Bioaccumulation of decabromodiphenyl ether (BDE209) in earthworms in the presence of lead (Pb)

• Pb addition can affect BDE209 bioaccumulation compared with exposure to BDE209 alone.
• High level of Pb exposure can facilitate the uptake of BDE209 through the skin.
• The elimination of BDE209 in earthworms augmented after 21 d in all the treatments.
• BDE209 can be debrominated to different products in earthworms in the presence of Pb.

BDE209 (decabromodiphenyl ether) and lead (Pb) are the main contaminants at e-waste recycling sites, and their potential toxicological effects on terrestrial organisms have received extensive attention. However, the impact on earthworms of exposure to the two chemicals remains almost unknown. Therefore, indoor incubation tests were performed on control and contaminated soil samples to determine the uptake and transformation of BDE209 in the presence of Pb for the first time. The results have demonstrated that Pb addition can affect BDE209 bioaccumulation efficiency compared with exposure to BDE209 alone. For a low BDE209 concentration (1 mg kg−1), Pb addition barely affected the uptake of BDE209, whereas for a high BDE209 concentration (100 mg kg−1), Pb addition elicited a complex response. Scanning electron microscope (SEM) observation indicated that a higher level of Pb (250 and 500 mg kg−1) facilitated the uptake of BDE209 through the skin. Gas chromatography/mass spectrometry (GC/MS) analysis showed that the peak of BDE209 accumulation usually appeared in the joint exposure groups involving 10 or 100 mg kg−1 BDE209 and 250 mg kg−1 Pb, and the average bioaccumulation factor (BAF) was 0.53, which is more than 1.2 times that of single exposure to BDE209 (average = 0.44). Also, the earthworms eliminated more BDE209 after 21 d, and the biodegradation products were mainly BDE206 and BDE208. Furthermore, Pb addition can affect the transformation efficiency of BDE209 in earthworms, and several lower bromodiphenyl ethers can be detected. The results of these observations have provided a basic understanding of the potential ecotoxicological effects of joint PBDE and heavy metal exposure on terrestrial invertebrates.