on the broadcast tonight, cell phones and cancer. the issue in the news tonight because of a new statement about cancer risk. the issue so many people have suspected for years. catch her if you can. what is sarah palin up to? after a wild ride in a bus with the press in tow, where will she turn up next, and what's the point of it all? the new low for the housing market. worse now in most big cities than it was at the height of the recession crash. and the class of 2011. tonight, our annual look at the very best of the send-offs to this year's graduates. very best of the send-offs to this year's graduates. "nightly news" begins now. captions paid for by nbc-universal television

good evening. the world health organization today said cell phones are possibly carcinogenic. and they put cell phone use in the same category as contact with various chemicals for the possible cancer risk it could pose when the cell phone is pressed to the ear during use. this statement from the w.h.o. makes this topic front and center once again. this statement labeling cell phones as a possible carcinogenic hazard comes from a panel of 31 scientists. and while it doesn't reverse any of the current studies, it does raise big questions about safety and long-term effects, and it's where we begin our broadcast tonight with our chief medical editor, dr. nancy snyderman. nancy, i'm not a scientist, but reading through this stuff, it appears to be saying it can't be good for you. which is what a lot of people walk around assuming anyway.

>> i think that's where the confusion starts, brian, because it's the conventional wisdom. and these 31 scientists that you mentioned from 14 countries advised the world health organization, and they said, look, we know that cancer and asbestos are known carcinogens, but now we've studied everything from the radio waves of cell phones, tvs, transmitter towers, and the concern is is there a link? to date there is no definitive evidence linking cell phones to cancer. but then a big hedge from this group, saying that there may be enough evidence and maybes and coulds and possibilities that they have now put this in a group that includes other carcinogens, things like chloroform, cleaning fluids that you use at your dry cleaner's, gasoline fumes, and even the occupational hazards of being a carpenter, a firefighter, or a dry cleaner. but we also heard counter from the cell phone industry, and

they said that in fact there is no real concern and this classification really does not mean that cell phones cause cancer and went on to say that the fda has stated that the weight of scientific evidence has not linked cell phones with a health problem. and i think that's where you're going to see these two sides really sort of stake ground. the real gulf between them is where is the science. and i think no one has seen that definitive proof yet. >> and the questions all seem to be about could these tumors be long term, and so the science hasn't caught up with reality. and then the experts always say at the end, probably a good reason to use hands-free. >> you just said something really smart, and that is 5 billion people around the world use cell phones and yet the gliomas, these brain tumors everyone's worried about, those numbers haven't budged up at all. so that's why they're saying if you're concerned take your cell phone away from your ear, use

handheld, and for heaven's sakes, there are probably more people who die every day by driving and texting and talking. that's the bottom line for right now. >> a good note to end on as we learn more about this. dr. nancy snyderman, as always, thanks. >> you bet. we turn now to politics. sarah palin spent the day the way she spent yesterday. on a bus ride, taking the media along for a ride, stopping at sites of historical significance, drawing crowds, talking to folks, mostly getting attention, as she is right this very minute, and causing people to ask what she's up to, as we will in a moment. tonight our chopper here in new york found the bus in a jersey city parking lot, not moving, at least for the moment. so first we start with how an alaska politician ended up in jersey by way of philly, and that job tonight falls to nbc's mike taibbi. mike, good evening. >> reporter: good evening, brian. how are you? i'm outside the liberty bell in

philadelphia, sarah palin's last stop before heading up the turnpike, a trip you know well, to get to new jersey. but if this is really the run-up to an actual campaign for the white house, brian, this is as odd and unconventional a political trip as anyone can remember. which is just the way sarah palin says that she'd want it to be. >> thank you so much for your help today. >> yes. >> reporter: outside her hotel after visiting the gettysburg battlefields, sarah palin autographed anything put in front of her, including a t-shirt worn by one fan, and in one of her few statements to a press corps straining to follow her said once again she hasn't made up her mind about running. >> i don't know. i honestly don't know. it's still, you know, a matter of looking at the field. >> reporter: her "one nation" tour began with a motorcycle ride outside the pentagon on saturday. >> how are you? >> reporter: and by its conclusion will reportedly take her from washington, d.c. to new hampshire, where she's posted no schedule for reporters to follow. no need, she said. >> i'm having a great time with our family and our alaskan friends and our pennsylvania friends who have met us here today. >> sorry. >> reporter: however, the

