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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

The substance displays properties that indicate persistency within the environment, based on low ready biodegradability. Due to the inorganic elements in the chemical structure, the substance can never readily biodegrade. Furthermore, due to the extremely low water solubility, the hydrolysis of the substance cannot be measured although the chemical structure would suggest that hydrolysis is unlikely to occur.

As such, the substance fulfils the requirements of Annex XIII, Para 1.1 based on evaluation of available data, and can be considered to be “P” based in this data.

 

The weight of evidence presented below on calcium sulfonates demonstrates that CLP/GHS classification as hazardous to the aquatic environment is not justifiable and that the hazard profile does not meet the B or vB criteria. This assessment should apply to all calcium sulfonates whether natural or synthetic, whether high or low TBN and may also apply to other alkyl benzene sulfonates (e.g., Mg, Na) based on further evaluation.

Measured log kow is challenging to complete accurately as the substance is stable in mineral oil affecting the accuracy of the method. The available experimental undertaken on alkyl benzene sulfonate substances result in limit values in the range >4.46 to >6.7. Where a measured Log Kow has been achieved, the log Kow is 10.

The Log Kow of the substance and similar related alkyl benzene sufonate acids and salts have been estimated using recognised QSAR estimation tool. Using a range of mono and di- linear alkyl benzene sulfonates the log Kow has been estimated in a range 14 – 31. 

While the modelling of Log Kow values greater than 10 is uncertain, on the basis of the weight of evidence of measured and modelled data, the log Kow of the substance is generally considered >6 suggesting a tendency to a reduced BCF.

An assessment of the propensity towards bioaccumulation was undertaken using recognised QSAR derivation tools. The BCF for linear alkyl benzene sulfonates has been assessed by

            BCF model (Meylan) (version 1.0.0)

            BCF model (CAESAR) (version 2.1.11)

            US EPA On-Line EPI Suite™v4.0 model BCFBAF

On the basis of these QSAR assessments, the BCF for the substance is in the range 11 - 70.89.

In addition, review of data published by the WHO Task Group on Environmental Health demonstrates a whole body BCF ≤20

Ref:

Wakabayashi M, Kikuchi M, Kojima H, & Yoshida T (1980) Effect of alkyl    chain on the uptake, distribution, and excretion of35-labelled alkyl sulfates in carp. Ecotoxicol Environ Saf, 4: 195-206.

 

Wakabayashi M, Kikuchi M, Sato A, & Yoshida T (1981) [The relationship   between exposure concentration and bioaccumulation of surfactants.]Bull Jpn Soc Sci Fish, 47: 1383-1387 (in Japanese).

 

Calcium sulfonate: Read Across to similar structures with experimental BCF; Japan CHRIP database presents 3 similar substances (CAS#81-11-8; 88-44-8; 121-03-9) with experimental BCF values in carp of <5

On the basis of a weight of evidence approach for log kow and BCF, there is sufficient information available to state that the substance is not bioaccumulative. The BCF for the substance is predicted to be low on the basis of the estimated log kow being >6. Furthermore, the estimated BCF for the substance is ≤70.89 and available data for chemically similar products demonstrate a BCF below 70. The substance does not fulfil the requirement of Annex XIII, Para 1.2 based on evaluation of available data, and cannot be considered to be “B” or “vB” based on the available data. 

The LC50 in freshwater fish is considered to be >1000mg/l and >10000 mg/l with marine species. The substance is, therefore, considered not toxic to freshwater or marine fish species. Nevertheless, adequate controls will be in place during production and use to ensure that the substance is not released to the environment.

The EC50 in freshwater Daphnia is considered to be >1000mg/l. The substance is, therefore, considered not toxic to Daphnia magna. Nevertheless, adequate controls will be in place during production and use to ensure that the substance is not released to the environment.

The toxicity of the substance has not been assessed using marine invertebrate species, but it is considered likely to be similar to freshwater species.

The EC50 in freshwater algae is considered to be >1000mg/l. Two of the studies available support this conclusion, while the one remaining study did not exceed 100 mg/l, although the data support the conclusion that the EC50 is above this dose level. As this dose level has been included in the other studies conducted, it is considered acceptable to consider this as supporting data but to conclude that the highest dose level attained from studies considered reliable is both appropriate and adequately supported by the data.

The substance is highly water insoluble, so toxicity has been assessed on the bioavailable fraction of the substance based using Water Accommodated Fractions.

All of the study data available to assess the mutagenic, clastogenic and genotoxic effects of the substance in vitro and in vivo indicate a lack of mutagenic response, achieving negative responses at all endpoints. 

The data available to assess reproduction toxicity also demonstrate a lack of response to parent and F1 animals with no effects on reproduction.

On the basis of the genetic and reproduction toxicity data available, in addition to the repeated dose toxicity data the substance is considered to not present the potential for carcinogenic hazard. No additional data are therefore proposed and the substance is not classified for this endpoint.

Data from two 28-day oral toxicity studies are available with exposure by oral gavage to linear and branched alkyl benzene sulphonates upto a maximum dose of 1000 mg/ml/day. Relatively slight effects were observed in either study, limited to a reduction in cholesterol in serum at high dose animals only in one study. The lowest dose at which no adverse effects were observed effects were observed is, therefore, taken as the appropriate effect level. NOAEL=500mg/kg/day

The data from only one 28-day toxicity test by the inhalation route is available. The test substance is, however, extremely difficult to test by this route and, due to the nature of the substance in mineral oil, any effects due to the test sample are masked by the effects of the mineral oil. The NOAEC is, therefore, determined by extrapolation to oral exposure. NOAEC = 881.58 mg/m3

The data from two 28-day dermal toxicity studies are available to assess dermal toxicity by repeated dose. No systemic toxicity was observed in either study. NOEL = 1000 mg/kg/day

On the basis of the data available, the substance is not unduly toxic to freshwater or marine species and is also not considered to be a CMR. In addition, the data available from sub-acute toxicity testing shows the substance to be not toxic to mammalian species and provides no justification or concern for sub chronic testing. The substance does not fulfil the requirement of Annex XIII, Para 1.3 based on evaluation of available data, and cannot be considered to be “T”. 

Likely routes of exposure:

The neat substance would be manufactured and formulated products containing the substance would be produced in closed systems. Furthermore, the substance can never be isolated from a mineral oil solvent that is essential to maintain the structural equilibrium of the substance. Removal of this solvent would degrade the chemical structure from the structure of the registered substance.

By QSAR analysis, the substance is anticipated to be a solid with an extremely low vapour pressure. Furthermore, its physical state in the solvent is a highly viscous liquid. The substance is not, therefore, expected to be readily available to the air at ambient conditions.

Nevertheless, recommendations for handling and disposal would be made that are intended to avoid exposure of the substance to the various compartments of the environment during the whole lifecycle of the substance. Controls recommended on the product lifecycle are specifically intended to avoid emission of the substance to air. The neat substance would be manufactured and formulated products containing the substance would be produced in closed systems. Furthermore, the substance can never be isolated from a mineral oil solvent that is essential to maintain the structural equilibrium of the substance. Removal of this solvent would degrade the chemical structure from the structure of the registered substance.

By QSAR analysis, the substance is anticipated to be a solid with an extremely low vapour pressure. Furthermore, its physical state in the solvent is a highly viscous liquid. The substance is not, therefore, expected to be readily available to the air at ambient conditions.

Nevertheless, recommendations for handling and disposal would be made that are intended to avoid exposure of the substance to the various compartments of the environment during the whole lifecycle of the substance. Controls recommended on the product lifecycle are specifically intended to avoid emission of the substance to air.