In reply to toad:
Untreated water, dirty bottles - and cost! Part of the arguement is that mums get given free formula for their newborns (meaning breast milk dries up), but then can't afford to buy enough formula to adequately norish their older babies.
Mind you, even in countries with sterilisers & clean water, bottle fed babies are far more likely to end up in hospital with gastroenteritis. Formula's not inherently evil (indeed, on occasion, it's mighty convenient), but it ain't as good as the real thing.......