Microfluidic paper-based analytical devices for simultaneous detection of oxidative potential and copper in aerosol samples.

The potential reach of point-of-care (POC) diagnostics into daily routines for exposure to reactive oxygen species (ROS) and Cu in aerosolized particulate matter (PM) demands that microfluidic paper-based analytical devices (µPADs) take into consideration the simple detection of these toxic PM components. Here, we propose µPADs with a dual-detection system for simultaneous ROS and Cu(II) detection. For colorimetric ROS detection, the glutathione (GSH) assay with a folding design to delay the reaction yielded complete ROS and GSH oxidation, and improved homogeneity of color development relative to using the lateral flow pattern. For electrochemical Cu(II) determination, 1,10-phenanthroline/Nafion modified graphene screen-printed electrodes showed ability to detect Cu(II) down to pg level being low enough to be applied to PM analysis. No intra- and inter-interference affecting both systems were found. The proposed µPADs obtained LODs for 1,4-naphthoquinone (1,4-NQ), used as the ROS representative, and Cu(II) of 8.3 ng and 3.6 pg, respectively and linear working ranges of 20 to 500 ng for ROS and 1 × 10-2 to 2 × 102 ng for Cu(II). Recovery of the method was between 81.4 and 108.3% for ROS and 80.5-105.3% for Cu(II). Finally, the sensors were utilized for simultaneous ROS and Cu(II) determination in PM samples and the results statistically agreed with those using the conventional methods at 95% confidence.

Utilization of electrocoagulation for the isolation of alkaloids from the aerial parts of Stemona aphylla and their mosquitocidal activities against Aedes aegypti.

The electrocoagulation (EC) technique is an alternative method of isolating natural products with the advantage of minimizing the amounts of organic solvents required for this process, which are often harmful to the environment. In this research, the EC and the conventional solvent extraction methods were used in the isolation of Stemona alkaloids from the aerial parts of Stemona aphylla. A comparison was made between the amounts of the isolated alkaloids and the solvents used. The isolated alkaloids were evaluated for their larvicidal, ovicidal and oviposition-deterrent activities against the dengue vector, Aedes aegypti. The morphology and histopatology of the alkaloid treated larvae were also investigated. Two Stemona alkaloids, (2'S)-hydroxystemofoline and stemofoline, were isolated from both the EC and the conventional method. The amounts of (2'S)-hydroxystemofoline from the EC method was about the same as that obtained from the conventional method. However, the amounts of stemofoline obtained from the EC method were about two times larger than those obtained from the conventional method. Importantly, the EC method required six times less total organic solvents. The larvicidal activity assays of (2'S)-hydroxystemofoline and stemofoline showed that these were highly effective against Aedes aegypti larvae with LC50 values of 3.91 µg/ml and 4.35 µg/ml, respectively. Whereas, the crude EC extract (LC50 = 11.86 µg/ml) showed greater larvicidal activity than the crude extract obtained from the conventional extraction method (LC50 = 53.40 µg/ml). The morphological observations of the (2'S)-hydroxystemofoline and the stemofoline treated larvae revealed that the anal gills were the sites of aberrations. A histopathological study showed that larvae treated with these alkaloids had cytopathological alterations to the epithelial cells of the midgut. At a concentration 40 µg/ml (2'S)-hydroxystemofoline showed 100% ovicidal activity on 24 h old eggs while stemofoline showed 97.2%. Furthermore, the oviposition-deterrent effects of (2'S)-hydroxystemofoline and stemofoline, at a concentration of 80 µg/ml were 99.5% and 97.2%, respectively.

Associations of maternal organophosphate pesticide exposure and PON1 activity with birth outcomes in SAWASDEE birth cohort, Thailand.

