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

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.05 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.022 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

10 000 mg/L

Assessment factor:

1

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

4.2 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

1.83 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.052 mg/kg soil dw

Assessment factor:

50

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

1.38 mg/kg food

Assessment factor:

30

Additional information

Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht) is a UVCB substance and consists of a complex combination of highly condensed polycyclic aromatic hydrocarbons (PAH). Due to the production process (high temperature distillation), it is less volatile, and its matrix is more highly condensed than the precursor material pitch, coal tar, high-temp.[CAS No. 65996-93-2] (coal tar pitch).

The substance as such shows highly inert properties. The solid matrix is practically insoluble in water (significantly less than 0.2 mg carbon/L at a loading of 1000 mg substance/L). A more extensive characterisation is given in Chapter 7.1. Solubility in organic solvents is also limited (e.g. toluene ca. 50 %). Typical constituents that can be analysed (GC analysis) are higher polycyclic aromatic hydrocarbons containing fused 5- and 6-ring systems. In GC analysis only ≤ 1 % of the substances present can be identified. Concentrations of major constituents are in the range of 0.05 to 0.2 %. Typical benzo[a]pyrene concentration is approx. 0.04 % while total analysable EPA PAHs amount to ca. 0.4 %.

Under environmental conditions, there will be no or only a very low environmental availability of the substance CTPhtht itself or of its constituents. Therefore, the substance is not considered an environmentally hazardous substance due to its inert inherent properties: because of its poor water-solubility and its complex high-molecular aromatic structure, it can be neither biodegraded nor bioaccumulated. As compared with coal-tar pitch, the precursor substance [CAS no. 65996-93-2], bioavailability of polyaromatic components has been further reduced due to technical after-treatment.

Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht) failed to show acute aquatic toxicity. Using coal tar pitch (supporting substance, precursor material) as test material, daphnia and alga gave no evidence of chronic adverse effects up to a loading of 100 mg/L. It can be assumed that this holds for the target substance, too. Long-term studies in fish are not available. However, they are not supposed to generate chronic toxic effects that are relevant for classification. Furthermore, the classification proposal outlined above will include the aspect of chronic hazard.

Nevertheless, for precautionary reasons and as worst-case scenario, risk assessment will take PAH into account. In order to characterise a potential toxicity of CTPhtht towards the environment, benzo[a]pyrene (BaP) has been selected as marker substance. PAH present in CTPhtht show essentially similar environmental toxicities, and BaP is the best investigated of these 5- and 6-ring PAH. Therefore, PNECs are derived based on toxicity data of BaP.

PNECs are derived according to ECHA Guidance on information requirements and chemical safety assessment, Chapter R.10: Characterisation of dose [concentration]-response for environment (May 2008). Explanation/justification for each PNEC is given above.

Conclusion on classification

The water-accommodated fraction (WAF) approach is considered most appropriate to classify Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht) in accordance with the recommendations in the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures (OECD, 2000). The classification criteria relate to the loadings.

CTPhtht produced no acute aquatic toxicity under standard test conditions in fish (OECD TG 203), in daphnia (OECD TG 202), and in algae (OECD TG 201). The effective loadings, EL50/LL50 values, were consistently higher than 100 mg/L. Based on weight of evidence, there is no concern over PAH-induced acute phototoxicity for the target compound, CTPhtht. Furthermore, pitch has no bioaccumulation potential.

In accordance to Regulation (EC) No 1272/2008, there is no need to classify pitch for acute toxicity. It is recommendable to classify the pitch material for long-term aspects as a potential source of environmental release of PAHs, which may be a cause of concern. This precautionary principle is covered by the “safety net” classification (Category: Chronic 4) [CLP Directive 1272/2008, 2nd ATP: EU Regul. 286/2011, 4.1.2.6, Table 4.1.0], hence H413 Chronic 4 is proposed.