Phosphoric acid, isononyl ester

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.049 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.49 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.005 mg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

15 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Sediment (marine water)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no exposure of soil expected

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

16.7 mg/kg food

Assessment factor:

300

Additional information

No reliable toxicity data is avaiable for isononyl phospate. However, reliable toxicity data is available for the analogue, phosphoric acid, 2-ethylhexyl ester, and included in the dossier. The substance is not classified for the environment, but an algal inhibition study did show that the algae was affected by the presence of the test item over a 72 -hour exposure period. Therefore, PNECs have been derived where appropriate.

PNEC water:

PNECs have been derived based on the results of freshwater and marine algal inhibition studies. However, the PNECs derived should be treated with caution as the results come from studies conducted using Water Accommodated Fractions (WAFs).

WAFs may be used in cases where the test item is a complex mixture and is poorly soluble in water and in permitted auxiliary solvents and surfactants. Exposures to the test organisms are expressed in terms of the original concentration of test item in water at the start of the mixing period (loading rate) irrespective of the actual concentration of test item in the WAF.

Therefore, as the substance comprises two constituents of varying solubility (one constituent being of low solubility), it was considered appropriate to conduct the aquatic toxicity testing using WAFS

Given that toxicity cannot be attributed to a single component or a mixture of components but to the test item as a whole, results of the aquatic toxicity tested conducted, including the algal inhibition study, were based on nominal loading rates only.

It can be considered that from acute studies with the analogue, phosphoric acid, 2-ethylhexyl ester, conducting with WAFs, toxicity data is more likely to correspond to the toxicity of the more soluble component(s) i.e. 2-ethylhexyl dihydrogen phosphate. This component is not classified for the environment according to the C&L inventory on the ECHA website.

PNECs derived from studies conducted using WAFs should be viewed with caution according to the ECHA Guidance; Guidance on information requirements and chemical safety assessment Chapter R.7b: Endpoint specific guidance.

The nominal loading rates cannot be used to derive a PNEC, since partitioning in the environment will make the comparison with a PEC meaningless.

Therefore, the PNECs derived for water need to be treated which caution, as they may not reflect the substances individual constituents behaviour.

PNEC oral:

A PNEC oral has been derived. However, due to limited release of the substance to the environment and the lack of bioaccumulation potential of the substance, secondary poisoning is not anticipated to be of concern.

 

Conclusion on classification

The substance is not classified for the environment based on the results of acute toxicity testing studies conducted on fish, invertebrates, and algae, with representative species from both freshwater environments. The results of a ready biodegradation test and the substance physico-chemical properties, such as water solubility and partition coefficient, have also been taken into account.

 

The acute toxicity testing was conducted using Water Accomodated Fractions (WAF) of the test substance (see discussion sections of studies). Given that toxicity (if observed) cannot be attributed to a single component (or a mixture of components) but to the test item as a whole the results were based on nominal loading rates only, and are summarised below:

Acute toxicity to fish: The 96-Hour LL₅₀ (lethal loading rate) based on nominal loading rates was greater than 100 mg/l loading rate WAF and correspondingly the No Observed Effect Loading rate was 100 mg/l loading rate WAF.

Acute toxicity to Daphnia magna: The 48-Hour EL₅₀ (effective loading rate) for the test item to Daphnia magna based on nominal loading rates was greater than 100 mg/l loading rate WAF. The No Observed Effect Loading rate was 100 mg/l loading rate WAF.

Acute toxicity to Acartia tonsa: The 48-Hour LL₅₀(lethal loading rate) based on nominal loading rates was 117.4 mg/L.

Acute toxicity to freshwater algae:

EL₅₀(growth rate):49mg/l

No Observed Effect Loading Rate: 25 mg/l

The acute lethal loading level (expressed as the LL/EL₅₀) is comparable to the LC/EC₅₀ values determined for pure substances tested within their solubility range. They can therefore be used directly for classification.

 

Based on the results of the acute studies no lethal or sub-lethal effects were observed in fish or invertebrates magna at loading rates of 100 mg/l WAF.

 

For algae, the growth rate EL₅₀ of 49 mg/l for freshwater species, is not sufficient for classification of the substance in Chronic Category 3 (for substances with a 72 hr ErC50 for algae of >10 to ≤100 mg/l), as the substance does not meet the other criteria required for Chronic Category 3 classification, which state the substance must also not be rapidly biodegradable and/or have an experimentally determined BCF≥500 (or log Pow≥ 4).

Therefore, the substance does not meet the criteria for classification for the environment.