Is nail varnish truly a risk for pregnant women?

Pregnancy is a time of significant physiological and hormonal changes. It requires the expectant mother to consider two individuals, herself and her baby, and to be doubly cautious about the products she uses, particularly those related to skincare. Indeed, certain ingredients can penetrate the skin or be inhaled and enter the bloodstream before affecting the health of the foetus. Viewed by some as potential sources of exposure to endocrine disruptors, nail varnishes are also under scrutiny regarding their use during pregnancy.

Some nail varnishes contain compounds that are contentious during pregnancy.

Among the most concerning ingredients are formaldehyde, toluene, phthalates, and acetone, which can pose risks to foetal health. Formaldehyde is a compound classified by the European Union as a "probable carcinogen". It is also an endocrine disruptor, capable of altering the hormonal system. As for the phthalates found in some nail varnishes, they are also suspected of hindering foetal development, particularly by disrupting its hormonal system.

Toluene, on the other hand, is a neurotoxic solvent. Inhalation can lead to neurological disorders. It is also associated with a heightened risk of foetal malformations. A clinical case supports concerns about exposure to toluene during pregnancy. It describes the situation of a newborn with an abnormally large head. A scan conducted in the hours following birth revealed hydranencephaly: a severe brain malformation, characterised by the absence of both cerebral hemispheres, replaced by a large cavity filled with fluid. In this case, the mother worked in the automotive industry, where she was exposed to solvents, including toluene, used for cleaning paints. However, this molecule is also present in some nail varnishes. Although it is difficult to establish with certainty a direct link between exposure to toluene and this malformation, and the mother's exposure to toluene was much greater than what would occur in a typical nail varnish application, this case calls for caution.

Finally, acetone, found in many nail varnish removers and in some nail varnishes, is a highly volatile solvent that can easily be inhaled. Once absorbed, acetone crosses the placental barrier and can reach the foetus. Although it is metabolised by the liver, a portion of the acetone can still affect the baby's development. Moreover, acetone is known to exacerbate nausea, a common symptom during pregnancy, making its use even more problematic for expectant mothers. The still problematic composition of many nail varnishes is the reason why many women choose to avoid wearing nail varnish during their pregnancy.

Studies regarding the risks posed by the use of nail varnish during pregnancy remain limited and the results are sometimes contradictory. Some research, conducted with very large panels, exceeding 1,000 women, suggest that increased exposure to certain cosmetic products, including nail varnishes, could be associated with risks of obstetric complications, such as premature births or babies with a birth weight below average. However, other studies, also conducted on a large scale, have not been able to establish such a relationship. It should be noted that these various studies did not specify the frequency of use of cosmetic products nor their composition, factors that are nonetheless important to consider.

In the absence of definitive data, it is better to apply the precautionary principle and avoid manicures during pregnancy.

What about "n-free" nail varnishes?

In response to the concerns raised by nail varnishes, some brands have developed varnishes that aim to be safer, free from formaldehyde, toluene, or phthalates. These are the "n-free" varnishes, where n represents the number of problematic ingredients excluded. While these nail varnishes may seem appealing to pregnant women, it is important to note that the "n-free" labels are not based on a universally established standard, making it difficult to guarantee their safety during pregnancy.

• FANUCCHI M. & al. Formaldehyde exposure during pregnancy. The American Journal of Maternal Child Nursing (2015).

• ALBOUY-LLATY M. & al. Endocrine Disruptors and Pregnancy: Knowledge, Attitudes and Prevention Behaviors of French Women. International Journal of Environmental Research and Public Health (2017).

• MCGLYNN K. A. & al. Maternal use of personal care products during pregnancy and risk of testicular germ cell tumors in sons. Environmental Research (2018).

• XIAO J. & al. Maternal cosmetics use during pregnancy and risks of adverse outcomes: a prospective cohort study. Scientific Reports (2019).

• AKYOL S. & al. Hydranencephaly in a newborn due to occupational toluene exposure during pregnancy: a case report. Acute and Critical Care (2022).

• RALLIS E. & al. The Risk of Using Cosmetics and Cosmetic Procedures During Pregnancy. Applied Sciences (2024).