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.

Impact of an intervention for reducing waste through educational strategy: A Mexican case study, what works, and why?

Generation and inadequate management of solid waste constitute a global challenge. Projections for 2050 portend an annual increase of 3.40 billion tons of waste. This study assessed the impact of an environmental education intervention (EEI) aimed at reducing waste generation and fomenting pro-environmental behaviors in an academic public-health institution in Mexico. The EEI was implemented over 20 months using a model of behavior change. Using a mixed-method design (QUAN + qual), baseline and follow-up measurements were performed through electronic questionnaires (n = 754), focus groups (n = 20), and waste quantification. A double-difference model was performed to measure pro-environmental behaviors impact: overall and by sex, age, educational level and function within the institution. Waste quantification was performed using a quartering method and weekly monitoring. The qualitative data were studied through thematic analysis. As a result of the EEI, women reduced their use of multilayer packaging (-15.6 pp, p < 0.05) and frequent use of non-ecological materials (-17.6 pp, p < 0.05). Graduate-level participants reduced their regular and frequent use of these materials (-33.3 pp, p < 0.05, 27.6 pp, p < 0.01), while those with lower educational levels increased their ecological behavior at home (12.1 pp, p < 0.05). Waste generation dropped by 60.1% vis-a-vis the baseline measurement. Our qualitative findings showed a relationship between holding a position of power in the institution and recycling. They also revealed that available infrastructure for separating waste contributed substantially to the observed impact. With actions centered on physical structure, community practice and institutional policy components, the EEI improved the pro-environmental behaviors and perceptions of participants.

Verbal Memory and Learning in Schoolchildren Exposed to Manganese in Mexico.

Manganese (Mn) is an essential nutrient for cellular function, but in high concentrations, it is neurotoxic. Environmental exposure to Mn has been associated with cognitive effects in children. This study aimed to assess the effect of environmental exposure to Mn on verbal memory and learning in schoolchildren residents from two municipalities in the state of Hidalgo, Mexico. Cross-sectional studies were conducted in 2006 and 2013 with a total of 265 schoolchildren of 7 to 11 years old. Children's Auditory Verbal Learning Test-2 (CAVLT-2) was used to assess verbal memory and learning. Mn exposure tertiles were defined according to hair manganese (MnH) levels determined by atomic absorption spectrophotometry. Linear regression models were used to estimate the association between MnH levels and CAVLT-2 scores. The models were adjusted by potential confounders. The lowest and highest exposure tertiles were defined below and above MnH levels of ≤ 0.72 and ≥ 3.96 µg/g, respectively. Mn exposure was significantly associated with an average of 5- to 9-point decrease in learning curves and summary CAVLT-2 scores in the highest tertile. This study adds to the evidence of decreased verbal memory and learning in schoolchildren environmentally exposed to manganese.

Socio-environmental assessment of a landfill using a mixed study design: A case study from México.

Municipal solid waste management is a challenge for local authorities since mismanagement leads to environmental damage and social discontent. The objective of this study was to assess in an integrated manner the socio-environmental situation of a municipal landfill from México, using a design of mixed methods, which considered a quantitative evaluation of physicochemical and microbiological variables measured in leachates, surface and groundwater samples, soil and air, and a qualitative evaluation by in-depth interviews with the near-by inhabitants about their perception of the impacts of the landfill. The results show that leachates polluted the soil and surface water in a radius of up to 500 m from the landfill, but did not reach the groundwater, while the mean concentrations of PM10, Mn, and Ni measured in air samples at the landfill of 146 µg m-3, 0.12 µg m-3, 0.10 µg m-3, respectively, in the dry season and of Mn and Ni of 0.13 µg m-3 and 0.11 µg m-3, respectively, in the rainy season, surpassed permissible limits. From the residents perspective the landfill pollutes soil, water and air and it contributes to vehicle traffic and noise, promotes harmful fauna and disturbs the esthetic view. Air measurements coincide with social perception and in general, the applied mixed study design helped to assess in an integrated manner the socio-environmental concerns and to give advice to improve the current management of the landfill.

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 (ß=-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.

Manganese exposure and cognitive deficits: a growing concern for manganese neurotoxicity.

