[[(phosphonomethyl)imino]bis[ethylenenitrilobis(methylene)]]tetrakisphosphonic acid, ammonium salt

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-03-28 to 2002-04-25

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

other: Test Method Relating to New Chemical Substances (1974, amended 1998)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)

GLP compliance:

yes

Details on sampling:

- Sampling intervals/frequency for test organisms: 4, 7, 14, 21, and 28 days

- Sampling intervals/frequency for test medium samples: 0, 4, 7, 14, 21, and 28 days

- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods):
- Four fish were taken from each concentration level and analysed two by two. Two fish are weighed, cut into pieces, and homogenised to a slurry. 15ml Acetonitrile, 5ml purified water and 0.2 ml of triethylamine were added to 1g of slurry. The solution was homogenised, centrifuged and the top layer collected and diluted to 50ml and then further diluted 20-fold with purified water. The solution was analysed by HPLC.
- The test media at high concentration was diluted ten-fold with purified water, then analysed by HPLC. The test media at low concentration was directly analysed by HPLC.

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

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Test substance dissolved in 2000ml purified water (High concentration level feed: 40000mg/l, low concentration feed: 4000mg/l). Each of feed solutions was supplied to a mixing glass tube by a metering pump, and diluted to their respective nominal concentrations by mixing with dilutionwater delivered by another type of metering pump, then poured into each test chamber.

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM
- Common name: Carp

- Source: Sankyo Suisan Co., 1-1, Ichigayatamachi, Shinjuku-ku, Tokyo, Japan, Lot #: 01-K-1112

- Age at study initiation (mean and range, SD): Less than a year after hatching

- Length at study initiation (length definition, mean, range and SD): 8±4 cm

- Weight at study initiation (mean and range, SD): About 5 g

- Health status: Preacclimation: When the lot of fish was received, visual observation was made and abnormal fish were removed. The remaining fish were then reared in an aquarium with water flowing through. During the acclimation period, fish were kept without receiving medicine in the aquarium.

- Description of housing/holding area: aquarium

- Feeding during test: 200ml/day

ACCLIMATION

- Acclimation period: ≥2 weeks

- Type and amount of food: Babygold® from Kyorin, The food was given in an amount of 2% of the fish weight.

- Health during acclimation (any mortality observed): Mortality during the 1 week before testing: (5%

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

28 d

Test temperature:

24±2°C

pH:

6.0-8.5

Dissolved oxygen:

260% of the saturation (25 mg/L at 240C)

Details on test conditions:

TEST MEDIUM / WATER PARAMETERS

- Intervals of test medium replacement: feed solutions were renewed after about 8 days.

OTHER TEST CONDITIONS

- Light intensity: About 16 hr/day (Hf fluorescent lamp with wavelengths of 400-700 nm)

Conc. / dose:

18.8 mg/L

Type:

BCF

Value:

< 10 dimensionless

Calculation basis:

steady state

Remarks on result:

other: Conc in environment

Remarks:

dose: High concentration level

Conc. / dose:

2.03 mg/L

Type:

BCF

Value:

< 94 dimensionless

Calculation basis:

steady state

Remarks on result:

other: Conc. in environment

Remarks:

dose: low concentration level

Details on results:

- Mortality of test organisms: <10%

- Behavioural abnormalities: There was no abnormality in shape of the body or in swimming and feeding behaviour during the period of the test.

Table 1: Concentration of the test substance in the test fish and bioconcentration factor (BCF) - High concentration level

Exposure period		Fish weight (g)		Peak Area (mAbs.sec)		Conc. In final solution (mg/l)	Conc. In fish body (µg/g)	Mean conc. In water (mg/l)	BCF
Day	No.	1	2	Sample	std
4	1	4.64	8.79	<1500	19910	<0.151	<166	18.8	<9
4	2	6.94	4.84	<1500	19910	<0.151	<166	18.8	<9
7	1	4.70	6.44	<1500	19834	<0.151	<167	19.0	<9
7	2	7.49	7.41	<1500	19834	<0.151	<167	19.0	<9
14	1	6.27	5.61	<1500	17767	<0.169	<186	18.9	<10
14	2	6.82	6.40	<1500	17767	<0.169	<186	18.9	<10
21	1	5.59	6.27	<1500	17767	<0.169	<186	18.7	<10
21	2	8.74	5.87	<1500	17767	<0.169	<186	18.7	<10
28	1	6.44	5.56	<1500	17767	<0.169	<186	18.8	<10
28	2	6.46	6.75	<1500	17767	<0.169	<186	18.8	<10

