Young women aren’t the only ones showing the effect of beach vacations: In a study of 681 white seven-year-olds in Colorado, every vacation near the water was associated with a five percent increase in small moles (≤ 2 mm). Most children are born without moles, which tend to be acquired during childhood. Since a greater number of moles means a higher risk of developing melanoma, these increases in children are a cause for concern.

The researchers, led by Lori Crane, PhD, MPH, at the Colorado School of Public Health, in Denver, interviewed parents about all vacations their children had taken in “sunny locations” since birth. Sunny vacations by the water were most closely linked to increases in small moles. Because the number of days spent on these vacations and total UV dose did not appear to affect the number of moles the children developed, researchers proposed that the children reached a certain UV exposure “threshold” early on during waterside vacations, after which exposure had no influence on mole development.

The authors advise parents to choose trip locales carefully, and, when on vacation with their children, to limit UV exposure.