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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Calculated BCF values for rosin esters range from 554.8 to 8053 L/kg for mono-esters and 3.82 to 137.2 L/kg for di-esters; the BCF for

tri-esters and tetra-esters is 3.162. Measured BCF values for resin acids range from <25 to 130.

Key value for chemical safety assessment

Additional information

Rosin ester substances are poorly soluble UVCBs and as such conducting a BCF study would be very complex. No measured bioaccumulation data is available for rosin ester substances. Measured Kow values are available for rosin ester substances, however results are variable due to the difficulties with testing these substances, with log Kow values ranging from 2.44 to > 6.5. Due to the difficulties with measuring Kow for these substances and the fact that a single measured Kow is unlikely to be representative of the constituents in the UVCB, bioaccumulation potential is assessed based on QSAR predictions for representative structures in the UVCB substances.

Rosin ester substances are UVCB substances containing rosin ester and non-esterified resin acid constituents. The bioaccumulation potential of the substances is therefore assessed based on a QSAR screening assessment of rosin ester constitiuents and measured data for resin acids.

Bioconcentration/bioaccumulation was estimated for representative structures of mono, di, tri and tetra ester substances using the US EPA's EPISuite model BCF BAF (regression-based method). Calculated BCF values for rosin ester constituents range from 554.8 to 8053 L/kg for mono-esters and 3.82 to 137.2 L/kg for di-esters; the BCF for tri-esters and tetra-esters is 3.162. Calculated BAF values for rosin substances range from 131.2833 to 2319.69 L/kg for mono-esters, 21.8399 to 1450.283 L/kg for di-esters and 0.893 to 0.9041 L/kg for tri-esters; the BAF for tetra-esters is 0.893.

The applicability domain of the BCFBAF model is based on the molecular weight and log Kow of 527 training set compounds (minimum MW: 68.08, maximum MW: 959.17, average MW: 244, minimum log Kow: 1.37, maximum log Kow: 11.26). According to the training set molecular weight range and log Kow range, di-, tri- and tetra-esters are outside of the BCF model domain.

Although some of these constituents are outside the domain of the QSAR model, the QSAR approach is considered to be appropriate as a screening assessment in order to identify any constituents that may require further assessment. Measured BCF values are available for resin acid constituents (Niimi and Lee 1992). Rainbow trout (Oncorhynchus mykiss) were exposed to nine resin acids that included abietic, dehydroabietic, chlorodehydroabietic, dichlorodehydroabietic, neoabietic, pimaric, isopimarie, sandaracopimaric, and palustric acids for 20 days, followed by a 10 day depuration period. BCF values for resin acids were determined to range from <25 to 130.