Researchers tested urine samples of 55 adults before and after an evening of smoking water pipes at a hookah bar.
The participants had elevated levels of tobacco-related chemicals in their body, which may increase the risk for cancer.
The experts said water pipe smokers also had substantially higher levels of nicotine.
The chemical is known to be addictive and can alter developing brains.
In other health news, a study of older adults finds increased evidence of "silent strokes" in the brains of migraine sufferers.
The brain injury is likely caused by a blood clot interrupting blood flow to brain tissue.
It's symptomless but raises the risk for future strokes.
It's unclear whether treating migraines to reduce their severity or number would help cut down the number of silent strokes.
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