Nitrilotrimethylenetris(phosphonic acid)

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: short-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1995-07-28 to 1995-10-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to a national standard method, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

other: PARCOM guideline. Paris Commission Ring Test protocol (1993)

Deviations:

yes

Remarks:

sediment criteria grain size (min grain size 63 rather than 90 um), and silt clay fraction (26.9% rather than 5-20%). It is not considered by the authors to have adversely affected the outcome of the test. See below for further details on deviations.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)

Deviations:

yes

Remarks:

see below for details.

Principles of method if other than guideline:

Deviations (contd.):
- no range finding test
- no twilight period
- test substance was not determined in solution

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT

- Details of spiking: adequate amounts of the test substance were weighed and added to glass mixing jars containing ca. 712.5 g of damp natural sediment (ca. 350 g dry sediment). As the sediment was adjudged to be damp enough already to mix easily, natural seawater was not added. The jars were sealed and rolled. Portions of about 75 ml of the spiked and control sediments were placed in each of 4 replicate test vessels which were carefully topped up to 225 ml with natural seawater so as not to disturb the sediment layer. A slight aeration was started and 5 randomly chosen test animals were introduced to each test vessel.

- Equilibration time: ca. 24 h

- Equilibration conditions: rolled on a roller bank at about 15°C.

- Controls: Natural sediment treated in the same way as the spiked sediments was used as a control.

Test organisms (species):

Corophium sp.

Details on test organisms:

TEST ORGANISM

- Source: Southern shore of Oosterschelde, The Netherlands.

- Details on collection: collected near the intake point where TNO collects its seawater, close to a break in the former sea dike where a trickle of freshwater emerges. The organisms had a length of ca. 5-8 mm.

Study type:

laboratory study

Test type:

static

Water media type:

saltwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

10 d

Exposure phase:

total exposure duration

Post exposure observation period:

none

Hardness:

Not reported

Test temperature:

range: from 14.9 to 15.8°C

pH:

range: from 7.9 to 8.1

Dissolved oxygen:

Lowest value was 7.1 mg/L

Salinity:

range: 30.4 to 33.2%o

Ammonia:

Not reported.

Nominal and measured concentrations:

Nominal concentrations: 100, 320, 1000, 3200 and 10000 of test material per kg dw.
The results are expressed as active acid. Equal to nominal concentrations: 29.1, 93.1, 291, 931 and 2,910 mg active acid/kg dw.

Details on test conditions:

TEST SYSTEM

- Test container (material, size):glass beakers with a volume of ca. 250 ml.

- Sediment volume (weight): ca. 350 g dry spike sediment

- Aeration: yes



EXPOSURE REGIME

- No. of organisms per container (treatment): 5

- No. of replicates per treatment group: 4

- No. of replicates per control: 4



OVERLYING WATER CHARACTERISTCS

- Type of water: natural sea water

- Source of water (if non-standard medium)

- Location: from the Eastern Scheldt, Netherlands.

- Description of sampling site: unpopulated area

- Filtration: filtered through sand upon arrival and checked for concentration of volatile organic compounds, and mineral oil. Each batch of seawater is also checked for gross pollution before use in a four day test with the crustacean Mysidopsis bahia. Before using the water was filtered over a carbon filter and a 5µm membrane filter.


- Salinity:32%o


SOURCE OF NATURAL SEDIMENT

- Location and description of sampling site: same location as test animals.



CHARACTERIZATION OF SEDIMENT

- Particle size distribution: median grain size 63-125 µm, silt clay <63 µm

- Sediment sieved: yes at 0.5 mm on arrival to remove predators, broken shell and larger particles.

- Total organic carbon (%): total organic matter content 2.8% (weight loss on ignition)



OTHER TEST CONDITIONS

- Photoperiod: 16 h light-8 h dark regime with transition periods of 30 minutes.



EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mortality, recorded on day 5 and on day 10



TEST CONCENTRATIONS

- Spacing factor for test concentrations: 3

Reference substance (positive control):

no

Duration:

10 d

Dose descriptor:

LC50

Effect conc.:

> 2 910 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Duration:

10 d

Dose descriptor:

LC50

Effect conc.:

> 10 000 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

>= 2 910 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Details on results:

- Mortality of test animals at end of exposure period: max 10% average, see Table 1 for details.

- Behavioural abnormalities: the animals are said by the authors to have a condition (general behaviour) equal to that of the control animals.

Reported statistics and error estimates:

Since mortalities were within 10% (average) no statistical analysis was generated.

Table 1: Effect of test substance on mortality of Corophium sp.

