taken into account.”  

Therefore, as a conservative approach and following the same approach as the biocides assessment report, the EC50 of 148 mg/kg dw soil based on the effects on growth in red clover, has been considered further for hazard/risk assessment. Further, as per the ECHA R.7c guidance (2017), the updated OECD Guideline 208 (v.2006) although does not cover chronic effects or effects on reproduction, however it is assumed to cover a sensitive stage in the life-cycle of a plant. Considering that the Servajena, 2004 study includes the evaluation of effects on seedling emergence, the 14-day NOEC value of 857 mg/kg dw soil from this study have been used as estimate of chronic toxicity.