DDE reduces medullary bone formation in birds

Abstract

DURING the past two decades residues of certain chlorinated hydrocarbons, especially DDT, have caused declines in the populations of various carnivorous birds in the North Temperate Zone by reducing their reproductive success 1-3. Contaminated birds lay eggs with abnormally thin, insufficiently calcified shells, so that there is increased egg breakage and embryonic death4-9. Although adult mortality, abnormal behaviour, delayed ovulation and nesting, egg eating, and failure to lay eggs also sometimes result from such contamination1-3,8-11, the thin eggshell phenomenon is the chief cause of the declines in population3,6,8. © 1971 Nature Publishing Group.