[nitrilotris(methylene)]trisphosphonic acid, sodium salt

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: fish

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 within the ATMP category.

Reason / purpose for cross-reference:

read-across source

Key result

Conc. / dose:

0.14 mg/L

Type:

BCF

Value:

22 L/kg

Basis:

non-edible fraction

Reference 2

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

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

Principles of method if other than guideline:

Flow-through study with radiolabelled test substance

GLP compliance:

no

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

STOCK AND TEST SOLUTION AND THEIR PREPARATION:  Super stock solutions were prepared by diluting known  amounts of labelled and unlabelled test substance with  distilled water. Diluter stock solutions were prepared  by further dilution with distilled water. Test solutions  were prepared using an intermittent-flow proprtional diluter. The specific activities of the super stock solutions were  determined to be: 0.14 mg/l stock: 335 ± 24 disintegrations per minute/µg 1.4 mg/l stock solution: 33.2 ± 2.5 dpm/µg

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISMS: Size: 19 ± 2 cm Weight: 39 ± 3 g Pretreatment: acclimated for 30 days before testing. Cumulative mortality less than 2% during holding period Feeding: Dry pelleted ration twice daily ad libitum

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

49 d

Total depuration duration:

14 d

Hardness:

35 mg/l as CaCO3

Test temperature:

18 ± 1.0 °C

pH:

7.1

Dissolved oxygen:

> 6.0 mg/l (60% saturation)

Nominal and measured concentrations:

Nominal: 0.14 mg/l and 1.4 mg/l
Mean measured: 0.14 mg/l and 1.2 mg/l

Key result

Conc. / dose:

0.14 mg/L

Type:

BCF

Value:

22 L/kg

Basis:

non-edible fraction

Elimination:

yes

BIOACCUMULATION AT 0.14 mg/l 

NOMINAL TEST CONCENTRATION: A mean fish concentration of 3.1 mg/kg, equivalent to BCF = 22, was  determined for non-edible tissues, although no meaningful trends in  bioaccumulation were observed at 7 sampling points over the exposure  period. Analysis of the gut, faeces and visceral 

tissues at Day 42 showed  that 72% of residues were present in faecal matter, 16% in the gut and  12% in the remaining visceral tissues, indicating that the substance was  ingested and eliminated with very little accumulation.  Expressed on a  whole-body basis,

the mean fish concentration was < 0.6 mg/kg, equivalent to BCF < 4.  

BIOACCUMULATION AT 1.4mg/l 

NOMINAL TEST CONCENTRATION: A similar pattern to the lower test concentration was The mean fish concentration determined for non-edible tissues was 12.2 mg/kg, equivalent to BCF = 10.  Analysis on Day 42 showed 45% in  faecal matter, < 5% in the gut and 50% in the remaining 

visceral tissues.  Accumulation in edible tissues was not observed.  ELIMINATION: Elimination of the test substance from non-edible tissues was rapid and  extensive. After the 14 day depuration, 96% of accumulated 

substance was eliminated at the 0.14 mg/l nominal test concentration; 93% was eliminated at the 1.4 mg/l nominal test concentration.

Conclusions:

BCF values of BCF <4 - 22 were determined in a reliable study conducted according to generally accepted scientific principles.

Description of key information

Based on the measured BCF 22 L/kg wwt, ATMP-xNa is not expected to bioaccumulate.

Key value for chemical safety assessment

BCF (aquatic species):

22 L/kg ww

Additional information

There is a report of bioaccumulation of ATMP-H in carp, with a bioconcentration factor in the exposure phase of <4 - 22 L/kg wwt (Monsanto, 1976). A secondary source reports results of a separate test as BCF = 17.7 measured for ATMP-H in Brachydanio rerio (zebra fish) (Steber and Wierich, 1987).

The acid, sodium, potassium and ammonium salts in the ATMP category are freely soluble in water. The ATMP anion can be considered fully dissociated from its sodium, potassium or ammonium cations when in dilute solution. Under any given conditions, the degree of ionisation of the ATMP 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 ATMP-H, ATMP.4Na, ATMP.7K or another salt of ATMP.

 

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

1. ATMP is present as ATMP-H or one of its ionised forms. The degree of ionisation depends upon the pH of the media and not whether ATMP (3-5K) salt, ATMP (3-5Na) salt, ATMP-H (acid form), or another salt was used for dosing.
2. Disassociated potassium, sodium or ammonium cations. The amount of potassium or sodium present depends on which salt was dosed.
3. It should also be noted that divalent and trivalent cations would preferentially replace the sodium or potassium ions. These would include calcium (Ca²⁺), magnesium (Mg²⁺) and iron (Fe³⁺). These cations are more strongly bound by ATMP than potassium, sodium and ammonium. This could result in ATMP-dication (e.g. ATMP-Ca, ATMP-Mg) and ATMP-trication (e.g. ATMP-Fe) complexes being present in solution.