Residential exposure to traffic pollution and mammographic density in premenopausal women.

BACKGROUND: Mammographic density (MD) is the most important breast cancer biomarker. Ambient pollution is a carcinogen, and its relationship with MD is unclear. This study aims to explore the association between exposure to traffic pollution and MD in premenopausal women. METHODOLOGY: This Spanish cross-sectional study involved 769 women attending gynecological examinations in Madrid. Annual Average Daily Traffic (AADT), extracted from 1944 measurement road points provided by the City Council of Madrid, was weighted by distances (d) between road points and women's addresses to develop a Weighted Traffic Exposure Index (WTEI). Three methods were employed: method-1 (1dAADT), method-2 (1dAADT), and method-3 (e1dAADT). Multiple linear regression models, considering both log-transformed percentage of MD and untransformed MD, were used to estimate MD differences by WTEI quartiles, through two strategies: "exposed (exposure buffers between 50 and 200 m) vs. not exposed (>200 m)"; and "degree of traffic exposure". RESULTS: Results showed no association between MD and traffic pollution according to buffers of exposure to the WTEI (first strategy) for the three methods. The highest reductions in MD, although not statistically significant, were detected in the quartile with the highest traffic exposure. For instance, method-3 revealed a suggestive inverse trend (eßQ1 = 1.23, eßQ2 = 0.96, eßQ3 = 0.85, eßQ4 = 0.85, p-trend = 0.099) in the case of 75 m buffer. Similar non-statistically significant trends were observed with Methods-1 and -2. When we examined the effect of traffic exposure considering all the 1944 measurement road points in every participant (second strategy), results showed no association for any of the three methods. A slightly decreased MD, although not significant, was observed only in the quartile with the highest traffic exposure: eßQ4 = 0.98 (method-1), and eßQ4 = 0.95 (methods-2 and -3). CONCLUSIONS: Our results showed no association between exposure to traffic pollution and MD in premenopausal women. Further research is needed to validate these findings.

The Detection of SARS-CoV-2 Antibodies in an Exposed Human Population Is Biased by the Immunoassay Used: Implications in Serosurveillance.

The presence of SARS-CoV-2 antibodies was examined over 7 months in a population of essential service workers exposed during the first epidemic wave in Madrid (Spain). Results obtained with different serological assays were compared. Firstly, serum samples obtained in April 2020 were analyzed using eleven SARS-CoV-2 antibody detection methods, including seven ELISAs, two CLIAs and two LFAs. While all of the ELISA tests and the Roche eCLIA method showed good performance, it was poorer for the Abbott CLIA and LFA tests. Sera from 115 workers with serologically positive results in April were collected 2 and 7 months after the first sampling and were analyzed using five of the tests previously assessed. The results showed that while some ELISA tests consistently detected the presence of anti-SARS-CoV-2 antibodies even 7 months after first detection, other methods, such as the Abbott CLIA test, showed an important reduction in sensitivity for these mature antibodies. The sensitivity increased after establishing new cut-off values, calculated taking into account both recent and old infections, suggesting that an adjustment of assay parameters may improve the detection of individuals exposed to the infection.

Mammographic density in the environs of multiple industrial sources.

