In this video segment adapted from FRONTLINE: “Fooling with Nature,” learn how Theo Colborn, then a scientist with the World Wildlife Fund, noticed a disturbing trend among animal populations in the Great Lakes. Colborn and other researchers, including Jim Ludwig, identified problems, from population decline to birth defects, which are caused by disruptions to the animals' endocrine systems. Certain chemicals, called "endocrine disruptors," alter embryonic growth by mimicking or blocking the body's hormones. Scientific research like Colborn's and Ludwig's raises questions: at what point is there enough scientific proof to take action, and what action should public health officials take?
For most people, the word hormones conjures images of puberty, teenage acne, and adolescent angst. But hormones are far more important than that. As the body’s chemical messengers, they regulate all the biological processes in your body, including your metabolism, the development of your brain and nervous system, and the growth and function of your reproductive system. And when hormones are disrupted, many things can go awry.
Hormones are part of the endocrine system, the body’s network of glands, hormones, and receptors. Glands release hormones that travel throughout the body, reacting with cells containing matching receptors, much like a key fitting into a lock. When a hormone binds with the receptor, the hormone's molecular instructions are transmitted to the cell's inner workings.
Because hormones contribute to so many areas of growth and development, chemicals that disrupt the endocrine system can have far-reaching effects, from developmental delays to birth defects. Some chemicals, like certain pesticides, have been found to disrupt the endocrine systems of animals in laboratory studies, and chemical exposure has been linked to problems in wildlife in certain locations. The link between environmental chemicals and endocrine system diseases in humans, however, is still poorly understood and scientifically controversial.
Perhaps the most famous endocrine disruptor is Bisphenol A (BPA), an industrial chemical found in many hard plastic bottles and metal food cans since the 1960s. So far, toxicology tests have yet to prove that BPA is harmful to humans. However, some recent studies have shown subtle effects in laboratory animals at very low concentrations, raising concerns about the potential effects of BPA on the brain, behavior, and prostate gland in fetuses, infants, and young children. This is where the precautionary principle comes in: with the scientific risks still unclear, what should the government do? The U.S. government has not banned BPA, but it has taken steps to reduce human exposure in the food supply. For example, it supports industry moves to end the manufacture of baby bottles and infant feeding cups that contain BPA.
To study the risks of other potential endocrine disruptors in the environment, the Environmental Protection Agency (EPA) established a program called the Endocrine Disruptor Screening Program, which chooses chemicals for screening and testing, develops tests, and implements policies and procedures regarding these chemicals. But there is a lot of work to be done. There are an estimated 87,000 chemicals produced today, and scientists don’t have enough data on most of them to conclude if they are endocrine disruptors.
It is known, however, that many chemicals, including some in pesticides and plastics, are potential endocrine disruptors. There are a few easy things you can do to reduce your exposure: eat organic produce when possible, and wash or peel nonorganic fruits and vegetables; avoid areas freshly sprayed with pesticides; and heat food in the microwave in ceramic or glass—never in plastic.
Academic standards correlations on Teachers' Domain use the Achievement Standards Network (ASN) database of state and national standards, provided to NSDL projects courtesy of JES & Co.
We assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. If a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by ASN or by Teachers' Domain. We will be adding social studies and arts correlations over the coming year, and also will be increasing the specificity of alignment.