political reality is that even though in recent polls more than half of those questioned view her unfavorably she inspires passionate support among her conservative base, including those who couldn't get close to her at the liberty bell. >> go all the way, sarah! >> reporter: on this trip, though, she's mostly been stopping, briefly and frustratingly for the press, at historical sites like the liberty bell. before that it was gettysburg and baltimore's fort mchenry. and with reporters and photographers scrambling to keep up by convoy, even by air, and the occasional coffee shop. >> thank you, guys. did you get my coffee? >> reporter: it was a cat and mouse game with the press by design, which her supporters said made no difference. >> even without telling people where she's going everyone's finding her. so i think she's a really important person for the conservative movement and i really hope she runs. >> reporter: there's that question again. will she or won't she? >> when will you decide, governor? >> reporter: and once again the same answer. maybe. >> truly there is still a lot of time for folks to make up their mind and jump in and get their

campaigns together. the field isn't set yet. not by a long shot. >> reporter: well, as the chopper saw, palin and her family have now checked into that hotel in jersey city, which is just in shouting distance of ellis island, liberty island, likely stops on tomorrow's agenda. but first tonight, dinner in manhattan with another would-be contender for the gop nod, who turned out to be a pretender, donald trump. brian? >> oh, just too much rich material there, mike, but we're going to leave it right there anyway. mike taibbi at the liberty bell in philly. one of the stops along the cavalcade today. mike, thanks. well, whether sarah palin is running or just wants to be heard or just likes the attention, you could argue none of this would be happening if there was an overwhelming favorite for the gop nomination. tonight our chief white house correspondent and political director chuck todd has the story of the rest of this unsettled field. >> reporter: whether she's running or not, sarah palin is shouting the message that others have been whispering for weeks.

the party wants more choices. >> you know, i believe that there are many more out there who have much more to add. and competition breeds success. >> reporter: but the folks already running, like former minnesota governor tim pawlenty, are growing tired of the who else question. >> whoever's going to get in i hope they get in soon because i want the field to be set so we can have the real debate. >> reporter: one reason palin and others are clamoring for more candidates, neither pawlenty nor former massachusetts governor mitt romney is firing up the republican base. romney's answer today? tougher rhetoric aimed at president obama. >> he's been one of the most ineffective presidents at the job at hand that i've ever seen. >> reporter: hoping for an opening, former pennsylvania senator rick santorum and minnesota congresswoman michelle bachmann are expected to join the race soon. >> we're very close. i have just announced on thursday that i'll be making my announcement in the state where i was born, iowa, and in the city of my birth, which is waterloo, iowa. >> reporter: but these candidates and others, including jon huntsman, newt gingrich, and herman cain --

♪ coming to town like a hurricane ♪ ♪ herman cain -- all have failed to seriously challenge romney's shaky front-runner status. >> do i think i can win iowa? can i win iowa? [ applause ] >> the front-runner is in the mid teens in a lot of these polls and you would think a front-runner should be further ahead by this point. >> reporter: the field of non-candidates still pondering is no less crowded. there's wisconsin congressman paul ryan. he says he's 95% certain he will not run. texas governor rick perry, who said last week he's now thinking about it again. and new jersey governor chris christie, who tonight is hosting a dinner for iowa republicans, who are trying to get him in the race. >> there's a huge vacuum somebody's going to fill, particularly that social vacuum. >> reporter: that dinner of palin and trump is not the most important political dinner tonight. it is what's going on in new jersey, brian, with chris christie. his wife's at the dinner. this is a big deal. iowans are very serious about this. and he's very serious, at least in listening.