Table 2: Concentration of the test substance in the test fish and bioconcentration factor (BCF) - Low concentration level

Exposure period		Fish weight (g)		Peak Area (mAbs.sec)		Conc. In final solution (mg/l)	Conc. In fish body (µg/g)	Mean conc. In water (mg/l)	BCF
Day	No.	1	2	Sample	std
4	1	9.89	4.26	<1500	19910	<0.151	<166	2.06	<81
4	2	8.16	5.76	<1500	19910	<0.151	<166	2.06	<81
7	1	10.47	5.19	<1500	19834	<0.151	<167	2.01	<83
7	2	9.18	6.50	<1500	19834	<0.151	<167	2.01	<83
14	1	10.66	4.45	<1500	17767	<0.169	<186	2.00	<93
14	2	6.00	6.56	<1500	17767	<0.169	<186	2.00	<93
21	1	4.47	7.21	<1500	17767	<0.169	<186	1.99	<94
21	2	5.84	6.35	<1500	17767	<0.169	<186	1.99	<94
28	1	7.55	5.46	<1500	17767	<0.169	<186	2.03	<92
28	2	6.40	5.00	<1500	17767	<0.169	<186	2.03	<92

Both the final concentration in water and the concentration in fish body are at approximately the limits of detection of the analytical methods for those media.

Validity criteria fulfilled:

yes

Conclusions:

Bioconcentration factors of <10 (Concentration level 18.8 mg/l) and <94 (concentration level 2.03 mg/l) were determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Reference 2

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 4 of the CSR and IUCLID Section 13 for justification of read-across within the DTPMP category.

Reason / purpose for cross-reference:

read-across source

Conc. / dose:

18.8 mg/kg sediment dw

Type:

BCF

Value:

< 10 dimensionless

Calculation basis:

steady state

Remarks on result:

other: Conc. in environment

Remarks:

dose: High concentration level

Conc. / dose:

2.03 mg/kg sediment dw

Type:

BCF

Value:

< 94 dimensionless

Calculation basis:

steady state

Remarks on result:

other: Conc in environment

Remarks:

dose: low concentration level

Description of key information

No study of bioaccumulation with DTPMP-xNH₄ is available. These results are read across from DTPMP sodium salt. A reliable study of bioaccumulation of DTPMP(5-7Na) in carp, indicates a bioconcentration factor in the exposure phase of <10 (concentration level 18.8mg/l) and <94 (concentration level 2.03 mg/l).

Key value for chemical safety assessment

BCF (aquatic species):

94 dimensionless

Additional information

This conclusion is based upon a reliable study conducted with DTPMP(5-7Na) according to an appropriate test protocol, and in compliance with GLP.

In summary, on the basis of reliable experimental evidence in fish, DTPMP acid and its salts are not expected to bioaccumulate. Values for direct structural analogues (ATMP, HEDP) are less than 100. QSARs for bioaccumulation are not validated for phosphonates.

The ammonium ion upon release into the environment would enter natural nitrogen cycles in air, soil and water.

The acid and salts in the DTPMP category are freely soluble in water and, therefore, the DTPMP anion is fully dissociated from its cations when in solution. Under any given conditions, the degree of ionisation of the DTPMP 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 DTPMP-H, DTPMP (1-3Na), DTPMP (5-7Na), DTPMP (4-8K), DTPMP (xNH₄) or another salt of DTPMP.

 

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

1. DTPMP is present as DTPMP-H or one of its ionised forms. The degree of ionisation depends upon the pH of the media and not whether DTPMP-H, DTPMP (1-3Na), DTPMP (5-7Na), DTPMP (4-8K), DTPMP (xNH₄), or another salt was used for testing.

2. Disassociated ammonium, potassium or sodium cations. The amount of ammonium, potassium or sodium present depends on which salt was added.

3. Divalent and trivalent cations have much higher stability constants for binding with DTPMP than the sodium, potassium or ammonium 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 DTPMP-dication (e.g. DTPMP-Ca, DTPMP-Mg) and DTPMP-trication (e.g. DTPMP-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 DTPMP Category is considered to be valid.