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TOXICITY TO FISH

Short-term toxicity to fish

The acute toxicity of the test itemPhosphorpentoxid(batch no.:DEH2018965)to fish (zebrafish) was determined according to OECD-Guideline for Testing of Chemicals No. 203 (1992) from2009-12-14 to 2009-12-18atDr.U.Noack-Laboratorien, 31157 Sarstedt , Germany. A static test with 5 test concentrations 10 – 18 – 32 – 56 - 100 mg/L (factor 1.78) and for pH-control an additional replicate of the highest concentration with correction of the pH-value was performed. Duration of the test was 96 h. 7 test organisms were exposed to each test concentration and control. Water quality parameters pH-value, temperature and oxygen-saturation measured after 0, 24, 48, 72 and 96 h were determined to be within the acceptable limits. The concentrations of the test itemPhosphorpentoxidwere analysed via standardized photometric test at all concentration levels at test start and test end. Recovery rates ofPhosphorpentoxidat the beginning of the study were in the range of 80 - 98 % and at the end in the range of 49 – 100 % of the nominal values. For details of the analytical results please refer to part 9. At the test item concentration of 56 and 100 mg/LPhosphorpentoxidcaused pH-related lethal effects whereas a concentration of 100 mg/L with adjustment of the pH-value to 6.97 did not cause any effects. All effect levels are given based on nominal concentrations of the test itemPhosphorpentoxid.

LC-Values with 95 % Confidence Intervals

                                              (based on nominal test item concentrations)

ValueswithAdjustment of pH

ValueswithoutAdjustment of pH

Test duration [h]

LC50

p = 95 % [mg/L]

LC50

p = 95 % [mg/L]

24

> 100

n. a.

42

32 - 56 *

48

> 100

n. a.

42

32 - 56 *

72

> 100

n. a.

42

32 - 56 *

96

> 100

n. a.

42

32 - 56 *

LC100=

> 100

56

Lowest test item concentration

with 100 % mortality after 96 h

LC0=

   100

32

Highest test item concentration

with 0 % mortality after 96 h

NOEC (0-96 h) =

No observed effect concentration

   100

32

Long-term toxicity to fish

Diphosphorus pentaoxide is hygroscopic forming with water an aqueous solution of phosphorus oxyacids (primary hydrolysis) which are subject to further (secondary) hydrolysis to the end product phosphoric acid, H3PO4.

Hydrolysis of P2O5 in water under conditions relevant for ecotoxicological studies (100mg/L, 25°C) leads to slightly acidic solutions(pH 3.6) with the main product of tetraphosphoric acid. Further hydrolysis within the time frame of ecotoxicological studies is insignificant.

Under environmental conditions the hydrolysis products are available as different phosphate (Na, K, Ca). Phosphate and phosphorus are an essential nutrient of microorganisms, plants and animals. Phosphoric acid is readily utilizable by aquatic plants and microorganisms. Phosphorus compounds are an important component of living matter and all organisms contain a certain quantity.

Short-term toxicity tests are available according Annex VII, Column 1, 9.1.1 and 9.1.2 and according Annex VIII, Column 1, 9.1.3 and 9.1.4. The chemical safety assessment according Annex I does not indicate the need to investigate further the effects on aquatic organisms. Based on the results of the short-term toxicity tests long-term toxicity tests are not warranted.

TOXICITY TO DAPHNIA

Short-term toxicity to aquatic invertebrates

The acute immobilization of the test item Phosphorpentoxid (batch number: DEH2 018965) toDaphnia magna(STRAUS) was determined according toOECD 202 (2004)from 2010-02-03 to 2010-02-05 atDr.U.Noack-Laboratorien, Käthe-Paulus-Str. 1, D-31157 Sarstedt, Germany.
The study was conducted with 5 nominal test item concentrations ranging from 6.25 to 100 mg/L set up in a geometric series with a dilution factor of 2 under static conditions over a period of 48 h. Additionally a pH control was tested. 20 test organisms were exposed to each test concentration and control.

