Trends in the contribution of greenhouse gas emissions from food and beverage purchases in Mexico: 1989-2020.

BACKGROUND: Assessing the trends in dietary GHGE considering the social patterning is critical for understanding the role that food systems have played and will play in global emissions in countries of the global south. Our aim is to describe dietary greenhouse gas emissions (GHGE) trends (overall and by food group) using data from household food purchase surveys from 1989 to 2020 in Mexico, overall and by education levels and urbanicity. METHODS: We used cross-sectional data from 16 rounds of Mexico's National Income and Expenditure Survey, a nationally representative survey. The sample size ranged from 11,051 in 1989 to 88,398 in 2020. We estimated the mean total GHGE per adult-equivalent per day (kg CO2-eq/ad-eq/d) for every survey year. Then, we estimated the relative GHGE contribution by food group for each household. These same analyses were conducted stratifying by education and urbanicity. RESULTS: The mean total GHGE increased from 3.70 (95%CI: 3.57, 3.82) to 4.90 (95% CI 4.62, 5.18) kg CO2-eq/ad-eq/d between 1989 and 2014 and stayed stable between 4.63 (95% CI: 4.53, 4.72) and 4.89 (95% CI: 4.81, 4.96) kg CO2-eq/ad-eq/d from 2016 onwards. In 1989, beef (19.89%, 95% CI: 19.18, 20.59), dairy (16.87%, 95% CI: 16.30, 17.42)), corn (9.61%, 95% CI: 9.00, 10.22), legumes (7.03%, 95% CI: 6.59, 7.46), and beverages (6.99%, 95% CI: 6.66, 7.32) had the highest relative contribution to food GHGE; by 2020, beef was the top contributor (17.68%, 95%CI: 17.46, 17.89) followed by fast food (14.17%, 95% CI: 13.90, 14.43), dairy (11.21%, 95%CI: 11.06, 11.36), beverages (10.09%, 95%CI: 9.94, 10.23), and chicken (10.04%, 95%CI: 9.90, 10.17). Households with higher education levels and those in more urbanized areas contributed more to dietary GHGE across the full period. However, households with lower education levels and those in rural areas had the highest increase in these emissions from 1989 to 2020. CONCLUSIONS: Our results provide insights into the food groups in which the 2023 Mexican Dietary Guidelines may require to focus on improving human and planetary health.

Binge drinking associated with mean temperature: a cross-sectional study among Mexican adults living in cities.

BACKGROUND: The association between environmental temperature and alcohol consumption has not been widely explored despite the potential that increasing temperatures could promote the consumption of alcoholic beverages and the alcohol-related burden of disease. We aimed to explore the association between temperature and binge drinking in Mexican adults from urban cities, overall, and by alcoholic beverage type. METHODS: Data on 10,552 adults ≥ 18 years was obtained from the 2016 National Survey on Drug, Alcohol, and Tobacco Consumption. The mean annual temperature at the municipality was obtained from the Mexican National Weather Service using monthly temperatures from 2015 to 2016. We analyzed binge drinking for all alcoholic beverages in the last year and by type of alcohol as beer, liquor, wine, and coolers. Associations between mean temperature over the past year and binge drinking over the past year among current drinkers were estimated using multilevel Poisson models with robust standard errors adjusted for age, sex, education level, marital status, and household socioeconomic status, with a fixed effect by region. RESULTS: We observed a non-significant increase in the prevalence of binge drinking for every difference of 1 °C between municipalities of the same region. By alcohol type, a 1 °C increase in mean annual temperature across municipalities of the same region increased the prevalence of beer binge drinking in the past year by 0.9% (PR = 1.009, 95%CI 1.005, 1.013) among beer consumers and the prevalence of coolers' binge drinking by 3.0% (PR = 1.030, 95%CI 1.003, 1.057) in coolers consumers. We observed non-significant results for liquor binge drinking (PR = 1.047, 95%CI 0.994, 1.102) and wine binge drinking (PR = 1.047, 95% 0.944, 1.161). CONCLUSION: People living in municipalities with higher temperatures reported a higher beer binge drinking in Mexican cities. This could account for 196,000 cases of beer binge drinking in 2016. The context of each country needs to be considered when generalizing these findings, and they need to be further explored with longitudinal data as there might be implications for climate change. If our findings are confirmed given the forecasted rising temperatures, we could expect an increase in binge drinking and therefore, in the alcohol burden of disease.

