Analysis of the major factors affecting the visibility degradation in two stations.

UNLABELLED: There are four types of PM10 (particulate matter with an aerodynamic diameter <10 microm) episodes that occur frequently in central Taiwan: long-range transport with dust storms (DS), long-range transport with frontal pollution (FP), river dust (RD), and stagnant weather (SW). During the periods of the four episodes, poor visibility usually results. Multiple linear regression was applied to visibility using eight potential influential variables (temperature, relative humidity, wind speed, PM2.5, PM2.5-10, SO2, NO2, and NO) as independent variables. Of the eight variables, PM2.5 showed the greatest explainable percentage of about 48.6% and 58.1% for Taichung and Wuchi stations, respectively. This suggested that PM2.5 was the most important contributor to reduced visibility. Compared with other type of episodes, the aerosols tended to be offine size during the SWepisodes. This is the main reason that the poorest visibility occurred during the SWepisodes. Good correlation between visibility and secondary inorganic salts (NH4+, NO3, and SO4(2-)) were found at Taichung station (r = 0.71) and Wuchi station (r = 0.81), suggesting that secondary inorganic salts did contribute significantly to the degradation ofvisibility. The visibility degradation due to the effects ofNO3- was much higher than that due to SO4(2-) and NH4+ in the urban area, whereas the visibility degradation due to the effects of NO3 , SO42-, and NH4+ did not show significant diference in the rural area. IMPLICATIONS: Of the eight potential influential variables, PM2.5 showed the greatest effects on reduced visibility. Compared with other type of episodes, the aerosols tend to be fine size during the episodes of stagnant weather. This is the main reason why the poorest visibility occurred during the SW episodes. Good correlations between visibility and secondary inorganic salts (NH4+, NO3-, and SO4(2-)) suggested that secondary inorganic salts did contribute significantly to the degradation of visibility. Among the three inorganic salts, nitrates played a leading role for visibility degradation in urban areas in central Taiwan.

Comparison of polycyclic aromatic hydrocarbon emissions on gasoline- and diesel-dominated routes.

Three diesel-dominated routes (DDRs) and three gasoline-dominated routes (GDRs) were chosen as the study sites. The total number of vehicles on GDRs (47,200) was much higher than that on DDRs (14,500). The concentration of polycyclic aromatic hydrocarbons (PAHs), elemental carbon, organic carbon, and metals from GDR roadsides was higher than that for DDRs. The diagnostic ratios (ANTHR/PHE + ANTHR, FLT/FLT + PYR, BaA/BaA + CHR, and IND/IND + BghiP + ANTHN) all indicated that the major PAH source on DDR and GDR was emissions from vehicle engine combustion. The marked diesel ratios of low molecular weight PAH2.5/T-PAH2.5, methyl-PAH2.5/T-PAH2.5, methyl-PHE/PHE, and Mo/PM2.5 on DDRs were higher than those on GDRs. Significant correlations were found between the number of vehicles and the concentration of T-PAH2.5, Car-PAHs2.5, and BaPeq2.5 on DDRs and GDRs. The increase in the levels of T-PAH2.5, Car-PAHs2.5, and BaPeq2.5 per 100 vehicles on DDRs was about 3.3, 3.5, and 4.2 times higher than that on GDRs, respectively. The higher percentage of high-exhaust volume from the larger amount of diesel vehicles on DDRs than that on GDRs was the main factor leading to these results. The diagnostic ratios BaA2.5/CHR2.5 and (BbF + BkF)2.5/BghiP2.5 showed significant differences between the fine PAH sources emitted on DDRs and GDRs, whereas the diagnostic ratios Me-PAH2.5/T-PAH2.5 and (BbF + BkF)2.5/BghiP2.5 showed good correlations with the percentages of diesel exhaust volume in the total exhaust volume (E(diesel)/E(total)) on DDRs.

Aerosol characteristics of different types of episode.

