The interaction of lead exposure and pregnancy

The toxic effects of low-level lead exposure have been the subject of a good deal of research and media attention in recent times. In most countries, the acceptable occupational exposure limit for lead is being progressively decreased as the adverse health effects of lead are being identified at levels approaching those found in non-occupational environments. Due to the sensitive nature of the fetus to hazardous substances, the exposure to lead of the unborn child via maternal sources is of critical concern. Preterm delivery, congenital abnormalities and decreases in growth stature have all been associated with prenatal lead exposure at "acceptable" levels. There is an accumulation of evidence which indicates that maternal exposures prior to conception can play an important role in determining blood lead levels during pregnancy. In light of these observations the practice of removing the pregnant woman from lead sources may be of questionable value with regards to providing sufficient protection for the fetus. This article reviews the relevant literature pertaining to the mobilization of lead from bone during pregnancy and the toxicity of low-level lead exposure to the fetus, and briefly discusses some factors which may affect this toxicity.