Prenatal organophosphate (OP) pesticide exposure has been reported to be associated with adverse birth outcomes and neurodevelopment. However, the mechanisms of toxicity of OP pesticides on human fetal development have not yet been elucidated. Our pilot study birth cohort, the Study of Asian Women and Offspring's Development and Environmental Exposures (SAWASDEE cohort) aimed to evaluate environmental chemical exposures and their relation to birth outcomes and infant neurodevelopment in 52 pregnant farmworkers in Fang district, Chiang Mai province, Thailand. A large array of data was collected multiple times during pregnancy including approximately monthly urine samples for evaluation of pesticide exposure, three blood samples for pesticide-related enzyme measurements and questionnaire data. This study investigated the changes in maternal acetylcholinesterase (AChE) and paraoxonase 1 (PON1) activities and their relation to urinary diakylphosphates (DAPs), class-related metabolites of OP pesticides, during pregnancy. Maternal AChE, butyrylcholinesterase (BChE) and PON1 activities were measured three times during pregnancy and urinary DAP concentrations were measured, on average, 8 times from enrollment during pregnancy until delivery. Among the individuals in the group with low maternal PON1 activity (n=23), newborn head circumference was negatively correlated with log10 maternal ∑DEAP and ∑DAP at enrollment (gestational age=12±3 weeks; ß=-1.0 cm, p=0.03 and ß=-1.8 cm, p<0.01, respectively) and at 32 weeks pregnancy (ß=-1.1cm, p=0.04 and ß=-2.6 cm, p=0.01, respectively). Furthermore, among these mothers, newborn birthweight was also negatively associated with log10 maternal ∑DEAP and ∑DAP at enrollment (ß=-219.7 g, p=0.05 and ß=-371.3g, p=0.02, respectively). Associations between maternal DAP levels and newborn outcomes were not observed in the group of participants with high maternal PON1 activity. Our results support previous findings from US birth cohort studies. This is the first study to report the associations between prenatal OP pesticide exposure and birth outcomes in Thailand.

Determination of the pyrethroid insecticide metabolite 3-PBA in plasma and urine samples from farmer and consumer groups in northern Thailand.

In this study, the enzyme-linked immunosorbent assays (ELISA) were modified to detect 3-PBA in plasma (including the adducted form) and urine among a large group of consumers and farmers in an agricultural area. The samples were collected on the same day in the morning from 100 consumers (50 females, 50 males) and 100 farmers (50 females, 50 males) in the Fang district, Chiang Mai province, northern Thailand. The ELISA was very sensitive having an IC50 value of 26.7 and 15.3 ng/mL, a limit of quantitation of 5 and 2.5 ng/mL and a limit of detection of 1.08 and 1.94 ng/mL for plasma and urine, respectively. These methods had low (< 5%) intra- and inter-assay coefficients of variation. The extraction technique satisfactorily eliminated the matrix effect from samples before ELISA analysis, yielding good recoveries (85.9-99.4% and 87.3-98.0%, respectively). For the volunteer study, the detection rate for plasma 3-PBA was 24% in consumers and 42% in farmers, but the median and range values were similar (median 5.87 ng/mL, range 5.16-8.44 ng/mL in consumers and 6.27 ng/mL, range 4.29-9.57 ng/mL in farmers). The rate of detection in the urine was similar (76% and 69%, in consumers and in farmers), yet the median concentration was significantly higher in farmers (8.86 µg/g creatinine in consumers vs 16.1 µg/g creatinine in farmers) and the range also much wider in farmers (1.62-80.5 µg/g creatinine in consumers and 0.80-256.2 µg/g creatinine in farmers). There was no correlation between plasma 3-PBA and urinary 3-PBA concentrations in the study presumably because plasma 3-PBA is a measure of cumulative exposures while urinary 3-PBA reflects acute exposures. In addition, metabolism and excretion of pyrethroids varies by individual. Nevertheless, this study demonstrated that these volunteers were exposed to pyrethroids. To our knowledge, this is the first report that compared plasma 3-PBA and urinary 3-PBA in a large group of volunteers. The ELISA method provided higher sample throughput with lower cost as compared to the instrumental analysis.

Polycyclic aromatic hydrocarbon removal from petroleum sludge cake using thermal treatment with additives.

