Dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-furans) in traditional clay products used during pregnancy

► We determined PCDD/F levels of clays taken orally during pregnancy. ► PCDD/F levels in some clays were high, up to 103 ng TEQ kg−1. ► We compared congener patterns of clay and human milk samples from Africa. ► PCDD/F patterns in some breast milk suggest a relationship with clay consumption. ► Use of contaminated clay presents a health risk for the developing fetus.