(1-hydroxyethylidene)bisphosphonic acid, potassium salt

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to Annex 3 of the CSR and IUCLID Section 13 for justification of read-across between members of the HEDP category.

Reason / purpose for cross-reference:

read-across source

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

472.5 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

other: active acid

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 945 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

other: active acid

Basis for effect:

mortality

Duration:

56 d

Dose descriptor:

EC50

Effect conc.:

> 945 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

other: active acid

Basis for effect:

reproduction

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

>= 945 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

other: active acid

Basis for effect:

growth

Remarks:

biomass

Reference 2

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 March 2014 - 15 May 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 222 (Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei))

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

- Method of mixing into soil (if used): A respective test item was weighed out for each test item concentration and solved in demineralised water. The spiking solyutions and additional demineralised water were added to the artificial soil to adjust the humidity of the artificial soil to a moisture of 52% of the maximum water holding capacity. Test medium was thoroughly mixed to ensure homogenous distribution

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: earthworm
- Source: laboratory stock population
- Age at test initiation (mean and range, SD): aged 2-12 months, difference of age did not deviate by more than 1 per month
- Weight at test initiation (mean and range, SD): 0.32 to 0.54 g

ACCLIMATION
- Acclimation period: two days
- Acclimation conditions (same as test or not): same as the test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

56 d

Remarks:

Cocoons and offspring were incubated under the same conditions for further 4 weeks.

Test temperature:

20 ± 2 °C

pH:

6.0 ± 0.5

Moisture:

52% of the maximum water holding capacity

Details on test conditions:

TEST SYSTEM
- Test container (material, size): plastic boxes, inner diameter of 15.0cm corresponding to a bottom surface area of 177cm squared. Lids used were transparent and perforated to enable sufficient gas exchange
- Amount of soil or substrate: approximately 600g
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 8


SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition (if artificial substrate): 10% peat, 20% kaolin, 69% air dried quartz sand, 0.35% calcium carbonate
- Maximum water holding capacity (in % dry weight): 55.8 g / 100g dry weight
- CEC: not reported
- Pretreatment of soil: stored with lid on to prevent the test soil drying out

OTHER TEST CONDITIONS
- Photoperiod: 16 hour light : 8 hour dark
- Light intensity: 400 -800 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality, biomass and reproduction

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

Nominal and measured concentrations:

control - 62.5 – 125 – 250 – 500 – 1000 mg test item/kg soil dry weight

Reference substance (positive control):

yes

Remarks:

Carbendazim

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

472.5 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

other: active acid

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 945 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

other: active acid

Basis for effect:

mortality

Duration:

56 d

Dose descriptor:

EC50

Effect conc.:

> 945 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

other: active acid

Basis for effect:

reproduction

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

>= 945 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

other: active acid

Basis for effect:

growth

Remarks:

biomass

Results with reference substance (positive control):

Significant effects between 1 and 5 mg a.i./kg soil dry weight.

Table 1. Body weight changes of adult earthworms after 28 days' exposure to HEDP-H

Application rates (mg test item / kg soil dry weight)	Mean body weight		Mean body weight change (SD) (%)
	Day 0	Day 28
Control	0.39	0.51	29.2 (5.80)
62.5	0.39	0.50	28.2 (8.63)
125	0.39	0.50	26.9 (4.98)
250	0.39	0.52	32.3 (3.19)
500	0.39	0.50	27.5 (4.72)
1000	0.39	0.49	24.4 (6.43)

Table 2. Adult mortality after 28 days' exposure to HEDP-H.

Application rates (mg test item / kg soil dry weight)	Mean mortality of adult earthworms after 28 days exposure (%)
Control	0
62.5	2.5
125	0
250	0
500	0
1000	2.5

Table 3. Reproduction rate of earthworms after 56 days' exposure to HEDP-H

Application rates (mg test item / kg soil dry weight)	Replicate	Number of juveniles	Mean (SD)	CV (%)	% of control (* significantly reduced compared to control)
Control	1	78	88 (10.8)	12.3	-
	2	94
	3	107
	4	84
	5	76
	6	83
	7	98
	8	82
62.5	1	74	85 (9.43)	11.1	96.6
	2	81
	3	94
	4	92
125	1	110	115 (9.87)	8.58	130
	2	120
	3	126
	4	104
250	1	98	104 (17.3)	16.6	118
	2	125
	3	84
	4	108
500	1	72	82 (8.96)	10.9	93.2
	2	78
	3	93
	4	84
1000	1	52	46 (12.7)	27.5	52.3 *
	2	48
	3	27
	4	55

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this study, HEDP-H did not induce evident mortality, pathological symptoms or changes of the behaviour of adult earthworms after 28 days of exposure in all tested concentrations. The adult earthworm biomass increased in the control and in all application rates without any statistically significant differences. After eight weeks of exposure, the earthworm reproduction was not statistically significantly reduced at the test item concentrations 62.5, 125, 250 and 500 mg test item/kg soil dry weight. However, at 1000 mg test item/kg soil dry weight the reproduction rate was statistically significantly reduced.
The EC50 - value for reproduction was determined to be >1000 mg test item / kg soil dry weight, which is equivalent to > 945 mg active acid/kg soil dry weight.

