With increasing exposure to a witch’s brew of toxic chemicals in our modern world, could the ancient practice of sweating offer a modern-day detoxification remedy?
With the proliferation of toxic chemicals from industrial, agricultural and consumer product sources over the past century, bioaccumulation of these toxins is an increasing health concern [1]. Blood and urine sampling are commonly used to estimate toxin exposures and body burden, but research shows sweat testing provides additional useful exposure data and suggests sweat is an important route of elimination for many toxins [2]. In short, we don’t sweat purely for thermoregulation – sweating is also part of the body’s detoxification system.
Sweat as a Matrix for Biomonitoring Toxin Exposures
In 2010, Genuis et al. published results of the “blood, urine, and sweat” (BUS) study examining toxicant levels in these biological fluids collected from 20 individuals, 10 healthy and 10 with chronic health issues [3]. Numerous toxic elements like lead and cadmium appeared “preferentially excreted through sweat” compared to blood or urine levels, indicating, “Biomonitoring for toxic elements through blood and/or urine testing may underestimate the total body burden of such toxicants” [3]. Analyzing sweat, therefore, provides additional biomonitoring data on toxin exposures.
Preliminary research by Porucznik et al. explored using sweat patches to measure bisphenol-A (BPA) exposure as an alternative to reliance on variable urine measures given BPA’s short half-life [4]. They detected BPA in sweat patches spiked with BPA in the lab, but in their small sample of real-world patch testing, detected BPA above average background in only 3 of 50 patches worn for one week [4]. The lack of detection from patches worn on participants’ arms suggests either insufficient sweat collection from those locations or extremely low concentrations of BPA in naturally occurring sweat to allow measurement, highlighting complexities using patches to accurately capture toxins in sweat for biomonitoring [4].
Mechanisms and Efficacy of Toxin Excretion in Sweat
What enables sweat to serve as a route of elimination for accrued toxins? With heat exposure, circulation to the skin increases, delivering toxicants stored in tissues to sweat glands [3]. Lilley et al. showed with radioisotope-labeled lead applied to worker’s skin that sweat lead levels increased post-exposure even though blood and urine levels were unchanged, providing “strong evidence that the skin is capable of excreting certain heavy metals” [5]. Dermal application also increased lead in saliva, pointing to both eccrine sweat glands and sebaceous glands in the skin as toxin elimination pathways activated by sweating [5].
Studies report sweat facilitates the elimination of several potentially toxic substances. Genuis et al. found levels of lead, mercury, arsenic and cadmium elevated in sweat versus blood or urine samples in some participants [3]. Increased loss of cadmium and lead into sweat has also been associated with lower blood levels of these metals in exposed workers [6,7]. BPA and phthalates likewise appear in sweat and may preferentially accumulate in lipid-rich sweat secretions [3,8]. Sweating also enhanced excretion of persistent flame retardants and chlorinated pesticides in rescue workers and bisphenol-A in experimental trials [9,10].
For mercury, long used in mining and hatmaking, sending poisoned workers to warmer climates to “work in the heat (presumably to sweat out the ‘vapors’) was a common and effective strategy centuries ago” at reversing tremors and ulcers [11]. Modern research supports sweating as a clinically useful intervention for reducing mercury burden as well, with repeated sauna use progressively lowering mercury concentrations in a case report [12].
A 2016 study provides additional evidence that inducing sweating facilitates elimination of toxicants from the body [13]. Researchers found a variety of organochlorine pesticides (OCPs) and their metabolites were excreted in sweat after analyzing samples from 20 participants [13]. Sweat generally showed more frequent OCP detection and higher levels than blood or urine analysis, “suggesting that sweating may be efficacious in diminishing the body burden of many of these toxicants” [13]. The study detected DDT/DDE in nearly all participants and endosulfan in over half, indicating widespread exposure [13]. The highly lipophilic pesticides were more readily found in sweat versus blood, suggesting distribution and storage in fat tissue enables release into sweat [13]. There was little correlation between blood, urine and sweat levels for individuals, highlighting limitations of biomonitoring OCPs in just one compartment.
Induced sweating thus provides a clinical avenue to eliminate some accrued pesticides. The researchers conclude, “As DDT, DDE, DDD, methoxychlor, endosulfan sulfate, and endrin appear to be readily excreted into sweat, induced perspiration appears to be a potential clinical tool to diminish the body burden of these agents” [13]. Facilitating pesticide clearance may help prevent or mitigate health risks including metabolic, neurological, endocrine and reproductive dysfunction linked to bioaccumulation of these toxicants [13].
This study builds on prior evidence of utilizing sauna and exercise for removing OCPs as well as a range of toxic metals, phthalates, bisphenol-A, perfluorinated compounds, flame retardants and polychlorinated biphenyls (PCBs) [13]. As people have ubiquitous low-dose exposures to diverse toxicants that may accrue over time, sweating therapies provide accessible, non-invasive detoxification approaches with minimal side effects when precautions are taken. The cumulative impact of repeated sweating sessions merits further research in conjunction with clinical outcomes assessment.
Therapeutic Considerations and Contraindications
Sauna and exercise that induce sweating show potential as low-risk complementary treatments to mobilize and excrete accrued toxicants [3]. Adequate hydration and electrolyte intake helps offset losses in sweat. Sweating capacity may improve with regular sauna use indicating restored autonomic function [3]. However, underlying nutrient status and supplements to support detoxification pathways warrant consideration on an individualized basis [3]. For some with impaired capacity to sweat from autonomic dysfunction, skin brushing, niacin and incremental duration of heat exposure may help initiate sweating [3].
While generally well-tolerated, medical issues may contraindicate heat exposure, especially cardiovascular concerns in the elderly or those with unstable health conditions [14]. Healthcare practitioner guidance is prudent for those initiating a regimented sauna or exercise sweating protocol for health improvement.
Future Research Directions
Additional research is needed on utilizing sweat testing in biomonitoring for chemical exposures, bioaccumulation and pre/post-intervention assessments [3,4]. Robust clinical trials are also warranted to validate sweating protocols for toxin elimination and impact on disease outcomes [7]. Combination strategies like scheduling sauna use after showering post-workout or occupational exposure may hold promise and warrant further exploration as well [5]. Analyzing sweat composition and distribution factors for toxins will elucidate the mechanistic picture of sweating for detoxification to guide effective therapeutic interventions.
References
[1] Centers for Disease Control, Department of Health and Human Services. [Fourth National Report on Human Exposure to Environmental Chemicals](https://www.cdc.Originally posted: https://greenmedinfo.com/blog/detoxifying-through-sweat-overlooked-role-perspiration-toxic-chemical-excretion
