And it's a big one 

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We've heard about gross items on restaurant tables and germs on planes, but apparently there's one more danger lurking where you'd least expect it.

According to Dr. Robert Hayden, Georgia spokesperson for the American Chiropractic Association, injuries sustained while at the hair salon are rare, but can be serious if not life threatening. It seems the culprit is the design of shampoo bowls, which could be to blame for more than just a few minutes of discomfort.

The first (and most catastrophic) scenario that can result from using a shampoo bowl at the salon is a condition Dr. Hayden refers to as beauty parlor stroke. It occurs when blood flow to the two arteries that run through the bones in the back of the neck are obstructed.

Dr. Hayden explains, if a client is lying down with their head back in a shampoo bowl for an extended period of time (even for as little as 3-4 minutes), the positioning may decrease blood flow through those arteries, which sets up the potential for a stroke particularly in people who have previously suffered a stroke. Immediate symptoms include dizziness, nausea, blurred vision, and perhaps weakness or an inability to move the extremities. Leaning over the sink, rather than back, can mitigate much of this risk.

While Dr. Hayden said beauty parlor stroke is rare, cases have been reported and both clients and salon professionals should be on the lookout for warning signs. "There are many hairdressers that I've talked to that really are not fully cognizant of the potential for injuries. They might not have seen it yet, or they just aren't aware."

Being aware of risk also includes thinking about minor injuries, like muscle straining, that are much more likely.

"It's important to note that the human head weighs usually between 13 and 15 pounds," said Dr. Hayden. "You essentially have a bowling ball at the end of a relatively small and fragile stalk, which is the neck." When positioned in a shampoo washbowl, the neck is hardly supported, meaning straining can happen. In order to help lessen the risk of straining, ask your stylist to put a hand behind your head and assist you to a seated position after your shampoo.

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To ensure you're caring for your back and neck throughout your salon visit, keep both your feet on the floor and your knees level whether you're in the stylist's chair, at the shampoo bowl, or sitting under a dryer.