Warning labels on alcoholic beverage containers: a pilot randomized experiment among young adults in Mexico.

BACKGROUND: Little is known about the potential impacts of visible and up-to-date health warning labels on alcoholic beverage containers on a range of outcomes in low- and middle-income countries. We conducted an experimental study to test the potential impacts of visible health warning labels (on the principal panel of the package) on thinking about health risks, product attractiveness, visual avoidance, and intention to change alcohol use among students in Mexico aged 18-30 years. METHODS: A double-blind, parallel-group, online randomized trial was conducted from November 2021 to January 2022 in 11 states in Mexico. In the control group, participants were presented with the image of a conventional beer can with a fictional design and brand. In the intervention groups, the participants observed pictograms with a red font and white backgrounds (health warning label in red-HWL red) or with a black font and yellow backgrounds (health warning label in yellow-HWL yellow), located at the top, covering around one-third of the beer can. We used Poisson regression models -unadjusted and adjusted for covariates- to assess differences in the outcomes across study groups. RESULTS: Using intention-to-treat analysis (n = 610), we found more participants in groups HWL red and HWL yellow thought about the health risks from drinking beer compared to the control group [Prevalence Ratio (PR) = 1.43, CI95%:1.05,1.93 for HWL red; PR = 1.25, CI95%: 0.91, 1.71 for HWL yellow]. A lower percentage of young adults in the interventions vs control group considered the product attractive (PR 0.74, 95%CI 0.51, 1.06 for HWL red; PR 0.56, 95%CI 0.38, 0.83 for HWL yellow). Although not statistically significant, a lower percentage of participants in the intervention groups considered buying or consuming the product than the control group. Results were similar when models were adjusted for covariates. CONCLUSIONS: Visible health warning labels could lead individuals to think about the health risks of alcohol, reducing the attractiveness of the product and decreasing the intention to purchase and consume alcohol. Further studies will be required to determine which pictograms or images and legends are most contextually relevant for the country. TRIAL REGISTRATION: The protocol of this study was retrospectively registered on 03/01/2023: ISRCTN10494244.

Patrones de consumo de alcohol en adolescentes y adultos mexicanos: Ensanut Continua 2022.

OBJETIVO: Caracterizar los patrones de consumo (actual y excesivo) de alcohol en adolescentes y adultos mexicanos. Material y métodos. Se analizó información de la Encuesta Nacional de Salud y Nutrición Continua 2022 (Ensanut Continua 2022) representativa a nivel nacional y regional. Se estimaron las prevalencias de consumo de alcohol actual y consumo excesivo de alcohol en los últimos 12 meses y 30 días. RESULTADOS: En adolescentes, las prevalencias de consumo actual de alcohol, excesivo en los últimos 12 meses y 30 días fueron de 20.6, 13.9 y 5.2%. En adultos, las prevalencias de consumo actual de alcohol, excesivo en los últimos 12 meses y 30 días fueron 55.5, 40.4 y 19.1%. Las prevalencias fueron mayores en hombres que en mujeres, con diferencias significativas en adultos. En adolescentes, las prevalencias fueron mayores a mayor edad, nivel socioeconómico y en aquellos sin estudios. En adultos, las prevalencias fueron mayores a menor edad, mayor nivel socioeconómico y escolaridad, y en áreas metropolitanas. Conclusión. Estos resultados muestran la necesidad de fortalecer las acciones de implementación, seguimiento y protección ofrecidas por la estrategia SAFER para prevenir y reducir el consumo nocivo de alcohol en adolescentes y adultos.

