Members of Congress are done waiting around on Apple to take up the casual offer from Sen. Charles Schumer to discuss the recently reported loophole in iPhone apps that gives developers access to users’ contact list and private photos. Henry A. Waxman, the ranking member of the Energy and Commerce Committee, and G.K. Butterfield, the ranking member of the Commerce, Manufacturing, and Trade Subcomittee, sent letters to 34 vendors of social apps for Apple’s iOS devices regarding their policies on collecting information from users.

Earlier this month, the New York Times conducted an experiment that discovered apps that acquired permission by the user to use the phone’s current location allowed the app developer to also access the user’s personal info, contact list, and photographs without the user’s consent or knowledge.

Recipients included the likes of Apple CEO Tim Cook, who received a previous letter from Rep. Waxman and Rep. Butterfield on March 14 seeking answers over said privacy problems, Foodspotting CEO Alexa Andrzejewski, Twitter CEO Dick Costolo, Foursquare co-founder Dennis Crowley, Path CEO Dave Morin, Hipster founder Doug Ludlow, Pinterest CEO Ben Silbermann, and a host of other people associated with apps and websites you’re likely to recognize.

The letters, which were nearly identical for each recipient, include potentially incendiary questions about the app’s user statistics – something I’d be surprised to see the app bosses readily hand over. Some examples:

Expect a lot of deferrals to a Terms of Service page from several if not all of these app developers. Curiously, no mention of Android or Google is made in the letters despite Android apps being found to also be guilty of allowing apps with the photo-accessing loophole to be distributed through Google Play née Android Market.