2-(phenylmethoxy)naphthalene

Toxicity to soil macroorganisms except arthropods

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil macroorganisms:

1 000 mg/kg soil dw

Additional information

SNIF (Structure Notification Interchange Format) data provided by ECHA are available for the hazard assessment of the test substance. In an acute earthworm study according to OECD 207 the NOEC in Eisenia fetida was determined to be 1000 mg/kg dry weight (SNIF NOTOX 1990).

Due to the test substances high adsorption potential (log Koc = 4.57, calculated value, SRC KOCWIN v.2.00, 2011) the substance is expected to adsorb to the solid soil phase. Additionally, the test substance is highly insoluble in water and has to be regarded as very persistent in the environment. Furthermore, the acute aquatic toxicity assessment covering all trophic levels and a long term study on daphnids reveal that the test substance is not harmful in the range of water solubility. For test substances holding properties like these, the ECHA Guidance on information requirements and chemical safety assessments, Chapter R.7c suggests:

1. […] it will normally not be possible to derive a robust PNEC for the purposes of a soil screening assessment from acute aquatic toxicity testing showing no effect. This is, particularly true for poorly soluble substances. Where the water solubility is <1 mg/l, the absence of acute toxicity can be discounted as reliable indicator for potential effects on soil organism due to the low exposures in the test.The absence of chronic or long-term effects in aquatic organisms up to the substance solubility limit, or of acute effects within the solubility range above 10 mg/l can be used as part of a Weight of Evidence argument to modify/waive the data requirements of Annex IX and X (page 121).

2. In general, the data required should cover not just different taxa but also different pathways of exposure (e.g. feeding, surface contact), and this should be taken into account when deciding on the adequacy and relevance of the data. Thus earthworm testing allows potential uptake via each of surface contact, soil particle ingestion and porewater, while plant exposure will be largely via porewater (page 121 and 122).

3. In general, where there is […] no effects in chronic toxicity at the limit of water solubility, […] a single short-term soil test on a suitable species would be adequate to meet the requirements of Annex IX (page 122).

4. Where the substance is highly adsorptive, e.g. where the log Kow/Koc >5, and/or the substance is very persistent in soil, this single test should be a long-term test. Substances with a half-life >180 days are considered to be very persistent in soil. This persistence would be assumed in the absence of specific soil data, unless the substance is readily degradable. The choice of test (invertebrate / plant / micro-organism) would be based on all the information available, but in the absence of a clear indication of selective toxicity, an invertebrate (earthworm or collembolan) test is preferred (page 122).

Based on these suggestions laid down in the ECHA Guidance on information requirements and chemical safety assessments, Chapter R.7c the registrant will conduct a long-term study on the reproduction of the earthworm Eisenia fetida (OECD 222) in 2012. Due to earthworms feeding behavior to ingest soil particles, it is assumed that, if there are any toxic effects of the test substance on terrestrial organisms at all, earthworms will be affected the most. Therefore, terrestrial studies on arthropods, plants and soil microorganisms will not be conducted unless effects will be ascertained in the proposed OECD 222 study.