Endocrine Disruptors in Cosmetics!? Blog Version

TLDR: not something you actually have to worry about.

The endocrine system?

The endocrine system is one of our body systems really focused on hormones. Hormones are signaling molecules that are sent to different parts of the body to stimulate a certain change.

Certain chemicals we produce will fit into certain receptors to cause the activation of gene expression to eventually make proteins, which are those signaling molecules.

For example, estradiol will fit in the estrogen receptor to cause an effect - e.g. regulation of female reproductive cycles.

What does endocrine disruption mean?

When we hear this term, it’s concerned with: Estrogen, Androgens, Testosterone and Steroidogenesis (EATS).

Endocrine disruption is where a chemical either acts like a hormone or interferes with a hormone. For example, a chemical may fit in the estrogen receptor to cause gene expression which translates to an estrogenic effect - e.g. a dog goes into heat.

*IMPORTANT*

Most regulatory definitions of endocrine disruption stop at the gene expression point, rather than the outcome. They are also determined by assays that are not human relevant.

For example, they won’t have estradiol in the scenario, which a chemical would have to outcompete in the human body to get in that receptor and cause an effect. Estradiol has a very strong affinity for the estrogen receptor, so the chemical in question should have a comparable or stronger affinity, or the concentration of said chemical should be high enough to make up for the lower affinity. Gene expression in an assay does not equal an estrogenic/endocrine disrupting effect in reality. 

These assays are very sensitive to try to find e.g. potential birth control options, which it turns out, is pretty dang hard. E.g. We've been trying for decades to get a viable male birth control pharmaceutical, and still haven’t been successful.

Do cosmetics cause endocrine disruption?

Realistically, probably not.

The problem with cosmetic ingredients (e.g. parabens, UV filters, phthalates - relevant to what’s allowed and at what level) - while in certain assays, they have been show to activate the e.g. estrogen receptor to cause gene expression, they’re affinity for estrogen is dramatically lower than estradiol. E.g. The affinity of parabens in cosmetics is ~10,000x lower than estradiol. So, for parabens to have the chance to have an estrogenic effect, they would have to be used at massive concentrations, which IS NOT RELEVANT to cosmetics. E.g. The EU maximum concentration for methylparaben is 0.4% as a single ester and a total concentration of 0.8% of paraben mixtures. So even if the topically applied parabens get into your blood system (big if, and if they do, the concentrations will be even lower), the dosage is too low to compete with estradiol.

Why is there so much noise in the media about endocrine disrupting cosmetics?

Unpopular opinion - sensationalism.

This post is based on my Endocrine Disruption in Beauty? Podcast with toxicologist Lyle Burgoon PhD. If you want a deeper dive into the subject, the episode is a must listen. Tune in with the widget below!