How to confront new office mate regarding personal hygiene? I am a senior graduate student and share an office with 3 other post-docs and graduate students.  We recently had a first year graduate student join our lab for a rotation and he has been placed in our office.  This new student has intense body odor, to the point where you can smell it in the hallway outside our office when the door is open.  I have asked my other office mates what to do about it and their responses have ranged from "I don't notice it" to "Yeah it's bad but there's nothing we can do about it/I'm not saying anything".

To me, there is no way one can't notice  I have found it distracts me from my work.  I imagine my advisor has noticed, but so far no one has mentioned anything and I have been the only one to bring it up with anyone else.  I've asked friends who work in industry what they'd do, and they say "don't say anything but immediately report it to HR", which doesn't particularly help in my situation.

As the semester is coming to a close, it's only getting hotter outside and the rotating student will be present more often in the lab.  I'm afraid to say anything because 


I don't want to make things uncomfortable, especially since we need to train him; 
I'm afraid I'm being culturally insensitive as he is a foreign student.
He may have a medical, religious, or other reason that leads to the smell, and I don't want to offend.


Because this is an academic lab, I have no access to an HR department.  Any advice?  

A related question (which was not closed) can be found here.  In this question, and those found on The Workplace SE, most answers are "tell him privately and nicely", but I'm worried about being insensitive because he is new, I haven't gotten to know him personally, and he may have cultural, religious, or other reasons for not wearing deodorant.
After some clarifications via comments above: 

There is surely an office with a name something like "Student Services" that would be the front end for many issues involving conflicts/issues between students or conflicts/issues between students and faculty. It is not possible to guess the name of the corresponding office at your university, so some experimentation or asking around is necessary. You should definitely consult with them about what actions on your part would be approved or disapproved.

There surely is an HR office at your university (assuming it's in the U.S.), which has some oversight powers/responsibilities for any paid personnel. Probably most grad students have not had any interactions with that office, but it surely exists, and does some back-end checking of hiring and such.

Many years ago, as director of graduate studies in mathematics at a U.S. "R1" university, I found myself the recipient of complaints from office-mates about the hygiene of a grad student. Having been already sensitized to the volatility of such issues, I wrote a somewhat vague, but pointed, message to all grad students in the math dept about "expectations" for hygiene, given their TA duties. Naturally, most were confused as to why I was writing this at all, but the "broadcast" aspect did avoid confrontation with individuals. Also, there was certainly the aspect that there was a job getting done for pay, and interference, accidental or not, was not ok. If the person had not been paid by our department, I would have been much more inhibited about strongly-recommending hygiene modifications, just given the way things seem to work here.