Cadmium telluride

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

ISO 11267 (Inhibition of Reproduction of Collembola by Soil Pollutants)

Qualifier:

according to guideline

Guideline:

other: OECD guideline No 232

GLP compliance:

yes

Application method:

contact

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Folsomia candida

Animal group:

Collembola (soil-dwelling springtail)

Details on test organisms:

Species: Folsomia candida (Willem)
Source:Combined limit/range-finding test: In-house laboratory culture with known history.
Final test: Faculty of Earth and Life Sciences (Animal Ecology), VU University Amsterdam, The Netherlands.
Reason for selection:This system has been selected as an internationally accepted species.
Characteristics:For the test, synchronous, 10 to 13-day old juvenile springtails were used.
Start of each batch: Adult springtails were placed in small containers with plaster of Paris base. Batches were split up in case of overcrowding. Springtails were transferred to fresh medium regularly. Breeding medium was humidified regularly with RO-water.
Composition of culture medium:Mixture of plaster of Paris (Knauf B.V., Utrecht, The Netherlands) and activated charcoal (Sigma Aldrich, The Netherlands). Plaster of Paris provides highly moist substrate, while the charcoal adsorbs waste gases and excretion products.
Temperature:20 ± 1°C
Feeding: Twice a week with dry yeast (Dr.Oetker).
Light: 16 hours photoperiod daily; 400-800 lux.
Test duration: 28 days

Study type:

laboratory study

Limit test:

no

Total exposure duration:

28 d

Test temperature:

20°C +-1 with a range of 20 +- 2°C

pH (if soil or dung study):

Parameter Day 0 Day 28
pH
Control 8.0 8.2
10 mg/kg d.s. 7.8 8.3
32 mg/kg d.s. 8.0 8.3
100 mg/kg d.s.8.0 8.3
320 mg/kg d.s.8.0 8.4
1000 mg/kg d.s.8.0 8.4

Humidity:

Parameter Day 0 Day 28
Control 47 46
10 mg/kg d.s. 45 45
32 mg/kg d.s. 46 46
100 mg/kg d.s.46 46
320 mg/kg d.s.45 44
1000 mg/kg d.s.44 44

Photoperiod and lighting:

Parameter Day 0 Day 28
Light intensity (lux) 560 529

Details on test conditions:

Test vessels: Volume: approximately 100 ml glass jar, covered with a plastic lid.
Synchronization of a batch: 25 days prior to the test adult springtails were placed in small containers with plaster of Paris base and allowed to lay eggs over a two-day period. After this time adults were removed. Thirteen days after the first juveniles emerge from the eggs they were used for the test.
Artificial soil: According to the guideline. Weight of components based on dry mass:
5% sphagnum peat, no visible plant remains, finely ground (Lentse Potgrond, Lent, The Netherlands);
20% kaolin clay (China Clay Ast, source Silex Pottenbakkersmaterialen, ‘s-Hertogenbosch, The Netherlands);
~74% industrial sand, >50% of particles between 50 and 200 microns (Zilverzand M32, source Eurogrit B.V., Nieuwegein, The Netherlands);
<1.0% calcium carbonate (analytical grade, Merck KGaA, Darmstadt, Germany) to obtain an initial pH of 6.0 ± 0.5;
The dry constituents are mixed thoroughly before addition of the test substance.
Number of replicates: 8 for the control, 4 for each test concentration.
Loading: 10 springtails per vessel (containing approximately 30 g of wet soil).
Temperature: 20 ± 1°C with a temperature range of 20 ± 2°C.
pH: 6.0 ± 0.5
Aeration: Twice a week by briefly opening the lid.
Light: 16 hours photoperiod daily, intensity 400 - 800 lux.
Feeding: Weekly with approx. 2 mg dry yeast (Dr. Oetker).
On day 14 test vessels were weighted in order to check for loss of moisture. If the difference in weight between day 0 and day 14 was higher than 2% an appropriate amount of Mili-RO water was added.
After preparation of the test media springtails were tapped from the breeding containers and introduced in the test containers

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CdTe

Basis for effect:

mortality

Remarks:

adults

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

11 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CdTe

Basis for effect:

reproduction

Remarks on result:

other: CI = 0.63-205

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CdTe

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CdTe

Basis for effect:

mortality

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

10 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

CdTe

Basis for effect:

reproduction

Reported statistics and error estimates:

When the difference in the number of young springtails was smaller than 20% then an average was calculated and the integer number was used forfurther analyses. Otherwise, additional counting was performed by these two persons at the same time and the results was taken for further analysis.
For the final test springtails were counted by one person. As no significant mortality (>20%) was observed in any of the concentrations tested, nostatistical analysis was performed. The EC10 and EC50 for reproduction was based on log-linear regression analysis of the percentages of reproduction inhibition versus the logarithms of the corresponding nominal exposure concentrations of the test substance.
For determination of the NOEC data of the limit concentration was statistically compared with data from the control treatment (Bonfferoni t-test) after checking for normality and homogeneity of variation (TOXSTAT Release 3.5, 1996, D.D. Gulley, A.M. Boelter, H.L. Bergman).