Daily and hourly average data from nine air-quality monitoring stations distributed across central Taiwan, which include ten items (i.e., PM10, PM2.5, wind direction, wind speed, temperature, relative humidity, SO2, NO2, NO, and CO), were collected from 2005 to 2009. Four episode types: long-range transport with dust storms (DS), long-range transport with frontal pollution (FP), river dust (RD), and stagnant weather (SW), and one mixed type of episode were identified. Of these four episode types, the SW was the dominant type, averaging about 70%. The mean ratio of PM2.5/PM10 was the lowest during the RD episodes (0.42), while the mean ratio of PM2.5/PM10 was the highest during the SW episodes (0.64). Fine aerosol (PM2.5) and coarse aerosol (PM10-2.5) samples were collected by high-volume samplers for chemical composition analysis, from only three stations (Douliou, Lunbei, and Siansi) during the days of SW, RD, DS, and FP. The concentrations of PM2.5 and three ionic species (NH4⁺, NO3⁻, and SO4²â») all showed significant differences among the four episode types. The highest levels of NO3⁻ (12.1 µg/m(3)) and SO4²â» (20.5 µg/m(3)) were found during the SW and FP episodes, respectively. A comparison on the spatial similarity of aerosol compositions among the episodes and/or non-episodes (control) was characterized by the coefficient of divergence (CD). The results showed higher CD values in PM10-2.5 than in PM2.5, and the CD values between RD episodes and the other three episodes were higher than those between two types of episode for the other three episodes. The ratios of SOR (sulfur oxidation ratio), SO4²â»/EC (elemental carbon), NOR (nitrogen oxidation ratio), and NO3⁻/EC showed that sulfate formation was most rapid during the FP, while nitrate formation was most rapid during the SW.

Elevated risk of hypertension induced by arsenic exposure in Taiwanese rural residents: possible effects of manganese superoxide dismutase (MnSOD) and 8-oxoguanine DNA glycosylase (OGG1) genes.

Heavy metals, including arsenic and lead, may lead to cellular oxidative damage that is linked to hypertension. Manganese superoxide dismutase (MnSOD) is a scavenger of reactive oxygen species, and 8-oxoguanine DNA glycosylase (OGG1) is the major glycosylase that repairs DNA lesions. Interestingly, whether there is an elevated risk of hypertension with arsenic or lead exposure in individuals with genetic variations in MnSOD or OGG1 has not yet been investigated. Questionnaires were administered to 240 Taiwanese rural residents. Blood pressure and biochemical indicators were assessed in each subject. Urinary levels of arsenic and lead were measured with atomic absorption spectrometry; and MnSOD and OGG1 genotypes were identified via polymerase chain reaction. There was a dose-response relationship between urinary arsenic levels and risk of hypertension (P = 0.021, test for trend). However, there was no association between urinary lead levels and hypertension risk. Individuals with high urinary arsenic levels and the MnSOD Val-Ala/Ala-Ala genotypes had a greater risk of hypertension than those with low urinary arsenic levels and the MnSOD Val-Val genotype (odds ratio [OR] = 4.2, 95% confidence interval [CI] = 1.7-10.3). Subjects with a high urinary arsenic level and the OGG1 Cys-Cys genotype also had a greater risk of hypertension than those with a low urinary arsenic level and the OGG1 Ser-Ser/Ser-Cys genotypes (OR = 3.4, 95% CI = 1.1-10.7). Thus, both MnSOD and OGG1 genotypes may be prone to an increased risk of hypertension associated with arsenic exposure.

Polycyclic aromatic hydrocarbons in household dust near diesel transport routes.

A river-dredging project has been undertaken in Nantou, Taiwan. A large number of diesel vehicles carrying gravel and sand shuttle back and forth on the main roads. Ten stations along major thoroughfares were selected as the exposure sites for testing, while a small village located about 9 km from a main traffic route was selected as the control site. Levels of household dust loading at the exposure sites (60.3 mg/m(2)) were significantly higher than those at the control site (38.2 mg/m(2)). The loading (µg/m(2)) of t-PAHs (total polycyclic aromatic hydrocarbons) in the household dust at the exposure sites was significantly higher (P < 0.05) than was the case at the control site. The diagnostic ratios of PAHs showed that diesel emissions were the dominant source of PAHs at the exposure sites. The lack of a significant correlation between the concentrations of Fe and t-PAHs suggested that the t-PAHs in household dust might come from diverse sources. However, a significant correlation (P = 0.003) between the concentrations of Mo and t-PAHs implied that the most of the t-PAHs in the household dust might have resulted from diesel emissions. The lifetime cancer risks of BaP(eq) from household dust exposure were markedly higher than those resulting from inhalation exposure.

