Chemicals may affect onset of puberty

The European Society for Human Reproduction and Embryology (ESHRE) Annual Congress has just taken place virtually last week. The online delegates were warned of concerns about chemicals found in everyday cosmetics and personal care products. Their statement said, “Several chemicals in personal care products were associated with earlier puberty in girls.”

Interference and disruption of hormones

These chemicals are known as endocrine-disruptors. They have been shown to interfere and disrupt hormone systems in the body.  In high doses they are known to cause cancerous tumors, birth defects, and other developmental disorders. Systems in the body are controlled by hormones and can be derailed by endocrine disruptors. This includes sexual reproductive systems, which are governed by hormones like oestrogen and testosterone. Specifically, endocrine disruptors may play a part in sexual development problems such as feminising males or masculinising females.

Professor Kim Harley, Berkeley University, USA presented her research to the ESHRE conference. It suggests that endocrine disruptors found in everyday cosmetics and in body-care products may affect the timing of puberty, particularly in girls. According to Professor Harley, more research is now needed into the health effects of these chemicals. She reported that the timing of puberty in girls has been getting earlier throughout this century. The average age of girls at onset of breast development has decreased by one year over the past 40 years.

Adverse female reproductive outcomes

The global obesity epidemic on its own does not entirely explain this. Professor Harley believes these endocrine disruptor chemicals, which are found in cosmetics and personal care products such as sunscreen, shampoos and make-up may explain the situation. The effects on females of some of these chemicals has been known for some time. For instance, in 2013 a study in Massachusetts, USA found that exposure to phthalates (a type of endocrine disruptor chemical) was linked to reduced fertility in IVF treatment. The authors of that study wrote, “Our data support the hypothesis that exposure to specific phthalates might lead to adverse female reproductive outcomes.”

Although some regulators, including the EU, have taken action to ban their use and continue to do so, consumers can also decrease their exposure by not buying products containing these chemicals.

Professor Harley said, “If you want to lower your exposure to these chemicals, being a savvy consumer and buying products without them is the way to reduce exposure.”

What are endocrine disruptor chemicals?

Professor Harley’s study analysed the impact of 7 of these chemicals, which belong to chemical classes known as phthalates, phenols and parabens.


A generic chemical structure of the phthalate class of endocrine disruptor chemicals

Specifically, she looked at:

  • Monoethyl phthalate (MEP)
  • Mono-n-butyl phthalate
  • Mono-isobutyl phthalate
  • Methylparaben, and propylparaben
  • Triclosan
  • Benzophenone-3
  • 4, and 2.5-dichlorophenol

The trick to avoiding these chemicals is to check the label carefully. You can also look up the ingredients of personal care products such as shampoos, makeup, deodorants online. The positive news from Professor Harley’s presentation is that the use of these chemicals is reducing in some instances. For example, measurements of MEP and triclosan urine samples have decreased over the past decade, along with some reduction in methylparaben. Professor Harley hopes that a greater general and regulatory awareness of their potential adverse effects will lead to further reductions in their use in the future.