[Genotoxicity of phthalates. On the discussion of plasticizers in children's toys]. / Genotoxizität von Phthalaten. Zur Diskussion über Weichmacher in Kinderspielzeug.

BACKGROUND AND OBJECTIVE: Recently, health hazards caused by phthalates, which are added as softeners to plastic materials, have been subject to discussion. The aim of the present study was to measure possible genotoxic impacts on mucosal cells of the upper aerodigestive tract. PATIENTS AND METHODS: Genotoxicity tests for dibutyl phthalate (DBP) and diisobutyl phthalate (DiBP) on human oropharyngeal mucosa in vitro were performed using the alkaline comet assay. Specimens (n = 50) were harvested from the surface of ectomized tonsils. RESULTS: DBP and DiBP caused significant DNA damage in human mucosal cells of the upper aerodigestive tract. The impact of DiBP was higher than that of DBP. CONCLUSIONS: A genotoxic impact of phthalates on human epithelial cells as a hazard to babies and children chewing these materials cannot be excluded and demands further investigation. The DNA damage measured in this study may represent one factor in the complex genesis of neoplasms in the upper aerodigestive tract.

[Cytotoxicity and genotoxicity of fluorides in human mucosa and lymphocytes]. / Zytotoxizität und Genotoxizität von Fluoriden in humaner Mukosa und Lymphozyten.

BACKGROUND: Fluorides are widely used in dental health products and drinking water, due to their beneficial effects in caries-prophylaxis and -treatment. Nevertheless, irritation of the gingiva and oropharyngeal mucosa as well as in gastric mucosa is observed since neither local nor systemic application is restricted to the teeth. These effects may partly be attributed to a known cytotoxicity of fluorides. Whether fluorides also have genotoxic effects on human mucosa or lymphocytes as a possible factor in tumor initiation was investigated in this study. MATERIAL AND METHODS: Human oropharyngeal epithelial cells and peripheral lymphocytes were incubated after single cell preparation with the aminefluoride Olaflur at concentrations of 2 ppm, 21 ppm, 35 ppm, 71 ppm and 213 ppm. The extent of cytotoxicity was investigated using the trypan blue exclusion test. Following incubation, electrophoresis for migration of DNA fragments, fluorescence staining and digital image analysis according to a standard protocol of the single cell microgel electrophoresis assay (Comet assay) followed. DNA damage was characterized using the Olive Tail Moment (OTM). RESULTS: For fluoride concentrations of 2 ppm to 35 ppm, non vital cells of less than 10% could be shown. After incubation with 71 ppm and 213 ppm Olaflur, there were 15% and 43% of damaged cells, respectively. Weak genotoxic effects on mucosal cells as well as on lymphocytes could be demonstrated at all concentrations tested. In fluoride concentrations of 213 ppm genotoxicity increased to max. OTM-levels of 23. CONCLUSIONS: Beside the cytotoxic effect of fluorides, also a minor genotoxic impact on human mucosa and on peripheral lymphocytes could be demonstrated using the Comet assay. Further investigations are warranted to examine fluorides in a model allowing for repeated or long term incubations on structurally intact human mucosa in vitro. Such a model will help to distinguish between DNA damage that may be repaired successfully and other impairments that may show an additive character in repetitive or chronic exposure in vivo.

Genotoxicity of di-butyl-phthalate and di-iso-butyl-phthalate in human lymphocytes and mucosal cells.

The genotoxicity of phthalates, widely used plasticizers, has been shown previously for di-butyl-phthalate (DBP) and di-iso-butyl-phthalate (DBP) in human mucosal cells of the upper aerodigestive tract in a previous study using the Comet assay. Furthermore, higher genotoxic sensitivities of patients with squamous cell carcinomas of either the larynx or the oropharynx compared to non-tumor patients were described. Other authors have demonstrated DNA damage by a different phthalate in human lymphocytes. It was the aim of the present study to determine whether there is a correlation between the genotoxic sensitivities to DBP and its isomer DiBP in either mucosal cells or lymphocytes. The single-cell microgel electrophoresis assay (Comet assay) was applied to detect DNA strand breaks in human epithelial cells of the upper aerodigestive tract (n=132 specimens). Human mucosa was harvested from the oropharynx in non-tumor patients and patients with squamous cell carcinomas of the oropharynx. Laryngeal mucosa of patients with laryngeal squamous cell carcinomas was harvested as well. Peripheral lymphocytes (n=49 specimens) were separated from peripheral blood. Xenobiotics investigated were DBP, DiBP, and N'methyl-N'-nitro-N-nitrosoguanidine (MNNG) as positive control, respectively. For statistical analysis, the SPSS correlation analysis according to Pearson and the Wilcoxon test were performed. Genotoxicity was found for DBP and DiBP in epithelial cells and lymphocytes (P<0.001). MNNG caused severe DNA damage. In analyzing DBP and DiBP results, genotoxic impacts in mucosal cells showed an intermediate correlation (r=0.570). Correlation in lymphocytes was the same (r=0.570). Phthalates have been investigated as a potential health hazard for a variety of reasons, including possible xenoestrogenic impact, peroxisome proliferation, and membrane destabilization. The present investigation suggests a correlated DNA-damaging impact of DBP and DiBP in human mucosal cells and in lymphocytes, respectively.