Protective equipment and health education program could benefit students from dust pollution.

In recent years, children living in the downstream of the Choshui River in Taiwan have been exposed to violent dust episodes. For the sake of the health of these children, we aimed to investigate the effectiveness of protective equipment (sand-proof plastic cover and air purifier) installed outside/inside the classrooms on students' pulmonary function and evaluate the health education program for preventing the adverse consequences of exposure to river-dust episodes. Public elementary school students in Yunlin County, which was severely affected by river-dust, were selected as the participants. Study 1 consisted of three-wave follow-up data (801 person-times) in high-/low-dust exposure regions to examine pulmonary function. Study 2 used 147 and 73 students in the high-/low-dust exposure regions, respectively, to establish our health education intervention. Paired t tests, repeated measures ANOVA, and generalized estimating equation were used to analyze the short- and long-term effects. The results showed that the students' pulmonary function in schools that installed protective equipment was improved. The health education (such as the usage of correct masks and our designed PM2.5 full-cover sand-proof clothing) improved the students' cognition and behaviors related to river-dust episodes and yielded both short- and long-term effects. Therefore, we suggest more schools with high-dust exposure to adopt protective equipment and health education program. Our designed PM2.5 full-cover sand-proof clothing can prevent from not only haze but also droplet transmission by infectious diseases such as COVID-19.

Metal exposure for residents near diesel transport routes.

For the past few years, a large number of diesel vehicles carrying gravel and sand have shuttled back and forth every day on the main route (Tai-16 and Tai-21 highways) from Shuili to Shinyi in Nantou County, Taiwan, in support of a river-dredging project. Five stations along Tai-16 and three stations along Tai-21 were selected as the exposure sites. Two very small villages located about 9 and 12 kilometers, respectively, away from the diesel transport routes were selected as the control sites. In this study, five exposure pathways, i.e., ingestion from drinking water, household dust, rice, non-rice dishes, and inhalation from airborne particles, were considered. The daily intake doses of metals varied significantly among the five exposure pathways. There was a significant difference between the exposure and control sites regarding the doses of metals obtained from the exposure pathways of household dust and aerosols. However, regarding the exposure pathways of rice, non-rice dishes, and drinking water, no significant difference between the exposure and the control sites was observed for most metals. Residents who lived within 30 meters of diesel transport roads at the exposure sites were selected as the exposure groups for urine sampling, while residents of the control sites were selected as the control groups. The metal concentrations in the urine of the exposure groups were all higher than those of the control groups. With regards to the urinary metals Fe, Pb, Cu, Ni, and Mo, the levels of urinary metals in residents and the daily intakes of metals from the five exposure pathways showed that the exposure pathways from environmental media (i.e., drinking water, aerosols, and household dust) were a greater factor than food pathways (i.e., rice and non-rice dishes) in the resulting comparative differences between urinary concentration levels of Fe, Pb, Cu, and Mo in exposure groups and control groups. However, the food exposure pathways, rather than the environmental pathways, led to greater comparative differences between the urinary concentration levels of Mn within the two groups.

Effects of diesel vehicle emissions of polycyclic aromatic hydrocarbons on the surrounding environment and residents.

Ten stations alongside major thoroughfares were selected as exposure sites, while a small village located about 3 kilometers away from a main traffic route was selected as the control site. The concentrations of particulate matters with aerodynamic less than 2.5 microm (PM(2.5)) and elemental carbon (EC) at exposure sites were both higher than those at the control site. Daytime mean concentrations of total polycyclic aromatic hydrocarbons (t-PAHs), carcinogenic PAHs (car-PAHs), and Benzo(a)pyrene-equivalent dose (BaP(eq)) at exposure sites were all about twice as high as those at the control site. A significant relationship between t-PAHs and EC was found, suggesting that most of the t-PAHs at exposure sites were contributed by diesel exhaust. Furthermore, the diagnostic ratios also show that diesel emissions were the dominant sources of PAHs at exposure sites. A multiple linear regression was applied to urinary 1-hydroxyprene (1-OHP) using four variables (exposure status, sex, smoker status, and incense burning) as independent variables. The results showed that the concentrations of 1-OHP in exposure groups were significantly (p < 0.001) higher than those in the control group. The explainable percentage for exposure status was 91.1%, indicating that the exposure factor, in comparison with other factors, has a dominant contribution to the concentration of 1-OHP. After subtracting the background levels of 1-OHP, the levels of urinary 1-OHP for residents exposed to the exhaust of 100 vehicles were about 0.062 microg/g creatinine.

