Cadmium telluride

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Principles of method if other than guideline:

The composition of the medium is identical to the OECD medium as described in OECD 201 (2006) except for the concentrations of FeCl3 (1.60 instead of 1.2 mg/l) and MgSO4.7H20 (1487.4 instead of 300 mg/l). This slightly different medium is used for many years in the VITO lab. This has no further implication on the test results as growth parameters in controls are normal. For this test also Na2EDTA was omitted to prevent chelation of the dissolved metals. Organic matter was added instead. Growth parameters in controls were sufficient in this adapted medium.

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations:0- 0.7-1.4-2.2-4.9-9.6 mg CeTe/L
- Sampling method:
Chemical analyses was performed at the start and at the end of the experiments to document on the dissolved cadmium concentrations and stabilityduring the test

Vehicle:

no

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

NAME : Pseudokirchneriella subcapitata
CODE CCAP: 278/4 -Green micro algae. Phylum: Chlorophyta (Green Algae) Class: Chlorophyceae
Order: Not assigned
Genus: Pseudokirchneriell
Botanical name: - Pseudokirchneriella subcapitata (Korshikov).
Lab keeping and breeding: SOP TALGV001v3.
Batch used in these experiments: 02 03

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23°C

pH:

mean at end start and end of test:
blanks: 7.11 -7.13
control: 7.72-7.81
test1: 7.73-8.18
test2: 7.69-7.93
test3:7.70-7.86
test4:7.72-7.83
test5:7.72-7.83

Nominal and measured concentrations:

nominal concentrations (mg CdTe/L):
0-0.19-0.37-0.74-1.48-2.97

Details on test conditions:

Set up:
Abiotic control (3 replicates): to check for background biological growth
Blank (biotic) control (6 replicates): to establish the control growth parameters, needed for test validation (see validity criteria) and as a reference.
Test dilutions (3 replicates): to establish the inhibiting effect of the test substance when compared to controls.
Cell number at the start: Each recipient was inoculated with an equal number of algal cells at the beginning of the experiment, except for the 3 abiotic controls.
The number of cells in the inoculum suspensions were 7777 x 106 cells/ml
Test vessels: sterile glass erlenmeyers 500 ml, previously washed in a standard laboratory dishwasher and sterilized in the autoclave. During the test the vessels were covered with sterile cotton stoppers (air permeable).
Test volumes: 100 ml of each dilution or medium (control), 100 μl algae (not added to abiotic conditions).
Medium: EDTA free OECD Medium (SOP TALGV004v3; Batches 17/01/2012 and 12/03/2012) was used to provide the nutrients and minerals that are needed for unrestricted algal growth. Organic matter is added to the control/dilution medium and to the prepared DA solutions on sponsor’s request: organic matter isolate (with 53% carbon content, Aquatic NOM (sunawannee River – product 1R101N)) was obtained from the International Humic Substance Society and added to the solutions to provide 2mg C/l. Dilutions were prepared by mixing these MO supplied solutions.
Conditions: test vessels were placed in incubator BIO 0658 at random places (daily changing), continuous shaking (100 rpm), 23 °C, continuous light(3562 lux at ALGE 12 003 herhaling 2)

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CdTe

Basis for effect:

cell number

Remarks on result:

other: Dissolved Cd concentration was below DL

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.37 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CdTe

Basis for effect:

growth rate

Remarks on result:

other: Dissolved Cd concentration was below DL

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.74 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CdTe

Basis for effect:

growth rate

Remarks on result:

other: Dissolved Cd concentration was below DL

Reported statistics and error estimates:

The concentration effect curves for growth rate are presented. EC50 value was calculated using linear interpolation where possible.
Student t-test was used to evaluate statistic relevant differences when compared to controls (p<0.05).

Validity criteria fulfilled:

yes

Conclusions:

very good quality study considered useful for classification

Executive summary:

Tests done according to standard protocol. Good quality and considered useful for classification; whereby a EC50 of 3.1 mg CdTe/L was found.

Description of key information

The toxicity of CdTe on Pseudokirchnierella was derived using a DA solution.

The LC50 derived was 3.1 mg CdTe/L. This endpoint will be used for classification. However, as Cd2+ ion determines ecotoxicity, the PNEC deriviation will be based on the Cd 2+ ion as determined in the RA (ECB 2007).

Key value for chemical safety assessment

EC50 for freshwater algae:

3.1 mg/L

EC10 or NOEC for freshwater algae:

0.37 mg/L

Additional information

Two tests were performed using Pseudokirchneriella subcapitata as test species. However, high pH levels were noted in the algae 12 003 record (Vito 2012e). Therefore, the EC50 of the ALGE 12003 herhaling 2 (Vito 2012d) was used. A LC50 of 3.1 mg CdTe/L was determined.

As Cd2+ ion determines ecotoxicity, the PNEC deriviation will be based on the Cd 2+ ion as determined in the RA (ECB 2007).