Neodymium di(2-ethylhexyl) phosphate

Endpoint summary

Additional information

All the data available were quoted as reliability 1 according to Klimisch criteria and flagged as key studies.

Short-term toxicity to fish:

The acute toxicity of neodymium tris(di-2-ethylhexylphosphate) was evaluated in the rainbow trout, Oncorhynchus mykiss, using a 96-hour semi-static test according to current EC, OECD and EPA test guidelines.

The stock solution was prepared at a loading rate of 100 mg/L (LS = Limit of Solubility). The stock solutions were stirred during approximately 96 hours. After a decantation phase, the test solutions were prepared by further dilution of this aqueous phase.

10 fish were exposed to the nominal concentrations of:

- 0 (control), LS/32, LS/16, LS/8, LS/4, LS/2 and LS for 96 hours in the first definitive test.

- 0 (control), LS/4, LS/2 and LS for 96 hours in the complementary definitive test.

Mortality and sub-lethal effects at each concentration were recorded at 0, 2, 4, 24, 48, 72 and 96 hours. The actual concentrations were measured at 24, 48, 72 and 96h hours.

 

Measured concentrations in both definitive test solutions dropped below 80% of the corresponding initial values during the tests. The test item was therefore not stable under the experimental conditions.

 

The 96h-LC50 of neodymium tris(di-2-ethylhexylphosphate) is > 100 mg/L based on nominal loading rate and > 2.56 mg/L in the first definitive test and > 2.58 mg/L in the complementary definitive test based on measured concentration (calculated from geometric mean of measured concentrations). The NOEC is 1.31 mg/L in the first definitive test and 2.58 mg/L in the complementary definitive test (geometric mean of measured concentration).

Neodymium tris(di-2-ethylhexylphosphate) is not harmful for fish up to its solubility limit into water.

 

Short-term toxicity to aquatic invertebrates:

The acute toxicity of neodymium tris(di-2-ethylhexylphosphate) was evaluated in Daphnia magna using a 48-hour semi-static test according to current EC, OECD and EPA test guidelines.

The stock solution was prepared at a loading rate of 100 mg/L (LS). The stock solutions were stirred during approximately 96 hours. After an up-to-2-hour decantation phase, the test solutions were prepared by further dilution of this aqueous phase.

20 daphnids (in four replicates of five) were exposed to the nominal concentrations of 0 mg/L (control), LS/16, LS/8, LS/4, LS/2 and LS for 48 hours. Immobilization of daphnids at each concentration was recorded at 0, 24 and 48 hours. The actual concentrations were measured at 24 and 48 hours.

 

Measured concentrations in the definitive test solutions dropped below 80% of the corresponding initial values during the test. The test item was therefore not stable under the experimental conditions.

 

No immobility was observed in the control treatment and at LS/16, LS/8, LS/4 and LS/2. At LS, 10 % of the organisms were immobilized after 48 hours; resulting in the following EC50 and NOEC values:

48-h EC50 > 1.68 mg/L (> 100 mg/L nominal)

48-h NOEC = 0.59 mg/L (= 50 mg/L nominal)

(as geometric mean measured concentration)

 

Neodymium tris(di-2-ethylhexylphosphate) is not harmful for daphnids up to its solubility limit into water.

 

 

Toxicity to aquatic algae:

The acute toxicity of neodymium tris(di-2-ethylhexylphosphate) was evaluated in the algal species Pseudokirchneriella subcapitata using a 72-hour static test according to current EC, OECD and EPA test guidelines.

 

The stock solution was prepared at a loading rate of 100 mg/L. The stock solution was stirred during 96 hours. After a decantation phase, the test solutions were prepared by further dilution of this aqueous phase (stock solution). Algal suspensions were exposed to the nominal concentration of 0 mg/L, LS/32, LS/16, LS/8, LS/4, LS/2 or LS for 72 hours. Cell counts were performed at 24, 48 and 72 hours allowing to determine growth rate and yield inhibition compared to control. Samples were taken daily to measure the actual concentration of the test item in all solutions and to measure the concentration of the phosphate, except for the control, during the exposure period.

 

Measured concentrations in the definitive test solutions with and without algae dropped below 80% of the corresponding initial values during the test. The test item was not stable under the experimental conditions. This decrease was due for one part to test item degradation and for another part to bioaccumulation and/or adsorption at the surface of the cells, since measured concentrations were more important in test solutions without algae than in test solutions with algae.

 

The following EC50 and NOEC values were obtained:

- Growth rate: 72-h ErC50 > 4.65 mg/L (> 100 mg/L nominal) and NOEC = 1.5 mg/L (50 mg/L nominal).

- Yield: 72-h EyC50 = 3.13 mg/L (2.87-3.43) and NOEC = 1.5 mg/L (50 mg/L nominal)

The observed test item effects were partially due to the interaction between the phosphate and the test item; leading to phosphate deprivation for the algae.

 

Neodymium tris(di-2-ethylhexylphosphate) is not harmful for algae up to its solubility limit into water.

 

Toxicity to microorganisms:

The effect of the test item neodymium tris(di-2-ethylhexylphosphate) on the respiration of activated sewage sludge was evaluated using a 3-hour static test according to OECD guideline No. 209 and US EPA/OPPTS 850.6800 Guideline.

Five concentrations of test item were tested: 10, 31.6, 100, 316 and 1000 mg/L. In parallel, two controls and three different concentrations of the reference item 3,5-dichlorophenol (4, 12 and 36 mg/L) were tested. After a 3-hour incubation time, the inhibition of the respiration rate was investigated via measurement of oxygen consumption rate.

 

As the validity criteria were met (the difference between the respiration rates of the two controls was below 15% and the EC50 of 3,5-dichlorophenol was 6.82 mg/L i.e. between 5 and 30 mg/L), the test was considered valid.

 

No significant inhibition (> 15%) of the respiration rate was noted in the test item suspensions at 10, 31.6, 100, 316 and 1000 mg/L, relative to mean of the controls.

Under the experimental conditions, the 3-hour EC50 of the test item for activated sludge respiration inhibition was > 1000 mg/L.

The test item should be considered as non-toxic for the micro-organisms of a water treatment plant.