Copper cyanide

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to fish, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline followed

Principles of method if other than guideline:

In this study was examined whether growth responses in rainbow trout fry exposed to waterborne Cu could be related to whole-body Cu accumulation and/or exposure duration. The specific objectives of the laboratory study were to determine the sensitivity of growth responses in rainbow trout exposed to sublethal Cu concentrations and to determine whether prolonged exposure resulted in increased whole-body Cu accumulation and/or MT concentrations.

GLP compliance:

not specified

Analytical monitoring:

yes

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

60 d

Hardness:

24.6 mg/l CaCO3

Test temperature:

9.8°C

pH:

7.5

Nominal and measured concentrations:

- Nominal: 0, 0.6, 1.2, 2.5, 5.0, 10.0 μg/l
- Measured: 0.9, 1.1, 2.2, 4.6, 9.0 μg Cu/l

Details on test conditions:

EXPERIMENTAL DESIGN, EXPOSURE WATER AND SYSTEM
A randomized block design was used to assign control and Cu exposure dilutions to aquaria. Exposure treatments consisted of six total Cu levels (nominal 0.0, 0.6, 1.2, 2.5, 5.0, or 10.0 ug/L). Each block contained one replicate of each exposure dilution and a control; six blocks were used, for a total of 36 aquaria. Cu concentrations were achieved by metering (Fluid Metering, Inc., QG-20 Laboratory pump) a Cu stock solution via Mariotte bottles into the dilution box of a continuous-flow, proportional diluter. The stock solution was prepared from reagent grade Cu salt (CuCl2*6H20) dissolved in deionized water.
The proportional diluter delivered exposure and control waters to each aquarium at 0.2 L/min, providing a flow rate of 288 L/day (36 volume renewals/day) and a 90% volume replacement time of less than 1.5 h (Sprague, 1969). Waters were formulated by continuously mixing well and deionized water (well water treated with sediment filtration, reverse osmosis, and separate-bed deionization) to attain the following nominal water quality conditions: hardness, 25 mg/L as CaC03 ; alkalinity, 25 mg/L as CaCO,; pH, 7.5; temperature, 10°C. Fiberglass headtanks (190 L; Frigid Units, Inc.) continuously received the formulated water that was adjusted to the desired pH by automatic pH analyzer/controllers (Leeds and Northrup model 7084) using dilute HzS04 and KOH.
Temperature and pH were monitored and recorded continuously with a Hewlett Packard (model 3497A) data acquisition and alarm system. Exposure and control waters were analyzed daily to ensure that the water quality parameters were within 10% of the desired levels for hardness, alkalinity, pH, dissolved oxygen, and temperature.


TEST PROCEDURE
Rainbow trout (Oncorhynchus mykiss) eyed eggs were obtained from a hatchery source and were hatched at the laboratory in incubators using well water (hardness, 220 mg/L as CaC03 ; alkalinity, 180-210 mg/L as CaC03 ; pH, 7.2-7.8; temperature, 4°C). After hatching, the trout were transferred to circular holding tanks and acclimated for more than 14 days to the control water used in the bioassay (hardness, 25-30 mg/L as CaCO,; alkalinity, 22-28 mg/L as CaCO,; pH, 7.3-7.6; temperature, 10°C). Fish condition and health were monitored daily, and fish remained disease-free; there was no mortality during acclimation to soft water. At the swim-up stage, trout were fed frozen BioDiet trout food once daily at a ration in excess of 4.5% (wet wt. food/wet wt. body). Throughout the Cu exposures, the trout were maintained at 4.5% rations; this was determined daily for each exposure concentration based on the average biomass per replicate. Approximately 3 h after feeding, each aquarium was siphoned to remove debris. Mean (+/- SD) Cu content of the diet used in this study was 8.7 2 0.9 mg/kg, wet wt. (n = 3). A 12 h light/dark cycle was used throughout the study. At the initiation of the bioassay, swim-up fry had a mean (+/- SD) wet weight of 0.120 +/- 0.031 g (n = 60) and a total length of 25.7 +/- 2.2 mm (n = 60). The fry were transferred from holding tanks to exposure aquaria and continuously exposed to Cu concentrations for 60 days. Fry were observed daily to evaluate mortality and abnormal locomotory and feeding behaviors. At 20-day intervals, ten live fish from each replicate were collected and sacrificed for measurement of wet weight, total length, whole-body Cu concentration, and whole-body MT concentration.

After the weight and length measurements, the ten fish within each replicate were combined and ground under liquid nitrogen with a stainless steel mortar and pestle.
Ground tissue samples were split into two aliquots and stored at -70°C for further processing. Aliquots for Cu concentration determinations were lyophilized to constant dry weights and digested in 30% HNO3 (Instra-Analyzed). Digested tissues were brought to volume with deionized water and analyzed for Cu concentrations with atomic absorption spectrophotometry (AAS) using a Varian Spectra AA-600 equipped with graphite furnace and Zeeman background correction (method detection limit for Cu, 0.9 ug/L). Aliquots for MT determinations were partially thawed, weighed, and homogenized in 50 mM Tris-HCl (pH 8.0, 1°C at a minimum of 1:3 weight:volume ratio). The homogenate was centrifuged at 8800 rev /min, 4°C for 10 min. Then, 100 ul of each supernatant were extracted, frozen in liquid nitrogen, and stored at -70°C for MT analysis. MT concentrations were determined by a competitive double-antibody radioimmunoassay (RIA) (Hogstrand and Haux, 1990) as modified for rainbow trout MT by Hogstrand et al. (1994).

