What is the evidence that personal hair dye use is associated with risk of NHL?
A number of studies have investigated the relationship between the personal use of hair dyes and the risk of NHL, with inconsistent results. Because the small size of some studies may have limited their ability to detect associations, a pooled (combined) analysis of four case-control studies was carried out (6). All four studies had obtained detailed information on hair dye use, including dates and duration of use, and on NHL subtype. The pooled analysis included 4,461 women with NHL and 5,799 women who did not have NHL. The results of the study showed that women who began using hair dye before 1980 had a slightly (30 percent) increased risk of NHL compared with women who had never used hair dye, whereas no such increase in risk was seen for women who began using hair dye after 1980. When the researchers analyzed the risks of several specific NHL subtypes, they found that hair dye users had increased risks of both follicular lymphoma and chronic lymphocytic leukemia/small lymphocytic l
