CD vs Formaldehyde

Chlorine Dioxide (CD) and formaldehyde are the only effective decontaminating agents that are used for the decontamination of buildings, rooms, and bio-safety cabinets that are "true" gases. They are used because they are the only decontaminating agents that are truly effective in areas that are difficult to reach such as in floor drains, ceiling grids, the underside of components, in cabinets, hinges, and other difficult to reach areas. Other decontaminating methods such as sprays, mists, foggers, vapor generation systems, and manual wiping are not as effective because they do not reach all areas at an effective concentration.

The two processes share many similarities such as the degree of sealing required as well as the area humidification requirements and the air distribution requirements.

Today, more and more businesses are making the change and upgrading to Chlorine Dioxide. CD offers many advantages over formaldehyde such as it is non-carcinogenic, it does not require neutralization, and it leaves no residues that require manual wiping. A fully integrated chlorine dioxide monitor is available to accurately monitor and control the decontamination cycle. Additional benefits can be seen in the following table:

Attribute	Formaldehyde	Chlorine Dioxide
Safety	• Carcinogen Suspect • Exposure to Bleach or HCl may form bis-chloromethyl ether (carcinogen) • Allergen • Inhalation Hazard • Decontamination needed when exiting area • Flammable Solid • Explosive between 7 and 73% • People entering area need to be in self contained breathing apparatus (SCBA)	• Not Carcinogenic • Mucus Membrane Irritant • Inhalation can lead to pulmonary edema • No decontamination needed upon exiting facility • Potentially explosive above 10% concentration and 130°C (Generation concentration = 4%, Use concentration=0.04%) • People entering area need to be in self contained breathing apparatus (SCBA)
Current Uses	• Dialysis Sterilization (liquid) • Biological safety cabinets	• Bio-remediation (Anthrax: Hart Building, Trenton Post Office, AMI building) • Pharmaceutical and Medical Device Equipment and Components • Medical Device Sterilization • Removal of biofilms • Water Treatment • Meat • Produce • Swimming Pools
Regulatory Status	• Not registered as a fumigant	• EPA registered for pharmaceutical sterilization (including clean rooms)
Biocidal Activity	• Broad Spectrum   • High Concentration (~10.5 g/m³)   • High humidity (>70%)   • Higher temperatures (>35°C)   • Long exposure (10-12 hours) • Mixed sporicidal activity	• Broad Spectrum   • High humidity (>65%) • Good sporicidal activity
Mode of Action	• Alkylating agent	• Oxidation • Free radical monomer • Does Not Chlorinate
Chemistry	• HO-[OCH2]n-OH → CH2O(g)	• 2NaClO2 + Cl2 → 2ClO2 + 2NaCl
Functional Conditions	• Use concentrations > 50 mg/L • Concentration based on loss in mass • Need >70% RH (hydration critical to sporicidal properties) • Ideal temp > 35°C (temps between 70-80°C reduce condensation of paraformaldehyde) • Typical exposure time 10-12 hours	• Use concentrations typically 0.2 - 5 mg/L • Need >65% RH (hydration critical to sporicidal properties) • Effective at ambient temperatures (15-40°C) • In situ generation • Typical exposure time 1 hour
Disadvantages	• Must neutralize with ammonia gas generated via ammonium carbonate • Bacterial spores inoculated onto stainless steel are most resistant to decontamination • Formaldehyde has poor penetrating ability • Formaldehyde not as effective on non-porous surfaces • At the higher concentrations needed, paraformaldehyde will form a film that outgases over time • There are legal concerns over the use of paraformaldehyde as a fumigant • Cannot monitor formaldehyde concentration in real time • Need higher operating temperatures to reduce paraformaldehyde re-formation(> 35°C) • Cannot take into account loss of gas concentration due to condensation • Concern over using equipment differently than specified (fire hazard) • 15 hours at concentration • All people leaving the area must be decontaminated	• Newer technology • Can be corrosive to unpainted ferrous metals at higher concentrations
Risks	• Carcinogen • Long fumigation time • Fire due to heating of equipment • Out gassing for extended periods • Formation of bi-chlormethyl ether • Equipment Corrosion • Bleeding of paraformaldehyde into interstice and adjacent areas • Residuals can cause proteins to crosslink (amines and thiols)	• Corrosion to copper (higher concentrations > 35 mg/L) • Discoloration of urethane (high concentrations and long resonance time) • Corrosion to bare ferrous steel

Applications:

Decontamination:
Building Decontamination
Room Decontamination
Pharmaceutical Facilities
Bio-Safety Cabinets

Equipment:
Cloridox-GMP
Minidox-M
Minidox-B