Fraction of COVID-19 hospitalizations and deaths attributable to chronic diseases.

Evidence shows that chronic diseases are associated with COVID-19 severity and death. This study aims to estimate the fraction of hospitalizations and deaths from COVID-19 attributable to chronic diseases associated to poor nutrition and smoking among adults who tested positive to COVID-19 in Mexico. We analyzed 1,006,541 adults aged ≥20 who tested positive for COVID-19 from March 23 to December 5, 2020. Six chronic diseases were considered: obesity, chronic obstructive pulmonary disease (COPD), hypertension, diabetes, cardiovascular disease, and chronic kidney disease (CKD). We calibrated the database using a bias quantification method to consider undiagnosed disease cases. To estimate the total impact of multiple diseases, we defined a multimorbidity variable according to the number of diseases. Risks of hospitalization and death were estimated with Poisson regression models and used to calculate population attributable fractions (PAFs). Chronic diseases accounted for to 25.4% [95% CI: 24.8%-26.1%], 28.3% (95% CI: 27.8%-28.7%) and 15.3% (95% CI: 14.9%-15.7%) of the hospitalizations among adults below 40, 40-59, and 60 years and older, respectively. For COVID-19-related deaths, 50.1% (95% CI: 48.6%-51.5%), 40.5% (95% CI: 39.7%-41.3%), and 18.7% (95% CI, 18.0%-19.5%) were attributable to chronic diseases in adults under 40, 40-59, and 60 years and older, respectively. Chronic diseases linked to poor nutrition and smoking could have contributed to a large burden of hospitalization and deaths from COVID-19 in Mexico, particularly among younger adults. Medical and structural interventions to curb chronic disease incidence and facilitate disease control are urgently needed.

Bromine Substitution Effect on Structure, Reactivity, and Linear and Third-Order Nonlinear Optical Properties of 2,3-Dimethoxybenzaldehyde.

The structural and electronic properties of 2,3-dimethoxybenzaldehyde (2,3-DMB), 5-bromo-2,3-dimethoxybenzaldehyde (5-BRB), and 6-bromo-2,3-dimethoxybenzaldehyde (6-BRB) were extensively discussed with emphasis on linear and nonlinear optical responses. The intermolecular interactions were comparatively studied by Hirshfeld surfaces, quantum theory of atoms in molecules (QTAIM), and natural bond orbitals (NBOs), indicating that bromine substitution decreases the H···H and C···H contacts and increases H···Br and Br···Br closed-shell interactions on crystalline arrangements. The frontier molecular orbitals and molecular electrostatic potential map, carried out at the CAM-B3LYP/6-311++G(d,p) level of theory, showed that the kinetic stability occurs in the increasing order 6-BRB < 5-BRB < 2.3-DMB. The bromine atom has a beneficial effect on the nonlinear third-order susceptibility of 2,3-DMB, with theoretical predictions of 89.54 ×10-22 and 83.15 ×10-22 (m/V)2 for 6-BRB and 5-BRB, respectively. These findings were favorably compared with available theoretical and experimental data of other organic crystals that may be promising as NLO materials.

Soft drink and non-caloric soft drink intake and their association with blood pressure: the Health Workers Cohort Study.