Water samples were collected every 3-6 days from randomly determined replicate tanks to determine water quality parameters, Cu concentrations, and concentrations of major cations and anions. Water samples (25 ml) for Cu and other cation analyses were preserved with 25 uL of 70% HN03 (Instra-Analyzed grade) and analyzed using either graphite furnace AAS or flame AAS (Perkin-Elmer model 2380). Water samples (25 ml) for anion analyses were stored at 4°C in the dark and analyzed using ion chromatography. Method detection limits for the cations and anions were as follows: Cu, 0.9 ug/L ; Ca, 0.09 mg/L ; K, 0.1 mg/L; Mg, 0.01 mg/L; Na, 0.06 mg/L; Cl, 0.12 mg/L; SO1, 0.34 mg/Ll.
Cu speciation was modeled using the computer program MINEQL+ (Schecher and McAvoy, 1991). Input data for water quality parameters and measured cations and anions were the mean values for each Cu exposure level. Chemical equilibrium constants used in model calculations were adopted from the MINEQL+ database, or from Sunda and Hanson (1979) for Cu-hydroxide and Cu-carbonate species.

STATISTICS
ANOVA and Dunnett's multiple comparison procedure

Key result

Duration:

60 d

Dose descriptor:

NOEC

Effect conc.:

2.2 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

not applicable

Conclusions:

Under the conditions of a long-term toxicity study on fish, the 60d-NOEC value for copper chloride was 2.2 μg/L.

Executive summary:

Rainbow trout fry were exposed in soft water to sublethal concentrations of copper for 60 days under controlled laboratory conditions. At 20-day intervals, fish were sampled for weight, length, and whole-body copper and metallothionein concentrations.

Under the conditions of a long-term toxicity study on fish, the 60d-NOEC value for copper chloride was 2.2 μg/L.

Reference 2

Endpoint:

long-term toxicity to fish, other

Type of information:

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

Adequacy of study:

weight of evidence

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 cyanide (CAS No. 544-92-3; target chemical) and copper chloride (CAS No. 7758-89-6; source chemical).

3. ANALOGUE APPROACH JUSTIFICATION
The registered substance is insoluble and has low degradability and low rate of decomposition into copper compounds and cyanides in water. However, when decomposed, the cyanide rapidly changes into hydrogen cyanide, which is not bioconcentrated. Therefore, it is considered that the harmfulness to the environment will have a greater influence on the copper compound. Therefore, since there is no long-term toxicity data on fish available for the registered substance copper cyanide, data on copper chloride were used.
Based on these elements and to the fact that both target and source chemicals are inorganic substances having close physical-chemical properties and environmental fate, it can be assumed that copper chloride and copper cyanide may have similar ecotoxicological properties. The read-across approach between copper cyanide and copper chloride is therefore relevant for this endpoint.

Reason / purpose for cross-reference:

read-across source

GLP compliance:

not specified

Key result

Duration:

60 d

Dose descriptor:

NOEC

Effect conc.:

2.2 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Conclusions:

Under the conditions of a long-term study to assess the toxicity of copper chloride on fish and based on a read-across approach, the 60d-NOEC value for the registered substance copper cyanide is considered to be 2.2 μg/L.

Executive summary:

Rainbow trout fry were exposed in soft water to sublethal concentrations of copper for 60 days under controlled laboratory conditions. At 20-day intervals, fish were sampled for weight, length, and whole-body copper and metallothionein concentrations.

Under the conditions of the long-term toxicity study on fish, the 60d-NOEC value for copper chloride was 2.2 μg/L.

A read-across has been performed between copper cyanide (CAS No. 544-92-3; target chemical) and copper chloride (CAS No. 7758-89-6; source chemical).

Indeed, the registered substance is insoluble and has low degradability and low rate of decomposition into copper compounds and cyanides in water. However, when decomposed, the cyanide rapidly changes into hydrogen cyanide, which is not bioconcentrated. Therefore, it is considered that the harmfulness to the environment will have a greater influence on the copper compound. Therefore, since there is no long-term toxicity data on fish available for the registered substance copper cyanide, data on copper chloride were used.

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

Therefore, under the conditions of a long-term study to assess the toxicity of copper chloride on fish and based on a read-across approach, the 60d-NOEC value for the registered substance copper cyanide is considered to be 2.2 μg/L.

Description of key information

Under the conditions of a long-term study to assess the toxicity of copper chloride on fish and based on a read-across approach, the 60d-NOEC value for the registered substance copper cyanide is considered to be 2.2 μg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

2.2 µg/L

Additional information

For that endpoint, a study on the registered substance was not available. Nevertheless, a study was available to assess the long-term toxicity of copper chloride on fish.

In this study, rainbow trout fry were exposed in soft water to sublethal concentrations of copper for 60 days under controlled laboratory conditions. At 20-day intervals, fish were sampled for weight, length, and whole-body copper and metallothionein concentrations. Under the conditions of this long-term toxicity study on fish, the 60d-NOEC value for copper chloride was 2.2 μg/L.

A read-across has been performed between copper cyanide (CAS No. 544-92-3; target chemical) and copper chloride (CAS No. 7758-89-6; source chemical).

Indeed, the registered substance is insoluble and has low degradability and low rate of decomposition into copper compounds and cyanides in water. However, when decomposed, the cyanide rapidly changes into hydrogen cyanide, which is not bioconcentrated. Therefore, it is considered that the harmfulness to the environment will have a greater influence on the copper compound. Therefore, since there is no long-term toxicity data on fish available for the registered substance copper cyanide, data on copper chloride were used.

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