I have never heard of anyone overdosing on vitimins or minerals.I guess though with the mercury scare it has become trendy to worry about overdosing on v&ms and toxins generally.Keep in mind that RDA are the minimums for sedentary people and that weight training and cycling creates a need for far more than the minimums for energy generation,tissue building/rebuilding,recovery etc.Also keep in mind our soils are becoming chronically deficient in nutrients due to shortsited agricultural techniques and selenium is frequently cited as a nutrient often missing.So those amounts of minerals may or may not actually be in the food you eat. It is interesting that more and more chronic diseases including heart disease and various cancers are being found to be associated with deficientcies with various vitimins and minerals.While I agree you should be sensible about vitimin and mineral use I feel the far greater risk is deficiency rather than overdosing