Naphthenic acids, lithium salts

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to standard test guideline OECD 203

Justification for type of information:

See IUCLID section 13 for read across justification

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

yes

Remarks:

A brief temperature excursion outside the boundaries of 22±1°C.

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Sampling: Concentrations were measured at time 0, 24-48-72 h (fresh and old) and at 96 h (old).
- Method: Aqueous sample extractions by methylene chloride with detection by Fourier transformed infrared spectroscopy (MQL= 0.6 mg/L).
- Additional characterization: GC-MS

Vehicle:

no

Details on test solutions:

- Preparation: WAFs were prepared independently by adding the appropriate amount of test substance to 4L of mineral medium and stirring for 24 ± 1 h at a speed creating a vortex of 30-50% of the depth of the solution. WAFs were prepared freshly for each daily medium renewal.
- Observations: Control and test solutions were clear and colourless with no visible signs of un-dissolved test substance, precipitate or surface film throughout the study.

Test organisms (species):

Pimephales promelas

Details on test organisms:

No details reported

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Remarks on exposure duration:

Renewal every 24 hrs

Post exposure observation period:

Not relevant

Hardness:

134 mg/L

Test temperature:

21.6-23.6°C

pH:

8-8.4

Dissolved oxygen:

7.1-9.3 mg/L

Salinity:

- Test medium: Fresh water

Conductivity:

No details reported

Nominal and measured concentrations:

- Nominal WAF loading rates: 0 (control), 1.3, 2.5, 5, 10 and 20 mg/L naphthenic acids
- Mean measured: 0 (control), 0.9, 2.08, 3.22, 6.04 and 13.8 mg/L naphthenic acids

Details on test conditions:

- Test medium: Modified well water
- Vessels: 3.8 L glass jars
- Test volume: 2 L
- 7 organisms per vessel
- Observations: Assessment of mortality, moribundity and sublethal responses were made every 24 hours (±1h).
- Conditions: Test conditions were recorded for pH and O2
- Controlled conditions: Light/dark: 16/8 (523 lux)

Reference substance (positive control):

not specified

Duration:

24 h

Dose descriptor:

LL50

Effect conc.:

> 20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LL50

Effect conc.:

ca. 11 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

ca. 9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL 6.6-12

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

> 13.8 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

ca. 7.22 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

ca. 5.62 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL 2.5-11

Duration:

96 h

Dose descriptor:

NOELR

Effect conc.:

ca. 5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: scientific judgement of the dose-response pattern

Duration:

96 h

Dose descriptor:

LOELR

Effect conc.:

ca. 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: scientific judgement of the dose-response pattern

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

ca. 3.22 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

other: scientific judgement of the dose-response pattern

Duration:

96 h

Dose descriptor:

LOEC

Effect conc.:

ca. 6.04 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Basis for effect:

other: scientific judgement of the dose-response pattern

Details on results:

Based on mortality, the 96 hour LL50 is approximately 9 mg/L and the 96 hour LC50 is approximately 5.62 mg/L.

Results with reference substance (positive control):

Not reported

Reported statistics and error estimates:

No confidence limits are reported in the HPVIS document. The 95% CL are taken from the ‘Naphthenic acids category analysis and hazard characterizaton’. Report submitted to the US EPA by the American Petroleum Institute petroleum HPV testing Group. www.petroleumhpv.org. Consortium Registration, May 14, 2012.

Validity criteria fulfilled:

yes

Remarks:

Acceptability criteria (guideline requirements) were met, except for a brief temperature excursion.

Conclusions:

The results of the study showed that WAF has lethal effects on the fish Pimephales promelas. The LLC50 is 9 mg/L and LC50 is 5.62 mg/L (measured arithmetic mean) for 96 hours of exposure.

