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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Reliable data on the bioconcentration potential of AOH are available for two of its constituents (phenanthrene and pyrene). Normalised to a fish lipid content of 5%, the highest BCF was determined to be ca. 1150. This value is taken to describe the bioaccumulation potential of AOH.

Key value for chemical safety assessment

BCF (aquatic species):
1 150 L/kg ww

Additional information

Due to the complex composition ofthe substance distillates (coal tar), heavy oils (anthracene oil >50 ppm BaP, AOH [CAS no. 90640-86-1]),a single BCF value cannot be determined for the substance. Relevant components (all PAH) will have their individual BCF values. Main constituents of AOH are among others phenanthrene and pyrene (see Chapter 1.2). These substances will be used as marker substances for the bioaccumulation potential of AOH. In combination and together with additional information, they are considered to characterise AOH as a whole as other PAH present in AOH will exhibit similar characteristics (see reference WHO, 2003).

BCF for phenanthrene and pyrene have been determined in a study similar to OECD TG 305 of high quality using a flow-through system (Jonsson et al., 2004). Reliability of 1 was assigned to this study according to EU (2008), Tab. 3.28, and by Lampi and Parkerton (2009). BCF were determined using steady state conditions and kinetic parameters (uptake rate constant k1 and depuration rate constant k2) at two different exposure levels. Original values for phenanthrene were 700 and 1623 (BCFSS) and 810 and 2229 (BCFK). BCF for pyrene were 50 and 53 (BCFSS) and 145 and 97 (BCFK), respectively.

Several facts can be noticed. BCFs of pyrene are much lower than BCF for phenanthrene although pyrene is the more lipophilic of both substances based on their log Pow. Reason is that uptake of pyrene is reduced while excretion is the same or even higher compared to phenanthrene. For both substances, BCFSS are lower than the kinetic BCF, and the effect of different exposure concentrations is much higher for phenanthrene compared to pyrene (but exposure levels of pyrene are only 1/10 of the exposure level of phenanthrene).

Overall, BCF are low to moderate. The only value being higher than 2000 is the BCFK for phenanthrene at the high exposure concentration.

To put this values in perspective it has to be noted that lipid content of the test species (sheepshead minnow, Cyprinodon variegatus) is high (approx. 10%). For highly lipophilic test substances (log Pow > 3) like PAH, BCF can be normalised to a lipid content of 5% in order to match results between different studies (compare to OECD TG 305, adopted Oct. 2012). This normalisation has been performed by Lampi and Parkerton (2009) in their expertise. Resulting BCF values for the high exposure level for phenanthrene are 837 (BCFSSL) and 1149 (BCFKL) being now far below the threshold value of 2000.

Based on combined information and evidence, it is estimated that other PAH present in AOH will behave in a similar way. Therefore, it is considered that the BCF of phenanthrene will adequately characterise the bioaccumulation potential of AOH.

The highest BCF value determined for phenanthrene and normalised to a 5% lipid content in fish (BCFKL= 1149) is used to characterise the bioaccumulation potential of AOH. Based on this data, the BCF of AOH is below 2000.

References:

Lampi M and Parkerton T (2009) Bioaccumulation Assessment of PAHs - Review Paper Prepared for CONCAWE, October 2009

EU (2008) Coal-Tar Pitch, high temperature - Risk Assessment. European Union Risk Assessment Report, The Netherlands

Jonsson G, Bechmann RK, Bamber SD, Baussant T (2004) Bioconcentration, biotransformation, and elimination of polycyclic aromatic hydrocarbons in sheepshead minnows (Cyprinodon variegatus) exposed to contaminated seawater. Environ. Toxicol. Chem., 23, 1538-1548