Repeated measurements of urinary methylated/oxidative DNA lesions, acute toxicity, and mutagenicity in coke oven workers.

We conducted a repeated-measures cohort study of coke oven workers to evaluate the relationships between the traditional exposure biomarker, urinary 1-hydroxypyrene (1-OHP), and a series of biomarkers, including urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), N7-methylguanine (N7-MeG), acute toxicity, and mutagenicity. A total of eight spot urine samples were collected from each high-exposed (at topside oven area) and low-exposed workers (at side oven area) during the whole working cycle, which consisted of 6 consecutive days of working followed by 2 days off. Our results showed that the high-exposed workers had significantly higher urinary levels of 1-OHP, 8-oxodG, and N7-MeG compared with the low-exposed workers. Acute toxicity and mutagenicity of urine were also found to be markedly increased in the high-exposed workers, as determined by Microtox assay and Ames test, respectively. Multivariate regressions analysis revealed that the urinary 8-oxodG, N7-MeG, or acute toxicity was significantly correlated with 1-OHP concentrations. Overall, the present study showed that exposure to coke oven emissions increased oxidatively damaged DNA products and mutagenicity of urine, and for the very first time, such exposure was also found to increase DNA methylation and urinary acute toxicity. The potential source of methylating agents in coke oven emissions warrants further investigation. Additionally, with repeated measurements, the pattern of time course for urinary 1-OHP was found to be different from those of 8-oxodG and N7-MeG, as well as acute toxicity and mutagenicity. This finding implies that the single measurement that was often conducted in occupational healthy investigations should be used with certain precautions, because single measurement may fail to provide the proper information of interest.

A comparison of elementary schoolchildren's exposure to arsenic and lead.

One hundred fifty seven fifth-grade students (aged 10-12 years) from three elementary schools in three different towns in Taichung County, Taiwan were chosen as study subjects for the present arsenic and lead exposure study. The three towns--Longgang, Shalach, and Shuntain--are known to be highly, moderately, and lightly (control) polluted by As and Pb, respectively. Spot morning urine samples of students were collected and analyzed for arsenic and lead. The levels of As in the urine of Longgang schoolchildren showed the highest value among the three schools, while those of the control group (Shuntain) had the lowest values. In addition, the levels of Pb in the urine of the schoolchildren in Shuntain were significantly lower than those in Longgang and Shalach, while the levels of Pb in the urine of the schoolchildren in Longgang and Shalach showed no significant difference. Results of daily intake of metals from the different exposure pathways (i.e., ingestion from drinking water, household dust and food, and inhalation from airborne particles) showed that the Longgang area had the highest daily intake of As and Pb among the three areas, while the lowest daily intake of As and Pb occurred in the control area (Shuntain). A significant correlation between the doses of daily intake and urinary concentrations of As (p = 0.002) and Pb (p = 0.020) was observed. This correlation suggests that the increase of unit dose of the daily intake for As resulted in an increase of 0.953 microg g(-1) creatinine of As, whereas the increase of unit dose of the daily intake for Pb led to an increase of 0.053 microg g(-1) creatinine of Pb. These data indicate that the level of As in urine increased about 18 times higher than that of Pb for the same amount of increase in daily intake.

The exposure of temple workers to polycyclic aromatic hydrocarbons.

