“Every worker has the right to come home safely at the end of every day,” Dr. Michaels said. “They shouldn’t be coming home and getting sick.”

The debate over the chemicals has also unfolded at the state level. In 2005, lawmakers in California proposed banning DBP from cosmetic products sold or manufactured in the state. Industry lobbyists flooded the State Capitol (some bearing gift baskets of lipstick and nail polish), spending over a half-million dollars fighting the ban, according to state records. Some of the country’s best-known cosmetics companies — Estée Lauder, Mary Kay and OPI, among others — weighed in against it. The bill ultimately failed. A much more limited measure passed — over the industry’s objections — that required cosmetics companies to disclose certain hazardous chemicals to the California Department of Public Health.

Blocked by an industry with deep pockets, the California advocates say they had to scale back their goals. They introduced a grass-roots program that officially recognizes “healthy nail salons,” those that carry “greener” products and that ventilate. The New York City Council held a hearing this month on a measure that would establish a similar voluntary program.

Today, out of several thousand salons in California, however, there are just 55 salons in the program.

One of them is Lulu Nail Spa, a tiny salon with a dusky rose wall and white-leather pedicure chairs in Burlingame, Calif. The shop earned the designation in May by switching certain products, using gloves and opening the doors to sweep out fumes. The owner, Hai Thi Le, a Vietnamese immigrant, said she hoped the new decal she placed on her window would draw green-minded customers.

But she did not make the changes just for business. As a young woman working in her brother’s nail shop, Ms. Le said she breathed in so much acrylic powder that when she kissed her husband after work, he complained her breath smelled of solvent and plastic dust.

Standing in the Breeze

On her days off from the salon in Ridgewood, Queens, Nancy Otavalo ran for a time an ad hoc day care center at her home a few blocks away with her sister, another manicurist. The sisters would pick up salon workers’ children after school for a fee, entertaining them in the basement apartment the sisters shared with their families.