ABSTRACT
The effect of continuous humidifier use on the bioaerosol concentration in an indoor environment was investigated. An ultrasonic humidifier was operated for 10 hr per day for 15 days in an apartment room. During this time period, viable bioaerosol samples were taken using a single-stage Andersen sampler containing culture media plates for bacteria and fungi. The culture plates were then incubated at room temperature for 2~7 days depending on the media. The counts for the air sample plates were corrected for multiple impactions using the positive hole conversion method and are reported as the colony forming units per cubic meter of air (CFU/m3). While the bacterial concentration measured using the tryptic soy agar (TSA) did not show any significant change during the first 3 days, the concentration increased from the 6th day (6979 CFU/m3) and reached a maximum on the 9th day (46431 CFU/m3). The concentration then decreased to 2470 CFU/m3 on the 12th day, at which point the fungal concentration increased rapidly to 14424~16038 CFU/m3. Also, while the fungal concentration showed a significant change until the 9th day of humidifier use, fungal growth was observed on the wallpaper and increased rapidly from the 12th day. However, the bacterial concentration increased rapidly after the fungi were removed by remediation. The major fungal species identified in the samples were Penicillium representing 34%, Aspergillus representing 31%, Cladosporium representing 24%, and Alternaria representing 1%. The results also indicated that a relative humidity over 80% was easily achieved with continuous humidifier use. Yet, maintaining a high humidity in a room can cause a rapid outbreak of microbial growth.
Subject(s)
Agar , Alternaria , Aspergillus , Bacteria , Cladosporium , Culture Media , Fungi , Humidity , Penicillium , Stem Cells , UltrasonicsABSTRACT
OBJECTIVES: Carbon nanotubes are an important new class of technological materials that have numerous novel and useful properties. Multi-walled carbon nanotubes (MWCNTs), which is a nanomaterial, is now in mass production because of its excellent mechanical and electrical properties. Although MWCNTs appear to have great industrial and medical potential, there is little information regarding their toxicological effects on researchers and workers who could be exposed to them by inhalation during the handling of MWCNTs. METHODS: The generation of an untangled MWCNT aerosol with a consistent concentration without using surfactants that was designed to be tested in in vivo inhalation toxicity testing was attempted. To do this, MWCNTs were dispersed in deionized water without the addition of any surfactant. To facilitate the dispersion of MWCNTs in deionized water, the water was heated to 40degrees C, 60degrees C, and 80degrees C depending on the sample with ultrasonic sonication. Then the dispersed MWCNTs were atomized to generate the MWCNT aerosol. After aerosolization of the MWCNTs, the shapes of the NTs were examined by transmission electron microscopy. RESULTS: The aerosolized MWCNTs exhibited an untangled shape and the MWCNT generation rate was about 50 mg/m3. CONCLUSION: Our method provided sufficient concentration and dispersion of MWNCTs to be used for inhalation toxicity testing.
Subject(s)
Carbon , Electrons , Handling, Psychological , Hot Temperature , Inhalation , Nanostructures , Nanotubes, Carbon , Sonication , Surface-Active Agents , Toxicity Tests , Ultrasonics , WaterABSTRACT
OBJECTIVES: The antimicrobial activity of silver nanoparticles has resulted in their widespread use in many consumer products. Yet, despite their many advantages, it is also important to determine whether silver nanoparticles may represent a hazard to the environment and human health. METHODS: Thus, to evaluate the genotoxic potential of silver nanoparticles, in vivo genotoxicity testing (OECD 474, in vivo micronuclei test) was conducted after exposing male and female Sprague-Dawley rats to silver nanoparticles by inhalation for 90 days according to OECD test guideline 413 (Subchronic Inhalation Toxicity: 90 Day Study) with a good laboratory practice system. The rats were exposed to silver nanoparticles (18 nm diameter) at concentrations of 0.7 x 10(6) particles/cm3 (low dose), 1.4 x 10(6) particles/cm3 (middle dose), and 2.9 x 10(6) particles/cm3 (high dose) for 6 hr/day in an inhalation chamber for 90 days. The rats were killed 24 hr after the last administration, then the femurs were removed and the bone marrow collected and evaluated for micronucleus induction. RESULTS: There were no statistically significant differences in the micronucleated polychromatic erythrocytes or in the ratio of polychromatic erythrocytes among the total erythrocytes after silver nanoparticle exposure when compared with the control. CONCLUSION: The present results suggest that exposure to silver nanoparticles by inhalation for 90 days does not induce genetic toxicity in male and female rat bone marrow in vivo.