Executive summary:

Fish mortality (species: Pimephales promelas) is evaluated during 96 hours of exposure to the water accommodated fractions (WAF) of naphthenic acids. Test was performed according to OECD TG 203, in a semi static set up with medium renewal every 24 hours. WAFs were produced with loading rates 0 (control), 1.3, 2.5, 5, 10 and 20 mg/L naphthenic acids. The measured concentrations were 0 (control), 0.9, 2.08, 3.22, 6.04 and 13.8 mg/L naphthenic acids and they were stable during the renewal period. Test conditions were suitable. There was a slight temporary deviation in temperature, but this had no further consequences. At 0, 42, 48, 72 and 96 hours, the mortalities were assessed. The results were expressed as % mortality and the effect concentrations were calculated. Analytical results are available and document exposure concentrations and stability of the test substance during the renewal period of 24 hours. The test is performed according to GLP principles and standard test procedures. The quality of the test and test results are highly reliable.

Description of key information

Lithium naphthenate consists of lithium salts of naphthenic acids. Therefore, data have been presented for both the organic anion and the lithium cation. Studies are included for naphthenic acids as well as lithium salts of docosanoic acid (C22) and dilithium adipate (C6).

Both lithium docosanoate (C22) and dilithium adipate (C6) showed 96 hour LL50/LC50 of >100 mg/L. For naphthenic acids, the 96 hour LC50 was determined to be 9 mg/L and LC50 was 5.62 mg/L (measured arithmetic mean) (HPVIS 2010a). This is supported by the other available data on naphthenic acids: the 96 hour TLm of >= 16.3 mg/L (nominal) (Cairns 1965); the 96 hour TLm of 5.6 mg/L (Cairns 1958); and 96 hour LC50 of 5 mg/L (HPVIS 2010b). Taking a worst-case approach for the results of the key studies, the short-term toxicity (96 hour LC50) of lithium naphthenate to fish is determined to be 5.62 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

5.62 mg/L

Additional information

Lithium naphthenate consists of lithium salts of naphthenic acids. Therefore, data have been presented for both the organic anion and the lithium cation. Studies are included for naphthenic acids as well as lithium salts of docosanoic acid (C22) and dilithium adipate (C6).

Lithium naphthenate is produced through the reaction of naphthenic acids with lithium hydroxide. Naphthenic acids consist of a main acidic (naphthenic) fraction (70-95%) and a smaller non-acidic (petroleum) fraction (5-30%). The acidic fraction contains typically C8-C20 with 0-3 rings and the non-acidic fraction has a carbon range mainly of C12-C22 and no single constituent >10%. The lithium hydroxide added to the naphthenic acids will neutralise the components within the acid fraction to form lithium salts while any components present in the non‑acidic fraction of naphthenic acids (the unsaponifiable matter) will be unchanged by the manufacturing process. Therefore, lithium naphthenate is expected to consist of 70 - 95% lithium salts of naphthenic acids (C8-C20, 0-3 rings), with 5 - 30% unsaponifiable matter unchanged from the naphthenic acids starting material.

Dilithium adipate (C6) has a shorter chain length than the acids present in lithium naphthenate (C8) and is a dicarboxylic acid, while fatty acids present in lithium naphthenate are monocarboxylates. Although no dicarboxylic acid salts were identified in the GC-MS analysis for lithium naphthenate, the dataset for dilithium sebacate shows that the substance follows similar trends in properties to the longer chain monocarboxylic acid lithium salts and supports the read across between lithium salts of different carboxylic acids. Dilithium adipate, as a lithium salt of a carboxylic acid two shorter than those present in lithium naphthenate, presents a worst-case scenario for the shortest chain length present in the target substance, bracketing one end of the range of potential properties of constituents present in the UVCB.

Lithium docosanoate (C22) has a longer chain length as the longest chain length acids present in the acidic fraction of lithium naphthenate (C20). Therefore, lithium docosanoate, as a lithium salt of a carboxylic acid two longer than those present in lithium naphthenate, bracket the other end of the range of potential properties of constituents present in the UVCB.

HPVIS (2010a)

HPVIS evaluated fish mortality (species:Pimephales promelas) during 96 hours of exposure to the water accommodated fractions (WAF) of naphthenic acids. Test was performed according to GLP principles and OECD TG 203, in a semi static set up with medium renewal every 24 hours. The results of the study showed that the WAF had lethal effects on the fishPimephales promelas. The LLC50 is 9 mg/L and LC50 is 5.62 mg/L (measured arithmetic mean) for 96 hours of exposure.

