Evidence for early puberty in girls due to exposure to toxicants in personal care products
A recent study published in Human Reproduction examined the relationship between prenatal (before birth) exposure to several endocrine disruptors in personal care products and the timing of puberty in children. This isn’t a good news story, but it is a story that we want to share, because this is the only way the outcome will be different for future generations.
What we already know
Studies show girls now enter puberty at younger ages than they did previously. Early puberty has been associated with an increased risk of mental health problems, risky behaviours, and future breast and ovarian cancer in girls, and testicular cancer in boys. It has been suggested that the current obesity epidemic is a factor – overweight girls tend to enter puberty earlier – but there are suggestions that endocrine disrupting chemicals that mimic the body’s natural hormones might also contribute.
Exposure to toxicants (a toxic substance introduced into the environment) phthalates, parabens and phenols is widespread. A recent US study showed that 96% of women had detectable levels of phthalates in their urine and 90% had parabens in their urine. Given the in utero period is critical for the healthy development of reproductive organs, researchers investigated whether exposure to parabens, phthalates and phenols was associated with timing of puberty.
How this study was performed
This research was part of a longitudinal study of women during pregnancy that followed up their children (179 girls and 159 boys) from the age of 9 years. The researchers measured concentrations of phthalates, parabens, and phenols in urine collected from the mothers during pregnancy and, later, from their 9-year-old children. Puberty timing was assessed every 9 months in the children between the ages of 9 and 13 years using a widely accepted developmental milestone measure ‘Tanner stages’, which measures specific changes in the breasts and genitals.
What this study found
Mothers with high urine concentrations of triclosan (used as an antibacterial agent in some toothpaste and hand soap) and 2,4-dichlorophenol (a product of pesticide manufacturing) during pregnancy had daughters who were more likely to have earlier menstrual periods than mothers who had lower concentrations.
Mothers with high urine concentrations of monoethyl phthalate (a chemical used in personal care products with fragrance) during pregnancy were more likely to have daughters with earlier pubic hair development. There were no associations between maternal urine concentrations and puberty timing in boys.
A 9 years of age:
- Girls with high urine concentrations of methyl paraben or propyl paraben (used as preservatives in cosmetics) got their menstrual periods earlier on average than their peers with lower concentrations.
- Girls with high urine concentrations of methyl paraben had earlier breast and pubic hair development.
- Girls with high urine concentrations of propyl paraben had earlier genital development.
- Boys with high urine concentrations of propyl paraben had earlier genital development.
Limitations of this study
The authors raise a few notes of caution:
1. Because our bodies metabolise (breakdown) these chemicals, the effects may be greater than observed in this study.
2. This represents a single population of people (Latina children of low socioeconomic status) and may not be relevant to other populations.
3. It’s possible that children who go through puberty earlier use more personal care products because they have gone through puberty. Therefore, rather than the high exposure to these chemicals being responsible for the early puberty, it may be a consequence of the early puberty (reverse causality).
This study provides evidence that prenatal and peripubertal (around the time of puberty) exposure to certain phthalates, parabens and phenols present in personal care and consumer products is associated with pubertal timing in girls, but less so in boys. This study contributes to a growing literature that suggests that exposure to certain endocrine disrupting chemicals may impact timing of puberty in children.
What this might mean for you
This is a strong study design that follows the same population over a long period of time. In this space, causality studies, i.e., those studies that show that 1 thing causes another, are unlikely to be performed. The evidence for harm of these chemicals is significant enough that ethics committees are unlikely to allow a randomised controlled trial where some people were knowingly exposed to these chemicals and others were not, and the outcomes compared. Therefore longitudinal studies like this one, that show associations, are probably as good as the evidence will get. There is a need to repeat this sort of study in other populations to confirm that this is not an effect specific to this population of women and their children. If these studies started today, we would be waiting another 10+ years for more evidence.
If this evidence is enough for you to consider making some changes, as general guidance we recommend:
- Avoiding personal care product use and exposure for children
- Choosing personal care products without parabens, phthalates and phenols
- Minimising use of antibacterial soaps and sprays – most of us aren’t exposed to pathogenic bacteria as often as we might think. Our skin needs bacteria to thrive, and antibacterials cannot differentiate between the good guys and the bad guys
- Buying organic / pesticide free products (and food)
- Minimising personal care product use for yourself – stick to the basics, gently cleanse your skin and keep it hydrated, if you need a fragrance, try diluted essential oils. Our children learn most from observing us, so let's lead by example
You can check the safety of some cosmetics using Environmental Working Group (EWG) skin deep cosmetics database at https://www.ewg.org/skindeep/.
eat for baby musings
After reading this study, we got to wondering, has it stopped being OK to be human? Are we no longer comfortable with our natural human functions, appearances and even body odours? The colour of our nails, lips and cheeks are fine just as they are, so why do we feel the need to change them with potentially toxic chemical colours or fragrances?
For the health of our daughters and their daughters, we must try to get back to focusing on the incredible functions our bodies’ perform, rather than its form.
For some, this new piece of evidence may be enough. Do away with it all. Get back to basics. Embrace who we are in our most raw form. For others, that is inconceivable. We understand accentuating features is something that's an enjoyable ritual for many and one that some simply wouldn't give up. And that's OK too. Today, there are plenty of brands that look to nature and use only organic materials, offering safer products for people to use. We recommend looking for certified organic products and those that provide a long list of potentially harmful ingredients that aren't included in the product.
Reference to original study
Harley KG, Berger KP, Kogut K, Parra K, Lustig RH, Greenspan LC, Calafat AM, Ye X, Eskenazi B 2019. Association of phthalates, parabens and phenols found in personal care products with pubertal timing in girls and boys. Human Reproduction, 34(1):109-117