Holi, which many Indians in the Hindu-majority nation celebrate with gusto, sees people of all faiths trying to blur inhibitions in a haze of color to welcome the new season.

But the festival's growing popularity has drawn concern from police and doctors, who are urging more caution.

"Don't let Holi lose all its colors," warned a police advert in newspapers this week, vowing a crackdown on drunken behavior and harassment of women.

But also cautioning the public were dermatologists, who said the cheap chemical-based powder colors that contributed to the vibrancy and fun quotient of the festival were a major health hazard.

"One should particularly stay away from silver and red colors, because they are more toxic" than others, warned R.K. Joshi, a dermatologist at New Delhi's Apollo Hospital.

"These colors are metallic oxides, some also contain industrial dyes. These are carcinogenic. They could enter the body through the nails, mouth and even nostrils" and cause a range of health problems, he said.

"These colors are harmful for the eyes and hair too."

A New Delhi-based environmental group, Toxics Link, which conducted a study on the harmful effects of chemical powder colors, said many contained mica, acids, alkalis and even coarsely ground glass.

"Some of these impair vision and cause respiratory problems," said a press release issued by the group.

Metals like lead, chromium, cadmium and nickel caused learning disabilities, bronchial asthma, dermatitis and pneumonia, it added.

According to Manisha Gutman, an activist campaigning for the use of organic or plant-based powder colors, people were gradually becoming aware of the dangers of using chemical powders and were "turning to these naturally made products."

"We started this campaign to sensitize people about the benefits of organic colors five years ago, and the response is good," said Gutman, who heads Ecoexist, a firm based in the western city of Pune.

"The colors we make use turmeric as a base so it has no harmful effects. We have enlisted the help of some women farmers in Karnataka who grow the spice that we use for colors every year," she told Agence France-Presse by phone.

Madhumita Puri, another activist promoting organic colors, said the campaign neatly dovetailed with other objectives such as keeping rivers clean and protecting the environment.

"The organic colors we make use flowers discarded from temples as their core ingredient," she said, referring to floral offerings made by the devout in countless temples across India.

"Ordinarily, these flowers would be flung into rivers like the Yamuna, choking the flow of water. But we collect these discarded flowers, dry them and use them to make the colors," the Delhi-based Puri explained.

Both Puri and Gutman said some steps in the manufacturing process of organic colors were outsourced to help the disadvantaged.

"This year, the packaging of organic colors was done by women prisoners" in the Pune jail, said Gutman.

He said the only factor slowing the popularity of organic colors was the relatively high cost.

"At 200 rupees (US$4) a kilogram, it is still a rich person's product," he said.

"The man on the street can't afford it yet so the huge market for cheap chemical colors will thrive for a while yet."