Lead titanium trioxide

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline followed. Study well conducted. No data on the lead test-compound in the report, however verified by oral communications.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2007

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

Revised Test Guideline OECD No.201: Alga growth inhibition test. Organization for Economic Cooperation and Development, Paris, France. 2006

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Lead dichloride

EC Number:

231-845-5

EC Name:

Lead dichloride

Cas Number:

7758-95-4

Details on test material:

- Name of test material (as cited in study report): Pb, lead dichloride

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: samples for dissolved Pb (0.45µm) were taken from all treatments (at test initiation and termination)

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: P. subcapitata
- Source (laboratory, culture collection): Purchased from the Culture Collection of Algae and Protozoans (Argyl, UK).
- Number of cells at test initiation: 10000 cells/mL

Study design

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test conditions

Hardness:

between 24 - 263 mg/L CaCO3

Test temperature:

25 °C

pH:

between 6.73-7.86

Nominal and measured concentrations:

5 test concentrations and control
Mean dissolved measured Pb conc. in µg/L:
Synthetic pH 6.6 test: 0.2; 6.0; 12.2; 24; 44.3; 72.7; 134.5
Synthetic pH 7.2 test: 0.1; 2.6; 5.7; 11.3; 20.8; 39.1; 64.8
Synthetic pH 7.8 test: 0.2; 3.3; 5.6; 10.3; 19.1; 36.7; 64.6; 111.7
Natural Ankeveen test: 0.4; 48; 93.6; 176.7; 367.3; 581.1; 1042.9
Natural Regge test: 0.2; 8.8; 23.3; 82.5; 239.9; 461; 861.2
Synthetic FA 4 mg test: 0.4; 3.9; 6.7; 13.7; 31.1; 43.4; 78
Synthetic FA 20 mg test: 0.4; 19.3; 40.6; 67.5; 101.7; 192.3; 390.9

Details on test conditions:

TEST SYSTEM
- Initial cells density: 10exp.4 cells/ml
- No. of vessels per concentration (replicates):3

GROWTH MEDIUM
- Standard medium used: yes, Tests are conducted in standard OECD test medium or in natural waters to which nutrients were added

OTHER TEST CONDITIONS
- Adjustment of pH: pH was recorded daily and if it deviated by more than 0.2 pH units from 6.0 it was brought back to 6.0 by adding dilute HCl or NaOH.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]: Cell density was monitored daily using a Coulter Counter.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

8.8 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic pH 6.6 test; Hardness: 24 mg/L; pH: 6.73; confidence limits: 6.1-12.8 µg/L

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

5.4 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic pH 7.2 test; Hardness: 24 mg/L; pH: 7.28; confidence limits: 3.3-8.7 µg/L

Effect concentrations 3

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

23.4 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic pH 7.8 test; Hardness: 24 mg/L; pH: 7.71; confidence limits: 17.1-31.9 µg/L

Effect concentrations 4

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

93 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Natural Ankeveen water; Hardness: 174 mg/L; pH: 7.34; confidence limits: 65.4-132.2 µg/L

Effect concentrations 5

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

34.1 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Natural Regge water: Hardness: 263 mg/L; pH: 7.86; confidence limits: 26.8-43.4 µg/L

Effect concentrations 6

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

4.5 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic FA 4 mg water; Hardness: 24 mg/L; pH: 7.28; confidence limits: 3.7-5.5 µg/L

Effect concentrations 7

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

12 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic FA 20 mg test; Hardness: 24 mg/L; pH: 7.28; confidence limits: 7.9-18.4 µg/L

Effect concentrations 8

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

35.9 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic pH 6.6 test; Hardness: 24 mg/L; pH: 6.73; confidence limits: 30.9-41.8 µg/L

Effect concentrations 9

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

23.1 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic pH 7.2 test; Hardness: 24 mg/L; pH: 7.28; confidence limits: 19-28 µg/L

Effect concentrations 10

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

243.4 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic pH 7.8 test; Hardness: 24 mg/L; pH: 7.71; confidence limits: 199.3-297.2 µg/L

Effect concentrations 11

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

322.9 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Natural Ankeveen water; Hardness: 174 mg/L; pH: 7.34; confidence limits: 279.6-372.9 µg/L

Effect concentrations 12

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

233.1 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Natural Regge water: Hardness: 263 mg/L; pH: 7.86; confidence limits: 213.3-254.8 µg/L