BACKGROUND: A few prospective studies have investigated the potential association of soft drink and non-caloric soft drink intake with high blood pressure using methods that adequately consider changes in intake over time and hypertensive status at baseline. OBJECTIVE: To prospectively examine the association of soft drink and non-caloric soft drink intake with systolic and diastolic blood pressure in a sample of Mexican adults, overall and by hypertension status. METHODS: We used data from the Health Workers Cohort Study spanning from 2004 to 2018 (n = 1,324 adults). Soft drink and non-caloric soft drink intake were assessed with a semiquantitative food frequency questionnaire. We fit multivariable-adjusted fixed-effects models to test the association of soft drink and non-caloric soft drink intake with systolic and diastolic blood pressure. The models were adjusted for potential confounders and considering the potential modifying effect of hypertension status at baseline. RESULTS: A one-serving increase in soft drink intake was associated with a 2.08 mm Hg (95% CI: 0.21, 3.94) increase in systolic blood pressure and 2.09 mm Hg (95% CI: 0.81, 3.36) increase in diastolic blood pressure over ten years. A stronger association between soft drink intake and diastolic pressure was observed among participants with versus without hypertension at baseline. We found no association between non-caloric soft drink intake and blood pressure. CONCLUSIONS: Our findings support the hypothesis that soft drink intake increases blood pressure. While further studies should be conducted to confirm our findings, food policies and recommendations to limit soft drink intake are likely to help reduce blood pressure at the population level. We probably did not find an association between non-caloric soft drink intake and blood pressure because of the low consumption of this type of beverage in the cohort. More studies will be needed to understand the potential effect of non-caloric beverages on blood pressure.

Remarkable Nonlinear Properties of a Novel Quinolidone Derivative: Joint Synthesis and Molecular Modeling.

A novel 4(1H) quinolinone derivative (QBCP) was synthesized and characterized with single crystal X-ray diffraction. Hirshfeld surfaces (HS) analyses were employed as a complementary tool to evaluate the crystal intermolecular interactions. The molecular global reactivity parameters of QBCP were studied using HOMO and LUMO energies. In addition, the molecular electrostatic potential (MEP) and the UV-Vis absorption and emission spectra were obtained and analyzed. The supermolecule (SM) approach was employed to build a bulk with 474,552 atoms to simulate the crystalline environment polarization effect on the asymmetric unit of the compound. The nonlinear optical properties were investigated using the density functional method (DFT/CAM-B3LYP) with the Pople's 6-311++G(d,p) basis set. The quantum DFT results of the linear polarizability, the average second-order hyperpolarizability and the third-order nonlinear susceptibility values were computed and analyzed. The results showed that the organic compound (QBCP) has great potential for application as a third-order nonlinear optical material.

Second-order nonlinear optical properties of two chalcone derivatives: insights from sum-over-states.

In this study, a combined experimental and theoretical study of the nonlinear optical properties (NLO) of two chalcone derivatives, (E)-3-(2-methoxyphenyl)-1-(2-(phenylsulfonylamine)phenyl)prop-2-en-1-one (MPSP) and (E)-3-(3-nitrophenyl)-1-(2-(phenylsulfonylamine)phenyl)prop-2-en-1-one (NPSP), in DMSO is reported. The single crystal structures of the compounds, which differ only by the type and position of one substituent, were grown using the slow evaporation technique, and the main structural differences are discussed. The two-photon absorption and first-order hyperpolarizability measurements were performed via the Z-scan technique and hyper-Rayleigh scattering experiment in DMSO. The theoretical calculations were performed using the Density Functional Theory (DFT) at the CAM-B3LYP/6-311++G(d,p) level, and the sum-over-states (SOS) approach in both static and dynamic cases. Besides the electron conjugation achieved by the aromatic rings, olefins, and carbonyl groups, both compounds have a nearly flat chalcone backbone, which is believed to contribute to the nonlinear optical properties. MPSP and NPSP have different positions, even though they have roughly the same conformation and form C-HO interactions. For several studied frequencies, the HRS first hyperpolarizability values for MPSP are greater than those for NPSP, indicating that in most cases the NLO properties of MPSP are better. The comparison among the theoretical and experimental HRS first hyperpolarizability results showed a good agreement. In addition, the two-dimensional second order nonlinear optical spectra obtained from the sum-over-states model indicate good second-order NLO responses of the two chalcone derivatives under external fields. Our findings are important not only to show the potential nonlinear optical application of the two new compounds but also to gain an insight into how different chemical compositions might affect the crystal structures and physico-chemical properties.

Revisión rápida: probabilidad de contagio por infecciones respiratorias agudas en el transporte público colectivo.

