Aromatic hydrocarbons, C9-12, benzene distn.

Ecotoxicological Summary

Additional information

The ecotoxicity of C9 aromatics have been examined in a series of studies on fish, Daphnia and algae, as well as in microorganisms and birds. The most conservative results of aquatic studies showed C9 aromatics to be of moderate toxicity, with LC50 or EC50 values of 9.2 mg/L (fish), 3.2 mg/L (Daphnia), and 2.9 and 2.6 mg/L (for growth and biomass, respectively, of algae). All of these studies were conducted in Water Accommodated Fraction (WAF) studies because of the limited water solubility and multi-constituent composition (UVCB) of C9 aromatic materials. A study conducted with microorganisms demonstrated no significant toxicity (EC50 >99 mg/L), indicating that there would not be inhibition or toxicity to sewage treatment plant microorganisms. Finally, both oral and dietary studies with bobwhite quail indicated no acute toxicity or mortality to birds from C9 aromatics (LD50/LC50 > 2250 and 6500 mg/kg, respectively). NOELs for these studies were 293 and 2340 mg/kg, respectively, due to reduced body weight (likely the result of palatability issues) in the former case and as appearance and behavioural sub-lethal effects in the latter case.

Conclusion on classification

Substance is a hydrocarbon UVCB: The hydrocarbon block method is used for environmental risk assessment (see REACH guidance, R7, app.13-1). Soil PNECs for hydrocarbon blocks have been derived using aquatic PNECs and the equilibrium partitioning method (EqP) using representative structures. The aquatic PNECs 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 Section 13. Given the large database of organisms included in the target lipid model, an assessment factor of one has been applied to the HC5.