Prenatal Origins of Endocrine Disruption
Critical Windows of Development
WHY IS THIS IMPORTANT?
Why create the Critical Windows of Development?
Why are we seeing record numbers of asthma, autism, breast cancer, childhood diabetes, endometriosis, immune system disorders, learning disabilities, and prostate cancer (as well as many other diseases and disorders). While diet, lifestyle, and longer lifespan account for some of the increases, they don’t tell the whole story. Think about the recent explosion in these maladies and think about how it coincides with the widespread and unavoidable presence of endocrine disrupting chemicals in our lives. Then think about the fact that research clearly shows that endocrine disrupting chemicals harm the health and development of animals studied in the lab. We created the Critical Windows of Development to make you aware of this research, and to make you think about reducing your exposure to endocrine disrupting chemicals, because disease prevention is much smarter than disease treatment.
Why are low doses so important?
The issue of low-dose effects is relatively new and somewhat complex. Scientists typically test substances for toxicity using a wide range of doses. The highest dose that has no harmful effects is called the ‘No observed adverse effect level’ (NOAEL). To arrive at a level of exposure considered “safe,” the government takes the NOAEL and reduces it by several safety factors. Our relatively recent ability to detect endocrine disrupting chemicals at extremely low concentrations threw a monkey wrench into this process. When effects were studied at extremely low doses (well below supposedly “safe” levels of exposure, for example, in parts-per-trillion) not only were adverse effects found, but the results were sometimes different than what was found at higher doses. It has become clear that the process of determining “safe” levels of chemical exposure is flawed and that chemical testing protocols need to be revised to include testing for low-dose effects.
Why focus on prenatal exposure?
The Critical Windows of Development was created to present the research on low-dose exposure to endocrine disrupting chemicals during development, a time when the organism is extremely vulnerable. Unfortunately, the placenta does not fully protect the baby from chemicals in the mother’s body and exposure during prenatal development can be more devastating than adult exposure for several reasons. The barrier that protects the brain from chemicals in the blood is much more permeable than it is in adulthood and the liver may be too immature to detoxify the body of harmful chemicals. Most importantly, the embryo and fetus are undergoing a period of extremely rapid cell differentiation, tissue construction and brain development. Improperly differentiated cells pass on bad programming to their numerous descendent cells, potentially resulting in poor function or malfunction throughout life (or only expressed later in life). In many instances, damage done prenatally is irreversible.
Why use animal studies to understand humans?
For decades scientists have relied on animal research to understand adverse health effects in situations where it would be dangerous to test a substance directly on humans. In fact, the major governing bodies in the U.S. that create regulations to protect our health, including the FDA and EPA, regularly use animals to test for chemical effects. It would take decades to conduct even one human experimental study on the link between prenatal exposures and adult disease. Human epidemiological studies on the correlation between adult disease and prenatal exposure are challenged by the ability of subjects to know or recall whether they were exposed in the womb. Until a better method is developed, we must rely on animal research, as we have for decades, to forecast potential health effects in humans.