Objetivo. Determinar el nivel de evidencia sobre la proba-bilidad de transmisión de enfermedades respiratorias agudas en el transporte público colectivo. Material y métodos. Se utilizó la metodología de revisiones rápidas de Cochrane. La estrategia de búsqueda abarcó una base de datos acadé-mica hasta el 10 de diciembre de 2020. Resultados. Se identificaron 16 manuscritos que cumplieron los criterios de selección. En estudios de cohorte agrupados se encontró que el momio de seroconversión por influenza A o B fue 54% mayor en personas con uso frecuente de transporte público colectivo en comparación con las personas con un uso poco frecuente (razón de momios: 1.54; IC95%:1.06-2.01). Conclusión. La probabilidad de contagio por enfermeda-des respiratorias agudas puede incrementar con el uso del transporte público colectivo. Algunas recomendaciones para reducir la probabilidad de contagio en el transporte público colectivo son el uso de cubrebocas y reducir el número de pasajeros y tiempo de traslado.

Family and household characteristics associated with seropositive cases to SARS-CoV-2 across Mexican households.

OBJECTIVE: To assess the association of family and housing characteristics with the number of seropositive cases to SARS-CoV-2 in households. MATERIALS AND METHODS: We analyzed 874 households from Encuesta Nacional de Salud y Nutrición (Ensanut) 2020 Covid-19 using Poisson regression models. RESULTS: The number of seropositive family members was higher among families composed of children/adolescents, adults and older adults, households with more than two members per bedroom, and among households with closed windows. No association was found for bathroom availability and piped water. CONCLUSIONS: Family composition and housing characteristics can impose significant structural barriers to safe home confinement.

Seroprevalencia de SARS-CoV-2 en niños y adolescentes mexicanos en edad escolar.

Objetivo. Estimar la seroprevalencia de SARS-CoV-2 en población de edad escolar en México. Material y métodos. Se categorizaron a niños y adolescentes que participaron en la Encuesta Nacional de Salud y Nutrición 2020 sobre Covid-19 (Ensanut 2020 Covid-19) por edad escolar y nivel educativo. En participantes seropositivos, se identificó la proporción de infecciones asintomáticas. Se estimaron razones de prevalencia usando un modelo de regresión log-binomial. Resultados. La seroprevalencia en educación básica y media fue de 18.7% (IC95%: 14.9, 22.5) y 26.7% (IC95%: 22.1, 31.3), respectivamente. La infección asintomática fue más frecuente en educación básica (88.5% [IC95%: 80.5, 93.5]). Conclusiones. En población de educación básica la infección por SARS-CoV-2 es baja y usualmente asintomática.

Elimination of total coliforms and Escherichia coli from water by means of filtration with natural clays and silica sand in developing countries.

This research presents the results of a pilot system used for water treatment to be supplied to single-family or small housing nucleus at rural sector. The pilot system is constituted by an up-flow aerated filter with ceramic carrier, followed by a second down-flow filter of silica sand. The pilot plant was installed in a rural sector of the province of Loja, Ecuador, with the main purpose of monitoring the reduction in bacteria in the water for human consumption. Two natural clays from the area were tested. They were transformed into sphere-type ceramics, and then, they were placed in the pilot filters. These both natural clays are inorganic materials with high content of aluminosilicate clay minerals with favourable characteristics to achieve greater efficiency for the reduction in bacteria. The acclimatization time of 60 days allowed to achieve optimum treatment efficiency performance until 90 days of operation. The physicochemical parameters, namely temperature, pH, dissolved oxygen and total dissolved solids, were monitored throughout the experiments. Regarding microbiological parameters, up to 99% of total coliforms removal was reached for the clay called CF-CC and 79% for the other, called CF-CV. In addition, 100% of total coliforms and Escherichia Coli removal was reached for both clay systems. Social and economic viability of the proposed treatment is also analysed in the manuscript.

Predicting obesity reduction after implementing warning labels in Mexico: A modeling study.

