Trixylyl phosphate

Endpoint summary

Description of key information

The substance is considered to be toxic to aquatic invertebrates on the basis of available information.

Additional information

Fish

 

Acute

 

Fathead minnows, Pimphales promelas, were exposed to five concentrations of Phosflex TXP under flow-through conditions for 96 hours. The 96 hour LC50 value was >1119 µg/L, the highest concentration measured. The 96-hour no mortality concentration and 96 hour NOEC were both 1119 µg/L.

No toxicity at the limit of solubility in water was therefore noted.

 

Chronic

 

No toxicological effects with fish are noted at the limit of solubility in water in acute studies, and as such, it is proposed that longer term effects are unlikely to be prominent. The substance is classified for environmental effects; however this is based on toxicity to aquatic invertebrates rather than to fish. On animal welfare grounds and the fact that the testing will not contribute to the overall classification, this test is waived.

 

Daphnia

 

Acute

 

The cladoceran, Daphnia magna, was exposed to eight concentrations of Phosflex TXP under static-renewal conditions for 48 hours. Based on the mean, measured test concentrations, the 48 hour EC50 value was 60 µg/L, with a 95% confidence interval of 49 to 107 µg/L. The no observed effect concentration (NOEC) was 11 µg/L.

Classification as "very toxic to aquatic organisms" is applicable.

 

Chronic

 

As a weight of evidence approach, it is considered appropriate to utilise a geometric mean for the data on Daphnia in order to derive an appropriate NOEC for use in hazard assessment. The document “Guidance on information requirements and chemical safety assessment Chapter R.10: Characterisation of dose [concentration]-response for environment”states under section“R.10.2.2 Evaluation and interpretation of data”that:

 

Where there is more than one set of data on the same species, (strain if known), endpoint, duration, life stage and testing condition the greatest weight is attached to the most reliable and relevant one. When there is more than one set of data with the same reliability rating, it might be necessary to look into more detail at the study reports to see whether a specific reason could explain the difference. If no explanation can be found and the results are for the same species and endpoints and are not more than one order of magnitude apart, they can be harmonised by a geometric mean.

 

A geometric mean 21-day NOEC is therefore applied for the purposes of hazard assessment.

 

Daphnia
Substance	Endpoint	Result	M or N	Trade name	Basis for effect
Phenol, isopropylated, phosphate(3:1)	21 d NOEC	0.027 mg/L	nominal	Trade Name Kronitex 200	Survival
	21 d NOEC	0.006 mg/L	nominal	Trade Name Kronitex 200	reproduction
	21 d NOEC	0.028 mg/L	nominal	Trade Name Phosflex 31P	Survival
	21 d NOEC	0.028 mg/L	nominal	Trade Name Phosflex 31P	reproduction
Tricresyl phosphate, CAS 1330-78-5 EC 215-548-8	21 d NOEC	0.1 mg/L	nominal	N/A	mortality
	21 d NOEC	0.1 mg/L	nominal	N/A	reproduction
Geometric mean 21 Day NOEC: 0.03290828 mg/l
Gammarus pseudolimnaeus
Phenol, isopropylated, phosphate(3:1)	90 d NOEC	0.011 mg/L	nominal	Trade Name Kronitex 200	Survival
	90 d NOEC	0.063 mg/L	nominal	Trade Name Kronitex 200	Growth
	90 d NOEC	0.019 mg/L	nominal	Trade Name Phosflex 31P	Survival
	90 d NOEC	>= 0.088 mg/L	nominal	Trade Name Phosflex 31P	Growth
Chironomus plumosus
Phenol, isopropylated, phosphate(3:1)	30 d NOEC	0.184 mg/L	nominal	Trade Name Kronitex 200	Emergence
	30 d NOEC	0.184 mg/L	nominal	Trade Name Phosflex 31P	Emergence

 

Algae

 

Selenastrum capricornutum were exposed to five concentrations of Phosflex TXP and evaluated for effects on cell density, area under the growth curve and growth rate. The 72 and 96-hour EC50, based on cell density, area under the growth curve and growth rate, was > 1011 µg/L, the highest tested concentration. The 72 hour NOAEC, based on cell density and area under the growth curve (biomass) was 112 µg/L. The 96-hour NOAEC based on cell density was 112 µg/L.

No toxicity at the limit of solubility in water was therefore noted.

 

Toxicity to microorganisms

 

In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited between 4.2 % and 12.5 % in the examined nominal test concentration range (10 - 1000 mg/L). Concentrations exceeding 1000 mg/L nominal were not tested.

 

In parallel to the study with the test item, the reference item 3,5-Dichlorophenol was tested (the nominal test concentrations of 5, 16 and 32 mg/L) under otherwise identical test conditions.

 

The 3-hour EC₅₀of 3,5-Dichlorophenol was calculated to be 9.46 mg/L with 95 % confidence limits of 7.40 to 12.11 mg/L.

 

Based on measured inhibition rates it can be stated that the 3-hour EC₂₀, EC₅₀and EC₈₀were higher than 1000 mg/L.

 

The NOEC was determined to be 1000 mg/L.

 

The NOEC for respiration rates was not based on the results of a statistical analysis, but it is biologically justified. The respiration rates were inhibited and influenced dose dependently in the whole concentration range, and the observed slight inhibition (12.5 %) at the concentration level of 1000 mg/L was evaluated as reflecting the biological variability in the test. The calculated respiration rate, 0.420 (at 1000 mg/L) was not in the historical control data range (0.524±0.070), but the deviation from the control was within +/- 15 %, it can be considered as a biological variability of the test system.