In 1998, a laboratory accident in Dr. Pat Hunt's lab alerted her and many other scientists to the dangers of even tiny amounts of certain chemicals present in many of the products we use.

When a temporary employee mistakenly used a harsh alkaline floor detergent to clean the cages of the mice she was studying, the animals' eggs began to develop serious chromosomal problems. The detergent caused the plastic in the cages to begin to disintegrate, which allowed a chemical called bisphenol A -- an endocrine disruptor -- to leach into the animals' food and water.

Dangerous to Children

Endocrine disruptors are present in many household products. These man-made chemicals affect the hormones that control development and function in our bodies. There is mounting evidence that they can cause harm in the development of fetuses and children, who are particularly sensitive to the chemicals because they have not yet developed the protective mechanisms present in adult bodies.

Disruptors Everywhere

Endocrine disruptors come from many sources:

• Bisphenol A, a common ingredient in many plastics, including those in reusable water bottles and resins lining some food cans and dental sealants, can change the course of fetal development in a way that increases the risk of breast cancer.
• Exposure to phthalates can lead to incomplete testicular descent in fetuses. Phthalates are found in vinyl flooring, detergents, automotive plastics, soap, shampoo, deodorants, fragrances, hair spray, nail polish, plastic bags, food packaging, garden hoses, inflatable toys, blood-storage bags, and intravenous medical tubing.
• Perfluorooctanoic acid (PFOA), found in grease- and water-resistant coatings like Teflon and Gore-Tex, is a likely carcinogen.
• Runoff from parking lot sealant is a source of polycyclic aromatic hydrocarbons, which are likely carcinogens and possibly reproductive toxicants.
• An insecticide called methoxychlor and a fungicide called vinclozolin caused changes to male mice born for as many as four subsequent generations after the initial exposure.

You Have Been Exposed

Only in the past five years or so have scientists developed tests sensitive enough to measure the very low doses of these chemicals present in our bodies and the environment. They found that phthalates and PFOA are present in nearly everyone.

"They're all around us," said Dr. Shanna Swan, a phthalate researcher. "In food, in household dust, and in products, but they're invisible. People don't know when they're exposed."

The technology currently exists to make products such as plastics that do not contain endocrine disruptors. However, it may be difficult to convince industry manufacturers to make the switch.