>> all right. a lot of moving parts, and we're still a long ways away. chuck todd in washington. thanks. now we turn to the economy and the thump of bad news today concerning just how bad the housing crisis is across this country. the index numbers out today show prices in 18 of the 20 cities they tracked fell in march. prices in 12 cities have hit their lowest level since the housing bubble burst. and it was supposed to get better, remember, not worse. nbc's john yang reports from one of those cities, chicago. >> the unit's leasing at 1400 per month. >> reporter: as a real estate broker aaron galvin sees lots of potential homeowners choosing to become renters instead. >> the number of people who are able to buy, qualified to buy, and really would like to buy, but the uncertainty in the market is making it just too difficult to pull the trigger. >> what color this? >> reporter: he speaks from experience. when his daughter mia was born 20 months ago, he and his wife, amy, needed more room. but they couldn't sell their two-bedroom condo.

>> we decided to rent a three-bedroom, which afforded us the space to let mia run around, grow, and see what happens next. >> yay. >> reporter: overall, home prices have plunged 1/3 since their peak in july 2006. home ownership has dropped sharply, too. according to the census bureau, it went from an all-time high of 69.2% in 2004 to 66.4%, the same rate it was in 1998. >> americans used to see financial stability in owning a home. today americans see financial risk. >> reporter: housing prices are being pushed down by the glut of nearly 2 million foreclosed homes. at the current pace that backlog would take three years to sell off. analysts say a housing recovery depends on more jobs and economic growth. >> well, many people were saying that spring 2011 was going to be the turning point.

i think we've postponed that to spring 2012. when hopefully we'll see a bottom. >> good girl. >> reporter: austin clark and her fiance were homeowners in nashville and lost money when they sold to move to atlanta. they've decided to rent and postponed buying a piece of the american dream. >> that's something that we still aspire to, but i think that right now it's still an aspiration. it shouldn't be a reality. >> reporter: retirees are being touched by this, too. many are choosing to sell their homes now rather than risk having their nest egg shrink even more. brian? >> john yang in chicago for us tonight. john, thanks, as always. when we come back here tonight, the extraordinary coming together in joplin, where all creatures, great and small, are pitching in to rebuild. and later, all they need now is a job, but they sure got a great send-off. tonight, our tribute to the class of 2011.

it's now been nine days since that tornado of historic strength hit joplin, missouri.

and in addition to the hundreds of buildings and schools that were wiped out and the town hospital, we now know some 8,000 dwellings, homes and apartments, were also damaged or destroyed. that means a lot of folks tonight are still looking for a home. nbc's ron allen is in joplin again for us tonight. >> reporter: after a sixth and final search of these decimated neighborhoods, officials say their rescue efforts will cease. the death toll has settled around 140. one huge challenge survivors now face? putting roofs back over their heads. >> it's so hard. i mean, we're just trying to get through the physical and emotional part of it. but -- >> reporter: tina dudley lost the home she rented, one of about 8,000 buildings destroyed in the storm. in a dense residential area. they're still counting how many thousands of families need homes. dudley says the only available places she's found are 30 miles away. >> we need housing, but we've also lost our cars to get to our

jobs. so we kind of need to stay close. >> reporter: fema is looking for houses within 50 miles. and neighbors elect to bring in those temporary trailers used in places like new orleans after katrina. >> we want to work hard along with the city to enable people to stay as close to the city of joplin and duquesne as possible. >> reporter: meanwhile, joplin lifts itself from the debris with every means possible. even an elephant from a circus that happened to be in town. there's progress. the main hospital back open. now a 60-bed mobile clinic. the heavily damaged home depot sells supplies in the parking lot while it builds a new store. joplin's high school has become a place of hope. >> we lost a home. we lost our cars. we lost everything. but the business is what we're after first. >> reporter: like so many here, the habidi brothers, repairing their battered family restaurant, can see a much better day. >> we just want to be part of this again.

