Color me Safely: Pregnancy Hair Dyeing

Is there anything more satisfying when it comes to personal grooming than having a thick, shiny head. Are you able to divide your life into good and bad hair days? Do bad hair days make you feel depressed and lethargic, while good ones can propel you to the top. You are not alone! You’re not the only one!

According to Hoovers(r), there are approximately 65,000 hair salons in America with an annual combined sales of $19 billion. While a small percentage of these sales go towards hair cuts, the majority of these dollars are spent on hair color.

Please read carefully if you are pregnant, or planning to become pregnant, and if you work in one of these salons. Each year, hair dyes are used by over 20 million Americans, mainly women. Hair dyes are used by at least 35-40% of women in Europe and the United States. You can either get your hair done by a hairdresser in a salon or you can use over-the-counter products.

The International Agency for Research on Cancer, (IARC) says there are concerns about the safety of these products. Why? Some of the hair dye ingredients are carcinogenic (causing malformations in fetuses) and teratogenic (carcinogenic). There are reports that hairdressers have an increased risk of congenital malformations, spontaneous abortions, childhood cancer, and other developmental problems. An older literature dating back to the 1980s indicates that hairdressers may be at greater risk for developing leukemia, cancers of the bladder and GI tracts, as well as other diseases. Nasca reported in the Journal of the NCI that women who use hair dyes are at greater risk of developing breast cancer.

Women who use beauty products regularly throughout pregnancy worry about their health and the potential for exposure to carcinogenic chemicals. Fears of chemical exposure and absorption that can pose risks to the fetus are reasons why many women avoid dyes during pregnancy.

Even more concerning is the fact many women have children later in life, which means that hair dyes are likely to become more popular. Combining hormonal hair growth increases during pregnancy and an increase in the need for coloring as women age, clearly predicts an increase in use of these products.

All of this being said, I decided to write an article reviewing the current literature regarding safety concerns for hair dyes. This will allow you to make an informed decision about whether to use them. However, overall conclusions should be based on the methods of dye application (personal or hairdresser), the color used, frequency of coloring and differences between the various product components.

How is hair dye classified?

There are three types of classifications:




The chemical composition of hair dyes determines which classification they are placed.

Permanent dyes make up 75% of all hair colors. They are formed by the oxidation of dye precursors with hydrogen peroxide. This permeates the hair fiber and produces the desired color. Permanent hair dyes can be applied by using a brush or by a hairdresser. Permanent hair dyes can make dramatic hair color changes. They don’t wash out, and they last until your hair grows or is cut.

Semi-permanent colors make up approximately 20% of all dyes. They penetrate the hair cortex directly without the need for oxidizing agents. The color will last between 6-12 washes. These dyes are usually applied by hand and used to highlight or cover gray. They are also available over-the-counter.

These temporary dyes make up about 5% of all hair colors and can be used in one wash. This hair coloring is applied to the cuticle layer and stays until it is removed. Although it won’t lighten hair, it can be used to enhance natural colors, tint hair another color or add highlights to natural hair. It can also be used to remove yellowish hues from gray hair and cover some gray hair.

What hair dye chemicals can cause pregnancy concerns?

Numerous studies have reported an increase in the risk of developing childhood brain tumors (CBT), due to exposure to N-nitroso chemicals, which are commonly found in hair dyes.

There are two broad categories of N-nitroso compounds



The unstable nitrosamides do not require enzyme activation. They are more likely to cause tumors at the site of exposure. They can cross the placenta in rats and cause neurocarcinogens.

The carcinogenic agent nitrosamines are commonly found in beer and tobacco smoke.

Aromatic amines, which are chemicals found in hair dyes, can be converted to nitrosamines. This bioactivation is required for nitrosamines to cause tumor formation at places other that the original exposure site. NOC-related aromaticamines are hair dyes that contain ammonia-based solutions, hydrogen peroxide and coal-tar dyes. These agents are considered carcinogenic when administered orally to animals because they alter DNA. However, there is insufficient evidence to prove their carcinogenicity when used topically.

Other toxic chemicals found in hair dyes include phthalates, cobalt salts, formaldehyde releasing preservatives, lead acetate, nickel salts, 1,4-dioxane, diethanolamine/triethanolamine, and parabens.

What happens to the fetus when a woman is pregnant and uses hair dyes?
Routine use of many chemicals can expose the fetus to them as they are skin-permeable. Their toxicity is determined by the particular properties of the dye products as well as their ability to penetrate skin. Exposure can also be done by oral, inhalation, and ocular routes. These chemicals can cross the placenta to cause harm to the fetus. Many of these chemicals can be found in the body fat, and may also get into the mother’s milk.

What types of toxicities have been reported in pregnancy?
Many inconsistent results have been reported between hair dyes and different childhood cancers.

Studies have found a link between hair read more dye used in the mother’s hair and an increased risk of developing cancer as a child. Carcinogens and mutagens are especially dangerous to the immature nervous system. Exposure during the first trimester of the nervous development may increase the risk of brain tumors and cancer.

Neuroblastoma is the most common childhood cancer in children in the first year. It accounts for 6-10% of all pediatric tumors in developed countries. According to Kramer’s 1987 article in the Journal of the National Cancer Institute, children whose mothers were exposed to hair dyes in pregnancy had a 3 fold increase in risk. McCalls 2005 article in Cancer Causes and Control confirms this increased risk. According to Bunin’s 1987 study in Cancer Research, Wilms tumor was a form of cancer that affects the kidneys. Many chemicals used in hair dyes in 1987 have been removed (2-4-diaminoanisole and 4-amino-2 nitrophenol), but there are still some chemicals in N-nitroso aromatic amines that are carcinogenic to animals.

Another study from the West Coast found no association between hair dye use during pregnancy and pregnancies. (Holly, Pediatric Epidemiology 2002). A large study done by Effird Journal of Neuro-Oncology 2005 found no statistically significant association between hair dye use during pregnancy and childhood brain tumours. However, there was a 3fold higher risk of brain tumor in children with semi-permanent hair colors.

Are different hair dyes more dangerous than others?

Temporary dyes, which include semi-permanent dyes, are more toxic than permanent dyes during pregnancy. Semi-permanent dyes penetrated scalps more effectively than permanent dyes, according to studies on humans and monkeys. Semi permanent dyes do not contain oxidizing agents, which allow dye to irreversibly bind to hair shafts. Semi permanent dyes penetrate the scalp faster than permanent dyes. Semi-permanent dyes have a greater skin contact because they can be applied as a foam, rinse, or surfactant solution. This helps to increase skin uptake. Semi-permanent products for hair coloring may also contain nitro derivatives phenylenediamines, aminophenols, azo and aminoanthraquinone colors and N-nitroso compound that have been proven to be transplacental neural carcinogens in rodents.

Semi-permanent dyes can be applied by the individual, whereas permanent dyes could be applied by a hairdresser. Self-application exposes more skin to the sun, including hands, than when an outsider applies the dyes.

The toxicity of dye use was also higher in smokers than it was for non-smokers. Additional exposure to nitrosamines, and other carcinogens from cigarette smoke, was added to the carcinogens found in hair dyes.