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Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
0.02 mg/L
Assessment factor:
1
Extrapolation method:
sensitivity distribution
PNEC freshwater (intermittent releases):
0.02 mg/L

Marine water

Hazard assessment conclusion:
PNEC aqua (marine water)
PNEC value:
0.02 mg/L
Assessment factor:
1
Extrapolation method:
sensitivity distribution
PNEC marine water (intermittent releases):
0.02 mg/L

STP

Hazard assessment conclusion:
PNEC STP
PNEC value:
0.24 mg/L
Assessment factor:
1
Extrapolation method:
sensitivity distribution

Sediment (freshwater)

Hazard assessment conclusion:
PNEC sediment (freshwater)
PNEC value:
13.99 mg/kg sediment dw
Assessment factor:
1
Extrapolation method:
equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:
PNEC sediment (marine water)
PNEC value:
13.99 mg/kg sediment dw
Assessment factor:
1
Extrapolation method:
equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:
no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:
PNEC soil
PNEC value:
2.81 mg/kg soil dw
Assessment factor:
1
Extrapolation method:
equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
no potential for bioaccumulation

Additional information

Reaction Products of C3 alcohols and C3 alkenes obtained as by-products from the manufacture of propan-2-ol by hydration of propylene is a UVCB stream, therefore PNECs cannot be derived by conventional means, that is by applying an assessment factor to whole stream ecotoxicity data.

Instead, the PNEC has been based on the constituent of the stream considered to present the greatest risks to the aquatic environment, taking into account ecotoxicity and typical concentration. For this stream, C9 alkanes were found to represent a worst case, therefore the PNEC for the stream will be based on this class of substance.

To calculate a PNEC for C9 alkanes, the HC5 QSAR equation (Di Toro et al, 2000a, 2000b, McGrath and Di Toro 2004, McGrath and Di Toro 2009, Redmann et al 2009) was selected. This model calculates an HC5 based on average physical chemical properties of the C9 iso, n paraffin hydrocarbon block and has been derived using a range of organisms (47 species) in the training set including plants, invertebrates and fish, both fresh and marine.

Conclusion on classification

Short-term aquatic toxicity tests with fish, invertebrates and algae have been conducted using a Water‑Accommodated Fraction (WAF) methodology, as described below. This approach is consistent with the recommendations of the OECD Guidance Document on aqueous-phase aquatic toxicity testing of difficult test chemicals (OECD GD 23; 2nd Edition; 2019) for ecotoxicity testing of UVBCs that are only partially soluble in water. Since only a fraction of the total mass of the UVCB is expected to be present in the WAF, the term “loading rate” is used to express the exposures instead of “nominal concentrations”.

Based on the loading rates, the 96-hour LL50 for fish is 18 mg/L, for aquatic invertebrates the 48-hour EL50 is 35 mg/L and the lowest 72-hour EL50 for algae is 160 mg/L for both biomass and growth. The EC50 for microorganisms is >320 mg/L.

As requested by ECHA, the recalculated effect levels based on mean measured concentrations in test media samples from the fish, Daphnia and algae studies gave L(E)C50values of 6.8, 14 and >34 mg/L, respectively.

In accordance with column 2 of REACH Annex IX, the long-term testing on aquatic species does not need to be conducted as the chemical safety assessment according to Annex I has not indicated a need to investigate further the long-term effects on aquatic organisms. Chronic toxicity classification of IPE was determined based on the acute toxicity data and environmental fate data i.e. the lack of ready biodegradability and an estimated log Kow ≥4. 

The REACH technical guidance on the application of the CLP criteria (Version 5.0 July 2017) states that the effect concentration values based on the loading levels from a Water Soluble Fraction (WSF) or Water Accommodated Fraction (WAF) may be used directly in the classification criteria, in agreement with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS; 8th edition; 2019). This is also consistent with the OECD Guidance Document on the Use of the Harmonised System for the Classification of Chemicals which are Hazardous to for the Aquatic Environment (OECD GD 27; 2001) and the OECD Guidance Document on aqueous-phase aquatic toxicity testing of difficult test chemicals (OECD GD 23; 2019). These different guidance documents state that the data derived from the testing of WAFs are reported in terms of loading rates which may be used in applying the classification criteria. In addition, the ECHA Endpoint specific guidance (Chapter R.7b; Version 4.0; June 2017) also states that “the acute lethal loading level (typically expressed as the E(L)L50) is comparable to L(E)C50 values determined for pure substances tested within their solubility range”. Again, underscoring the intention that E(L)L50 values may be used directly for classification.

These recommendations are made for complex substances, such as IPE, since the various fractions will have different equilibria in water which may be a characteristic of the loading. For this reason, such complex substances are usually tested as a WSF or WAF, and the L(E)C50 reported based on the loading rate levels. The measured concentrations of dissolved and/or emulsified key or major components can be performed to improve interpretation of the data (OECD GD 23; 2019). This was reflected in the ECHA response letter of January 2019. However, since such analyses do not reflect the ‘whole’ substance it would not be appropriate to use such measured values of selected fractions for classification purposes of IPE.

IPE meets the criteria for complex substances discussed above. Consequently, best practice was followed regarding the preparation of the WAFs and study conduct. Before application in the fish, Daphnia and algae studies, the mixing period was validated. The demonstrated maximum dissolved levels (assessed by Total Organic Carbon as a measure of soluble organic substances) were achieved after 24 hours of mixing. Subsequently, individual WAFs were prepared in a standardised manner for each treatment level since component solubility may depend on loading rates (mass to volume ratios). After addition of the test item to the test medium, solutions were stirred until a small dimple was formed at the surface. Vessels were filled to exclude headspace and sealed in order to minimise volatile losses. WAFs were stirred for 23 hours and then let to settle for 1 hour, after which the aqueous portion was sampled and microscopically confirmed to be free of micro-dispersions and undissolved materials. Therefore, every precaution was taken to ensure that equilibrium of the test material to aqueous phase was achieved in a consistent and reproducible manner across treatments. It is important to highlight that the dissolved test material to which the fish, Daphnia and algae were exposed was not the entire test item but only the portion that was demonstrated to be dissolved and therefore bioavailable to the test organisms. Headspace gas chromatography was used to confirm dosing of the test system and to demonstrate that a concentration gradient was achieved. Consequently, the analytically determined test levels are not appropriate to express the test substance as a whole since by design the test system was only dosed with the dissolved fraction of the original test substance.

Therefore, for consistency with the above mentioned guidance documents, it is considered appropriate to base the Classification and Labelling of the test substance regarding hazards to the aquatic environmental on the loading rate levels of the WAFs rather than only on the dissolved fraction of the test material.

The environmental hazard classification for IPE, based on the criteria of Regulation (EC) No 1272/2008, is therefore Aquatic Chronic Category 3 since the short-term acute aquatic toxicity data falls within the range of >10 but ≤100 mg/L based on the loading rates, for a non-rapidly degradable substance (substance is not readily degradable) with log Kow ≥4.

References

OECD GD 23 http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2001)8&doclanguage=en

OECD GD 27 http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2001)8&doclanguage=en