Abstract
Ortho-Phthalaldehyde (OPA) has been approved for high-level sterilization of heat-sensitive medical instruments and is increasingly being used as a replacement in the healthcare industry for glutaraldehyde, a known sensitizer. Numerous case reports have been published indicating workers and patients experiencing respiratory problems, anaphylaxis, skin reactivity, and systemic antibody production. Our laboratory previously demonstrated that OPA is a dermal sensitizer in mice. The goal of the present study was to determine if OPA is a respiratory sensitizer following inhalation exposure. Mice were exposed to OPA vapor and airway and lymph nodes were examined for cytokine gene expression and alterations in lymphocyte populations. Inhalation of OPA for 3 days resulted in a concentration-dependent increase in lymphocyte proliferation, mainly B lymphocytes, in the draining lymph nodes. A secondary challenge of mice with OPA resulted in a dramatic increase in the population of B lymphocytes expressing IgE. Expression of Th2 (IL-4, IL-5, and IL-13) and anti/proinflammatory (IL-10, TNFα, and IL-1β) cytokine genes was upregulated in the lymph nodes and the nasal mucosa. Mice exposed to the higher concentrations of OPA-produced OPA-specific IgG1 antibodies indicating systemic sensitization. These findings provide evidence that OPA has the potential to cause respiratory sensitization in mice.
Highlights
Ortho-Phthalaldehyde (OPA) is an aromatic dialdehyde, used as a high-level antimicrobial disinfectant for medical equipment which is sensitive to normal heat or steam sterilization processes, including endoscope, cystoscopes, and certain dental instruments
In order to study the potential for the inhalation of OPA to cause respiratory sensitization, a nose-only exposure system was developed to minimize skin contact
Ortho-Phthalaldehyde has been approved by the FDA for the high-level disinfection of reusable heat sensitive medical/ dental instruments [24] and is increasingly being substituted
Summary
Ortho-Phthalaldehyde (OPA) is an aromatic dialdehyde, used as a high-level antimicrobial disinfectant for medical equipment which is sensitive to normal heat or steam sterilization processes, including endoscope, cystoscopes, and certain dental instruments. For 40 years, glutaraldehyde, another dialdehyde, has been the primary choice for disinfecting heat-sensitive medical devices; it has been reported to be a chemical sensitizer. Glutaraldehyde is known to have high affinity for biological amines, and its use as a tissue fixative capitalizes on this property. Glutaraldehyde and dialdehydes as a chemical class can bind to native proteins, altering their presentation to the immune system. Workplace exposure to glutaraldehyde is known to induce occupational asthma [2,3,4] and allergic contact dermatitis [5] suggesting the need for safer alternatives. OPA has shown superior antimycobactericidal activity as compared to glutaraldehyde [6], allowing for its use at lower concentrations. Low volatility and no need for activation have increased the use of OPA as a more practical alternative to glutaraldehyde
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