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Description of key information

The substance is an extremely complex hydrocarbon UVCB. The substance is comprised of 21 different categories of components. The total number of individual components is estimated to be nearly 1000. It has been estimated that there are 210 possible isomers in the category of dialkyl benzenes alone. Standard tests for this endpoint are intended for single substances and are not appropriate for the risk assessment of this complex substance. Further complicating the sediment testing of Benzene, mono-C10-13-alkyl derivs., distn. residues is the extremely low water solubility (WATERNT estimates from 2.61e-03 to 5.83e-07 mg/L), extremely high log Kow’s (KOWWIN estimates from 7.87 to 19.62) and extremely high log Koc’s (KOCWIN estimates from 5.21 to 11.30 L/kg) of the individual components. These properties indicate that the Benzene, mono-C10-13-alkyl derivs., distn. residues components will be tightly bound to organic material in soil and sediments and will have little, if any, bioavailability.

Three terrestrial toxicity studies have been conducted on Benzene, mono-C10-13-alkyl derivs., distn. residues. In an OECD 222 earthworm reproduction study, concentrations of Benzene, mono-C10-13-alkyl derivs., distn. residues of up to 1000 mg/kg (dry soil) had no effect on any of the measured endpoints (adult mortality, adult body weight, juvenile production). This resulted in NOECs of 1000 mg/kg (dry soil).

In an OECD 208 plant toxicity test, 10 plants species, representing both monocots and dicots, were exposed to Benzene, mono-C10-13-alkyl derivs., distn. residues for 21 days. For all species tested, the EC50 values were above the highest concentration tested while the NOECs ranged from 37 to 1000 mg/kg (dry soil) based on endpoints of emergence and growth.

An OECD 216 toxicity to microorganisms test was also conducted. Benzene, mono-C10-13-alkyl derivs., distn. residues was added to soil, and the nitrate formation measured after 28 days.The amount of nitrate formation was inhibited -3.21% in the test replicates as compared to controls. The EC50 based on inhibition of nitrate formation was >1000 mg/kg dry soil.  The NOEC was >= 1000 mg/kg dry soil.

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