BACKGROUND: In October 2019, Mexico approved a law to establish that nonalcoholic beverages and packaged foods that exceed a threshold for added calories, sugars, fats, trans fat, or sodium should have an "excess of" warning label. We aimed to estimate the expected reduction in the obesity prevalence and obesity costs in Mexico by introducing warning labels, over 5 years, among adults under 60 years of age. METHODS AND FINDINGS: Baseline intakes of beverages and snacks were obtained from the 2016 Mexican National Health and Nutrition Survey. The expected impact of labels on caloric intake was obtained from an experimental study, with a 10.5% caloric reduction for beverages and 3.0% caloric reduction for snacks. The caloric reduction was introduced into a dynamic model to estimate weight change. The model output was then used to estimate the expected changes in the prevalence of obesity and overweight. To predict obesity costs, we used the Health Ministry report of the impact of overweight and obesity in Mexico 1999-2023. We estimated a mean caloric reduction of 36.8 kcal/day/person (23.2 kcal/day from beverages and 13.6 kcal/day from snacks). Five years after implementation, this caloric reduction could reduce 1.68 kg and 4.98 percentage points (pp) in obesity (14.7%, with respect to baseline), which translates into a reduction of 1.3 million cases of obesity and a reduction of US$1.8 billion in direct and indirect costs. Our estimate is based on experimental evidence derived from warning labels as proposed in Canada, which include a single label and less restrictive limits to sugar, sodium, and saturated fats. Our estimates depend on various assumptions, such as the transportability of effect estimates from the experimental study to the Mexican population and that other factors that could influence weight and food and beverage consumption remain unchanged. Our results will need to be corroborated by future observational studies through the analysis of changes in sales, consumption, and body weight. CONCLUSIONS: In this study, we estimated that warning labels may effectively reduce obesity and obesity-related costs. Mexico is following Chile, Peru, and Uruguay in implementing warning labels to processed foods, but other countries could benefit from this intervention.

Soft drink intake is associated with weight gain, regardless of physical activity levels: the health workers cohort study.

BACKGROUND: While soft drink intake is positively associated with weight gain, no previous study has investigated whether leisure-time physical activity modifies this association. We estimated the association between soft drink intake and body weight, and explored if this association differed by levels of leisure-time physical activity. METHODS: We used data from the health workers cohort study, a prospective study of Mexican adults (20 to 85y old), including 1268 health workers and their families, who were assessed at baseline (2004-2006) and follow-up (2010-2012). We assessed soft drink intake (cola and flavored soda) using a validated food frequency questionnaire. We measured leisure-time physical activity using a self-report questionnaire, and categorized according to the 2010 World Health Organization (WHO) recommendations. Body weight was measured by trained personnel. The association between changes in soft drink intake and weight change, and if such association varied by levels of physical activity was estimated through fixed-effect models. RESULTS: An increase in one serving per day of soft drink was associated with 0.10 kg (95% CI 0.00, 0.19) increase in weight per year. This association was not modified by leisure-time physical activity, as demonstrated by the magnitude of the coefficient of the interaction between soft drink, leisure-time physical activity, and time (- 0.03 kg, 95% CI - 0.27 to 0.21); people who complied with the WHO physical activity recommendations gained 0.36 kg/year per serving of soft drink, compared to 0.48 kg/year for people without sufficient physical activity. CONCLUSIONS: Soft drink intake was associated with weight gain. Leisure-time physical activity did not modify the association between soft drink intake and weight gain. This finding challenges the idea that leisure-time physical activity is sufficient to counterbalance weight gain associated to soft drink intake.

Regular consumption of soft drinks is associated with type 2 diabetes incidence in Mexican adults: findings from a prospective cohort study.

