Arsenic, cadmium, lead, and mercury in sweat: a systematic review.

Plain-language summary

This review set out to see whether sweating clears toxic metals from the body. It pooled 24 studies that measured arsenic, cadmium, lead and mercury in sweat, compared those levels against blood and urine, and tracked how they shifted with different ways of sweating, including sauna and exercise. In people with heavier exposure or a heavier body burden (the amount of the metal already stored in their tissues, nothing to do with body weight), sweat generally carried higher concentrations than plasma or urine did, and excretion through the skin could match or surpass what left in a day of urine. Arsenic excretion through the skin was severalfold higher in exposed people than in unexposed controls, and cadmium was more concentrated in sweat than in blood plasma. The studies varied widely in how they collected sweat and in who they studied, so none of them establishes how much sweating it would take.

Key findings

• Sweat often had higher levels of arsenic, cadmium, lead, and mercury than blood or urine.
• People with higher exposure to these metals excreted more of them through sweat.
• Endurance exercise led to higher lead levels in sweat compared to intense exercise.
• Repeated sauna sessions normalized mercury levels in one case report.