A. The body does appear to sweat out toxic materials — heavy metals and bisphenol A (BPA), a chemical found in plastics, for instance, have been detected in sweat. But there’s no evidence that sweating out such toxins improves health.
“The claims for the benefits of saunas and other sweat-inducing treatments are not backed by science,” said Dr. Harriet Hall, a retired family physician and former Air Force flight surgeon, who edits the website Science-Based Medicine and is a co-author of “Consumer Health: A Guide to Intelligent Decisions.”
The concentration of metals detected in sweat are extremely low. Sweat is 99 percent water. The liver and kidneys remove far more toxins than sweat glands.
No one will ever be able to conduct a large enough study to link such low levels of chemicals with health problems, said Joe Schwarcz, a professor of chemistry at McGill University in Montreal. “It’s not figure-outable,” he said.
And removing tiny quantities of toxins doesn’t necessarily mean there will be any health benefit.
Dr. Schwarcz compared it to someone sitting in a bathtub worrying about drowning. Removing a dropper-full of water from the tub will theoretically reduce the risk — because the chance of drowning is lower in less water — but getting rid of so little water will be effectively meaningless.
So does it matter that people excrete small amounts of toxins in their sweat? “The fact is, nobody really knows,” Dr. Schwarcz said.
Author: Karen Weintraub