Cerium

Long-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

long-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:

from 21-DEC-2007 to 27-FEB-2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed according to an international test guideline and to GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Dicerium tricarbonate

EC Number:

208-655-6

EC Name:

Dicerium tricarbonate

Cas Number:

537-01-9

IUPAC Name:

dicerium tricarbonate

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations:
Triplicate samples were taken from the test media of all test concentrations (loading rate of 130 mg/L and dilutions 1:3.2, 1:10, 1:32 and 1:100) and from the control at the start of the first treatment period (Day 0), at a treatment period in the second week (Day 7), and at a treatment period in the last week (Day 16). The following samples were taken in triplicate at the end of two test medium renewal periods of 48 hours (Days 2 and 9) and at the end of one renewal period of 72 hours (Day 19):
a) Samples with food, taken from the actual test by combining the contents of the test beakers after the end of the treatment period.
b) Samples without food and test animals incubated during the renewal periods under the test conditions.
Two of the triplicate samples were sent to the analytical laboratory at ambient temperature. The remaining samples were stored at Harlan Laboratories Ltd. as insurance for possible sample losses (retain samples). The concentrations of cerium were measured in two of the triplicate test media samples from the highest test concentration (loading rate of 130 mg/L) which was determined to be the 21-day NOELR.
- Sampling method: data not available
- Sample storage conditions before analysis: immediately after sampling, the samples were acidified with 10% (v/v) nitric acid (HNO3, 65% Suprapur, Merck) to stabilize the samples during storage. Then the samples were stored in PE flasks at ambient temperature and protected from light until analysis.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method:
Due to the low water solubility of the test item, a saturated solution of the test item with the loading rate of 130 mg/L (corresponding to the loading rate of 100 mg/L when corrected for the water content of the test item) was tested as the highest test concentration and was used as a stock solution for preparation of the test media of lower test concentrations (dilutions 1:3.2, 1:10, 1:32 and 1:100). Additionally, a control (test water without test item) was tested in parallel.
The test method is based on the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures.
Seven days before the start of the test and seven days prior to each test medium renewal, a dispersion of the test item with the loading rate of 130 mg/L was prepared by dispersing 260 mg (effective weights: 260.0-260.7 mg) of the test item in 2000 mL of test water. The test item was mixed into the test water as homogeneously as possible using ultrasonic treatment for 15 minutes and intense stirring. No auxiliary solvent or emulsifier was used. The dispersions were stirred on magnetic stirrers at room temperature in the dark over six days. Then, the stirrers were switched off in order to allow the non-dissolved test item to deposit at the bottom of the stirring vessel. The contact time of the test item and the test water for equilibration
(i.e. stirring time and deposition period) was 7 days.
The equilibrated test medium (saturated solution) was carefully separated from the non-dissolved test item. The saturated solution was used as the highest test concentration. Additionally, adequate volumes of the saturated solution were diluted with test water for the preparation of the test media with lower test item concentrations.
- Eluate: no
- Differential loading: yes
- Controls: test water without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc): yes, on the bottom of the stirring vessel, but not in the final test solution

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: clone defined as clone 5
- Source: supplied in 1992 by University of Sheffield/UK
- Age of parental stock (mean and range, SD): < 24 hours. These daphnids originated from parental daphnids that were at least 14 days old but no older than 4 weeks, and were not first brood progeny.
- Feeding during test
- Food type: a food mixture containing a suspension of green algae of the species Scenedesmus subspicatus (freshly grown in the Harlan laboratories) and a fish food suspension.
- Amount:
The carbon contents of the algal and fish food suspensions were determined using a Shimadzu TOC 5000A Analyzer. The food amounts were based on the measured concentrations of total organic carbon (TOC) in the food suspensions and consisted of 50% algae and 50% fish food
(based on TOC). The amounts of TOC fed per test animal and day were as follows:
Day 0-4: 0.10 mg TOC / Daphnia
Day 5-13: 0.15 mg TOC / Daphnia
Day 14-20: 0.20 mg TOC / Daphnia
- Frequency: daily


ACCLIMATION
- Acclimation period: no

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

none

Test conditions

Hardness:

2.5 mmol/L (= 250 mg/L as CaCO3)

Test temperature:

19-20°C

pH:

between 7.7 to 8.0

Dissolved oxygen:

at least 8.0 mg/L

Salinity:

not applicable

Nominal and measured concentrations:

loading rate of 130 mg/L (corresponding to the loading rate of 100 mg/L when corrected for the water content of the test item) and dilutions 1:3.2, 1:10, 1:32 and 1:100

