Copper dibromide

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from June 1989 to June 1990

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:

Field research

Qualifier:

no guideline followed

Principles of method if other than guideline:

The study areas are shown in Fig. 1 together with more detailed insets of the estuaries indicating sampling locations. The survey period extended from June 1989 to June 1990. The Forth Estuary was sampled in June, August, November, January, March and May, the Tay in July, August, September, November, February, April and June. A small fast boat was used for sampling in the Tay Estuary and for the Forth Estuary west of the road and rail bridges, in the Firth of Forth a larger vessel was used (RS Forth Ranger). All surveys were undertaken at high water on spring tides. Samples were collected from a depth of 1 m using the sampler described by Balls & Laslett (1991). Only brief details of sampling and analytical procedures will be given here, further information s available elsewhere (Balls et al., 1994; Laslett & Balls, 1995). Trace metal samples were collected in acid cleaned polythene bottles and pressure filtered within 24 h onto preweighed acid washed 0.4 gm pore size polycarbonate membranes (Nuclepore). Membranes were washed free of salt with distilled water and air dried for SPM determination, they were subsequently digested with hot concentrated nitric acid for the determination of particulate trace metals. The precision of the method varied between metals but was generally in the range 10-15%.
In preparation for major element analysis by thin film X-ray fluorescence (XRF), aliquots of water were filtered through preweighed 37 mm diameter 0.4 gm pore size polycarbonate membranes (N clepore). The membranes were subsequently washed free of salt with distilled water and reweighed to assess their particulate loadings.
Samples for particulate organic carbon (POC) determination were collected in glass bottles and vacuum filtered through a 25 mm diameter Whatman GF/F filter in an all glass apparatus. Blanks were minimized by heating filters at 500°C for 2 h before use.
Filters were stored frozen and prior to the determination of POC (Perkin Elmer Elemental Analyser 240B) carbonate was removed by exposure to hydrochloric acid fumes.

GLP compliance:

no

Type of method:

other: X-Ray Fluorescence

Computational methods:

The partition coefficient (Kd) is calculated as Kd = Cp / Cd
(Cp and Cd are respectively the solubility of the metal and the concentration of the fine particles)

Key result

Type:

log Kd

Remarks:

overall mean

Value:

4.65 dimensionless

% Org. carbon:

8.2

Remarks on result:

other: mean % org. carbon

Remarks:

Results for Tay

Key result

Type:

log Kd

Remarks:

overall mean

Value:

4.78 dimensionless

% Org. carbon:

10.4

Remarks on result:

other: mean % org carbon

Remarks:

Results for Forth

Table 5.4.1.1: Distribution coefficient

	KDin the Forth Estuary		KDin the Tay Estuary
June 1989	4.89	July 1989	4.64
August 1989	4.72	August 1989	4.51
November 1989	4.75	September 1989	4.66
January 1990	4.73	November 1989	4.67
March 1990	4.85	February 1990	4.66
May 1990	4.72	April 1990	4.73
June 1990	4.89	July 1990	4.64
Overall mean + range	4.78 (4.72 - 4.89)		4.65 (4.51 - 4.73)

Table 5.4.1.2: Comparative results from other references

Area	Log KD-range	Reference
Rhine	4.1–5.0	Golimowskietal,1990
Waal	3.7–5.3	Golimowskietal,1990
Maas	4.7–5.8	Golimowskietal,1990
Weser	4.1	Turner et al, 1992
Seine	4.5–4.7	Chiffoleau et al, 1994
Mersey	4.7–5.0	Comber et al, 1995
Humber	3.8–3.9	Comber et al, 1995

Table 5.4.1.3: Suspended POC (%) in the Forth Estuary for individual surveys between June 1989 and June 1990

	% POC
	Min	Median	Max
June 1989	3.0	8.0	18.5
August 1989	5.8	10.0	13.9
November 1989	6.6	10.4	26.7
January 1990	3.9	12.5	37.5
March 1990	6.3	10.3	22.9
May 1990	4.7	11.1	35.9

