In America, chemicals are innocent until proven guilty. It’s a rule that’s been in place for one hundred years and still applies to compounds used every day in industry and in your home.

This may be changing at last. In April Congressman Henry Waxman, chair of the House Committee on Energy and Commerce, made regulation of toxic chemicals a priority by proposing the Safe Chemicals Act of 2010. A companion bill was introduced in the Senate by Frank Lautenberg.

Under Waxman’s legislation, the Environmental Protection Agency would at last gain some real powers to control the chemical soup we live in. Manufacturers would be required to test their chemical products. Procedural obstacles that have hobbled regulators would be swept away. Vital safety information could no longer be kept secret. Testing of especially dangerous products would be required within eighteen months.

The initial lack of public attention to the Waxman bill should not obscure its importance in a world whose chemical complexity we have only started to comprehend. Chemical manufacturers publicly support the bill, but the industry is already working to weaken some provisions. The experience of health care reform proves that even a watered-down version of the legislation could be killed in the partisan atmosphere of the current Congress.

 THIS LEGISLATION moves us forward along a path that began in the first months of the twentieth century, when advances in science and industry brought the problem of chemical safety to the world. Legislators began to worry about toxic chemicals when a strange plague struck England 110 years ago. Seventy died, and many more became ill, poisoned by a commercial chemical that had inadvertently entered the food supply.

The English malady, diagnosed rapidly as arsenic poisoning, was tied to certain brands of beer. A Royal Commission of five scientists was empanelled to find the causes and prescribe remedies. At its head was the famous physicist Lord Kelvin, by then approaching eighty years of age, framer a half-century earlier of the Second Law of Thermodynamics, inventor of the absolute temperature scale, and designer of the first transatlantic telegraph cable.

Kelvin and his colleagues traced the impurity to its origin. Until a few years earlier, a beer purity law like those still extant in Germany today had allowed only natural ingredients. But the law was repealed in a parliamentary deal to pass a controversial tax increase. Brewers began using acid to quickly digest starchy grains. The source of England’s problem was contaminated sulfuric acid, made from batches of imported pyrite that were unusually rich in arsenic.

This finding brought the Royal Commission to what was then a novel question: how much arsenic should be allowed in food? Science alone offered no answer. Chemists of the day succeeded in measuring the poison in the beer that made its drinkers ill. But the investigators did not know whether smaller quantities, consumed over a lifetime in each glass of beer, would cause illness too. They had no choice but to balance the public’s health against uncertain dangers.