In 2011, the Archives of Environmental Contamination and Toxicology published the results of a clinical study that wanted to answer this question. A Canadian gynecologist overseeing the health of pregnant mothers suffering from various exposure to a variety of environmental toxicants wanted to find solutions he could feel confident about recommending clinically to help these expectant moms get healthy. He had established various methods to help diminish the burden of toxicants before giving birth, but no one technique has proven to remove everything.2
The physician hoped to build on the limited existing evidence3, 4, 5, 6 from drug rehabilitation using sauna therapy proving sweat excreted cocaine, amphetamines, crystal meth and morphine. Frustrated by the lack of research and understanding of how toxicants are eliminated from the body, as well as a growing knowledge of the potential harmful impacts of accumulating toxic elements in his patients, he undertook a study himself.
The study on a cohort of 20 individuals was approved by the Health Research Ethics Board of the University of Alberta to provide evidence relating to the excretion of toxic elements by the human body. A primary goal was to determine if sweating through sauna therapy may facilitate the excretion of some retained toxic elements. Researchers understood sauna therapy increases thermal load to the body, initiating an autonomic nervous system thermoregulatory heat-loss response: body temperature rises, the hypothalamus detects the rise and responds by directing the heart to increase circulation to the skin. Some toxicant accumulation can impair that process.7
Giving a urine sample or having your blood drawn is common practice for testing for evidence of toxic substances in the body. The BUS Study assessed the concentration of various toxic elements (how much or how strongly they appear) in three body fluids: blood, urine, and sweat in 20 participants (nine men and 11 women ranging in age from 21 to 68).
- 10 healthy participants
- 10 participants with various health problems
- Collected samples of blood (200-ml), urine (morning), and sweat (100-ml)
- Analyzed for approximately 120 compounds in seven categories
- Toxic Elements – heavy metals & metalloids
- Plasticizers – phthalates & bisphenol A
- Solvents – benzene, xylene, etc.
- OC Pesticides – DDT, DDE, etc.
- PFCs – PFHxS, PFOS, PFOA, etc.
To get the sweat samples, the team induced sweat in participants through infrared sauna (10 participants), steam sauna (seven participants), and exercise (three participants).
The BUS researchers confirmed that toxic elements were found in all three body fluids. The results for metals and metalloids in the blood samples matched expectations and were similar to other published findings for blood. Many toxic elements appeared to excrete more through sweat than blood or urine, including cadmium, nickel, lead, bismuth, manganese, aluminum, cobalt, chromium, uranium, thallium, arsenic, mercury, copper and selenium.7
The researchers reported some toxic elements hide in tissue and come out in sweat, not blood serum.
They also found that infrared sauna appears to work better for bismuth, cadmium, chromium, mercury, and uranium than regular sauna or exercise.7
Cadmium is found in cigarette smoke, batteries, solar cells, plastics and pigments. In the BUS study, half the participants had no detectable cadmium in blood or urine, but 80% had notable levels in sweat. It can be stored in tissues with no evidence in blood or urine. Sweat can release stored cadmium.
Mercury is found in dental amalgams, thermometers, fluorescent light bulbs, electrical switches, mining, in the air, and fish/shellfish. In the BUS study, researchers noted that some participants (15%) had no detectable levels of mercury in their blood, but ALL of those participants had mercury in their sweat.
Nickel is found in cell phones, e-cigarettes, jewelry for piercings, and clothing fasteners.
Lead is found in some paint, pipes, pottery, cosmetics, bullets, and art supplies.
Bismuth is found in cosmetics and pharmaceuticals.
Manganese is found in water, gasoline, and tobacco smoke.
Aluminum is found in water, food, medicines, and personal care products like deodorant.
Sweating is an effective way to eliminate many retained toxic elements from the human body. Some elements are removed very readily; some less so. Generally, toxic elements were excreted much more readily than essential elements. Some toxic elements may be hidden in tissues with no sign on blood or urine testing – serum and urine bio-monitoring less than ideal. Some toxic elements that do not show in blood or urine may be released during sweating, and it should be considered as a biomonitoring tool.7
Researchers also reported their findings on other compounds in two additional articles. The most significant to note are their findings on Bisphenol A (BPAs), an industrial chemical used to make a hard, clear plastic known as polycarbonate used in many consumer products, including reusable water bottles and baby bottles. It’s also found in adhesive coatings - protective lining on the inside of metal-based food and beverage cans. BPAs are known hormone disruptors. Finding: 14 of 20 participants had BPA in sweat but not in blood.8
The results also showed not all chemical compounds are found as much in sweat. Their analysis of the carcinogenic perfluorinated compounds (PFCs), a family of fluorine-containing chemicals with unique properties to make materials stain and stick resistant, concluded sweat is not an effective way to eliminate PFCs.9