Table 5.4.1.4: Suspended POC (%) in the Tay Estuary for individual surveys between June 1989 and June 1990

	% POC
	Min	Median	Max
July 1989	4.3	8.7	20.1
August 1989	4.7	8.9	23.2
September 1989	5.4	7.6	13.5
November 1989	4.2	10.5	19.4
February 1990	3.4	6.0	11.2
April 1990	2.7	6.5	8.2
June 1990	6.9	9.1	14.7

Validity criteria fulfilled:

not applicable

Conclusions:

The log Kd median values for Forth and Tay were 4.76 and 4.65, respectively. It is considered to be a substance adsorbed on the soil through this.

Executive summary:

The composition of dissolved and particulate trace elements was investigated in two North Sea estuaries (Forth and Tay). It was found that log Kd is higher than that of Forth in Tay, which may be related to the content of organic carbon in particulate matter. The log Kd median values for Forth and Tay were 4.76 and 4.65, respectively. It is considered to be a substance adsorbed on the soil through this.

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Remarks:

from the source substance copper

Adequacy of study:

supporting study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
A read-across based on analogue approach has been performed for that endpoint.
The read-across hypothesis, according to Read Across Assessment Framework published by ECHA, is based on the fact that different compounds which have the same type of effect(s). It corresponds to the scenario 2 described as follows:
« This scenario covers the analogue approach for which the read-across hypothesis is based on different compounds which have the same type of effect(s). For the REACH information requirement under consideration, the effects obtained in a study conducted with one source substance are used to predict the effects that would be observed in a study with the target substance if it were to be conducted. The same type of effect(s) or absence of effect is predicted. The predicted strength of the effects may be similar or based on a worst-case assumption. ».

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The read-across has been performed between copper dibromide (CAS No. 7789-45-9; target chemical) and copper (CAS No. 7440-50-8; source chemical).

3. ANALOGUE APPROACH JUSTIFICATION
Copper dibromide is decomposed into copper compounds and bromide ions in water. Bromide is not adsorbed and desorbed on sediments or suspended adsorbents because of its high water solubility. As a consequence, it can be considered that it is the copper compound that has the greater influence on the adsorption/desorption properties of the substance copper dibromide. There is no data available on the registered substance copper dibromide for this endpoint. Therefore, the results of adsorption and desorption tests, which is a study on the environmental distribution of copper compounds, were used.
Based on these elements and to the fact that both target and source chemicals are inorganic substances with close physical-chemical properties, it can be assumed that copper dibromide and copper may have similar environmental fate. The read-across approach between copper dibromide and copper is therefore relevant for this endpoint.

Reason / purpose for cross-reference:

read-across source

GLP compliance:

no

Conclusions:

Based on a read-across from the source substance copper, the target substance copper cyanide can be regarded as a substance adsorbed on the soil, with log Kd median values considered to be between 4.65 and 4.76.

Executive summary:

The composition of dissolved and particulate trace elements was investigated in two North Sea estuaries (Forth and Tay). It was found that log Kd is higher than that of Forth in Tay, which may be related to the content of organic carbon in particulate matter. The log Kd median values for Forth and Tay were 4.76 and 4.65, respectively. It is considered to be a substance adsorbed on the soil through this.

A read-across has been performed between copper cyanide (CAS No. 544-92-3; target chemical) and copper (CAS No. 7440-50-8; source chemical).

Indeed, copper cyanide is decomposed into copper compounds and cyanide in water. Cyanide is decomposed at high velocity and distributed as hydrogen cyanide. Hydrogen cyanide is not adsorbed and desorbed on sediments or suspended adsorbents because of its high water solubility. As a consequence, it can be considered that it is the copper compound that has the greater influence on the adsorption/desorption properties of the substance copper cyanide. There is no data available on the registered substance copper cyanide for this endpoint. Therefore, the results of adsorption and desorption tests, which is a study on the environmental distribution of copper compounds, were used.

Based on these elements and to the fact that both target and source chemicals are inorganic substances with close physical-chemical properties, it can be assumed that copper cyanide and copper may have similar environmental fate. The read-across approach between copper cyanide and copper is therefore relevant for this endpoint.