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type : 100 mL glass beakers covered with glass plates to reduce the loss of water by evaporation and to avoid the entry of dust into the solutions
- Material, size, headspace, fill volume: vessels containing 80 mL of test medium
- Aeration: no data
- Type of flow-through (e.g. peristaltic or proportional diluter): none (semi-static test)
- Renewal rate of test solution (frequency/flow rate): three times per week
- No. of organisms per vessel: Each test animal was kept individually in test vessel
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10
- Biomass loading rate: no data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted test water : analytical grade salts dissolved in purified water
- Alkalinity: 0.9 mmol/L
- Ca/Mg ratio (mol): no data
- Culture medium different from test medium: no
- Intervals of water quality measurement: At the beginning and end of each test medium renewal period, the pH and dissolved oxygen concentrations were measured in one replicate of each test concentration and the control. At the same time, the water temperature was measured in one of the control replicates. Additionally, the room temperature was continuously monitored. The appearance of the test media was recorded at the beginning and end of each test medium renewal period.
- No further data

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: a 16 hour light to 8 hour dark with a 30 minute transition period.
- Light intensity: between 500 and 630 lux

EFFECT PARAMETERS MEASURED :
Each working day, the test replicates were observed for mortality of the parental daphnids and the presence of juveniles. The offspring were counted and removed three times per week at the renewal of the test media. At the same dates, the test beakers were also checked for the presence of aborted eggs or dead offspring.
The reproduction rate was calculated as the total number of living offspring produced per parent female surviving until the end of the test.
The mean reproduction rates of the daphnids at the test concentrations were compared to the control by multiple Williams’ tests. No EL values for the inhibition of the reproduction rate could be calculated since no effect was determined on the reproduction of the daphnids up to the highest concentration tested.

RANGE-FINDING STUDY
Test concentrations / Results used to determine the conditions for the definitive study: The choice of the test concentrations was based on the results of the acute toxicity test with Daphnia magna (RCC Study Number A16391). Concentrations of the test item far above the water solubility or loading rates above 130 mg/L (corresponding to the loading rate of 100 mg/L when corrected for the water content of the test item) were not tested in accordance with the test guidelines.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

21 d

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: active ingredient corrected for its water content

Basis for effect:

other: survival and reproduction

Effect concentrations 2

Duration:

21 d

Dose descriptor:

LOELR

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: active ingredient corrected for its water content

Basis for effect:

other: survival and reproduction

Details on results:

Analytical Results :
The concentration of cerium was measured in the test medium of the highest test concentration (saturated solution with the loading rate of 130 mg/L, corresponding to the loading rate of 100 mg/L when corrected for the water content of the test item). The samples were taken from the test medium without food at the start and the end of three test medium renewal periods. In addition, samples were taken from the aged test medium of the actual test (containing food).
The saturated solution used as test medium was prepared by sedimentation of the undissolved test item until the supernatant appeared to be a clear solution (24 hours). The test medium was not filtered on the request of the Sponsor. The wide range of measured concentrations of the test item was considered to be caused by very fine particles of the test item which were obviously still present in the supernatant after the deposition period. Thus, the test medium contained the maximum concentration of dissolved test item and very fine undissolved test item particles. The following concentrations were measured during the test:
Sampling Day Age and type of medium Measured concentration of cerium (mg/L) Corresponding concentration of test item (mg/L)*
Day 0 0 hours, without food 14 30
Day 2 48 hours, without food 0.014 0.030
Day 2 48 hours, with food 0.11 0.23
Day 7 0 hours, without food 0.37 0.79
Day 9 48 hours, without food 0.22 0.47
Day 9 48 hours, with food 0.20 0.43
Day 16 0 hours, without food 0.21 0.45
Day 19 72 hours, without food 0.005 0.011
Day 19 72 hours, with food 0.096 0.21

*: based on a cerium content of the test item of 46.7%

The biological results were based on the loading rate of the test item of 130 mg/L.

Biological results:
In the control and at all test concentrations up to and including the loading rate of 130 mg/L, the survival of the test animals was at least 80% or higher at the end of the test. Thus, the survival of Daphnia magna over 21 days was not affected by the test item up to and including the highest test concentration (loading rate of 130 mg/L).

The first young offspring released from their parent animals were recorded in the control and at all test concentrations at observation on Day 8. Thus, the time of the first brood was not affected by the test item up to and including the loading rate of 130 mg/L. The mean reproduction rate of the daphnids in the control was 115.1 ± 16.7 living offspring per adult (mean ± standard deviation). The mean reproduction rates of the exposed daphnids were between 86 and 97% of the reproduction in the control and no concentration-effect relationship was determined. No significant inhibitory effect of the test item on the mean reproduction rate was determined up to and including the highest test concentration (Williams’ test, one-sided,
alpha = 0.05).
No visible abnormalities were observed in the test animals during the test.

General results:
No remarkable observations were made concerning the appearance of the test media. All test media were clear throughout the test
medium renewal periods.

