Actor Mark Ruffalo has reportedly been placed on a US terror advisory list after campaigning in support of a documentary highlighting the alleged dangers of natural gas drilling.

Ruffalo attracted the attention of Pennsylvania's Office of Homeland Security when he organised screenings for Gasland, which won the special jury prize at this year's Sundance film festival, and said he was concerned about the impact of drilling on water supplies. The actor has addressed the subject in the latest edition of American GQ.

Gasland, directed by Josh Fox, follows the film-maker as he visits communities in Pennsylvania where natural gas has been drilled. Fox decided to document his trip after a natural gas company wrote to him in 2008 offering to lease his family's land in Milanville, Pennsylvania for $100,000 (£64,000).

The documentary attracted attention for a particular scene in which a local man shows that he is able to set his tapwater on fire (see 2.25 of video, above). Others claim they are suffering from numerous health issues due – they believe – to their water having been contaminated.

Gasland has been fiercely opposed by the natural gas industry. A pro-oil and gas organisation, Energy in Depth, has published a list of claimed factual inaccuracies in the documentary.