Potassium salts of [hexane-1,6-diylbis[nitrilobis(methylene)]]tetrakisphosphonic acid (4-7 K:1)

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: US EPA Methods for acute toxicity tests with fish, macroinvertebrates, and amphibians. EPA 66013-75-009. April 1975.

Deviations:

not specified

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)

- Method: The test substance was diluted to make a stock solution of 100 mg/ml. In a 6 L flask well water and food was mixed. The solution was transferred into 1L volumetric flasks, mixed well, then 200 ml were drawn into the test vessels.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Common name: water flea

- Feeding during test: The daphnids were fed at a concentration of 10 mg/l at each test medium renewal.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

28 d

Nominal and measured concentrations:

Nominal test concentrations: 3.37, 6.75, 12.5 and 25 mg active acid/L.

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Material, size, headspace, fill volume: 250 ml test beakers filled with 200 ml test solution.

- Renewal rate of test solution (frequency): 2 day renewal

- No. of organisms per vessel: 5

- No. of vessels per concentration (replicates): 4

- No. of vessels per control (replicates): 4



TEST MEDIUM / WATER PARAMETERS

- Source of dilution water: Well water


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : survival and reproduction (offspring produced) at every water renewal (ca. 2 days).



RANGE-FINDING STUDY
A Range Finding study is said to have been conducted previous to the test in order to narrow down the range of concentrations in the test, however details were not reported. A short term acute test with Daphnia was also conducted which determined a 48 h EC50 equivalent to 883 mg active acid/L.

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 25 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Remarks:

active acid

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 25 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Remarks:

active acid

Basis for effect:

other: adult survival and reproduction (no. of offspring)

Details on results:

- Mortality of parent animals: see Table 1 for details.

- Time to first brood release or time to hatch: the data reported shows that offspring were produced by day 9 in all treatment groups.

Reported statistics and error estimates:

For chronic data NOECs were determined by comparing means and standard errors in control vs. treated.

Table 1: Effect of ATMP on growth and survival of D. magna after 28 days (average of 4 replicates).

Nominal concentrations (mg a.a./L)	Mortality of parents		Cumulative number of offspring
	No. Alive	% mortality
Control	4.3 ± 1.2	14	143.7
25	4.0 ± 0.8	20	128.3
12.5	4.2 ± 1.5	16	139.5
6.75	4.2 ± 1.0	16	141.6
3.37	4.7 ± 0.5	6	155.4

 

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.

Not enough information is reported on water quality, however the frequency of water renewals suggests the parameters to be in acceptable ranges.

 

Validity criteria fulfilled:

not specified

Conclusions:

A 28 day NOEC value of ≥ 25 mg active acid/L has been determined for the effects of the test substance on reproduction of Daphnia magna.

Description of key information

No study of long-term toxicity to aquatic invertebrates is available  for HMDTMP(4-7K). However, a reliable study, performed with a H salt of ATMP, is available. A 28-day NOEC of ≥ 25 mg active acid/L was calculated for the effects of the test substance on the reproduction of Daphnia magna, according to an appropriate test protocol and in compliance with GLP.

Additional information

HMDTMP and ATMP are aminomethylenephosphonic acids. The identified phosphonates share a common chemistry incorporating alkyl backbones with one or more tertiary amine centres and multiple methylphosphonate groups present. Both acid and certain salt forms of these phosphonates behave no differently to each other and are fully dissociated in dilute aqueous conditions of defined pH, when presented at identical concentrations. In the course of their intended use, they form complexes with polyvalent metal ions. Both substances are strong chelators, with the ability to bind to inorganic surfaces. In the natural environment the fate and behaviour of these substances and their ions are dominated by abiotic dissociation / complexing, irreversible adsorption to surfaces, and less by degradation processes, and they will partition strongly to the solid phase of soil.

For further information on the read-across from ATMP to HMDTMP, please refer to IUCLID Section 13 and Annex 6 of the CSR.