Harlan (2013)

Lithium docosanoate, a lithium salt of C22 straight chain monocarboxylic acid, is a structural analogue for the representative constituent “Acidic fraction, lithium salt of C20, 0 rings”. The data for lithium docosanoate have been read across to lithium naphthenate.

The acute toxicity of lithium docosanoate to fish was determined in a GLP-compliant, limit test (Harlan 2013) following OECD guideline 203. Seven fish were exposed to a single concentration of lithium docosanoate for 96 hours in a semi-static freshwater study and any effects were recorded. The acute toxicity of lithium docosanoate to fish showed no effects at a water accommodated fraction loading rate of 100 mg/L WAF so the 96 hour LC50 is determined to be > 100 mg/L WAF.

WIL (2015)

Dilithium adipate, a lithium salt of C6 straight chain dicarboxylic acid, is a structural analogue for the representative constituent “Acidic fraction, lithium salt of C8, 0 rings”. The data for dilithium adipate have been read across to lithium naphthenate.

The effect of dilithium adipate on the mortality of the carp (Cyprius carpio) was investigated according to an OECD 203 guideline and EC method C1 study. A 96 hour limit test at 100 mg/L was conducted under static conditions. The test concentrations were considered to be maintained and the results are reported based on nominal concentrations. As no fish mortalities were observed in the test the LC50 is > 100 mg/L dilthium adipate.

Cairns (1965)

The acute toxicity of naphthenic acids to fish was taken from published literature (Cairns 1965). The test was conducted under referenced test conditions current for the period in which the study was run. Fish were exposed to naphthenic acids for 96 hours and the 96 hour TLm (median tolerance limit) for fish was determined to be >= 16.3 mg/L (nominal) based on mortality.

Cairns (1958)

The mortality threshold limit, along with the highest and lowest threshold limit, for the short-term (96 hour) toxicity of naphthenic acids to fish (Lepomis macrochirus) was taken from published literature. The test was conducted under referenced test conditions current for the period in which the study was run. The study was performed prior to the adoption of the test guideline OECD Guideline 203 (Fish, Acute toxicity test) but followed standard scientific principles. The 96 hour-TLm (mortality threshold limit, equivalent to an LC50) value forLepomis macrochirushas been experimentally determined for naphthenic acid solutions to be 5.6 mg/L. There was 0% survival at the highest threshold concentration of 7 mg/L and 100% survival at the lowest threshold concentration of 3.5 mg/L.

HPVIS (2010b)

The acute toxicity of naphthenic acids to fish was taken from published literature (HPVIS 2010), citing an earlier study (Dom 1992). The study followed standard scientific principles (Peltier and Weber 1985) but limited details were reported in the regulatory summary document. The study has been assigned a Klimisch score of 3, not reliable, as a statistically-defined LC50 was not calculated and water chemistry data were not reported. The LC50 of naphthenic acid toGasterosteus aculeatuswas determined to be approximately 5 mg/L.

Conclusion

Lithium naphthenate consists of lithium salts of naphthenic acids. Therefore, data have been presented for both the organic anion and the lithium cation. Studies are included for naphthenic acids as well as lithium salts of docosanoic acid (C22) and dilithium adipate (C6). Both lithium docosanoate (C22) and dilithium adipate (C6) showed 96 hour LL50/LC50 of >100 mg/L. For naphthenic acids, the 96 hours LC50 was determined to be 9 mg/L and LC50 was 5.62 mg/L (measured arithmetic mean) (HPVIS 2010a). This is supported by the other available data on naphthenic acids: the 96 hour TLm of >= 16.3 mg/L (nominal) (Cairns 1965); the 96 hour TLm of 5.6 mg/L (Cairns 1958); and 96 hour LC50 of 5 mg/L (HPVIS 2010b). Taking a worst-case approach for the results of the key studies, the short-term toxicity of lithium naphthenate to fish is determined to give a 96 hour LC50 5.62 mg/L and a 96 hour LL50 of 9 mg/L.