A number of studies, particularly those published between the 1930s and 1970s, purported to demonstrate very large benefits from drinking fluoridated water. In 2000, these studies were critically reviewed by an expert committee, the “York Review,” and found to be of extremely poor quality. The York Review found, for example, that few studies alleging benefits from fluoridation had controlled for other factors (e.g., poverty) that can greatly affect tooth decay, and had ever been a “randomized controlled trial” — the gold standard in medical research and required before most drugs can enter the market. The scientists who participated in the review, including Sir Iain Chalmers, have publicly stated their surprise at the “poor quality” of research they found.