Bai Cao Shuang
StarPulvis Fumi Carbonisatus (herb-soot / plant chimney-soot, amorphous carbon)
Traditionally used for
- Cough & breathing
- Digestion
- Bowel health
- Menstrual & women's health
- Skin
☯ TCM Properties
Controls bleeding and disperses Accumulation
Traditional Chinese Uses
Bai Cao Shuang ("hundred herbs frost") is the fine plant soot scraped from chimneys and the bottoms of cooking pots after prolonged burning of grasses and wood — essentially amorphous carbon. Pungent and warm, entering the Liver, Lung and Stomach channels, it belongs to the Blood-regulating herbs that stop bleeding. Following the TCM principle that charred, black substances arrest hemorrhage, it is used both internally and topically for many kinds of bleeding, including hematemesis, epistaxis, uterine bleeding and metrorrhagia, bloody dysentery and bleeding hemorrhoids.
It also disperses accumulation and checks diarrhea and dysentery, and is applied externally to sores, eczema and wounds to stop bleeding and dry Dampness. Commonly given powdered, wrapped in decoction, or dusted on affected areas.
Relationships
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Botanical Description
Bai Cao Shuang ('hundred herbs frost') is not a plant but a processed mineral-organic substance: the fine, light, sooty deposit scraped from the underside of chimneys, stove-tops, and cooking-pot bottoms after the prolonged burning of grasses, straw, weeds, and miscellaneous herbaceous fuel. Traditionally collected from rural earthen or brick stoves, the soot is a black, weightless powder consisting largely of amorphous carbon together with condensed pyrolysis residues of the burnt plant material. It is sieved free of grit before use. In Chinese medicine it is administered internally to stop bleeding (haematemesis, epistaxis, uterine bleeding) and used externally on sores and ulcers; modern preparations are rare because of the changing technology of domestic cooking.
Active Constituents
Amorphous elemental carbon (soot particles)
Elemental carbon; combustion-generated black carbonConcentration: The bulk of the drug. Chinese materia medica describe the substance simply as carbon particles; no assay for carbon content exists in any of the standards that carry the drug.
The substantive content of this drug is what incomplete combustion actually produces, and that is not a single compound. What scrapes off a stove flue is a soot condensate: a black-carbon core with organic combustion products condensed onto its surface and inorganic ash mixed through it. The carbon core is chemically inert and is the basis for the traditional topical and haemostatic use, acting as an absorbent powder rather than through any dissolved constituent.
Polycyclic aromatic hydrocarbons (phenanthrene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, benzo[a]pyrene)
Polycyclic aromatic hydrocarbons; combustion by-productsConcentration: Never determined for the drug itself. Bai Cao Shuang is not in the 2020 Chinese Pharmacopoeia; it is carried only by provincial standards, among them the Shanxi materia medica standard of 1987, the Beijing materia medica standard of 1998 and the Hubei quality standard of 2018, and none of these sets a PAH or benzo[a]pyrene limit. For scale: particulate-phase PAH emission factors from solid fuels burned in Chinese domestic stoves run from a few mg/kg of fuel for clean wood, about 30 mg/kg for crop residue, to about 200 mg/kg for raw bituminous coal; across biomass fuels generally, total PAH yields of 5 to 683 mg/kg have been reported depending mainly on burning conditions. Benzo[a]pyrene is a small percentage of the total, but PAHs partition onto the particulate phase, which is exactly what flue soot is.
This is the real and citable carcinogenicity question about the drug. Soot is classified by IARC in Group 1, carcinogenic to humans, on the basis of over two centuries of scrotal and skin cancer in chimney sweeps and of raised lung cancer in Scandinavian sweep cohorts; benzo[a]pyrene is itself a Group 1 carcinogen requiring metabolic activation via CYP1A1. The IARC evidence is for dermal and inhalational occupational exposure rather than for oral dosing, and no study has measured PAHs in the medicinal article, so the size of the risk from a 1 to 3 g oral dose is unquantified. Absence of an assay is not evidence of a low load: the drug is by definition the condensed particulate phase of woodsmoke.
Inorganic ash: potassium, calcium and silicon salts
Alkali and alkaline-earth mineral ashConcentration: Not specified in any standard. Varies entirely with what was burned and with how much fly ash is entrained in the flue deposit.
Residual ash from the burned plant material. It carries no attributed action and is the main reason batches are chemically incomparable: the drug's identity is a location in a stove, not a species or a defined fuel.
Combustion-derived heavy metals
Heavy-metal contaminantsConcentration: Not determined and not limited. Flue soot from a stove burning coal, treated timber, painted wood or refuse rather than clean herbaceous fuel will carry the metals of that fuel.
