Featured Questions, Comments and Responses

Question: Do dioxins have adverse health effects on endocrine modulation? If so, how do the effects vary if the individual was exposed prenatally, postnatally, or during development up to puberty?
Brian, Tufts University

Answer: Thank you for your question. Endocrine modulation or disruption, is interference with the synthesis, secretion, transport, binding, action or elimination of natural hormones in the body by an exogenous agent. By disrupting or modulating the normal function of the endocrine system, adverse effects on the reproductive system or other hormonally-dependent systems may occur.

Dioxins, PCDDs and PCDFs, are considered by many to act as endocrine disrupters. Dioxins are by-products of industrial and thermal processes. Classes of dioxins also include PCBs. Dioxins such as TCDD are believed to act on the aryl hydrocarbon receptor (AhR). Agonists of AhR are able to produce broad spectrum effects by interacting with multiple signaling pathways and inducing or inhibiting multiple gene products.
The next part of your question addresses 'critical windows of development' which is discussed on the EM-COM website http://www.emcom.ca/EM/windows.shtml
Generally, periods of formation of endocrine organs or pathways and systems requiring hormonal regulation would be susceptible to the effects of endocrine disruption. These critical periods occur prenatally during gestation at which time development of major organs and systems is occurring. However, some systems continue to develop during early childhood through to adulthood. Production of semen, for example, is a hormonally dependent-process that can be disrupted during adulthood by certain exposures. For further details regarding these critical windows of development, please see the EM-COM website (above link) and examine all graphics regarding male and female development.