From the time she was a small child until she was a teenager, Annmarie Spellen chemically straightened her hair — a process that left her nursing burns and scabs on her scalp afterwords.

The hospital worker, 37 and mother of two from Hackensack, NJ said she got burned “all the time” despite using no lye relaxers and having the stylist wash the relaxer out immediately after putting it in.

“I did it for as long as I could,” said Spellen, who has worn her hair in dreadlocks for the past ten years. “I tried, and I just couldn’t do it. It was just too devastating. It was like going through a trauma.”

But the scalp burns weren’t the only health problem she experienced following a chemical relaxer.

“I would go home with these massive headaches,” Spellen said. “And I couldn’t understand why.”

Black women spend billions annually on beauty products, and many place special emphasis on keeping their hair styled. They buy a third of all U.S. hair care merchandise, according to industry statistics. The black hair care business has ballooned into a $9 billion a year industry.

But scientists and environmental justice advocates said the number of potentially dangerous chemicals used as ingredients in some hair care products can jeopardize women’s health — that the chemical relaxers, oil sheen, hair grease, and spray women apply to her hair and scalp could be laced with harmful chemicals.

Lye, phthalates, placenta and parabens are among the hazardous chemicals found in a multitude of hair care products marketed toward African-American women. Lye, or sodium hydroxide, can cause chemical burns, scars and blindness. Phthalates, sometimes listed simply as “fragrance” on product ingredient lists, is also linked to endometriosis, or when uterine lining grows outside the uterus. Phthalates, parabens and animal placenta can mimic hormones and disrupt critical processes in the body, scientists have said.

“African-American women, compared to their white counterparts, have higher levels of phthalates and they have higher levels of BPA,” said Dr. Ami Zota, an environmental health researcher at the University of California San Francisco. BPA is used in plastic manufacturing and has been linked to cancer and reproductive abnormalities. “Nobody has really figured out why,” Dr. Zota said. “But I think the hair care products are part of that story.”

The hormone disruptors in beauty products may have already had an effect on a generation of young girls. The onset of puberty for all girls in the U.S. has gradually increased by a few months since the 1950s, while breast development has accelerated by up to two years, according to a 2009 report from the Collaborative on Health and the Environment.Black girls ages 1-through-8 who used hair products containing placenta for as little as two months developed breasts and pubic hair, a 1998 study published in Clinical Pediatrics found. When they stopped using the products, their early sexual development did too.

An August 2010 study found that almost a quarter of African-American girls and 15 percent of their Latina peers had some stage of breast development by age 8. Some scientists have attributed the earlier onset of puberty to being exposed to chemicals that mimic hormones, along with increased body weight, diets high in fat and sugar and decreased physical activity.

“Lifetime exposure to estrogen increases your risk of breast cancer,” Dr. Zota said. “If you’re getting your menstruation earlier, that’s increasing the natural estrogen that you’re exposed to.”

Cancer rates among African-American pre-menopausal women are higher than their white peers. In fact, a 2008 study published in the Journal of the National Cancer Institute found that black women under age 30 had a 52 percent higher incidence rate of developing breast cancer than white women.

The U.S. Food and Drug Administration does not currently test the majority of health and beauty products before they go on sale. One way consumers can get safer products on shop shelves is by asking their salon or manufacturers to make alternatives available, Dr. Zota said.

Congress is mulling a bill, the Safe Cosmetics Act, which would ban dangerous chemicals in salon products and require safety checks before a product is sold in stores.

Cherisse Scott, a health educator for Black Women for Reproductive Justice, a Chicago non-profit that works on reproductive health advocacy issues, said some black women may feel cultural or societal pressure to straighten their hair, unwittingly exposing themselves to dangerous chemicals in the process.

“It’s a deep-seeded problem,” Scott said. “It’s hard when you’re in a society that requires you to look a certain way.”

In addition to safer products, Scott called for a more open and honest dialogue in the black community about its’ sometimes unhealthy relationship with hair.

“Environmental justice for us,” she said, “means tackling some of these deep-seeded generational issues also.”