This symposium comprised five oral presentations dealing with recent findings on Mn-related cognitive and motor changes from epidemiological studies across the life span. The first contribution highlighted the usefulness of functional neuroimaging of the central nervous system (CNS) to evaluate cognitive as well as motor deficits in Mn-exposed welders. The second dealt with results of two prospective studies in Mn-exposed workers or welders showing that after decrease of Mn exposure the outcome of reversibility in adverse CNS effects may differ for motor and cognitive function and, in addition the issue of plasma Mn as a reliable biomarker for Mn exposure in welders has been addressed. The third presentation showed a brief overview of the results of an ongoing study assessing the relationship between environmental airborne Mn exposure and neurological or neuropsychological effects in adult Ohio residents living near a Mn point source. The fourth paper focused on the association between blood Mn and neurodevelopment in early childhood which seems to be sensitive to both low and high Mn concentrations. The fifth contribution gave an overview of six studies indicating a negative impact of excess environmental Mn exposure from air and drinking water on children's cognitive performance, with special attention to hair Mn as a potential biomarker of exposure. These studies highlight a series of questions about Mn neurotoxicity with respect to cognitive processes, forms and routes of exposure, adequate biomarkers of exposure, gender differences, susceptibility and exposure limits with regard to age.

Chlorpyrifos and neurodevelopmental effects: a literature review and expert elicitation on research and policy

Organophosphate pesticides are widely used on food crops grown in the EU. While they have been banned from indoor use in the US for a decade due to adverse health effects, they are still the most prevalent pesticides in the EU, with Chlorpyrifos (CPF) being the most commonly applied. It has been suggested CPF affects neurodevelopment even at levels below toxicity guidelines. Younger individuals may be more susceptible than adults due to biological factors and exposure settings.

Serum prolactin rises in Mexican school children exposed to airborne manganese.

Early studies on manganese (Mn) exposure have shown that this transition metal affects dopamine neurotransmission. Dopamine serves as a tonic inhibitor of prolactin release in the anterior hypophysis, thus the serum prolactin levels in occupationally Mn exposed workers has been found increased. However, little is known about environmental Mn exposure effect on this hormone. In the present study we assessed serum prolactin in environmentally (mainly through air) exposed children living in the proximity of a rich Mn zone in Mexico and a control group with similar socioeconomic and ethnic characteristics. We also determined Mn levels in blood and hair, hemoglobin and anthropometric variables. Children between 7 and 11 years old were included (77 from Mn exposed and 93 from control communities). Blood Mn was higher in exposed children (median 9.5 µg/L, rank [5.5, 18]) as compared to the control group (median 8 µg/L, rank [5, 14]) (p<0.05, Mann-Whitney). Hair Mn was also increased in the exposed group (median 13.2 µg/g, rank [4.2, 48]) in comparison to the control group (median 0.6 µg/g rank [0.06, 3.6]). Prolactin was found increased in the exposed children (median 12.35 ng/ml, rank [2.90, 33.70]) versus controls (median 7.77 ng/ml, rank [2.7, 23.6]). Positive correlations were found between prolactin and both blood Mn and hair Mn (Rho=0.217 and 0.250, respectively, p<0.05). A linear regression, with prolactin as the dependent variable, showed hair Mn as the determinant variable after adjusting by age, hemoglobin and sex. After a stratification of hair and blood Mn into low, medium and high content, significant associations were also found, confirming the relationship between prolactin and hair Mn. Results suggest that children from these Mn environmentally exposed communities could be at risk of endocrine alterations.

Environmental exposure to manganese and motor function of children in Mexico.

OBJECTIVES: Occupational manganese (Mn) exposure has been associated with motor deficits in adult workers, but data on the potential effects of environmental exposure to Mn on the developing motor function for a children population is scarce. The aim of this study was to evaluate the association between exposure to Mn and motor function of school aged children. METHODS: We conducted a cross-sectional study selecting 195 children (100 exposed and 95 unexposed) between 7 and 11 years old. The following tests were used to evaluate the motor function: Grooved pegboard, finger tapping, and Santa Ana test. Mn exposure was assessed by blood (MnB) and hair concentrations (MnH). We constructed linear regression models to evaluate the association between exposure to Mn and the different test scores adjusting for age, sex, maternal education, hemoglobin and blood lead. RESULTS: The median concentration of MnH and MnB was significantly higher in exposed (12.6 µg/g and 9.5 µg/L) compared to unexposed children (0.6 µg/g and 8.0 µg/L). The exposed children on average performed the grooved pegboard test faster, but made more errors, although these results did not reach statistical significance with neither one of the Mn exposure biomarkers. MnB showed an inverse association on the execution of the finger tapping test (average in 5 trials ß -0.4, p=0.02), but no association was observed with MnH. CONCLUSIONS: A subtle negative association of Mn exposure on motor speed and coordination was shown. In adults, the main effect of environmental Mn exposure has been associated with motor skills, but these results suggest that such alterations are not the main effect on children.

