Poly(oxy-1,2-ethanediyl), α-[2-(dide- cylmethylammonio)ethyl]- .omega.- hydroxy-, propanoate (salt) (Bardap 26)

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13/07/2000 - 24/10/2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Deviations:

yes

Remarks:

Low humic soils biomass under 1% total organic carbon

Qualifier:

according to guideline

Guideline:

OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Specific details on test material used for the study:

No information provided.

Analytical monitoring:

no

Details on sampling:

Samples were taken to determine nitrogen metabolite content on days 5 and 28. CO2 evolution was determined on days 5 – 8 and 25 – 28.

Vehicle:

not specified

Details on preparation and application of test substrate:

Two soils were used in this study, a sandy loam soil, and a low humic content sand soil.
A sample of sandy loam soil was taken from grassland located at the Maasdijk, Heerewaarden, The Netherlands on 30 June 2000. A sample of low humic content sand soil was taken at the Bulb Research Institute, Lisse, The Netherlands on 30 June 2000. The soil samples were stored at refrigerator temperatures pending use. Soil was dried and sieved prior to testing to obtain soil granules < 2mm.
Powdered lucerne meal was added (C/N ratio 13/1) was added at a concentration of 0.3 g per 50 g dry weight and mixed thoroughly.

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

20 ± 2°C

Moisture:

Approximately 50% of Maximum Water Holding Capacity (MWHC)

Details on test conditions:

50 ± 0.5 g dry weight of soil samples were mixed with lucerne meal and placed in 100 ml Scott Duran bottles. The samples were incubated in the dark at 20 ± 2°C. A stock solution of the test substance was created and subsequent dilutions were made in ultrapure water, 0.5 ml of which was added to the 50g dry weight soil sample to achieve a final test substance concentration. Samples were dosed with test substance at concentrations 0, 10, 100 and 1000 mg a.s./kg dry weight of soil.
At the start of the test and after 5 and 28 days, nitrite, nitrate and ammonium were extracted from the soils and were analyzed with Dr Lange test kits. Measurements were carried out using a CADAS 30 spectrophotometer.
Carbon mineralization was measured at 5 and 28 days by trapping evolved CO2 in a 0.6M sodium hydroxide solution for 72 hours and titrating it.

Nominal and measured concentrations:

0, 10, 100 and 1000 mg/kg dry weight of soil

Reference substance (positive control):

not specified

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Remarks on result:

other:

Remarks:

Sandy loam low humic content sand

Details on results:

The test substance had no effect on the production of nitrates, nitrites and carbon dioxide. The rate of ammonium production increased. The results indicate tat the test substance did not inhibit the nitrate and nitrite formation at the tested concentrations in both soil types tested after 5 and after 28 days of incubation. No significant relevant reduction effects were found between the CO2 evolution rates in treated and untreated soils. An increase in CO2 evolution in several samples may be partly caused by the biodegradable solvent in the test substance.

Results with reference substance (positive control):

No information provided.

Reported statistics and error estimates:

Two-tailed Dunnett’s test

Table 1. Nitrite formation

Dose concentration (mg/g)	Mean nitrite formation rate (mg/kg dry weight/day)				% reduction
	Low humic content sand		Sandy loam		Low humic content sand		Sandy loam
Day	5	28	5	28	5	28	5	28
0	0.35	0.02	0.80	0.02	-	-	-	-
10	0.38	0.02	0.81	0.01	-8.1	6.7	-1.2	10.7
100	0.34	0.02	0.81	0.02	4.5	4.1	-1.4	0.8
1,000	0.35	0.06	0.79	0.02	0.6	-135.4	0.8	-9.3

 

Table 2. Ammonium formation

Dose concentration (mg/g)	Mean ammonium formation rate (mg/kg dry weight/day)				% reduction
	Low humic content sand		Sandy loam		Low humic content sand		Sandy loam
Day	5	28	5	28	5	28	5	28
0	2.36	0.29	1.66	0.10	-	-	-	-
1,000	4.33	0.40	3.09	0.10	-83.8	-86.5	-39.1	-6.2

 

Table 3. Carbon dioxide production

Dose concentration (mg/g)	Mean carbon dioxide formation rate (mg/kg dry weight/day)				% reduction
	Low humic content sand		Sandy loam		Low humic content sand		Sandy loam
Day	5-8	25-28	5-8	25-28	5-8	25-28	5-8	25-28
0	284.0	28.6	237.9	25.7	-	-	-	-
10	327.3	25.3	216.3	31.2	-15.2	11.6	9.1	-21.5
100	292.3	8.7	260.4	31.3	-2.9	69.6	-9.5	-22.0
1,000	261.9	104.3	181.6	31.4	7.8	-264.8	23.6	-22.3

Validity criteria fulfilled:

yes

Conclusions:

The difference in CO2 prodction and nitrogen transformation between the treated and untreated soil samples did not exceed 50% after 28 days of incubation. The highest inhibition recorded was 82.5% inhibition of nitrification in the sandy loam soil after 5 days at 10 mg/kg. However, after 28 days of incubation the inhibition was below 25%. Therefore it was not necessary to continue the test beyond 28 days.
Didecyldimethylammonium Chloride can be characterised as having no long-term influence on nitrogen or carbon transformations in soils under the conditions of this study.

Executive summary:

In a study conducted in accordance with OECD Guidelines 216 and 217, 50 g samples of low humic content sand and sandy loam were treated with Didecyldimethylammonium Chloride at concentrations of 0, 10, 100 and 1000 mg/kg dry weight soil and incubated in the dark at 20°C for 28 days. Samples were taken to determine nitrogen metabolite content on days 5 and 28. CO₂ evolution was determined on days 5 – 8 and 25 – 28. Didecyldimethylammonium Chloride can be characterised as having no long-term influence on nitrogen or carbon transformations in soils. The test substance had no significant effect on the production of nitrates, nitrites and carbon dioxide.

Description of key information

One key study is available. The study was conducted in accordance with OECD Guidelines 216 and 217, with no deviations and was GLP compliant. Sandy loam and low humic content sand were treated with the test material Bardac 22 at concentrations of 0, 10, 100 and 1000mg/kg dry weight soil for 28 days to assess the toxicity to soil microorganisms. Didecyldimethylammonium Chloride can be characterised as having no long-term influence on nitrogen or carbon transformations in soils. The test substance had no significant effect on the production of nitrates, nitrites and carbon dioxide.

The EC50 is greater 1000 mg/kg dw, result based on nominal concentration.

Key value for chemical safety assessment

Short-term EC50 for soil microorganisms:

1 000 mg/kg soil dw

Additional information

In a study conducted in accordance with OECD Guidelines 216 and 217, 50 g samples of low humic content sand and sandy loam were treated with Didecyldimethylammonium Chloride (DDAC) at concentrations of 0, 10, 100 and 1000 mg/kg dw soil and incubated in the dark at 20°C for 28 days. Samples were taken to determine nitrogen metabolite content on days 5 and 28. CO₂evolution was determined on days 5 – 8 and 25 – 28. Didecyldimethylammonium Chloride can be characterised as having no long-term influence on nitrogen or carbon transformations in soils. The test substance had no significant effect on the production of nitrates, nitrites and carbon dioxide.

It should be noted that the conversion of organic nitrogen to inorganic nitrogen is a three-step sequential process which involves a wide range of microorganisms including fungi, heterotrophic bacteria and autotrophic bacteria. The results of this study indicate that all these groups remain present and functional when exposed to DDAC. The EC50 is greater 1000 mg/kg dw, result based on nominal concentration.

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