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Short-term toxicity to fish

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Description of key information

Experimental and calculated values are used to indicate the range of toxicity expected. Data on the toxicity of alkenes to fish is available for the carbon number range C6 –C24. Two QSAR have also been run to support the experimental data (Nabholz and Mayo-Bean, 2009; DiToro et al, 2010). Acute toxicity to fish is not expected at C12 and above.

Key value for chemical safety assessment

Additional information

Wyness (1991) tested the acute toxicity of hex-1-ene to Oncorhynchus mykiss in an OECD Guideline 203 test, which included analytical monitoring of the test concentrations. Results are reported based on the mean measured exposure concentrations. The 96 hour LC50 of 5.6 mg/l is supported by a study conducted with olefins with a carbon range of C4 - C7 (Davi, 1996a) which also followed OECD Guideline 2013. Concentrations of the test substance were prepared as WAFs. The test was carried out as a semi-static renewal test and results were based on the weighted mean of the 'new' and 'old' measured exposure concentrations for each treatment. The LC50 for the test substance is 6.6 mg/l. Supporting QSAR values of 96 hour LC50 of 6.3 mg/l for hex-1-ene (Nabholz and Mayo-Bean, 2009) and 11mg/l for hexene (DiToro et al, 2010) were calculated.

Davi (1996b) investigated the toxicity of alkenes C7-9 to Oncorhynchus mykiss in an OECD Guideline 203 test. Concentrations of the test substance were prepared as WAFs. The test was carried out as a semi-static renewal test and results were based on the weighted mean of the 'new' and 'old' measured exposure concentrations for each treatment. The LC50 for the test substance is 0.87 mg/l. Supporting QSAR values of 96 hour LC50 of 1.2 mg/l for oct-1-ene (Nabholz and Mayo-Bean, 2009) and 2.1 mg/l for octene (DiToro et al, 2010) were calculated.

The toxicity of dec-1 -ene to fish was investigated in an OECD 203 test with Oncorhynchus mykiss (Brixham Environmental Laboratories, 2010a). Due to the low solubility of the test substance the test used a solvent carrier. The test substance was mixed with the solvent before being added to the dilution water. It was then stirred for 48 hours under sealed conditions to maximise the exposure concentrations. The test was carried out with sealed test vessels and the solutions were renewed daily to minimise the loss of the test substance. Measured concentrations did not remain above the solubility (0.31mg/l) throughout the exposure period in any of the test concentrations, so results are reported based on nominal loading rates. After 96 hours there were no mortalities in the blank control or solvent control. A single mortality was seen in the highest exposure concentration. These results are interpreted as demonstrating that the 96 hour LC50 of dec-1 -ene is >1.5mg/l nominal.

Davi (1996c) investigated the toxicity of alkenes C9-13 to Oncorhynchus mykiss in an OECD Guideline 203 test. Concentrations of the test substance were prepared as WAFs. The test was carried out as a semi-static renewal test and results were based on the weighted mean of the 'new' and 'old' measured exposure concentrations for each treatment. The LC50 for the test substance is 0.12 mg/l. Supporting QSAR values of 96 hour LC50 of 0.2 mg/l for dec-1-ene (Nabholz and Mayo-Bean, 2009) and 0.4mg/l for decene (DiToro et al, 2010) were calculated.

The toxicity of dodec-1 -ene to fish was investigated in an OECD 203 test withOncorhynchus mykiss(Harlan Laboratories, 2013). Due to the low solubility of the test substance the study was conducted as a limit test. A gas saturated solution was prepared by passing a steady stream of compressed air (0.5 L/minute) through a reservoir of test item and into a reservoir of test media for 48 hours to give a 100 % v/v saturated solution of the test item. The test was carried out in completely filled, sealed test vessels and the solutions were renewed daily to minimise the loss of the test substance. Measured concentrations ranged from 0.00774 mg/L to 0.0159 mg/L in the freshly prepared solutions. The concentration in the 24 hour old test media declined to 0.00266 mg/L and in the old test media from the 48, 72 and 96 hour samples, the measured concentration was less than the limit of quantification (0.00013 mg/L). After 96 hours there were no mortalities in the control or single exposure concentration. These results are interpreted as demonstrating that the 96 hour LC50 of dodec-1 -ene is greater than 0.0034 mg/L, the limit of solubility in the test media.

 The toxicity of dodec-1 -ene to fish was also investigated in an OECD 203 test with Oncorhynchus mykiss (Brixham Environmental Laboratories, 2010b). Due to the low solubility of the test substance (0.12mg/l) the study was conducted as a limit test and used a solvent carrier. The test substance was mixed with the solvent before being added to the dilution water. It was then stirred for 48 hours under sealed conditions to maximise the exposure concentrations. The test was carried out with sealed test vessels and the solutions were renewed daily to minimise the loss of the test substance. Measured concentrations remained above the solubility of the test substance throughout the exposure period (measured range 0.76 -1.5 mg/l) except during the final 24 hour period when concentrations fell from 1.1 to 0.049mg/l following the final solution renewal. After 96 hours there were no mortalities in the blank control, solvent control or single exposure concentration. These results are interpreted as demonstrating that the 96 hour LC50 of dodec-1 -ene is above its limit of solubility.

