Bladder cancer among hairdressers: a meta-analysis.
BACKGROUND
Occupational risks for bladder cancer in hairdressers by using hair products have been examined in many epidemiological studies. But owing to small sample sizes of the studies and the resulting lack of statistical power, the results of these studies have been inconsistent and significant associations have rarely been found.


METHODS
We conducted a meta-analysis to determine summary risk ratios (SRRs) for the risk of bladder cancer among hairdressers. Studies were identified by a MEDLINE, EMBASE, CENTRAL search and by the reference lists of articles/relevant reviews. Statistical tests for publication bias and for heterogeneity as well as sensitivity analysis were applied. In addition, the study quality and the risk of bias were assessed using six criteria.


RESULTS
42 studies were included and statistically significantly increased risks around 1.3-1.7 were found for all but one analysis. The SRR increased with duration of employment from 1.30 (95% CI 1.15 to 1.48) for 'ever registered as hairdresser' to 1.70 (95% CI 1.01 to 2.88) for 'job held > or = 10 years'. No difference was found between the risk for smoking-adjusted data (SRR 1.35, 95% CI 1.13 to 1.61) and no adjustment (SRR 1.33, 95% CI 1.18 to 1.50). Studies assessed as being of high quality (n=11) and of moderate quality (n=31) showed similar SRRs. There was no evidence of publication bias or heterogeneity in all analyses.


CONCLUSIONS
In summary, our results showed an increased and statistically significant risk for bladder cancer among hairdressers, in particular for hairdressers in jobs held > or = 10 years. Residual confounding by smoking cannot be totally ruled out. Because of the long latency times of bladder cancer it remains an open question whether hairdressers working prior to 1980 and after 1980, when some aromatic amines were banned as hair dye ingredients, have the same risk for bladder cancer.
Harling
Melanie
M
Institution for Statutory Accident Insurance and Prevention in the Health and Welfare Services, Department of Occupational Health Research, Pappelallee 35/37, Hamburg 22089, Germany. melanie.harling@bgw-online.de
Schablon
Anja
A
Schedlbauer
Grita
G
Dulon
Madeleine
M
Nienhaus
Albert
A
D000588:Amines / Q000633:toxicity*; D005260:Female; D006202:Hair Dyes / Q000633:toxicity*; D006801:Humans; D015994:Incidence; D008297:Male; D016273:Occupational Exposure / Q000009:adverse effects*; D012307:Risk Factors; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced / Q000453:epidemiology*
D000588:Amines; D006202:Hair Dyes
J Epidemiol Community Health. 1998 Jun;52(6):377-84
9764259
Am J Epidemiol. 1994 Dec 15;140(12):1061-80
7998589
J Natl Cancer Inst. 1984 May;72(5):973-81
6585596
Am J Ind Med. 1990;17(2):217-23
2301410
BMJ. 1997 Sep 13;315(7109):629-34
9310563
Br J Urol. 1998 Jul;82(1):25-32
9698659
Urol Clin North Am. 1984 Nov;11(4):557-66
6506370
Br J Ind Med. 1988 Jun;45(6):361-7
3395572
J Natl Cancer Inst. 1989 Oct 4;81(19):1472-80
2778834
J Toxicol Environ Health A. 2008;71(13-14):906-10
18569594
Int J Cancer. 1990 Jun 15;45(6):1012-7
1693598
Int J Cancer. 2003 May 20;105(1):108-12
12672039
J Occup Environ Med. 2001 Mar;43(3):250-8
11285873
Scand J Urol Nephrol Suppl. 2008 Sep;(218):64-78
18815919
J Occup Environ Med. 2002 Jul;44(7):685-91
12134533
Occup Environ Med. 1997 Jun;54(6):443-51
9245952
Eur J Cancer Prev. 1995 Feb;4(1):31-43
7728096
Occup Environ Med. 2008 May;65(5):347-53
17951336
Scand J Work Environ Health. 1982;8 Suppl 1:79-82
7100861
J Toxicol Environ Health A. 2008;71(13-14):851-5
18569584
Cancer Causes Control. 2004 Oct;15(8):759-69
15456989
Int J Cancer. 1985 May 15;35(5):599-606
3997281
Cancer Causes Control. 1991 Nov;2(6):371-9
1764561
Contemp Clin Trials. 2007 Feb;28(2):105-14
16807131
Am J Ind Med. 1994 May;25(5):677-88
8030638
Versicherungsmedizin. 1994 Oct 1;46(5):158-61
7974986
ANZ J Surg. 2003 Sep;73(9):712-6
12956787
Int Arch Occup Environ Health. 1992;64(1):39-42
1399013
Int J Epidemiol. 1986 Dec;15(4):456-62
3818152
Am J Epidemiol. 1990 Sep;132(3):453-61
2389750
Cancer Causes Control. 2004 Dec;15(10):1007-19
15801485
J Epidemiol Community Health. 1980 Sep;34(3):182-5
7441138
Cancer. 1992 Apr 1;69(7):1776-90
1551063
Chem Res Toxicol. 2003 Sep;16(9):1162-73
12971805
Int J Cancer. 2001 Feb 15;91(4):575-9
11251984
Br J Cancer. 2005 Apr 11;92(7):1276-8
15770207
Int J Cancer. 2008 Mar 15;122(6):1340-6
18027852
Crit Rev Toxicol. 2007;37(6):521-36
17661215
Cancer. 1972 May;29(5):1250-60
5021618
Proc Natl Acad Sci U S A. 1975 Jun;72(6):2423-7
1094469
Int J Epidemiol. 1985 Dec;14(4):549-54
4086141
J Occup Med. 1976 Dec;18(12):787-92
993872
Int J Epidemiol. 1988 Sep;17(3):493-500
3209325
Evid Rep Technol Assess (Summ). 2002 Mar;(47):1-11
11979732
Dtsch Med Wochenschr. 2007 Jan 26;132(4):133-4
17230326
Skin Pharmacol. 1994;7(1-2):94-100
8003332
Int J Epidemiol. 1993 Jun;22(3):403-11
8359955
Am J Ind Med. 1989;16(1):89-102
2750753
J Natl Cancer Inst. 1980 Apr;64(4):701-13
6928984
J Natl Cancer Inst. 1984 May;72(5):1051-7
6585583
PLoS Med. 2007 Oct 16;4(10):e297
17941715
Scand J Work Environ Health. 2002;28 Suppl 1:1-88
11871426
Am J Ind Med. 1984;6(3):207-30
6475966