Effect concentrations 13

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

21.7 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic FA 4 mg water; Hardness: 24 mg/L; pH: 7.28; confidence limits: 20.1-23.5 µg/L

Effect concentrations 14

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

65.2 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: Synthetic FA 20 mg test; Hardness: 24 mg/L; pH: 7.28; confidence limits: 54.8-77.5 µg/L

Details on results:

Validity criteria according to OECD:
Mean control µ/d were all > 1
Factor increase of cell density over 72 hours: between 7.7 and 16.4
Coefficient of variation of control µ (%) were all < 10%

Reported statistics and error estimates:

Growth rate (µ) was calculated according to OECD (2004) on the basis of the cell density measurements. At the end of test the EC10 and EC50 were calculated using the logistic concentration response equation. NOEC and LOEC were determined using a one-sided Dunnet test (p<0.05) testing whether a growth rate was significantly lower then in a control treatment. Bartlett's test was used to test for homogeneity of variances and the non-parametric Mann-Whitney U test was used when this criterion was not fulfilled. Effect concentrations are reported on the basis of measured dissolved Pb concentrations using the log-logistic curve fitting of the raw data.

Any other information on results incl. tables

Type water	pH	Hardness	EC10 (µg/L)	Confidence limits (µg/L)	EC50 (µg/L)	Confidence limits (µg/L)
Synthetic pH 6.6	6.73	24	8.8	6.1-12.8	35.9	30.9-41.8
Synthetic pH 7.2	7.28	24	5.4	3.3-8.7	23.1	19-28
Synthetic FA 4 mg water	7.28	24	4.5	3.7-5.5	21.7	20.1-23.5
Synthetic FA 20 mg water	7.28	24	12	7.9-18.4	65.2	54.8-77.5
Natural Ankeveen water	7.34	174	93	65.4-132.2	322.9	279.6-372.9
Synthetic pH 7.8	7.71	24	23.4	17.1-31.9	243.4	199.3-297.2
Natural Regge water	7.86	263	34.1	26.8-43.4	233.1	213.3-254.8

Applicant's summary and conclusion

Conclusions:

The toxicity of lead in fresh water algae significantly decreased due to a decrease of the bioavailability of the lead ion. Changing the hardness or concentrations of Na+, K+ or Mg2+ had no additional significant effect on toxicity expressed as the 96h-LC50 for C. dubia. The lowest and the highest 48h-LC50 differed by three orders of magnitude (range: 30 - 3100 µg/L).

Executive summary:

Standard 72 -hours chronic growth inhibition tests were conducted according to the draft revised OECD guideline No.201 (OECD,2004) with three algae species: Pseudokirchneriella subcapitata, Chlorella kesslerii, and Chlaydomonas reinhardtii. For all species, a control and at least five test concentrations were investigated in triplicate. Initial cell densities were 104 cells/ml for P. subcapitata and C. reinhardtii and 5x103 cells/ml for C. kesslerii. Cell density was monitored daily using a Coulter Counter for test P. subcapitata and C. kesslerii. Optical density measurements were used as a surrogate for cell density, using a relation between cell density and optical density. Growth rate (µ) was calculated according to OECD (2004) on the basis of the cell density measurements.

Samples for dissolved Pb (0.45µm) were taken from all treatments (at test initiation and termination) and were measured by flame-AAS (nominal concentrations>200µg/l) or ICP-MS (nominal conc. < 200 µg/l).

pH was recorded daily and if it deviated by more than 0.2 pH units from 6.0 it was brought back by adding dilute HCl or NaOH. DOC was measured prior to addition of MES and was always within 15% of the nominal value of 2.1mg/l. At the end of the test the EC10 and EC50 were calculated using the logistic concentration response equation. NOEC and LOEC were determined using a one-sided Dunnet test (p<0.05) testing whether a growth rate in a Pb treatment was significantly lower than in a control treatment. Bartlett's test was used to test for homogeneity of variances and the non-parametric Mann-Whitney U test was used when this criterion was not fulfilled. Effect concentrations are reported on the basis of measured dissolved Pb concentrations at test initiation. Reliable EC10 values for growth rate of 30 and 99 were estimated for respectively P. subcapitata and C. kesslerii. The dose response curve for the test with C. reinhardii was not clear and therefore the NOEC value 145 µg/l was not retained.