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Formaldehyde: An overview Treatment of Verrucae

Formaldehyde: An overview Treatment of Verrucae. Matt Dilnot. Conversions. 1 ppm = 1.25 mg/m3 1 mg/m3 = 0.8 ppm (at 20 °C and 1013 hPa) 1 ppb (v/v) = 1.23 mg/m3 1 µ g/m3 = 0.813 ppb (v/v) Formalin 10% = formaldehyde 28mg/mL Odour Threshold : .5 – 1.0 ppm. Overview.

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Formaldehyde: An overview Treatment of Verrucae

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  1. Formaldehyde: An overview Treatment of Verrucae Matt Dilnot

  2. Conversions • 1 ppm = 1.25 mg/m3 • 1 mg/m3 = 0.8 ppm (at 20 °C and 1013 hPa) • 1 ppb (v/v) = 1.23 mg/m3 • 1 µg/m3 = 0.813 ppb (v/v) • Formalin 10% = formaldehyde 28mg/mL • Odour Threshold : .5 – 1.0 ppm

  3. Overview • Formaldehyde (H2C=O) • Very soluble in water • Flammable, colourless, reactive and readily polymerized gas at normal room temperature and pressure • Normal part of environment e.g. Methane Cycle, decaying organic matter, forest fires • Normal part of fruit and vegetables (3-100 mg/kg) • One of the largest man made chemicals • Used in all major manufacturing industries e.g. plastics, glues, chemical reactions • Normal home – 0.014 to 0.042 mg/m3 • Natural background - < 1 µg/m3 - mean 0.5 µg/m3

  4. WHO Average Daily Exposure • Food 9.4 mg/d • Inhalation 1 mg/d • Water .15 mg/d Total: 10.55 mg/d

  5. Overview • Normal physiological substance • Endogenous formaldehyde 3-12ng/g tissue • Liver 22mg/min • Essential for protein synthesis • Normal part of Lipid Metabolism

  6. Formaldehyde Metabolism • Converted by enzymes in erythrocytes and liver • Metabolised rapidly to formate and formic acid • Formic acid oxidized to CO2 and Water • Formate is converted to sodium salt and excreted or used in biosynthesis • Liver converts 22mg/minute of formaldehyde to carbon dioxide • Intravenous infusion: half-life of 1.5 minutes

  7. Formaldehyde Blood Levels Normal Environmental Ambient ~3.0 ppb (peak 8.3 ppb) .02 mg/m3

  8. Specific Cellular Actions • Biocide class • Cross-linking in the cell membrane • Damages cell contents – cross-linking • Nucleic Acids • Amino Acids

  9. Carcinogenicity • WHO classification “probable carcinogen” • Naso-pharangeal cancer in mice and rats at high concentrations. Inhalation (18-25 mg/m3) • (Normal home – 0.014 to 0.042 mg/m3) • 900 to 1250 times normal daily exposure. Humans can only tolerate 5-6.2 mg/m3 for 30 mins. • SCCs in 50% of rats @ 25 mg/m3, 6 hours a day, 5 days a week, 2 years. • 10-20 fold increase in cell proliferation of lungs.

  10. Carcinogenicity • Naso-pharangeal carcinogenicity appears to be only risk • Inhalation doesn’t increase blood concentrations regardless of inhaled concentration Remember it is poisonous!!

  11. Cancer Epidemiology • 2 studies following ~7500 UK workers in formaldehyde factories over ~20-40 years • No cases of nasopharangeal cancer • UK death records reports 3 cases of nasopharangeal cancers in Doctors. None worked with formaldehyde (e.g. pathologists)

  12. Summary • High concentration vapours for extended periods are only reasonable risk • Exposure to normal environmental formaldehyde is safe with no measurable changes to body function/blood levels • Exposure to formalin 10% on skin is safe Formaldehyde is Poisonous!

  13. Uses in Dermatology • Hyperhidrosis – Mechanism, probable destruction of sweat glands • -cidal to most lines of cells – bacteria, fungus, viruses, skin cells. • Treatment of Burns • Verrucae • Cytotoxic to Skin • Irritates skin • Thins skin

  14. Dermal Exposure • Absorption is non-existent or negligible • Only a local effect • There is no accumulation in body or skin • Is a skin irritant and can cause allergic contact dermatitis – Can’t differentiate • Dermatitis is caused only by concentrations > 2% Formaldehyde • Is non-toxic to immune system

  15. Formalin • Commercial formaldehyde is 34.7 – 36% with buffering/diluting substances • Dilute with water e.g. 5 ml formaldehyde with 45 ml water = formalin 10% • Formalin 10% is actually ~3.47% formaldehyde • Vapours with head directly over Formalin bottle may measure up to 3mg/m3

  16. Study 1 • Vickers CFH. Treatment of plantar warts in children. Br Med J 1961; ii: 743-5 • 200 Children 6-8 weeks with 3% Formaldehyde • 80% clearance rate

  17. Study 2 • Anderson I, Shirreffs E. The treatment of Plantar Warts. Br J Dermatol 1963: 75: 29-32 • Comparison: Formaldehyde soaks v Water soaks and saccharose by mouth. • Results: No difference between groups.

  18. Study 3Formaldehyde 10% +/- MCA • Jennings MB. Unpublished 2004. New York College. • N=46 • 4 weeks formaldehyde 10% • Then divide 2 groups placebo v MCA 2 weekly (both continued formaldehyde 10%) • Once daily application for less than 20 secs. • Lazerformaldehyde® Roll-on by Pedinol • Continued for further 8 weeks • Results: Both ~75% cure rate

  19. Case Study • 23 y.o. female • Multiple Mosaic Warts, present 2 years • Treatments from 2 Pods and GP • Sal acid, Multiple Liq.Nitrogen, Wartner, Occlusion • Worked as florist, damp feet and shoes, suffers chilblains

  20. Treatment regime • Apply Formalin 10% to affected area • Apply with cotton bud for ~ 1min. • Once or twice daily • Debride once weekly with file/sand paper/pumice stone • No masking of area • Review at 4 weeks

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