Nominal concentration (mg/kg dw)		Day 5		Day 10
		No. alive	% mortal.	No. alive	% mortal.
Control	Replicate #1	5	0	5	0
	Replicate #2	5	0	4	20
	Replicate #3	5	0	5	0
	Replicate #4	5	0	4	20
100	Replicate #1	5	0	5	0
	Replicate #2	5	0	5	0
	Replicate #3	5	0	5	0
	Replicate #4	5	0	5	0
320	Replicate #1	5	0	5	0
	Replicate #2	5	0	5	0
	Replicate #3	5	0	4	20
	Replicate #4	5	0	5	0
1000	Replicate #1	5	0	5	0
	Replicate #2	5	0	4	20
	Replicate #3	5	0	4	20
	Replicate #4	5	0	5	0
3200	Replicate #1	5	0	5	0
	Replicate #2	5	0	4	20
	Replicate #3	5	0	4	20
	Replicate #4	5	0	5	0
10,000	Replicate #1	5	0	5	0
	Replicate #2	5	0	5	0
	Replicate #3	5	0	5	0
	Replicate #4	5	0	5	0

 

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.

Validity criteria fulfilled:

yes

Conclusions:

A 10 day LC50 value of >2,910 mg active acid/kg dw has been determined for the effects of the test substance on mortality of the marine sediment dwelling organism Corophium sp. Similarly, a 10 day LC50 value of >10,000 mg whole test substance/kg dw has been determined for the effects of the test substance on mortality of the marine sediment dwelling organism Corophium sp.

Description of key information

Supporting study: A 10-day LC₅₀ value of >2910 mg active acid/kg dw has been determined for the effects of ATMP-H on mortality of the marine sediment dwelling organism Corophium sp.

Supporting study: a 10-day LC₅₀ value of >5000 mg/kg dw has been determined for the effects of ATMP-H on the mortality of the marine sediment dwelling organism, Corophium volutator.

Additional information

There are no long-term data available for sediment dwelling organisms.

In a supporting short-term sediment toxicity test, a 10-day LC₅₀ value of >2910 mg active acid/kg dw has been determined for the effects of ATMP-H on mortality of the marine sediment dwelling organism Corophium sp. (TNO, 1997).

In a second supporting short-term sediment toxicity test, a 10-day LC₅₀ value of >5000 mg /kg dw, nominal concentration, has been determined for the effects of ATMP-H on mortality of the marine sediment dwelling organism Corophium volutator (Zeneca, 1995).

No test data are currently available for freshwater sediment-dwelling organisms.

In accordance with Column 2 of REACH Annex X, there is no need to further investigate the effects of this substance to sediment dwelling organisms because, as indicated in REACH guidance R7b Section R.7.8.14 (ECHA, 2017), the quantitative chemical safety assessment (conducted according to Annex I of REACH) indicates that the Risk Characterisation Ratio is below 1, therefore the risk is already adequately controlled and further testing is not justifiable. An additional factor of 10 is applied to the screening assessment when undertaking risk characterisation based on equilibrium partitioning PNEC for sediment for substances which have log K_ow >5. This is to account for additional exposure via ingestion of adsorbed substance on particles and it is therefore scientifically appropriate to consider making a similar adjustment for substances which have binding or adsorption properties indicating highly adsorbing behaviour, equivalent to a high log K_ow. Phosphonates are highly adsorbing even though the log K_ow value is extremely low, as discussed in IUCLID Section 5.4. In view of the tendency to bind irreversibly to the inorganic substrate; the generalised lack of uptake and rapid clearance from the body associated with oral exposure, and low bioaccumulation potential, these are strong arguments against a need to make such an adjustment to RCR values. On this basis, the extra factor of 10 is not applied in this assessment. The substance is involatile and highly adsorbing and low toxicity was observed in short and long-term aquatic tests, and there is no reason to expect effects in the sediment compartment that were not expressed in the aquatic compartment. The phosphonate ligand binds strongly and irreversibly to various minerals present in sediment and so bioavailability to sediment organisms is extremely limited. The PNEC calculated by Equilibrium Partitioning has been derived for the purpose of conducting a chemical safety assessment, and the risk characterisation ratios are below 1. Furthermore, results are available for short-term effects on marine sediment-dwelling organisms. A reliable 10-day LC₅₀ value of >2910 mg active acid/kg d.w. has been determined for the effects of ATMP-H on mortality of Corophium sp. A second result of >5000 mg/kg d.w. is also available. The results indicate that ATMP acid has low toxicity to sediment-dwelling organisms following short-term exposure. Details on how the PNEC and the risk characterisation ratio have been derived can be found in IUCLID Section 6.0 Ecotoxicological Information and Chapters 9 and 10 of the Chemical Safety Report, respectively.