Evaluation of the respiratory tract toxicity of ortho-phthalaldehyde, a proposed alternative for the chemical disinfectant glutaraldehyde.

ortho-Phthalaldehyde (OPA) is a high-level chemical disinfectant that is commonly used for chemical sterilization of dental and medical instruments as an alternative to glutaraldehyde, a known skin and respiratory sensitizer. Concern for safe levels of human exposure remains due to a lack of toxicity data as well as human case reports of skin and respiratory sensitization following OPA exposure. The present study evaluated the inhalational toxicity of OPA in Harlan Sprague-Dawley rats and B6C3F1/N mice. Groups of 10 male and female rats and mice were exposed to OPA by whole-body inhalation for 3 months at concentrations of 0 (control), 0.44, 0.88, 1.75, 3.5, or 7.0 ppm. Rats and mice developed a spectrum of lesions at sites of contact throughout the respiratory tract (nose, larynx, trachea, lung), as well as in the skin and eye, consistent with a severe irritant response. In general, histologic lesions (necrosis, inflammation, regeneration, hyperplasia and metaplasia) occurred at deeper sites within the respiratory tract with increasing exposure concentration. As a first site of contact, the nose exhibited the greatest response to OPA exposure and resulted in an increased incidence, severity and variety of lesions compared to a previous study of glutaraldehyde exposure at similar exposure concentrations. This increased response in the nasal cavity, combined with extensive lesions throughout the respiratory tract, provides concern for use of OPA as a replacement for glutaraldehyde as a high-level disinfectant.

Comparative Cytotoxicity and Sperm Motility Using a Computer-Aided Sperm Analysis System (CASA) for Isomers of Phthalic Acid, a Common Final Metabolite of Phthalates.

The general population is exposed to phthalates through consumer products, diet, and medical devices. Phthalic acid (PA) is a common final metabolite of phthalates, and its isomers include isophthalic acid (IPA), terephthalic acid (TPA), and phthalaldehyde (o-phthalic acid, OPA). The purpose of this study was to investigate whether PA and PA isomers exert reproductive toxicity, including altered sperm movement. In vitro cell viability assays were comparatively performed using Sertoli and liver cell lines. In animal experiments, PA or PA isomers (10, 100, or 1000 mg/kg) were administered orally to Sprague-Dawley (SD) rats, and semen samples were analyzed by computer-aided sperm analysis (CASA). PA treatment produced a significant effect on curvilinear velocity (VCL), straight-line velocity (VSL), mean velocity or average path velocity (VAP), amplitude of lateral head displacement (ALH), and frequency of head displacement or beat cross-frequency (BCF), whereas IPA, TPA, and OPA induced no marked effects. In vitro cell viability assays showed that mouse normal testis cells (TM4) and human testis cancer cells (NTERA 2 cl. D1) were more sensitive to PA and OPA than mouse liver normal cells (NCTC clone 1469) and human fetal liver cells (FL 62891). Our study suggests that PA and PA isomers specifically produced significant in vitro and in vivo reproductive toxicity, particularly sperm toxicity and testis cell cytotoxicity. Of the isomers examined, PA appeared to be the most toxic and may serve as a surrogate biomarker for reproductive toxicity following mixed exposure to phthalates.

Cytotoxicity assessment of residual high-level disinfectants.

Some studies show the uptake of disinfectants on medical devices but no studies on their cytotoxicity have been reported. This study aimed to assess that cytotoxicity in a 3-dimensional culture system using HeLa cells grown in matrices composed of collagen. Plastic materials were soaked in the use solutions of the widely used high-level disinfectants, glutaraldehyde (GA), ortho-phthalaldehyde (OPA) and peracetic acid (PAA). After being rinsed, they were allowed to dry and were embedded into the cell medium to investigate the cytotoxicity of the residual disinfectants. Cytotoxicity was observed with the polyvinyl chloride, polyurethane and silicon tubes soaked in GA and OPA, indicating that both disinfectants were absorbed in the test pieces, whereas for PAA, none was observed. As for the polytetrafluoroethylene (PTFE) tubes, no disinfectant displayed cytotoxicity. GA and OPA are primary irritants, having a potential to cause anaphylaxis and other forms of allergic reactions. There should be consideration not only about the toxicity of the residual disinfectant from poor rinsing, but also about the toxicity that would result from the disinfectants that were absorbed and consequently released from the medical devices or materials.

Comparison of the cytotoxicity of high-level disinfectants by the MTT assay and direct contact assay.

Most critical instruments are not designed for heat sterilization and autoclaving. These items are usually treated with chemical agents such as peracetic acid(PAA), glutaraldehyde (GA) and ortho-phthalaldehyde (OPA). MTT assay is often used to evaluate the in vitro cytotoxicity of these chemical agents. In this study, disinfectants were allowed to come in direct contact with cells. Their cytotoxicity was evaluated based on cell viability and adhesive properties. The results obtained from the direct contact method were compared with those obtained from the conventional MTT assay wherein the disinfectants were added into a nutrient medium. It was found that the two methods yielded very different results, especially when aldehyde- and halogen-containing disinfectants were tested, and that toxicity may be underestimated in the MTT assay. Hence, it can be assumed that the direct contact assay is more accurate when evaluating the cytotoxicity of residual chemicals. It was also observed that the cytotoxicity of PAA was lower than that of GA and OPA.