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1.
Environ Pollut ; 252(Pt B): 1910-1919, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31227349

RESUMO

Peroxyacetyl nitrate (PAN) is an important reservoir of atmospheric nitrogen, modulating reactive nitrogen cycle and ozone (O3) formation. To understand the origins of PAN, a field measurement was conducted at Tung Chung site (TC) in suburban Hong Kong from October to November 2016. The average level of PAN was 0.63 ±â€¯0.05 ppbv, with a maximum of 7.30 ppbv. Higher PAN/O3 ratio (0.043-0.058) was captured on episodes, i.e. when hourly maximum O3 exceeded 80 ppbv, than on non-episodes (0.01), since O3 production was less efficient than PAN when there was an elevation of precursors (i.e. volatile organic compounds (VOCs) and nitrogen oxide (NOx)). Model simulations revealed that oxidations of acetaldehyde (65.3 ±â€¯2.3%), methylglyoxal (MGLY, 12.7 ±â€¯1.2%) and other oxygenated VOCs (OVOCs) (8.0 ±â€¯0.6%), and radical cycling (12.2 ±â€¯0.8%) were the major production pathways of peroxyacetyl (PA) radical, while local PAN formation was controlled by both VOCs and nitrogen dioxide (NO2). Among all VOC species, carbonyls made the highest contribution (59%) to PAN formation, followed by aromatics (26%) and biogenic VOCs (BVOCs) (10%) through direct oxidation/decomposition. Besides, active VOCs (i.e. carbonyls, aromatics, BVOCs and alkenes/alkynes) could stimulate hydroxyl (OH) production, thus indirectly facilitating the PAN formation. Apart from primary emissions, carbonyls were also generated from oxidation of first-generation precursors, i.e., hydrocarbons, of which xylenes contributed the most to PAN production. Furthermore, PAN formation suppressed local O3 formation at a rate of 2.84 ppbv/ppbv, when NO2, OH and hydroperoxy (HO2) levels decreased and nitrogen monoxide (NO) value enhanced. Namely, O3 was reduced by 2.84 ppbv per ppbv PAN formation. Net O3 production rate was weakened (∼36%) due to PAN photochemistry, so as each individual production and loss pathway. The findings advanced our knowledge of atmospheric PAN and its impact on O3 production.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Poluição Ambiental/análise , Ozônio/análise , Ácido Peracético/análogos & derivados , Compostos Orgânicos Voláteis/análise , Acetaldeído/química , Hong Kong , Hidrocarbonetos/análise , Radical Hidroxila/análise , Óxidos de Nitrogênio/análise , Oxirredução , Ácido Peracético/análise , Fotoquímica , Aldeído Pirúvico/química , Xilenos/análise
2.
Sci Total Environ ; 685: 419-427, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31176227

RESUMO

Peracetic acid (PAA) is an emerging disinfectant with a low disinfection by-product formation potential, but how PAA destroys gene function after killing bacteria remains to be studied. Bacterial plasmid DNA is a mobile genetic element that often harbors undesirable genes encoding antibiotic resistance and virulence factors. Even though PAA efficiently kills bacteria, bacterial plasmids and other mobile genetic elements might still be intact and functional after PAA disinfection, posing potential public health and environmental risks. This study evaluated the impact of PAA disinfection on the functionality of plasmid DNA in vivo and compared the results with those from chlorination. We delivered a plasmid DNA harboring two antibiotic resistance genes to Escherichia coli TOP10 to form an antibiotic-resistant bacterium (ARB). The planktonic ARB was treated with PAA and chlorine to find the minimum doses inhibiting the regrowth of the strain. PAA and chlorine stopped the regrowth at 8 ±â€¯1 mg PAA·L-1 and 20 ±â€¯9 mg Cl2·L-1, respectively. The functionality of the plasmid DNA after PAA and chlorine disinfection was then determined at higher doses in vivo. Neither PAA nor chlorine completely destroyed the plasmid DNA. However, chlorine was more efficient than PAA in eliminating the plasmid DNA. PAA at 25 mg PAA·L-1 reduced the transforming activity of the plasmid DNA by less than 0.3 log10 units, whereas chlorine at 25 mg Cl2·L-1 reduced the transforming activity by approximately 1.7 log10 units. Chlorine had a more pronounced impact on the functionality of the plasmid DNA because it oxidizes or destroys bacterial components including plasmid DNA faster than PAA. In addition, environmental scanning electron microscopy shows that chlorination desiccated the cells resulting in the flat cellular structure and possibly more complete loss of plasmid DNA, whereas PAA disinfection had a less impact on cell structure and morphology. This study demonstrates that more plasmid DNA remains functional in water after PAA disinfection than after chlorination. These functional genetic elements could be acquired by other microorganisms via horizontal gene transfer to pose potential public health and environmental risks.


