Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p9
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 9/14)
Character Range: 2707935–2715940

et al. (2010) suggests that deca‑BDE is taken up and translocated within the plants assessed (ryegrass, alfalfa, pumpkin, squash, maize and radish). Nineteen lower brominated (di‑ to nona‑) PBDEs were detected in the soil and plant samples and five hydroxylated congeners were detected in the plant samples, indicating debromination and hydroxylation of BDE‑209 in the soil−plant system. Evidence of a relatively higher proportion of penta‑ through to di‑BDE congeners in plant tissues than in the soil indicates that there is further debromination of PBDEs within plants or lower brominated PBDEs are more readily taken up by plants.

On the basis of the available information, the potential for the uptake of lower BDEs into home‑grown produce has been considered in the derivation of an HIL A. This has been undertaken on the basis of the equations presented in Appendix B with the following parameters and plant uptake factors estimated:
Parameter                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   Value              Reference/Comment
Parameters
Koc                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         1 698 000 (cm3/g)  Refer to note below*
log Kow                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     6.84               RAIS (2010) for penta‑BDE (BDE‑99)
Diffusivity in water                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        5.32x10‑6 (cm2/s)  Estimated as per Guan et al. (2009)
Calculated Plant Uptake Factors (mg/kg produce fresh weight per mg/kg soil)
Green vegetables                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            0.00026            calculated
Root vegetables                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             0.0038             calculated
Tuber vegetables                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            0.079              calculated
Tree fruit                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  0.00096            calculated
* The estimation of potential plant uptake of BDE is sensitive to the value of Koc adopted. The data would normally be derived from RAIS (2010) for consistency; however, the data provided is only for penta‑BDE with data from no other lower BDEs presented for comparison. Data presented in ATSDR (2001) suggests log Koc ranges from 2.895.1 for penta‑BDE and from 5.926.22 for octa‑BDE. Review by Guan et al. (2009) provides log Koc values for the lower BDEs (BDE‑28 to BDE‑208) that range from 5.736.49. Due to the range of values provided for the lower BDEs, the average of values presented by Guan et al. (2009), log Koc = 6.23, has been adopted.

2.3.5         Intakes from Other Sources – Background
Background intakes were evaluated by NICNAS (2007) on the basis of PBDE levels in blood rather than as an intake. The presence of PBDEs in blood lipids indicates exposure by the general population; however, the data does not determine the major source of exposure. Data available from FSANZ (2007) suggests that dietary sources are likely to be low, therefore house dust may be the major source, but there is little correlation between exposure levels and house construction/contents. FSANZ notes a review by USA where dietary exposures did not explain the current body burden and exposures to hose dust were estimated to account for 82% of the total intake. Based on information presented in the available reviews, the following can be noted with