Enrique Cifuentes

Methylmercury exposure in a subsistence fishing community in Lake Chapala, Mexico: an ecological approach

BackgroundElevated concentrations of mercury have been documented in fish in Lake Chapala in central Mexico, an area that is home to a large subsistence fishing community. However, neither the extent of human mercury exposure nor its sources and routes have been elucidated.MethodsTotal mercury concentrations were measured in samples of fish from Lake Chapala; in sections of sediment cores from the delta of Rio Lerma, the major tributary to the lake; and in a series of suspended-particle samples collected at sites from the mouth of the Lerma to mid-Lake. A cross-sectional survey of 92 women ranging in age from 18-45 years was conducted in three communities along the Lake to investigate the relationship between fish consumption and hair mercury concentrations among women of child-bearing age.ResultsHighest concentrations of mercury in fish samples were found in carp (mean 0.87 ppm). Sediment data suggest a pattern of moderate ongoing contamination. Analyses of particles filtered from the water column showed highest concentrations of mercury near the mouth of the Lerma. In the human study, 27.2% of women had >1 ppm hair mercury. On multivariable analysis, carp consumption and consumption of fish purchased or captured from Lake Chapala were both associated with significantly higher mean hair mercury concentrations.ConclusionsOur preliminary data indicate that, despite a moderate level of contamination in recent sediments and suspended particulate matter, carp in Lake Chapala contain mercury concentrations of concern for local fish consumers. Consumption of carp appears to contribute significantly to body burden in this population. Further studies of the consequences of prenatal exposure for child neurodevelopment are being initiated.

Dengue Fever Seroprevalence and Risk Factors, Texas-Mexico Border, 2004

High seroprevalence of dengue was found on both sides of the border.

Assessing the roles of temperature, precipitation, and enso in dengue re-emergence on the Texas-Mexico border region

OBJECTIVE The goal of this study was to assess linkages between microclimate and longer-term ENSO-related weather forcing on the week-to-week changes in dengue prevalence in Matamoros, Tamaulipas, Mexico, over a recent decade of dengue observations. MATERIAL AND METHODS An auto-regressive model to evaluate the role of climatic factors (sea-surface temperature) and weather (maximum temperature, minimum temperature, precipitation) on dengue incidence over the period 1995-2005, was developed by conducting time-series analysis. RESULTS Dengue incidence increased by 2.6% (95% CI: 0.2-5.1) one week after every 1 degree Celsius increase in weekly maximum temperature and increased 1.9% (95% CI: -0.1-3.9) two weeks after every 1 cm increase in weekly precipitation. Every 1 masculineC increase in sea surface temperatures (El Niño region 3.4 ) was followed by a 19.4% (95% CI: -4.7-43.5) increase in dengue incidence (18 weeks later). CONCLUSIONS Climate and weather factors play a small but significant role in dengue transmission in Matamoros, Mexico. This study may provide baseline information for identifying potential longer-term effects of global climate change on dengue expected in the coming decades. To our knowledge, this is the first study to investigate the potential associations between climate and weather events and dengue incidence in this geographical area.

Environmental impact of wastewater irrigation in central Mexico: an overview

The current knowledge on the environmental impact and public health risks associated with wastewater irrigation in central Mexico is summarized and discussed. Wastewater reuse in that semiarid region represents a valuable resource in agricultural production, due to the irrigation supply and considerable nutrients input to the farming soil. Nevertheless, there is evidence of increased prevalence of parasitic infections among agricultural workers and their families exposed to raw wastewater irrigation. Negative environmental effects may result from long‐term wastewater application, due to heavy metal accumulation in soils, increasing amounts of immediately mobile and easily mobilizable metal fractions, as well as crops uptake. First investigations carried out on soil fertility suggest the occurrence of important nitrogen losses, which could represent potential risks to public health induced by elevated nitrate concentrations in groundwater. Emphasis is given on future research priorities and measures that h...

The epidemiology of enteric infections in agricultural communities exposed to wastewater irrigation: Perspectives for risk control

A cross-sectional survey was carried out in the irrigation districts of central Mexico, in which 9435 individuals participated. The health outcomes included diarrhoeal diseases and Ascaris lumbricoides infection. Water quality was assessed using faecal coliforms (FC) and nematode eggs as indicators of faecal pollution. Exposure groups were: 848 households irrigating with untreated wastewater; 544 households irrigating with the effluent from a series of interconnected reservoirs; and 928 households farming with natural rainfall. Children from households irrigating with untreated wastewater (108 FC/100 mL and 125 nematode eggs/L) had a 33% higher risk of diarrhoeal diseases than children from rainfall villages (OR = 1.33), whereas children from households exposed to the reservoirs effluent were not different from those in the rainfall group (OR = 1.17). No excess risk was found in older individuals from different exposure groups, but males had a 50% higher risk of disease than females (OR = 1.50). In the fi...

The risk of Ascaris lumbricoides infection in children as an environmental health indicator to guide preventive activities in Caparaó and Alto Caparaó, Brazil

OBJECTIVE To develop an environmental health indicator for use as a basis for developing preventive measures against Ascaris lumbricoides infection in children from the rural municipalities of Caparaó and Alto Caparaó, in Minas Gerais, Brazil. METHODS A cross-sectional survey was conducted between May and September 1998 among 1171 children under 14 years of age living in 588 dwellings selected from 11 communities. Trained interviewers used a questionnaire to identify risk factors for infection (socioeconomic, sanitation and hygiene variables) and collected stool samples from each child for parasitological tests. RESULTS The overall prevalence of A. lumbricoides infection was 12.2%. The results showed the protective effects of availability of water in the washbasin and better hygiene, sanitation and socioeconomic status; the interactive effect of crowding was five times larger in households without water in the washbasin than in those having water. There was a statistically significant association between infection and childrens age. CONCLUSION The environmental health indicator, which incorporated the most significant biological, environmental and social factors associated with the risk of A. lumbricoides infection in children from these communities, should contribute to the development of surveillance tools and health protection measures in this population.

