Hi - here are some links that will allow you to explain to patients about the risks of formula feeding. We were talking on another thread about how it is not true to say that 'breastfeeding is good, but formula is not harmful'. Studies I am linking to here control for socio-economic effects and other variables.
pediatrics.aappublications.org/cgi/content/full/99/6/e5 shows the 'dose response' effect of formula - the more formula used, the greater the risks to health
pediatrics.aappublications.org/cgi/content/abstract/119/4/e837 is from a massive UK study, showing the risks of hospitalisation are greatest with formula feeding, and lessen with partial formula feeding, but any formula feeding increases the risks compared with no formula feeding
pediatrics.aappublications.org/cgi/content/abstract/117/2/425 shows the risk of respiratory disease increases with the introduction of any formula
www.drjaygordon.com/development/bf/sciencebf.asp has some good links which look at risks of formula
Some of the risks of formula are associated with 'not breastfeeding' - that is, the risks are there because the breastfeeding protection isn't there. But that is the same as intrinsic risks of formula, because in a young baby, formula is always a replacement for breastfeeding ie the more formula he gets, the less bf he gets.
Other risks are intrinsic to the formula itself - the use of the formula passes on pathogens to the baby (and the baby has less protection from them if he is not bf at all, but some protection if he is - probably accounts for some of the difference between the partially formula fed babies and the fully formula fed babies).
Expressing this to parents should be done sensitively, obviously, and they may need to know the concept of risk a bit better, but reassuring people there is no risk to using formula is to mislead them - what do you think?