Carlos Santos-Burgoa

Use of lead‐glazed ceramics is the main factor associated to high lead in blood levels in two Mexican rural communities

Two isolated rural communities of Mexico were studied to assess the possible relationship between lead-glazed ceramics use and lead exposure. Women from these communities (n = 98) were asked to participate by filling out a general-purpose and exposure questionnaire in order to assess the individual contribution of ceramics to lead exposure. Blood samples were withdrawn to measure lead in blood and erythrocytic zinc protoporphyrin levels. Results were analyzed by multiple regression in order to find predictors of the dependent variables. Significant association between lead in blood and erythrocytic zinc protoporphyrin levels was identified with the following variables: storage in lead-glazed ceramics, cooking in lead-glazed ceramics, and meat and cheese consumption. The adjusted regression models explained 20-23% of the variance of the dependent variables (lead in blood and erythrocytic zinc protoporphyrin). A significant association (r2 = .38) was observed between lead in blood and lead in food prepared in lead-glazed ceramics in a subsample of 28 women. Results indicate that lead-glazed ceramics use may be the main predictor of lead in blood and erythrocytic zinc protoporphyrin levels in the rural communities studied.

Household Firewood Use and the Health of Children and Women of Indian Communities in Chiapas, Mexico

Abstract 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 μm in diameter was significantly lower in households with the better stoves in the kitchen area, where children usually play, i.e., 158 μg/m3 vs 305 μg/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; 95% 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.

Personal PM2.5 and CO exposures and heart rate variability in subjects with known ischemic heart disease in Mexico City.

Cardiovascular diseases are the main cause of death in Mexico City and have shown a rising trend over the past 20 years. Various epidemiological studies have reported an association between respirable particles and carbon monoxide (CO), with cardiorespiratory outcomes. The purpose of this study was to assess the effect of particulate matter with aerodynamic diameters of less than 2.5 μm (PM2.5), also known as respirable or fine particles and CO on heart rate variability (HRV) in 5-min periods in patients with known ischemic heart disease. 30 patients were selected from the outpatient clinic of the National Institute of Cardiology of Mexico and followed during 11 h, using electrocardiography (ECG) ambulatory electrocardiograms and personal monitors for CO and PM2.5. We calculated frequency-domain measurements using power spectral analysis and assessed the association with pollutants using mixed models analysis in 5-min periods. We found a decrease in HRV measured as high frequency (Ln) (coefficient=−0.008, 95% confidence interval (CI), −0.015, 0.0004) for each 10 μg/m3 (micrograms per cubic meter) increase of personal PM2.5 exposure. We also found a decrease of low (ln) (coefficient=−0.024, 95% CI, −0.041, −0.007) and very low frequencies (ln) (coefficient=−0.034, 95% CI, −0.061, −0.007) for 1 parts per million (p.p.m.) increase in CO personal exposure after adjustment for potential confounding factors. These results show that for this high-risk population, the alteration of the cardiac autonomic regulation was significantly associated with both PM2.5 and CO personal exposures.

Common vampire bat attacks on humans in a village of the Amazon region of Brazil

Many people in Amazonian communities have reported bat bites in the last decade. Bites by vampire bats can potentially transmit rabies to humans. The objective of this study was to analyze factors associated with bat biting in one of these communities. A cross-sectional survey was conducted in a village of gold miners in the Amazonian region of Brazil (160 inhabitants). Bats were captured near peoples houses and sent to a lab. Of 129 people interviewed, 41% had been attacked by a bat at least once, with 92% of the bites located on the lower limbs. A logistic regression found that adults were bitten around four times more often than children (OR = 3.75, CI 95%: 1.46-9.62, p = 0.036). Males were bitten more frequently than females (OR = 2.08, CI 95%: 0.90-4.76, p = 0.067). Nine Desmodus rotundus and three frugivorous bats were captured and tested negative for rabies. The study suggests that, in an area of gold miners, common vampire bats are more likely to attack adults and males. The control strategy for human rabies developed in this region should therefore place special emphasis on adult males. There should also be more research on how the search for gold in the Amazonian region places people and the environment at risk.

Lymphohematopoietic cancers and butadiene and styrene exposure in synthetic rubber manufacture.

The described nested case-control study of lymphohematopoietic cancers occurring in a cohort of synthetic rubber production workers was conducted to determine the associations of these cancers with exposure to butadiene and styrene. Cases have been confirmed through hospital record review of 95 percent of the cancers. Exposures are based on measured values of the two chemicals from personal monitoring data in seven of the eight plants under study. The results indicate that the risk of leukemia increases with exposure to a time-weighted average butadiene measure. The odds ratio at only 1 ppm average butadiene exposure is 1.50 (95% CI 1.07, 2.10). Work in specific areas also contributes to the risk, possibly because these areas have not been completely characterized for differences in butadiene exposure. Hodgkins disease is also associated with butadiene exposure. Multiple myeloma, lymphosarcoma, and all lymphomas are associated with exposure to styrene. Since workers in this industry are apparently exposed to two carcinogenic agents, further effort must be made to distinguish the exposures to each chemical over time and to characterize their interrelationship with the risk of cancers of the lymphohematopoietic system.

