Joe Shaw's advice to consider carefully human toxicity of pesticides is probably what is uppermost in the minds of careful pesticide users. However, the toxicity of the active ingredient in the pesticide is not the only factor to consider. I had always heard that RoundUp is safe as these things go. Studies on the active ingredient of RoundUp (glyphosate) suggest that it's relatively or completely benign to humans when used as directed. But there does seem to be a link between the use of RoundUp and the precipitous decline in amphibian populations. What's surprising about this is that it's not the glyphosate which seems to be the problem. It's the surfactants used to make the RoundUp stick to leaves. Surfactants have so many industrial applications that keeping them out of wild spaces is probably impossible under present usage conditions. Those contemplating the use of RoundUp might give consideration to the greater picture: focusing on the effects of glyphosate on humans is not the whole story. Jim McKenney, Montgomery County, Maryland, USA, USDA zone 7 where there's a ten or fifteen year old jug of RoundUp - never opened - somewhere in the basement.