T.R. Chowdhury et al; reply from J.M. McArthur Nature 401, 545–547 ( 1999) The form of citation of one of the references given in this exchange (ref. 10 of Chowdhury et al., ref. 6 of McArthur) was misleading and should have been written as “British Geological Survey/Mott MacDonald Ltd Groundwater Studies for Arsenic Contamination in Bangladesh (1999).” This is because it is the final report of Phase 1: Rapid Investigation Phase, not of the overall project, for which the final report will appear in 2000.