Genetic toxicology studies with glutaraldehyde

In vitro genotoxicity evaluation and metabolic study of residual glutaraldehyde in animal-derived biomaterials

Glutaraldehyde (GA) is an important additive that is mainly used in animal-derived biomaterials to improve their mechanical and antimicrobial capacities. However, GA chemical toxicity and the metabolic mechanism remain relatively unknown. Therefore, residual GA has always been a major health risk consideration for animal-derived medical devices. In this study, extracts of three bio-patches were tested via the GA determination test and mouse lymphoma assay (MLA). The results showed that dissolved GA was a potential mutagen, which could induce significant cytotoxic and mutagenic effects in mouse lymphoma cells. These toxic reactions were relieved by the S9 metabolic activation (MA) system. Furthermore, we confirmed that GA concentration decreased and glutaric acid was generated during the catalytic process. We revealed GA could be oxidized via cytochrome P450 which was the main metabolic factor of S9. We found that even though GA was possibly responsible for positive reactions of animal-derived biomaterials' biocompatibility evaluation, it may not represent the real situation occurring in human bodies, owing to the presence of various detoxification mechanisms including the S9 system. Overall, in order to achieve a general balance between risk management and practical application, rational decisions based on comprehensive analyses must be considered.

Glutaraldehyde exposure and its occupational impact in the health care environment

Despite the search for effective and less toxic substitutes, glutaraldehyde (GA) remains one of the few substances capable of high-level instrument disinfection in modern health care. Workers commonly affected include operating room nurses, radiographers, x-ray technicians and cleaners. Widespread hospital usage combined with its well-known irritant properties, has ensured an increase in occupationally-related illnesses during recent years. Operating room nurses, laboratory workers and x-ray technicians frequently contact GA in both the liquid and vapor form. Workplace exposure is usually dependent on job tasks, ventilation levels and the use of protective equipment. GA is a relatively potent irritant and sensitizer, with a well-documented history of symptoms following occupational exposure. Although mechanisms for GA toxicity have been postulated, research on the toxicological, teratogenic, and carcinogenic potential of this chemical has shown inconsistent results. Reducing workplace exposure to its lowest possible level represents the most important hazard reduction strategy. This may be achieved by keeping GA containers tightly sealed when not in use, maintaining adequate ventilation levels and the rigid adherence to appropriate personal protective equipment. Substitution with automated cold sterilization machines may be another appropriate measure, while banning unnecessary practices such as GA fogging and its use as a surface disinfectant may also be helpful in reducing occupational exposure in the health care environment.

The radiosensitizing potential of glutaraldehyde on MCF7 breast cancer cells as quantified by means of the G2-chromosomal radiosensitivity assay

Glutaraldehyde (GA) is a high production volume chemical that is very reactive with a wide spectrum of medical, scientific and industrial applications. Concerning the genotoxic and carcinogenic effect of GA, controversial results have been reported, while in humans no studies with positive carcinogenic results for GA have been published. However, our previous study concerning the combined effects of exposure to both GA and ionising radiation (IR) in peripheral blood lymphocytes of healthy donors has shown that non-genotoxic doses of the chemical induces a statistically significant increase in chromosomal radiosensitivity. The lack of information concerning the radiosensitizing potential of GA on cancerous cells triggered us to test the radiosensitizing effect of GA on breast cancer cells (MCF7). For this purpose the G2-chromosomal radiosensitivity assay (G2-assay) was used. The assay involves G2-phase irradiation and quantitation of the chromosomal fragility in the subsequent metaphase. The experimental data show that 48 h exposure to GA, at doses that are not clastogenic to MCF7 breast cancer cells enhances G2-chromosomal radiosensitivity of this cell line. In an effort to evaluate whether the observed increase in GAs-induced G2-chromosomal radiosensitization is linked to GA-induced alterations in the cell cycle and feedback control mechanism, Mitotic Index analysis was performed. The results have shown that such a mechanism cannot be directly related to the observed GA-induced increase in G2-chromosomal radiosensitivity. Since increased G2-chromosomal radiosensitivity has been linked with cancer proneness, the radiosensitizing effect of GA at non-clastogenic doses highlights its potential carcinogenic profile.

Laryngeal edema and metabolic acidosis after Omnicide ingestion

INTRODUCTION

Glutaraldehyde and quaternary ammonium compounds are widely used as disinfectants and sterilizing agents. Glutaraldehyde is irritating to the eyes and upper respiratory tract, and has been associated with occupational asthma. Acute oral ingestion of a concentrated solution has not been previously reported in humans.