Assuntos
Desinfetantes/análise , Desinfecção/métodos , Ácido Peracético/análise , Purificação da Água/métodos , DNA Bacteriano , Halogenação , Plasmídeos/genética
3.
Environ Pollut ; 244: 379-387, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30352352

RESUMO

Peroxyacetyl nitrate (PAN) are effective indicators of photochemical pollution, and also play an important role in regional oxidant balance. Surprisingly, in recent years, PAN have also been detected under conditions that do not favor the photochemical processes. To obtain a better understanding of the mechanisms of formation of atmospheric compound pollution, this study examined the relationships between concentrations of PAN and other pollutants (e.g., ozone [O3] and PM2.5) during a winter haze episode. The observation periods were from December 31, 2015, to February 2, 2016, and from February 19, 2016, to March 4, 2016. The maximum daily concentration of PAN during haze episodes was 4-10 times higher than that during non-haze episodes. The continuous cumulative increase in PAN concentrations was the result of a combination of photochemical production during the daytime and production based on free radical chemical reactions during the nighttime. During the haze episode, the correlation between concentrations of PAN and O3 was weak, while a significant correlation was observed between PAN and PM2.5 concentrations (R2 = 0.82). This may have been due to higher concentrations of particulate matter impairing illumination, which can then inhibit the photochemical reactions that produce PAN and O3. OH radicals can replace the role of light in PAN formation, which can cause concentrations of PAN and O3 to vary independently. During the haze episode, the ratio of PAN/O3 was around 0.3, which was much higher than that during the clean period.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Poluição Ambiental/análise , Ozônio/análise , Material Particulado/análise , Ácido Peracético/análogos & derivados , Pequim , China , Radical Hidroxila/análise , Ácido Peracético/análise , Estações do Ano
4.
J Environ Sci (China) ; 77: 189-197, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30573082

RESUMO

Peroxyacyl nitrates (PANs) are important secondary pollutants in ground-level atmosphere. Accurate prediction of atmospheric pollutant concentrations is crucial to guide effective precautions for before and during specific pollution events. In this study, four models based on the back-propagation (BP) artificial neural network (ANN) and multiple linear regression (MLR) methods were used to predict the hourly average PAN concentrations at Peking University, Beijing, in 2014. The model inputs were atmospheric pollutant data and meteorological parameters. Model 3 using a BP-ANN based on the original variables achieved the best prediction results among the four models, with a correlation coefficient (R) of 0.7089, mean bias error of -0.0043 ppb, mean absolute error of 0.4836 ppb, root mean squared error of 0.5320 ppb, and Willmott's index of agreement of 0.8214. Based on a comparison of the performance indices of the MLR and BP-ANN models, we concluded that the BP-ANN model was able to capture the highly non-linear relationships between PAN concentration and the conventional atmospheric pollutant and meteorological parameters, providing more accurate results than the traditional MLR models did, with a markedly higher goodness of R. The selected meteorological and atmospheric pollutant parameters described a sufficient amount of PAN variation, and thus provided satisfactory prediction results. More specifically, the BP-ANN model performed very well for capturing the variation pattern when PAN concentrations were low. The findings of this study address some of the existing knowledge gaps in this research field and provide a theoretical basis for future regional air pollution control.


Assuntos
Monitoramento Ambiental , Ácido Peracético/análogos & derivados , Pequim , Umidade , Modelos Lineares , Material Particulado/análise , Ácido Peracético/análise , Temperatura Ambiente , Vento
5.
J Environ Sci (China) ; 71: 249-260, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30195683

RESUMO

Peroxyacetyl nitrate (PAN), as a major secondary pollutant, has gained increasing worldwide attentions, but relevant studies in China are still quite limited. During winter of 2015 to summer of 2016, the ambient levels of PAN were measured continuously by an automatic gas chromatograph equipped with an electron capture detector (GC-ECD) analyzer at an urban site in Jinan (China), with related parameters including concentrations of O3, NO, NO2, PM2.5, HONO, the photolysis rate constant of NO2 and meteorological factors observed concurrently. The mean and maximum values of PAN concentration were (1.89 ±â€¯1.42) and 9.61 ppbv respectively in winter, and (2.54 ±â€¯1.44) and 13.47 ppbv respectively in summer. Unusually high levels of PAN were observed during severe haze episodes in winter, and the formation mechanisms of them were emphatically discussed. Study showed that high levels of PAN in winter were mainly caused by local accumulation and strong photochemical reactions during haze episodes, while mass transport played only a minor role. Accelerated photochemical reactions (compared to winter days without haze) during haze episodes were deduced by the higher concentrations but shorter lifetimes of PAN, which was further supported by the sufficient solar radiation in the photolysis band along with the high concentrations of precursors (NO2, VOCs) and HONO during haze episodes. In addition, significant PAN accumulation during calm weather of haze episodes was verified by meteorological data.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Ácido Peracético/análogos & derivados , China , Conceitos Meteorológicos , Material Particulado/análise , Ácido Peracético/análise , Estações do Ano
6.
Environ Sci Pollut Res Int ; 25(23): 23143-23156, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29860696