we can do it, and we're looking for a grand reopening soon. >> reporter: however, there's still devastation as far as the eye can see here. and they're planning to start trying to haul some of this away beginning later this week. brian? >> ron allen in joplin tonight. we're thinking about them every day. ron, thanks. when we come back here tonight, the hangover enjoyed by millions of americans this past weekend.

andy robustelli has died. the hall of famer was among the best defensive players in the history of football. he played nine years with the new york giants alongside the likes of gifford, grier, huff, and katcavage. he was a father of nine who was older than most of his teammates because of his navy service in world war ii. andy robustelli was 85 years old. a big sign of the full-throated power of the movie industry this past holiday weekend. here's where your money went. "hangover 2." a big number one, despite some tepid reviews.

it brought in over $105 million over the weekend, the highest weekend tally ever for a live action comedy. another break. when we come back, a big favorite of ours, and we hope yours as well. every year at this time, the send-off for the class of 2011.

as we mentioned before the break, the time has come tonight to continue our annual tradition around here, showing you the best of this year's college commencements and meeting members of the graduating class along the way. there's no shortage of advice for them. but among them there's no shortage of brains or talent or spirit, either. so here now, your class of 2011. ♪ >> i think it's incredible that four years have gone by in the blink of an eye. >> i have very persnickety hair. >> the jig is up. the clock has run out. and the future with a capital f now rests with all of you and your goofy hats.

>> the plot you choose may change or even elude you. but being your own story means you can control the theme. >> i'm matthew randall. >> i'm someone who's definitely very silly. >> i'm michael wynn. i'm very personable. >> i'm a student veteran. >> let's think about those who would love to be sitting in the chairs you occupy today. the entire time you've been here at fordham there have been young men and women in uniform over there serving in two wars. >> my time in iraq is really, really hard to put to words. >> you were young children when you watched planes hit the world trade center world trade center.

you quickly understood what it was like to feel out of control. >> i was in seventh grade. from the window we could see the smoke coming from the towers. >> the shooting brought to my front yard things that i thought i had put away a long time ago. this is a beloved member of this community. >> the country's most powerful earthquake -- >> the massive earthquake and tsunami hit my home town, sendai city, japan. everything was gone. >> i looked out, and i couldn't see the end of the tornado to left or right. it's an awe-inspiring terror. >> i can report to the american people -- >> we ran down to the white house to celebrate that moment in history. [ cheers and applause ] >> do not let the many challenges of the world discourage you. don't let the cynics and

skeptics dampen your enthusiasm. dream, my friends. dream. ♪ you fall up >> i dream to be a film director and producer. >> well, i have lots of dreams. i dream of saving the world. >> what brought down hosni mubarak was not facebook, and it was not twitter. it was a million people in the streets ready to die for what they believed in. so if you want to get something done in the world, never forget, ultimately you have to get out of facebook and into somebody's face. >> and every single day i walk into the oval office and for all the days of my life i will always remember that in no other nation on earth could my story be possible. could your stories be possible.

>> we are some of the most resilient -- >> determined. >> compassionate. >> we are unwilling to carry on the hatred. ♪ >> i really love you. >> so there you have it. humility, patience, and faith. and always a few tears from me. >> i'm the class. >> of 2011. >> [ speaking foreign language ]. >> [ speaking foreign language ]. >> now go get 'em. what you just saw is an annual labor of love. it represents months of work by our crack team of producer victor limhoko and our terrific editor bev chase, even desk assistant shay connelly. and if you want to hear more from those great students we profiled there, there's a terrific interactive feature on our website for that at nightly.msnbc.com. and before we forget, congratulations to the class of

2011. that's our broadcast for this tuesday night. thank you for being here with us. i'm brian williams. we hope to see you right back here tomorrow evening. we hope to see you right back here tomorrow evening. good night. -- captions by vitac -- www.vitac.com good evening, everyone, i'm jessica aguirre. >> and i'm raj mathai. we begin with developing news tonight and it's good news. the frantic search for a missing 1-month-old baby girl is over. was it a planned child abduction or a car theft gone wrong? either way, the baby is back with her mother. we bring