Dipotassium [[N,N'-ethylenebis[N-(carboxylatomethyl)glycinato]](4-)-N,N',O,O',ON,ON']zincate(2-)

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

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

Principles of method if other than guideline:

The study was conducted according to the methods described by Branson DR, Blau GE, Alexander HC, and Neely WB (1975). Transactions of the American Fisheries Society, Vol. 104, No. 4: 785-792

GLP compliance:

no

Specific details on test material used for the study:

RADIOLABELLING INFORMATION
Specific activity 237 uCi/mg, labeled at the acetate group methyl carbon position

Radiolabelling:

yes

Vehicle:

no

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

Juvenile bluegill, Lepomis macrochirus, having an average wet weight of 0.49 g and a standard length ranging from 3.0 to 5.1 cm, were obtained from a commercial hatchery and maintained under laboratory conditions for a minimum of 2 weeks prior to testing. The fish were held in continuously flowing, carbon-filtered well water having a total hardness of 120 mg/L (as calcium carbonate). The fish were fed frozen brine shrimp twice daily. This was occasionally supplemented with feedings of live Daphnia. A 12-h photoperiod was maintained in the holding facilities.

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

28 d

Hardness:

120 mg/L as CaCo3

Test temperature:

21 °C

pH:

7.4

Dissolved oxygen:

near saturation

Details on test conditions:

The bioconcentration test system was based on that described by Branson et al..
The test chambers were 37-litre, all-glass aquaria fitted with removable glass covers.
A standpipe was used to maintain the water volume in the aquaria at 30 litres.
The tank effluents were collected in a common drain and filtered through activated carbon prior to their disposal.
A combination of incandescent and fluorescent lighting was controlled by an automatic timer to provide a 12 h photoperiod simulating dusk and dawn with graduating intensities.
The system provided a daylight intensity of approximately 350-550 cd (200-300 footcandles).
A 1 L proportional diluter was modified to deliver two concentrations of the test material.
A peristaltic pump or a multichannel syringe pump was used to meter the stock solutions directly into the diluter mixing chambers.
The entire diluter assembly was contained within a stainless steel housing to minimize the possibility of 14C contamination. All tests were conducted at 21 ± 2°C in carbon-filtered well water.
A flow rate of 10 litres/h, with a 95 percent replacement time of approximately 9 h, was sufficient to maintain the dissolved oxygen levels at greater than 60 percent of saturation.

Nominal and measured concentrations:

0.76 and 0.08 mg/L

Key result

Type:

BCF

Value:

ca. 1.8 dimensionless

Basis:

whole body w.w.

Time of plateau:

28 d

Calculation basis:

steady state

Remarks on result:

other: Conc. in environment / dose:0.08 mg/L

Type:

BCF

Value:

ca. 1.1 dimensionless

Basis:

whole body w.w.

Time of plateau:

28 d

Calculation basis:

steady state

Remarks on result:

other: Conc.in environment / dose:0.76 mg/L

Elimination:

yes

The measured concentrations of the test compound averaged approximately 80 percent of the nominal values. There was no substantial difference in measured concentrations during the kinetic (Cwk) and the plateau (Cwp) exposures; the coefficient of variation was less than 10 percent in all cases.

28-Day (Plateau) Method

At exposures of 0.76 and 0.08 mg/L, 14C-EDTA exhibited an extremely low bioconcentration potential.

During continous exposure up to 672 h, the EDTA concentration in fish did not exceed the EDTA concentration in water. The plateau BCF values for EDTA were approximately 1.1 at 0.76 mg/L and 1.8 at 0.08 mg/L, respectively and were independent of the exposure concentration for the range of values tested. After the transfer to clean water, there was an apparent difference between the two exposure levels in the rate of elimination of 14C activity. For fish exposed to 0.76 mg/L, approximately 81 percent of the accumulated 14C residues were eliminated within 336 h, for fish exposed to 0.08 mg/L, only 60 percent of the accumulated 14C residues had been eliminated within a comparable time. 

5-Day (Kinetic) Method

The rate constants calculated for 14C-EDTA were independent of the exposure concentrations, although the higher-level exposure may have been clearing somewhat faster. The projected equilibrium BCF values were similar to those observed in the plateau test and, again, serve to emphasize the extremely low bioconcentration potential of EDTA.

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

REPORTING FORMAT FOR THE CATEGORY APPROACH
Category justification document is attached in chapter 13.

Reason / purpose for cross-reference:

read-across source

Key result

Type:

BCF

Value:

ca. 1.8 dimensionless

Basis:

whole body w.w.

Time of plateau:

28 d

Calculation basis:

steady state

Remarks on result:

other: Conc. in environment / dose:0.08 mg/L

Key result

Type:

BCF

Value:

ca. 1.1 dimensionless

Basis:

whole body w.w.

Time of plateau:

28 d

Calculation basis:

steady state

Remarks on result:

other: Conc. in environment / dose:0.76 mg/L

Description of key information

Based on the estimated logKow (<3) and available BCF study in fish with radiolabelled EDTA (BCF range  1.1-1.8) it can be concluded there is low potential for bioaccumulation of EDTA-ZnK2.

Key value for chemical safety assessment

BCF (aquatic species):

1.8 L/kg ww

Additional information

Since no study investigating the bioaccumulation potential is available for Dipotassium zinc ethylenediaminetetraacetate (CAS No. 14689-29-3, EDTA-ZnK2), the assessment was based on a study conducted with subcategory 1 member Tetrasodium ethylenediaminetetraacetate (CAS No. 64-02-8) in a read across approach. This is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Grouping of substance and read across approach. Further justification for suitability of read across between subcategory 1 members is given within the category justification attached to chapter 13.

The key study was conducted according to the methods described by Branson et al. (1975; Transactions of the American Fisheries Society, 104(4): 785-792) and is similar to a flow through OECD 305 test (Bishop and Maki 1980). Acclimated fish were transferred to equilibrated test chambers, which contained nominal exposure concentrations of 1.0 and 0.1 mg/L EDTA. Fish and water samples were periodically collected for 14C analysis. The duration of the uptake phase for the kinetic tests was arbitrarily selected as 120 h (5 days). The uptake phase was continued for 672 h (28 days) for the plateau tests. Samples collected at 48 and 120 h were designated as the initial plateau samples.At exposures of 0.76 and 0.08 mg/L, 14C-EDTA exhibited extremely low 28d-whole fish bioconcentration factorsof 1.1 - 1.8. After transfer to clean water, elimination showed 81% at 0.76 mg/l and 60% at 0.08 mg/L in 14 days. In conclusion, the test substance did not bioaccumulate in fish. Based on the suitability of the read across approach this conclusion can also considered to be true for EDTA-ZnK2 (CAS No. 14689-29-3).