ALL THE PHONE NUMBERS of your contacts are now on Facebook if u use the Facebook Apps! Go to the top right of the screen, click on ACCOUNT, click on EDIT FRIENDS, left side of screen and click CONTACTS. you will see all phone numbers from your phone (FB friends or not) are published that you have stored in your mobile phone.
TO REMOVE, go to the right column, click on “remove all your imported contacts” please repost this on your Facebook, Twitter and Google Plus status, so your friends can remove their numbers and thus prevent abuse.
Facebook also state that the information is available to you only but it also mention it can be use to made friend suggestion for you and others.