The blockbuster movie "Avatar" makes some enthusiasts depressed and gives others headaches.

To America's legions of feisty conservatives, its tale of money-grabbing Americans who exploit native people - albeit on another planet - is another example of leftwing Hollywood elitism. Yet, some progressives blast the movie as racist.

It also riles the anti-smoking lobby, and if that wasn't enough, some critics charge that the story was stolen from Russian sci-fi novels.

Despite - or perhaps because of - that heap of controversy, "Avatar" is within striking distance of becoming the highest grossing film of all time.

As it continues to reign supreme above the worldwide box office, it is the first movie ever to have a realistic chance of beating the $1.8 billion earned by "Titanic", director James Cameron's previous film in 1997.

Like "Avatar", "Titanic" was also blasted for its bloated budget, wooden dialogue and predictable plot. But it never amassed the broad range of ideological critics that have attacked Cameron's latest sci-fi blockbuster.

The most recent broadside launched at "Avatar" came from America's powerful anti-smoking lobby. Their ire was directed at the character played by Sigourney Weaver, who in the film is still puffing away on her cigarettes some 150 years in the future.

The group, called Smoke Free Movies, took out full page ads in trade papers Variety and The Hollywood Reporter to protest the on-screen smoking. It argued that for every $100 million the movie earns at the box office, it will "deliver an estimated 40 million tobacco impressions to theatre audiences". The organisation estimated that this represented some $50 million worth of free advertising for the tobacco industry.

"Avatar" director James Cameron said he agreed that role models for young people should not smoke in films, but that "movies should reflect reality".

But there was no easy answer to complaints from some viewers that the new 3-D viewing system gave them splitting headaches.

According to Michael Rosenberg, an ophthalmology professor at Northwestern University's Feinberg School of Medicine in Chicago, the innovative system exacerbates minor eye problems.

"That translates into greater mental effort, making it easier to get a headache, " he said in an online post.

But dull pain in the brain is not the only health risk being posed by the hit movie.

Diehard fans, now widely known as Avatards, are filling online forums with their complaints about how the film is making them depressed as they realise their own lives can never hope to match the primitive beauty found on the Pandoran planet. One popular forum about how to deal with the post-"Avatar" blues has already registered more than 1, 000 threads.

Other people are leaving the movie feeling angry. Hollywood has long been regarded as a fifth column by US conservatives, but the tale of US Marines out to ruthlessly exploit the noble savages of Pandora has raised a new level of ire.

"This is the only time I ever sat in a theatre where people were cheering the forest and the blue people, attacking ex- Marines, " said conservative activist Tom Roeser. "That's the Hollywood view of us. We are the exploiters. We are pre- emptive attackers."

Meanwhile, some on the left wing are incensed at the movie, charging that its storyline of a white ex-marine riding to the rescue of a primitive people is inherently racist.

New York Times columnist David Brooks called it a "racial fantasy par excellence", arguing that the movie "rests on the assumption that non-whites need the White Messiah to lead their crusades". "It also creates a sort of two-edged cultural imperialism, " he said. "Natives can either have their history shaped by cruel imperialists or benevolent ones, but either way, they are going to be supporting actors in our journey to self-admiration."