Neurocognitive function in adult residents of a mining district in Mexico after reducing manganese exposure: Follow-up after 11 years

BACKGROUND

Little is known about the neurotoxic effects of chronic exposure to airborne Mn once exposure has been reduced. The environmentally exposed and the reference adult populations evaluated in 2002 were followed, after an environmental management program (EMP) was implemented to reduce the exposure in a mining district in Mexico.

OBJECTIVE

The aim of this study was to compare the association between exposure to Mn and neurocognitive performance in environmentally exposed and reference groups of adults before and after EMP implementation.

METHODS

In 2013, the same battery of neurocognitive tests used in the initial study (2002) was applied to 58 adults exposed to airborne Mn and 30 adults from the reference community. A cumulative exposure index (CEI) was estimated for the study population before and after the EMP. Categorical outcomes were analyzed using logistic regression, and the resulting ORs were compared between studies. Continuous outcomes were analyzed using linear regression. All models were adjusted for age, years of education, socioeconomic status and blood lead levels.

RESULTS

Exposed adults from the post-EMP study showed an improvement in fine motor and verbal regulation of motor skills (OR < 1) compared to the exposed adults from the pre-EMP study (OR > 1). In both pre- and post-studies, the exposed adults showed a deterioration in their dynamic organization of motor activity compared to the reference group (p < 0.05); however, they showed no significant change in attention and working-memory performance.

DISCUSSION

After four years of a significant reduction in airborne Mn levels resulting from EMP implementation, chronically exposed adults showed an improvement in fine motor and verbal regulation of motor skills; however, the remaining areas of their motor and cognitive functions remained impaired.

Revisión rápida: monitoreo de la presencia e infectividad del virus SARS-CoV-2 y otros coronavirus en aguas residuales

Objetivo. Describir la evidencia sobre la presencia e infectividad de SARS-CoV-2 y otros coronavirus en aguas residuales y su potencial uso como herramienta de vigilancia epidemiológica. Material y métodos. Búsqueda de publicaciones en PubMed y medRxiv desde enero 2003 hasta el 8 de junio de 2020 de acuerdo con la guía de revisiones rápidas de Cochrane. Resultados. Se incluyeron 29 publicaciones. El ARN de SARS-CoV-2 no infectivo se encontró en agua residual hospitalaria, agua residual cruda, tratada y lodos de plantas de tratamiento. Los niveles cuantitativos de ARN viral en agua residual presentan relación con el número de casos de Covid-19. SARS-CoV-1 y otros coronavirus permanecieron infectivos en agua residual cruda hasta por dos días. Conclusiones. Hasta esta revisión no existe evidencia sobre la presencia de virus infectivos de SARS-CoV-2 en agua residual cruda o tratada. La cuantificación de ARN de SARS-CoV-2 en agua residual es útil para la vigilancia epidemiológica.

Prenatal exposure to VOCs and NOx and lung function in preschoolers

BACKGROUND

Several studies have shown that exposure to air pollutants affects lung growth and development and can result in poor respiratory health in early life.

METHODS

We included a subsample of 772 Mexican preschoolers whose mothers participated in a Prenatal Omega-3 fatty acid Supplements, GRowth, And Development birth cohort study with the aim to evaluate the impact of prenatal exposure to volatile organic compounds and nitrogen oxides on lung function measured by oscillation tests. The preschoolers were followed until 5 years of age. Anthropometric measurements and forced oscillation tests were performed at 36, 48, and 60 months of age. Information on sociodemographic and health characteristics was obtained during follow up. Prenatal exposure to volatile organic compounds and nitrogen oxides was evaluated using a land use regression models and the association between them was tested using a lineal regression and longitudinal linear mixed effect models adjusting for potential confounders.

RESULTS

Overall, the mean (standard deviation) of the measurements of respiratory system resistance and respiratory system reactance at 6, 8, and 10 Hz during the follow-up period was 11.3 (2.4), 11.1 (2.4), 10.3 (2.2) and -5.2 (1.6), -4.8 (1.7), and -4.6 hPa s L^-1 (1.6), respectively. We found a significantly positive association between respiratory resistance (β_Rrs6  = 0.011; 95%CI: 0.001, 0.023) (P < .05) and prenatal exposure to nitrogen dioxide and a marginally negatively association between respiratory reactance (β_Xrs6  = -11.40 95%CI: -25.26, 1.17 and β_Xrs8  = -11.91 95%CI: -26.51, 1.43) (P = .07) and prenatal exposure to xylene.