This result is supported by an OECD 203 study conducted on alkenes C10 -14 branched and linear, C12 rich (Davi, 1996d). That study was conducted as a limit test using a Water Accommodated Fraction (WAF) at a loading rate of 86mg/l. No mortality was observed after 96 hours, so the LL50 is >86mg/l WAF. Supporting QSAR values of 96 hour LC50 of 0.03 mg/l for dodec-1-ene (Nabholz and Mayo-Bean, 2009) and no toxicity expected at the limit of solubility for dodecene (DiToro et al, 2010) were calculated.

Drottar and Swigert (1995) tested the toxicity of tetradec-1 -ene to Oncorhynchus mykiss in an OECD 203 test. Due to the low solubility of the test substance test organisms were exposed to water accommodated fractions (WAF) and exposure concentrations expressed as a loading rate. The test was conducted as a limit test with a single exposure concentration of 1000mg/l WAF. No mortality was observed at this loading rate, so the 96 hour LL50 >1000mg/l WAF.

Douglas and Halls (1993) tested the toxicity of hexadec-1-ene to Oncorhynchus mykiss in an OECD 203 test. Due to the low solubility of the test substance test organisms were exposed to water accommodated fractions (WAF) and exposure concentrations were expressed as a loading rate. The test was conducted as a limit test with a single exposure concentration of 1000 mg/l WAF. No mortality was observed at this loading rate, so the 96 hour LL50 is >1000 mg/l WAF.

Christensen (1996) tested the toxicity of alkenes, C15 - 18 to Cyprinodon variegatus in an OECD 203 test. Due to the low solubility of the test substance test organisms were exposed to water accommodated fractions (WAF) and exposure concentrations were expressed as a loading rate. The test was conducted as a limit test with a single exposure concentration of 1000 mg/l WAF. No mortality was observed at this loading rate, so the 96 hour LL50 >1000mg/l WAF.

Christensen (1996) also tested the toxicity of alkenes, C16 - 18 to Cyprinodon variegatus in an OECD 203 test. Due to the low solubility of the test substance test organisms were exposed to water accommodated fractions (WAF) and exposure concentrations expressed as a loading rate. The test was conducted as a limit test with a single exposure concentration of 1000 mg/l WAF. A single mortality was observed at this loading rate, so the 96 hour LL50 is >1000 mg/l WAF.

Douglas (1993) tested the toxicity of C20 -24 alpha olefins to Oncorhynchus mykiss in an OECD 203 test. Due to the low solubility of the test substances test organisms were exposed to water accommodated fractions (WAF) and exposure concentrations expressed as a loading rate. The test was conducted using WAF prepared by the dilution of a 1000mg/l WAF stock solution. No mortality was observed at the highest loading rate of 1000 mg/l WAF, so the 96 hour LL50 >1000mg/l WAF.

Wetton (1998) tested the toxicity of alkenes, C20 -24 to Oncorhynchus mykiss in an OECD 203 test. Due to the low solubility of the test substance test organisms were exposed to water accommodated fractions (WAF) and exposure concentrations expressed as a loading rate. The test was conducted as a limit test with a single exposure concentration of 1000mg/l WAF. No mortality was observed at this loading rate, so the 96 hour LL50 >1000mg/l WAF.

Goodband and Mullee (2008) also tested the toxicity of alkenes, C20 - 24 to Oncorhynchus mykiss in an OECD 203 test. Due to the low solubility of the test substance test organisms were exposed to water accommodated fractions (WAF) and exposure concentrations were expressed as a loading rate. The test was conducted as a limit test with a single exposure concentration of 1000 mg/l WAF. No mortality was observed at this loading rate, so the 96 hour LL50 is >1000 mg/l WAF.

The experimental data indicates that toxicity to fish increases with carbon number from C6-C10, as log Kow increases. At carbon numbers above this acute toxicity is not observed at the limits of solubility. The QSAR values are in good agreement with the experimental data. Both the experimental data and Petrotox indicate that acute toxicity is not observed at C12, although Nabholz and Mayo-Bean (2009) predicts that toxicity would still be observed. As experimental data is available this is used as key, with the QSAR as supporting information.

 

The available data for C6-C12 is summarised in the table below:

·        C6 – toxicity is observed at 1 – 10 mg/l (Wyness, 1991; Davi 1996a)

·        C8 and C10 – toxicity is observed below 1 mg/l (Davi 1996b and c; Brixham Environmental Laboratories, 2010a)

·        C12 and higher – no toxicity to fish is expected (Brixham Environmental Laboratories, 2010b; Davi, 1996d; Drottar and Swigert, 1995, Harlan 2013)

Major Carbon Number

6

8

10

12

Experimental

Hex-1-ene

LC50 5.6mg/l M 

Alkenes C4-7 LC50 6.6mg/l M

Alkenes C7-9 LC50 0.87mg/l M

Dec-1-ene

LC50 >1.5mg/l N Alkenes C9-13 LC50 0.12mg/l M

Dodec-1-ene LC50 >sol 

Alkenes C10-14 LL50 >sol

ECOSAR

LC50 6.3mg/l

LC50 1.2mg/l

LC50 0.2mg/l

LC50 0.03mg/l

PETROTOX

LL50 11mg/l

LL50 2.1mg/l

LL50 0.4mg/l

LL50 >sol

M = measured. N = nominal.

At C8 and above the log Kow of the substance is above 5, the maximum log Kow within ECOSAR. These values should therefore be viewed as indicative.