Formaldehyde: An overview Treatment of Verrucae

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Formaldehyde An overview Treatment of Verrucae

• Matt Dilnot

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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

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Overview

• Formaldehyde (H2CO)
• 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 - lt 1 µg/m3 - mean 0.5 µg/m3

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WHO Average Daily Exposure

• Food 9.4 mg/d
• Inhalation 1 mg/d
• Water .15 mg/d
• Total 10.55 mg/d

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Overview

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

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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

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Formaldehyde Blood Levels
Normal Environmental Ambient 3.0 ppb (peak 8.3
ppb) .02 mg/m3
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Specific Cellular Actions

• Biocide class
• Cross-linking in the cell membrane
• Damages cell contents cross-linking
• Nucleic Acids
• Amino Acids

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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 _at_ 25 mg/m3, 6 hours a day, 5
  days a week, 2 years.
• 10-20 fold increase in cell proliferation of
  lungs.

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Carcinogenicity

• Naso-pharangeal carcinogenicity appears to be
  only risk
• Inhalation doesnt increase blood concentrations
  regardless of inhaled concentration
• Remember it is poisonous!!

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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)

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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!

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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

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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 Cant differentiate
• Dermatitis is caused only by concentrations gt 2
  Formaldehyde
• Is non-toxic to immune system

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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

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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

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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.

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Study 3Formaldehyde 10 /- MCA

• Jennings MB. Unpublished 2004. New York College.
• N46
• 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

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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

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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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