CONCLUSION

Prenatal exposure to air pollutants was significantly associated with the alteration of lung function measured by oscillation tests in these preschool children.

Women exposure to household air pollution after an improved cookstove program in rural San Luis Potosi, Mexico

The state government of San Luis Potosí (SLP), Mexico implemented an improved cookstove (ICS) program in rural areas. As part of the comprehensive program evaluation, we compared fine particulate material (PM_2.5) concentrations in kitchens and patios in treated (TH), and non-treated households (NTH), and analyzed pollutant levels according to patterns of fuels and devices use reported by the women. A panel study was conducted in 728 households (357 TH and 371 NTH) in three regions of SLP including two sampling rounds in 2015-16. Data on exposure determinants, ICS conditions and cooking practices were collected. Daily PM_2.5 in kitchen and patio was measured in a subsample. The average treatment effect was estimated using the double difference method. We constructed a mixed linear model to estimate PM_2.5 levels for the entire study sample and obtained personal exposure according to time-activity logs. NTH had lower socioeconomic status compared to TH. The average daily PM_2.5 concentrations in NTH compared to TH were 155.2 and 92.6 μg/m³ for kitchen and 35.4 and 39.8 μg/m³ for patio, respectively. PM_2.5 levels showed significant regional differences but no significant treatment effect. In many cases, the ICS was added to previous open fire and LPG use (stacking). The household size, kitchen ventilation, relative humidity, temperature and the ratio of indoor/outdoor PM_2.5 concentration were significant predictors of kitchen PM_2.5 levels. The daily PM_2.5 personal exposure was significantly reduced using ICS in good conditions or LPG (57 μg/m³) compared to the traditional open fire (86 μg/m³). This study strengthens the evidence on the potential daily PM_2.5 exposure reduction for women using an ICS in good conditions or LPG, displacing the polluting open fire. Comprehensive strategies tailored to the sociocultural context of the communities are needed to implement clean energy programs that achieve adoption and sustained use of ICS or LPG.

A follow-up study after an improved cookstove intervention in rural Mexico: Estimation of household energy use and chronic PM2.5 exposure

The benefits of improved biomass cookstoves (ICS) depends on their adoption and sustained use. Few studies have documented if and how they are used more than five years after being introduced. We conducted a 9-year prospective cohort study among young rural women in the highlands of Michoacan, Mexico. Participants had received a Patsari ICS during a community trial either in 2005 or 2006. With retrospective information collected in 2012-13, we studied the households' energy use, ICS survival, and cooking practices during the follow-up period. Using an exposure model constructed with personal PM_2.5 measurements in a subsample of homes at the time of the initial trial in 2005, we estimated the exposure associated with different energy use patterns during the follow-up period. The ICS had a mean lifespan of 4 years, after which more than half of the stoves were not in use; therefore, the use of open fire increased, particularly among the indigenous communities. ICS use peak was achieved two years after the initial trial, either exclusively or combined with open fire. Yearly household energy use and other variables were used to estimate chronic air pollution exposure. Mean PM_2.5 exposure during the follow-up period ranged from 51 to 319 μg/m³; the median was 102 and 146 μg/m³ for mainly ICS and mainly open fire use, respectively. The ICS has a useful period after which it needs maintenance, repair, or replacement. Unfortunately, many programs have not afforded a follow-up component. Exposure to biomass smoke air pollutants can be reduced by using an ICS instead of the traditional open fire. Household energy strategies should ensure equitable access to clean energy options adapted to local needs and preferences with culturally appropriate technology implemented on a sustainable perspective.