Petroleum sludge is a hazardous waste that contains various organic compounds including polycyclic aromatic hydrocarbons (PAHs) which have carcinogenic-mutagenic and toxic characteristics. This study focuses on the thermal treatment (indirect heating) of petroleum sludge cake for PAH degradation at 250, 450, and 650 degrees C using Ca(OH)2 + NaHCO3 as an additive. The treatment was conducted in a rotary drum electric heater. All experiments were carried out in triplicate. Concentrations of the 16 priority PAHs in gas (absorbed on Amberlite XAD-4 adsorbent), particulate (on quartz filter) and residue phases were determined using gas chromatography-mass spectrometry (GC-MS). The samples were extracted with acetonitrile by ultra-sonication prior to GC-MS analysis. The use of additive was beneficial and a temperature of 450 degrees C was suitable for PAH degradation. Low levels of PAH emissions, particularly carcinogenic PAH and toxic equivalent concentration (sigma TEC), were observed in gas, particulate and residue phases after treatment.

Impact of Atmospheric Conditions and Source Identification of Gaseous Polycyclic Aromatic Hydrocarbons (PAHs) during a Smoke Haze Period in Upper Southeast Asia.

Gaseous polycyclic aromatic hydrocarbons were measured in northern Thailand. No previous studies have provided data on gaseous PAHs until now, so this study determined the gaseous PAHs during two sampling periods for comparison, and then they were used to assess the correlation with meteorological conditions, other pollutants, and their sources. The total concentrations of 8-PAHs (i.e., NAP, ACY, ACE, FLU, PHE, ANT, FLA, and PYR) were 125 ± 22 ng m-3 and 111 ± 21 ng m-3, with NAP being the most pronounced at 67 ± 18 ng m-3 and 56 ± 17 ng m-3, for morning and afternoon, respectively. High temperatures increase the concentrations of four-ring PAHs, whereas humidity and pressure increase the concentrations of two- and three-ring PAHs. Moreover, gaseous PAHs were estimated to contain more toxic derivatives such as nitro-PAH, which ranged from 0.02 ng m-3 (8-Nitrofluoranthene) to 10.46 ng m-3 (1-Nitronaphthalene). Therefore, they could be one of the causes of local people's health problems that have not been reported previously. Strong correlations of gaseous PAHs with ozone indicated that photochemical oxidation influenced four-ring PAHs. According to the Pearson correlation, diagnostic ratios, and principal component analysis, mixed sources including coal combustion, biomass burning, and vehicle emissions were the main sources of these pollutants.

Nitrate isotopes (δ15N, δ18O) in precipitation: best practices from an international coordinated research project.

Stable isotope ratios of nitrogen and oxygen (15N/14N and 18O/16O) of nitrate (NO3-) are excellent tracers for developing systematic understanding of sources, conversions, and deposition of reactive atmospheric nitrogen (Nr) in the environment. Despite recent analytical advances, standardized sampling of NO3-) isotopes in precipitation is still lacking. To advance atmospheric studies on Nr species, we propose best-practice guidelines for accurate and precise sampling and analysis of NO3- isotopes in precipitation based on the experience obtained from an international research project coordinated by the International Atomic Energy Agency (IAEA). The precipitation sampling and preservation strategies yielded a good agreement between the NO3- concentrations measured at the laboratories of 16 countries and at the IAEA. Compared to conventional methods (e.g., bacterial denitrification), we confirmed the accurate performance of the lower cost Ti(III) reduction method for isotope analyses (15N and 18O) of NO3- in precipitation samples. These isotopic data depict different origins and oxidation pathways of inorganic nitrogen. This work emphasized the capability of NO3- isotopes to assess the origin and atmospheric oxidation of Nr and outlined a pathway to improve laboratory capability and expertise at a global scale. The incorporation of other isotopes like 17O in Nr is recommended in future studies.

Fresh and aged PM2.5 and their ion composition in rural and urban atmospheres of Northern Thailand in relation to source identification.