RESUMO

Atmospheric concentrations of peroxyacetyl nitrate (PAN) were measured in Ziyang in December 2012 to provide basic knowledge of PAN in the Chengyu district and offer recommendations for air pollution management. The PAN pollution was relatively severe in Ziyang in winter, with the maximum and average PAN concentrations of 1.61 and 0.55 ppbv, respectively, and a typical single-peak diurnal trend in PAN and theoretical PAN lost by thermal decomposition (TPAN) were observed. PAN and O3 concentrations were correlated (R2 = 0.52) and the ratios of daily maximum PAN to O3 ([PAN]/[O3] ratio) ranged from 0.013 to 0.108, with an average of 0.038. Both acetone and methyl ethyl ketone (MEK) were essential for producing the acetylperoxy radicals (PA) and subsequently PAN in Ziyang in winter, and PAN concentrations at the sampling site exhibited more sensitivity to volatile organic compound (VOC) concentrations than nitrogen oxide (NOx) levels. Therefore, management should focus on reducing VOCs emissions, in particular those that produce acetone and MEK through photolysis and oxidizing reactions. In addition, the influence of relative humidity (RH) on the heterogeneous reactions between PAN and PM2.5 in the atmospheric environment may have led to the strong correlation between observed PM2.5 and PAN in Ziyang in winter. Furthermore, a typical air pollution event was observed on 17-18 December 2012, which Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) and PSCF simulations suggest that it was caused by the local formation and the regional transport of polluted air masses from Hanzhong, Nanchong, and Chengdu.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Ácido Peracético/análogos & derivados , Poluição do Ar/análise , Poluição do Ar/prevenção & controle , China , Ácido Peracético/análise , Estações do Ano
7.
Int J Occup Med Environ Health ; 31(4): 527-535, 2018 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-29411781

RESUMO

OBJECTIVES: In order to assess short-term exposure to peracetic acid (PAA) in disinfection processes, the Authors compared 4 industrial hygiene monitoring methods to evaluate their proficiency in measuring airborne PAA concentrations. MATERIAL AND METHODS: An active sampling by basic silica gel impregnated with methyl p-tolyl sulfoxide (MTSO), a passive solid phase micro-extraction technique using methyl p-tolyl sulfide (MTS) as on-fiber derivatization reagent, an electrochemical direct-reading PAA monitor, and a novel visual test strip PAA detector doped with 2,2'-azino-bis (3-ethylbenzothiazoline)-6-sulfonate were evaluated and tested over the range of 0.06-16 mg/m3, using dynamically generated PAA air concentrations. RESULTS: The linear regression analysis of linearity and accuracy showed that the 4 methods were suitable for PAA monitoring. Peracetic acid monitoring in several use applications showed that the PAA concentration (1.8 mg/m3) was immediately dangerous to life or health as proposed by the National Institute of Occupational Safety and Health, and was frequently exceeded in wastewater treatment (up to 7.33 mg/m3), and sometimes during food and beverage processes and hospital high-level disinfection operations (up to 6.8 mg/m3). CONCLUSIONS: The methods were suitable for the quick assessment of acute exposure in PAA environmental monitoring and can assist in improving safety and air quality in the workplace where this disinfectant is used. These monitoring methods allowed the evaluation of changes to work out practices to reduce PAA vapor concentrations during the operations when workers are potentially overexposed to this strong antioxidant agent. Int J Occup Med Environ Health 2018;31(4):527-535.


Assuntos
Poluentes Ocupacionais do Ar/análise , Exposição Ocupacional/análise , Ácido Peracético/análise , Desinfetantes/análise , Técnicas Eletroquímicas/métodos , Monitoramento Ambiental/métodos , Indústria de Processamento de Alimentos , Cromatografia Gasosa-Espectrometria de Massas , Hospitais , Humanos , Eliminação de Resíduos Líquidos
8.
Toxicol Ind Health ; 33(12): 922-929, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29137570

RESUMO

Peracetic acid (PAA) is a corrosive chemical with a pungent odor, which is extensively used in occupational settings and causes various health hazards in exposed workers. Currently, there is no US government agency recommended method that could be applied universally for the sampling and analysis of PAA. Legacy methods for determining airborne PAA vapor levels frequently suffered from cross-reactivity with other chemicals, particularly hydrogen peroxide (H2O2). Therefore, to remove the confounding factor of cross-reactivity, a new viable, sensitive method was developed for assessment of PAA exposure levels, based on the differential reaction kinetics of PAA with methyl p-tolylsulfide (MTS), relative to H2O2, to preferentially derive methyl p-tolysulfoxide (MTSO). By quantifying MTSO concentration produced in the liquid capture solution from an air sampler, using an internal standard, and utilizing the reaction stoichiometry of PAA and MTS, the original airborne concentration of PAA is determined. After refining this liquid trap high-performance liquid chromatography (HPLC) method in the laboratory, it was tested in five workplace settings where PAA products were used. PAA levels ranged from the detection limit of 0.013 parts per million (ppm) to 0.4 ppm. The results indicate a viable and potentially dependable method to assess the concentrations of PAA vapors under occupational exposure scenarios, though only a small number of field measurements were taken while field testing this method. However, the low limit of detection and precision offered by this method makes it a strong candidate for further testing and validation to expand the uses of this liquid trap HPLC method.