Environmental Health Promotion of a Contaminated Site in Mexico

Entangled in complex ecological, sociocultural, and economic systems, current environmental health problems require integrated participatory approaches. Alpuyeca, a semi-urban, highly marginalized community in South-Central Mexico burdened by lead and polychlorinated biphenyl (PCB) contamination, dengue fever, and intestinal diseases, illustrates this. Its residents are distinctive, however, for their concerted actions in the face of environmental problems and the presence of defenders of a prehispanic worldview based on the protection of nature. This article addresses the health impacts of an integrated environmental health promotion strategy implemented through a participatory action research intervention based on qualitative and quantitative methods. Different actors, sectors, dimensions, and knowledge types were harmonized in a collaborative space created specifically for our interdisciplinary research team, community residents and local authorities. Reflections, plans and actions were developed collectively in this space with the view of finding solutions anchored in the local culture. Results included sharp reductions in blood-lead concentrations among children, in entomological indices, and in PCB contamination, as well as capacity strengthening. Medium-level community participation was achieved. This work contributes evidence that participatory environmental health research can be effective in analyzing and reducing problems in communities with multiple environmental health concerns. It complements ecohealth and environmental health literacy approaches.

Mapeo Comunitario para impulsar la participación comunitaria dentro del diagnóstico de salud poblacional

Introducción: La salud pública tiene en el diagnóstico de salud poblacional una de las principales herramientas de investigación y planificación sanitaria. La participación activa de la población en el diagnóstico poblacional es fundamental y el mapeo comunitario es una técnica que la promueve. Objetivo: Presentar las aportaciones del uso del mapeo comunitario para la participación de la población durante el desarrollo del diagnóstico de salud poblacional. Métodos: Para dar evidencia de las aportaciones de ésta técnica, durante el desarrollo de los diagnósticos de salud, efectuados entre los años 2010 y 2014, en zonas rurales y suburbanas del centro de México, se efectuaron ejercicios de mapeo comunitario con diversos grupos poblacionales (niños, jóvenes y adultos de ambos sexos), quienes identificaban en el mapa aspectos tanto positivos como negativos de su comunidad, lo cual se plasmó en necesidades sentidas de la población. Resultados: A través del mapeo comunitario se despertó el interés y se logró estimular la participación poblacional en la identificación de necesidades, priorización de problemas y soluciones. Conclusiones: La inclusión del mapeo comunitario dentro del diagnóstico poblacional, propicia la participación y fortalece procesos organizativos, lo cual permite que se busquen soluciones a las problemáticas identificadas.

Prenatal Exposure to Nitrogen Oxides and its Association with Birth Weight in a Cohort of Mexican Newborns from Morelos, Mexico

Background

The Child-Mother binomial is potentially susceptible to the toxic effects of pollutants because some chemicals interfere with placental transfer of nutrients, thus affecting fetal development, and create an increased the risk of low birth weight, prematurity and intrauterine growth restriction.

Objective

To evaluate the impact of prenatal exposure to nitrogen oxides (NO_x) on birth weight in a cohort of Mexican newborns.

Methodology

We included 745 mother-child pair participants of the POSGRAD cohort study. Information on socio-demographic characteristics, obstetric history, health history and environmental exposure during pregnancy were readily available and the newborns’ anthropometric measurements were obtained at delivery. Prenatal NO_x exposure assessment was evaluated using a Land-Use Regression predictive models considering local monitoring from 60 sites on the State of Morelos. The association between prenatal exposure to NO_x and birth weight was estimated using a multivariate linear regression models.

Results

The average birth weight was 3217 ± 439 g and the mean of NO_x concentration was 21 ppb (Interquartile range, IQR = 6.95 ppb). After adjusting for maternal age and other confounders, a significant birthweight reduction was observed for each IQR of NO_x increase (ß = –39.61 g, 95% CI: –77.00; –2.21; p = 0.04).

Conclusions

Our results provides evidence that prenatal NO_x exposure has a negative effect on birth weight, which may influence the growth and future development of the newborn.

State of Children Environmental Health Research in Latin America

Background:

Promotion of biomedical research along with the development of evidence-based prevention policies have been suggested as an effective way to reduce environmental risks for children’s health in Latin America. However, there is little information on the current state of childhood environmental health research, which might help identify its strengths and limitations, as well as to design a strategy to improve the future of child environmental health research in the region.

Objective:

To describe the current state of environmental health research on children exposed to environmental pollutants in Latin America.

