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Environmental fate & pathways

Additional information on environmental fate and behaviour

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Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
other company data
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Ecotoxicity screening studies were conducted in which a biomimetic extraction technique using solid-phase microextraction (SPME) in conjunction with gas chromatography (GC) was employed to assess the level of water soluble hydrocarbons and hence the potential toxicity of the water accommodated fractions (WAFs) of the test samples. In addition, the toxicity of WAFs was also monitored using an in-vitro MicrotoxTM assay, a biosensor-based measurement system.
GLP compliance:
no
Type of study / information:
Leaching of the thickener from base oils for a range of greases

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Grease: thickener in a base oil
Details on test material:
1) Lithium soap grease (HCO/LiOH), between 10 and 15% thickener, no additives
2) Lithium-calcium mixed soap (HCO/LiOH/Ca(OH)2), between 10 and 15% thickener, no additives
3) Lithium complex soap (boric acid/HCOFA/LiOH), between 10 and 15% thickener, no additives
4) Lithium complex soap (boric acid/HCOFA/LiOH), between 10 and 15% thickener, no additives

Results and discussion

Any other information on results incl. tables

Results and Conclusions

The SPME and Microtox results for the WAFs of the grease samples at 1000 mg/L loading rate are as follows:

Grease sample SPME-GC Microtox reading
(Total peak area) (5 min) (15 min)
Lithium soap grease 489,674 >100 >100
Lithium-calcium mixed soap grease 412,232 >100 >100
Lithium complex soap 1 548,207 >100 >100
Lithium complex soap 2 512,000 >100 >100

The metal analyses were as follows:

Grease sample Calcium (mg/L) Lithium (mg/L)
Lithium soap grease <0.1 <0.1
Lithium-calcium mixed soap grease <0.1 <0.1
Lithium complex soap 1 <0.1 <0.1
Lithium complex soap 2 <0.1 <0.1

Both sets of screening data confirm that there is no apparent toxicity associated with any of the samples at the 1000 mg/L loading rate. The SPME-GC data summarised above, supported by the chromatograms, confirm that the total peak area counts are all extremely low and equivalent to background readings associated with a control sample (i.e. a WAF without any test sample added).

All of the results for calcium and lithium analysis were below the limit of detection for the method, hence all results are reported as <0.1 mg/L.

The screening ecotoxicity data (using SPME-GC and the in-vitro Microtox assay), confirm a lack of toxicity of the greases.

Applicant's summary and conclusion

Conclusions:
There is negligible leaching of the thickeners from base oils in the samples tested. The SPME-GC data confirm that the total peak area counts are all extremely low and equivalent to background readings associated with a control sample. All of the results for calcium and lithium analysis were below the limit of detection for the method, hence all results are reported as <0.1 mg/L.
Executive summary:

It was proposed that leaching studies be undertaken on thickeners in base oils to provide additional support to the grease thickener testing strategy. Information generated during the screening studies will be of relevance and value to the risk assessment of a wide range of grease thickeners and to assess the potential bioavailability of grease and other lubricant components.

The approach for the PU thickeners was to use a solid-phase microextraction (SPME) method combined with gas chromatography (GC) to assess the bioaccumulation potential of the water accommodated fractions (WAFs) of PU based grease. This approach was also used to assess the availability of the organic complexes of the metal based grease thickeners (e.g. lithium based complexes), but it was recommended that these would be complemented with metal ion analysis of the WAFs to determine whether the metal leaches out of the base grease during WAF preparation. Ecotoxicity screening studies were conducted in order to determine whether there was any toxicity associated with the grease samples. The toxicity of WAFs was monitored using an in vitro Microtox assay, a biosensor-based measurement system.

The results of the bioavailability potential of the water accommodated fractions (WAFs), the metal ion analysis and the screening ecotoxicity of lithium and calcium based complexes have been read across to aluminium based thickeners. The metal salts of fatty acids are expected to behave in a very similar manner when entrained within a grease matrix, with high temperature stability indicating that the thickener structure is robust and resistant to diffusion out of the oil. The screening ecotoxicity data (using SPME-GC and the in-vitro Microtox assay), confirm a lack of toxicity of the greases. Metal analyses confirm that there was no noticeable leaching of metal ions from the grease samples and therefore no leaching of aluminium ions would be expected either.