[nitrilotris(methylene)]trisphosphonic acid, ammonium salt

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 306 (Biodegradability in Seawater)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Seawater collected from the Burnham-on-Crouch estuary at high water. The Crouch estuary has no inductrial and no river inputs and may be regarded as "clean". Suspended solids removed.

Duration of test (contact time):

28 d

Details on study design:

Closed bottle method.
The dilution water was prepared by the addition of mineral nutrient stock solutions to the seawater.
Replicate standard BOD bottles were filled with the test concentration, prepared by addition of a sample stock solution to dilution water. Blank = dilution water only.

Key result

% Degr.:

-2

Parameter:

CO2 evolution

Sampling time:

28 d

Transformation products:

no

Results with reference substance:

7d 64%
14d 69%
21d 72%
28d 75%

Average (2 or 3 replicates) degradation rates of test substance

7d       -8%

14d       -8%

21d       -9%       

28d       -2%

Conclusions:

Degradation of -2% in 28d was observed in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Reference 2

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 306 (Biodegradability in Seawater)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): A sample of natural seawater was taken from the Eastern Scheldt in the Netherlands (Yerseke) about 0.5 meters above the seabed; it was transported and stored in cleaned polythene carboys and filtered in the laboratory with a 45 Vm filter. The seawater was aerated until the start of the test.

Duration of test (contact time):

56 d

Initial conc.:

1 mg/L

Based on:

COD

Initial conc.:

2.5 mg/L

Based on:

COD

Details on study design:

Closed bottle method.
Blank and toxicity control.
pH 8.0 - 8.5
Temp 18.1 - 20.4°C

% Degr.:

41

Parameter:

O2 consumption

Sampling time:

28 d

Remarks on result:

other: Test material concentration 1 mg COD/l

% Degr.:

6

Parameter:

O2 consumption

Sampling time:

56 d

Remarks on result:

other: Test material concentration 1 mg COD/l

% Degr.:

22

Parameter:

O2 consumption

Sampling time:

28 d

Remarks on result:

other: Test material concentration 2.5 mg COD/l

% Degr.:

13

Parameter:

O2 consumption

Sampling time:

56 d

Remarks on result:

other: Test material concentration 2.5 mg COD/l

Transformation products:

not measured

Results with reference substance:

> 60% within 15 days

1 mg/l COD

5d       6%

15d     17%

28d      41%       

56d      6%

2.5 mg/l COD

5d       5%

15d     8%

28d     22%       

56d     13%

Conclusions:

Degradation rates of 22% to 41% in 28d were determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Reference 3

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

other: method detailed in STL Runcorn SOP III.36

Qualifier:

according to guideline

Guideline:

OECD Guideline 306 (Biodegradability in Seawater)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Natural seawater was collected from Anglesey Sea Zoo in North Wales on 19th May 2005. The seawater was coarse filtered and maintained in the dark. The seawater was aged prior to use by gentle aeration at 20 ± 2 °C.

Duration of test (contact time):

28 d

Initial conc.:

8 mg/L

Based on:

test mat.

Initial conc.:

10 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

Closed bottle method.
Incubations at 18.5 - 19.5 °C in the dark.

% Degr.:

21.7

Parameter:

DOC removal

Sampling time:

28 d

Remarks on result:

other: Degradation rates of test substance at 8 mg/l

% Degr.:

2.6

Parameter:

DOC removal

Sampling time:

28 d

Remarks on result:

other: Degradation rates of test substance at 10 mg/l

Transformation products:

not measured

Results with reference substance:

3d 75.2%
7d 99.6%
14d >100.0%
21d >100.0%
28d >100.0%

Degradation rates of test substance at 8 mg/l

3d       1.6%

7d       15.8%

14d      24.5%

21d      31.0%       

28d      21.7%

Degradation rates of test substance at 10 mg/l

3d       4.3%

7d       negative degradation indicated

14d     negative degradation indicated

21d      0.9%       

28d      2.6%

Conclusions:

Degradation rates of 2.6% to 21.7% in 28d were determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Reference 4

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.