Methodology:

We performed a comprehensive search of published peer-reviewed environmental health articles (1994–2014), dealing with the exposure of Latin American children to chemical compounds. We described the type of studies and their research topics, and identified networks of co-authors. We also analyzed the relationship between research funding sources and the impact factor (IF) of the journal where research was published.

Results:

The average number of publications was about 20 per year. Mexico and Brazil produced almost 70% of the 409 identified papers. The most studied contaminant was lead, but research on this element has declined since 2005. Retrospective studies were the most frequent, and also showed a decreasing trend. Most studies did not assess health effects. Four groups of leading investigators and two collaboration models for scientific production were identified. Except for Mexico, there was very little collaboration with North American and European countries. Compared to articles that did not report financial support, those that received international funding had on average an IF around 7, and those with national funding reached a mean IF near 3.

Conclusion:

There is a limited number of publications and insufficient collaboration between Latin-American scientists. It is necessary to identify strategies to stimulate South-South-North alliances and strengthen the scarce research on the environmental health of children in the region.

Effects of manganese exposure on visuoperception and visual memory in schoolchildren

BACKGROUND

Manganese (Mn) is an essential metal involved in multiple physiological functions. Environmental exposure to airborne Mn is associated with neurocognitive deficits in humans. Children, whose nervous system is in development, are particularly susceptible to Mn neurotoxicity.

OBJECTIVE

The objective of this study was to assess the association between Mn environmental exposure, and effects on visuoperception and visual memory in schoolchildren.

METHODS

We assessed schoolchildren between 7 and 11 years old, with similar socioeconomic status, from the mining district of Molango (n=148) and Agua Blanca (n=119, non-mining area) in Hidalgo state, Mexico. The Rey-Osterrieth Complex Figure (ROCF) test was used to assess visuoperception and short-term visual memory. Hair manganese (MnH) concentrations were determined. Linear regression models were constructed to estimate the associations between MnH and ROCF scores, adjusted for potential confounders.

RESULTS

The geometric mean MnH was nine times higher in schoolchildren from the Mn mining area (5.25μg/g) than in schoolchildren from the non-mining area (0.55μg/g). For the ROCF Copy trial, MnH was significantly associated with an increase in distortion errors (tangency, closure), angle errors, overtracing (partial overtracing). In the Immediate Recall trial, MnH was significantly associated with increased overtracing (partial overtracing) and omissions, and negatively associated with the number of perceptual drawn units, total score and percentage immediate recall.

CONCLUSIONS

MnH is associated with alterations in visuoperception and short-term visual memory in schoolchildren exposed to airborne Mn.

Modeling and estimating manganese concentrations in rural households in the mining district of Molango, Mexico

Airborne manganese (Mn) is considered the most hazardous route of exposure since Mn particles can enter into the body through the lung and may access the brain directly through olfactory uptake, thereby bypassing homeostatic excretory mechanisms. Environmental indoor and outdoor manganese concentrations in PM2.5 were monitored in ten rural households from two communities of Hidalgo, Mexico, from 2006 to 2007. Indoor and outdoor air samples of PM2.5 were collected using MiniVol samplers, and Mn concentrations in the filters were measured using proton-induced X-ray emission (PIXE). An adjusted generalized linear mixed model was applied and then used for estimating indoor concentrations in non-monitored households. Our monitoring results showed a higher daily average concentration of indoor PM2.5 vs. outdoor PM2.5 (46.4 vs. 36.2 μg/m(3), respectively); however, manganese concentration in PM2.5 indoor and outdoor was 0.09 μg/m(3) in both sceneries. Predictor variables of indoor Mn concentration were outdoor Mn concentration (64.5% increase per 0.1 μg/m(3) change in Mn) and keeping the windows open (4.2% increase). Using these predictors, the average estimated indoor Mn concentration in PM2.5 was 0.07 μg/m(3) (SD = 0.05). Our results confirm the direct effect of outdoor Mn levels, opening house windows, and the distance to the mining chimney in indoor Mn levels in houses.

Population health diagnosis with an ecohealth approach

OBJECTIVE

To analyze the characteristics of health diagnosis according to the ecohealth approach in rural and urban communities in Mexico.

