[1] US FDA, Ctr Biol Evaluat & Res, Silver Spring, MD USA
[2] NCI, Bethesda, MD 20892 USA
[3] Noguchi Mem Inst, Accra, Ghana
[4] Univ Ghana, Dept Child Hlth, Accra, Ghana
[5] Lab Stamboulian, Buenos Aires, DF, Argentina
[6] St Marcelina Hosp, Dept Pediat Oncol, Sao Paulo, Brazil
[7] NCI, Div Canc Epidemiol & Genet, NIH, Rockville, MD 20892 USA