Naphtha (Fischer-Tropsch), light, C4-10-branched and linear

Endpoint summary

Description of key information

Acute toxicity:

-(96h) LL50 for freshwater fish rainbow trout (Oncorhynchus mykiss): >100 mg/l (WAF, nominal, based on mortality) [OECD 203; test mat. C4-C10 branched and linear hydrocarbons (light) – Naphtha]

-(48 h) EL50 for Daphnia magna (freshwater): > 18 < 32 mg/l (WAF, nominal, based on immobilisation) [OECD 202; test mat. C4-C10 branched and linear hydrocarbons (light) – Naphtha]

-(72 h) EL50 for Pseudokirchneriella subcapitata: > 100 mg/l (WAF, nominal, based on: growth rate) [OECD 201; test mat. C4-C10 branched and linear hydrocarbons (light) – Naphtha]

Chronic toxicity:

-(33 d) NOEL rate for freshwater fish fathead minnow (Pimephales promelas): 100 mg/l (WAF, nominal, based on:fish length and dry weight) [OECD 210; test mat. C4-C10 branched and linear hydrocarbons (light) – Naphtha]

-(21 d) NOEL rate for Daphnia magna (freshwater): 22 mg/l (WAF, nominal, based on immobilisation) [OECD 211; test mat. 'C4-C10 branched and linear hydrocarbons (light) – Naphtha]

Additional information

Acute Toxicity

The following key studies with C4-C10 branched and linear hydrocarbons (light) – Naphtha (CAS 848301-65-5) were available:  

Short-term toxicity to fish

The acute toxicity of the registered substance to the freshwater fish rainbow trout (Oncorhynchus mykiss) has been investigated and gave a 96-Hour LL50 value > 100 mg/l loading rate WAF. Correspondingly the No Observed Effect Loading rate was 100 mg/l loading rate WAF. Finally, there were no sub-lethal effects of exposure observed in 14 fish exposed to a 100 mg/l loading rate WAF for a period of 96 hours. With regard to the water solubility, the test item is considered to have no acute toxic effects to fish at the water solubility limit (saturation).  

Short-term toxicity to aquatic invertebrates

The acute toxicity of the registered substance to the freshwater invertebrate Daphnia magna has been investigated and gave a 48-Hour EL50 value in the range of 18 - 32 mg/l loading rate WAF. The No Observed Effect Concentration at 48 hours was 10 mg/l loading rate WAF, based upon no significant immobilisation at this concentration. TOC analysis showed that the concentration of the test item in solution was < limit of quantitation, which was considered to be 1.0 mg C/l.

Toxicity to aquatic algae and cyanobacteria

Exposure of Pseudokirchneriella subcapitata to the registered substance gave EL50 (72 h) values of greater than 100 mg/l loading rate WAF and correspondingly the No Observed Effect Loading Rate (72 h) was 100 mg/l loading rate WAF. Total Organic Carbon (TOC) analysis of the test preparations prepared with the omission of algal cells was performed at 0 and 72 hours.  

Supporting studies

There are studies from the IUCLID dataset (2000) of ‘Naphtha (petroleum), light alkylate’ (CAS 64741-66-8) available, which is a near analogue to 'Naphtha (Fischer-Tropsch), light, C4 -10 - branched and linear' :  

- Acute toxicity of 'Alkylate naphtha' to aquatic invertebrates; based on the missing identifier "CAS number" in the IUCLID dataset the substance identity was not clear - there are two possibilities:

a) Naphtha (petroleum), heavy alkylate [CAS No. 64741-65-7], which is defined as: 'A complex combination of hydrocarbons produced by distillation of the reaction products of isobutane with monoolefinic hydrocarbons usually ranging in carbon numbers from C3 to C5. It consists of predominantly branched chain saturated hydrocarbons having carbon numbers predominantly in the range of C9 through C12 and boiling in the range of approximately 150°C to 220°C (302°F to 428°F).' --> test substance is slightly comparable to 'Naphtha (Fischer-Tropsch), light, C4-10 - branched and linear'.

b) Naphtha (petroleum), light alkylate [CAS No. 64741-66-8], which is defined as: 'A complex combination of hydrocarbons produced by distillation of the reaction products of isobutane with monoolefinic hydrocarbons usually ranging in carbon numbers from C3 through C5. It consists of predominantly branched chain saturated hydrocarbons having carbon numbers predominantly in the range of C7 through C10 and boiling in the range of approximately 90°C to 160°C (194°F to 320°F).' --> test substance is comparable to 'Naphtha (Fischer-Tropsch), light, C4-10 - branched and linear'.

Result: The LC50 (48h) of the test substance 'Alkylate naphtha' to aquatic invertebrates was calculated to be 2 mg/l, the NOEC (48h) was calculated to be 0.56 mg/l; the 24h- and 96h-LC50 values were 7.9 and 4.2 mg/l respectively [supporting study: ‘Short-term toxicity to aquatic invertebrates, R86/326a].  

- Acute toxicity of ‘Naphtha (petroleum), isomerization’ [CAS No. 64741-70-4] to aquatic invertebrates; it is defined as: 'A complex combination of hydrocarbons obtained from catalytic isomerization of straight chain paraffinic C4 through C6 hydrocarbons. It consists predominantly of saturated hydrocarbons such as isobutane, isopentane, 2,2-dimethylbutane, 2-methylpentane, and 3-methylpentane' --> the test substance is slightly comparable to 'Naphtha (Fischer-Tropsch), light, C4-10 - branched and linear'.