CASE REPORT

A 19-year-old woman presented after deliberate ingestion of a biocide containing glutaraldehyde and a quaternary ammonium compound. She developed respiratory distress and severe metabolic acidosis 10 hours after admission. Marked laryngeal edema was noted when she was being intubated. She eventually improved following supportive care and was discharged alive after 9 hospital days.

DISCUSSION

There are no reports of acute ingestions of both glutaraldehyde and quaternary ammonium compounds. As both these substances are known to cause metabolic acidosis, localized edema, erosion and sensitization of both the respiratory and alimentary tract. The clinical effect may be additive or synergistic.

CONCLUSIONS

Omnicide ingestion should be closely monitored for metabolic acidosis and laryngeal edema which may progress to upper airway obstruction requiring urgent airway stabilization.

Effects of glutaraldehyde exposure on human health

Glutaraldehyde (GA) is widely used in the industrial, scientific and biomedical fields. Many adverse health effects on humans have been reported in association with biomedical uses of GA, with 2-3.5% aqueous GA solution generally used for cold sterilization and GA exposure ranges of 0.001 to 2.6 ppm for this type of use. GA is metabolized extensively to CO(2), but urinary excretion of it is low. Sensory irritant effects, sensitization of skin and respiratory organs and other symptoms have been reported among endoscopy nurses and medical radiation technologists. The prevalence of chronic bronchitis and nasal symptoms in humans is significantly correlated with peak concentrations of GA exposure. The extent of primary skin irritation depends on the duration and site of contact, and the severity of symptoms is dose-related. Chronic inhalation affects the nose and respiratory tract, and lesions become severe with prolonged duration of exposure. Increases in neither mortality nor tumor incidence have been found in workers with less than 0.2 ppm GA exposure, no evidence of carcinogenic activity has been obtained in experimental animal studies. There has been no clear evidence of genetic toxicity of GA in either in vitro or in vivo studies, and neither developmental nor reproductive toxicity has been found in humans or animals. To prevent hazards from GA exposure, use of closed-system, fully automated washing machines is recommended, since numerous symptoms have been found in individuals with less than 0.05 ppm GA exposure, the recommended peak exposure limit in many countries.

Respiratory Cancer Risks Among Workers With Glutaraldehyde Exposure

OBJECTIVE

Glutaraldehyde is a substance that represents a substantial portion of the human exposure to aldehydes in medicine and industry. Other aldehydes such as formaldehyde have been associated with increased cancer rates of the upper respiratory tract and leukemia. Our study is the only one, to our knowledge, to examine cancer rates among exposed glutaraldehyde workers.

METHODS

In an extended follow up using death certificates, we calculated standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) for three cumulative exposure categories of glutaraldehyde. There were 99,730 person-years of observation among unexposed workers, 2934 person-years in the lower exposure category, < 0-100.0 parts per billion (ppb)-years, and 2805 person-years in the higher exposure category of 100.0+ ppb-years.

RESULTS

For all respiratory cancers for these exposure categories, the SMRs were 0.9 (95% CI = 0.7-1.1), 1.0 (95% CI = 0.2-3.0), and 0.3 (95% CI = 0.0-1.5). No increasing trend of SMR with increasing exposure is observed for any cause of death examined. We observed no cancers of the nasal cavity and sinus (0.03 expected), nasopharynx (0.02 expected), or leukemia (0.6 expected) among all glutaraldehyde-exposed workers.

CONCLUSIONS

Although our study findings should be tempered by the small size and the potentially low prevalence of smoking among glutaraldehyde workers, we found no increased rates of respiratory tract cancer or leukemia related to glutaraldehyde exposure.

Ability of fourteen chemical agents used in dental practice to induce chromosome aberrations in Syrian hamster embryo cells

To assess the genotoxicity of 14 chemical agents used in dental practice, the ability of these agents to induce chromosome aberrations was examined using Syrian hamster embryo (SHE) cells. Statistically significant increases in the frequencies of chromosome aberrations were induced in SHE cells treated with 7 of 10 chemical agents used as endodontic medicaments, that is, carbol camphor, m-cresol, eugenol, guaiacol, zinc oxide, hydrogen peroxide, and formaldehyde. The other 3 chemical agents, that is, thymol, glutaraldehyde, and iodoform, did not increase the levels of chromosome aberrations. Of the 4 chemical agents that are used as an antiseptic on the oral mucosa, chromosome aberrations were induced by iodine, but not by the other 3 antiseptics, benzalkonium chloride, benzethonium chloride, and chlorhexidine. Among the 6 chemical agents exhibiting a negative response in the assay, only thymol induced chromosome aberrations in the presence of exogenous metabolic activation. Our results indicate that chemical agents having a positive response in the present study are potentially genotoxic to mammalian cells and need to be studied further in detail.

