Hydrocarbons, C13-16

Endpoint summary

Additional information

C14-20 Aliphatics (≤2% aromatic) are poorly soluble in water and made of constituents with various water solubilities. As a consequence, most studies are performed with "Water Accomodated Fractions" (WAFs) and the results must be expressed as "loading rates" instead of "concentrations".

Short-term toxicity to fish

The fish were exposed to water accomodated fractions (WAFs) and the results expressed as loading rates. The reported LL₅₀values for C14-20 Aliphatics (≤2% aromatic) range from 0 >1028 mg/L to >70 g/L. No LC₅₀could be derived from acute short-term studies as they were only based on loading. The risk assessment was performed using the Petrorisk model.

Long-term toxicity to fish

Petrotox calculations determined that for all substances from C14-20 Aliphatics (≤2% aromatic) were not toxic to fish. Results of computer modelling to estimate chronicity in 28 -day freshwater fish study, based on growth, show that Hydrocarbons, C14 -C20, aliphatics (≤2% aromatics) will not produce toxicity at or below its maximum attainable water solubility.

Short-term toxicity to aquatic invertebrates

C14-20 Aliphatics (≤2% aromatic) are poorly soluble and made of constituents with various water solubility. As a consequence, the exposures were performed with Water Accommodated Fractions (WAFs). Therefore, the results are based on nominal loadings and the LC₅₀ value given below is actually a LL₅₀ (lethal loading) value. No LC₅₀ could be derived from the acute toxicity studies.

The water accommodated fraction (WAF) of Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, <2% aromatics did not produce a 50% effect (mortality) with Chaetogammarus marinus at a loading of 10,000 mg/L after a 96-hour exposure. Therefore, the 96-hour LL₅₀ is reported as >10,000 mg/L. There was no mortality at the 10,000 mg/L loading level after 96 hours. Therefore, the 96-hour NOELR for mortality is reported as 10,000 mg/L. There was also no mortality in the control.

The water accommodated fraction (WAF) of Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, <2% aromatics did not produce a 50% effect (immobility) with Daphnia magna at a loading of 1000 mg/L after a 48-hour exposure. Therefore, the 48-hour LL₅₀ is reported as >1000 mg/L. There was no mortality at the 1000 mg/L loading level after 48 hours. Therefore, the 48-hour LL0 for mortality is reported as 1000 mg/L. There was also no mortality in the control.

 

Many study reports that investigated the toxicity of the substance Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, ≤2% aromatics on a marine copepod, Acartia tonsa exposed to water accommodated fractions (WAFs) are available. Several studies indicate very high values (up to 69155 mg in Altin, 1998b), In most of the studies the calculation of LL₅₀ could not be achieved because of the low mortality levels obtained (Aunaas, 1996a and c; Larsen, 2006a, b, d and e; 2008a-c). When more than 5 values are available for LL₅₀, the geometric mean of all the values is considered for LL₅₀. However, in this particular case, as a great number of studies could not achieve the calculation of LL₅₀, the geometric mean cannot be calculated, but 9 studies among 11 found that LL₅₀ was greater than 3000 mg/L. Therefore, it is considered that LL₅₀ is >3000 mg/L.

Long-term toxicity to aquatic invertebrates

The aquatic toxicity of was estimated using the Petrotox computer model, which combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components as a function of substance loading with the Target Lipid Model used to calculate acute and chronic toxicity of non-polar narcotic chemicals. Petrotox computes toxicity based on the summation of the aqueous-phase concentrations of hydrocarbon block(s) that represent a hydrocarbon substance and membrane-water partitioning coefficients (K_MW) that describe the partitioning of the hydrocarbons between the water and organism.

The 21-d NOELR for aquatic invertebrates, Daphnia magna and Ceriodaphnia dubia, based on reproduction was found to be >100 mg/L and >1000 mg/L, respectively according to Petrotox calculations. The experimental studies could not determine LL₅₀.

Toxicity to algae and cyanobacteria

Fourteen study reports were available for this end-point, all dealing with the toxicity of the substance Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, < 2% aromatics on algae growth rate. All the studies used the marine species Skeletonema costatum. None of the studies allowed calculating 48h-EL₅₀ that was never reached. All LL₅₀ are superior to 10000 mg/L based on WAF studies.

Growth of an alga culture,Pseudokirchnerella subcapitata, as measured by biomass and growth rate, exposed to a 1000 mg/L water accommodated fraction of Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, <2% aromatics was not inhibited when compared to the control after a 72-hour exposure. Therefore, the 72-hr EL⁵⁰ and NOELR values for these two endpoints are reported as >1000 mg/L and 1000 mg/L, respectively.

Toxicity to microorganisms

Hydrocarbons, C14-C20, aliphatics, ≤2% aromatics were not found to be toxic for aquatic microorganisms (LC₅₀ >100 mg/L).