ABSTRACT
QUESTION Several of my pregnant patients who are hairdressers have asked me if exposure to products they use is harmful to their unborn babies. They also want to know if their pregnant clients’ personal use of hair products should be of concern.
ANSWER There is no evidence of teratogenic effects for pregnant women exposed to these products from occupational use (ie, hairdressing); however, it is recommended that pregnant hairdressers wear gloves to minimize exposure, work for no more than 35 hours per week, avoid standing for prolonged periods of time, and ensure that the salons where they work have adequate ventilation. Evidence suggests there is minimal systemic absorption of hair products, so personal use by pregnant women 3 to 4 times throughout pregnancy is not considered to be of concern.
Chemicals in hair products colour, straighten, relax, curl, and bleach hair. Hair dyes are often divided into 5 categories: gradual hair colouring, vegetable dyes, temporary dyes, semipermanent dyes, and permanent dyes.1 The most common chemicals used in permanent hair colours are phenylenediamine, 3-aminophenol, resorcinol, toluene-2,5-diaminesulphate, sodium sulfite, oleic acid, sodium hydroxide, ammonium hydroxide, propylene glycol, and isopropyl alcohol.2 The chemicals used in hair straighteners or relaxers, bleachers, and permanents include sodium hydroxide, guanidine hydroxide, ammonium thioglycolate, ammonium hydroxide, petroleum, and hydrogen peroxide.3,4
Harmful effects
Some of the chemicals used in hair products have been reported to be carcinogenic5; however, many of these chemicals have been eliminated from oxidative dye products since the early 1980s. There have been reports of hair products being associated with bladder cancer, non-Hodgkin lymphoma, multiple myeloma, acute leukemia, and neuroblastoma in offspring. However, these results have been inconsistent; most studies conducted on personal or occupational use of hair dyes showed no increased risk of cancer.6–9
Exposure during pregnancy
Experimental animal studies showed risks of teratogenicity due to some of the chemicals found in hair products, namely phenylenediamine,10 aminophenols,11–12 and ethanolamine,13 when used in very high doses. Human studies, however, show that exposure to these chemicals from hair dyes or hair products results in very limited systemic absorption, unless there are burns or abscesses on the scalp. Therefore, these chemicals are unlikely to reach the placenta in substantial amounts to cause harm to the unborn fetus.14–18
Occupational exposure
As hairdressers are exposed to chemicals that have been suggested to be teratogenic, embryotoxic, and carcinogenic, Labrèche et al attempted to measure the chemicals in the air at a number of hair salons. All chemicals measured were well below the threshold limits recommended by the American Conference of Governmental Industrial Hygienists.19 Hueber-Becker et al found that plasma levels of an oxidative hair dye were below the limit of detection in 18 hairstylists who each performed 6 hair-colour jobs in 1 day.20
A study by John et al, who examined the working conditions of pregnant women in beauty salons, found that the risk of spontaneous abortions did not increase with the number of hair-dye jobs performed per week.21
Zhu et al compared 550 hairdressers with a nonexposed group and found no statistically significant differences in fetal loss, preterm birth, small for gestational age babies, congenital malformations, or achievement of developmental milestones among their children.22 A Swedish study also did not find an increased rate of birth malformations among offspring of hairdressers when compared with those of a nonexposed group.23 In a later study, the same group found neither an increased risk of spontaneous abortion nor fertility concerns among hairdressers.24
Personal exposure
A case-control study by Blackmore-Prince et al found no increased risk for preterm delivery or low birth weight in 525 pregnant black women exposed to chemicals used to straighten and curl hair.4 Another case-control study by Rosenberg et al also did not find an association with preterm deliveries and use of hair relaxers during pregnancy in 5944 black women.25
There are no studies on occasional use of hair products during pregnancy. However, we have calculated that using these products 3 to 4 times during pregnancy would not be a concern, as they have minimal systemic absorption and women are exposed to them every 6 to 8 weeks at most during pregnancy.
Conclusion
In view of these data, use of hair products is unlikely to cause adverse fetal effects. With occupational exposure of hairdressers, the evidence suggests minimal systemic exposure to hair products; however, it is recommended that hairdressers wear gloves to minimize exposure, work for less than 35 hours per week, and avoid standing for prolonged periods of time. For the average pregnant woman, receiving hair treatments 3 to 4 times during pregnancy does not appear to increase risk of adverse effects on the fetus.
MOTHERISK
Motherisk questions are prepared by the Motherisk Team at the Hospital for Sick Children in Toronto, Ont. Dr Chua-Gocheco and Ms Bozzo are members and Ms Einarson is Assistant Director of the Motherisk Program.
Do you have questions about the effects of drugs, chemicals, radiation, or infections in women who are pregnant or breastfeeding? We invite you to submit them to the Motherisk Program by fax at 416 813-7562; they will be addressed in future Motherisk Updates.
Published Motherisk Updates are available on the College of Family Physicians of Canada website (www.cfpc.ca;) and also on the Motherisk website (www.motherisk.org;).