The phosphate content as a component of the test itemPhosphorpentoxidwas analysed viaUV-spectrophotometrywith a pipette test at all test item concentrations, the pH control and the control after 0 h and 48 h. Details of the analytical method are given in part10.The recovery rates in the fresh (0 h) and old media (48 h) of the tested concentration levels were in the range of 86 % to 98 %of the nominal values.All effect values are given based on the nominal concentrations of the test item Phosphorpentoxid.Phosphorpentoxid only caused a pH-related toxic effect at the concentration level 100 mg/L whereas a concentration of 100 mg/L with adjustment of the pH-value from 3.32 to 7.03 did not cause any effects.
Water quality parameters (pH-value and dissolved oxygen concentration), measured at 0 h and 48 h, were determined to be within the acceptable limits. The validity criteria of the test guideline were fulfilled.

Table1:   EC10-, EC50- (with Confidence Interval), EC100- Values, NOEC and LOEC

(based on the nominal concentrations of the test itemPhosphorpentoxid)

ValueswithAdjustment of pH

ValueswithoutAdjustment of pH

Test

Duration
[h]

Nominal Concentration of the Test Item
Phosphorpentoxid
[mg/L]

EC10

24

> 100

Not applicable

48

> 100

Not applicable

EC50

with 95 % confidence

limits (Cl)

24

> 100 (Cl: Not applicable)

 70.7 (Cl: 50.0 – 100)

48

> 100 (Cl: Not applicable)

 70.7 (Cl: 50.0 – 100)

EC100

24

> 100

100

48

> 100

100

NOEC

48

   100

 50.0

LOEC

48

> 100

100

Long-term toxicity to aquatic invertebrates

Diphosphorus pentaoxide is hygroscopic forming with water an aqueous solution of phosphorus oxyacids (primary hydrolysis) which are subject to further (secondary) hydrolysis to the end product phosphoric acid, H3PO4.

Hydrolysis of P2O5 in water under conditions relevant for ecotoxicological studies (100mg/L, 25°C) leads to slightly acidic solutions(pH 3.6) with the main product of tetraphosphoric acid. Further hydrolysis within the time frame of ecotoxicological studies is insignificant.

Under environmental conditions the hydrolysis products are available as different phosphate (Na, K, Ca). Phosphate and phosphorus are an essential nutrient of microorganisms, plants and animals. Phosphoric acid is readily utilizable by aquatic plants and microorganisms. Phosphorus compounds are an important component of living matter and all organisms contain a certain quantity.

Short-term toxicity tests are available according Annex VII, Column 1, 9.1.1 and 9.1.2 and according Annex VIII, Column 1, 9.1.3 and 9.1.4. The chemical safety assessment according Annex I does not indicate the need to investigate further the effects on aquatic organisms. Based on the results of the short-term toxicity tests long-term toxicity tests are not warranted.

TOXICITY TO ALGAE

The toxicity ofPhosphorpentoxid(batch number DEH2018965)to the unicellular freshwater green algaDesmodesmus subspicatuswas determined according to the principles of OECD 201atDr.U.Noack-Laboratorienin 31157 Sarstedt, Germanyfrom February 9thto July 2ndwith the definitive exposure phase from June 29thto July 2nd, 2010.The aim of the study was to assess the effects on growth rate and yield over a period of 72 h.

The study was conducted under static conditions with an initial cell density of approximately  2 – 5 x 103cells/mL. Five concentration levels were tested in a geometrical series with a dilution factor of 2, nominal: 12.5 - 25.0 - 50.0 - 100 - 200 mg/L.In order to exclude possible effects due to the pH-value all test concentrations were tested by correction of the pH-value.Three replicates were tested for each test item concentration and six replicates for the control.Environmental conditionswere determined to be within the acceptable limits.

The concentrations ofPhosphorpentoxidwereanalysed at all concentration levels after 0 and 72 h via standardized photometric test. The measured concentrations ofPhosphorpentoxidat test start were in the range of 89 – 93 % of the nominal values.At the end of the testPhosphorpentoxidgave recoveries of 79 – 97 % of the nominal values.All effect values are given based on nominal concentrations of the test item.