METHODS

Health diagnosis were conducted in La Nopalera, from December 2007 to October 2008, and in Atlihuayan, from December 2010 to October 2011. The research was based on three principles of the ecohealth approach: transdisciplinarity, community participation, gender and equity. To collect information, a joint methodology and several techniques were used to stimulate the participation of inhabitants. The diagnostic exercise was carried out in five phases that went from collecting information to prioritization of problems.

RESULTS

The constitution of the transdisciplinary team, as well as the participation of the population and the principle of gender/equity were differentials between the communities. In the rural community, the active participation of inhabitants and authorities was achieved and the principles of transdisciplinarity and gender/equity were incorporated.

CONCLUSIONS

With all the difficulties that entails the boost in participation, the incorporation of gender/equity and transdisciplinarity in health diagnosis allowed a holistic public health approach closer to the needs of the population.

Effect of Personal Exposure to PM2.5 on Respiratory Health in a Mexican Panel of Patients with COPD

Background: Air pollution is a problem, especially in developing countries. We examined the association between personal exposure to particulate matter with an aerodynamic diameter less than 2.5 µm (PM_2.5) on respiratory health in a group of adults with chronic obstructive pulmonary disease (COPD). Methods: All participants resided in Mexico City and during follow-up, personal exposure to PM_2.5, respiratory symptoms, medications, and daily activity were registered daily. Peak expiratory flow (PEF) was measured twice daily, from February through December, 2000, in 29 adults with moderate, severe, and very severe COPD. PEF changes were estimated for each 10 µg/m³ increment of PM_2.5, adjustment for severity of COPD, minimum temperature, and day of the sampling. Results: For a 10-µg/m³ increase in the daily average of a two-day personal exposure to PM_2.5, there was a significant 33% increase in cough (95% CI, range, 5‒69%), and 23% in phlegm (95% CI, range, 2‒54%), a reduction of the PEF average in the morning of −1.4 L/min. (95% CI , range, −2.8 to −0.04), and at night of −3.0 L/min (95% CI, range, −5.7 to −0.3), respectively. Conclusions: Exposure to PM_2.5 was associated with reductions in PEF and increased respiratory symptoms in adults with COPD. The PEF reduction was observed both at morning and at night.

Association between light absorption measurements of PM2.5 and distance from heavy traffic roads in the Mexico City metropolitan area

OBJECTIVE

To study the relationship between light absorption measurements of PM2.5 at various distances from heavy traffic roads and diesel vehicle counts in Mexico City.

MATERIALS AND METHODS

PM2.5 samples were obtained from June 2003-June 2005 in three MCMA regions. Light absorption (b abs) in a subset of PM2.5 samples was determined. We evaluated the effect of distance and diesel vehicle counts to heavy traffic roads on PM2.5 b abs using generalized estimating equation models.

RESULTS

Median PM2.5 b abs measurements significantly decrease as distance from heavy traffic roads increases (p<0.002); levels decreased by 7% (CI95% 0.9-14) for each 100 additional meters from heavy traffic roads. Our model predicts that PM2.5 b abs measurements would increase by 20% (CI95% 3-38) as the hourly heavy diesel vehicle count increases by 150 per hour.

CONCLUSION

PM2.5 b abs measurements are significantly associated with distance from motorways and traffic density and therefore can be used to assess human exposure to traffic-related emissions.

Effect of environmental manganese exposure on verbal learning and memory in Mexican children

Manganese (Mn) is an essential metal, but in excess it becomes neurotoxic. Children's developing nervous system may be especially vulnerable to the neurotoxic effects of overexposure to this metal. The aim of this study was to assess the effect of Mn exposure on verbal memory and learning in 7- to 11-year-old children. We tested 79 children living in the Molango Mn-mining district and 95 children from a non-exposed community in the same State of Mexico. The Children's Auditory Verbal Learning Test (CAVLT) was administered. Blood and hair samples were obtained to determine Mn concentrations using atomic absorption spectrophotometry. CAVLT performance was compared between the two groups and multilevel regression models were constructed to estimate the association between biomarkers of Mn exposure and the CAVLT scores. The exposed group presented higher hair and blood Mn (p<0.001) than the non-exposed group (median 12.6 vs. 0.6μg/g, 9.5vs. 8.0μg/L respectively), as well as lower scores (p<0.001) for all the CAVLT subscales. Hair Mn was inversely associated with most CAVLT subscales, mainly those evaluating long-term memory and learning (β=-0.47, 95% CI -0.84, -0.09). Blood Mn levels showed a negative but non-significant association with the CAVLT scores. These results suggest that Mn exposure has a negative effect on children's memory and learning abilities.