Therefore, the registered substance copper cyanide can be regarded as a substance adsorbed on the soil, with log Kd median values considered to be between 4.65 and 4.76.

Reference 3

Endpoint:

adsorption / desorption: screening

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

In accordance with column 2 of REACH Regulation (EC) No 1907/2006, Annex VIII, section 9.3.1, the test on adsorption/desorption screening does not need to be conducted as the substance can be expected to have a low potential for adsorption based on the octanol water partition coefficient. The theoretical, calculated (EPIWIN) log Pow is 0.23, i.e. very low, as expected for an inorganic substance.

Description of key information

In accordance with column 2 of REACH Regulation (EC) No 1907/2006, Annex VIII, section 9.3.1, the test on adsorption/desorption screening does not need to be conducted as the substance copper dibromide can be expected to have a low potential for adsorption based on the octanol water partition coefficient. The theoretical, calculated (EPIWIN) log Pow is 0.23, i.e. very low, as expected for an inorganic substance.

Key value for chemical safety assessment

Koc at 20 °C:

575 877

Additional information

As additional information, a study on an analogue substance was available and was used for CSA purpose. Indeed, the composition of dissolved and particulate trace elements was investigated in two North Sea estuaries (Forth and Tay). It was found that log Kd for copper is higher in Forth than in Tay, which may be related to the content of organic carbon in particulate matter. The log Kd median values for Forth and Tay were 4.76 and 4.65, respectively. The source substance copper is therefore considered to be a substance adsorbed on the soil through this.

A read-across has been performed between copper dibromide (CAS No. 7789-45-9; target chemical) and copper (CAS No. 7440-50-8; source chemical).

Indeed, copper dibromide is decomposed into copper compounds and bromide ions in water. Bromide is not adsorbed and desorbed on sediments or suspended adsorbents because of its high water solubility. As a consequence, it can be considered that it is the copper compound that has the greater influence on the adsorption/desorption properties of the substance copper dibromide There is no data available on the registered substance copper dibromide for this endpoint. Therefore, the results of adsorption and desorption tests, which is a study on the environmental distribution of copper compounds, were used.

Based on these elements and to the fact that both target and source chemicals are inorganic substances with close physical-chemical properties, it can be assumed that copper dibromide and copper may have similar environmental fate. The read-across approach between copper dibromide and copper is therefore relevant for this endpoint.

Therefore, the registered substance copper dibromide can be regarded as a substance adsorbed on the soil, with log Kd median values considered to be between 4.65 and 4.76.

Moreover, kd can be converted to koc with the following equation: kd = koc x foc (organic carbon fraction) <==> koc = kd / foc

In the study, the following organic carbon values have been reported:

Table 5.4.1.3: Suspended particulate organic carbon (POC, %) in the Forth Estuary for individual surveys between June 1989 and June 1990

	% POC
	Min	Median	Max
June 1989	3.0	8.0	18.5
August 1989	5.8	10.0	13.9
November 1989	6.6	10.4	26.7
January 1990	3.9	12.5	37.5
March 1990	6.3	10.3	22.9
May 1990	4.7	11.1	35.9

Table 5.4.1.4: Suspended POC (%) in the Tay Estuary for individual surveys between June 1989 and June 1990

	% POC
	Min	Median	Max
July 1989	4.3	8.7	20.1
August 1989	4.7	8.9	23.2
September 1989	5.4	7.6	13.5
November 1989	4.2	10.5	19.4
February 1990	3.4	6.0	11.2
April 1990	2.7	6.5	8.2
June 1990	6.9	9.1	14.7

Based on these tables, averaged POC values range betwwen 8.19% (Tay Estuary) and 10.38% (Forth Estuary).

Therefore, koc values are determined to be 539 440 L/kg (Tay Estuary) and 575 877 L/kg (Forth Estuary).

For CSA purpose, the most conservative value is used as the key koc value of the substance, i.e. 575 877 L/kg.