Naphthenic acids, lithium salts

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE: MPBPVP v1.43 (2010)

2. MODEL (incl. version number): EPI Suite Version 4.11 (2012)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See QPRF

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Lithium naphthenate is a UVCB consisting of a large number of different constituents. Bioconcentration factor values have been predicted for representative structures within the UVCB.

Principles of method if other than guideline:

- Software tool(s) used including version: BCFBAF v3.01
- Model(s) used: EPISuite V4.11 (2012)

GLP compliance:

no

Specific details on test material used for the study:

Lithium naphthenate consists of 70-95% lithium salts of naphthenic acids, C8-C20 and 0-3 rings, and 5-30% petroleum fraction, C12-C22, which remains unreacted from the naphthenic acid raw material. Lithium naphthenate is a UVCB containing a large number of constituents, each of which could potentially have properties varying from other constituents in the salt. Therefore, QSAR predictions have been provided for representative structures which bracket the range of potential constituents present in lithium naphthenate with regard to the molecular weight and number of cyclic groups. For further details, see QPRF.

- Representative constituent: Acidic fraction, lithium salt of C8, 0 rings
- SMILES: CCCCCCCC(=O)O([Li])

- Representative constituent: Acidic fraction, lithium salt of C8, 1 rings
- SMILES: [Li]OC(=O)CC1CCCCC1

- Representative constituent: Acidic fraction, lithium salt of C8, 2 rings
- SMILES: [Li]OC(=O)C1CC2C(CCCC2)CC1

- Representative constituent: Acidic fraction, lithium salt of C15, 3 rings
- SMILES: [Li]OC(=O)C1CC2C(CC3C(CCCC3)C2)CC1

- Representative constituent: Acidic fraction, lithium salt of C20, 0 rings
- SMILES: CCCCCCCCCCCCCCCCCCCC(=O)O([Li])

- Representative constituent: Acidic fraction, lithium salt of C20, 1 rings
- SMILES: [Li]OC(=O)CCCCCCCCCCCCCC1CCCCC1

- Representative constituent: Acidic fraction, lithium salt of C20, 2 rings
- SMILES: [Li]OC(=O)CCCCCCCCCC1CC2C(CCCC2)CC1

- Representative constituent: Acidic fraction, lithium salt of C20, 3 rings
- SMILES: [Li]OC(=O)CCCCCC1CC2C(CC3C(CCCC3)C2)CC1

- Representative constituent: Petroleum fraction, C12
- SMILES: CCCCCCCCCCCC

- Representative constituent: Petroleum fraction, C22
- SMILES: CCCCCCCCCCCCCCCCCCCCCC

Radiolabelling:

not specified

Vehicle:

not specified

Test organisms (species):

not specified

Route of exposure:

aqueous

Justification for method:

other: QSAR

Test type:

not specified

Water / sediment media type:

not specified

Reference substance (positive control):

not specified

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

3.162 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Acidic fraction, lithium salt of C8, 0 rings

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

3.162 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Acidic fraction, lithium salt of C8, 1 rings

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

3.162 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Acidic fraction, lithium salt of C8, 2 rings

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

3.162 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Acidic fraction, lithium salt of C15, 3 rings

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

3.162 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Acidic fraction, lithium salt of C20, 0 rings

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

10 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Acidic fraction, lithium salt of C20, 1 rings

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

56.23 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Acidic fraction, lithium salt of C20, 2 rings

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

56.23 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Acidic fraction, lithium salt of C20, 3 rings

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

207.7 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Petroleum fraction, C12

Temp.:

20 °C

pH:

7

Type:

BCF

Value:

31.34 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Representative constituent: Petroleum fraction, C22

Details on results:

Standard conditions assumed
The BCF of the represenative constituents of lithium naphthenate are estimated by QSAR to be in the range of 3.162 to 207.7 L/kg ww.

Validity criteria fulfilled:

not specified

Conclusions:

The BCF of the representative constituents of lithium naphthenate are estimated by QSAR to be in the range of 3.162 to 207.7 L/kg ww.

Executive summary:

The BCF of the representative structures of lithium naphthenate were estimated using a QSAR model (BCFBAF v3.01 in EPISuite v4.11, US EPA 2010).

Description of key information

 Lithium is expected to have a low potential for bioaccumulation, with a BCF of around 8 L/kg in freshwater fish. The BCF of the representative constituents of lithium naphthenate are estimated by QSAR to be in the range of 3.162 to 207.7 L/kg ww. Therefore, lithium naphthenate is considered not to bioaccumulate in the aquatic environment.

Additional information

No data are available for the bioconcentration in aquatic species of the lithium naphthenate. The bioaccumulation endpoint can be waived if the substance has a low potential for bioaccumulation, as indicated by a log Kow of less than 3. However, due to the surface active nature of the substance, the octanol-water partition coefficient could not be measured. It was not possible to measure the water solubility of the substance as it is not truly soluble in water but forms a stable dispersion instead and it is therefore expected that the substance has limited bioavailability. Furthermore, in realistic use scenarios, the thickener will be contained in base oil, with the formulated greases specifically designed to minimise the leaching of the thickener. Therefore, during use, the concentrations of the substance which would be bioavailable are further limited.