Assuntos
Poluentes Ocupacionais do Ar/análise , Monitoramento Ambiental/métodos , Ácido Peracético/análise , Cromatografia Líquida de Alta Pressão , Limite de Detecção
9.
Ann Work Expo Health ; 62(1): 28-40, 2017 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-29077798

RESUMO

Cleaning and disinfecting products consisting of a mixture of hydrogen peroxide (HP), peracetic acid (PAA), and acetic acid (AA) are widely used as sporicidal agents in health care, childcare, agricultural, food service, and food production industries. HP and PAA are strong oxidants and their mixture is a recognized asthmagen. However, few exposure assessment studies to date have measured HP, PAA, and AA in a health care setting. In 2015, we performed a health and exposure assessment at a hospital where a new sporicidal product, consisting of HP, PAA, and AA was introduced 16 months prior. We collected 49 full-shift time-weighted average (TWA) air samples and analyzed samples for HP, AA, and PAA content. Study participants were observed while they performed cleaning duties, and duration and frequency of cleaning product use was recorded. Acute upper airway, eye, and lower airway symptoms were recorded in a post-shift survey (n = 50). A subset of 35 cleaning staff also completed an extended questionnaire that assessed symptoms reported by workers as regularly occurring or as having occurred in the previous 12 months. Air samples for HP (range: 5.5 to 511.4 ppb) and AA (range: 6.7 to 530.3 ppb) were all below established US occupational exposure limits (OEL). To date, no full-shift TWA OEL for PAA has been established in the United States, however an OEL of 0.2 ppm has been suggested by several research groups. Air samples for PAA ranged from 1.1 to 48.0 ppb and were well below the suggested OEL of 0.2 ppm. Hospital cleaning staff using a sporicidal product containing HP, PAA, and AA reported work-shift eye (44%), upper airway (58%), and lower airway (34%) symptoms. Acute nasal and eye irritation were significantly positively associated with increased exposure to the mixture of the two oxidants: HP and PAA, as well as the total mixture (TM)of HP, PAA, and AA. Shortness of breath when hurrying on level ground or walking up a slight hill was significantly associated with increased exposure to the oxidant mixture (P = 0.017), as well as the TM (P = 0.026). Our results suggest that exposure to a product containing HP, PAA, and AA contributed to eye and respiratory symptoms reported by hospital cleaning staff at low levels of measured exposure.


Assuntos
Ácido Acético , Poluentes Ocupacionais do Ar , Desinfetantes , Peróxido de Hidrogênio , Exposição Ocupacional , Ácido Peracético , Recursos Humanos em Hospital/estatística & dados numéricos , Transtornos Respiratórios , Ácido Acético/análise , Ácido Acético/toxicidade , Adulto , Poluentes Ocupacionais do Ar/análise , Poluentes Ocupacionais do Ar/toxicidade , Desinfetantes/análise , Desinfetantes/toxicidade , Feminino , Humanos , Peróxido de Hidrogênio/análise , Peróxido de Hidrogênio/toxicidade , Masculino , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/análise , Ácido Peracético/análise , Ácido Peracético/toxicidade , Transtornos Respiratórios/induzido quimicamente , Transtornos Respiratórios/epidemiologia
10.
Chemosphere ; 189: 349-356, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28942261

RESUMO

Free chlorine is a commonly used disinfectant in drinking water treatment. However, disinfection by-products (DBPs) are formed during water disinfection. Haloacetic acids (HAAs) and trihalomethanes (THMs) are two major groups of DBPs. Iodo-HAAs and iodo-THMs (I-HAAs and I-THMs) are formed during the disinfection of the water containing high levels of iodide and are much more toxic than their chlorinated and brominated analogs. Peracetic acid (PAA) is a strong antimicrobial disinfectant that is expected to reduce the formation of HAAs and THMs during disinfection. In this study, the formations of thirteen HAAs and ten THMs, including the iodinated forms, have been investigated during PAA disinfection and chlorination as the comparison. The DBP formations under different iodide concentrations, pHs, and contact times were systematically investigated. Two types of commercial PAAs containing different concentrations of PAA and hydrogen peroxide (H2O2) were studied. A solid-phase microextraction gas chromatography-mass spectrometry method was upgraded for THM analysis including I-THMs. HAAs were analyzed by following a recently developed high performance ion chromatography-tandem mass spectrometry method. Results show that the ratio of PAA and H2O2 concentration significantly affect the formation of I-THMs and I-HAAs. During PAA disinfection with lower PAA than H2O2, no detectable levels of THMs and HAAs were observed. During PAA disinfection with higher PAA than H2O2, low levels of monoiodoacetic acid, diiodoacetic acid, and iodoform were formed, and these levels were enhanced with the increase of iodide concentration. No significant quantities of chloro- or bromo-THMs and HAAs were formed during PAA disinfection treatment.


Assuntos
Ácido Acético/análise , Trialometanos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Cloro/química , Desinfetantes/química , Desinfecção/métodos , Água Potável/análise , Cromatografia Gasosa-Espectrometria de Massas , Halogenação , Hidrocarbonetos Iodados , Peróxido de Hidrogênio/análise , Iodetos , Modelos Químicos , Ácido Peracético/análise
11.
Am J Infect Control ; 45(10): 1133-1138, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28549881