Result: The EL50 (48h) of the test substance 'Naphtha (petroleum), isomerization' to aquatic invertebrates was calculated to be 10 mg/l with a 95% confidence interval of 13 to 18 mg/l. The NOEL (48h) was calculated to be 5.0 mg/l, but the observed value was 0.5 mg/l [supporting study: ‘Short-term toxicity to aquatic invertebrates, 104542].  

- Toxicity of ‘Alkylate naphtha’ to aquatic plants e.g. algae; based on the missing identifier "CAS number" in the IUCLID dataset the substance identity was not clear - probably the test substance has the CAS No. 64741-70-4 and is defined as: 'A complex combination of hydrocarbons obtained from catalytic isomerization of straight chain paraffinic C4 through C6 hydrocarbons. It consists predominantly of saturated hydrocarbons such as isobutane, isopentane, 2,2-dimethylbutane, 2-methylpentane, and 3-methylpentane.' --> the test substance is slightly comparable to 'Naphtha (Fischer-Tropsch), light, C4-10 - branched and linear'.

Result: The NOEC (72h) of the test substance 'Naphtha (petroleum), isomerization' to aquatic algae was calculated to be 0.1 mg/l and the EC50 (72h) was calculated to be 13 mg/l) [supporting study: ‘Toxicity to aquatic algae and cyanobacteria.002’].  

Conclusion on acute toxicity

No adverse effects were observed in acute fish and algae toxicity tests. In the key study with invertebrates, the most sensitive species was Daphnia magna with EL50 values in the range of 18 - 32 mg/l loading rate WAF. In this study, the presence of the registered substance was investigated by a total organic carbon (TOC) analysis. After 0 h, TOC was measured at every concentration (10 -100 mg/L nominal loading rate), whereas after 48 h the concentration of TOC was below the limit of quantitation in the concentration range from 10 up to 100 mg/L nominal loading rate. The authors of the report conclude that this does not infer that no test item was in solution just that which was present was so at a concentration of less than 1.0 mg C/l. Nevertheless, the result did not provide definitive evidence of the presence of test item. Therefore, two additional supporting studies with read-across substances were used for the hazard assessment and for the classification. According to the "Guidance on the Application on the CLP Criteria" the available acute toxicity data is sufficient and the test item C4 -C10 branched and linear hydrocarbons (light) - Naphtha (CAS 848301 -65 -5) does not have to be classified as an acute (short-term) aquatic hazard.

Chronic Toxicity

The following key studies with C4-C10 branched and linear hydrocarbons (light) – Naphtha (CAS 848301-65-5) were available:  

Long-term toxicity to fish

Due to the results it was considered that the registered substance had no effect on the survival or growth of newly laid eggs of fathead minnows (Pimephales promelas). The "Lowest Observed Effect Loading Rate" (LOEL), based on nominal loading rates, was considered to be > 100 mg/l loading rate WAF on the basis that there were no significant decreases (P>0.05) in terms of fish length and dry weight when compared to the control at the end of the test. The "No Observed Effect Loading Rate" (NOEL), based on nominal loading rates, was considered to be 100 mg/l loading rate WAF on the basis that there were no significant decreases (P>0.05) in terms of fish length and dry weight when compared to the control at the end of the test. With regard to the water solubility, the test item is considered to have no chronic toxic effects to fish at the water solubility limit (saturation).  

Long-term toxicity to aquatic invertebrates

The observed mortalities in the parental group in the 0.70, 2.2, 7.0 and 22 mg/l loading rate WAF test groups were not significantly different (P>0.05) when compared to the control group. The 21-Day EL50 (immobilisation) value, based on nominal loading rates, for the parental Daphnia generation (Pi) was estimated to be > 22 mg/l loading rate WAF. No significant impairment of reproduction was observed at the loading rates employed during the test. The 21-Day EL50 (reproduction) based on nominal loading rates was > 22 mg/l loading rate WAF. The "Lowest Observed Effect Loading rate" (LOEL) based on nominal loading rates was considered to be > 22 mg/l loading rate WAF and the "No Observed Effect Loading rate" (NOEL) was considered to be 22 mg/l loading rate WAF.  

Conclusion on chronic toxicity

No significant chronic toxicity was observed in Fish Early Life Stage study undertaken on the "Naphtha (Fischer-Tropsch), light, C4 -C10 - branched and linear". The most sensitive species was Daphnia magna. The 21-Day EL50 (immobilisation) value, based on nominal loading rates, for the parental Daphnia generation (P1) was estimated to be greater than 22 mg/l loading rate WAF. The 21-Day EL50 (reproduction) value based on nominal loading rates was estimated to be greater than 22 mg/l loading rate WAF. The "Lowest Observed Effect Loading rate" was considered to be greater than 22 mg/l loading rate WAF on the basis that at this loading rate no significant mortalities (immobilisation) were observed in the parental generation (P1) and that there were no significant differences (P>0.05) between the control and the 22 mg/l loading rate WAF test group in terms of numbers of live young produced per adult by Day 21. The "No Observed Effect Loading rate" was considered to be 22 mg/l loading rate WAF on the basis that at this loading rate there were no significant mortalities (immobilisation) observed in the parental generation (P1) and that there were no significant differences (P>0.05) between the control and the 22 mg/l loading rate WAF test group in terms of numbers of live young produced per adult by Day 21. Using the OECD Category approach the available chronic toxicity data of "Naphtha (Fischer-Tropsch), light, C4 -C10 - branched and linear" is considered to be sufficient to provide a weight of evidence that the registered substance has limited chronic toxicity i.e. insufficient to classify as hazardous for the environment according to CLP criteria.