NOEC, LOEC, EC - values and 95 % Confidence Intervals of Phosphorpentoxid(0-72 h)

                  based on nominal test item concentrations [mg/L]

                               

Rate-related Inhibition

NOEC

25.0

LOEC

50.0

ErC10

39.4 (37.2 – 41.5)

ErC20

48.6 (47.3 – 50.0)

ErC50

66.5 (64.0 – 69.7)

Inhibition of Yield

NOEC

12.5

LOEC

12.5

EyC10

12.5

EyC20

16.3 ( 12.5 – 22.8)

EyC50

38.0 (34.2 – 41.2)

The toxicity ofPhosphorpentoxid(batch number DEH2018965)to the unicellular freshwater green algaDesmodesmus subspicatuswas determined according to the principles of OECD 201atDr.U.Noack-Laboratorienin 31157 Sarstedt, Germanyfrom February 9thto July 2ndwith the definitive exposure phase from June 29thto July 2nd, 2010.The aim of the study was to assess the effects on growth rate and yield over a period of 72 h.

The study was conducted under static conditions with an initial cell density of approximately  2 – 5 x 103cells/mL. Five concentration levels were tested in a geometrical series with a dilution factor of 2, nominal: 12.5 - 25.0 - 50.0 - 100 - 200 mg/L.In order to exclude possible effects due to the pH-value all test concentrations were tested by correction of the pH-value.Three replicates were tested for each test item concentration and six replicates for the control.Environmental conditionswere determined to be within the acceptable limits.

The concentrations ofPhosphorpentoxidwereanalysed at all concentration levels after 0 and 72 h via standardized photometric test. The measured concentrations ofPhosphorpentoxidat test start were in the range of 89 – 93 % of the nominal values.At the end of the testPhosphorpentoxidgave recoveries of 79 – 97 % of the nominal values.All effect values are given based on nominal concentrations of the test item.

NOEC, LOEC, EC - values and 95 % Confidence Intervals of Phosphorpentoxid(0-72 h)

                  based on nominal test item concentrations [mg/L]

                               

Rate-related Inhibition

NOEC

25.0

LOEC

50.0

ErC10

39.4 (37.2 – 41.5)

ErC20

48.6 (47.3 – 50.0)

ErC50

66.5 (64.0 – 69.7)

Inhibition of Yield

NOEC

12.5

LOEC

12.5

EyC10

12.5

EyC20

16.3 ( 12.5 – 22.8)

EyC50

38.0 (34.2 – 41.2)

TOXICITY TO MICROORGANISMS

A Respiration Inhibition Test according to OECD Guideline No. 209 was performed with the test item Phosphorpentoxid (batch-no. DEH2 018965) on 2010-01-07 atDr.U.Noack-Laboratorien, D-31157Sarstedt.Test system was activated sludge of the municipal treatment plant of D-31157 Sarstedt. The test was performed under static conditions with the nominal concentrations   100 - 180 - 320 - 580 - 1000 mg/L without adjustment of pH and 320 - 580 - 1000 mg/L adjusted to pH 7 to differentiate between pH effects and test item effects. The respiration rates of control, reference and test item concentrations were measured after a contact time of three hours, and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. The inhibition of the test item ranged from 15 % to 100 %. The neutralised test item concentrations showed inhibitions from 10 % to 44 %. The EC20-, EC50- and EC80-values were calculated by sigmoidal dose-response regression for the test item concentrations without adjustment of pH and by probit analysis for the test item concentrations adjusted to pH 7.

Table 1:           EC-Values with Confidence Interval of Phosphorpentoxid

Valueswithoutadjustment of pH

Valueswithadjustment of pH

EC-values

Confidence interval

EC-values

Confidence interval

[mg/L]

P = 95 [%]

[mg/L]

[mg/L]

P = 95 [%]

[mg/L]

EC20

147

-

524

-

EC50

215

209 - 220

>1000

>1000

EC80

275

-

>1000

-

In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC50-value for the reference item was 101 mg/L.