RESUMO

BACKGROUND: Hospital staff expressed health concerns after a surface disinfectant product containing hydrogen peroxide, peracetic acid, and acetic acid was introduced. We sought to determine if this product posed a health hazard. METHODS: An interviewer-administered questionnaire on work and health characteristics was completed by 163 current staff. Symptoms that improved away from work were considered work-related. Forty-nine air samples were taken for hydrogen peroxide, peracetic acid, and acetic acid. Prevalence ratios (PRs) were calculated using Poisson regression, and standardized morbidity ratios (SMRs) were calculated using nationally representative data. RESULTS: Product users reported higher prevalence of work-related wheeze and watery eyes than nonusers (P < .05). Workers in the department with the highest air measurements had significantly higher prevalence of watery eyes (PR, 2.88; 95% confidence interval [CI], 1.18-7.05) than those in departments with lower air measurements, and they also had a >3-fold excess of current asthma (SMR, 3.47; 95% CI, 1.48-8.13) compared with the U.S. CONCLUSIONS: This disinfectant product was associated with mucous membrane and respiratory health effects. Risks of mucous membrane irritation and asthma in health care workers should be considered in development of disinfection protocols to protect patients from hospital-acquired infections. Identification of optimal protocols that reduce worker exposures while maintaining patient safety is needed.


Assuntos
Ácido Acético/efeitos adversos , Ar/análise , Desinfetantes/efeitos adversos , Pessoal de Saúde , Peróxido de Hidrogênio/efeitos adversos , Doenças Profissionais/epidemiologia , Ácido Peracético/efeitos adversos , Ácido Acético/análise , Adolescente , Adulto , Asma/induzido quimicamente , Asma/epidemiologia , Desinfetantes/análise , Oftalmopatias/induzido quimicamente , Oftalmopatias/epidemiologia , Feminino , Hospitais , Humanos , Peróxido de Hidrogênio/análise , Masculino , Pessoa de Meia-Idade , Doenças Profissionais/induzido quimicamente , Ácido Peracético/análise , Inquéritos e Questionários , Estados Unidos/epidemiologia , Adulto Jovem
12.
Chemosphere ; 177: 339-346, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28319888

RESUMO

The interaction between photochemical oxidants and aerosol particles has been examined in previous atmospheric pollution studies. The heterogeneous reaction can affect the concentration of gases and free radicals, as well as the morphology and properties of particles. In this report, the interaction between the photochemical oxidant peroxyacetyl nitrate (PAN) and soot particles was investigated using a flow tube system. We used real-time online monitoring equipment to track changes in PAN concentrations. Substances on the soot surface were detected using ion chromatography (IC), x-ray photoelectron spectroscopy (XPS), and other surface analysis methods. At 295 K, the upper and lower limits of the initial uptake coefficients were 1.28 × 10-5 and 9.16 × 10-9, respectively. The heterogeneous reaction of PAN on soot was a first-order reaction to PAN under both dry and wet conditions. The products formed on soot included CH3COO-, HCOO-, NO2-, and NO3-. With an increase in relative humidity, the production of all species decreased and the relative amounts changed.


Assuntos
Aerossóis/análise , Oxidantes Fotoquímicos/análise , Ácido Peracético/análogos & derivados , Fuligem/análise , Cromatografia por Troca Iônica , Gases/análise , Íons , Nitrogênio/química , Ácido Peracético/análise , Espectrometria por Raios X , Temperatura Ambiente
13.
Toxicol Lett ; 233(1): 45-57, 2015 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-25542141

RESUMO

Peracetic acid (PAA) is a peroxide-based chemistry that is highly reactive and can produce strong local effects upon direct contact with the eyes, skin and respiratory tract. Given its increasing prominence in industry, attention has focused on health hazards and associated risks for PAA in the workplace. Occupational exposure limits (OEL) are one means to mitigate risks associated with chemical hazards in the workplace. A mini-review of the toxicity data for PAA was conducted in order to determine if the data were sufficient to derive health-based OELs. The available data for PAA frequently come from unpublished studies that lack sufficient study details, suffer from gaps in available information and often follow unconventional testing methodology. Despite these limitations, animal and human data suggest sensory irritation as the most sensitive endpoint associated with inhalation of PAA. Rodent RD50 data (the concentration estimated to cause a 50% depression in respiratory rate) were selected as the critical studies in deriving OELs. Based on these data, a range of 0.36-0.51mg/m(3) (0.1-0.2ppm) was calculated for a time-weighted average (TWA), and 1.2-1.7mg/m(3) (0.4-0.5ppm) as a range for a short-term exposure limit (STEL). These ranges compare favorably to other published OELs for PAA. Considering the applicable health hazards for this chemistry, a joint TWA/STEL OEL approach for PAA is deemed the most appropriate in assessing workplace exposures to PAA, and the selection of specific values within these proposed ranges represents a risk management decision.


Assuntos
Exposição Ocupacional/efeitos adversos , Ácido Peracético/toxicidade , Níveis Máximos Permitidos , Administração por Inalação , Animais , Fenômenos Químicos , Humanos , Modelos Animais , Exposição Ocupacional/análise , Ácido Peracético/análise , Saúde Pública , Testes de Toxicidade
14.
J Environ Sci (China) ; 26(10): 2007-17, 2014 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-25288544

RESUMO

Measurements of peroxyacetyl nitrate (PAN) were made at a Beijing urban site each August from 2005 to 2009. Over this 5-year period, the average PAN concentration for August in each year increased from 3 (2005) to 11.7µg/m(3) (2007); however, it decreased rapidly in 2008 (4.1µg/m(3)). Generally, the variation over the 5 years showed a rise in the first part of the study period, followed by a decline. We considered two categories of local and regional air masses in this study, which revealed that the PAN concentration in Beijing was affected mainly by southeastern air masses. The August PAN variation was influenced predominantly by local air masses in 2005, but by 2009 regional air masses had become more important. This study showed the level and variation of PAN in the month of August in 5 consecutive years for the first time, and proved that control measures are useful in decreasing photochemical pollution; hence, these measures are probably feasible for other megacities too. Furthermore, this method of analyzing regional and local impacts might be useful for other studies as well.


