Amorphous condensation products of orthophosphoric acid and sodium carbonate (3-6 : 1)

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

August 1, 2007-August 31, 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The concentration of test substance in the test solution was analyzed at the beginning (0hr) and at the end (72hrs) of the study. Samples at 72hours were centrifuged slightly (5000rpm, 10min) to remove grown algae.

Details on test solutions:

Dilution water: OECD nutrient medium

Preparation of the test solutions: After 116mg of the test substance was added in a 1000ml beaker, and the dilution water was added up the mark of the beaker. This solution was then stirred for about 30 minutes. Serial dilution water prepared with dilution water to give the desired of exposure levels which were nominally 6.3, 12.5, 25, and 50 mg/L. For the control group, only the OECD culture medium was used.

Test organisms (species):

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

Details on test organisms:

Name
Pseudokirchneri ella subcapitata (Strain No. UTEX 1648)

Source
Division of Non-clinical Studies, Korea Institute of Toxicology (KIT), Korea Research Institute of Chemical Technology (KRICT), Daejeon, Korea, originally purchased from UTEX (The Culture Collection of Algae, The University of Texas at Austin , USA) on August, 2006 .

Pre-culture
Two to four days before the test, sterile OECD nutrient medium (OECD, 2006) was inoculated about 5.0 x 103 cells/mL cells/mL from a stock culture and incubated in a shaking incubator under continuous illumination (shaking rate: about 100 times/min, and light intensi ty: 60-120 µE/m2/s) at 21-24 °C to give an algal suspension in log phase growth.

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

24.0±0.2 °C

pH:

3.40-8.48

Nominal and measured concentrations:

- Nominal test concentration (mg/L): Control, 6.3, 12.5, 25.0, 50.0, 100.0
- Mean measured test concentration (mg/L): Control, 7.5, 14.5, 29.8, 56.7, 109.6

Details on test conditions:

Light intensity: 86-87 µE/m2/s
Inoculation
The test was started (0 hour) by inoculating 5.1 x 103 cells/mL in 250 mL conical flasks each containing 100 mL of test solution under sterile conditions. These cells were taken from an exponentially growing pre-culture under the same conditions as for the test.

Culture conditions
The inoculated flasks were then placed in a shaking incubator (DAIHAN Scientific, Korea). The cultures were incubated, without media renewal, for 72 hours under continuous illumination. The gaseous exchange and suspension of the algal cells were ensured by the action of the orbital shaker oscillating at 100 cycles per minute

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

37.7 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

49.2 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

77.9 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 7.5 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

7.5 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

5.8 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

10.9 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

32 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 7.5 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

7.5 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Details on results:

All test and control cultures were inspected microscopically at 72 hours. No abnormalities were detected in any of the cultures and there was no sign of contamination by foreign algal cells or protozoa .

Reported statistics and error estimates:

The result was analyzed using a TOXCALC Version 5.0.12 (Tidepool Scientific Software, USA). Assumption of homogeneity of variance was tested using Shapiro-Wilk' s test, while assumption of normality were tested with the Bartlett's test. Maximum Likelihood-Logit methods were applied to obtain the effective concentrations, EC 10 (and/or EC20) and EC5o for each approach. NOEC (No observed effect concentration) and LOEC (Lowest observed effect concentration) were analyzed by Dwmett's test (P<0.05).

Validity criteria fulfilled:

yes

Conclusions:

The 72hr-EC50 values (95% confidence limits) expressed in terms of the mean measured concentration of phosphoric acid (CAS No. 7664-38-2) to Pseudokirchneriella subcapitata (Strain No . UTEX 1648) were determined as 77.9 mg/L (66.2-92.8 rng/L) for average growth rate, and 32.0 mg/L (21.3-48.6 mg/L) for yield, respectively.

Executive summary:

The study was performed to assess the inhibition effect of phosphoric acid (CAS No. 7664 -38 -2) on the growth of the unicellular green alga, Pseudokircheriella subcapitata (Strain No. UTEX 1648).

The study was conducted in accordance with the OECD Guidelines for the Testing of Chemicals No. 201  Freshwater Alga and Cyanobacteria, GrowthInhibition Test (Adopted: March 23, 2006) .