Respiratory health effects of indoor air pollution.

Domestic pollution is relevant to health because people spend most of their time indoors. One half of the world's population is exposed to high concentrations of solid fuel smoke (biomass and coal) that are produced by inefficient open fires, mainly in the rural areas of developing countries. Concentrations of particulate matter in kitchens increase to the range of milligrams per cubic meter during cooking. Solid fuel smoke possesses the majority of the toxins found in tobacco smoke and has also been associated with a variety of diseases, such as chronic obstructive pulmonary disease in women, acute respiratory infection in children and lung cancer in women (if exposed to coal smoke). Other tobacco smoke-associated diseases, such as tuberculosis, asthma, respiratory tract cancer and interstitial lung diseases, may also be associated with solid fuel smoke inhalation, but evidence is limited. As the desirable change to clean fuels is unlikely, efforts have been made to use efficient, vented wood or coal stoves, with varied success due to inconsistent acceptance by the community.

Short communication: impact of climate variability on the incidence of dengue in Mexico.

We evaluated the impact of weather variables and climatic indicators associated with the incidence of dengue in two municipalities of the state of Veracruz, Mexico, from 1995 to 2003. A retrospective ecological study was conducted, using time-series analysis in which we compiled the weekly reported cases of dengue and the weather and climatic parameters: temperature, rainfall and sea-surface temperature (SST), the latter as an El Niño Southern Oscillation indicator. We statistically evaluated the data with autogressive models. The models' predictive abilities were evaluated using data collected from 1995 to 2002 and were validated with those observed for 2003. Each degree Centigrade increase in SST was followed by an increase in the number of dengue cases: 46% in San Andrés Tuxtla (P = 0.001) 16 weeks later and 42% in Veracruz 20 weeks later (P = 0.002). Increases in weekly minimum temperature and rainfall were also significant factors in the increase in the reported cases of dengue. We recommend future studies using the same method, involving larger populations with different geographic location, climate and weather. We also recommend strengthening environmental, health and entomological surveillance systems to improve preparedness and emergency responses.

Household firewood use and the health of children and women of Indian communities in Chiapas, Mexico.

A follow-up study in two rural communities in the state of Chiapas, Mexico, compared families that used an improved stove for cooking with those that used traditional open-fire stoves, to assess the risks of respiratory symptoms in children and women exposed to wood smoke. 16-hour measurements showed that the concentration of particles less than 10 microm in diameter was significantly lower in households with the better stoves in the kitchen area, where children usually play, i.e., 158 microg/m3 vs 305 microg/m3 (p = 0.03). Multivariate models showed that using the better stove tended to protect against symptoms such as the common cold in children (RR 0.24; 9.5% CI 0.05, 1.02). Use of more firewood was linked to greater risks of experiencing difficulty breathing (RR 1.15; 95% CI 1.04, 1.27) and the common cold (RR 1.09; 95% CI 1.01, 1.18) in women. The use of stoves that require less wood for cooking reduces the risks of respiratory symptoms that may contribute to complicated respiratory diseases and mortality.

[Sociodemographic characteristics of people who died from pulmonary tuberculosis in Veracruz, Mexico, 1993]. / Características sociodemográficas de personas que murieron por tuberculosis pulmonar en Veracruz, México, 1993.

OBJECTIVE: We describe the socio-demographic and medical care characteristics of people who died of pulmonary tuberculosis in 1993 in the state of Veracruz, Mexico. MATERIAL AND METHODS: Once selected, through death certificate, an interview and verbal autopsy was applied to the closest available relative. RESULTS: A total of 300 interviews were carried out. Half of the deaths were diagnosed with tuberculosis the same year they died. Approximately half of the deceased withdrew from treatment and 40% reported abuse of alcohol consumption. Patients who died of pulmonary tuberculosis belonged to the most vulnerable social groups. 35% were illiterate or had no education, and 67% lacked a regular job. There were no differences found between those who used private medical services and those who used official or public services. CONCLUSIONS: Important findings include the high proportion of patients diagnosed in advanced stages of the disease, alcoholism, adverse reactions to drugs as a cause of withdrawal from treatment, and other current diseases at the time of tuberculosis diagnosis.