Naphthalenesulfonic acid, di-C9-rich C8-10-branched alkyl derivs., calcium salts

Endpoint summary

Additional information

DNNSA is the main component of calcium bis( di C8-C10, branched, C9 rich, Alkylnaphthalene sulphonate).

Hydrolysis testing for DNNSA can be used for read-across to calcium bis( di C8-C10, branched, C9 rich, Alkylnaphthalene sulphonate).

The half-life time of DNNSA at 25°C was:

t½ pH 4: > 1 year,

pH 7 > 1 year,

pH 9 > 1 year.

Calcium bis( di C8-C10, branched, C9 rich, Alkylnaphthalene sulphonate)can be expected to also have a similar rate of hydrolysis.

No data is available on photo-transformation in either water or soil.

DNNSA (di C8-C10, branched, C9 rich, alkylnaphthalene sulphonic acid) is the main component of CALCIUM BIS( DI C8-C10, BRANCHED, C9 RICH, ALKYLNAPHTHALENE SULPHONATE). Testing with DNNSA demonstrated the substance is not readily biodegradable. CALCIUM BIS( DI C8-C10, BRANCHED, C9 RICH, ALKYLNAPHTHALENE SULPHONATE) is therefore also not readily biodegradable.

The bioaccumulation of the reference substance was assessed by using a validated QSAR model which is well established and approved by the US EPA for more than a decade. As no definite measured logPOW is available for the substance (measurements resulted in >6.6, which was the upper limit of validity of the method) and this value appeared too low for a meaningful prediction of a BCF the BCF was estimated by the BCF QSAR model applying the structure and molecular weight as input, estimating a logPOW (result was 21.6) and therefrom the estimated BCF-value being 3.16. This BCF value appears reasonable as the size of the molecule (959.5 Dalton) would not led to the expectation of significant bioaccumulation and thus is taken forward for hazard and risk assessment.

As the BCF is less than 500 the substance is not considered to significantly bioaccumulate in aquatic species and in addition is not fulfilling the criteria in REACH Annex XIII for bioaccumulation.

Supporting evidence for the low bioaccumulation potential can be seen in the size of molecule (Dmax > 19 Angstroms). Molecules of this size are generally considered to have low bioaccumulation potential due to their reduced uptake and low membrane permeability.

Data on bioaccumulation in sediment or the terrestrial environment are not available.

There are experimental and QSAR approaches for the determination of the Soil Adsorption Coefficient (Koc). REACH guidance (Chapter R.7a, 2012) indicates that calculation and read-across should be the first step in estimating the Koc. No similar compounds were found which would provide read-across for Calcium DNNSA other than the corresponding Barium salt Barium DNNSA. The Guidance document (Chapter R.7a, 2012) recommends estimates be made using multiple models for a sensitivity check, therefore, a calculation of the Koc was conducted using the EPIWIN model KOCWIN and the models developed by Sabljic et al. (1995) which are described in TGD Part III (2003) and utilized by EUSES.

Results of HPLC testing (OECD 121) demonstrated the method was not suitable for Calcium DNNSA which is consistent with the guideline caution that the method may be inappropriate for surface acting compounds and low solubility "difficult substances". In accord with REACH guidance indicating that “Estimated values are essential for substances for which experimental measurement is not feasible i.e. for difficult substances”, the log Koc for DNNSA that will be used for the environmental assessment will be 5.24, the average of the 2 values estimated by modeling.