| > but in what other contexts do we tell people: the studies don't show harmful effects at low levels, but you shouldn't do it anyway because the studies haven't proven there aren't harmful effects at low levels. A specific 'health and safety' context where this exact issue comes up is actually with ionizing radiation (such as from nuclear reactors). Humans (like most animals) actually have a remarkable ability to overcome low levels of radiation damage, by means such as genetic repair, programmed apotosis (essentially ASSERT()s in your own genetic code), and even roving patrols by your immune system that catch pre-cancerous cells. The problem is that it is difficult to determine whether there is a real low-dose threshold, below which people do not suffer appreciable increase in health risk from radiation. Also, whether that threshold depends on the person, depends on prior exposure, depends on type of dose received, a combination of the above, etc. The evidence leans heavily to there being a threshold much higher than the levels of radiation we'd ever encounter in day-to-day life (and possibly even there being a beneficial effect to low levels of radiation). But our radiation health physicists (and UN health organizations) have tended to take a very conservative view and simply recommend that people minimize radiation exposure, at least until there is enough evidence to make very clear what a safe threshold level is. |