This study aims to investigate ion composition of PM2.5 in various sites and seasons and to identify the main sources on spatial and temporal basis. PM2.5 compositions of two urban and two rural areas in Northern Thailand in 2019 were investigated to distinguish urban traffic and rural open burning sources. During the burning season, average PM2.5 concentrations in rural areas (104 ± 45 µg m-3) were slightly higher than those in urban areas (94 ± 39 µg m-3). Source identification of PM2.5 by cluster analysis during burning season in urban sites and one rural site revealed mixed sources of aged aerosols from biomass burning, traffic and transboundary pollution, characterized by (NH4)2SO4 and KNO3. Only PM2.5 in one rural area (Chiang Dao), where intense open burning activities observed, contained significant KCl level in addition to other compounds. KCl is being used as a tracer for fresh aerosols from biomass burning as opposes to KNO3 for aged aerosols. It was found that KNO3 proportion in total ions increased with PM2.5 concentrations both in urban and rural areas, indicating prominent open burning influences in regional scale. Source identification in other seasons was more distinguishable between urban and rural areas, and more varied depending on local emissions. Urban PM2.5 sources were secondary inorganic aerosols from traffic gas conversion in contrast with rural PM2.5 which were mainly from biomass burning.

Size-fractionated PM-bound PAHs in urban and rural atmospheres of northern Thailand for respiratory health risk assessment.

Size-fractionated particulate matters (SPMs) in a range of 9.0 to 0.43 µm, classified based on aerodynamic diameter (dae) as fine PMs (0.43 µm ≤ dae < 2.1 µm) and coarse PMs (2.1 µm ≤ dae < 9.0 µm) were collected by cascade impactors (7 fractions) during smoke haze (SH) and non-smoke haze (NSH) seasons in urban and rural areas of Chiang Mai, Thailand. Their polycyclic aromatic hydrocarbons (PAHs) compositions were determined for respiratory health risk assessment. During SH episode, concentrations of SPMs and PAHs in the rural area were approximately two times higher than in the urban area and about 62-68% of the SPMs were fine particles. Conversely, during NSH season the concentrations in the urban area were higher due to traffic emission. The finest particle sizes (0.65-0.43 µm) contained the highest PAHs concentrations among the other PM sizes. Benzo[b]fluoranthene was a main PAH component found during SH season suggesting biomass burning is a major pollutant source. High molecular weight (5-6 rings) PAHs with high carcinogenicity were likely to concentrate in fine particles. Distribution patterns of SPMs and PAHs during SH season were bimodal with the highest peak at a fine size range (0.65-0.43 µm) and a small peak at a coarse size range (5.8-4.7 µm). Respiratory health risk was estimated based on toxicity equivalent concentrations of PAHs bound-SPMs and inhalation cancer risk (ICR). Relatively high ICR values (1.14 × 10-4 (rural) and 6.80 × 10-5 (urban)) were found during SH season in both areas, in which fine particles played an important role. It revealed that high concentration of fine particles in ambient air is related to high respiratory health risk due to high content of carcinogenic substances.

Estimation of lung cancer deaths attributable to indoor radon exposure in upper northern Thailand.

Radon exposure is the second leading cause of lung cancer, after smoking. In upper northern Thailand (UNT), lung cancer incidence was frequently reported by Thailand National Cancer Institute. Besides smoking, radon exposure may also influence the high lung cancer incidence in this region. Indoor radon concentrations were measured in 192 houses in eight provinces of UNT. Indoor radon concentrations ranged from 11 to 405 Bq m-3 and estimated annual effective dose ranged from 0.44 to 12.18 mSv y-1. There were significant differences in indoor radon concentrations between the houses of lung cancer cases and healthy controls (p = 0.033). We estimated that 26% of lung cancer deaths in males and 28% in females were attributable to indoor radon exposure in this region. Other factors influencing indoor radon levels included house characteristics and ventilation. The open window-to-wall ratio was negatively associated with indoor radon levels (B = -0.69, 95% CI -1.37, -0.02) while the bedroom location in the house and building material showed no association. Indoor radon hence induced the fractal proportion of lung cancer deaths in UNT.

Characteristics and health impacts of PM2.5-bound PCDD/Fs in three Asian countries.

