Sean Penn: 'Human Experiment' Documentary Trailer!

Sean Penn shows off his bulging biceps in a tight black t-shirt while leaving his hotel on Tuesday morning (September 3) in London, England.

The 53-year-old actor was seen wheeling his luggage while making his way through Heathrow Airport over the weekend.

Sean is the executive producer and narrator of the new documentary The Human Experiment and now the first trailer for the film has arrived.

PHOTOS: Check out the latest pics of Sean Penn

The documentary “follows a band of unlikely activists in order to investigate the personal costs associated with the chemicals in common household products,” according to The Hollywood Reporter. The film will have its world premiere at the Mill Valley Festival in October.

10+ pictures inside of Sean Penn out and about in London…