It is possible to find some information by googling an email address ... but that depends more on you registering on sites that require you give them your email address and the security the site uses to protect your email information.
Most sites require you to give them your email address in order to register (if you don't register then of course your email address is usually pretty safe, but if you use some older Internet browsers, your email address can still be "gathered" by web sites set up to do so.)
On the other hand, most web sites that require you to register also give you the option of letting everyone see your email address or keeping it hidden (always hide it, unless you're a complete idiot who loves spam.)
So short answer .. yes, it is possible, but in reality it isn't that big an issue if you take simple precautions.
As Keebler Elf suggests, having more than one email account to use for your different activities is a very good idea.