Principles of method if other than guideline:

Natural Water Biodegradation and Photodegradation Monsanto shake flask system for CO2 evolution testing (W.E. Gledhill, App. Microbiol. 30, 922 (1975))

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on source and properties of surface water:

TEST DETAILS: Natural waters were obtained from the Meramec River (Kirkwood Park) (pH 7.4, TOC 12 mg/l) and Lake No. 34 - Busch Wildlife Area (pH 8.0, TOC 17 mg/l). These were allowed to settle for 2 days and the supernatant liquid used in 500 ml portions for the test.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Six water samples were spiked with a stock solution of the test substance to give a test concentration of 2 mg/l (active acid). Control flasks were similarly spiked with either C-14 labelled linear dodecylbenzene sulfonate (LAS) or glucose (glucose used only for lake water exposure as positive
control). Two of the replicates were then sterilised by the addition of 25 mg HgCl2.
An open reservoir containing 10 ml of 0.5N aqueous KOH was suspended in each flask. After sealing, one set of flasks was placed on a rotary shaker and agitated at 80 rpm at ambient temperature (22 °C) in the dark. A second set was taken to an outdoor platform and exposed to natural sunlight and temperatures.

% Degr.:

>= 9.5 - <= 15.3

Parameter:

CO2 evolution

Remarks:

(14CO2)

Sampling time:

60 d

Remarks on result:

other: Dark conditions

% Degr.:

>= 10 - <= 16.8

Parameter:

CO2 evolution

Remarks:

(14CO2)

Sampling time:

60 d

Remarks on result:

other: In active conditions with sunlight

Transformation products:

not measured

Table 1: Percent degradation values at 60 days for reference substances and test substance in river water and lake water

Type of suspension	% degradation at 60 days
	River Sterile	Lake Sterile	River Sterile plus light	Lake Sterile plus light	River microbial	Lake microbial	River Microbial plus light	Lake Microbial plus light
Reference Linear dodecylbenzene sulfonate	3.67	1.19	3.60	1.92	32.08	6.34	1.88	15.35
Reference                       Glucose (Lake only)	-	0.31	-	1.15	-	58.82	-	46.66
Test substance	0.13	0.05	3.11	9.21	9.53, 10.13	15.32, 14.91	10.76, 10.00	16.74, 16.81

 

The effect of temperature variation in the sunlight exposures is an unknown factor. Water temperature reached as high as 44 °C during the test. This may have had a significant impact on the microbial population and distribution.

In general, the lake water appeared somewhat more active than the river water with respect to the test substance degradation.

For LAS, the reverse was true. Much more acclimation from previous exposure to LAS in the river than the lake would be
expected. The reason for the higher activity of the lake water to the test substance is unknown.

Conclusions:

A degradation rate in river and lake waters of ca. 10 - 15% after 60 days was determined in a reliable study conducted according to generally accepted scientific principles.

Reference 5

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

Natural water - sediment microcosms. C14 labelled.

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on study design:

Microcosms simulating natural water environment constructed using 10 -gallon aquaria and a core-chamber technique. Water and sediment from littoral region of a spring fed freshwater lake (Lake 34 water, Busch Wildlife Area, St Charles County, Missouri). 8 litres sediment; 22 litres water. Microcosms were allowed to stabilise for periods ranging fom one month to four months, with gentle aeration and a 16/8 hr light/dark cycle.

pH 8.4 -8.6; conductivity 420 -460 µmhos; dissolved O2 6.5 - 7.5 before coring.

At the end of stabilization period, core chambers were created by inserting sterile glass cylinders (3.8 x 30 cm) through the water column and sediment onto silicone stoppers. Each chanber contained 150 -175 ml water and 20 - 60 g sediment (dwt). Gas manifolds supplied either CO2 -free air or oxygen-free nitrogen about 5cm above the sediment surface. Exhaust gas was passed through a resin trap to remove volatilised organics and then through a CO2 scubbing system.