BACKGROUND: Mammographic density (MD), defined as the percentage of dense fibroglandular tissue in the breast, is a modifiable marker of the risk of developing breast cancer. Our objective was to evaluate the effect of residential proximity to an increasing number of industrial sources in MD. METHODS: A cross-sectional study was conducted on 1225 premenopausal women participating in the DDM-Madrid study. We calculated distances between women's houses and industries. The association between MD and proximity to an increasing number of industrial facilities and industrial clusters was explored using multiple linear regression models. RESULTS: We found a positive linear trend between MD and proximity to an increasing number of industrial sources for all industries, at distances of 1.5 km (p-trend = 0.055) and 2 km (p-trend = 0.083). Moreover, 62 specific industrial clusters were analyzed, highlighting the significant associations found between MD and proximity to the following 6 industrial clusters: cluster 10 and women living at ≤1.5 km (ß = 10.78, 95 % confidence interval (95%CI) = 1.59; 19.97) and at ≤2 km (ß = 7.96, 95%CI = 0.21; 15.70); cluster 18 and women residing at ≤3 km (ß = 8.48, 95%CI = 0.01; 16.96); cluster 19 and women living at ≤3 km (ß = 15.72, 95%CI = 1.96; 29.49); cluster 20 and women living at ≤3 km (ß = 16.95, 95%CI = 2.90; 31.00); cluster 48 and women residing at ≤3 km (ß = 15.86, 95%CI = 3.95; 27.77); and cluster 52 and women living at ≤2.5 km (ß = 11.09, 95%CI = 0.12; 22.05). These clusters include the following industrial activities: surface treatment of metals/plastic, surface treatment using organic solvents, production/processing of metals, recycling of animal waste, hazardous waste, urban waste-water treatment plants, inorganic chemical industry, cement and lime, galvanization, and food/beverage sector. CONCLUSIONS: Our results suggest that women living in the proximity to an increasing number of industrial sources and those near certain types of industrial clusters have higher MD.

Sociodemographic and Lifestyle Determinants of Adherence to Current Dietary Recommendations and Diet Quality in Middle-Aged Spanish Premenopausal Women.

Background: A healthy diet when approaching menopause could prevent some of the symptoms associated with the climacteric. Few studies examine adherence to current healthy dietary recommendations in middle-aged premenopausal women. Our objective was to analyze the diet quality and the adherence to the Spanish Society of Community Nutrition (SENC) dietary recommendations in middle-aged Spanish premenopausal women, and to identify the associated sociodemographic and lifestyle factors. Methods: This is a cross-sectional study based on 1251 premenopausal women, aged 39-50, who attended to Madrid City Council Medical Diagnostic Center. Women completed an epidemiological and a food frequency questionnaire. Degree of adherence to the SENC recommendations was estimated with a score that evaluated null (0 points) and full (1 point) adherence of each specific recommendation. Associations were explored using an ordinal logistic multivariable regression model. Results: Regarding food groups, the worst adherence was found for sweets, red/processed meat, olive oil and eggs. Most of the participants exceeded the recommended caloric intake from proteins and fats, and practically all of them showed vitamin D intake deficiency. The overall score ranged from 2 to 12 (out of 15), with a median of 6.0 (interquartile range: 5.0-7.0). Former smokers (OR: 1.38; 95%CI: 1.08-1.78), as well as those with higher educational level (ORSSecondary:1.68; 95%CI: 0.97-2.93, ORUniversity:1.82; 95%IC: 1.05-3.14), with two or more children (OR: 1.31; 95%IC: 1.00-1.72), with higher caloric intake (OR>2188.2kcal/day: 8.22; 95%CI: 6.19-10.92) and with greater physical activity (OR≥21METS-h/week: 1.29; 95%CI: 0.95-1.76) showed greater adherence. Conclusions: Almost two-thirds of middle-aged premenopausal participants showed low or moderate compliance with SENC recommendations. Education, smoking, parity, and physical activity were associated with the degree of adherence to these recommendations.

Residential proximity to industrial pollution and mammographic density.

