A small study suggests that skin tattoos may hinder the ability to sweat, raising concerns for people with extensive tattooing during physical exertion in hot weather.

By the numbers — Researchers from Alma College in Alma, Michigan, recruited 10 people with skin tattoos on one side of their body, but not on the corresponding spot on the opposite side of their body. For all 10 participants, sweat rates from the tattooed skin were significantly lower than for their nontattooed skin. On average, sweat rates from tattooed skin were 53 percent lower than from nontattooed skin. For nine of the 10, sweat from tattooed skin had a higher concentration of sodium than sweat from nontattooed skin, suggesting the ability of sweat glands to reabsorb sodium was impaired by the tattoo.

Bottom line — The limited size of the study prevents any strong conclusions from being drawn without further research, but raised concerns whether extensive tattooing could impair the body’s ability to cool down through sweating. That could have significant consequences for endurance athletes who compete in hot weather, or for soldiers or other physical laborers who work in extreme conditions.

The design of the study could not determine whether the impaired sweat rates would have any detrimental effect on health or physical activity. It’s possible that other nontattooed parts of the skin can compensate for the diminished sweat rates. Even if the findings hold up with further studies, it’s still unclear how much skin would have to be covered by tattoos for people to be affected in any real way.

— Markian Hawryluk, The Bulletin