Assuntos
Poluentes Atmosféricos/análise , Ácido Peracético/análogos & derivados , China , Ácido Peracético/análise
15.
Environ Pollut ; 195: 39-47, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25194270

RESUMO

Peroxy acetyl nitrate (PAN) is a key component of photochemical smog and plays an important role in atmospheric chemistry. Though it has been known that PAN is produced via reactions of nitrogen oxides (NOx) with some volatile organic compounds (VOCs), it is difficult to quantify the contributions of individual precursor species. Here we use an explicit photochemical model--Master Chemical Mechanism (MCM) model--to dissect PAN formation and identify principal precursors, by analyzing measurements made in Beijing in summer 2008. PAN production was sensitive to both NOx and VOCs. Isoprene was the predominant VOC precursor at suburb with biogenic impact, whilst anthropogenic hydrocarbons dominated at downtown. PAN production was attributable to a relatively small class of compounds including NOx, xylenes, trimethylbenzenes, trans/cis-2-butenes, toluene, and propene. MCM can advance understanding of PAN photochemistry to a species level, and provide more relevant recommendations for mitigating photochemical pollution in large cities.


Assuntos
Poluentes Atmosféricos/análise , Modelos Químicos , Ácido Peracético/análogos & derivados , Compostos Orgânicos Voláteis/análise , Poluentes Atmosféricos/química , Cidades , Ácido Peracético/análise , Ácido Peracético/química , Fotoquímica , Estações do Ano , Compostos Orgânicos Voláteis/química
16.
J Sep Sci ; 37(23): 3473-80, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25250898

RESUMO

A robust method for the quantitation of epigallocatechin gallate peracetate in plasma for pharmacokinetic studies is lacking. We have developed a validated method to quantify this compound using liquid chromatography with quadrupole time-of-flight mass spectrometry with isopropanol and tert-butyl methyl ether (3:10) extraction and thin-layer chromatography purification. The epigallocatechin gallate peracetate-1-(13) C8 isotope was used as an internal standard. The linear range (r(2) > 0.9950) was from 0.05 to 100.00 µg/mL. The lower limit of quantification of the method was 0.05 µg/mL. Reproducibility, coefficient of variation, was between 0.7 and 12.6% (n = 6), accuracy between 83.7 and 104.6% (n = 5), and recovery ranged from 82.4 to 109.0% (n = 4). Ion suppression was approximately 40%. No mass spectral peaks were found to interfere between the standard and internal standard or the blank plasma extracts. Epigallocatechin gallate peracetate in plasma was stably stored at -80°C over three months even after three freeze-thaw cycles. Extracts were stable in the sampler at 4°C for over 48 h. Plasma levels were maintained at 1.36 µg/mL for 360 min after intraorbital intravenous injection at 50 mg/kg in mice. This method can be used to reliably measure epigallocatechin gallate peracetate in plasma for pharmacokinetic studies.


Assuntos
Catequina/análogos & derivados , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia em Camada Delgada/métodos , Espectrometria de Massas/métodos , Ácido Peracético/análise , Plasma/citologia , Animais , Catequina/sangue , Feminino , Camundongos , Camundongos Endogâmicos ICR , Plasma/química
17.
Sci Total Environ ; 490: 1065-72, 2014 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-24918873

RESUMO

We investigated the possibility of applying performic acid (PFA) and peracetic acid (PAA) for disinfection of combined sewer overflow (CSO) in existing CSO management infrastructures. The disinfection power of PFA and PAA towards Escherichia coli (E. coli) and Enterococcus was studied in batch-scale and pre-field experiments. In the batch-scale experiment, 2.5 mg L(-1) PAA removed approximately 4 log unit of E. coli and Enterococcus from CSO with a 360 min contact time. The removal of E. coli and Enterococcus from CSO was always around or above 3 log units using 2-4 mg L(-1) PFA; with a 20 min contact time in both batch-scale and pre-field experiments. There was no toxicological effect measured by Vibrio fischeri when CSO was disinfected with PFA; a slight toxic effect was observed on CSO disinfected with PAA. When the design for PFA based disinfection was applied to CSO collected from an authentic event, the disinfection efficiencies were confirmed and degradation rates were slightly higher than predicted in simulated CSO.