BACKGROUND: Although high consumption of soft drinks has been associated with excess of type 2 diabetes risk, the strength of this association in the Mexican population, where a type 2 diabetes genetic susceptibility has been well established, has been scarcely studied. This study aimed to estimate the risk of type 2 diabetes due to soft drinks consumption in a cohort of Mexicans. METHODS: We used data on 1445 participants from the Health Workers Cohort Study, a prospective cohort conducted in Cuernavaca, Mexico. Soft drinks consumption was assessed with a semi-quantitative 116-item food frequency questionnaire. Incident type 2 diabetes was defined as self-report of physician-diagnosed type 2 diabetes, fasting glucose > 126 mg/dl, or hypoglycemic medication at any examination. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models. RESULTS: With a total of 9526.2 person-years of follow-up, 109 incident cases of type 2 diabetes were observed. Type 2 diabetes incidence rate was 7.6, 11.0, and 17.1 per 1000 person-years across levels of soft drinks consumption of < 1, 1-4, and ≥ 5 servings/week, respectively (p < 0.001 for trend). The intake of ≥5 soft drinks/week was significantly associated with an increased risk of type 2 diabetes (HR 1.9 95% CI:1.0-3.5) compared with consumption of < 1/week (p-trend = 0.040). The HR was attenuated by further adjustment for body mass index (HR 1.5 95%CI:0.8-2.8) and abdominal obesity (HR 1.6 95%CI:0.8-3.0). CONCLUSIONS: The consumption of soft drinks was associated with a higher risk of type 2 diabetes in a cohort of Mexican adults. Our results further support recommendations to limit soft drinks intake to address the growing diabetes epidemic in Mexico.

[Rapid review of the use of community-wide surgical masks and acute respiratory infections]. / Revisión rápida del uso de cubrebocas quirúrgicos en ámbito comunitario e infecciones respiratorias agudas.

OBJECTIVE: To assess the effectiveness of using surgical masks in community settings to reduce the probability of infection by SARS-CoV-2 or other acute viral respiratory infection, compared to not using surgical masks. MATERIALS AND METHODS: We followed the Cochrane rapid review methodology. The search strategy encompasses one academic database and pre-prints until April 1, 2020. Titles and abstracts were reviewed by one investigator. The full text review was divided among three researchers. The results were synthesized in a narrative way. RESULTS: 713 manuscripts were identified, of which 21 met the inclusion criteria. Of six systematic reviews, four found no reduction in the probability of transmission. Experimental home studies found no differences in the probability of contagion associated with the use of mouth masks. Only one modeling study estimated a 20% reduction in the incidence of acute respiratory disease, assuming that 10 to 50% of the population use the surgical masks correctly. CONCLUSIONS: The scientific evidence is inconclusive to recommend or discourage the use of surgical masks at the population level. Considering the potential negative effects, official recommendations should await for the results of natural experiments currently occurring in countries that have recommended the use of face masks at the population level.

OBJETIVO: Evaluar la efectividad del uso de cubrebocas quirúrgico en ámbitos comunitarios para reducir la probabilidad de contagio por SARS-CoV-2 u otra infección respiratoria aguda viral, en comparación con no usar cubrebocas. MATERIAL Y MÉTODOS: Se utilizó la metodología de revisiones rápidas de Cochrane. La estrategia de búsqueda abarcó una base de datos académica y pre-prints hasta el 1 de abril de 2020. Los títulos y resúmenes fueron revisados por un investigador. La revisión de textos completos fue dividida entre tres investigadores. Los resultados fueron sintetizados de forma narrativa. RESULTADOS: Se identificaron 713 manuscritos, de los cuales 21 cumplieron los criterios de inclusión. De seis revisiones sistemáticas, cuatro no encontraron reducciones en la probabilidad de contagio y seis estudios experimentales en hogares no encontraron diferencias en la probabilidad de contagio asociado con el uso de cubrebocas. Únicamente un estudio de modelaje estimó una reducción de 20% en la incidencia de enfermedad respiratoria, asumiendo que 10 a 50% de la población hace uso correcto de cubrebocas quirúrgicos. CONCLUSIONES: La evidencia científica no es concluyente para recomendar o desalentar el uso de cubrebocas a nivel poblacional. Considerando los potenciales efectos negativos, las recomendaciones gubernamentales deberían esperar a los resultados de los experimentos naturales en países que han recomendado la utilización poblacional de cubrebocas.

