The impact of endocrine disruptors on oocyte competence

To date, approximately 60 chemicals have been identified as endocrine disruptors: exogenous agents that interfere with various aspects of natural hormone physiology. The potential reproductive and health hazards of these environmental chemicals have recently generated concern among the scientific community, policy makers and general public. The present review presents and discusses the available evidence that environmental chemicals are causing ovarian toxicity in various species, with particular attention to farm animals. The impact of chronic exposure to endocrine disruptors via food and drinking water cannot be neglected when studying fertility problems in these species. This review focuses attention on the superfamily of organochlorine chemicals, persistent organic pollutants (POPs), because of their persistence in the environment, ability to concentrate up the food chain, continued detection in environmental matrices and ability to be stored in the adipose tissue of animals and humans. Published data clearly indicate that POPs disrupt mammalian oocyte maturation and follicle physiology in every species studied so far, including farm animals. However, as most of the data available still derive from experiments performed on laboratory species or in vitro models, great care should be taken when extrapolations to other species or environmental situations are attempted.