Uptake and transformation of decabromodiphenyl ether in different rice cultivars: Evidence from a carbon-14 study

Abstract

The differences of PBDE absorption, accumulation, and metabolism in different cultivars of the same crop are rarely explored. This study used ¹⁴C tracing to fully demonstrate the uptake and transformation of soil-borne BDE209 in three rice cultivars, including two indica (HHZ and YD1) and one japonica cultivars (NJ3). Results showed that about 6.9, 17.2, and 17.4% of the applied ¹⁴C-BDE209 were transformed to ¹⁴C-metabolites in soils planted with HHZ, YD1, and NJ3, respectively. The ¹⁴C-BDE209 and its ¹⁴C-metabolites in soil could be absorbed by the rice and gradually transported to its root, stem, leaf, and grain, with the total whole-plant uptake of 8.52, 4.55 and 3.43 nmol for HHZ, YD1, and NJ3, respectively. The cultivar of HHZ had the greatest whole-plant ¹⁴C absorption but the lowest ΣPBDEs residues in its grain, with the ΣPBDEs of 421.8, 454.2 and 967.0 ng g^-1 for HHZ, YD1, and NJ3, respectively. BDE-209 accounted for 90%, 31% and 50% of the ΣPBDEs in the grain from HHZ, YD1, and NJ3, respectively. The estimated daily intake (EDI) amounts of ΣPBDEs were 928, 1056, and 2675 ng kg^-1 bw d^-1 via consuming rice grains from HHZ, YD1, and NJ3, respectively, which were below the safe threshold limits for human consumption. This study proved the different BDE-209 absorption, accumulation and transformation in different rice cultivars, which potentially suggests the need of considering cultivar differences in assessing the dietary risks of PBDEs.

Keywords: Absorption; Bioaccumulation; Carbon-14 tracing; Decabromodiphenyl ether (BDE-209); Rice cultivars; Risk assessment.