The Toxicity rest was performed with control and nominal concentrations of 6.3, 12.5, 25.0, 50.0 and 100.0 mg/L each in triplicates, with mean measured concentrations of 7.5, 14.5, 29.8, 56.7 and 109.6 mg/L, respectively. Cultures were incubated on a shaking incubator under continuous illumination at 24.0 +/- 0.2 oC for 72 hours. Growth was monitored daily by determining the cell density of each culture by direct counts using a BECKMAN COULTERTM Multisizer 3 particle analyzer.

The following values, expressed in terms of the mean measured concentrations, were obtained from the test.

(Unit: mg/L, mean measured test concentration)

Estimates of Toxicity	Calculation Method
	Average Growth Rate	Yield
72-hr EC10 (95% confidence limits)	37.7 (21.9-48.1)	5.8 (1.1-10.9)
72-hr EC20  (95% confidence limits)	49.2 (34.1-59.2)	10.9 (3.5-17.3)
72-hr EC50  (95% confidence limits)	77.9 (66.2-92.8)	32.0 (21.3-48.6)
No  Observed Effect Concentration(NOEC)	< 7.5	<7.5
Lowest Observed Effect Concentration(LOEC)	7.5	7.5

All results were expressed in terms of the mean measured concentration (geometric mean). At 0 -hour (the start of the test), the mean measured concentrations were 7.5, 14.6, 29.9, 57.4 and 110.6 mg/L (110.6 -119.6% of the nominal concentration). The mean concentrations measured at 72 -hour (the end of the test) were 7.6, 14.5, 29.8, 56.0 and 108.7 mg/L (108.7 -120.6 % of the nominal concentration).

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This read-across is based on the hypothesis that source and target substances have similar properties because of structural similarity and that the target chemical (Amorphous condensation products of orthophosphoric acid and sodium carbonate (3-6 : 1)) hydrolyse to orthophosphoric acid and the sodium dihydrogen phosphate. The sodium dihydrogen phosphate has no identified hazardous properties. The orthophosphoric acid is source substance and is identical to the hydrolysis product of constituent A (metaphosphoric acid) of the target substance.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The concentration of test substance in the test solution was analyzed at the beginning (0hr) and at the end (72hrs) of the study. Samples at 72hours were centrifuged slightly (5000rpm, 10min) to remove grown algae.

Details on test solutions:

Dilution water: OECD nutrient medium

Preparation of the test solutions: After 116mg of the test substance was added in a 1000ml beaker, and the dilution water was added up the mark of the beaker. This solution was then stirred for about 30 minutes. Serial dilution water prepared with dilution water to give the desired of exposure levels which were nominally 6.3, 12.5, 25, and 50 mg/L. For the control group, only the OECD culture medium was used.

Test organisms (species):

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

Details on test organisms:

Name
Pseudokirchneri ella subcapitata (Strain No. UTEX 1648)

Source
Division of Non-clinical Studies, Korea Institute of Toxicology (KIT), Korea Research Institute of Chemical Technology (KRICT), Daejeon, Korea, originally purchased from UTEX (The Culture Collection of Algae, The University of Texas at Austin , USA) on August, 2006 .

Pre-cultu re
Two to four days before the test, sterile OECD nutrient medium (OECD, 2006) was inoculated about 5.0x 103 cells/mL from a stock culture and incubated in a shaking incubator under continuous illumination (shaking rate: about 100 times/min, and light intensi ty: 60-120 µE/m2/s) at 21-24 °C to give an algal suspension in log phase growth.

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

24.0±0.2 °C

pH:

3.40-8.48

Nominal and measured concentrations:

- Nominal test concentration (mg/L): Control, 6.3, 12.5, 25.0, 50.0, 100.0
- Mean measured test concentration (mg/L): Control, 7.5, 14.5, 29.8, 56.7, 109.6

Details on test conditions:

Light intensity: 86-87 µE/m2/s
Inoculation
The test was started (0 hour) by inoculating 5.1 x 103 cells/mL in 250 mL conical flasks each containing 100 mL of test solution under sterile conditions. These cells were taken from an exponentially growing pre-culture under the same conditions as for the test.

