2-(4-methyl-3-pentenyl)anthraquinone

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Summary:

Screening-level data indicate the potential for persistence of Catalyst 21513, based on lack of demonstrated biodegradability in ready biodegradability and enhanced biodegradability assays. Based on the screening data, the substance is considered to be “P”, and “potentially vP”.

Screening-level data indicate the potential for bioaccumulation exhibited by Catalyst 21513, based on an experimentally-determined log Kow of 5.3, which exceeds the screening criterion (log Kow ≤ 4.5) for both “not B” and “not vB”.

However, BCF values determined experimentally with three structure analogues show values well below the screening criteria. These values show a good agreement between the measured data and the predictability of the modelled values. Therefore the modelled BCF value for Catalyst 21513 can be considered reliable. On this basis the substance is considered as “not B”.

Screening-level data indicate that Catalyst 21513 is not toxic. The determinations that Catalyst 21513 is “not CMR” and “not T, R48” or “Xn, R48” are definitive determinations of “not T” with respect to human health endpoints. The short-term screening-level data for aquatic toxicity indicate that the substance is “not T.

In summary, the combined data indicate that Catalyst 21513 is not a PBT (P, not B, not T).

Persistence:

Screening-level data indicate the potential for persistence of Catalyst 21513, based on lack of demonstrated biodegradability in ready biodegradability and enhanced biodegradability assays.

Experimental data from two separate tests (ready biodegradability and enhanced ready biodegradability) indicate the likelihood that Catalyst 21513 is persistent in the environment.

The key study was an enhanced biodegradability assay of Catalyst 21513 by OECD Guideline 301F (manometricrespirometry test) for 60 days. No biodegradation of the test substance was found after 28 days (mean -5% ThODNH4); the 10-day window criterion was not passed. Therefore, Catalyst 21513 is considered to be not readily biodegradable. Additionally, after 58 days of incubation also no enhanced biodegradation was found. Thus, the substance is considered to be “P”and potentially”vP”).

Bioaccumulation:

Screening-level data indicate the potential for bioaccumulation exhibited by Catalyst 21513, based on an experimentally-determined log Kow of 5.3, which exceeds the screening criterion(log Kow≤ 4.5) for both “not B” and “not vB”

A determination regarding the classification of a substance with respect to bioaccumulation relies upon screening criteria and additional considerations, providing a weight-of-evidence demonstration based on BCF values predicted by QSAR modeling, and BCF measurements from three analogue substances. The QSAR model BCFWIN (a module contained within the United States Environmental Protection Agency software EPI-Suite) provides estimates of BCF based on the octanol-water partitioning coefficient (Kow). BCFWIN predicted that the BCF for Catalyst 21513 was 348 (based on a user-entered, experimentally-determined log Kow value of 5.3), or 1,679 (based on a log Kow value of 6.19 as predicted by KOWWIN in the EPI-Suite software). Both of these predicted BCFs are well below the threshold criterion for vB (BCF > 5000). Both of these predicted BCFs are also below the threshold criterion for B (BCF > 2000).

Experimentally-determined BCF values are available for three structural analogues of Catalyst 21513: a mixture of the structure analogues composed mainly of structure analogue no. 1 and structure analogue no. 2; as well as a mixture of the structure analogue composed mainly of structure analogue no. 1. In addition, QSAR predictions for the BCF of each structural analogue, based on the BCFBAF module within USEPA’s EPI-Suite v4.10, have been determined. The directly measured and modeled BCF values for each of these three structural analogues are discussed below.

The measured BCF values for the mixture of the structure analogues composed mainly of structure analogue no. 1 were determined at two concentrations: a BCF of 7.8 to 12.4 was reported at a concentration of 0.135 mg/L; and a BCF of 5.6 to 13.5 was reported at 0.0135 mg/L. Each of these measured BCF values was substantially below the threshold criteria for both B (BCF > 2000) and vB (BCF > 5000). The QSAR predictions for the BCF of structure analogue no. 1 (based on the BCFBAF module within USEPA’s EPI-Suite v4.10) were BCF = 92.31 L/kg w.w. (regression-based method), and BCF = 170.7 (Arnot-Gobas method, upper trophic). Both of these modeled BCF values were substantially below the threshold criteria for both B (BCF > 2000) and vB (BCF > 5000). A comparison of the measured and modeled values for the BCF of structure analogue no. 1 indicates that the modelled values are conservative estimates of BCF (i.e., biased toward overestimation of the BCF), approximately within an order of magnitude of the measured values.