Assuntos
Desinfetantes/análise , Desinfecção/métodos , Formiatos/análise , Ácido Peracético/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/microbiologia , Poluentes Químicos da Água/análise , Drenagem Sanitária/métodos , Águas Residuárias/química , Microbiologia da Água
18.
J Environ Sci (China) ; 26(1): 65-74, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-24649692

RESUMO

Atmospheric peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), and carbon tetrachloride (CCl4) were measured from September 2010 to August 2011 in Beijing. PAN exhibited low values from mid-autumn to early spring (October to March) with monthly average concentrations ranging from 0.28 to 0.73 ppbV, and increased from early spring to summer (March to August), ranging from 1.37-3.79 ppbV. The monthly variation of PPN was similar to PAN, with low values (below detection limit to 0.18 ppbV) from mid-autumn to early spring, and a monthly maximum in September (1.14 ppbV). The monthly variation of CCl4 was tightly related to the variation of temperature, exhibiting a minimum in winter (69.3 pptV) and a maximum of 180.6 pptV in summer. Due to weak solar intensity and short duration, PAN and O3 showed no distinct diurnal patterns from morning to night during winter, whereas for other seasons, they both exhibited maximal values in the late afternoon (ca. 15:00 to 16:00 local time) and minimal values during early morning and midnight. Good linear correlations between PAN and PPN were found in autumn (R = 0.91), spring (R = 0.94), and summer (R = 0.81), with slopes of 0.130, 0.222, and 0.133, respectively, suggesting that anthropogenic hydrocarbons dominated the photochemical formation of PANs in Beijing. Positive correlation between PAN and O3 in summer with the low slopes (deltaO3/deltaPAN) ranging from 9.92 to 18.0 indicated serious air pollution in Beijing, and strong negative correlation in winter reflected strong O3 consumption by NO titration and less thermal decompositin of PAN.


Assuntos
Poluentes Atmosféricos/análise , Tetracloreto de Carbono/análise , Ozônio/análise , Ácido Peracético/análogos & derivados , Peróxidos/análise , China , Cidades , Ácido Peracético/análise , Estações do Ano
19.
J Environ Sci (China) ; 26(1): 83-96, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-24649694

RESUMO

Previous measurements of peroxyacetyl nitrate (PAN) in Asian megacities were scarce and mainly conducted for relative short periods in summer. Here, we present and analyze the measurements of PAN, O3, NO(x), etc., made at an urban site (CMA) in Beijing from 25 January to 22 March 2010. The hourly concentration of PAN averaged 0.70 x 10(-9) mol/mol (0.23 x 10(-9) -3.51 x 10(-9) mol/mol) and was well correlated with that of NO2 but not O3, indicating that the variations of the winter concentrations of PAN and 03 in urban Beijing are decoupled with each other. Wind conditions and transport of air masses exert very significant impacts on O3, PAN, and other species. Air masses arriving at the site originated either from the boundary layer over the highly polluted N-S-W sector or from the free troposphere over the W-N sector. The descending free-tropospheric air was rich in O3, with an average PAN/O3 ratio smaller than 0.031, while the boundary layer air over the polluted sector contained higher levels of PAN and primary pollutants, with an average PAN/O3 ratio of 0.11. These facts related with transport conditions can well explain the observed PAN-O3 decoupling. Photochemical production is important to PAN in the winter over Beijing. The concentration of the peroxyacetyl (PA) radical was estimated to be in the range of 0.0014 x 10(-12) -0.0042 x 10(-12) mol/mol. The contributions of the formation reaction and thermal decomposition to PAN's variation were calculated and found to be significant even in the colder period in air over Beijing, with the production exceeding the decomposition.


Assuntos
Poluentes Atmosféricos/análise , Ácido Peracético/análogos & derivados , China , Cidades , Ácido Peracético/análise , Estações do Ano , Tempo (Meteorologia)
20.
São Paulo; s.n; s.n; 2014. 132 p. tab, graf, ilus.
Tese em Inglês | LILACS | ID: biblio-847139