Thus, the No Observed Effect Concentration (NOEC) for HEDP-H summarizing the endpoints mortality and body weight and reproduction of Eisenia fetida after 8 weeks of exposure in artificial soil was determined to be 500 mg test item/kg soil dry weight, which is equivalent to 472.5 mg active acid/kg soil dry weight.

Executive summary:

Effects of HEDP-H on mortality, biomass and the reproductive potential of the earthworm species Eisenia fetida (Annelida, Lumbricidae) were determined according to the Guidelines DIN ISO 11268-2 (1998), OECD 222 (2004) and BBA (1994). The study was conducted under static conditions over 8 weeks with the test item concentrations 62.5, 125, 250, 500 and 1000 mg test item/kg soil dry weight, which were mixed into artificial soil containing 10 % peat and a control using untreated artificial soil. 80 test organisms were inserted into 8 control replicates and 40 test organisms were divided into 4 replicates for each treatment (10 earthworms per replicate). They had an individual body weight between 0.32 and 0.54 g at experimental starting.

After 28 days of exposure in soil, no evident earthworm mortalities (< 10%) as well as no evident pathological symptoms or changes in the behaviour of adult earthworms were observed in all treatments. Moreover, no statistically significant differences in earthworm body weights were observed at all test item concentrations compared to the control. After further four weeks the reproduction rate (average number of juveniles produced) was 88 in the control and ranged between 46 and 115 in the test item treatment rates. Compared to the control, no statistically significant reduction of reproduction was observed at the test item concentrations 62.5, 125, 250 and 500 mg test item/kg soil dry weight. However, at 1000 mg test item/kg soil dry weight the reproduction was statistically significantly reduced.

Overall when expressed in terms of the active acid content, the NOEC of the test item concerning mortality, biomass and reproduction of earthworms was determined to be 472.5 mg active acid/kg soil dry weight. The EC₅₀ value for reproduction was determined to be > 945 mg active acid/kg soil dry weight.

 

Description of key information

56-day NOEC and EC₅₀ values of 472.5 and >945 mg active acid/kg soil dry weight, reproduction, Eisenia fetida.

Key value for chemical safety assessment

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

472.5 mg/kg soil dw

Additional information

56-day NOEC and EC₅₀ values of 472.5 and >945 mg active acid/kg soil dry weight were determined for the effects of HEDP-H on the reproduction of Eisenia fetida (Noack, 2014). In this study, no effects were observed to mortality and growth, giving NOEC values of ≥945 mg active acid/kg soil dry weight for both endpoints.

Two supporting studies reported 14-day LC₅₀ values of >960 mg active acid/kg soil dry weight and >1000 mg active acid/kg soil dry weight for the effects of HEDP (2-3Na) and HEDP-H on Eisenia fetida (Henkel, 1984 and Springborn Laboratories, 1990, respectively).

The acid, sodium and potassium salts in the HEDP category are freely soluble in water and, therefore, the HEDP anion is fully dissociated from its sodium or potassium cations when in solution. Under any given conditions, the degree of ionisation of the HEDP species is determined by the pH of the solution. At a specific pH, the degree of ionisation is the same regardless of whether the starting material was HEDP-H, HEDP (1-2Na), HEDP (2-3Na), HEDP-4Na, HEDP-xK or another salt of HEDP.

 

Therefore, when a salt of HEDP is introduced into test media or the environment, the following is present (separately):

1. HEDP is present as HEDP-H or one of its ionised forms. The degree of ionisation depends upon the pH of the system and not whether HEDP (1-2Na), HEDP (2-3Na), HEDP-4Na, HEDP-xK salts, HEDP-H or another salt was added.
2. Disassociated sodium/potassium cations. The amount of sodium/potassium present depends on which salt was added.
3. Divalent and trivalent cations have much higher stability constants for binding with HEDP than the sodium or potassium ions, so would preferentially replace them. These ions include calcium (Ca²⁺), magnesium (Mg²⁺) and iron (Fe³⁺). Therefore, the presence of these in the environment or in biological fluids or from dietary sources would result in the formation of HEDP-dication (e.g. HEDP-Ca, HEDP-Mg) and HEDP-trication (e.g. HEDP-Fe) complexes in solution, irrespective of the starting substance/test material.

In this context, for the purpose of this assessment, read-across of data within the HEDP Category is considered to be valid.