Five temples, each a different size, were selected for this study. Two of the temples were located in Taichung City (in central Taiwan), and three were in Tainan City (in Southern Taiwan). Aerosols smaller than 10 microm aerodynamic diameter (PM(10)) were collected by using personal collection samplers during pilgrim days (the first and fifteenth day of each lunar month) and normal days (all other days). Regression analysis showed that about 1.6 microg/m(3) of PM(10) contributed to the workers' exposure in the temples for each joss stick increase in the censer. The concentrations of total polycyclic aromatic hydrocarbons (t-PAHs) and carcinogenic PAHs (car-PAHs) on pilgrim days were higher than those on normal days. Mean concentrations of urinary 1-hydroxypyrene (1-OHP) in the pre-shift and post-shift workers of the five temples on normal days were 1.20 and 1.61 microg/g creatinine, respectively. Furthermore, the post-shift concentrations of 1-OHP in the workers of temples on pilgrim days were all higher than those of the workers of corresponding temples on normal days. Significant relationships between the urinary concentrations of 1-OHP and the exposure concentrations of pyrene, total PAHs and BaP(eq) were found in the workers of the temples. Results of linear regression showed that the increase of unit concentration (1 ng/m(3)) of pyrene led to a 0.05 microg/g creatinine increase of urinary 1-OHP, while the increase of unit concentration (1 ng/m(3)) of BaP(eq) resulted in an increase of 0.03 microg/g creatinine of urinary 1-OHP.

Factors affecting the concentrations of PM10 in central Taiwan.

In this study, the synoptic weather types that have high probability and low probability of producing PM10 episode are referred to as HPE and LPE, respectively. Multiple linear regressions analysis showed that NO2 was the most important contributor (35.61%) to the concentrations of PM10 for HPE weather. For LPE weather, the season factor had the greatest contribution (48.11%) to the concentrations of PM10. Using the correlation coefficients between the concentrations of PM10 and SO2 or NO2 on HPE and LPE to calculate the increase of PM10 from LPE to HPE, we found that the increase of PM10 owing to the increase of SO2 and NO2 from LPE to HPE was 12.93microg/m3 which was about 51% of the total amount of PM10 increased from LPE to HPE. Results of factor analysis showed that the first component could be attributed to the result of local pollution especially for the weather patterns of types P3 and P6, while the secondary component for the weather patterns of types P1 and P4 can be attributed to the long-range transport of SO2 pollutants from China.

Children are particularly vulnerable to environmental tobacco smoke exposure: Evidence from biomarkers of tobacco-specific nitrosamines, and oxidative stress.

BACKGROUND: Worldwide, smoking is a major public health problem, with exposure to environmental tobacco smoke (ETS) affecting both smokers, and passive smokers, including children. Despite ETS also describing secondhand, and thirdhand smoke (SHS, and THS respectively), the health effects of exposure to passive smoking via these sources are not fully understood, particularly in children. Although cotinine, the primary proximate metabolite of nicotine, has been widely used as a biomarker of ETS exposure, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), the metabolite of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), provides a uniquely important contribution, both as a biomarker of exposure, and as a specific risk indicator for pulmonary carcinogenesis. METHODS: We used LC-MS/MS to study NNK metabolites, cotinine, and 8-oxo-7,8-dihydro-2'-deoxyguanosine (a biomarker of oxidative stress), in the urine of 110 non-smoking adults (age range: 23-62) and 101 children (age range: 9-11), exposed to ETS. RESULTS: In our study of passive smoking adults, and children exposed to ETS, we showed that although the children had a similar urinary level of cotinine compared to the adults, the children had approximately two times higher levels of urinary total NNAL (P = 0.002), and free NNAL (P = 0.01), than adults. The children also had three times lower ability to detoxify NNK than adults (P < 0.001). Furthermore, the children showed 1.5 times higher ratio of total NNAL/cotinine than adults (P = 0.01), implying that THS is another important source of ETS in this population. Furthermore, ETS exposure in children appeared to lead to an increase in levels of oxidative stress. CONCLUSIONS: Taken together, our results demonstrate that, in children, THS may play an important role in the ETS exposure, and that children are at particular risk of ETS-induced health effects.

Estimation of students' exposure to metal concentrations from river-dust episodes during 1994-2012.

Two elementary schools (Shiuguang and Fongrong) from Yulin County in Taiwan, near a main area of potential exposure to Aeolian river-dust, were selected to collect outdoor and indoor PM10 aerosols and to measure five metals in PM10 (As, Ni, Cr, Cd, and Mn). Significant relationships (p < 0.01) were found between outdoor PM10 concentrations at Lunbei's air quality monitoring station and the two elementary schools. The outdoor PM10 concentrations at the monitoring station and the schools' indoor PM10 concentrations also showed significant correlations. This study also established a relationship between the outdoor and indoor concentrations of PM10 and metals in the schools. Estimations were made regarding students' 8 h of exposure to metal concentrations from river-dust episodes during 1994-2012, based on correlation equations that were shown to be statistically significant.

