Early hair dyes contained a number of chemicals which were carcinogens. In 1970s, however, a number of these substances were removed from dyes. Unfortunately, many women and some men had already been exposed to these products on a regular basis for many years either as consumers or as hair dressers.
Now, a study (of women) conducted by researchers from the International Agency for Research on Cancer (France) indicates that those who regularly used hair dye (before 1980) had a 20% greater risk of developing lymphoma than women who had never dyed their hair before 1980. It is estimated that about 33% of women and 10% of men over 40 now use hair dye. There is no increased risk, however, associated with hair dyes used in the past 25 years.
Lymphomas are cancers of the lymphatic system which, in most cases, produce abnormal lumps on the body. The researchers suggest that anyone who was exposed to hair dyes on a regular basis before 1980 should be aware of the risk and self-examine themselves for any unusual or abnormal lumps.