On the first Earth Day, the U.S. was a poi

题目：

On the first Earth Day, the U.S. was a poisoned nation. Dense air pollution blanketed cities like Los Angeles, where smog alerts were a fact of life. Dangerous pesticides like DDT were still in use, and water pollution was rampant—symbolized by raging fires on Cleveland’s Cuyahoga River. But the green movement that was energized by Earth Day— and the landmark federal actions that followed it—changed much of that. Today air pollution is down significantly in most urban areas, the water is cleaner, and even the Cuyahoga is home to fish again.

But if the land is healing, Americans may be sickening. Since World War Ⅱ, production of industrial chemicals has risen rapidly, and the U.S. generates or imports some 19 billion kg of them per day. These aren’t the sorts of chemicals that come to mind when we picture pollution—huge plants spilling contaminated wastewater into rivers. Rather, they’re the molecules that make good on the old "better living through chemistry" promise, appearing in items like unbreakable baby bottles and big-screen TVs. Those chemicals have a, habit of finding their way out of everyday products and into the environment—and ultimately into living organisms. A recent biomonitoring survey found traces of 212 environmental chemicals in Americans—including toxic metals, pesticides, etc. "It’s not the environment that’s contaminated so much," says the director of the Cincinnati Children’s Environmental Health Center. "It’s us."

As scientists get better at detecting the chemicals in our bodies, they’re discovering that even tiny quantities of toxins can have a potentially serious impact on our health—and our children’s future. Chemicals like bisphenol A (BPA) and phthalates—key ingredients in modern plastics—may disrupt the delicate endocrine system. A host of modern ills that have been rising unchecked for a generation—obesity, diabetes, attention-deficit disorder —could have chemical connections. "We don’t give environmental exposure the attention it deserves," says Dr. Philip Landrigan. "But there’s an emerging understanding that kids are uniquely susceptible to environmental hazards."

Washington has been slow to arrive at that conclusion. The Toxic Substances Control Act (TSCA), the 34-year-old vehicle for federal chemical regulation, has generally been a failure. The burden of proving chemicals dangerous falls almost entirely on the government. And the Environmental Protection Agency (EPA) has been able to issue restrictions on only a handful of chemicals and has lacked the power to ban even some dangerous cancer-causing substances.

But change is coming. The Obama Administration is taking a closer look at chemicals. More important, Congress may finally be ready to act. "We can’t permit this assault on our children’s health—and our own health—to continue," says Senator Frank Lautenberg.

As to the chemical problem, the author holds in Paragraph 4 that（）

A. Washington has successfully made some federal chemical regulations

B. the EPA has issued restrictions on various chemicals

C. Washington was slow to realize the problem and take measures

D. the government should take all the responsibility for proving dangerous chemicals