Persistent organic pollutants (POPs) include several groups of chemicals with similar structures and physical-chemical properties that elicit similar toxic effects. They have been used worldwide in agriculture (pesticides), industrial and health applications. Some POPs mimic natural hormones and are defined as endocrine disrupter compounds (EDCs), meaning that they are able to interfere with functions of the endocrine system; in fact, damage to the endocrine system is the first detectable effect. Non-pesticide EDCs are oestrogen agonists or antagonists, and as such may be responsible for the recent increase in reproductive pathologies in many species, including humans.
The link between EDC exposure and effect is not always clear or easily demonstrable; in fact the causes of health and reproductive problems in humans and wildlife are often difficult to understand, because many factors contribute to them. A link has been demonstrated, however, in accidental exposure to xenobiotics and the causation of health problems, including reproductive impairments in people exposed to them. Evidence of reproductive problems has also been reported in wildlife. Numerous experiments demonstrate the link between EDC concentration in tissues and reproductive impairment. EDC contamination is responsible for reducing sperm count and quality, female fertility and sex ratio. It is also responsible for inducing several types of cancer in both the male and female reproductive systems, and in these cases infertility may be a consequence of the cancer.