Iron orthophosphate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study, data originate in part from a secondary source

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control and 100 mg/L. Samples were taken at 0 and 48 h

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution of test substance was prepared by adding 1.0111g to the test water and fill up to the marker in 100 mL volumetric flask. 2 mL of stock solution was added in the test water and filled up to the marker in 200 mL beaker to prepare test solutions.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Age at study initiation (mean and range, SD): <24 h
- Source: Environmenal toxicity lab., Safety Assessment Center, Korea Testing and Research Institute
- Food type (breeding): unicellular green algae, Chlorella vulgaris, daily

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

224 mg/L CaCO3

Test temperature:

20.28 ± 0.2 °C

pH:

7.8-8.14

Dissolved oxygen:

7.73-8.18 mg/L

Nominal and measured concentrations:

Nominal test concentration: 100 mg/L
The mean concentration was analyzed to be 2.75 mg/L at a nominal concentration of 100 mg/L (2.9% of nominal concentration) at 0 and 48 hours.

Details on test conditions:

TEST SYSTEM
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M4 medium


OTHER TEST CONDITIONS
- Photoperiod: 16:8 h day-night regime

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Immobility after 0, 24 and 48 hours

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: control, 0.1, 1, 10, and 100 mg/L.
- Results used to determine the conditions for the definitive study: No immobility was observed at 100 mg/L

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 2.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

After 24 hours and 48 hours exposure, no daphnia was immobilised in 100 mg/L of test solution. No abnormal behavior and intoxication symptoms were observed in control and treatment groups during limit test.

Reported statistics and error estimates:

No statistics performed

Table 1. Cumulative immobilization data forDaphnia magna

Nominal concentration (mg/L)	Measured concentration (mg/L)	Number of daphnids tested	Cumulative immobilized Daphnia magna (%)
			24 hours	48 hours
Control	ND	30	No immobilization	No immobilization
100	2.9	30	No immobilization	No immobilization

Table 2. Symptoms on intoxication of the test substance toDaphnia magna

Nominal concentration (mg/L)	Measured concentration (mg/L)	Symptoms of intoxication
		24 hours	48 hours
Control	ND	NOR (30)	NOR (30)
100	2.9	NOR (30)	NOR (30)

ND : Not detected, ( ) : Number of Daphnia magna, NOR : Normal

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

GLP compliance:

no

Remarks:

Conduction of studies under GLP conditions is not a requirement for peer reviewed publications.

Specific details on test material used for the study:

99.9% pure Iron(III) chloride hexahydrate (Wako)

Analytical monitoring:

yes

Remarks:

ICP-MS

Details on sampling:

- Sampling and concentrations: all tested concentrations were sampled at the start and at the end of the experiment

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Iron(III) chloride hexahydrate: Stock solution was prepared by dissolution of Iron(III) chloride hexahydrate in distilled water. Solution was then added to breeding water for the experiments.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Source: laboratory culture
- Age of parental stock: Female Daphnids (<24 h old), produced by mature females (≥ 2 weeks old), were subcultured every week.

ACCLIMATION
- Acclimation period: Daphnia magna was used for experiments after the acclimation of several generations.

BREEDING:
- Water temperature: 21 ± 1°C
- Light/dark cycle: 16/8 h
- Breeding vessel: In glass flasks using 35 adult daphnids per liter.
- Medium: Tap water in Tsukuba filtered with activated charcoal and renewed every second day.
- Food source: Chlorella vulgaris (diluted to 5 × 10^8 cell/ml)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

21 ± 1°C

pH:

6.5–8.5

Nominal and measured concentrations:

Five test concentrations were used up to 100 mg/L.

Details on test conditions:

TEST SYSTEM
- No. of vessels per control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: breeding water was used as test medium.
- Intervals of water quality measurement: The pH, dissolved oxygen and temperature were measured at the start and end of tests. The hardness of breeding water was measured in a series of tests.