[Validation of reported location of solid waste using Procrustes analysis in the context of a participatory community initiative]

This study is part of a community initiative for integrated solid waste management based on "popular epidemiology" and participatory action research. The study proposes a method for validation of spatial data (X and Y data) on solid waste reported by community members. Location of sites was conducted by 76 residents of the La Nopalera community (Yautepec, Morelos, Mexico) and compared with reports by three environmental health experts. Agreement was explored using Procrustes analysis. Experts identified 23 sites with abundant solid waste, while community members only identified 22 sites. There were minimal differences in location, scale, and positioning of reported waste. Procrustes statistics showed 95% agreement between community and expert reports. The findings suggest that community knowledge can be a valid source of information in epidemiological studies, and that measurement error can be quantified. The simple methodology described here can be used in further "popular epidemiology" studies or similar approaches.

Elemental carbon exposure and lung function in school children from Mexico City

Though exposure to air pollution has a detrimental effect on respiratory health, few studies have examined the association between elemental carbon exposure and lung function among schoolchildren. The aim of the present study was to present the association between short-term elemental carbon exposure and lung function in schoolchildren from Mexico City. 55 asthmatic and 40 non-asthmatic children were followed for an average of 22 weeks. A spirometry test was performed every 15 days during follow-up. Portable air samplers collected particulate matter onto Teflon filters. Gravimetric analysis was conducted and elemental carbon was quantified using transmission densitometry. The association between the main variables was analysed using linear mixed effects models. The mean ± sd of elemental carbon light absorption was 92.7 ± 54.7 Mm(-1). An increase of one interquartile range in the 24-h average of elemental carbon (100.93 Mm(-1)) was associated with a significant negative impact on forced expiratory volume in 1 s (FEV(1)) (-62.0 (95% CI -123.3- -1.2) mL) and forced expiratory flow at 25-75% of forced vital capacity (FVC) (FEF(25-75%)) (-111 (95% CI -228.3- -4.1) mL) among asthmatic children, equal to 3.3% and 5.5%, respectively; and on FEV(1) (-95.0 (95% CI -182.3- -8.5) mL) and FVC (-105.0 (95% CI -197.0- -13.7) mL) among non-asthmatic children. Exposure to elemental carbon resulted in an important negative effect on lung function in atopic schoolchildren, regardless of asthma status.

Assessment of personal exposure to ozone in asthmatic children residing in Mexico City

OBJECTIVE

A study was conducted to evaluate personal ozone exposure (O3p) among asthmatic children residing in Mexico City.

MATERIAL AND METHODS

A total of 158 children were recruited from December 1998 to April 2000. On average, three O3p measurements were obtained per child using passive badges. Time-activity patterns were recorded in a diary. Daily ambient ozone measurements (O3a) were obtained from the fixed station, according to children's residence. Levels of O3a and ozone, weighted by time spent in different micro-environments (O3w), were used as independent variables in order to model O3p concentrations using a mixed-effects model.

RESULTS

Mean O3p was 7.8 ppb. The main variables in the model were: time spent indoors, distance between residence and fixed station, follow-up group, and two interaction terms (overall R(2)=0.50, p<0.05).

CONCLUSIONS

The O3w concentrations can be used as a proxy for O3p, taking into account time-activity patterns and the place of residence of asthmatic Mexican children.

Air pollution, airway inflammation, and lung function in a cohort study of Mexico City schoolchildren

BACKGROUND

The biological mechanisms involved in inflammatory response to air pollution are not clearly understood.

OBJECTIVE

In this study we assessed the association of short-term air pollutant exposure with inflammatory markers and lung function.

METHODS

We studied a cohort of 158 asthmatic and 50 nonasthmatic school-age children, followed an average of 22 weeks. We conducted spirometric tests, measurements of fractional exhaled nitric oxide (Fe(NO)), interleukin-8 (IL-8) in nasal lavage, and pH of exhaled breath condensate every 15 days during follow-up. Data were analyzed using linear mixed-effects models.

