Copper hydroxide nitrate (Cu2(OH)3(NO3))

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Study period:

1992

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference 1

Reference Type:

secondary source

Title:

Unnamed

Year:

1993

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: U.S. EPA Standard Methods

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Copper dinitrate

EC Number:

221-838-5

EC Name:

Copper dinitrate

Cas Number:

3251-23-8

Molecular formula:

Cu.2HNO3

IUPAC Name:

copper nitrate

Details on test material:

formula: Cu(NO3)2.3H2O

Sampling and analysis

Details on sampling:

Tests were conducted in very hard reconstructed water(VHRW; hardness 280-300 mg/L as CaCO3; alkalinity 225-245 mg/L as CaCO3). Chemical stock solutions were prepared in Millipore (Mill-Q Corp., Bedford, MA) water.
Stock and dilution water solutions were arjusted to the desired pH (6.25 and 7.5, with 8.25 remaining unadjusted) using analytical-grade HCl.
Test concentrations were prepared using a 50% dilution series with VHRW also adjusted to the target pH. Duplicate 30-mL aliquots at each concentrationwere dispensed into 30-ml polypropylene cups and sealed with 35-mm polystyrene culture dish bottoms as lids to prevent headspace gas exchange and thus provide pH control for tests conducted at pH values 6.25 and 7.25. The tests conducted at 8.25 were left unsealed, as the ambiant pH of VHRW is 8.25 to 8.5.

Test organisms

Test organisms (species):

Ceriodaphnia dubia

Details on test organisms:

Test organisms were cultured at the U.S. Environmental Protection Agency (EPA) laboratory in Duluth, Minnesota. Age of organisms at time of testion was <= 48 hours.

Study design

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

280-300 mg/L as CaCO3

Test temperature:

25°C

pH:

6.25 - 7.25 and 8.25

Dissolved oxygen:

Dissolved oxygen was measuread at test termination and was never below 5 mg/L (60% saturation).

Salinity:

Alkalinity was 225-245 mg/L as CaCO3

Details on test conditions:

All tests were conducted in duplicate or triplicate, using five organisms per replicate at a constant temperature (25°C) and photoperiod (16:8 h lght:dark).

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

200 other: µg Cu/L at pH = 8.25

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

mortality

Remarks on result:

other: 150-270

Effect concentrations 2

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

28 other: µg Cu/L at pH = 7.25

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

mortality

Remarks on result:

other: 19-41

Effect concentrations 3

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

9.5 other: µg Cu/L at pH = 6.25

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

mortality

Remarks on result:

other: 7.0-13

Details on results:

Copper toxicity was greater at the lowest than at the highest pH. These results are supported by both theoretical and empirical studies. Campbell and Stokes (Acidification and toxicity of metals to aquatic biota - 1985) predicted total Copper to be more toxic at lower pH due to the greater concentration of free ions available to cause Copper toxicity at the cellular level, combined with the decreased effect of Copper ions at lower pH. Toxicity tests conducted with ceriodaphnia and bioaccumulation studies also indicated increase bioavailability at lower pH values. The high susceptibility of Copper to complexation by inorganic and organic ligands may be a more determinative factor than pH in predicting the toxicity of Copper.
Since Copper nitrate is more water soluble than Copper hydroxide nitrate, test provides a conservative estimate of the acute aquatic toxicity of Basic Copper Nitrate.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the test, the 48-hour LC50 value for Copper, using Ceriodaphnia dubia, was 200 µg Cu/L. Based on a content of 53% Copper in Basic Copper Nitrate, the 48-hour LC50 value for this substance is estimated to be 377 µg/L.