During their fertile years, half of the population uses menstrual products several days a month. Their continued use in direct contact with the genitals exposes menstruating people to the chemicals present in their composition. These include plasticizers, which are typically added to plastics to make them more flexible and can be harmful to health. This is the case with phthalates, which act as endocrine disruptors and are known to be present in high concentrations. However, other additives other than phthalates were unknown in menstrual products.

There are many myths surrounding menstruation and, in general, female sexual health. The lack of medical research into women's bodies, but also taboos and sexism, have led to many problems being explained in secret or solved through word of mouth and folk medicine. One of the most widespread beliefs is that bathing during menstruation causes the bleeding to stop: we explain why this isn't true.

When she was just eight years old, Lua began to complain that her breasts were hurting, and her mother, Marcela Sáenz, a nurse, noticed that she had already developed a breast bud—breast growth—which is generally the first sign of the onset of puberty in girls. "I saw that it wasn't normal, that it was too early, and we went to the Primary Care Center for an evaluation, and from there we were referred to the endocrinologist at San Juan de Dios Hospital," explains Lua's mother. There, they performed tests, including blood tests and a bone X-ray of her hand, to assess whether her growth was in line with her age. They also assessed her birth weight and development.

On February 11th we celebrate the International Day of Women and Girls in Science. It seems incredible that we still need reminders of the need to make women scientists visible and promote vocations, but this year I would also like to remember that – perhaps as a consequence of the fact that women were not encouraged to access science careers for years – women have not been the subjects of biomedical research. I suppose we were considered unimportant. Little is known about the physiology and metabolism of the female biological sex, beyond its ability to conceive and bear children. Infertility is a taboo, and menopause is not talked about. Even in old age, men and women are not equal, and neither the medications, nor the doses, nor the diseases that affect us are similar or comparable.