RESULTS

An increase of 17.5 microg/m(3) in the 8-hr moving average of PM(2.5) levels (interquartile range) was associated with a 1.08-ppb increase in Fe(NO) [95% confidence interval (CI), 1.01-1.16] and a 1.07-pg/mL increase in IL-8 (95% CI 0.98-1.19) in asthmatic children and a 1.16 pg/ml increase in IL-8 (95% CI, 1.00-1.36) in nonasthmatic children. The 5-day accumulated average of exposure to particulate matter <2.5 microm in aerodynamic diamter (PM(2.5)) was significantly inversely associated with forced expiratory volume in 1 sec (FEV(1)) (p=0.048) and forced vital capacity (FVC) (p=0.012) in asthmatic children and with FVC (p=0.021) in nonasthmatic children. Fe(NO) and FEV(1) were inversely associated (p=0.005) in asthmatic children.

CONCLUSIONS

Exposure to PM(2.5) resulted in acute airway inflammation and decrease in lung function in both asthmatic and nonasthmatic children.

Relationship between indoor, outdoor, and personal fine particle concentrations for individuals with COPD and predictors of indoor-outdoor ratio in Mexico city

Personal exposure and indoor and outdoor exposure to PM(10) and PM(2.5) of 38 individuals with chronic obstructive pulmonary disease (COPD) was characterized from February through November 2000. All participants lived in Mexico City and were selected based on their area of residence southeast (n=15), downtown (n=15), and southwest (n=8). Participants were monitored at home using personal PM(2.5) monitoring devices. Indoor and outdoor levels of PM(10) and PM(2.5) were measured using MiniVol samplers. Concurrent individual exposure measurements, indoor and outdoor levels of PM(2.5), which averaged 38.4 (SD 21.4), 30.6 (SD 15.8), and 30.5 mug/m(3) (SD 19.4), respectively. Indoor PM(2.5) concentrations explained 40% of the variability of personal exposure. In addition, the factors that most affected personal exposure were regular indoor contact with animals, mold, cooking activities, and aerosol use, indicating that internal sources may largely affect individual exposure.

Omega-3 fatty acid prevents heart rate variability reductions associated with particulate matter

CONTEXT

Environmental exposure to particulate matter of 2.5 microm or less (PM2.5) has been associated with changes in heart rate variability (HRV).

OBJECTIVE

To evaluate the effect of supplementation with omega-3 polyunsaturated fatty acids on the reduction of HRV associated with PM2.5 exposure.

DESIGN

Randomized double-blind trial.

SETTING

Mexico City, Mexico.

PARTICIPANTS

50 nursing home residents older than 60 yr.

INTERVENTION

Randomization to either 2 g/d of fish oil versus 2 g/d of soy oil as the control, with 6 mo follow-up (1-mo presupplementation and 5-mo supplementation) or repeated HRV measurements. PM2.5 was monitored indoors and outdoors.

MAIN OUTCOME MEASURE

The association between HRV and 1 SD change in PM2.5 (8 microg/m3).

RESULTS

In the group receiving fish oil, the reduction in HRV-high-frequency log(10)-transformed associated with a 1-SD change in PM2.5 was -54% (95% confidence interval, -72, -24) in the presupplementation phase, and only -7% (95% confidence interval, -20,+7) in the supplementation phase (p < 0.01 for the effect of supplementation), with changes in other HRV parameters also being significantly less pronounced during supplementation. Small decreases in PM2.5-associated reductions in HRV parameters also occurred in the group receiving soy oil, but these were not significant. Fish oil supplementation was significantly better in preventing the reduction in percentage of successive normal RR intervals differing by more than 50 ms (p = 0.03) and the root square of the mean of the sum of the squares of differences between adjacent intervals (p = 0.05) than soy oil supplementation.

INTERPRETATION

Supplementation with 2 g/d of fish oil prevented HRV decline related to PM2.5 exposure in the study population.

