Phosphoric acid, mono- and di-C6-10-alkyl esters

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.1 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

1 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.01 mg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

32 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

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:

insufficient hazard data available (further information necessary)

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

33.3 mg/kg food

Assessment factor:

300

Additional information

The substance is not classified for the environment. However, an algal inhibition study showed that growth rate and yield of Pseudokirchneriella subcapitata were affected by the presence of the test item over the 72-Hour exposure period. Algae was identified as the most sensitive species. The Daphnia magna study also showed some effects at the top concentration tested (25% Daphnia immobile at nominal loading rate of 100 mg/l).

PNECs have therefore been derived where appropriate. The aquatic PNECs have been based on the algal inhibition results for growth rate rather than yield, as the endpoint most frequently used for derivation of PNEC (from algal inhibition studies) is growth. The preferred observational endpoint in this study is also growth rate inhibition because it is not dependent on the test design, whereas biomass/yield depends both on growth rate of the test species as well as test duration and other elements of test design.

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 components of varying estimated solubility (predominately vey 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 conducting with WAFs, toxicity data is more likely to correspond to the toxicity of the more soluble component(s), such as the monoesters in this case.

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, which states:

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 components behaviour.

Based on this and that the substance is not classified for the environment, the derived PNECs have not been used in a quantitative assessment for environmental risk characterisation.

Conclusion on classification

The substance is not classified for the environment based on the results of acute toxicity testing studies conducted on fish (rainbow trout) , Daphnia magna and algae (Pseudokirchnerella subcapitata). 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 Accommodated Fractions (WAF) of the test substance (see

discussion sections of studies). The dissolved test item may have been one or several components of the test item. Given that toxicity cannot be attributed to a single component or 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. 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 56 mg/l loading rate WAF.

Algal inhibition:

ErL₅₀ (growth rate): >100 mg/l Loading Rate WAF

EyL₅₀ (yield): 1.1 mg/l Loading Rate WAF

No Observed Effect Loading Rate: <1.0 mg/l

The acute lethal loading level (expressed as the LL/EL₅₀) is comparable to the LC₅₀ 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, algae was determined to be the most sensitive species.

The ErL₅₀ (growth rate) was determined to be >100 mg/l loading rate WAF. Classification is based on the ErL₅₀ for

growth rate rather than yield/biomass (in accordance with CLP regulations).

Based the ErL₅₀ (growth rate) of >100 mg/l (and the LL/EL₅₀ results in fish and Daphnia) no environmental classification (in either Acute Category 1 or Chronic Categories 1, 2 and 3) is required, as no results are below 100 mg/l.

The substance is readily biodegradable (115% degradation after 28 days) and therefore classification in Chronic Category 4 is not applicable, despite the estimated low water solubility of substance components and partition coefficient (log Pow >6.5 worst case).