Organic halogenated contaminants in mother-fetus pairs of harbor seals (Phoca vitulina richardii) from Alaska, 2000-2002

► Significant amounts of organic halogenated contaminants (OHs) were transferred from maternal harbor seals to their fetuses. ► HCH, HCB, PCNs, PBDEs and low chlorinated PCBs were preferentially transferred from mothers to fetuses. ► p,p′-DDE and highly chlorinated PCBs were retained in the mother to a greater extent. ► The retention of toxic congeners in the mother seals could threaten future reproductive success. ► Prenatal transfer of OHs could pose a threat to the critical early development of the fetuses.