[Environmental PM2.5 levels and distance from a heavy traffic road in Ciudad Juarez, Chihuahua, Mexico]

OBJECTIVE

To assess PM2.5 levels at different distances from a heavy traffic road.

MATERIAL AND METHODS

Daily measurements of PM2.5 were taken between August 26 and 30, 2002, at different distances from Tecnológico Avenue in Ciudad Juarez, Chihuahua, Mexico. Data analysis consisted of descriptive statistics for each distance and KruskalWallis and cross trend for ranks.

RESULTS

We found a significantly decreasing trend of PM2.5 median levels with increasing distance from Tecnológico Avenue (p<0.001). At 100 m distance from the avenue, PM2.5 levels decreased by 9.5 microg/m3 (40.6%) when compared to median levels registered on the avenue. The results showed a highly significant negative correlation between PM2.5 measurements and the distance from the avenue (r=-0.70, n=20 and p=0.0005).

CONCLUSIONS

PM2.5 median levels decreased significantly after 100 meters from heavy traffic roads. These results are of great relevance when assessing exposure to PM2.5 in epidemiological studies.

[Trends in atmospheric concentrations of lead in the metropolitan area of Mexico city, 1988-1998]

OBJECTIVE

To describe the trends in airborne lead levels and their association with the control measures implemented from 1988 to 1998 to phase out lead from gasoline that included the introduction of a lead-free gasoline and the use of catalytic converters in automobiles in Mexico City.

MATERIAL AND METHODS

Data of atmospheric lead levels were obtained from the 9 field stations included in the local air quality monitoring network (RMMA). Trends for airborne lead are shown by monitor, monitoring area and for the entire metropolitan zone. Analysis of data was performed using linear regression models including auto correlation analysis. The models were validated by standard diagnostic techniques using student residuals analysis.

RESULTS

The introduction of lead-free gasoline and the use of catalytic converters decreased the airborne lead levels by 23% while the slow elimination of lead from gasoline produced a cumulative decrease of 89% during the period and in all areas studied.

CONCLUSIONS

The strategy implemented to reduce sources of airborne lead pollution had an important impact on atmospheric lead levels. Health risks of this environmental hazard are now primarily due to less important sources and to particular occupational exposures. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

[Evaluation of the indoor and outdoor air quality in a nursery school in Mexico City]

OBJECTIVE

To evaluate the differences between indoor and outdoor ozone (O3) and nitrogen dioxide (NO2) levels at a school located in southwest Mexico City.

MATERIAL AND METHODS

Indoor and outdoor O3 and NO2 levels were measured daily between January and April 1990 by manual monitoring.

RESULTS

Indoor and outdoor concentrations of nitrogen dioxide did not surpass the Mexican standard (0.21 ppm). The correlation coefficient between maximum NO2 concentrations measured by the city's local monitoring station and those measured outside the classroom was 0.82 (p < 0.001). Regarding ozone, its maximum outdoor concentration was 0.29 ppm and indoor concentrations were on average below 0.06 ppm (maximum = 0.17 ppm). The indoor/outdoor correlation coefficient was 0.72, and for every 1.7 ppm outside, there was 1.0 ppm inside (p < 0.05).

CONCLUSIONS

Since the highest outdoors O3 concentrations were observed between 11:00 and 14:00 hrs, it is recommendable to have recess before this time.

[Study of the validity and reproducibility of passive ozone monitors]

The aim of this study was to evaluate the validity and reproducibility between ozone measurements obtained with passive ozone monitors and those registered with a continuous ozone monitor, to determine the applicability of passive monitors in epidemiological research. The study was carried out during November and December 1992. Indoor and outdoor classroom air ozone concentrations were analyzed using 28 passive monitors and using a continuous monitor. The correlation between both measurements was highly significant (r = 0.089, p < 0.001), indicating a very good validity. Also, the correlation between the measurements obtained with two different passive monitors exposed concurrently was very high (r = 0.97, p < 0.001), indicating a good reproducibility in the measurements of the passive monitors. The relative error between the concentrations measured by the passive monitors and those from the continuous monitor tended to decrease with increasing ozone concentrations. The results suggest that passive monitors should be used to determine cumulative exposure of ozone exceeding 100 ppb, corresponding to an exposure period greater than five days, if used to analyze indoor air.