Increased cytochrome P4501B1 gene expression in peripheral leukocytes of municipal waste incinerator workers.

Incinerator workers are exposed to polycyclic aromatic hydrocarbons (PAHs) and dioxins in workplace. Previous studies indicated that aryl hydrocarbon receptor activation, following by increased cytochrome P4501A1 (CYP1A1) and 1B1 (CYP1B1) activity and expressions, was required for PAHs and dioxin induced toxicities. This study investigated whether municipal waste incinerator workers with frequent exposure to PAHs/dioxins in fly/bottom ash had increased CYP1A1 and CYP1B1 expressions in peripheral leukocytes and assessed whether CYP1B1*3 polymorphism modified the association between PAHs/dioxins exposure and CYP1B1 expressions. Based on job contents and time-activity profiles, 112 workers were classified into high exposure, medium exposure and control groups. CYP1A1 and CYP1B1 gene expressions in workers' leukocytes were determined with the real-time reverse transcriptase polymerase chain reaction method. After taking into account age, gender and smoking in the multiple regression analyses, CYP1B1, but not CYP1A1, levels were significantly higher in the high and medium exposure groups than in the control group, and there was a statistically significant interaction between exposure group and CYP1B1 genotype. These results suggested that CYP1B1 gene expression could be a potential biomarker of biologically effective dose for occupational exposure to PAHs/dioxins and CYP1B1*3 polymorphism modified effects of occupational exposures on CYP1B1 expression.

Accumulation of chromium and nickel metals in lung tumors from lung cancer patients in Taiwan.

Metallic carcinogenicity is generally thought to generate of free radicals, and thus some metals were reported to play a role in lung tumorigenesis. In order to verify the role of heavy metals in the development of Taiwanese lung cancer, a case-control study was conducted to compare heavy metal contents between 60 tumor and 42 normal lung tissues surgically resected from lung cancer and noncancer patients. The tissue concentration of heavy metals, including cadmium (Cd), chromium (Cr), cobalt (Co), lead (Pb), and nickel (Ni), was measured using by atomic absorption spectrometry (AAS). Our results indicated that Cr and Ni contents in lung tumors of lung cancer patients were significantly higher than those in normal lung tissue of noncancer controls, but Co content was markedly lower in lung tumors. Additionally, Pb content in lung tumors was associated with nodal involvement, and Co amounts in squamous-cell carcinomas were relatively higher than those in adenocarcinomas. Data suggest that accumulation of Cr and Ni in lung tumors may play a role, at least in part, in the development of lung cancer in Taiwan.

Emission of polycyclic aromatic hydrocarbons and lead during Chinese mid-autumn festival.

The emission factors of total particulate polycyclic aromatic hydrocarbons (PAHs), Benzo(a)pyrene (BaP), BaP-equivalent doses (BaP(eq)) and Pb for burning three kinds of charcoal were investigated in this study: fast-lighting charcoal, Taiwanese, and Indonesian charcoal (the latter two of which are not fast-lighting). Compared to the burning of Taiwanese and Indonesian charcoal, the burning of fast-lighting charcoal can emit much larger amounts of total PAHs, BaP(eq) and Pb into the atmosphere. The emission factors of total PAHs, BaP and BaP(eq) for broiling meat were noticeably higher than those for broiling vegetables and non-fish seafood. When using Indonesian charcoal to broil meat, the total emission factors of particulate PAHs and BaP were about 15.7 and 0.39 mg/kg, respectively. The total amounts of particulate PAHs and Pb emitted from cookouts during Mid-Autumn Festival were 2881 and 120 g, respectively. Total PAHs and BaP(eq) in PM(10) aerosols on Mid-Autumn Festival nights increased about 1.6 and 1.5 times, respectively, higher than those on non-festival nights. The mean concentration of Pb on the nights of Mid-Autumn Festival increases to about 2.8 times that of non-festival nights.

Variations of chemical compositions in coarse aerosols and fine aerosols in two successive episodes.