Results with reference substance (positive control):

none

Reported statistics and error estimates:

The mean reproduction rates of the daphnids at the test concentrations were compared to the control by multiple Williams'test.

Any other information on results incl. tables

 

Number of surviving test animals :

Exposure day	Treatment / Dilution
	Control	Dilution 1:100	Dilution 1:32	Dilution 1:10	Dilution 1:3.2	Saturated Solution (loading rate 130 mg/L)
0 1 2 5 6 7 8 9 12 13 14 15 16 19 20 21	10 10 10 10 10 10 10 10 10 10 10 8 8 8 8 8	10 10 10 10 10 10 10 10 9 9 9 9 9 8 8 8	10 10 10 10 10 10 10 10 8 8 8 8 8 8 8 8	10 10 10 10 10 10 10 10 9 9 9 9 9 9 9 9	10 10 10 10 10 10 10 10 8 8 8 8 8 8 8 8	10 10 10 10 10 10 10 10 9 9 9 9 9 9 9 8
% surviving on Day 21	80	80	80	90	80	80

 

 

Total number of living young daphnids produced by all adults (cumulative values):

Exposure day	Treatment / Dilution
	Control	Dilution 1:100	Dilution 1:32	Dilution 1:10	Dilution 1:3.2	Saturated Solution (loading rate 130 mg/L)
0 1 2 5 6 7 8 9 12 13 14 15 16 19 20 21	0 0 0 0 0 0 177 177 469 469 629 660 695 864 864 1020	0 0 0 0 0 0 174 174 444 444 560 588 626 744 744 847	0 0 0 0 0 0 120 175 437 437 541 640 643 787 787 921	0 0 0 0 0 0 120 151 418 418 596 596 596 733 733 965	0 0 0 0 0 0 176 176 457 457 612 612 612 700 700 883	0 0 0 0 0 0 156 156 373 373 476 529 542 720 720 889
% of control^1	100.0	83.0	90.3	94.6	86.6	87.2

 

¹: based on the value of the last exposure day

 

Number of living offspring produced per surviving adult after 21 days of exposure:

Replicate N°.	Treatment / Dilution
	Control	Dilution 1:100	Dilution 1:32	Dilution 1:10	Dilution 1:3.2	Saturated Solution (loading rate 130 mg/L)
1 2 3 4 5 6 7 8 9 10	136 * 140 * 136 124 118 109 24 134	* 138 44 103 * 142 106 45 79 136	106 131 101 66 * 119 134 * 119 119	46 139 87 126 149 145 32 97 * 135	127 * 70 25 137 47 126 140 * 135	19 101 73 109 138 * * 137 133 136
Mean SD n	115.1 38.2 8	99.1 39.9 8	111.9 21.6 8	106.2 43.6 9	100.9 46.2 8	105.8 41.9 8
CV %	33.3	40.3	19.3	41.1	45.8	39.6
% of control	100.0	86.1	97.2	92.3	87.6	91.9
STAT	-	n.s.	n.s.	n.s.	n.s.	n.s.

 

SD: standard deviation

n: number of replicates (surviving adults)

CV %: coefficient of variation in %: (SDx/meanx)⋅100%

*: test animal died during the test period

STAT: results of a Williams’ test with the mean values of living offspring

(one-sided, alpha = 0.05)

n.s.: mean value not significantly lower than in the control

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Control's survival rate = 80%, and control's mean reproduction rate > 60

Conclusions:

The test item dicerium tricarbonate had no toxic effect on survival and reproduction of Daphnia magna after the exposure period of 21 days up to the loading rate of 130 mg/L. Thus, the NOELR of the test item was determined to be at least the loading rate of 130 mg/L (100 mg/L, when corrected for the water content of the test item). The LOELR was above the loading rate of 130 mg/L.

Executive summary:

The effect of the test item, dicerium tricarbonate, on the survival and reproduction of Daphnia magna was investigated in a semi-static test over 21 days following the OECD Guidelines for Testing of Chemicals, No. 211 (1998) and the EU Commission Directive 92/69/EEC, C.20 (2001). Daphnids were exposed to control, and test chemical at nominal concentration of 130 mg of dry substance /L (loading rate) and the dilutions 1:3.2, 1:10, 1:32 and 1:100 of the saturated solution. The mortality and reproduction of the daphnids were compared with the corresponding parameters in the control and symptoms of toxicity were recorded.

 

The test item, dicerium tricarbonate, had no toxic effect on survival and reproduction of Daphnia magna after the exposure period of 21 days up to the loading rate of 130 mg/L. Thus, the NOELR of the test item was determined to be at least the loading rate of 130 mg/L (100 mg/L, when corrected for the water content of the test item). The LOELR was above the loading rate of 130 mg/L.

 

This study is classified as acceptable and satisfies the guideline requirements for a chronic toxicity study with freshwater invertebrates.