Subject(s)
Animals , Female , Humans , Male , Rats , Bone Marrow , Erythrocytes , Femur , Inhalation , Inhalation Exposure , Mutagenicity Tests , Nanoparticles , Rats, Sprague-Dawley , SilverABSTRACT
OBJECTIVES: We have investigated the toxic effects of the inhalation of subchronic and acute levels of n-octane. METHODS: The rats were exposed to n-octane of 0, 2.34, 11.68 and 23.36 mg/L (n = 5 rats/group/gender) in an acute inhalation test (Organization for Economic Co-operation and Development (OECD) TG 403), or to 0, 0.93, 2.62 and 7.48 mg/L (n = 10 rats/group/gender) for a subchronic inhalation test (OECE TG 413), to establish a national chemical management system consistent with the Globally Harmonized Classification System (GHS). RESULTS: Acutely-exposed rats became lethargic but recovered following discontinuation of inhalation. Other clinical symptoms such as change of body weight and autopsy finds were absent. The LC50 for the acute inhalation toxicity of n-octane was determined to exceed 23.36 mg/L and the GHS category was 'not grouping'. Subchronically-treated rats displayed no significant clinical and histopathological differences from untreated controls; also, target organs were affected hematologically, biochemically and pathologically. Therefore, the no observable adverse effect level was indicated as exceeding 7.48 mg/L and the GHS category was 'not grouping' for the specific target organ toxicity upon repeated exposure. CONCLUSION: However, n-octane exposure should be controlled to be below the American Conference of Industrial Hygienists recommendation (300 ppm) to prevent inhalation-related adverse health effects of workers.
Subject(s)
Animals , Rats , Autopsy , Body Weight , Inhalation , OctanesABSTRACT
BACKGROUND: As in vivo models such as animal and human tests have many potential problems the keratinocyte culture model has previously been used as an in vitro model for testing skin irritancy for common skin irritants. OBJECTIVE: To determine the skin irritant potency of several solvents, we employed cultured human keratinocytes as an in vitro model. METHODS: To evaluate the cytotoxicity of solvents, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) test, lactic dehydrogenase(LDH) release test, and tritiated thymidine incorporation test were used. RESULTS: Dose dependent decrease of cell viability and DNA synthesis, and dose dependent increase in leakage of LDH liberation were observed in normal cultured human keratinocytes after exposure to several solvents. The cytotoxicity potency of several solvents measured by each method were slightly different. CONCLUSION: These observations suggest that the cultured human keratinocyte model would be useful in evaluating the cytotoxicity of solvents.
Subject(s)
Animals , Humans , Cell Survival , DNA , Irritants , Keratinocytes , Skin , Solvents , ThymidineABSTRACT
BACKGROUND: As in vivo models such as animal and human tests have many potential problems the keratinocyte culture model has previously been used as an in vitro model for testing skin irritancy for common skin irritants. OBJECTIVE: To determine the skin irritant potency of several solvents, we employed cultured human keratinocytes as an in vitro model. METHODS: To evaluate the cytotoxicity of solvents, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) test, lactic dehydrogenase(LDH) release test, and tritiated thymidine incorporation test were used. RESULTS: Dose dependent decrease of cell viability and DNA synthesis, and dose dependent increase in leakage of LDH liberation were observed in normal cultured human keratinocytes after exposure to several solvents. The cytotoxicity potency of several solvents measured by each method were slightly different. CONCLUSION: These observations suggest that the cultured human keratinocyte model would be useful in evaluating the cytotoxicity of solvents.
Subject(s)
Animals , Humans , Cell Survival , DNA , Irritants , Keratinocytes , Skin , Solvents , ThymidineABSTRACT
BACKGROUND: Solvents play an immense role in the industria sector. Irritant dermatitis which is more common than allergic contact dermatitis can be caused by solvents. OBJECTIVE: Our purpose was to compare the skin irritancy of several solvents using human and guinea pig skin models. METHODS: The skin responses to short contact with etharol, acetone, dimethylsulfoxide (DMSO) and xylene were measured by visual scoring of erythm, transepidermal water loss and laser doppler flowmetry. RESULTS: The results are summarized as follows . 1. Guinea pig and human skin responses to normal saline, ethanol, and acetone were nearly negligible. 2. Guinea pig skin responses to 99.9% DMSO under occlusion for 0.5 min were assessed by visual scoring system, TEWL, and LDF. They are measured 3+0.(0,1+21.70, 45+12.70 at 5 min after removal of 99.9% DMSQ, and 0.83+0.41, 10.5+3.83, 36+4.0, to 120 min after removal. 3. Guinea pig skin responses to 97% xylene under occlusion for 5 nin were assessed by visual scoring system, TEWL and LDF. They are measured 3+0.00, 1. 5.82, 77+11.7 at 5 min after removal of 97% xylene, and 1.83+0.75, 5.5+3.21, 39.17+11.53 at l2 min after removal. 4. Human skin responses to 75% DMSO under occlusion for 1 min were assessed by visual scoring system, TEWL and LDF. They are measured 2,5+0.5, 63+25.8, 51+13.7 at 5 min after removal of 75% DMSO, and 0.17+0.41, 14.67+15.87, 21.17-8. 1 at 120 min after removal. 5. Human skin responses to 97% xylene under occlusion for 12 min were assessed by visual scoring system, TEWL and LDF. They are measured 2.7+0.52+4.22, 76+14.30 at 5 min after removal of 97% xylene, and 0+0, 2.5+0.55, 3.17+0.98, 120 emOVBI. CONCLUSION: Short contact vrith DMSO and xylene cause visib erythema and an increase in TEWL and cutaneous blood flow. The reaction patterns in hurr an and guinea pig skin models were similar.