Hydrocarbons, C5, n-alkanes, isoalkanes

Short-term toxicity to aquatic invertebrates

Description of key information

The estimated freshwater invertebrate 48 hour EL50 value is 53.18 mg/l based on mortality 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

53.18 mg/L

Additional information

The aquatic toxicity 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 calculated EL50 for the substance is 53.18 mg/l (48h). This is supported by the experimental study, Adema et al. 1987, for 2-methylbutane which reported a measured EC50 of 2.3 mg/l.

 

This result would not indicate that the pentanes would meet the criteria for toxic in the PBT assessment. However, the 48 hour EC50 of 2.3 mg/l would result in a classification of acute category 2 with the hazard phrase 'toxic to aquatic life'.

The hydrocarbon block method has been used for environmental risk assessment (see REACH guidance, R7, app.13-1). Aquatic PNECs for hydrocarbon blocks have been derived using the HC5 statistical extrapolation method and the target lipid model using representative structures. See Product Library tab in PETRORISK spreadsheet attached to IUCLID Section 13. Given the large database of freshwater organisms included in the target lipid model, an assessment factor of one has been applied to the HC5.