The classical article is specified as soot from burning grasses and crop straw, but nothing in the traditional identity test distinguishes herb soot from coal soot or from the soot of a stove that has burned painted or preservative-treated wood. Coal soot in particular carries a markedly higher carcinogenic PAH fraction than biomass soot as well as arsenic and other metals.
⚠ Drug Interactions
Orally co-administered medicines in general
Carbon particles adsorb organic molecules from gut contents. The clinical benchmark is activated charcoal, where a systematic review of gastrointestinal decontamination in acute overdose found mean reductions in drug exposure of roughly 38% to 52% when charcoal was given within an hour of the drug. Soot is not activated charcoal: it has not been steam- or acid-activated and its surface area is orders of magnitude lower, so the charcoal figures are an upper bound rather than an estimate. No adsorption study has been done on Bai Cao Shuang.
Clinical note: Treat it like any adsorbent powder: do not give in the same hour as narrow-therapeutic-index oral medication. Separate by two hours.
CYP1A2 substrates (clozapine, olanzapine, theophylline)
Polycyclic aromatic hydrocarbons, not nicotine, are what makes tobacco smoke induce CYP1A1 and CYP1A2; smokers run clozapine and olanzapine concentrations roughly 40% to 50% below non-smokers, and theophylline clearance is likewise raised. Bai Cao Shuang delivers PAHs by a completely different route and at an unknown dose, and nobody has measured CYP1A2 activity after taking it, so this is an inference from the constituent class alone. It is included because the drug is knowingly a PAH-bearing material and the induction pathway is well characterised.
Clinical note: No action needed for occasional short courses. If the drug is used repeatedly in a patient on clozapine, monitor plasma concentration as you would around a change in smoking status.
Coal soot and industrial furnace soot substituted for herb soot
The drug is defined only as soot from the flue of a stove burning grass and crop straw, and no identity test in the provincial standards that carry it can distinguish that from soot generated by coal or by treated timber. Emission measurements from Chinese domestic stoves put raw bituminous coal at about an order of magnitude higher particulate PAH emission than fuel wood, with a much higher proportion of high-molecular-weight carcinogenic PAHs. As traditional straw-fired stoves have all but disappeared, the practical risk is that the substituted article is what is dispensed.
Clinical note: Do not accept undocumented soot. If the fuel and stove cannot be attested, do not dispense the drug internally.
⚠ Safety & Contraindications
Contraindications
Its use is cautious in patients with yin deficiency and internal heat.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 223–224.
Historical Texts
Bei Ji Qian Jin Yao Fang (Essential Formulas Worth a Thousand Gold for Emergencies), Sun Simiao
Tang dynasty, 652Wai Tai Mi Yao (Arcane Essentials from the Imperial Library), Wang Tao
Tang dynasty, 752Ben Cao Tu Jing (Illustrated Classic of Materia Medica), Su Song
Northern Song dynasty, 1061Ben Cao Gang Mu (Compendium of Materia Medica), Li Shizhen
Ming dynasty, 1596References
- International Agency for Research on Cancer. Soot, as Found in Occupational Exposure of Chimney Sweeps . IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 100F: Chemical Agents and Related Occupations (2012)
- Shen Guofeng, Tao Shu, Chen Yuanchen, Zhang Yanyan, Wei Siye, Xue Miao, Wang Bin, Wang Rong, Lu Yan, Li Wei, Shen Huizhong, Huang Ye, Chen Han. Emission Characteristics for Polycyclic Aromatic Hydrocarbons from Solid Fuels Burned in Domestic Stoves in Rural China . Environmental Science & Technology (2013) [DOI]
- Jenkins Bryan M., Jones A. Daniel, Turn Scott Q., Williams Robert B.. Emission Factors for Polycyclic Aromatic Hydrocarbons from Biomass Burning . Environmental Science & Technology (1996) [DOI]
- CAI Meizhen. Determination of 16 particle-phase polycyclic aromatic hydrocarbons in herbal incense by ultrasonic extraction-gas chromatography-mass spectrometry and analysis of emission characteristics . Chinese Journal of Chromatography (2022) [DOI]
- Hoegberg Lotte C. G., Shepherd Greene, Wood David M., Johnson Jami, Hoffman Robert S., Caravati E. Martin, Chan Wui Ling, Smith Silas W., Olson Kent R., Gosselin Sophie. Systematic review on the use of activated charcoal for gastrointestinal decontamination following acute oral overdose . Clinical Toxicology (2021) [DOI]
- Zevin Shoshana, Benowitz Neal L.. Drug Interactions with Tobacco Smoking . Clinical Pharmacokinetics (1999) [DOI]
- Chinese Pharmacopoeia Commission. Pharmacopoeia of the People's Republic of China, 2020 Edition, Volume I: contents list of medicinal materials and decoction pieces . China Medical Science Press (2020)
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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