2-phosphonobutane-1,2,4-tricarboxylic acid

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-07-20 until 1994-08-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

Deviations:

no

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

NA

Vehicle:

yes

Details on preparation and application of test substrate:

The substrate (69% fine quartz sand, 10% peat, 20% kaolin, around 1% calcium carbonate) was first mixed dry in a plough-share mixer, and moistened with some of the final volume of water required. For the study, 2.5 g of the test substance were added to 500 mL deionized water and stirred on a magnetic stirrer for 30 min. The concentrations for the study were prepared by mixing equivalent parts of this stock solutions into the test substrate thoroughly with a domestic mixer. At the same time the rest of the deionised water required was mixed into the test substrate in each test container. It was claimed in the report that it was shown in a separate study, using 14C-labeled ingredients, under GLP-guidelines that the described method gives an homogenous and reproducible distribution of substances in the test substrate. The preparation of the artificial soil with the test substance is in agreement with the OECD 207 guideline.

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Eisenia fetida andrei.
- Source: Prof. Graff, Forschungsanstalt für Landwirtschaft, Braunschweig
- Age at test initiation (mean and range, SD): More than two month old.
- Weight at test initiation (mean and range, SD): A mean weight of 0.38 g.
ACCLIMATION
- Acclimation period: One day prior to the start of the study.
- Acclimation conditions (same as test or not): Same of the test without the test substance.
- Health during acclimation (any mortality observed): NA

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Remarks:

NA

Post exposure observation period:

NA

Test temperature:

20 plus minus 1 °C.

pH:

At the beginning of the study the measured pH was 6.37 and 6.43. At the end of the study the pH value was 6.44.
It is indicated in study that it was shown in a separate study that the pH of the treated substrate (Bayhibit AM in freshly prepared soil) was not significantly different to control substrate.

Moisture:

Water content of the substrate (%) was 26.0 at the start of the study and 32.9 and 32.7 at the end of the study.
Water content as % of the maximum water capacity was 64.1 and 63.0 at the start of the study. When the test substance was added, 100 mL deionised water was also added to each test container so that the water content in the test substrate was around 35% when the worms were introduced.

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 1.5 litre preserving jars, covered with glass lids.
- Amount of soil or substrate: 500 g dry weight (equivalent to 775g wet weight) was prepared for each test container.
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 4
- No. of replicates per vehicle control: The vehicle is water and therefore vehicle control is the negative control. No additional 4 replicates vehicle control were needed.
SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
its an artificial soil- 69% fine quartz sand, 10% dried finely ground peat, 20% kaolin, around 1% calcium carbonate.
OTHER TEST CONDITIONS
- Photoperiod: Constant light
- Light intensity: NA
EFFECT PARAMETERS MEASURED (with observation intervals if applicable): The number of surviving earthworms was counted 7 days after the start of the study. After 14 days, the weight and the number of surviving earthworms were determined.
VEHICLE CONTROL PERFORMED: See above (No. of replicates per control)
TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Range finding study
- Test concentrations: NA
- Results used to determine the conditions for the definitive study: NA

Nominal and measured concentrations:

Nominal concentrations.: 1, 10, 100, 1000 mg/kg of the aqueous solution of PBTC in dry weight substrate (artificial soil consisting of sand, clay mineral and peat)

Reference substance (positive control):

no

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 397 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Mortality, weight changes, abnormalities like changes in the behaviour.

Remarks on result:

other: The test item was employed as a 39.7% aquoeus solution of PBTC. Based on the purity of the anhydrous substance the effect value of >1000 mg/kg soil dw corresponds to 397 mg/kg soil dw PBTC

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

397 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Mortality, weight changes, abnormalities like changes in the behaviour.

Remarks on result:

other: The test item was employed as a 39.7% aquoeus solution of PBTC. Based on the purity of the anhydrous substance the effect value of >1000 mg/kg soil dw corresponds to 397 mg/kg soil dw PBTC

Duration:

14 d

Dose descriptor:

LOEC

Effect conc.:

> 397 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Mortality, weight changes, abnormalities like changes in the behaviour.

