Sunscreens don't affect reproductive hormones: the study results cannot be extrapolated to prepubertal children, who may absorb more of the chemicals.(Gynecology)

Although the chemicals in sunscreens are systemically absorbed and excreted in urine, they don't appear to have any impact on reproductive hormone levels in adults, even when used in amounts far exceeding the recommended application, Dr. Nadeem Janjua of Bispebjerg Hospital, Copenhagen, and associates reported.

But the investigators cautioned that the results of their small study can't be extrapolated to prepubertal children, who may be more sensitive to low levels of hormone action. "Young children have less developed elimination of drugs and larger surface area per body weight than adults, leading to a possible higher uptake and bio-accumulation. Thus, our results cannot exclude that a sunscreen treatment similar to the treatment given in this study might have adverse effects in children," they said (J. Invest. Dermatol. 2004;123:57-61).

Some chemicals contained in sun screens have been seen to exert an estrogenizing influence in human breast cancer cells and in rats.

The investigators used a combination of three popular sunscreens available in Europe to test the level of systemic absorption and excretion as well as the compounds' possible effect on reproductive hormones in 15 young men aged 23-29 years and 17 postmenopausal women aged 54-86 years. Postmenopausal women were chosen to ensure a female population with stable levels of reproductive hormones.

The subjects were instructed not to exercise; sunbathe; or consume caffeine, nicotine, or alcohol during the study. Nor were they allowed to use any other skin preparations.

During the first week of the 2-week study, subjects applied 2 mg/[cm.sup.2] of Essex cream to their entire bodies once each day. During the second week, they applied the same amount of Essex cream containing 10% by weight of the three sunscreens: benzophenone-3 (BP-3), 3-(4-methylbenzylidene) camphor (4-MBC), and octylmethoxycinnamate (OMC).

Blood samples were taken at the same time each day, and morning urine was collected. The investigators measured FSH, LH, sex hormone-binding globulin (SHBG), testosterone, and estradiol. Inhibin B was measured in men but not in women.