Hair Dye May Cause Bladder Cancer
Study Finds Genetic Makeup Could Be Factor
POSTED: 12:08 p.m. EDT April 11, 2002
Some women may be more susceptible to bladder cancer because of their use of permanent hair dyes than other women, based on their genetic makeup, according to a study released by researchers at the Keck School of Medicine at the University of Southern California.
Female study participants whose bodies could only slowly flush out carcinogens known as arylamines, which are an ingredient of hair dye, had a higher risk of bladder cancer than women whose bodies eliminated the carcinogens more quickly, the investigators reported.
The body's efficiency in removing such toxins depends on whether someone possesses the "fast" or "slow" version of certain key genes.
"We believe these results provide further evidence supporting a causal association between permanent hair dye use and bladder cancer risk," said Dr. Manuela Gago-Dominguez of the University of Southern California, lead author of the study.
Early in 2001, USC researchers reported that women who use permanent dyes at least once a month for one year or longer have twice the risk of bladder cancer as non-users. Monthly or more frequent users of 15 or more years experience three times that risk even after adjusting for smoking, a known risk factor for bladder cancer.
The increase in bladder cancer risk also was observed in people who are exposed to hair dyes in their work, such as barbers and hairdressers. Increased risk was not seen for those who used temporary or semi-permanent dyes.
Gago-Dominguez explained that small amounts of arylamines are absorbed through the skin during the use of hair dye. Certain agents contained in permanent dye might cause more of the arylamines to be absorbed through the skin than in the case of temporary or semi-permanent dyes, some theorize.
Certain important, protective enzymes in the body metabolize those arylamines, trying to render them harmless. The body expels the chemicals through urine, which passes through the bladder. The efficiency of these protective enzymes depends on genes that provide the recipe for making the enzymes.
The research team looked at 159 female bladder cancer patients in Los Angeles and compared them to 164 similar, healthy women, analyzing their genetic makeup through blood and urine samples. They found that in women with certain slow genes, exclusive permanent hair dye use was associated with a nearly tripled risk of bladder cancer.
Among women with other slow genes, exclusive permanent hair dye use was associated with a 2.5-fold increased risk. Finally, among non-smoking women with a third type of slow genes, exclusive permanent hair dye use was associated with a 6.8-fold increased risk.
Further study is needed to fully understand relationships between hair dyes and bladder cancer, researchers said.
Female study participants whose bodies could only slowly flush out carcinogens known as arylamines, which are an ingredient of hair dye, had a higher risk of bladder cancer than women whose bodies eliminated the carcinogens more quickly, the investigators reported.
The body's efficiency in removing such toxins depends on whether someone possesses the "fast" or "slow" version of certain key genes.
"We believe these results provide further evidence supporting a causal association between permanent hair dye use and bladder cancer risk," said Dr. Manuela Gago-Dominguez of the University of Southern California, lead author of the study.
Early in 2001, USC researchers reported that women who use permanent dyes at least once a month for one year or longer have twice the risk of bladder cancer as non-users. Monthly or more frequent users of 15 or more years experience three times that risk even after adjusting for smoking, a known risk factor for bladder cancer.
The increase in bladder cancer risk also was observed in people who are exposed to hair dyes in their work, such as barbers and hairdressers. Increased risk was not seen for those who used temporary or semi-permanent dyes.
Gago-Dominguez explained that small amounts of arylamines are absorbed through the skin during the use of hair dye. Certain agents contained in permanent dye might cause more of the arylamines to be absorbed through the skin than in the case of temporary or semi-permanent dyes, some theorize.
Certain important, protective enzymes in the body metabolize those arylamines, trying to render them harmless. The body expels the chemicals through urine, which passes through the bladder. The efficiency of these protective enzymes depends on genes that provide the recipe for making the enzymes.
The research team looked at 159 female bladder cancer patients in Los Angeles and compared them to 164 similar, healthy women, analyzing their genetic makeup through blood and urine samples. They found that in women with certain slow genes, exclusive permanent hair dye use was associated with a nearly tripled risk of bladder cancer.
Among women with other slow genes, exclusive permanent hair dye use was associated with a 2.5-fold increased risk. Finally, among non-smoking women with a third type of slow genes, exclusive permanent hair dye use was associated with a 6.8-fold increased risk.
Further study is needed to fully understand relationships between hair dyes and bladder cancer, researchers said.
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