The risk of enteric diseases in young children and environmental indicators in sentinel areas of Mexico City

The overall objective of this study is to promote the development of environmental health indicators in Mexico City. Specific examples focused on water quality, household characteristics e.g., sanitation and risk of enteric diseases. A geographic information system (GIS) was used in order to identify eligible wells and their surrounding homesteads (0.5 km around each well). A pilot study was conducted during the rainy season (1999), and a total of 1, 250 eligible households were visited on a random sample basis; only those having children under 5 years of age were interviewed. Data on diarrheal disease (i.e. occurrence in the previous two weeks) were obtained from 950 children, and their guardians provided information on their water supply, sanitation and socioeconomic variables. A total of 320 water samples were obtained from 40 wells, and tested for Total coliforms (TC/100 ml), Fecal coliforms (FC/100 ml). Escherichia coli (EC) and Fecal streptococci (FS). Bacterial indicators were detected in 40% of the wells in the western zone and in 32% of the southern zone (p = 0.01). The rate of diarrheal diseases was higher for children from the southern areas than in the west (OR = 1.7 and 95% CI: 0.99, 2.86). The final analysis showed a higher risk of diarrhea in children from rented homes than those living in owned dwellings (OR = 1.7 and 95% Cl: 1.04, 2.77): the risk was also highest for children living in houses with poor sanitation facilities (e.g., latrine) than those connected to a sewerage (OR = 1.7 and 95% Cl: 1.00, 2.93). Children from households perceiving unpleasant taste of water showed a higher risk than those without complaints (OR = 2.2 and 95% Cl: 1.28, 3.75). Linkages between environmental factors and health risk were created from spatially distributed information, and the proposed environmental health indicator ( EHI ) summarized the most significant predictors of diarrheal diseases. This baseline information may contribute to further environmental health investigation and policy making analysis.

Limiting the consumption of sugar sweetened beverages in Mexico's obesogenic environment: a qualitative policy review and stakeholder analysis.

Mexico is building a legal framework to address its childhood obesity epidemic. Sugar sweetened beverages (SSB) in the school environment represent a major policy challenge. We addressed the following questions: What barriers inhibit political attention to SSB and childhood obesity? What political instruments, international and national, exist to guide agenda setting in Mexico? What opportunities exist for policy adoption? We conducted a systematic review of international and national legal instruments concerned with SSB consumption. We traced process, conducting interviews with key informants. Thematic analysis helped us identify barriers and opportunities for public health interventions. We found 11 national policy instruments, but detected implementation gaps and weak fiscal policies on SSB consumption in schools: limited drinking water infrastructure, SSB industry interests, and regulatory ambiguities addressing reduction of sugar in beverages. Public policy should target marketing practices and taxation. The school environment remains a promising target for policy. Access to safe drinking water must complement comprehensive and multi-sector policy approaches to reduce access to SSB.

A qualitative analysis of environmental policy and children's health in Mexico

BackgroundSince Mexicos joining the North American Free Trade Agreement (NAFTA) and the Organization for Economic Cooperation and Development (OECD) in 1994, it has witnessed rapid industrialization. A byproduct of this industrialization is increasing population exposure to environmental pollutants, of which some have been associated with childhood disease. We therefore identified and assessed the adequacy of existing international and Mexican governance instruments and policy tools to protect children from environmental hazards.MethodsWe first systematically reviewed PubMed, the Mexican legal code and the websites of the United Nations, World Health Organization, NAFTA and OECD as of July 2007 to identify the relevant governance instruments, and analyzed the approach these instruments took to preventing childhood diseases of environmental origin. Secondly, we interviewed a purposive sample of high-level government officials, researchers and non-governmental organization representatives, to identify their opinions and attitudes towards childrens environmental health and potential barriers to child-specific protective legislation and implementation.ResultsWe identified only one policy tool describing specific measures to reduce developmental neurotoxicity and other childrens health effects from lead. Other governance instruments mention childrens unique vulnerability to ozone, particulate matter and carbon monoxide, but do not provide further details. Most interviewees were aware of Mexican environmental policy tools addressing childrens health needs, but agreed that, with few exceptions, environmental policies do not address the specific health needs of children and pregnant women. Interviewees also cited state centralization of power, communication barriers and political resistance as reasons for the absence of a strong regulatory platform.ConclusionsThe Mexican government has not sufficiently accounted for childrens unique vulnerability to environmental contaminants. If regulation and legislation are not updated and implemented to protect children, increases in preventable exposures to toxic chemicals in the environment may ensue.

Development of the Pediatric Environmental Health Specialty Unit Network in North America

Training in environmental health in general, and pediatric environmental health in particular, is inadequate. The Agency for Toxic Substances and Disease Registry began to develop pediatric environmental health specialty units (PEHSUs) after noting the dearth of practitioners who could evaluate and manage children with exposures to environmental health hazards. The Environmental Protection Agency subsequently joined in providing support for what has developed into a network of 13 PEHSUs in North America. PEHSUs provide services to families, act as consultants to clinicians and public agencies, develop educational materials, and respond to natural disasters, including hurricanes and wildfires. PEHSUs are relatively easy to organize and should be replicable internationally.