Developing consensus: mercury science and policy in the NAFTA countries (Canada, the United States and Mexico)

The international science community has recognized methylmercury in the aquatic food chain, as a potential environmental and human health risk. As a result, countries around the world have implemented a number of mercury management initiatives. The United States, Mexico and Canada in consultation with stakeholders are developing a trilateral North American Regional Action Plan (NARAP) on mercury. Through public involvement in the decision making process, the NARAP has offered opportunities for more transparency in transactions between governments, industry and stakeholders. In spite of the available scientific information, there are still important uncertainties associated with the mercury issue. These knowledge gaps include: the most appropriate methylmercury reference dose for sensitive groups; the percentage of the North American population that is at risk from methylmercury exposure; spatial and temporal mercury deposition patterns in each country; the link between mercury emissions, atmospheric deposition and methylmercury concentrations in fish; and the relative magnitude of contributions from natural and anthropogenic sources.

Occurrence of airborne enteric bacteria in Mexico city

SummaryAn investigation of microbial air quality in the area of the National Autonomous University of Mexico, located in the southern part of Mexico City, was conducted for one year. Ambient outdoor concentrations and size distribution of airborne bacteria were measured, 130 samples were taken at noon, using an Andersen 6 stage sampler, located 2 m above ground level. Concentration ranges and colony-forming units per cubic meter of air (CFU m−3) found, were as follows:14 to 12999 for total bacteria, No growth (NG) to 55 for coliform bacteria, NG to 11 for fecal coliform and NG to 10 for fecal Streptococci.Bacteria associated with the potentially respirable fraction (0.65 to 4.7 µm) averaged 37% and 9% for total bacteria and coliform bacteria respectively. In 23% of the samples, coliform bacteria were recovered, with higher incidences during dry season. The most common of these were:Escherichia coli (15%), followed bySerratia (13%) andEnterobacter (10%),The total bacteria correlated significatively (p<0.05) with the following parameters: particulate matter smaller than 10 µm (PM10) (r=0.40), total suspended particulates (TSP) (r=0.26), daily variation of temperature (r=0.18), and vapor pressure (r=−0.16). These relationships indicate that fecal soil pollution could affect air quality with potential health risks.

Tratamiento contra la rabia humana: un poco de su historia

A historical review of the treatment of human rabies from ancient times up to the present is undertaken. An attempt is made to trace parallel between the concept of the main cause of rabies in a certain period and the kind of treatment utilized. The ancient Greek goddess Artemis was considered to be a healer of rabies; they already identified wound cauterization. People of the first century A.D. knew of the infection deriving from the saliva of a rabid dog and called it virus (in Latin). During medieval times when a magical and religious concept regarding health was prevalent, the principal protector was called St. Humbert. During the Renaissance many experiments were carried out and new information on the disease was obtained, both were basic in opening the way for new findings in the future. At that time the miasmatic and contagious theories were predominant. Pasteur strongly objected to the idea of the spontaneity of rabies. At the end of the XIXth. century and based on microbial discoveries, Pasteur brought about a great scientific revolution as regards the possibility of treating rabies by using a vaccine. At the present time, vaccines are of the nervous type or not, and the recommended dose varies. A large-number of studies on vaccination have been undertaken. In Latin America the most used are those by Fuenzalida and Palacios. At present, WHO recommends the vaccine made by cell culture.

Prevalencia de la pérdida auditiva y factores correlacionados en una industria cementera

Objective. To assess the impact of occupational exposure to noise, as well as its relationship with other factors that can induce hearing loss. Material and methods. In January and February 1997, we conducted sonometry and dosimetry tests in a cement factory, as well as audiometric test in 85 cement workers, to identify sources of noise and evaluate the effect to noise exposure and other factors, of the prevalence of occupational hearing loss. Statistical analysis was conducted using measures of central tendency, bivariate analysis and polynominal regression models. Results. High noise levels were found in the crushing, crude milling, and cement milling sites. The highest individual dose corresponded to the packer job post. Fifty-five per cent of the study population presented some degree of hearing loss due to noise exposure. The cement processing area with the highest percentage of damaged workers was calcination. Conclusions. Our results show that noise is a serious risk factor in particular sites of cement factories, and also that an elevated number of hearing loss cases are due to occupational noise exposure in this industry; Our findings underscore the need for designing and implementing hearing protection programs, to assure the health and safety of cement workers.

The present and future of Mexican health promotion

Mexico, with a 92 percent literacy, 62 native languages and 12.7 million indigenous people, has entered a new era of macroeconomic stability. Nevertheless 40 percent of the population live below the poverty line. The burden of disease includes malnutrition, infectious diseases, reproductive health problems, as well as chronic diseases. Addressing the social determinants of health has been a priority. This can be seen in two of the most successful Mexican programs. The National Healthy Communities Program that uses a setting approach to establish a link between socioeconomic development and health levels and the Opportunities Program that has become an international model and which is a comprehensive, poverty alleviation program that uses education, fiscal measures and health education to improve population health. Both have been implemented throughout all the states in an intersectorial manner, since 1997 and 2000 respectively. Health promotion in Mexico has evolved in many positive ways during the past 20 years. Development of healthy environments and community actions are the strongest components. Evidence and evaluation, health services reorientation, and building personal skills and empowerment are the weakest. The paradox between low empowerment and high community action results in a superficial community participation that lacks a real commitment towards health. The newest Mexican health promotion policy is named National Alliance for Health and it aims to involve all members of society. Its value is to be independent of any international recommendation; its weakness is that it lacks a deep analysis of the health issues that it is supposed to solve. Consequently valid evaluations are not feasible, and without real evidence the impact of these kinds of policies will remain unknown. (Promotion & Education, 2007, XIV (4): pp 224-227)