"Smartphone" dangerous? Why focus on the smartphone?
In companies, employees often share on-call phones of all kinds, typically even laptops (upon which the keyboard is a veritable cesspool of infections waiting to strike), conference bridges, projectors, even buttons on the soda machine are all more likely to get you an infection than a smart phone. At home, you share a remote control a dozen times more a night than a phone. I clean my iPhone regularly, and its nearly button free exterior means very few places for a virus to hide. When's the last time you polished the TV remote, or the land line phone, or your shared home computer keyboard, or sprayed down with lysol the seat your ass just departed?
Targeting specific things to clean for fear of viruses is the job of nut cases and those with specific medical issues. If your susceptible to colds and viruses, use hand gels and antibacterial wipes and you have little to fear that's not airborne, no matter the surface you touch. For the rest of us, being exposed to dirt, grime, and bugs is actually IMPORTANT, as it strengthens our immune system. Over-ridiculous cleaning regiments can only protect you so far (most of the bugs you can get are airborne, face it), and exposure to all that chemical can't be good for you in exchange.
I'm not superhuman, but I only get a couple sniffles a year and maybe 1 or 2 good colds. I get the flu maybe once every 7-8 years (and more often when i get the shot then when i do not.). This past year both the wife and my daughter got it, and I both had no flu shot (they did) and I didn't get it. I clean my kitchen very well (food borne illnesses are both bad and easy to prevent, but I dislike ants equally), and keep the house in general order, but I don't spray and clean every last surface for fear of infection (I clean mostly to prevent unpleasant smell and the look of disorder, not for the medicinal benefits), I only vacuum once a week and not even regularly, and we're lucky to polish the bathroom at least as often. People that i know who do clean heavily, spray everything, and waste hours a week; they are constantly sick, as are their kids.
Exposure to an infection is not a guarantee of infection. A tiny bit of care can prevent that (don't stick your fingers in your eye after touching something that doesn't belong to you personally, don't shake hands kiss or hug people visibly sick, and visit places that sick people go as absolutely infrequently as possible). However, that small exposure causes a small immune reaction, and potentially develops immunity, so later when you touch someone's phone who really is sick, and they have a cold you've previously been exposed to, you do not get sick! Taking away that exposure means you have no protections. The body was designed to fight these things, but lack of exposure not only means you have more things to be exposed to you're not immune to, but the immune system is like a muscle, and under-worked it gets weaker in general, making tho colds you get harder to get over.
Oh, and unless specifically advised by a doctor not to, breastfeed for as long as humanly possible, 2 seasons minimum. I swear, all the 0-3 month baby formula should be strictly by prescription, and the 6 month stuff used only as supplements. Failing to provide your child those immunities by personal choice should at the very least cause your insurance company to raise your rates if not come with civil penalties. It should be something only done out of medical necessity, and never choice. Don't want to feed? Don't have a child!