Remarks on result:

other: LOEC = LLC The test item was employed as a 39.7% aquoeus solution of PBTC. Based on the purity of the anhydrous substance the effect value of >1000 mg/kg soil dw corresponds to 397 mg/kg soil dw PBTC

Details on results:

- Mortality at end of exposure period: No
- Total mass of adults at beginning of test: NA
- Changes in body weight of live adults (% of initial weight) at end of exposure period: Not significant

- Morphological abnormalities: No
- Behavioural abnormalities: No

Results with reference substance (positive control):

NA

Reported statistics and error estimates:

The weight results of the control and the test concentrations were analysed by U-test and were found not to differ significantly (P=0.05).

No remarks.

Validity criteria fulfilled:

yes

Conclusions:

The test item was employed as a 39.7% aquoeus solution of PBTC. Based on the purity of the anhydrous substance the effect value of >1000 mg/kg soil dw for the aqueous solution corresponds to 397 mg/kg soil dw for the active ingredient PBTC.

Executive summary:

Different concentrations (1 -1000 mg) of the test item (39.7% aqueous solution of PBTC), thoroughly mixed in artificial soil, were tested for toxicity of earthworms. After 14 days of exposure to the test material, no significant difference was observed in mortality rate and in weight in any of the different concentration groups that were examined compare to the control group. In addition, abnormalities, like changes in behaviour were also not observed in the study. Thereby, the LC50 (14 days) was determined for Bayhibit AM as > 1000 mg/kg dry weight substrate. In relation to weight alteration and symptoms, the no-observed-effect concentration (NOEC) was 1000 mg/kg dry weight substrate, the lowest-observed-effect concentration (LOEC) and the lowest tested concentration with mortality (LLC = LOEC) was > 1000 mg/kg dry weight substrate.

The test item was employed as a 39.7% aquoeus solution of PBTC. Based on the purity of the anhydrous substance the effect values of >1000 mg/kg soil dw correspond to 397 mg/kg soil dw for the active ingredient PBTC.

Description of key information

2-Phosphonobutane-1,2,4-tricarboxylic acid, was tested for toxicity of earthworms according to OECD Guideline 207. After 14 days of exposure, no significant difference was observed in mortality rate and in weight in any of the different concentration groups that were examined.

The test item was employed as a 39.7% aqueous solution of PBTC. Thus, based on the purity of the anhydrous substance the effect value of >1000 mg/kg soil dw corresponds to 397 mg/kg soil dw for the active ingredient PBTC.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

397 mg/kg soil dw

Long-term EC10, LC10 or NOEC for soil macroorganisms:

397 mg/kg soil dw

Additional information

2-Phosphonobutane-1,2,4-tricarboxylic acid, was tested for toxicity of earthworms according to OECD Guideline 207 as aqueous solution. The test item contains 39.7% of the substance 2-phosphonobutane-1,2,4-tricarboxylic acid. As a worst case the experimental results (EC50 >1000 mg/kg soil dw, NOEC 1000 mg/kg soil dw) of the aqueous solution might be recalculated for the anhydrous form, corresponding in a EC50 >397 mg/kg soil dw and a NOEC of 397 mg/kg soil dw with respect to the purity of the anhydrous substance.

 

The substance falls into Soil Hazard Category 1 (ECHA Guidance R.7c, table R.7.11-2). Risk to soil organisms exposed to the substance is therfore acceptably assessed based on the PNECsoil calculated using the Equilibrium Partitioning Method, with additional support by a confirmatory short-term terrestrial toxicity study. The worst-case derivation from the study results in a PNECsoil of 0.397 mg/kg dwt. The equilibrium method results in the lowest PNECsoil of 0.08856 mg/kg dwt. Therefore, the PNECsoil derived by the Equilibrium Partitioning Method represents a worst-case approach. As the CSA demonstrates PEC/PNEC values of < 1 towards the environment in all cases, no hazard towards the environment is indicated. In conclusion, according to ECHA Guidance R.7c (Figure R.7.11—3 Scheme B: Integrated testing strategy (Annex IX and Annex X substances)) no further testing is required.