Lithium naphthenate, which consists of a lithium cation and a naphthenic acid anion, is a UVCB substance with a large number of constituents. Lithium naphthenate consists of 70-95% lithium salts of naphthenic acids, C8-C20 and 0-3 rings, and 5-30% petroleum fraction, C12-C22, which remains unreacted from the naphthenic acid raw material. Lithium naphthenate is a UVCB containing a large number of constituents, each of which could potentially have properties varying from other constituents in the salt. Therefore, QSAR predictions have been provided for representative structures which bracket the range of potential constituents present in lithium naphthenate with regard to the molecular weight and number of cyclic groups. The BCF of the representative structures of lithium naphthenate were estimated using a QSAR model (BCFBAF v3.01 in EPISuite v4.11, US EPA 2010).

Furthermore, data are presented separately for the bioaccumulation of the lithium ion. Barber et al. (2006) provide a BCF for lithium in Gambusi (whole body) of 5 L/kg and in Tilapia of 2 L/kg (fillet) and 8 L/kg (liver). The bioconcentration factor of lithium in two species of fish, Gambusi and Tilapia, was determined in a non-GLP, non-guideline study published in a peer-reviewed journal. The study measured the lithium concentration in constructed secondary effluent wastewater wetlands and the lithium concentration in whole Gambusia and the fillets and livers of Tilapia fish living in the wetlands and used the data to calculate a bioconcentration factor for lithium in freshwater fish. There are limitations in design and/or reporting, but the study follows sound scientific principles and is considered reliable and relevant for use for this endpoint.

Karlsson et al. (2002) provide a bioaccumulation factor for lithium of 1 in the edible parts of marine and freshwater fish, citing data from the National Council on Radiation Protection and Measurements, USA (NCRP, 1996). No further information on the source of the data, the review or evaluation of the data or the choice of value is provided. However, they note that a 10-fold error is likely according to a review of other available data. Even so, the BAF reported are very low.

Although, Pokorska et al. (2012) do not directly provide any information on bioconcentration factors, they do indicate that the mean lithium concentrations in muscles, kidney and liver of flounder obtained from the South Baltic sea are 0.017 ± 0.007 mg/kg wwt, 0.044 ± <0.001 mg/kg wwt and 0.010 ± 0.009 mg/kg wwt, respectively. The concentrations in Baltic herring were determined to be 0.010 ± 0.010 mg/kg wwt for muscles and 0.015 ± <0.001 mg/kg wwt for liver, though the concentration in the kidneys was not determined. The concentration of lithium in flounder and herring was determined in a non-GLP-compliant, non-guideline study, published in a peer-reviewed journal. Flounder and herring (twenty of each species) were collected from the southern Baltic Sea, the muscles, liver and kidneys digested separately and the lithium content determined by ICP-AES. There are limitations in design and/or reporting, but the study is otherwise considered adequate for assessment. Using a lithium concentration in seawater of 170 to 190 µg/L (Aral and Vecchio-Sadus 2008), the bioconcentration factors were all calculated to be below 1.

The bioaccumulation of lithium in largemouth yellowfish and their parasitic worms was determined in a non-GLP-compliant, non-guideline study, published in a peer-reviewed journal (Retief 2009). Twenty largemouth yellowfish (Labeobarbus kimberleyensis), along with water and sediment samples, were collected from Vaal Dam, South Africa. The muscle, spinal cord, liver and intestinal parasites were digested separately and the lithium concentration in each of the samples was determined by ICP-MS. No significant difference was observed when the lithium concentrations in water and sediment were compared to the liver, muscle, spinal cord of largemouth yellowfish (Labeobarbus kimberleyensis) and tapeworms (Bothriocephalus acheilognathi), indicating that lithium is not bioaccumulated. There are limitations in design and/or reporting, but the study is otherwise considered adequate for assessment.

In a study by Retief et al. (2006), lithium was not accumulated in the liver, muscle or spine of fish (Labeobarbus kimberleyensis) collected from a South African reservoir, indicating that BCF value would be very low. However, it was observed to accumulate in parasitic worms found in the guts of these fish. No BCF values were calculated, and the lithium concentration in the water was not reported. The parasites would have been exposed to lithium in the gut of the fish, rather than the water to which the fish were exposed, further complicating any calculation of BCF values. The lithium concentration in the parasites was approximately 0.036 μg/g (wwt). A typical range of lithium concentrations in freshwaters has been reported by Aral and Vecchio-Sadus (2008) as 0.07 to 40 μg/L. Using these values, a range of BCF values can be estimated (based on the exposure of the fish within which the parasites were present). Following this approach, a range of BCF values can be calculated from 0.9 to 514. Using the geometric mean of the minimum and maximum lithium concentrations in surface waters (1.7 μg/L) a generic BCF value of 21.5 is calculated.

Although none of these studies follow standard guidelines, the available data indicate that the lithium component of lithium naphthenate is expected to have a low bioaccumulation factor. Taken together with the QSAR estimates for the representative structures of lithium naphthenate being in the range of 3.162 to 207.7 L/kg, the substance is not considered to bioaccumulate in the aquatic environment and subsequently are not expected to pose a risk of secondary poisoning.

References

Aral H, Vecchio-Sadus A (2008) Toxicity of lithium to humans and the environment – A literature review. Ecotoxicology and environmental safety, vol. 70, pp. 349-356

NCRP, 1996. Screening models for releases of radionuclides to atmosphere, surface water, and ground. NCRP report No. 123 I. National Council on Radiation Protection and Measurements, USA cited in Karlsson (2002)