Environmental poisons can be dangerous to a pregnant woman. Environmental poisons and pollutants that can harm a developing fetus include lead, mercury, PCBs and pesticides.
Lead exposure increases the chance of miscarriage. Lead is readily transported across the placenta to the baby. Poisoning occurs as early as the 12th week of pregnancy.
Mercury exposure has been linked to cerebral palsy and microcephaly. Exposure usually occurs from contaminated fish. Grain contamination by mercury has also been reported.
PCBs (polychlorinated biphenyls) are not single compounds but mixtures of several compounds. Most fish, birds and humans have small, measurable amounts of PCBs in their tissues. PCBs have been blamed for miscarriage and fetal-growth retardation. We are exposed to PCBs through some foods we eat, especially fish.
Pesticides have been held responsible for an increase in miscarriage and fetal-growth retardation. Pesticides include a large number of agents used to control unwanted plants and animals. Human exposure is common because of the extensive use of pesticides. Those of most concern include DDT, chiordane, heptachlor and lindane.
The safest course is to avoid exposure, whether through the foods you eat or the air you breathe. Thoroughly wash all fruits and vegetables before eating. It may not be possible to eliminate all contact. If you know you will be around certain chemicals, wash your hands thoroughly after every exposure.