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Endpoint summary

Description of key information

Waiver Justification & additional Endpoints

Additional information

Incroslip SL

Terrestrial Compartment

Background

Soil toxicity data are used in the chemical safety assessment to establish a PNEC_soil as part of a quantitative assessment of risk to the soil compartment. ECHA’s first preference would be for PNEC_soilto be calculated from long-term toxicity studies on soil organisms covering plants, invertebrates and micro-organisms.

 

For Incroslip SL, no such data existed at the time of dossier submission to ECHA for Annex X REACh registration (>1000t).

 

The initial proposal from Croda was to undertake an earthworm reproduction study, assess the results and submit a second proposal for testing or justification to ECHA. ECHA agreed to this proposal. Between the time of submission and the response from ECHA, an Earthworm Acute (OECD 207) study was conducted as a limit-test at 1000 mg/kg with no effects (NOAEC = 1000 mg/kg dry soil), LC₅₀>1000 mg/kg).

 

In light of this new ecotoxicology data for the soil compartment, the following information is available.

 

1a: Weight of Evidence

In general, where there is no toxicity L(E)C₅₀in the standard acute toxicity tests at >10 mg/l, or no effects in chronic toxicity at the limit of water solubility, or the screening assessment based on EPM shows no concern, then a single short-term soil test on a suitable species would be adequate to meet the requirements of Annex IX. For Incroslip SL the following experimental endpoints are available:

 

Short-term toxicity to fish                                              NOEC              100 mg/L (100% saturated solution)

Long-term toxicity to aquatic invertebrates                      NOEC              0.0038 mg/L

Toxicity to aquatic algae and cyanobacteria                          NOEC              100% saturated solution

Toxicity to microorganisms                                             NOEC              No inhibitory effect

 

The soil PNEC would be derived by application of appropriate assessment factors to the aquatic data, and the soil short-term data, and the lowest value taken. Where the substance is highly adsorptive, e.g. where the log K_ow/K_oc>5, and/or the substance is very persistent in soil, this single test should be a long-term test. Substances with a half-life >180 days are considered to be very persistent in soil.

 

Incroslip SL is not persistent, with a DT₅₀of around 28 days and has a K_ocof <5. Therefore a short-term terrestrial test is appropriate.

 

Earthworm Acute Toxicity Study (OECD 207), Klimisch 1.

 

In circumstances where less than a full soil toxicity data-set is available, both the available soil data and the EPM modified aquatic toxicity data should be used in deriving the PNECsoil. In such circumstances, where the subsequent PEC:PNEC <1, this would constitute an adequate data-set and no further testing would be required

1b: Mitigation (EPM)

Study data may not be needed to characterize the risk for soil. In defining what can be considered as sufficiency of information, it is also necessary to have all available information on water solubility, octanol/water partitioning (log K_ow), vapour pressure, and biotic and abiotic degradation, and the potential for exposure.

 

For Incroslip SL the following experimental data exist:

Water solubility                                   1.91 ×10^-5g/L

Biotic and abiotic degradationNot readily biodegradable. >50% degradation in 28 days

 

For Incroslip SL the following modelled data exist:

Vapour pressure                                1.91×10^-4

Octanol/water partitioning (log K_ow)   6.7 (max)

Adsorption Coefficient (log K_oc)         4.59-4.67*

 

When soil exposure is considered negligible, then neither a PEC, nor PNEC can or need be calculated and no soil toxicity data are necessary.

 

The potential for exposure was determined to be low. It could not be considered negligible as elimination is predominantly via the sewage treatment works and may reach the soil compartment during irrigation and waste dispersal on agricultural land.

 

*K_oc, as the solid matter partition co-efficient is considered a more reliable indicator of the potential adsorption to soil than the K_ow(octanol: water partition coefficient). The Log K_ocof Incroslip SL is below 5 (modelled data), the potential for soil adsorption is low.

 

Equilibrium Partitioning Method (EPM) Approach

Where the data available are sufficient to derive a PNEC for aquatic organisms, this PNEC can be used in a screening assessment for soil risks through the use of the EPM approach. If comparison of a PNEC_soil derived by EPM from the aquatic PNEC, shows a PEC:PNEC ratio <1, then the information available may be sufficient to conclude the soil assessment. 

 

PEC_soilderived from Simplebox (v 4.01 31 May 2015) model using the following settings and input:

 

Scenario                                                         EUSES

Case                                                               + soil depth

Chemical class                                               Amides

Molecular weight (g·mol^-1)                                283.5

Octanol/water partition coefficient (K_ow)            0.820989*

Vapour pressure (Pa)    25^oC                           0.000283*

Water solubility (mg·L^-1) 25^oC                            0.0191

 

*modelled values

 

All other values were set to default.

 

Output (regional Scale):

 

Natural soil                                                     4.73×10^-10g/kg

Agricultural soil                                              2.35×10^-10g/kg

Other soil                                                        4.73×10^-10g/kg

Total soil (PEC_soil)                                           1.181×10^-9g/kg

 

 

 

 

PNEC_waterderived from Daphnia reproductive endpoint NOEC ≥0.0038 mg/L (3.8 g/L).

 

The PEC_soil:PNEC_waterratio was calculated as follows:

 

1.181×10^-9g/kg : 3.8 g/L        =         3.108×10^-9

 

 

Where the adsorption is likely to be high, i.e. where the log K_owor Log K_oc>5, the PEC_soil:PNEC_soilratio is multiplied by 10. As Incroslip SL has a K_ocvalue close to the threshold, this safety (assessment) factor has been applied:

 

PEC_soil:PNEC_soil                   =         3.108×10^-10

 

The PEC:PNEC ratio <1 and was derived based on long-term aquatic toxicity data and included an additional safety factor. In addition, the Log K_ocis predicted to be low and biodegradation of over 50% has been observed within 28 days.

 

Furthermore, acute terrestrial toxicity data exists. The calculation of PEC_soil:PNEC_soilbased on the acute terrestrial data gives a ratio <1:

 

1.181×10^-9g/kg : 1 g/kg         =         1.181×10^-9

 

As artificial soil in the OECD 207 study contains 10% peat, a doubling safety factor should be applied:

 

1.181×10^-9· 2                        =        2.362×10^-9

 

Where the adsorption is likely to be high, i.e. where the log K_owor Log K_oc>5, the PEC_soil:PNEC_soilratio is multiplied by 10. As Incroslip SL has a K_ocvalue close to the threshold, this safety (assessment) factor has been applied:

 

PEC_soil:PNEC_soil                    =         2.362×10^-8

 

An additional safety/uncertainty factor, as the endpoint is acute and not long-term of 100 is applied:

 

2.362×10^-8·100                      =        2.362×10^-6

 

Conclusion

The EPM approach uses long-term aquatic data and factors in all safety factors required when deriving PEC:PNEC ratios for the terrestrial compartment from aquatic data. The PEC:PNEC ratio is far below the required value of 1 indicating a high margin of safety based on default PEC values set using available information. As the EPM shows no concern, there is no long-term aquatic toxicity concern and an acute terrestrial study now exists which demonstrates a NOAEC of 1000 mg/kg, no further testing is proposed.

 

Using acute terrestrial data and taking into account all safety factors required when deriving PEC:PNEC ratios for the terrestrial compartment from acute data in artificial soil. The PEC:PNEC ratio is far below the required value of 1 indicating a high margin of safety based on default PEC values set using available information. Furthermore, the earthworm covers a wide range of exposure scenarios through soil and porewater exposure.

 

No further testing is proposed.