This site has been somewhat inactive for too long, but is gathering steam again. While it is undoubtedly better to keep up the pressure, safety of the future brains is also a long-term investment that will generate benefits for decades to come. So where do we stand regarding chemical brain drain today? The good news is that there is additional research focus on the vulnerability during early development, in particular sensitive stages of brain development. However, when using the PubMed data base of the National Library of Medicine, the results are not all that encouraging. Articles in scientific journals can be categorized into a field called “prenatal exposure delayed effects”. From about 1990, at least 100 articles every year focused on the adverse effects of toxicant exposures incurred during early development. Ten years ago, the number had risen almost to 400, and the average for the most recent five years is about 700 (dark columns in below figure), although possibly slightly decreasing. Importantly, the number of such articles that focused on adverse effects in humans in epidemiological studies has been increasing, now showing a doubling from the 20% level ten years ago (pale columns). But the bad news is that only a dozen or two focus on the brain (small, black columns). Thus, the library classification suggests that very few articles focus on chemical brain drain in humans. That may be an exaggeration, but of course more research is needed. Brain toxicity was a major focus of the PPTOX conference in May. Still, while documentation of brain vulnerability to toxicant exposures is growing, studies that follow children from birth and onward are expensive, and it takes a long time for the research to be completed – and recognized as documentation of the need to protect developing brains. Just think of the growth of knowledge on mercury (or, rather, the methylmercury that is accumulated in the marine food chain). By now, we know much about the dose-dependent effects on brain development. But what about longer-term adverse effects, such as degenerative diseases and ageing? Clearly, we don’t know very much, because the studies have not yet been carried out. That does not mean that early-life exposure to mercury is innocuous in regard to the ageing of the brain. One recent publication describes the fate of Minamata disease victims. They first suffered serious impact on their cognitive and motor development, with symptoms not unlike spastic paresis and mental retardation. Now that the patients are in their 60s, they are rapidly deteriorating, and most of them are now confined to wheelchairs. So the normal ageing had a greater impact on the victims, perhaps because they possess little buffer or reserve capacity to withstand the effects of normal age-related cell losses in the brain. So this information is now emerging 60 or more years since the discovery of the Minamata epidemic. The delay in recognition of neurotoxic impacts is perhaps unusually long, but it emphasizes the time scale that we must deal with. Exactly because of the delayed documentation, intervention will be similarly delayed or even more so. Given the life-long impact of developmental neurotoxicity, the prudent prevention policy would have to be more rigorous in order to catch up. The fact that the scientific evidence is not yet at hand does not mean that there is nothing to find. Nowhere in public health and health policy is the time scale more important than in chemical brain drain.