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) were ubiquitous, persistent chemical compounds attached to particulate matter in the atmosphere. We aimed to study the characteristics of these pollutants in atmospheric PM2.5 of three Asian countries, including Taiwan (Taipei), Thailand (Chiang Mai), and Vietnam (Hanoi). We carried out a source apportionment analysis to determine significant PCDD/F contributors in these areas. Multiple media model was conducted to access the health impact assessment. The PM2.5 concentration in Taipei (n = 7), Chiang Mai (n = 20), and Hanoi (n = 10) were 18.4 ± 6.21 µg/m3, 133 ± 49.5 µg/m3, and 88.1 ± 12.6 µg/m3, respectively. The PCDD/Fs level in Hanoi was 92.4 ± 67.3 fg I-TEQ/m3, and in Taipei and Chiang Mai was 5.01 ± 2.39 fg I-TEQ/m3 and 14.4 ± 13.1 fg I-TEQ/m3, respectively, which showed that the higher PM2.5 concentration was not necessary to follow with higher PCDD/Fs level. In all three cities, the effect of traffic on ambient PCDD/F level was significant (23-25 %). However, we also observed the specific sources of PCDD/Fs in each city during the sampling periods, namely long-range transport (Taipei, 55 %), Biomass/open burning (Chiang Mai, 77 %), and industrial activities (Hanoi, 34 %). In the carcinogenic risk estimation, the highest median total carcinogenic risk was in Hanoi (5.87 × 10-6), followed by Chiang Mai (1.06x10-6), and Taipei (2.95 × 10-7). Although diet was the major absorption pathway, the food contributor of exposure differed among the three areas due to the difference in food consumption composition.

Development of IgY-Based Indirect Competitive ELISA for the Detection of Fluoroquinolone Residues in Chicken and Pork Samples.

Fluoroquinolones (FQs) are among the antibiotics whose widespread use in farm-raised animals results in potentially harmful residues in the end products. Additionally, most Thai farmers use antibiotics. Amoxicillin and enrofloxacin were commonly used by pig farms, and hens were given enrofloxacin to prevent immunization side effects. Moreover, antibiotic overuse has harmed food safety in the long term, and the use of low-dose antibiotics causes bacterial resistance. Herein, an indirect competitive enzyme-linked immunosorbent assay (icELISA) was used to make a fast, easy, sensitive, and cost-effective method for monitoring FQs residues. After immunizing hens with mixed multi-hapten ciprofloxacin-bovine serum albumin (CPFX-BSA) with norfloxacin-bovine serum albumin (NFX-BSA), the IgY antibody purified from egg yolk was used for the detection of FQs residues in chicken and pork samples. The efficiency of the IgY antibody showed excellent sensitivity, with 50% inhibitory concentration (IC50) of enrofloxacin at 0.05 µg/mL, far below the MRLs defined by the EU for muscle samples, which was not to exceed 100 µg/kg. The recovery range for chicken muscle samples spiked with ENFX concentrations of 1.00-0.01 µg/mL was 86.65-112.71%, similar to pork samples, which were 84.24-117.22.2%. This method has a lot of potential for analyzing fluoroquinolones in complex samples quickly, easily, and at a low cost on-site. The IgY-based ic ELISA was developed to detect ciprofloxacin (CPFX), norfloxacin (NFX), and enrofloxacin (ENFX) residues; it confirms that IgY could be a promising choice for the detection of antibiotic residues in food samples.

Association between Haematological Parameters and Exposure to a Mixture of Organophosphate and Neonicotinoid Insecticides among Male Farmworkers in Northern Thailand.

Exposure to insecticides may result in various health problems. This study investigated the association between haematological parameters and exposure to a mixture of organophosphate (OP) and neonicotinoid (NEO) insecticides among male farmworkers in Fang district, Chiang Mai province, northern Thailand. Concentrations of urinary dialkylphosphates, non-specific metabolites of OPs, and NEOs and their metabolites and haematological parameters were measured in 143 male farmworkers. The Bayesian kernel machine regression model was employed to evaluate the associations. Exposure to a mixture of insecticides was significantly associated with the mean corpuscular haemoglobin concentration (MCHC) when the concentrations of all the compounds and their metabolites were at the 60th percentile or higher compared with the 50th percentile. Furthermore, exposure to clothianidin (CLO) showed a decreasing association with MCHC when all the other insecticides were at their mean concentrations. CLO was the most likely compound to reduce MCHC, and this was confirmed by sensitivity analysis. These findings suggest that exposure to NEO insecticides, especially CLO, affects the haematological status relating to haemoglobin parameters.

Exposure to Organophosphate and Neonicotinoid Insecticides and Its Association with Steroid Hormones among Male Reproductive-Age Farmworkers in Northern Thailand.

