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Ecotoxicological information

Toxicity to soil macroorganisms except arthropods

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Description of key information

There are two earthworm reproduction studies available one for p-xylene and one for mixed xylenes (CAS 1330 -20 -7; substance composition equivalent to reaction mass of ethylbenzene and mixed xylenes). The study on p-xylene reports a NOEC of 71.1 mg/kg soil dry weight and an EC50 of 88.8 mg/kg soil dry weight (intial measured concentrations) based on mortality and effect on reproduction. The study on mixed xylenes (CAS 1330 -20 -7; substance composition equivalent to reaction mass of ethylbenzene and mixed xylenes) reported a NOEC of 42.6 mg/kg soil dry weight and an EC50 of 93.2 mg/kg soil dry weight (initial measured concentrations) based on effects on reproduction.

Due to the technical challenges of testing volatile substances, a TLM-EqP modeling framework was used to support terrestrial effect values derived experimentally and are presented as supporting studies. These data were considered reliable and comparable to experimentally derived values; however, were not used in the PNEC derivation in order to comply with ECHA FDL (2014) on using experimental data to derive PNEC. The hazard to soil organisms was assessed by using the experimental data.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:
88.8 mg/kg soil dw
Long-term EC10, LC10 or NOEC for soil macroorganisms:
42.6 mg/kg soil dw

Additional information

Due to the technical challenges of testing volatile substances, a TLM-EqP modeling framework was used to support terrestrial effect values derived experimentally and are presented as supporting studies. The estimated 28 day LL50 values from TLM QSAR were 22.082 - 74.410 mg/kg dw and 56 day long-term effects NOELR values from TLM QSAR were 4.2 30 - 14.255 mg/kg dw.

The Draft Screening Assessment Report (Environment Canada 2014) reports a 14 day NOEC for earthworms of 16 mg/kg dw from ESG International (2002).