One of the concerns during pregnancy is whether women can still keep coloring hair. These concerns arise from the fact that many of the dye precursors are carcinogenic. Research regarding the impact of these dyes on the fetus is limited. To date the dyes have not been proven unsafe. But, doctors tend to err on the safe side advising their patients to wait after the first trimester to dye hair. For those who would rather avoid hair dyes altogether, they often consider bleaching hair during pregnancy. But the question is: how safe is bleaching?
Hair bleaching uses hydrogen peroxide and salts of persulfates. In brief, the hydrogen peroxide gets activated in the presence of persulfates and oxidizes the pigments in hair(melanin). The change in the chemical structure of these pigments cause them to lose their color. Thus bleaching occurs. Learn more about the bleaching process here.
Hydrogen peroxide is corrosive to skin, eyes, and mucous membranes at high concentrations (>10%); lower concentrations like those used in bleaching (3-6%) may cause irritation. Source: CDC.
Other effects occur from inhalation or ingestion and may include gas embolism, gastric irritation, gastric distension and emesis, an accumulation of fluid in the lungs, unconsciousness, and respiratory arrest. Again this is likely to happen only at high concentrations.
Symptoms become more severe as the concentration of hydrogen peroxide increases. In a well ventilated room, most people shouldn’t be experiencing any irritation or allergic responses when bleaching hair.
Persulfate powders such as potassium persulfate can cause severe irritations even at low levels. Special care needs to be taken to avoid inhaling the powder during the mixing of the powder with the hydrogen peroxide.
Toxnet reports the following.
MILD TO MODERATE TOXICITY for potassium persulfate:
Irritants may cause swelling, redness, and pain at any site, especially at mucous membranes. The mouth, nose, and eyes are commonly affected. After inhalation, cough, tachypnea, and wheezing are common. With ingestion, nausea, vomiting, and diarrhea are common. With dermal exposure, redness, swelling, and pain may occur.
Bleaching hair during pregnancy
During pregnancy the volume of blood in the woman’s body increases. This makes her even more sensitive to chemicals. Additionally, certain smells can also trigger unwanted symptoms such as nausea, light headedness etc.
For that reason, if you feel that the hydrogen peroxide or persulfate seem to be causing symptoms like itchy throat, tearing, sneezing etc. you should stay away from bleaching hair during pregnancy. Chances are that your body is not reacting well to the chemicals. It is not clear if there could be any impact to the fetus as well. There is no reported or conclusive data in that respect. But again, if bleaching is making you sick in any way, better stay put for the next few months, and find alternatives.