Sterile microcosms: core chambers were removed from the aquaria, and water and sediment autoclaved seperately and recombined, and 1 ml sodim azide was added.

C-14 labeled test substance (Dequest 2001) added to give 1000 ppb.

Samples of water column removed at day 0 and periodically thereafter and analysed for C14 activity. At end of test sediment dry weight determined and sediment burned in an oxidizer to determine C14 activity.

Key result

% Degr.:

5 - 12

Parameter:

radiochem. meas.

Sampling time:

28 d

Transformation products:

no

>90% decrease in water column C14 activity after 10d. Microcosm variables: aeration vs nitrogen purge; light vs dark; active vs sterile, did not seem to significantly affect the rate of removal from the water column. Indicates non-degradative mechanism dominates removal from water column. Autoclaving sodium azide treatment was not adequate for sterilisation.

In active, aerated systems, CO2 evolution ranged from 5 to 12%. In active nitrogen purged system, the CO2 evolution ranged from 1 to 5%. C14 activity was not extracted to any significant degree with acidified acetone (unextracted and extracted had similar % of theory, and extract had low %)

Conclusions:

A degradation rate in a water-sediment microcosm of 5 - 12 % after 28 days (1 - 5% under anaerobic conditions) was determined in a reliable study conducted according to generally accepted scientific principles.

Reference 6

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 306 (Biodegradability in Seawater)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): A sample of natural seawater was collected from the Eatern Scheldt in the Netherlands (Jacobahaven) about 2.5 meters above the sea bed. After sedimentation of the coarse particle the seawater was decanted over a sieve and aerated until start of test.

Duration of test (contact time):

56 d

Initial conc.:

18.2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Closed bottle method.
Incubations at 20.0 - 20.6 °C. pH 7.9-8.0.

% Degr.:

8

Parameter:

O2 consumption

Remarks:

Relative to theoretical oxygen demand

Sampling time:

28 d

% Degr.:

11

Parameter:

O2 consumption

Remarks:

Relative to chemical oxygen demand

Sampling time:

28 d

% Degr.:

18

Parameter:

O2 consumption

Remarks:

Relative to theoretical oxygen demand

Sampling time:

56 d

% Degr.:

23

Parameter:

O2 consumption

Remarks:

Relative to chemical oxygen demand

Sampling time:

56 d

Transformation products:

no

Results with reference substance:

Rapid degradation (almost complete within five days).

Degradation rates of test substance (relative to COD)

5d       1%

15d      <0%

28d      11%       

56d      23%

Degradation rates of test substance (relative to ThOD(NO3))

5d       1%

15d      <0%

28d      8%       

56d      18%

Conclusions:

A degradation rate of 23% (relative to COD) and 18% (relative to ThOD) in 56d was determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Reference 7

Endpoint:

biodegradation in water: sediment simulation testing

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 within the ATMP 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

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

% Degr.:

2.6 - 21.7

Parameter:

DOC removal

Sampling time:

28 d

Remarks on result:

other: Rowlands (2005)

% Degr.:

22 - 41

Parameter:

O2 consumption

Sampling time:

28 d

Remarks on result:

other: Hamwijk and Cremers (2005)

% Degr.:

6 - 13

Parameter:

O2 consumption

Sampling time:

56 d

Remarks on result:

other: Hamwijk and Cremers (2005)

% Degr.:

>= 9.5 - 16.8

Parameter:

CO2 evolution

Remarks:

(14CO2)

Sampling time:

60 d

Remarks on result:

other: Saeger (1978)

Remarks:

under different conditions (light and dark)

% Degr.:

5 - 12

Parameter:

radiochem. meas.

