Medical News Today, David McNamee, June 10, 2014
The following is an article (“Is hair dye to blame for hairdressers’ increased risk of bladder cancer?”) that was published in Medical News Today.
1. A new study in Occupational & Environmental Medicine has
2. linked frequency of dye and perm use to raised levels of carcinogens
3. found in hairdressers' blood.
4. Previous studies have found that hairdressers have an excess risk for
5. bladder cancer. Researchers believe this excess risk comes from
6. exposure to carcinogenic aromatic amines in some hair dyes, which
7. have also been linked to increased risk for non-Hodgkin lymphoma
8. and leukemia.
9. These carcinogens were present in 89% of commercial hair dyes during
10. the 1970s but were subsequently phased out as restrictions on hair dye
11. formulas were introduced.
12. However, studies in the US and Turkey screening for these banned
13. substances in commercial hair dye products still report levels of
14. carcinogenic aromatic amines.
15. In the new study, researchers from the Division of Occupational and
16. Environmental Medicine in Lund, Sweden, wanted to measure long-term
17. exposure to known and suspected carcinogenic aromatic amines
18. among hairdressers.
19. To do this, they assessed blood samples from 295 female hairdressers, 32
20. regular users of hair dyes and 60 people who had not used hair dyes in the
21. past year. The researchers also gathered data on the participants' other
22. jobs, hobbies and lifestyle that could have influenced the results.
23. The authors decided to use a much greater number of hairdressers than
24. other groups because they wanted to study dose-response associations,
25. which requires a large sample group.
26. Overall, levels of aromatic amines did not differ significantly between
27. the three groups. However, in the hairdressers, their weekly levels of
28. aromatic amines called o- and m-toluidines were shown to correspond
29. with the number of permanent light hair color treatments they applied to
30. clients. Toluidines are known to be carcinogenic.
31. Higher concentrations of o-toluidines were also associated with use of a
32. hair-waving product, a finding that the researchers describe as "somewhat
34. The researchers note the findings of a recent study that found o-toluidines
35. to be responsible for an increase in bladder cancer among workers at a
36. chemical manufacturing plant.
37. Given their study's findings, the authors suggest that ingredients of hair
38. dyes and perming products should be analyzed to see if these products
39. continue to expose the public to carcinogens.
40. A Turkish study that undertook a similar task analyzed 54 permanent hair
41. dyes and found that concentrations of o-toluidine could be up to 100 times
42. stronger in dark-yellow permanent hair dye and up to 500 times stronger in
43. black hair dyes.
44. "This indicates that there is a high variation between products and further
45. supports our ﬁndings that high o-toluidine adduct concentrations may
46. originate from speciﬁc products," write the authors behind the new study.
47. The researchers also recommend that hairdressers should minimize
48. exposure risk by wearing gloves and by doing any tasks that cannot be
49. performed wearing gloves - such as cutting hair - before any dyes or perms
50. are applied.
51. In 2011, Medical News Today reported on a study by researchers from the
52. National Allergy Research Centre at Copenhagen University in Denmark.
53. They found that people with allergies to substances such as hair dye and
54. latex rubber may have an immune system that can be triggered into
55. defending against some types of cancer.
Based on the passage, what caused hairdressers to be exposed to aromatic amines?