Human health risks from fish consumption following a catastrophic gas oil spill in the Chiquito River, Veracruz, Mexico.

An industrial accident resulted in a gas oil spill of 11,808 barrels in the upper part of the Coatzacoalcos River watershed. After river shore cleanup, concentrations of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH) in muscle (+ skin) were determined in captured fish to evaluate human health risk due to fish consumption post-spill in the most affected communities. Data on fish consumption, body weight, and diet factor were collected by questionnaires and field observations. Using standard formulas for carcinogenic and non-carcinogenic substances, site-specific remediation levels were calculated in fish, comparing them to the real levels observed. Likewise, the levels of PAHs in fish captured pre- and post-spill were compared to determine their origin (pyrolytic vs. petrogenic). The TPH concentrations were between 119,000 and 523,000 ng/g (dry weight) and no significant difference (P > 0.05) was found pre- vs. post-spill. The concentration of total PAHs varied between 2494.83 and 35,412.23 ng/g (dry weight), with the concentrations of naphthalene (520.9 ng/g) and phenanthrene (7532.7 ng/g) being much higher than in control samples, and being from the gas oil spill (petrogenic origin). The site-specific remediation levels calculated for TPH and PAH were much higher than the maximum levels actually detected. No human health risks were found from hydrocarbons from the spill, at least after cleanup efforts and natural attenuation (six months).

A Comprehensive Topological Analysis on a New Bromine-Chalcone with Potential Nonlinear Optical Properties.

The application of organic crystals on nonlinear optical (NLO) materials has been increasing in recent years, and compounds like chalcones are interesting due to their significant third-order nonlinear properties. Hereof, we describe the synthesis, molecular structure, supramolecular arrangement, and theoretical calculations for a bromine-chalcone 3-(4-bromophenyl)-1-[3-(2-oxo-2-phenylethoxy)phenyl]-propenone (BC), which crystallized into noncentrosymmetric space group Pc. Also, a comprehensive topological analysis performed by QTAIM highlights the observed halogen bonds on solid state. In addition, the thermal stability was studied in temperatures smaller than 800 °C showing BC crystal as potential optical devices at temperatures up to 250 °C. Finally, the NLO properties indicate a photonic application based on strong third-order nonlinear response.

Archaeal and bacterial community dynamics and bioprocess performance of a bench-scale two-stage anaerobic digester.

Two-stage technologies have been developed for anaerobic digestion of waste-activated sludge. In this study, the archaeal and bacterial community structure dynamics and bioprocess performance of a bench-scale two-stage anaerobic digester treating urban sewage sludge have been studied by the means of high-throughput sequencing techniques and physicochemical parameters such as pH, dried sludge, volatile dried sludge, acid concentration, alkalinity, and biogas generation. The coupled analyses of archaeal and bacterial communities and physicochemical parameters showed a direct relationship between archaeal and bacterial populations and bioprocess performance during start-up and working operation of a two-stage anaerobic digester. Moreover, results demonstrated that archaeal and bacterial community structure was affected by changes in the acid/alkalinity ratio in the bioprocess. Thus, a predominance of the acetoclastic methanogen Methanosaeta was observed in the methanogenic bioreactor at high-value acid/alkaline ratio, while a predominance of Methanomassilicoccaeceae archaea and Methanoculleus genus was observed in the methanogenic bioreactor at low-value acid/alkaline ratio. Biodiversity tag-iTag sequencing studies showed that methanogenic archaea can be also detected in the acidogenic bioreactor, although its biological activity was decreased after 4 months of operation as supported by physicochemical analyses. Also, studies of the VFA producers and VFA consumers microbial populations showed as these microbiota were directly affected by the physicochemical parameters generated in the bioreactors. We suggest that the results obtained in our study could be useful for future implementations of two-stage anaerobic digestion processes at both bench- and full-scale.