Sampling time:

28 d

Remarks on result:

other: Saeger (1979)

% Degr.:

-2

Parameter:

CO2 evolution

Sampling time:

28 d

Remarks on result:

other: Drake (2005)

% Degr.:

8 - 11

Parameter:

O2 consumption

Remarks:

relative to theoretical/chemical oxygen demand

Sampling time:

28 d

Remarks on result:

other: Muttzall and Hanstveit (1996)

% Degr.:

18 - 23

Parameter:

O2 consumption

Remarks:

relative to theoretical/chemical oxygen demand

Sampling time:

56 d

Remarks on result:

other: Muttzall and Hanstveit (1996)

Transformation products:

no

Description of key information

Two reliable simulation studies of ATMP-H in water and sediment systems are available, which have been read-across (Saeger, 1978 and 1979). Low but recordable levels of removal are seen in such systems, particularly in the presence of natural or simulated light.

 

Although biodegradation in sediment has not been demonstrated for ATMP-H and its salts, the role of abiotic removal processes is significant. The key data for soil adsorption are from the study by Michael (1979, refer to IUCLID Section 5.4.1). There is no evidence for desorption occurring. Effectively irreversible binding is entirely consistent with the known behaviour of complexation and binding within crystal lattices. The high levels of adsorption which occur are therefore a form of removal from the environment. For analogous phosphonate complexing agents, after 38-50 days, the phosphonate is >95% bound to sediment with only 5% extractable by ultrasonication and use of 0.25N HCl xylene solvent (based on radiolabelling) in river microcosms (cited in Gledhill and Feijtel, 1992). In the same study, ATMP-H rapidly, and to a high degree was irreversibly removed from a natural water column. (Saeger, 1979, also see IUCLID section 5.4.1). In the context of the exposure assessment, largely irreversible binding is interpreted as a removal process; 5% remaining after 40 - 50 days is equivalent to a half-life of 10 days which is significant for the environmental exposure assessment in the regional and continental scales. This abiotic removal rate is used in the chemical safety assessment of ATMP-H and its salts.

Key value for chemical safety assessment

Half-life in freshwater:

10 d

at the temperature of:

12 °C

Half-life in marine water:

10 d

at the temperature of:

12 °C

Half-life in freshwater sediment:

10 d

at the temperature of:

12 °C

Half-life in marine water sediment:

10 d

at the temperature of:

12 °C

Additional information

Reliable data are available ATMP-H and ATMP-xNa for degradation in natural freshwaters and marine waters, which have been read-across. Minimal degradation is indicated:

Biodegradation of ATMP-H in a water-sediment microcosm of 5 - 12 % after 28 days (1 - 5% under anaerobic conditions) was determined (Saeger 1979).

Biodegradation of ATMP-H in river and lake waters of ca. 10 - 15% after 60 days was determined (Saeger 1978).

Biodegradation in seawater values have been recorded for ATMP-H: -2% in 28 days (Drake 2005), 2.6% to 21.7% in 28 days (Rowlands 2005), 22% to 41% in 28 days and 6% to 13% in 56 days (Hamwijk and Cremers 2005) and one study for ATMP-xNa is available: 18 -23% in 56 days (Muttzall and Hanstveit 1996).

Identification of degradation products:

The registrants consider that the possible benefits to the CSA of conducting further studies of the formation of degradation products are not significant in comparison with the foreseeable difficulties to conduct and interpret the studies.

Isolating and identifying degradation products presents a significant analytical challenge. There is substantial evidence across most types of phosphonates of rapid and irreversible binding to solids, particularly inorganic substrates (please refer to IUCLID Section 5.4). It is difficult to envisage an analytical system suitable for extracting and analysing the substances which could not be affected by this. Secondly, the relevance of the data must be considered. Whilst there is limited degradation in the environment, it is not extensive or rapid under standard conditions. Removal processes from natural waters are attributed to the typically rapid, irreversible adsorption to solid matrices. As such the chemical safety assessment for the environment focuses on the parent substance. There are no unacceptable risks (please refer to CSR Chapter 10). The substance is not classified for environmental hazard, and is not PBT or vPvB. Inorganic impurities present are not biodegradable.

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

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.

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