When you put sunscreen on your skin you probably assume that it stays right where you put it, doing the very important job of protecting your skin from the sun. However, many of the chemicals that protect skin from the sun's harmful rays are absorbed very efficiently and can travel throughout the body where they have a quite different and disturbing effect.

Sunscreen can contains quite a cocktail of chemicals, many of which have been tagged as endocrine-disrupting chemicals or EDCs which can mimic hormones and alter the activity of the endocrine system. These chemicals have been linked with male and female infertility.

These potentially harmful hormone mimics can eventually end up in sperm and may reduce male fertility via a variety of mechanisms which are becoming more apparent since the development of new more sensitive sperm test. In short, you may want to consider carefully the kind of sunscreen that you purchase to minimize your absorption of EDC chemicals.

In a 2014 study (1) published in the journal EMBO lead researcher Niels E. Skakkebaek, stated:

"For the first time, we have shown a direct link between exposure to endocrine disrupting chemicals from industrial products and adverse effects on human sperm function..."

This study tested hundreds of chemicals to assess the impact of commonly used chemicals upon sperm function, a few of these substances, particularly UV filtering sunscreens, the anti-bacterial agent Triclosan which is used in toothpaste and soaps and a phthalate (di-n-butylphthalate (DnBP)) which is used in plastics demonstrated adverse effects upon sperm.

Sperm motility may be particularly vulnerable to the effects of EDCs at concentrations typical of body fluids; EDCs may be able to change sperm swimming behavior and may render sperm less sensitive to progesterone and prostaglandins.

The sequence of events that underly sperm generation and egg fertilization are carefully and precisely coordinated, the interference of EDC chemicals may be able to change swim patterns, hinder sperm penetration of the egg and alter fertility in myriad ways. The study concluded that:

"Here, we provide a direct link between exposure to EDCs and potential adverse effects on fertilization in humans. About 800 omnipresent man-made chemicals are suspected to interfere with the endocrine system. To this day, the majority of these potential EDCs have not been evaluated for their action in humans."

If you are choosing a sunscreen you may like to check out the annual report (2) of safe sunscreens prepared by the Environmental Working Group (EWG.org). Some progressive fertility-friendly sunscreens use tiny particles of zinc oxide and titanium which sit on top of the skin and reflect UV rays, minimizing or avoiding the use of UV sunscreen chemicals.

Careful sunscreen manufacturers also avoid the use of phthalates and other endocrine disrupting chemicals such as PABA so that you can protect yourself from the sun without causing hormonal chaos and harm to fertility.

Reference:
Direct action of endocrine disrupting chemicals on human sperm, Timo Strünker, et al., EMBO reports, doi: 10.15252/embr.201438869, published May 2014. European Molecular Biology Organization news release, accessed 1 June 2014.
http://www.ewg.org/2014sunscreen/