The measured BCF values for structure analogue no. 2 were determined at two concentrations: a BCF of 250 to 360 was reported at a concentration of 2 ug/L; and a BCF of 11 to 250 was reported at 0.2 ug/L. Each of these measured BCF values was below the threshold criterion for B (BCF > 2000) and substantially below the threshold criterion for vB (BCF > 5000). The QSAR predictions for the BCF of structure analogue no. 2 (based on the BCFBAF module within USEPA’s EPI-Suite v4.10) were BCF = 353.5 L/kg w.w. (regression-based method), and BCF = 599.8 (Arnot-Gobas method, upper trophic). Both of these measured BCF values were below the threshold criterion for B (BCF > 2000) and substantially below the threshold criterion for vB (BCF > 5000). A comparison of the measured and modelled values for the BCF of structure analogue no. 2 indicates that the modelled values are conservative estimates of BCF and are in general concordance with the measured values.

The measured BCF values for the mixture of the structure analogues composed mainly of structure analogue no. 1 were determined at two concentrations: a BCF of 300 to 2100 (with a geometric mean of 776.25) was reported at a concentration of 0.135 mg/L; a BCF of 557 to 1070 was reported at 0.0135 mg/L. Each of these measured BCF values was below the threshold criterion for vB (BCF > 5000). However, there is some uncertainty with respect to the measured BCF values and the threshold criterion for B (BCF > 2000); the higher value from the BCF study at 0.135 mg/L exceeded the criterion. The QSAR predictions for the BCF of structure analogue no. 1 (based on the BCFBAF module within USEPA’s EPI-Suite v4.10) were BCF = 882.6 L/kg w.w. (regression-based method), and BCF = 573 (Arnot-Gobas method, upper trophic). Both of these modeled BCF values were below the threshold criteria for both B (BCF > 2000) and vB (BCF > 5000). A comparison of the measured and modelled values for the BCF of structure analogue no. 1 indicates that the modelled values are plausible estimates of BCF, within the range of the measured values.

The comparison of the measured values and modelled estimates of BCF in three structural analogues of Catalyst 21513 shows that the modelled values are in general concordance with measured values, providing conservative estimates of BCF (i.e., biased toward overestimation of the BCF ) for two of the three analogues. Therefore, it is unlikely that the QSAR model (the BCFBAF module within USEPA’s EPI-Suite v4.10) underestimates the potential for bioaccumulation in the aquatic environment.

The BCF values determined with the structure analogues show that there is a good agreement in the predictability of the measured and the modelled values. Thus the modelled BCF value for the Catalyst can be considered reliable.

Therefore, based on the screening criteria and other considerations, Catalyst 21513 is determined to be not “B”and notvB”.

Toxicity:

Screening-level data indicate that Catalyst 21513 is not toxic. The determinations that Catalyst 21513 is “not CMR” and “not T, R48” or “Xn, R48” are definitive determinations of “not T” with respect to human health endpoints. The short-term screening-level data for aquatic toxicity indicate that the substance is “not T”.

Likely routes of exposure:

The substance is manufactured in short campaigns using an automated batch, closed system. The crude sump melt is pumped into a heated, insulated ISO container.

The product is thus shipped to a Toll provided for pastillattion. The resulting pastilles are returned to origin for end use as catalyst. The substance is fully consumed in the final process.

There are no outputs to wastewater during manufacture and pastillation. In the final use, the catalyst is entirely consumed and protected by STP. Thus exposure of air and soil are considered unlikely, and thus there is a negligible chance of environmental exposure.