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Objectives: 1-Methylnaphthalene (1-MN) is a constituent of polycyclic aromatic hydrocarbons, the chemicals that have become ubiquitous in the environment as result of natural and industrial process. This paper reports a study on the distribution and excretion of 1-MN in rats after single and repeated inhalation exposure to 1-MN vapor.Material and Methods: Male Wistar rats were exposed to 1-MN vapor at nominal concentrations of 50 mg/m3 or 200 mg/m3 in the dynamic inhalation chambers (TSE Systems Head Nose Only Exposure) for 6 h (single exposure) or 5 days (6 h/day, repeated exposure). Blood, urine and tissue samples were collected during and after the exposure. Blood, urine and tissue concentrations of 1-MN were estimated by gas chromatography using the headspace technique.Results: The elimination of 1-MN from blood followed an open 2-compartment model. The concentration in rat tissues was dependent on the magnitude and time of exposure. After repeated exposure, the concentration 1-MN in tissue decreased in comparison to single exposure. The elimination of 1-MN with urine after single and repeated exposure to 1-MN occurred mainly in the samples collected during the first day of collection.Conclusions: 1-Methylnaphthalene was rapidly eliminated from the blood and tissues of animals exposed by inhalation to 1-MN. In repeated exposure, there was probably a significant increase of 1-MN metabolism in rats exposed to low and high 1-MN doses. Under conditions of repeated 1-MN exposure, no significant systemic 1-MN accumulation could be observed. Int J Occup Med Environ Health 2018;31(6):763-770. [ABSTRACT FROM AUTHOR]

Background: Benzalkonium chloride (BAC) is a quaternary ammonium compound (QAC) toxic to microorganisms. Inhalation is one of the major possible routes of human exposure to BAC. Materials and Methods: Experiments were performed on female Wistar rats. The rats were exposed to aerosol of BAC water solution at the target concentration of 0 (control group) and 35 mg/m for 5 days (6 h/day) and, after a 2-week interval, the animals were challenged (day 21) with BAC aerosol at the target concentration of 0 (control group) and 35 mg/m3 for 6 h. Results: Compared to the controls, the animals exposed to BAC aerosol were characterized by lower food intake and their body weight was significantly smaller. As regards BAC-exposed group, a significant increase was noted in relative lung mass, total protein concentration, and MIP-2 in BALF both directly after the termination of the exposure and 18 h afterwards. Significantly higher IL-6 and IgE concentrations in BALF and a decrease in the CC16 concentration in BALF were found in the exposed group immediately after the exposure. The leukocyte count in BALF was significantly higher in the animals exposed to BAC aerosol compared to the controls. In the lungs of rats exposed to BAC the following effects were observed: minimal perivascular, interstitial edema, focal aggregates of alveolar macrophages, interstitial mononuclear cell infiltrations, thickened alveolar septa and marginal lipoproteinosis. Conclusion: Inhalation of BAC induced a strong inflammatory response and a damage to the blood-air barrier. Reduced concentrations of CC16, which is an immunosuppressive and anti-inflammatory protein, in combination with increased IgE concentrations in BALF may be indicative of the immuno-inflammatory response in the animals exposed to BAC aerosol by inhalation. Histopathological examinations of tissue samples from the BAC-exposed rats revealed a number of pathological changes found only in the lungs. [ABSTRACT FROM AUTHOR]

Objectives: The solvent, dimethylene glycol monobutyl ether (DGBE), is a component of latex paints, inks; it is used as a degreasing agent, industrial detergent. The aim of the study was evaluating the effects of DGBE administered by gavage on the estrous cycle and given with drinking water on fertility in rats and early development of their progeny. Materials and Methods: Female rats were exposed to DGBE by gavage during 8 weeks at 250, 500 or 1000 mg/kg/day. Vaginal smears were collected during the exposure and 4 weeks after its cessation. Fertility studies were performed in male and female animals exposed to in drinking water. Males were exposed for 10 weeks and then mated with females exposed before mating, during pregnancy and lactation. Young animals were observed during 3 weeks after birth. Results: DGBE does not cause disturbances of the menstrual cycle in females. Parameters used to assess the general toxicity indicate that males receiving DGBE in drinking water are more sensitive to this compound than females: significantly greater, dose-dependent relative spleen weight, significant decrease in hematological parameters from 8% to 15% depending on the dose, were observed. Clinical chemistry parameters (HDL-cholesterol, BUN) and some markers of oxidative stress differ between the exposed groups and the control one, but without adverse health effect. The microscopic examination of internal organs did not reveal morphological changes in male and female rats. Conclusion: The results of our study on the impact of exposure to DGBE on fertility in rats indicate that the substance administered for 9-10 weeks to females and males at a limit dose of 1000 mg/kg did not impair fertility or viability of their offspring during the first three weeks of life. [ABSTRACT FROM AUTHOR]

Objectives: This paper presents toxic effects of 2-MN in laboratory animals under conditions of 4-week inhalation exposure to 2-methylnaphthalene (2-MN) vapors. Materials and Methods: Male Wistar rats were exposed to 2-MN vapors at anominal concentration of 0, 2, 10 or 50 mg/m in dynamic inhalation chambers for4 weeks (6 h/day, 5 days/week). After 4 weeks of inhalation exposure the animals were necropsied. Blood samples were collected and selected organs were weighted and prepared for histological examinations. Results: The effects of the increased levels of exposure to 2-MN experienced by the experimental rats were as follows: a) increasing γ-glutamylotransferase activity, b) stimulation of the hematopoietic system, c) lower cholesterol concentrations, d) higher number of goblet cells in lobar bronchi, e) hyperplasia of hepatic bile ducts. Conclusion: Four-week exposure of the animals to 2-MN at 2 mg/m proved to be theno-observed-adverse-effect-level (NOAEL), while 10 mg/m appeared to represent the lowest-observed-adverse-effect-level (LOAEL). [ABSTRACT FROM AUTHOR]