Several studies indicated organophosphate (OP) and neonicotinoid (NEO) insecticides are endocrine disruptors; however, data are scarce. This cross-sectional study recruited 143 male farmworkers aged 18-40 years in Fang district, Chiang Mai province, northern Thailand. OP exposure was assessed by measuring urinary dialkylphosphate (DAPs) using a gas-chromatography flame photometric detector. Urinary NEOs, their metabolites (NEO/m) and serum steroid hormones were measured using liquid chromatography-tandem mass spectrometry. Characteristics of participants were determined by face-to-face interviews. DAPs and five NEO/m were detected in more than 60% of samples. The concentration of diethylphosphate was highest among DAP metabolites (geometric mean concentration (GM: 23.9 ng/mL) and the concentration of imidacloprid (IMI) was highest among NEO/m (GM: 17.4 ng/mL). Linear regression models showed that the IMI level was positively associated with testosterone, dehydrocorticosterone (DHC) and dehydroepiandrosterone (DHEA) levels. Imidacloprid-olefin and DHEA levels were positively associated. Thiamethoxam (THX) were inversely associated with DHC and deoxycorticosterone levels. Clothianidin (CLO), THX and N-desmethyl-acetamiprid levels were positively associated with the androstenedione level. CLO and THX levels were inversely associated with the cortisone level. In conclusion, the association between NEO insecticides exposure and adrenal androgens, glucocorticoids and mineralocorticoids, suggest potential steroidogenesis activities. Our findings warrant further investigation.

Brown carbon light absorption over an urban environment in northern peninsular Southeast Asia.

Light-absorbing organic carbon (or brown carbon, BrC) has been recognized as a critical driver in regional-to-global climate change on account of its significant contribution to light absorption. BrC sources vary from primary combustion processes (burning of biomass, biofuel, and fossil fuel) to secondary formation in the atmosphere. This paper investigated the light-absorbing properties of BrC such as site-specific mass absorption cross-section (MACBrC), absorption Ångström exponent (AAEBrC), and the absorbing component of the refractive index (kBrC) by using light absorption measurements from a 7-wavelength aethalometer over an urban environment of Chiang Mai, Thailand in northern peninsular Southeast Asia (PSEA), from March to April 2016. The contribution of BrC to total aerosol absorption (mean ± SD) was 46 ± 9%, 29 ± 7%, 24 ± 6%, 20 ± 4%, and 15 ± 3% at 370, 470, 520, 590, and 660 nm, respectively, highlighting the significant influence of BrC absorption on the radiative imbalance over northern PSEA. Strong and significant associations between BrC light absorption and biomass-burning (BB) organic tracers highlighted the influence of primary BB emissions. The median MACBrC and kBrC values at 370 nm were 2.4 m2 g-1 and 0.12, respectively. The fractional contribution of solar radiation absorbed by BrC relative to BC (mean ± SD) in the 370-950 nm range was estimated to be 34 ± 7%, which can significantly influence the regional radiation budget and consequently atmospheric photochemistry. This study provides valuable information to understand BrC absorption over northern PSEA and can be used in model simulations to reassess the regional climatic impact with greater accuracy.

Simultaneous determination of carcinogenic PAHs and levoglucosan bound to PM2.5 for assessment of health risk and pollution sources during a smoke haze period.

