Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons

Endpoint summary

Description of key information

Under environmental conditions, there will be no or only a very low environmental availability of the substance Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht) or its constituents. CTPhtht does not show acute aquatic toxicity and is supposed to generate no chronic toxic effects that are relevant for classification. However, for precautionary reasons, environmental risk assessment will take PAHs into account with benzo[a]pyrene (BaP) as marker substance, although the results of BaP describe worst-case conditions rather than being representative of CTPhtht itself.

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Additional information

Effects on aquatic organisms will be presented below for the registration substance CTPhtht, for the supporting substance, Pitch, coal tar, high temp. [CAS no. 65996-93-2], and for the marker substance benzo[a]pyrene.

Acute aquatic toxicity

Due to the poor solubility of CTPhtht in water, this material does not produce noticeable acute aquatic toxicity under standard test conditions in daphnia (OECD TG 202; Aniol et al. 2007a) and in algae (OECD TG 201, Aniol et al. 2007b). The EL50/LL50 values were consistently higher than 100 mg/L (loading).

Pitch, coal tar, high temp. [CAS no. 65996-93-2] as supporting substance exhibited no inhibitory effects on microbial growth and activity. In a cell proliferation test with Pseudomonas putida (Hillmann 1991) and in abioluminescence assay with photobacteria (Weck 1996), the EL0 was 10,000 mg/L.

Chronic aquatic toxicity (CTPhtht and structure-related Pitch, coal tar, high temp. [CAS no. 65996-93-2])

Daphnia: No data is available for CTPhtht itself. However, in a 21d reproduction study in daphnia (semi-static, OECD TG 211, NOACK et al. 2009), no adverse effects were observed in the presence of a water-extract from 100 mg/L powdered coal tar pitch, the structure-analogous compound. The NOEC was greater than 100 mg/L (nominal), which corresponded to a mean water-soluble fraction of 1.3 – 1.4 µg/L of 18 aromatic key compounds (16 EPA PAH plus 2). This underlines the extremely low bioavailability of this kind of compounds.

Alga: In an alga test (OECD TG 201, Aniol et al 2007b), the no-effect loading rate (NOELR) was 100 mg/L (limit concentration). There was no inhibition of the average specific growth rate by CTPhtht at the limit test loading rate of 100 mg/L at any observation time.

Fish: Long-term studies in fish are not available. However, CTPhtht is not supposed to generate chronic toxic effects that are relevant for classification taking into account test results for daphnia and alga.

Chronic aquatic toxicity (marker substance benzo[a]pyrene)

Daphnia: Long-term toxicity of BaP to daphnia was examined in a test according to the French guideline series AFNOR using Ceriodaphnia dubia (Bisson et al. 2000). EC10 (7d) was determined to 0.507 µg/L (meas.).

Alga: In a test with alga similar to EU method C.3 using BaP as test substance, an EC10 (72 h) of 0.78 µg/L (meas.) was determined (Bisson et al. 2000).

Fish: Long-term toxicity of BaP to fish was examined in an ELS study similar to OECD TG 210. A NOEC (42 d) of 4 µg/L (meas.) was determined.

Marine species: Long-term toxicity of BaP was determined in two marine species (molluscs and echinoderms). EC10 (48h) for the embryonic development of the salt water oyster Crassostrea gigas under UV-radiation was 0.5 µg/L (meas.) (Lyons et al. 2002). NOEC for developmental toxicity (gastrulation) of the purple sea urchin Strongylocentrotus purpuratus was also 0.5 µg/L (nominal) (Hose et al. 1985).