Ability of 13 chemical agents used in dental practice to induce sister-chromatid exchanges in Syrian hamster embryo cells

To evaluate the genotoxic potential of 13 chemical agents used in dental practice, the abilities of these agents to induce sister-chromatid exchanges (SCEs) were examined using Syrian hamster embryo (SHE) cells. Statistically significant increases in the frequencies of SCEs were observed in SHE cells treated with all seven of the chemical agents used as endodontic medicaments: p-chlorophenol, m-cresol, formaldehyde, guaiacol, hydrogen peroxide, p-phenolsulfonic acid, and sodium hypochlorite (P < 0.01; Student t test). Assessment of two chemical agents that are applied to the oral mucosa as antiseptics showed that SCEs were induced by iodine (P < 0.01), but not by chlorhexidine. Of three chemical agents that are used as dyes for disclosing dental plaque, erythrosine B had no effect on SCE induction, while acid fuchsin and basic fuchsin increased the SCE frequencies in SHE cells (P < 0.01). Glutaraldehyde, which is used as a disinfectant for dental instruments and impressions, also induced SCEs (P < 0.01). Because SCE assays are used as a sensitive indicator for evaluating genetic toxicity of chemicals, the chemical agents that had a positive response in the present study are potentially genotoxic to mammalian cells.

Chronic toxicity and oncogenicity study with glutaraldehyde dosed in the drinking water of Fischer 344 rats

Glutaraldehyde (GA) has a wide spectrum of industrial, scientific and biomedical applications. Its potential to produce chronic toxic and/or oncogenic effects was investigated in Fischer 344 rats (100/sex/group) given GA in drinking water for a maximum of 104 weeks. GA concentrations were 0 (control), 50,250 and 1000 ppm, resulting in average daily GA consumptions, respectively, of 0, 4, 17 and 64 mg/kg for males and 0, 6, 25 and 86 mg/kg for females. Interim euthanasia (10/sex/group) was performed at 52 and 78 weeks. Parameters evaluated were clinical signs, body weight, food and water consumption, hematology, serum chemistry, urinalysis, organ weights, gross and microscopic pathology. There were no treatment-related effects on mortality. Absolute body weights and body weight gains of the 250 and 1000 ppm males and females were reduced over the study in a dosage-related manner. Food and water consumption by the 250 and 1000 ppm groups were decreased in a statistically significant dose-related manner over the study, and mean water consumption by the 50 ppm animals was slightly reduced but not with statistical significance. The 250 and 1000 ppm groups had a dose-related decrease in urine volume with increased osmolality, and pH was slightly reduced. Absolute kidney weights were increased in the 250 and 1000 ppm groups at the 52 and 78 week sacrifices, and decreased at 104 weeks. Relative kidney weights were increased at all sacrifice times for the 1000 ppm group, at 52 weeks for the 250 ppm group, and at 72 weeks for the 50 ppm group. The urinalysis and renal weight changes are compatible with a physiological compensatory adaptation to reduced water consumption. Gross and histological evidence for gastric irritation was observed principally in the 1000 ppm rats euthanized at 104 weeks and in animals that died during the study. Bone marrow hyperplasia and renal tubular pigmentation, seen in rats that died and the 104 week euthanasia animals, may have been secondary to a low grade hemolytic anemia in animals with large granular lymphocytic leukemia (LGLL). The only neoplasm that showed a statistically significant increase was LGLL, which occurred at a high incidence in both sexes and all groups, including the controls, for both animals that died and at the 104 week euthanasia. A few instances of LGLL were observed at 78 weeks. The overall incidence of LGLL in the spleen for the 0, 50, 250 and 1000 ppm groups was, respectively, 43, 51, 40 and 46% for males, and 24, 41, 41 and 53% for females. Statistical analyses indicated that the severity of LGLL was associated with the higher dosages of GA in female, but not male, rats. Due to the background and variable incidence of LGLL in the Fischer 344 rat, the finding of a statistical significance only for female rats, and because, there was no clear dose-response relationship, the biological significance of the LGLL findings is unclear. There is the possibility that the significance was a statistical artifact due to the low incidence of LGLL in the female control animals as a result of biological variability within the study. It is also considered to be possible that the chronic dosage of GA in the drinking water resulted in a modification of one or more of the factors responsible for the expression of this common and spontaneously occurring neoplasm in the Fischer 344 rat.