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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2002-03-28 to 2002-04-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to a test protocol that is comparable to the appropriate OECD test guideline, and in compliance with GLP.
Qualifier:
according to
Guideline:
other: Test Method Relating to New Chemical Substances (1974, amended 1998)
Qualifier:
equivalent or similar to
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 adn 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 (lenght 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 anaquariumwithwater 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)
Type:
BCF
Value:
< 10 dimensionless
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:High concentration level (18.8mg/L)
Type:
BCF
Value:
< 94 dimensionless
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:Low concentration level (2.03mg/l)
Details on results:
- Mortality of test organisms: <10%

- Behavioural abnormalities: There was no abnormality in shape of the body or in swimming and feeding behavior 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

Validity criteria fulfilled:
yes
Conclusions:
Bioconcentration factors of <10 (Concentration level 18.8mg/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.
Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
HMDTMP is an example of the aminomethylenephosphonic acid class. In the context of the RAAF, read-across of environmental, ecotox human health and physicochemical data within the group of aminomethylenephosphonates is considered as Scenario 2.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The aminomethylenephosphonates are registered phosphonates which share a common chemistry incorporating alkyl backbones with one or more tertiary amine centres and multiple methylphosphonate groups present. HMDTMP acid (CAS 23605-74-5) has two aminobismethylphosphonate groups, connected by a hexyl chain. DTPMP acid (CAS 15827-60-8) has five methylphosphonate groups attached to three amino nitrogen atoms which are connected by ethyl chains. Typically, impurities include residual inorganic acids/salts and organic by-products from manufacturing.
As well as being structural analogues, both phosphonates have consistent chemical properties including high MW (492 and 436 respectively), very low log Kow (≤-4 for both substances) and are highly soluble in water. The substances generally possess similar physicochemical properties and are not readily biodegradable or bioaccumulative.
The sodium and potassium counterions of these phosphonates are not significant in respect of the properties under consideration and have been assessed in depth in the public literature. Additionally, the counterions are expected to dissociate when in contact with water, including atmospheric moisture.

3. ANALOGUE APPROACH JUSTIFICATION
The justification of the aminomethylenephosphonates as a group is primarily made on the grounds that 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 are substances for REACH registration.
In the present context the effect of the alkaline metal counter-ion (sodium or potassium) will not be significant. For ammonium salts, the role of ammonia is given due consideration.
In biological systems and the environment, polyvalent metal ions will be present, and the phosphonate ions show very strong affinity to them.
The aminomethylenephosphonates are consistent in their physicochemical properties. The acid and salt forms of all the phosphonates are all of relatively high solubility in water (in general, more than 100 g/l), very low octanol-water partition coefficient (<0). The relatively high proportions of the phosphonate groups relative to the number of carbon atoms confers something of an inorganic quality to the substances.
The aminomethylenephosphonates are susceptible to biodegradation but only small fractions are removed in standard tests. They undergo photodegradation and bind strongly and effectively irreversibly to substrates including soil and sediment. They show low bioconcentration in fish. The behaviour of phosphonates in the environment will be profoundly affected by their concentration in water, the concentration and identities of metal ions, and the solids content per unit volume of water. From surface water through to soil a wide range of these parameters will be exhibited.
The aminomethylenephosphonates are typically not of high ecotoxicity to fish and invertebrates under neutral conditions, probably due to low bioavailability. Effects caused in aquatic plants (algae) are due to complexation of minerals and is not relevant in the wider environment.

4. DATA MATRIX
A data matrix table of all the data available on the various aminomethylenephosphonates is available in Section 13 of the technical dossier.
Reason / purpose:
read-across source
Conc. / dose:
2.03 mg/L
Type:
BCF
Value:
< 94 dimensionless
Calculation basis:
steady state

Description of key information

No study of bioaccumulation conducted with HMDTMP (4 -7Na) is available. Given the very low estimated value of log Kow (-4), bioaccumulation is expected to be very low. A reliable study of bioaccumulation of DTPMP-7Na in carp, indicates a bioconcentration factor in the exposure phase of <10 (Concentration level 18.8 mg/l) and <94 (concentration level 2.03 mg/l). No active uptake mechanisms (i.e. mediated by enzymes) can occur for phosphonates.

Key value for chemical safety assessment

BCF (aquatic species):
94 dimensionless

Additional information

The registration substance is part of an analogue group (aminomethylenephosphonates analogue group; see CSR for more details) which consists of several phosphonates that share a common chemistry incorporating alkyl backbones with one or more tertiary amine centres and multiple methylphosphonate groups present. Where measured aquatic bioaccumulation studies are available they consistently demonstrate low bioconcentration factors in fish, consistent with the substances’ very low log Kow values. These data present a strong case against any need to conduct further fish bioaccumulation testing for the registration substance. The registration endpoint is fulfilled by read-across within the analogue group.

 

HMDTMP acid (CAS 23605-74-5) has two aminobismethylphosphonate groups, connected by a hexyl chain. DTPMP acid (CAS 15827-60-8) has three amine centres (five methylphosphonate groups), connected by ethyl chains.

 

As well as being structural analogues, both phosphonates have consistent chemical properties including high MW (492 and 573 respectively), very low log Kow(≤-3 for both substances) and are highly soluble in water. The substances generally possess similar physico-chemical properties and are not readily biodegradable.

 

The sodium counterions of these phosphonates are not significant in respect of the properties under consideration and have been assessed in depth in the public literature. Additionally, the counterions are expected to dissociate when in contact with water, including atmospheric moisture.

 

Therefore, for the purpose of this assessment, read-across is considered valid. Further information on the aminomethylenephosphonates analogue group and the validity of read-across are presented in the CSR Chapter 1.