Paraffin waxes (Fischer-Tropsch), isomerization

Endpoint summary

Description of key information

- since hydrocarbons with carbon numbers >C50 are considered too hydrophobic and immobile to cause significant aquatic toxicity, it is considered justified to use data of the closely related substance GTL base oil (C18-50; CAS 848301-69-9, EC 482-220-0) covering the entire low molecular weight fraction of the registration substance up to C50;

- the toxicity of the registration substance containing higher molecular weight constituents (C25-150 , about 30-55 % >C50) to aquatic organisms can also be expected to be non-toxic to aquatic organisms and with no effects at the water solubility limit (saturation), based on reliable aquatic toxicity data for GTL base oil;

- all available aquatic toxicity data on related substances indicate that the registration substance 'Paraffin waxes (Fischer-Tropsch), isomerization' is unlikely to exhibit acute or chronic toxicity to aquatic organisms.

Additional information

Measured aquatic toxicity data are not available for the registration substance 'Paraffin waxes (Fischer-Tropsch), isomerization'.

However, reliable data are available for the closely related substance GTL base oil (C18-50; CAS 848301-69-9, EC 482-220-0), which can cover the entire low molecular weight fraction of the registration substance up to C50. 

Since hydrocarbons with carbon numbers >C50 are considered too hydrophobic and immobile to cause significant aquatic toxicity, the study results of GTL base oil - consisting of linear and branched alkanes (paraffins) with a small amount of cycloalkanes in the carbon range from C18 to C50 - are considered to represent the maximum achievable toxicity of the registration substance (C25-150, about 30-55% >C50) to aquatic organisms.

 

Short-term toxicity to fish (OECD 203)

The test results, expressed as the LL₅₀ value, showed that the closely related substance GTL base oil was not acutely toxic to fish at a loading rate of 1000 mg/l.

 

Long-term toxicity to fish (OECD 210)

Measured toxicity data from GTL base oil demonstrate lack of chronic effects on fish. The No Observed Effect Loading Rate (33 d NOELR) was 100 mg/L loading rate WAF at this study.

 

Short-term toxicity to aquatic invertebrates (OECD 202)

The test results showed that GTL base oil was not acutely toxic to aquatic invertebrates at a loading rate of 100 mg/l; the ELR₅₀ (freshwater invertebrates) was >100 mg/l.

 

Long-term toxicity to aquatic invertebrates (OECD 211)

In the test with GTL base oil there were no adverse effects at the highest loading rate (100 mg/l); the long-term NOELR for freshwater invertebrates was ≥100 mg/l.

 

Toxicity to algae and cyanobacteria (OECD 201)

The test results showed that GTL base oil was not acutely toxic to aquatic algae at a loading rate of 100 mg/l; the ELR₅₀ (algae) was >100 mg/l and the NOELR was ≥100 mg/l.

 

Toxicity to microorganisms (OECD 209)

GTL base oil was found to be not toxic for aquatic microorganisms at a loading rate of 1000 mg/l; the 3h-LC₅₀ was > 1000 mg/l and the 3h-NOEC: ≥1000 mg/l.

 

Based on these data, it can be concluded that the toxicity of the registration substance 'Paraffin waxes (Fischer-Tropsch), isomerization' to aquatic organisms can also be expected to be non-toxic to aquatic organisms and with no effects at the water solubility limit (saturation).

Supporting studies for some endpoints are also available for the closely related Gas-to-liquids (GTL) substance 'Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics' (EC/List no. 940-734-7), which add further evidence for the lack of toxicity of hydrocarbons in the relevant carbon range to aquatic organisms.