OTHER TEST CONDITIONS
- Adjustment of pH: yes with 1 M sodium hydroxide
- Photoperiod: 16 h light/8 h dark

Reference substance (positive control):

not specified

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

6.7 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Reported statistics and error estimates:

EC50s were estimated by probit analysis.

Pure Fe (III) was considered to have a low toxicity to D. magna with an EC50 (48 h) of 2.3 mg/L.

Validity criteria fulfilled:

not specified

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Remarks:

Summary of available data used for the endpoint assessment of the target substance

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to the analogue justification attached to chapter 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 2.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: RA from CAS 7757-93-9

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: iron metal

Basis for effect:

mobility

Remarks on result:

other: RA from Iron (III) Chloride

Description of key information

No acute toxicity effects towards aquatic invertebrates up to the limit of water solubility.

Additional information

Iron (III) orthophosphate (CAS 10045-86-0) is a poorly water-soluble substance, as shown by a transformation/dissolution test according to the OECD guideline 29. The short term toxicity of Iron (III) orthophosphate towards aquatic invertebrates was evaluated in a weight of evidence approach with read across data. The short term effects by dissolved Fe³⁺were assessed using a soluble iron (III) form (FeCl₃) while the acute toxicity of PO₄^3-was assessed based on the reference substance Calcium hydrogenorthophosphate (CAS 7757-93-9). An extensive read across justification is provided in IUCLID chapter 13.

The potential toxicity of dissolved iron (III) to aquatic invertebrates was studied by Okamotoa et al. (2014) following the OECD guideline 202. A soluble iron (III) source (i.e. FeCl₃) was used for the study in order to study the effects of free Fe³⁺ions. Daphnia magna was used as the test organism and was exposed in a static regime to 5 test item concentrations up to 100 mg/L (nominal) for 48 h. An analytical monitoring was performed by ICP-MS. Pure Fe (III) was considered to have a low toxicity to D. magna with an EC50 (48 h) of 2.3 mg Fe³⁺/L, corresponding to an ERV_compound (ecotoxicity reference value) for Iron (III) orthophosphate of 6.34 mg/L. The transformation/dissolution test according to OECD 29 showed that the release of iron from the substance after 7 days was lower than the LOD of 0.1682 µg/L at a loading of 1 mg/L (pH 6). This concentration is far below the conservative effect concentrations found in the study with FeCl₃as reference substance. Therefore, no effects from the dissociated iron species released by the substance are expected up to the water solubility of Iron (III) orthophosphate. It has to be emphasized that the effect values with the soluble iron (III) form represent a worst case since iron (III) is under standard environmental conditions not mobile and will rapidly precipitate to poorly water soluble substances.

The acute toxicity of Calcium hydrogenorthophosphate (CAS 7757-93-9) to aquatic invertebrates was investigated in a study following OECD guideline 202 (2013). The study was conducted as a limit test under static conditions. Daphnia magna were exposed to a nominal test substance concentration of 100 mg/L for 48 h. The mean measured substance concentration was 2.75 mg/L. Mortality or symptoms of intoxication were not observed. At test termination an EC50(48 h) of >2.75 mg/L (nominal: EC50(48 h) >100 mg/L) based on the mean measured concentration was determined. Based on the study results Calcium hydrogenorthophosphate (CAS 7757-93-9) is not considered acutely toxic to aquatic invertebrates. Since Calcium hydrogenorthophosphate will dissociate to its ions calcium and phosphate and its solubility is much higher than iron (III) orthophosphate, it is concluded that similarly no effects are expected by the phosphate ions resulting from Iron (III) orthophosphate. 

In addition, the publically available Renewal Assessment Report (2013) for use of ferric phosphate in plant protection products also concludes based on experimental data with the active substance that the substance is not acutely toxic to aquatic invertebrates up to a loading rate of 100 mg/L. The study was conducted according to the OECD guidelines 202 and GLP. These data support the above conclusions from the read across data.

In conclusion based on the above described results, no short term effects by Iron (III) orthophosphate towards aquatic invertebrates are expected.