The Conundrum of Associations
Since 1999 we have increased spending on science, as we should have, and we have seen an increase in suicides. But one has nothing to do with the other. The population has increased and suicides are proportional to population.
Consider bisphenol A, the chemical used to formulate polycarbonate plastics and epoxy resins that line food cans. It has been accused of causing everything from obesity and cancer to heart disease and developmental problems. There is indeed an association between blood levels of BPA and heart disease but that may well be because people with heart disease have consumed more canned foods with high salt and fat content. They would have higher blood levels of BPA leached from cans, but the culprit is the sugar and fat content. In fact the Canadian Food Inspection Agency carried out a survey of BPA in canned foods and concluded that an adult would need to consume approximately 14 kg of canned vegetables each day (approximately 50 servings) to reach an exposure to BPA that may pose a safety concern.
On the other hand, there are some associations that may eventually prove to be causative. FDA in the U.S. recently learned of a cluster of acute liver failure cases in Hawaii. It turned out that the cases were associated with having used a dietary supplement called OxyElitePro advertised as an aid to losing weight and building muscles. The product contained aegeline, an alkaloid extract from leaves of the Asian bael tree. Researchers believe this may be the culprit, although genetics likely play a role because most of the victims were of Pacific island ancestry. Although the case is not iron clad, the supplement has been taken off the market.
Another association that has recently been publicized is that between the murderous rage of the California mass killer Elliot Rogers and his addiction to creatine which he was taking for body building to make himself more attractive to girls. There is virtually no evidence that creatine can lead to rage like steroids can, but nevertheless the association has been widely publicized. It likely has no greater connection to causation that than that between per capita margarine consumption and the divorce rate in Maine, another spurious association discovered by the clever Harvard statistician.