Some Women at Higher Risk
The cancer-causing chemicals linked to hair dye are members of a class of chemicals known as aromatic amines. The human body is able to detoxify these compounds. But because of their genetic makeup, some people can't detoxify the compounds. Those people, Yu last year reported in the journal Carcinogenesis, are the ones most at risk from hair dyes.
Zheng, too, is looking for genetic factors that increase a hair-dye user's risk of non-Hodgkin's lymphoma.
But Yu warns that this doesn't mean hair dyes don't pose a general risk.
"I would be hesitant to put women into two baskets -- so many genes are involved," Yu says. "I would say our study suggests the risks are stronger [for women lacking working detox genes], but I wouldn't say women who think they are not deficient could just assume that they are not at risk."