LEAD AS A DEVELOPMENTAL TOXICANT: A REVIEW

A toxic substance is one which can produce its adverse effects in biological systems by interfering with their structure and function, which may lead to mortality. From the biological point of view, it can be consider that no chemical is either completely safe or harmful .The safe or harmful nature of toxic substance depends on the doses, duration and the time when animal is exposed to the particular toxic substance. Susceptibility to toxicant often depends on developmental stage. There are critical period of development during pre and postnatal time and a particular structure or function will be most sensitive to disturbance during its critical period. Developmental toxicants are agents that cause adverse effects on the development of new progeny. Recently the developmental toxicology has become an increasingly significant area of toxicology and encompasses the study of hazard and risk associated with exposure to toxicants during pre and postnatal development. It has been expanded by the U.S Environmental Protection Agency to include effects on the developmental process in the course of the time of puberty, i.e., until the completion of all developmental processes. Although considerable progress has been made in determination of causation, the etiology of the majority of birth defects is unknown or only poorly established. The present review is an effort to learn much more about the toxicant and their mechanisms involved in eliciting congenital defects. The attention has been focused on the genetic and environmental factors and their interactions involved in triggering such mechanisms.