Researchers are investigating the Potomac River's most unusual inhabitants: Male fish that grow eggs like female fish. According to an article in today's Washington Post by reporter David A. Fahrenthold, "Along the Potomac, researchers have long suspected that hormone-mimicking chemicals were the cause of the 'intersex' fish. The first of these creatures, male fish with eggs growing in their sex organs, were noticed in a rural West Virginia tributary in 2003." Scientists suspect a class of compounds called endocrine disruptors may be to blame for the intersex fish. According to the Natural Resources Defense Council, "An endocrine disruptor is a synthetic chemical that when absorbed into the body either mimics or blocks hormones and disrupts the body's normal functions." Exposure to endocrine disruptors may lead to developmental abnormalities, like those the intersex fish exhibit. The effects and identity of many endocrine disrupting chemicals are still largely a mystery to scientists and the public. Chemicals such as dioxin and DDT are known endocrine disruptors; but most chemicals are not tested for their effects on the endocrine system. Suspected endocrine disruptors can be found in pesticides, plastics, and fragrances. The Environmental Protection Agency should already have a handle on the endocrine disruptor mystery, but the agency has been dismal in researching or testing suspected chemicals. In 1996, Congress passed the Food Quality Protection Act requiring EPA test suspected substances for their effects on the endocrine system. In 2007, 11 years later, EPA finally unveiled the list of chemicals it intends to test. This is one of the most egregious examples of regulatory delay in recent memory.