Hydrocarbons, C13-C20, n-alkanes, isoalkanes, cyclic, aromatics (40-60%)

Ecotoxicological Summary

Additional information

The ecotoxicity of hydrocarbons, C13-C20, n-alkanes, isoalkanes, cyclics, 40 -60% aromatics has been examined in a series of studies on fish, Daphnia and algae. Studies have been conducted with C13-C20, n-alkanes, isoalkanes, cyclics, 40 -60% aromatics or with read-across substances.

The most conservative results of aquatic studies showed this substance to be of low toxicity, with LL50 or EL50 values of >3240 mg/L (Acartia), >1000 mg/L (fish), and 51 mg/L (algae). All of these studies were conducted in Water Accomodated Fraction (WAF) studies because of the limited water solubility. A test on microorganisms resulted in no toxicity up to 1000 mg/L. One study is available on chronic aquatic toxicity to fish with a NOELR of 5000 mg/L. For Daphnia a chronic values was determined to 17 mg/l (NOELR).Standard tests for terrestrial endpoints are intended for single substances and are not appropriate for the risk assessment of this complex substance. For the purpose of risk assessment, soil PNECs for hydrocarbon blocks have been derived using aquatic PNECs and the equilibrium partitioning method (EqP) using representative structures. Studies on long-term or reproductive toxicity to birds do not need to be conducted due to the existence of a large mammalian dataset demonstrating low toxicity to higher organisms.

Conclusion on classification

Due to the range of carbon atoms between 13 to 20, tests on biodegradation with different streams within this substance result in different rates of degradation. Due to the chemical nature of hydrocarbon UVCB cuts with a higher long-chain content will degrade to a lesser extent within the limits set for ready biodegradation according to OECD 301 guideline than cuts with lower long-chain content. Tests conducted with different streams of hydrocarbons, C13 -C20, n-alkanes, isoalkanes, cyclics, 40-60% aromatics support that this substance is quickly biodegraded and to large extents. However, available data range along cut-off criteria for ready biodegradation, with some streams fulfilling strict ready biodegradation criteria and others close to, failing the 10-day window or only slightly below 60% degradation. Products from hydrocarbons, C13 -C20, n-alkanes, isoalkanes, cyclics, 40 -60% aromatics might differ in the amount of different chain lengths present. To allow for different products, a split of classifcation is undertaken here, where products with a predominant chain length between C13 - C18 are not classified for the environment and products with a predominant chain length of C16 - C20 are classified chronic aquatic category 4 (GHS/CLP) and R53 (DSD). Besides not readily biodegradable this classification is based on the most sensitive available long-term data of below 1 mg/L for C16 - C20 hydrocarbons.