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Studies on terrestrial toxicity with anthracene oil (benzo[a]pyrene < 50 ppm; AOL) itself could not be identified. But data obtained with phenanthrene as test substance are available. These will be used to characterise the terrestrial toxicity of AOL.

AOL contains mainly three-ring aromatic compounds and to a lesser extent PAHs with four rings (see Chapter 1.). Two-ring aromatics are minor. In combination, these substances will constitute the terrestrial toxicity of AOL.

Main constituent of AOL is phenanthrene. It is present in AOL in concentrations up to 31 % (average 28 %). The toxicity to soil organisms of phenanthrene is comparable to the terrestrial toxicity of other constituents of AOL. Even if individual constituents of AOL may have a somewhat higher toxicity to soil organisms, this is counterbalanced by the much higher concentration of phenanthrene. Therefore, the terrestrial toxicity of phenanthrene is considered to be representative for total AOL integrating the toxic effects of all its other PAH constituents. Thus, phenanthrene can be used as substitute and marker substance to characterise the terrestrial toxicity of total AOL.

Terrestrial toxicity of phenanthrene has extensively been evaluated in the EU Risk Assessment Report of pitch, coal tar, high-temp. (EU 2008). The toxicity of phenanthrene to soil organisms reported here is based on this evaluation.

Studies with phenanthrene as test material have been identified for soil macroorganisms except arthropods (annelida), for arthropods (collembola, crustacea), for terrestrial plants, and for microbial processes.

Soil macroorganisms except arthropods

Long-term (either 21 or 28 d) results are available from four studies performed with three different species (Eisenia fetida, Eisenia venata, and Enchytraeus crypticus). NOEC/EC10 values (normalised to a standard soil with 2 % organic carbon or 3.4 %/ organic matter, respectively) range from 5.8 mg/kg soil dw (Bowmer 1993) to 57 mg/kg soil dw (Droge et al. 2006/Bleeker et al. 2003) with three values between 31 and 57 mg/kg soil dw. The lowest value results from a 21 d reproduction study with Eisenia fetida (Bowmer 1993). The study with Eisenia venata (Sverdrup et al. 2002, EC10 = 31 mg/kg soil dw) is not presented in IUCLID.

Terrestrial arthropods

The effect of phenanthrene on terrestrial arthropods was investigated in long-term studies with collembolans (Folsomia fimetaria, Folsomia candida) and with crustaceans (Oniscus assellus, Porcellio scaber). Collembolans are subject of four studies. Endpoint of each study was reproduction. In the study with crustaceans, growth as parameter was reported. When effect levels are normalised to a standard medium (2 % organic carbon or 3.4 % matter organic matter), NOEC/EC10 values are close together ranging from approx. 12 to 29 mg/kg soil dw (Sverdrup et al. 2001/2002) with a NOEC of ≥ 27 mg/kg soil dw for the crustaceans (van Brummelen et al. 1996). The value 12 mg/kg soil dw was determined for F. fimetaria exposed to a phenanthrene spiked soil that was aged for 120 days prior to the exposure of the test animals. In this study, soil aging was investigated covering periods of 10, 40, and 120 days (EC10 values: 18, 18, and 12 mg/kg soil dw) (Sverdrup et al. 2002). The EC10 value for freshly spiked soil without aging was 29 mg/kg soil dw (Sverdrup et al. 2001). In order to account also for soil aging effects, the geometric mean of the four values (18 mg/kg soil dw) was calculated to represent toxic effects of phenanthrene to collembolans. This EC10 value is the lowest compared to results of terrestrial arthropods with non-aged soil.

Terrestrial plants

The toxicity of phenanthrene to terrestrial plants has been investigated in one study covering three plant species (Sverdrup et al. 2003). Effects were similar for two species (Sinapsis alba and Trifolium pratense). One plant was distinctly less sensitive (Lolium perenne). EC20 and EC50 values are reported. These were used to estimate EC10 values using a log-logistic dose-response relationship. Corrected to a standard soil with 2 % organic matter, EC10 values were 30, 33, and 218 mg/kg soil dw for T. pratense, S. alba, and L. perenne, respectively.

Soil microorganisms

In a study with phenanthrene as test substance and agricultural soil as substrate, nitrate formation was determined (exposure period 4 weeks). The EC10 (nitrate formation rate) was determined to be 42 mg/kg soil dw.

Birds

Regarding the toxicity of phenanthrene to birds, no data could be located.

Conclusion

Overall, long-term terrestrial toxicity data for phenanthrene are available for annelids, collembolans, crustaceans, terrestrial plants, and soil microbial processes (nitrate formation). Thus, data on at least three species covering three trophic levels are available.

The data obtained on the annelid Eisenia fetida (Bowmer 1993) provide the lowest NOEC/EC10 of all the species tested. This value (5.8 mg/kg soil dw) is used for the derivation of the PNEC soil.

Reference:

EU (2008): European Union Risk Assessment Report - Coal-Tar Pitch, high temperature. The Netherlands (rapporteur) (URL:https://echa.europa.eu/documents/10162/433ccfe1-f9a5-4420-9dae-bb316f898fe1)