Particulate matter with diameters less than 2.5 microm (PM2.5) and ranging between 10 to 2.5 microm (PM10-2.5) were simultaneously collected at four air-quality monitoring stations in the Taichung area of central Taiwan during the period of February 12 to 22, 2004. Two different types of PM10 episodes, a nonlocal dust-storm episode and a local episode, were observed in the present study. High concentrations of coarse aerosols occurred during the dust-storm episode, whereas high concentrations of fine aerosols were present during the local episode. Relatively high levels of Na+, Mg2+, Ca2+, and Cl- in coarse aerosols were observed during the dust-storm episode. Very high concentrations of secondary aerosols (NH4+, SO4(2-), and NO3-) in fine aerosols were observed during the local episode. The nitrate ion demonstrated the greatest increase in the ratios of ionic species to PM2.5 and ionic species to PM10-2.5 during the local episode. Significantly high ratios (0.444) of NO3- to NO2 in fine aerosols were present during the local episode, indicating that the relatively high formation rate of NO3 was one of the important factors leading to the increase of the NO3 to PM2.5 ratio during the local episode. Results also showed that an abundant quantity of fine ammonium nitrate was formed during the local episode, and chloride depletion probably was the major pathway to form coarse NaNO3 during this episode.

Interaction of ciprofloxacin and probe compounds with palygorskite PFl-1.

The adsorption of ciprofloxacin (CIP) as well as probe compounds, phenylpiperazine (PP) (NH) and fluorochloroquinolone carboxylic acid (FCQCA) (COOH), on palygorskite (PFl-1) obeyed the Langmuir isotherm at pH 2, 7, and 11 except the FCQCA adsorption at pH 2. The CIP and PP adsorption onto PFl-1 was 98-160 mmol/kg. In neutral solution the total amount of exchangeable cations desorbed correlated with the adsorbed amount of CIP and PP well with a slope of 0.9-1, indicating a cation-exchange mechanism. A low amount of FCQCA adsorption of 27-57 mmol/kg was observed and the amount of exchangeable cations desorbed negatively correlate with the amount of FCQCA adsorbed as influenced by surface complexation or cation bridging. FTIR band shifting due to the ring-stretch vibration of PP and the keto-carbonyl group stretching of FCQCA suggested strong interactions as PP and FCQCA absorbed on PFl-1 in neutral solution. In the interaction of CIP with PFl-1, the piperazine-amine group played an important role in cation-exchange interaction in acidic to neutral solution, while the deprotonated keto carbonyl group actively partook in cation bridging or surface complexation with metal cations adsorbed on PFl-1 when the CIP was in anionic form in alkaline solution.

Increased levels of 8-hydroxy-2 -deoxyguanosine attributable to carcinogenic metal exposure among schoolchildren.

Arsenic, chromium, and nickel are reported in several epidemiologic studies to be associated with lung cancer. However, the health effects of arsenic, chromium, and nickel exposures are equivocal for children. Therefore, we performed a cross-sectional study to investigate possible associations between the internal concentrations of arsenic, chromium, and nickel and the level of oxidative stress to DNA in children. We measured urinary levels of arsenic, chromium, and nickel for 142 nonsmoking children using atomic absorption spectrometry. As a biomarker for oxidative stress, urinary 8-hydroxy-2 -deoxyguanosine (8-OHdG) levels were analyzed with an enzyme-linked immunosorbent assay kit. The median urinary 8-OHdG level for our subjects was 11.7 ng/mg creatinine. No obvious relationship between the levels of urinary nickel and 8-OHdG was found. Multiple linear regression analysis showed that children with higher urinary chromium had greater urinary 8-OHdG than did those with lower urinary chromium. Similarly, subjects with higher urinary arsenic had greater urinary 8-OHdG than did those with lower urinary arsenic. Furthermore, children with both high urinary arsenic and high urinary chromium had the highest 8-OHdG levels (mean +/- SE, 16.0 +/- 1.3; vs. low arsenic/low chromium, p < 0.01) in urine, followed by those with low arsenic/high chromium (13.7 +/- 1.6; vs. low arsenic/low chromium, p = 0.25), high arsenic/low chromium (12.9 +/- 1.6 vs. low arsenic/low chromium, p = 0.52), and low arsenic/low chromium (11.5 +/- 1.3); the trend was significant (p < 0.001). Thus, environmental carcinogenic metal exposure to chromium and arsenic may play an important role in oxidative DNA damage to children.