Carcinogenic polycyclic aromatic hydrocarbons (cPAHs) in ambient PM2.5 and a specific molecular marker of biomass burning, levoglucosan, are used to investigate the influence on public health of biomass burning. In this work, we present an effective method for one-time analysis of cPAHs and levoglucosan by GC-MS without derivatization. The method was applied for the analysis of PM2.5 samples (64.3 ±â€¯17.6 µg m-3, n = 57) collected during a smoke haze period in Chiang Mai, Thailand. Levoglucosan was analyzed by using both the developed method (GC-MS) and a reference method (HPAEC-PAD) for comparison. Its average concentration obtained from GC-MS (0.31 ±â€¯0.21 µg m-3) was about 4 times less than the concentration obtained from the reference method (1.22 ±â€¯0.76 µg m-3). Therefore, a correcting factor (CF = 4) was used as a multiplying factor, to obtain a comparative value (1.23 ±â€¯0.86 µg m-3). The average concentration of cPAHs found in PM2.5 samples was 5.88 ±â€¯1.97 ng m-3 with the highest value of 10.86 ng m-3 indicating medium to high cancer risk due to PAHs exposure when referring to values of toxicity equivalence and inhalation cancer risk. Diagnostic ratios of BaA/(BaA + CHR) (0.48 ± 0.04) and IND/(IND + BPER) (0.58 ± 0.04) and strong correlations between PM2.5, levoglucosan and cPAHs concentrations implied that the major source of air pollution in the study period was biomass burning. PM2.5 concentration as a pollution indicator was labelled as BB-low, BB-medium, BB-high or BB-extreme; <50, 50-75, 75-100 and > 100 µg m-3, respectively. The levoglucosan and cPAHs concentration during BB-extreme pollution was 4.3 times and 2.34 times, respectively, that during BB-low pollution, and the correlation coefficient (r) between the concentrations of levoglucosan and cPAHs was as high as 0.987, indicating that the more intense the burning of biomass, the higher the carcinogenic risk in the urban air.

Development of an Immunoassay for the Detection of Amyloid Beta 1-42 and Its Application in Urine Samples.

Amyloid beta peptides (Aß1-42) have been found to be associated with the cause of Alzheimer's disease (AD) and dementia. Currently, methods for detecting Aß1-42 are complicated and expensive. The present study is aimed at developing an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) to detect Aß1-42 by using a polyclonal antibody from alpaca, an application used in urine samples. The serum was collected from the alpaca after immunizing it with Aß1-42 at 500 µg/injection 5 times. The ic-ELISA was developed and showed a half-maximal inhibitory concentration (IC50) of 103.20 ng/ml. The limit of detection (LOD) was 0.39 ng/100 µl. The cross-reactivity was tested with Aß1-40 and 8 synthesized peptides that had sequence similarities to parts of Aß1-42. The cross-reactivity of Aß1-40 and peptide 1 (DAEFRHDSGYE) was 55% and 69.4%, respectively. The ic-ELISA was applied to analyze Aß1-42 in the urine and precipitated protein urine samples. This method can be used for detecting a normal level of total soluble Aß (approximately 1 ng in 5 mg of precipitated urine protein) and can be used for detecting the early stages of AD. It is considered to be an easy and inexpensive method for monitoring and diagnosing AD.

Black carbon over an urban atmosphere in northern peninsular Southeast Asia: Characteristics, source apportionment, and associated health risks.

Black carbon (BC) has been demonstrated to pose significant negative impacts on climate and human health. Equivalent BC (EBC) measurements were conducted using a 7-wavelength aethalometer, from March to May 2016, over an urban atmosphere, viz., Chiang Mai (98.957°E, 18.795°N, 373 m above sea level), Thailand in northern peninsular Southeast Asia. Daily variations in aerosol light absorption were mainly governed by open fire activities in the region. The mean mass-specific absorption cross-section (MAC) value of EBC at 880 nm was estimated to be 9.3 m2 g-1. The median EBC mass concentration was the highest in March (3.3 µg m-3) due to biomass-burning (comprised of forest fire and agricultural burning) emissions accompanied by urban air pollution within the planetary boundary layer under favorable meteorological conditions. Daily mean absorption Ångström exponent (AAE470/950) varied between 1.3 and 1.7 and could be due to variations in EBC emission sources and atmospheric mixing processes. EBC source apportionment results revealed that biomass-burning contributed significantly more to total EBC concentrations (34-92%) as compared to fossil-fuel (traffic emissions). Health risk estimates of EBC in relation to different health outcomes were assessed in terms of passive cigarette equivalence, highlighting the considerable health effects associated with exposure to EBC levels. As a necessary action, the reduction of EBC emissions would promote considerable climate and health co-benefits.

Urinary paranitrophenol, a metabolite of methyl parathion, in Thai farmer and child populations.