RESUMO

O colesterol é um importante componente das membranas celulares em eucariotos superiores, desempenhando papéis estruturais e funcionais. O colesterol possui uma insaturação em sua estrutura sendo, portanto, alvo de oxidação mediada por espécies reativas de oxigênio e/ou nitrogênio. A oxidação não enzimática do colesterol gera, como produtos primários, os hidroperóxidos de colesterol. Tais moléculas, por sua vez, são altamente reativas e podem reagir com metais livres e/ou metaloproteínas, trazendo consequências à celula. Neste sentido, o primeiro capítulo deste trabalho tem como objetivo estudar a reação dos hidroperóxidos de colesterol (ChOOH) com o citocromo c (citc), uma heme proteína envolvida no transporte de elétrons na mitocôndria. Análises de espectroscopia no UV-Vis mostraram que o ChOOH promove o bleaching da banda Soret do citc de uma maneira dose-dependente. Mais ainda, esta reação leva à formação de radicais centrados em carbono tanto na proteína como no lipídeo, sugerindo uma redução homolítica do ChOOH. Como consequências, pode-se observar a oligomerização do citc, um processo que pode influenciar no transporte de elétrons bem como na sinalização para a apoptose. A partir da reação do citc com ChOOH podem surgir, direta ou indiretamente, outras espécies reativas, como aldeídos, cetonas e epóxidos. Dentre estas, destacam-se os aldeídos de colesterol, em particular o colesterol secoaldeído (CSec) e o carboxialdeído (ChAld), uma vez que foram encontrados elevados em placas ateroscleróticas e em tecidos cerebrais de pacientes com doenças neurodegenerativas. Tais espécies podem reagir com resíduos de aminoácidos provocando alterações estruturais e funcionais em proteínas. Neste sentido, o segundo capítulo deste trabalho tem como objetivo estudar a reação do ChAld com citc. Usando modelos mimétivos de membrana e espectrometria de massas, foi mostrado que o ChAld modifica covalentemente o citc por um mecanismo consistente com a formação de bases de Schiff. Tal modificação ocorre preferencialmente em resíduos de lisina que interagem com a membrana. Estas modificações influenciam na afinidade do citc pela membrana, aumentando sua aderência, o que pode ter influência no transporte de elétrons e sinalização para a apoptose. No terceiro e último capítulo deste trabalho nós buscamos uma ferramente analítica que permitisse analisar modificação de proteínas promovidas por produtos de oxidação de colesterol e outros esteróis. Em um estudo realizado em colaboração com o grupo do professor Porter na Universidade de Vanderbilt, utilizamos ensaios baseados em click chemistry para buscar proteínas modificadas. Para isso, foram sintetizados derivados de colesterol e 7-deidrocolesterol (7-DHC, precursor imediato do colesterol) contendo um grupo alquinil na sua cadeia lateral. Este grupo pode ser ligado a um grupo azida por meio de uma reação de cicloadição, em um processo conhecido como click chemistry. Após a síntese e caracterização dos derivados lipídicos contendo o grupo alquinil na cadeia lateral, células Neuro2a foram tratadas com o alquinil-7-DHC e o alquinil-colesterol para averiguar seu metabolismo. Análises por HPLC-MS/MS mostraram que ambos derivados contendo o grupo alquinil foram metabolisados e convertdos nos respectivos ésteres. Usando um modelo celular para a doença conhecida como Sindrome de Smith-Lemli-Opitz (SLOS), doença caracterizada pela deficiência na enzima 7-deidrocolesterol redutase, foi mostrado que o acúmulo característico de 7-DHC nos pacientes pode levar a uma maior modificação de proteínas promovidas por seus derivados, o que pode contribuir para o desenvolvimento da doença


Cholesterol is an important component of eukaryotic cellular membranes, where it has an influence in the fluidity and stability. Due to the presence of a double bond in its structure, cholesterol can be oxidized by reactive oxygen and nitrogen species. This non-enzymatic oxidation generates, as primary products, cholesterol hydroperoxides. Such molecules, in turn, are highly reactive and can react with free metal ions and/or metalloproteins, affecting cell metabolism. Therefore, the first chapter of the present study aims to investigate the reaction of cholesterol hydroperoxides (ChOOH) with cytochrome c (cytc), a heme protein involved in the mitochondrial electron transport. Spectroscopic analyses in the UV-Vis region showed that ChOOH induces a dose-dependent bleaching of cytc's Soret band. In addition, this reaction leads to the formation of carbon-centered radicals on both protein and lipid, suggesting a homolytic reduction of ChOOH. As consequences, cytc undergoes oligomerization, a process that can influence electron transport and apoptosis signaling. The reaction of cytc and ChOOH can produce, directly or indirectly, reactive species such as epoxides, aldehydes and ketones. Among them, cholesterol aldehydes, such as cholesterol secoaldehyde (CSec) and cholesterol carboxyaldehyde (ChAld), are of particular interest, since they were previously found elevated in atherosclerotic plaques and brain tissue of patients bearing neurodegenerative diseases. These species can also react with amino acid residues leading to protein denaturation and malfunction. With that in mind, the second chapter of this study aims to investigate the reaction of ChAld and cytc. Using mimetic membrane models and mass spectrometry analyses, we showed that ChAld covalently modifies cytc through a mechanism consistent with the formation of Schiff base adducts. Such modification occurs mostly at lysine residues that are known to interact with the membrane. The modifications have an influence in the affinity of cytc to the membrane, where they increase its binding to the membrane, a process that could affect the electron transport and apoptosis signaling. In the last and third chapter of this study we wanted an analytical tool that allowed the investigation of protein adduction promoted by cholesterol and other sterols-derived oxidation products. In a study performed in collaboration with the Porter group from Vanderbilt University, we used analyses based on click chemistry to search for protein adduction. To address that, we first synthesized derivatives of cholesterol and 7-dehydrocholesterol (7-DHC, the immediate precursor of cholesterol) containing an alkynyl group in the side chain. The alkynyl group can be ligated to an azide group through a cycloaddition reaction, in a process known as click chemistry. After the synthesis and characterization of alkynyl derivatives, Neuro2a cells were treated with alkynyl-7-DHC and alkynyl-cholesterol to check their metabolism. HPLC-MS/MS analyses showed that both alkynyl derivatives are metabolized and converted into their respective esters. In addition, using a cell model for Smith-Lemli-Optiz Syndrome (SLOS), a disease characterized by the deficiency in the dehydrocholesterol reductase 7, we showed that the characteristic accumulation of 7-DHC in SLOS patients might be associated with protein adduction promoted by its oxidation products, which might contribute to the development of the disease


Assuntos
Oxidação Química/análise , Colesterol Oxidase/sangue , Aldeídos/química , Cromatografia Líquida de Alta Pressão/instrumentação , Citocromos c/análise , Eucariotos , Radicais Livres , Peroxidação de Lipídeos , Espectrometria de Massas/métodos , Metaloproteínas , Ácido Peracético/análise , Síndrome de Smith-Lemli-Opitz
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