Why are endocrine-disrupting substances phase-out substances?
Substances that affect the hormonal systems can cause harm to organisms, populations or ecosystems. Hormonal (endocrine) regulation is one of the organism's most important means of maintaining physiological equilibrium. Furthermore, reproduction physiology, including foetal development, is largely hormone-controlled. Well-functioning endocrine systems are thus a prerequisite for maintaining many physiological functions of mammals, other vertebrates and even lower animals.
Substances that disrupt the balance of the body's hormonal systems can give rise to a number of different effects such as toxicity to reproduction (disruption of reproduction or deformity), cancer, diabetes, cardiovascular diseases, brittle-bone disease and damage to the immune system and the nervous system, of which the latter in turn can lead to effects on behaviour.
It is important to note the difference between individuals as regards sensitivity and possible effects of exposure to endocrinologically active substances during the period as an embryo, foetus and child compared with exposure during adult life. In early developmental stages, even a brief exposure to endocrine-disruptive chemicals at sensitive junctures can give rise to permanent changes. This can become manifest later in life. The background to this sensitivity during foetal development is that the hormonal signal systems during this period have an organizing and differentiating function. This means they have a potential to cause lasting harmful effects on the development of e.g. the genitals, the brain, the thyroid gland, the immune system and the liver. In the adult individual, hormones generally have an activating action, which primarily results in transient changes that are reversed when the exposure ceases. More long-lasting and high-level exposure of adults is probably required to cause irreversible damage, such as cancer.