Altered genotoxicity in mucosal cells of head and neck cancer patients due to environmental pollutants.

The complexity of carcinogenesis in squamous cell cancer (SCC) of the upper aerodigestive tract requires examining environmental risk factors, including mutagen sensitivities to xenobiotics. Three environmental, occupational, and habitual pollutants - dibutylphthalate (DBP), diisobutylphthalate (DiBP), and N'nitrosodiethylamine (NDELA) - were submitted to genotoxicity testing on mucosal biopsy specimens of tumor and nontumor patients in vitro. The single-cell microgel electrophoresis (Comet) assay was applied to detect DNA strand breaks in human epithelial cells of the pharynx and larynx from nontumor patients, patients with SCC of the oropharynx and patients with SCC of the larynx. Genotoxicity was found for DBP, DiBP, and NDELA in cells derived from nontumor and tumor patients. With respect to phthalates, Olive tail moment (OTM) levels were higher in patients with SCC of the oropharynx and SCC of the larynx (P < 0.01), the latter showing even more pronounced genotoxicity for DiBP. Testing epithelial cells of the patients with either oropharyngeal or laryngeal SCC for NDELA demonstrated results similar to the nontumor patients. Present findings indicate heterogeneous mutagen sensitivities to some but not all xenobiotics.

Phthalates demonstrate genotoxicity on human mucosa of the upper aerodigestive tract.

Various phthalate compounds are used as softeners and plasticizers in a wide range of plastic materials. There has been a growing concern regarding a possible health hazard to humans. The mucosa of the upper aerodigestive tract is the organ of first contact for the majority of xenobiotics, such as phthalates, entering the body. Still, there is a lack of information concerning possible carcinogenicity of phthalates in the upper aerodigestive tract. This motivated us to investigate their genotoxic effects on human epithelia: human mucosal cells derived from biopsies harvested during surgery of the oropharynx and the inferior nasal turbinate, respectively. The alkaline version of the microgel electrophoresis assay was used to detect single-strand breaks in the DNA following incubation with dibutylphthalate (DBP) and diisobutylphthalate (DiBP). DNA damage was induced by both DBP and DiBP in oropharyngeal and nasal mucosa, though the effect of DiBP was more pronounced than that of DBP. Nasal mucosa proved to be more sensitive than oropharyngeal epithelia. The results demonstrate genotoxic effects of phthalates on human mucosal cells of the upper aerodigestive tract, in contrast to earlier findings in animal models.

[Softeners in synthetic materials--are they harmful to humans? First indication of genotoxic effect of phthalates]. / Weichmacher in Kunststoffen--gefährden sie den Menschen? Erster Hinweis auf genotoxische Wirkung von Phthalaten.

BACKGROUND: A wide range of phthalate derivatives are added to plastic materials, including PVC, as softeners. Although the possibility that these substances pose a risk to human health continues to be discussed, a definitive answer has yet to be found. In particular, their genotoxic potential has not so far been investigated in human material. METHOD: The literature is reviewed to provide an overview of the present state of such discussions. We carried out our own in vitro investigations into the genotoxicity of dibutylphthalate (DBP) and diisobutylphthalate (DIBP) in human mucosa with the aid of the alkaline version of single-cell microgel electrophoresis. RESULTS: Various effects of phthalates have been identified in the animal model, for example, changes in blood count, anti-androgenic or xenoestrogenic effects, proliferation of peroxisomes and progression of liver cell tumors. In humans, elevated phthalate levels following treatment with extracorporeal oxygenation have not been found to have any direct toxic effects. Initial results of our in vitro studies revealed a clear genotoxic potential in human oropharyngeal and nasal mucosa. CONCLUSION: Using suitable test methods, phthalates need further investigation for their health hazard potential in humans. In vitro experiments with two substances of this class involving human mucosa, indicate the possibility of geno-toxic effects.