Reader call: nailbiting and how long to keep formula

Jennifer writes:

"My daughter is turning 3 next week.
For her first year and a half of life, I always trimmed her nails
while she was a in a "milk coma" while nursing.  Once she
weaned, Daddy would read her a book while I quickly cut her nails.  She
didn’t seem too bothered by it.  Then, around Christmas this past
year, she began biting her fingernails, and occasionally her toenails.
She now rarely bites her toenails as we keep her in socks all the
time, including overnight.  For her fingers, we have tried the "Thumbz"
liquid painted on her nails, tried bribing her with fingernail polish if
she let them grow, ignored the behavior.  We don’t know what to do.
We haven’t had to trim her nails since Christmas because she keeps
them chewed down.  Help!"

We have the exact same problem here with my older son. He bites his nails (not until they bleed, just down to the tip of the finger). I have no idea what to do about it, because I bite my nails, too, and have for as long as I can remember. I’ve gone through 6-month periods of getting regular manicures and having nice nails, but then I always go back to biting them. I think it just bugs me to have any white sticking out from the tip of my finger.

Does anyone have any ideas to help preschoolers and middle-aged moms stop biting their nails?

On a totally different topic, Michele writes:

"I fed my first son expressed breast milk (he never latched) and was always amazed at how I could leave breast milk out for hours without worrying about it spoiling. My second is formula fed, and I want to know how long I can *really* leave out formula before I should worry. I realize it’s different than breast milk, but come on! 2 hours? This stuff is expensive and my baby will sip an ounce and then drift off to sleep. If I throw away every half-finished bottle, that’s a lot of money down the drain!

Of course the formula companies want me to toss it…. then I buy more! What do you think?"

I think formula is too expensive and if I ran the world I’d change a whole lot about how it’s priced and marketed, but that’s neither here nor there.

I have no firsthand knowledge of storing formula. I did take a food safety course in culinary school, and that makes me think there’s probably a difference in how the formula’s been treated that would determine how long you can realistically leave it out. For example, if you pour ready-to-eat formula straight into a sterilized bottle you should be able to leave that out longer than if your baby was dawdling on and off eating formula you mixed from powder with tap water and put into a bottle you’d rinsed out well but not put through the dishwasher.

Dr. Sears’ The Baby Book says (italics are theirs):

It is all right to reunse leftover formula within a few hours if it is immediately refrigerated after the first use. Cap the bottle to keep the nipples clean. For maximum safety, however, do not reuse leftover formula, because bacteria may have been introduced through baby’s saliva. Do not use leftover formula that has been unrefrigerated for more than three hours.

So they’re telling you you can leave it out for almost three hours, which would give a bigger window for refrigerated formula. You’re probably also going to be way more anal about not keeping formula with a newborn than you would be with an older baby with a stronger immune system.

But there’s a lot of grey area there. Anyone with practical experience or other (neutral) guidelines?