EPIDEMIOLOGICAL INVESTIGATIONS OF POISONOUS PLANT-INDUCED BIRTH DEFECTS

I. ABSTRACT Epidemiological studies of birth defects induced by poisonous plants have encompassed not only observational studies but also analytical and experimental studies. Epidemiologic investigative techniques have been used as a diagnostic aid to determine what agent, host and environmental factors were associated with a birth defect(s) in domestic animals. Although many of these investigations included laboratory studies, they usually began with field observations on the frequency and pattern of defects in a herd or population that had grazed either in a particular pasture or over a large, defined geographical region. Epidemiologic field studies have suggested that not only the toxic plant but also man-made or other natural environmental factors were associated with defects in domestic animals. The mere presence of the poisonous plant alone was not enough; it must have been consumed. However, field investigations have in many instances been used to determine what poisonous plants probably induced birth defects in domestic animals.