Human exposure to methyl parathion can be assessed by measuring the concentration of its metabolite paranitrophenol (PNP) in urine. Our biologic monitoring study in Chiang Mai, Thailand, measured PNP and dialkylphosphate metabolites (i.e., dimethylphosphate [DMP] and dimethylthiophosphate [DMTP]) of methyl parathion in urine samples collected from 136 farmers (age 20 to 65 years) and 306 school children (age 10 to 15 years) in 2006. Participants came from two topographically different areas: one was colder and mountainous, whereas the other was alluvial with climate fluctuations depending on the monsoon season. Both children and farmers were recruited from each area. Despite methyl parathion's prohibited use in agriculture in 2004, we detected PNP in >90% of all samples analyzed. We applied a nonparametric correlation test (PNP vs. DMP and DMTP) to determine whether the PNP found in most of the samples tested resulted from exposures to methyl parathion. DMP (Spearman's rho = 0.601 [p = 0.001] for farmers and Spearman's rho = 0.263 [p <0.001] for children) and DMTP (Spearman's rho = 0.296 [p = 0.003] for farmers and Spearman's rho = 0.304 [p<0.001] for children) were positively correlated with PNP, suggesting a common source for the three analytes, presumably methyl parathion or related environmental degradates. Although we found a modest correlation between the metabolites, our findings suggest that despite the prohibition, at least a portion (approximately 25% to 60%) of the PNP detected among farmers and children in Thailand may be attributed to exposure from continued methyl parathion use.

Seasonal variation, risk assessment and source estimation of PM 10 and PM10-bound PAHs in the ambient air of Chiang Mai and Lamphun, Thailand.

Daily PM10 concentrations were measured at four sampling stations located in Chiang Mai and Lamphun provinces, Thailand. The sampling scheme was conducted during June 2005 to June 2006; every 3 days for 24 h in each sampling period. The result revealed that all stations shared the same pattern, in which the PM10 (particulate matters with diameter of less than 10 microm) concentration increased at the beginning of dry season (December) and reached its peak in March before decreasing by the end of April. The maximum PM10 concentration for each sampling station was in the range of 140-182 microg/m(3) which was 1.1-1.5 times higher than the Thai ambient air quality standard of 120 microg/m(3). This distinctly high concentration of PM10 in the dry season (Dec. 05-Mar. 06) was recognized as a unique seasonal pattern for the northern part of Thailand. PM10 concentration had a medium level of negative correlation (r = -0.696 to -0.635) with the visibility data. Comparing the maximum PM10 concentration detected at each sampling station to the permitted PM10 level of the national air quality standard, the warning visibility values for the PM10 pollution-watch system were determined as 10 km for Chiang Mai Province and 5 km for Lamphun Province. From the analysis of PM10 constituents, no component exceeded the national air quality standard. The total concentrations of PM10-bond polycyclic aromatic hydrocarbons (PAHs) are calculated in terms of total toxicity equivalent concentrations (TTECs) using the toxicity equivalent factors (TEFs) method. TTECs in Chiang Mai and Lamphun ambient air was found at a level comparable to those observed in Nagasaki, Bangkok and Rome and at a lower level than those reported at Copenhagen. The annual number of lung cancer cases for Chiang Mai and Lamphun Provinces was estimated at two cases/year which was lower than the number of cases in Bangkok (27 cases/year). The principal component analysis/absolute principal component scores (PCA/APCS) model and multiple regression analysis were applied to the PM10 and its constituents data. The results pointed to the vegetative burning as the largest PM10 contributor in Chiang Mai and Lamphun ambient air. Vegetative burning, natural gas burning & coke ovens, and secondary particle accounted for 46-82%, 12-49%, and 3-19% of the PM10 concentrations, respectively. However, natural gas burning & coke ovens as well as vehicle exhaust also deserved careful attention due to their large contributions to PAHs concentration. In the wet season and transition periods, 42-60% of the total PAHs concentrations originated from vehicle exhaust while 16-37% and 14-38% of them were apportioned to natural gas burning & coke ovens and vegetative burning, respectively. In the dry period, natural gas burning & coke ovens, vehicle exhaust, and vegetative burning accounted for 47-59%, 20-25%, and 19-28% of total PAHs concentrations. The close agreement between the measured and predicted concentrations data (R(2) > 0.8) assured enough capability of PCA/APCS receptor model to be used for the PM10 and PAHs source apportionment.