(1-hydroxyethylidene)bisphosphonic acid, potassium salt

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms, other

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Non-quantitative study of effect of increasing concentration of test substance on the sewage treatment process

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

70 d

Remarks on exposure duration:

With stepwise increase of test substance concentration

Reference substance (positive control):

no

Duration:

53 d

Dose descriptor:

NOEC

Effect conc.:

300 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

other: MBAS reduction

Duration:

54 d

Dose descriptor:

LOEC

Effect conc.:

400 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

other: MBAS reduction

Details on results:

A artifical sewage treatment plant was continuously fed with nutrient and anionic surfactant plus increasing concentrations of HEDP. Up to a concentration of 300 mg/l the MBAS reduction (methylene blue substance - analytical parameter for anionic surfactants) was not impaired. After increase of HEDP concentration to 400 mg/L the MBAS reduction was reduced but recovered within 5 days. The MBAS reduction was reduced again after an increase of the HEDP concentration in the inflow to 600 mg/l.

Conclusions:

A non-standard study of effects on aerobic sewage treatment process micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The result of a lack of effects on respiration up to 300 mg/L provides reliable evidence.

Reference 2

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Remarks:

It was not compliant with GLP.

Qualifier:

equivalent or similar to guideline

Guideline:

DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)

Version / remarks:

Test uses P phosphoreum. Also cites draft DIN Leuchtbakterientest.

Principles of method if other than guideline:

Short term test using luminosity of P phosphoreum as an indicator of inhibition. Test using microtox reactor

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Photobacterium phosphoreum

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Reference substance (positive control):

no

Duration:

30 min

Dose descriptor:

IC0

Effect conc.:

> 250 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: luminescence

Remarks on result:

other: IC0 estimates derived from tests conducted at 3 concentrations

Conclusions:

A reliable IC0 value of >250 mg/l has been determined for the effects of HEDP-xNa on the bioluminescence of the bacterium Photobacterium phosphoreum.

Reference 3

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

Non-quantitative study of effect of increasing concentration of test substance on the sewage treatment process

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge

Test type:

not specified

Water media type:

not specified

Limit test:

no

Total exposure duration:

30 d

Reference substance (positive control):

no

Duration:

30 d

Dose descriptor:

NOEC

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

other: sewage gas production volume

Duration:

30 d

Dose descriptor:

LOEC

Effect conc.:

500 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

other: sewage gas volume reduced and fermentation delayed

Details on results:

At 50 mg/L HEDP showed no effects.
At 100 and 200 mg/L the start of fermentation was delayed, but constant gas volume was achieved in the same period as in the control.
At 500 mg/L HEDP, the system was strongly disturbed, as indicated by a late beginning of fermentation, and greatly reduced sewage gas production volume.

Conclusions:

A non-standard study of effects on sewage treatment plant micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The result of a lack of effects on respiration up to 200 mg/L provides reliable evidence.

Reference 4

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The full report was not available.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

DIN 38412

GLP compliance:

no

Analytical monitoring:

no

Test organisms (species):

Pseudomonas putida

Details on test conditions:

Type: aquatic

Duration:

30 min

Dose descriptor:

EC0

Effect conc.:

960 mg/L

Result expressed as nominal concentration. Properties of the
test substance and evidence from other studies (where
concentrations were measured) indicate that nominal and
measured concentrations are likely to be in good agreement.

Reference 5

Endpoint:

toxicity to microorganisms, other

Type of information:

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

Adequacy of study:

weight of evidence

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

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Duration:

30 d

Dose descriptor:

NOEC

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

other: sewage gas production volume

Remarks on result:

other: Henkel, 1972a

Duration:

53 d

Dose descriptor:

NOEC

Effect conc.:

300 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

other: MBAS reduction

Remarks on result:

other: Henkel, 1972b

Duration:

30 min

Dose descriptor:

IC0

Effect conc.:

> 250 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: luminescence

Remarks on result:

other: IC0 estimates derived from tests conducted at 3 concentrations

Remarks:

Grohmann and Horstmann, 1989

Duration:

30 min

Dose descriptor:

EC0

Effect conc.:

960 mg/L

Remarks on result:

other: Henkel, 1982

Description of key information

The available data provide a general weight of evidence of a lack of inhibition of aerobic and anaerobic WWTP micro-organisms at concentrations up to ca. 200 mg active acid/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

200 mg/L

Additional information

A respiration inhibition test with HEDH (2-3Na) and aerobic bacteria Pseudomonas putida following the test guideline DIN 38412 part 27 showed the result EC₀ = 960 mg test material/L within a contact time of 30 minutes (Henkel, 1982). However full details are not available and the study is assigned reliability 4. The general test principle was comparable to the OECD 209 method. (Henkel unpublished data, pers. comm.)

A non-standard reliable study of effects of HEDP-H on anaerobic sewage treatment plant micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The result of a lack of effects on bio-gas production up to at least 200 mg active acid/L after 11 days exposure in a simulation study provides reliable evidence (Henkel, 1972a).

A non-standard reliable study of effects of HEDP-H on aerobic sewage treatment plant micro-organisms was conducted according to generally accepted scientific principles but lacks detail in the study report. The result of a lack of effects on MBAS reduction up to 300 mg active acid/L after 53 days exposure in a simulation study provides reliable evidence (Henkel, 1972b).

A reliable EC₀ value of >250 mg test material/L has been determined for the effects of HEDP (2-3Na) on the bioluminescence of the freshwater bacterium Photobacterium phosphoreum (Grohmann and Horstmann, 1989).

These studies have been used as weight of evidence to demonstrate the low toxicity of HEDP and its salts to micro-organisms.

Other data of non-assignable reliability have determined the low toxicity of HEDP and its salts towards anaerobic sludge micro-organisms (Steber and Wierich, 1986) and Pseudomonas putida (Schoberl and Huber, 1988).

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.