Good news for women who use hair dye - research indicates no link between dye use and cancer - Brief Article

Science News, Oct 22, 1994

For the past 2 decades, the worrisome question of a possible connection between hair-coloring products and cancer has lingered over the heads of dye users.

For example, mice treated with hair dye can develop tumors. And some human studies have reported a link between cancer and these coloring agents, especially darkcolored permanent dyes such as brown or black.

In February, researchers reported that women who had relied on black hair dye for 20 years or longer ran a slightly increased risk of dying from certain blood-based cancers, such as non-Hodgkin's lymphoma (SN: 2/5/94, p.86).

Now, epidemiologist Francine Grodstein and her colleagues at the Harvard School of Public Health in Boston have reexamined the question of hair dye and blood-based cancers. The Boston team focused on 99,067 registered nurses participating in the Nurses' Health Study.

The investigators asked the women about their current and past use of permanent hair dye. They also tracked cases of blood-based cancer among the nurses, from the study's start in 1976 until 1990.

The researchers sorted the women into two groups: hair-dye users and nonusers. Next, they looked at the number of women who developed certain blood-based cancers during the study period.

"There was no difference between the two groups," Grodstein says. The study, which appears in the Oct. 5 JOURNAL OF THE NATIONAL CANCER INSTITUTE, found no evidence of a link between the use of permanent hair dye and such cancers, including non-Hodgkin's lymphoma, Hodgkin's disease, multiple myeloma, and leukemia.

Still, the study suffers from some flaws. Among them: The researchers didn't ask the women specifically whether they used dark-colored hair dye.

To compensate, the team looked at hair dye use among women whose natural hair color was brown or black. Such women showed no increased cancer risk. (The researchers assume that women with naturally dark hair will rely on dark hair dye to color their gray.)

Despite this mostly good news, Grodstein and colleagues aren't ready to call a halt to the speculation regarding dark-colored hair dye. They suggest further studies must prove that long-term use of such coloring agents poses no cancer risk.