Those jeans you pull on before running out to the corner store were produced by one of the most toxic industries on the planet, according to a new documentary that explores how clothing manufacturers are poisoning the world's water supply.

The documentary "RiverBlue" highlights the environmental and human damage caused by the fashion industry, which uses highly toxic chemicals to produce 80 billion garments worldwide each year, while using 3.2 per cent of the world's fresh water. The film shines a particularly harsh spotlight on jean manufacturers, who dump large quantities of toxic waste into Asian waterways each year.

"RiverBlue" executive producer Roger Williams says he came upon the problem unexpectedly, while pursuing a more broad investigation into global water pollution.

"We came across a satellite photo from China, and it was just this big stain of blue coming down into the ocean," Williams told CTV's Your Morning on Tuesday. He says the "big stain" was toxic dye flowing out of Jingting, the so-called jean manufacturing capital of the world. "They're just letting the dyes run right into the rivers," he said.

Williams and his crew visited several countries for their documentary, including India, Spain, Indonesia, Bangladesh and China. He says, in some places, the rivers will run red, black or green, depending on the colour of the dyes being used in textile production. The smell of chemicals is also strong enough to trigger "instant headaches" in the more heavily-polluted areas, he says.

Lisa Mazzotta, who worked on the film as a producer, says environmental regulations are in place in many of these manufacturing areas, but they are simply not followed.

"It's really hard to make sure they're implemented," she told CTV's Your Morning. "The untreated waste is going into these rivers and there's little being done to stop it."

Williams says the waste pouring out of these manufacturing plants includes toxic chemicals and heavy metals like mercury, cadmium, lead and potassium, which kills wildlife and poisons humans.

Those who live near the manufacturing plants are said to inhabit so-called "cancer villages," where average life expectancy is significantly lower than other parts of those countries, Williams said. "It's devastating," he said.

Mazzotta hailed Greenpeace for its efforts to raise awareness about the issue, while Williams urged others to take up the cause themselves.

"There are new steps that can be implemented fairly easily, and we can actually reduce the chemical load," he said.

Mazzotta and Williams say buying second-hand clothing is an effective way to fight the problem at home. More tips are available on their website, Fashion Heroes.

"RiverBlue" will be showcased at the sixth annual Water Docs Film Festival, which runs from March 29-April 2 in Toronto.