Footnotes
Competing interests
None declared
- Copyright© the College of Family Physicians of Canada
References
- ↵
BolducCShapiroJHair care products: waving, straightening, conditioning, and coloringClin Dermatol20011944316
OpenUrlPubMed
See AlsoIs it safe to use relaxers or straighten my hair during pregnancy?Hair Care During Pregnancy: Safety Dos and Don’tsThe Straight Truth About Using Relaxers While Pregnant and 5 Must-Have Products for Natural Hair CareWhich beauty and wellbeing treatments are safe during pregnancy and breastfeeding? | NCT - ↵
Van der WalleHBKanervaLElsnerPWahlbergJEMaibachHIHairdressersHandbook of occupational dermatologyNew York, NYSpringer2000
- ↵
WickettRRPermanent waving and straightening of the hairCutis19873964967
OpenUrlPubMed
- ↵
Blackmore-PrinceCHarlowSDGargiulloPLeeMASavitzDAChemical hair treatments and adverse pregnancy outcome among black women in central North CarolinaAm J Epidemiol199914987126
OpenUrlAbstract/FREE Full Text
- ↵
AmesBNKammenHOYamasakiEHair dyes are mutagenic: identification of a variety of mutagenic ingredientsProc Natl Acad Sci U S A197572624237
OpenUrlAbstract/FREE Full Text
- ↵
TakkoucheBEtminanMMontes-MartínezAPersonal use of hair dyes and risk of cancer: a meta-analysisJAMA200529320251625
OpenUrlCrossRefPubMed
RosenbergLBoggsDAAdams-CampbellLLPalmerJRHair relaxers not associated with breast cancer risk: evidence from the black women’s health studyCancer Epidemiol Biomarkers Prev200716510357
OpenUrlAbstract/FREE Full Text
KelshMAAlexanderDDKalesRMBufflerPAPersonal use of hair dyes and risk of bladder cancer: a meta-analysis of epidemiologic dataCancer Causes Control200819654958Epub 2008 Feb 20
OpenUrlCrossRefPubMed
- ↵
ZhangYSanjoseSDBracciPMMortonLMWangRBrennanPPersonal use of hair dye and the risk of certain subtypes of non-Hodgkin lymphomaAm J Epidemiol200816711132131Epub 2008 Apr 11
OpenUrlAbstract/FREE Full Text
- ↵
HrubyEPaarRLipplKSchwarzingerBHoferHTeratologic studies with m-phenylenediamine on ratsOesterr Forschungszent Seibersdorf19814132136
- ↵
ElderRLFinal report on the safety assessment of p-aminophenol, m-aminophenol, and o-aminophenolInt J Toxicol19887327933310.3109/10915818809023134
OpenUrlAbstract/FREE Full Text
- ↵
SpenglerJOsterburgIKorteRTeratogenic evaluation of p-toluenediamine sulfate, resorcinol, and p-aminophenol in rats and rabbitsTeratology198633231A
OpenUrl
- ↵
MankesRFStudies on the embryopathic effects of ethanolamine in Long-Evans rats: preferential embryopathy in pups contiguous with male siblings in uteroTeratog Carcinog Mutagen19866540317
OpenUrlPubMed
- ↵
LademannJRichterHJacobiUPatzeltAHueber-BeckerFRibaudCHuman percutaneous absorption of a direct hair dye comparing in vitro and in vivo results: implications for safety assessment and animal testingFood Chem Toxicol2008466221423Epub 2008 Feb 29
OpenUrlCrossRefPubMed
Cosmetic Ingredient Review Expert PanelFinal report on the safety assessment of HC Yellow No. 5Int J Toxicol200726Suppl 211324
OpenUrlAbstract/FREE Full Text
Cosmetic Ingredient Review Expert PanelFinal report on the safety assessment of Basic Blue 99Int J Toxicol200726Suppl 25163
OpenUrlAbstract/FREE Full Text
KraelingMEBronaughRLJungCTAbsorption of lawsone through human skinCutan Ocu Toxicol20072614556
OpenUrl
- ↵
CorbettJFMolaroRThe century of hair colourGlob Cos Ind2001169229
OpenUrl
- ↵
LabrècheFForestJTrottierMLalondeMSimardRCharacterization of chemical exposures in hairdressing salonsAppl Occup Environ Hyg20031812101421
OpenUrlCrossRefPubMed
- ↵
Hueber-BeckerFNohynekGJDufourEKMeulingWJde BieATToutainHOccupational exposure of haidressers to [14C]-para-phenylenediamine-containing oxidative hair dyes: a mass balance studyFood Chem Toxicol20074511609Epub 2006 Aug 30
OpenUrlCrossRefPubMed
- ↵
JohnEMSavitzDAShyCMSpontaneous abortions among cosmetologistsEpidemiology19945214755
OpenUrlCrossRefPubMed
- ↵
ZhuJLVestergaardMHjollundNHOlsenJPregnancy outcomes among female hairdressers who participated in the Danish National Birth CohortScand J Work Environ Health2006321616
OpenUrlPubMed
- ↵
RylanderLKällénBReproductive outcomes among hairdressersScand J Work Environ Health20053132127
OpenUrlPubMed
- ↵
AxmonARylanderLLillienbergLAlbinMHagmarLFertility among female hairdressersScand J Work Environ Health20063215160
OpenUrlPubMed
- ↵
RosenbergLWiseLAPalmerJRHair-relaxer use and risk of preterm birth among African-American womenEthn Dis200515476872
OpenUrlPubMed