Total mortality of adult springtails observed in the control treatment was 5%. Mortality obseved in test groups ranged from 2.5 to 10% and was considered biologically not significant. Moreover, the observed mortality was not related to the dose applied.

Mean mortality in the final test

CdTe (mg/kg dw)	replicate number of springtails day 0	number of adult springtails day 28	moratlity day 28	mortality day 28 (%)	mortality (group mean) day 28 (%)
control	A	10	8	2	20
control	B	10	10	0	0
control	C	10	10	0	0
Control	D	10	10	0	0
control	E	10	10	0	0
Control	F	10	10	0	0
control	G	10	10	0	0
Control	H	10	8	2	20
10	A	10	10	0	0
10	B	10	9	1	10
10	C	10	10	0	0
10	D	10	9	1	10
32	A	11	11	0	0
32	B	10	9	1	10
32	C	10	8	2	20
32	D	10	10	0	0
100	A	10	9	1	10
100	B	10	10	0	0
100	C	10	10	0	0
100	D	10	10	0	0
320	A	10	8	2	20
320	B	10	8	2	20
320	C	10	10	0	0
320	D	10	10	0	0
1000	A	10	10	0	0
1000	B	10	10	0	0
1000	C	10	10	0	0
1000	D	10	9	1	0

On average 844 instars per replicate were found in the control. The coefficient of variation was 12%. Effects on reproduction ranged from 10 to 40% reduction and were related to applied doses at 10 through 320 mg/kg dw. The effects observed at 10,100 and 100 mg/kg dw were in agreement with the results of the combined limit/range finding test. Note that the effect observed at the highest concentration was lower than one observed 32 mg/kg dw and it was statistically not different from the control. For the worst-case scenario NOEC was set to 10 mg/kg dw. In the view of the fact that the EC10 for reproduction was 11 mg/kg dw the NOEC of 10 mg/kg dw seems to be a good estimate.

CdTe concentration (mg/kg dw)	replicate	number of instars (reproduction) day 28	reduction in reproduction (%)	group mean reduction in reproduction (%)
control	A	911
control	B	1004
control	C	696
control	D	888
control	E	878
control	F	728
control	G	876
control	H	768
10	A	602	29	10
10	B	828	1.9
10	C	876	-3.8
10	D	747	11
32	A	728	14	19*
32	B	625	26
32	C	630	25
32	D	744	12
100	A	512	39	25 *
100	B	735	13
100	C	690	18
100	D	585	31
320	A	588	30	40*
320	B	532	37
320	C	521	38
320	D	393	53
1000	A	597	29	14
1000	B	670	21
1000	C	884	-4.8
1000	D	751	11

* statistically signficant (p<0.01)

Validity criteria fulfilled:

yes

Conclusions:

Test done according standard protocol.

Executive summary:

Under the conditions of the study CdTe had no effect on reproduction of adult springtails (Folsomia candida) at 10 mg/kg dw (NOEC). The NOEC for mortality was 1000 mg/kg dw. The LC50 for mortality of adult springtails was beyond the range tested, i.e. exceeded 1000 mg/kg dw. The EC10 for reproduction was 11 mg/kg dw with a 95% CI between 0.63 -205 mg/kg dw. The EC50 for reproduction was beyond the range tested, ie exceeded 1000 mg/kg dw.

Description of key information

An ecotoxicity study was performed using Folsomia candida as test species.

No effects were seen up to a concentration of 10 mg CdTe/kg DW.
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

Short-term EC50 or LC50 for soil dwelling arthropods:

1 000 mg/kg soil dw

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:

10 mg/kg soil dw

Additional information

Under the conditions of the study CdTe had no effect on reproduction of adult springtails (Folsomia candida) at 10 mg/kg dw (NOEC). The NOEC for mortality was 1000 mg/kg dw. The LC50 for mortality of adult springtails was beyond the range tested, i.e. exceeded 1000 mg/kg dw. The EC10 for reproduction was 11 mg/kg dw with a 95% CI between 0.63 -205 mg/kg dw. The EC50 for reproduction was beyond the range tested, ie exceeded 1000 mg/kg dw.

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