Culture conditions
The inoculated flasks were then placed in a shaking incubator (DAIHAN Scientific, Korea). The cultures were incubated, without media renewal, for 72 hours under continuous illumination. The gaseous exchange and suspension of the algal cells were ensured by the action of the orbital shaker oscillating at 100 cycles per minute

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

37.7 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

49.2 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

77.9 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 7.5 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

7.5 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

5.8 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

10.9 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

32 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 7.5 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

7.5 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

biomass

Details on results:

All test and control cultures were inspected microscopically at 72 hours. No abnormalities were detected in any of the cultures and there was no sign of contamination by foreign algal cells or protozoa .

Reported statistics and error estimates:

The result was analyzed using a TOXCALC Version 5.0.12 (Tidepool Scientific Software, USA). Assumption of homogeneity of variance was tested using Shapiro-Wilk' s test, while assumption of normality were tested with the Bartlett's test. Maximum Likelihood-Logit methods were applied to obtain the effective concentrations, EC 10 (and/or EC20) and EC5o for each approach. NOEC (No observed effect concentration) and LOEC (Lowest observed effect concentration) were analyzed by Dwmett's test (P<0.05).

Validity criteria fulfilled:

yes

Conclusions:

The read-across 72hr-EC50 values (95% confidence limits) expressed in terms of the mean measured concentration of phosphoric acid (CAS No. 7664-38-2) to Pseudokirchneriella subcapitata (Strain No . UTEX 1648) were determined as 77.9 mg/L (66.2-92.8 rng/L) for average growth rate, and 32.0 mg/L (21.3-48.6 mg/L) for yield, respectively.

Executive summary:

The study was performed to assess the inhibition effect of phosphoric acid (CAS No. 7664 -38 -2) on the growth of the unicellular green alga, Pseudokircheriella subcapitata (Strain No. UTEX 1648).

The study was conducted in accordance with the OECD Guidelines for the Testing of Chemicals No. 201  Freshwater Alga and Cyanobacteria, GrowthInhibition Test (Adopted: March 23, 2006) .

The Toxicity rest was performed with control and nominal concentrations of 6.3, 12.5, 25.0, 50.0 and 100.0 mg/L each in triplicates, with mean measured concentrations of 7.5, 14.5, 29.8, 56.7 and 109.6 mg/L, respectively. Cultures were incubated on a shaking incubator under continuous illumination at 24.0 +/- 0.2 oC for 72 hours. Growth was monitored daily by determining the cell density of each culture by direct counts using a BECKMAN COULTERTM Multisizer 3 particle analyzer.

The following values, expressed in terms of the mean measured concentrations, were obtained from the test.

(Unit: mg/L, mean measured test concentration)

Estimates of Toxicity	Calculation Method
	Average Growth Rate	Yield
72-hr EC10 (95% confidence limits)	37.7 (21.9-48.1)	5.8 (1.1-10.9)
72-hr EC20  (95% confidence limits)	49.2 (34.1-59.2)	10.9 (3.5-17.3)
72-hr EC50  (95% confidence limits)	77.9 (66.2-92.8)	32.0 (21.3-48.6)
No  Observed Effect Concentration(NOEC)	< 7.5	<7.5
Lowest Observed Effect Concentration(LOEC)	7.5	7.5

All results were expressed in terms of the mean measured concentration (geometric mean). At 0 -hour (the start of the test), the mean measured concentrations were 7.5, 14.6, 29.9, 57.4 and 110.6 mg/L (110.6 -119.6% of the nominal concentration). The mean concentrations measured at 72 -hour (the end of the test) were 7.6, 14.5, 29.8, 56.0 and 108.7 mg/L (108.7 -120.6 % of the nominal concentration).

Description of key information

The read-across 72hr-EC50 values (95% confidence limits) expressed in terms of the mean measured concentration of phosphoric acid (CAS No. 7664-38-2) to Pseudokirchneriella subcapitata (Strain No . UTEX 1648) were determined as 77.9 mg/L (66.2-92.8 rng/L) for average growth rate, and 32.0 mg/L (21.3-48.6 mg/L) for yield, respectively.