Coastal paddies could emerge as hotspots of arsenic accumulation in rice: A perspective from the Red River Delta

•Geographical disparity of As in rice in the Red River delta (RRD) was investigated.•The As content of RRD rice grain varied from 53 to 631 μg kg−1•Coastal area appears as a hotspot where As was rich in both rice grain and soil.•The observation of rice As in the RRD might reflect the tendency in other deltas.