BACKGROUND: Mammographic density (MD), expressed as percentage of fibroglandular breast tissue, is an important risk factor for breast cancer. Our objective is to investigate the relationship between MD and residential proximity to pollutant industries in premenopausal Spanish women. METHODS: A cross-sectional study was carried out in a sample of 1225 women extracted from the DDM-Madrid study. Multiple linear regression models were used to assess the association of MD percentage (and their 95% confidence intervals (95%CIs)) and proximity (between 1 km and 3 km) to industries included in the European Pollutant Release and Transfer Register. RESULTS: Although no association was found between MD and distance to all industries as a whole, several industrial sectors showed significant association for some distances: "surface treatment of metals and plastic" (ß = 4.98, 95%CI = (0.85; 9.12) at ≤1.5 km, and ß = 3.00, 95%CI = (0.26; 5.73) at ≤2.5 km), "organic chemical industry" (ß = 6.73, 95%CI = (0.50; 12.97) at ≤1.5 km), "pharmaceutical products" (ß = 4.14, 95%CI = (0.58; 7.70) at ≤2 km; ß = 3.55, 95%CI = (0.49; 6.60) at ≤2.5 km; and ß = 3.11, 95%CI = (0.20; 6.01) at ≤3 km), and "urban waste-water treatment plants" (ß = 8.06, 95%CI = (0.82; 15.30) at ≤1 km; ß = 5.28; 95%CI = (0.49; 10.06) at ≤1.5 km; ß = 4.30, 95%CI = (0.03; 8.57) at ≤2 km; ß = 5.26, 95%CI = (1.83; 8.68) at ≤2.5 km; and ß = 3.19, 95%CI = (0.46; 5.92) at ≤3 km). Moreover, significant increased MD was observed in women close to industries releasing specific pollutants: ammonia (ß = 4.55, 95%CI = (0.26; 8.83) at ≤1.5 km; and ß = 3.81, 95%CI = (0.49; 7.14) at ≤2 km), dichloromethane (ß = 3.86, 95%CI = (0.00; 7.71) at ≤2 km), ethylbenzene (ß = 8.96, 95%CI = (0.57; 17.35) at ≤3 km), and phenols (ß = 2.60, 95%CI = (0.21; 5.00) at ≤2.5 km). CONCLUSIONS: Our results suggest no statistically significant relationship between MD and proximity to industries as a whole, although we detected associations with various industrial sectors and some specific pollutants, which suggests that MD could have a mediating role in breast carcinogenesis.

SARS-CoV-2 surveillance strategy in essential workers of the Madrid City Council during the first epidemic wave in Spain, March-July 2020.

OBJECTIVES: To study prevalence of infection in essential workers of Madrid City Council by occupation, related characteristics, use of protective devices, risk perception, and main concerns about COVID-19 during lockdown. METHODS: A total of 30 231 workers were PCR tested for SARS-CoV-2 infection. Information was collected on COVID-19-related symptoms, risk factors, preventive equipment, and risk perception. The crude prevalence was calculated for infection, use of protective devices, perceived risk and main concerns. Additionally, adjusted prevalence and prevalence ratios (PR) were estimated for these variables using logistic regression models with age, gender, occupation, epidemiological week and laboratory as confounding factors. RESULTS: Overall prevalence of infection was 3.2% (95% CI 3.0% to 3.4%), being higher among policemen (4.4%) and bus drivers (4.2%), but lower among emergency healthcare personnel, firefighters, food market workers and burial services (<2%). Lower excess risk was observed in workers reporting occupational contact with COVID-19 cases only (PR=1.42; 95% CI 1.18 to 1.71) compared with household exposure only (PR=2.75; 95% CI 2.32 to 3.25). Infection was more frequent in symptomatic workers (PR=1.28; 95% CI 1.11 to 1.48), although 42% of detected infections were asymptomatic. Use of facial masks (78.7%) and disinfectants (86.3%) was common and associated with lower infection prevalence (PRmasks=0.68; 95% CI 0.58 to 0.79; PRdisinfectants=0.75; 95% CI 0.61 to 0.91). Over 50% of workers felt being at high risk of infection and worried about infecting others, yet only 2% considered quitting their work. CONCLUSIONS: This surveillance system allowed for detecting and isolating SARS-CoV-2 cases among essential workers, identifying characteristics related to infection and use of protective devices, and revealing specific needs for work-safety information and psychological support.

Factors Associated with Serum Vitamin D Metabolites and Vitamin D Metabolite Ratios in Premenopausal Women.

The most representative indicator of vitamin D status in clinical practice is 25(OH)D3, but new biomarkers could improve the assessment of vitamin D status and metabolism. The objective of this study is to investigate the association of serum vitamin D metabolites and vitamin D metabolite ratios (VMRs) with potentially influential factors in premenopausal women. This is a cross-sectional study based on 1422 women, aged 39-50, recruited from a Madrid Medical Diagnostic Center. Participants answered an epidemiological and a food frequency questionnaire. Serum vitamin D metabolites were determined using an SPE-LC-MS/MS platform. The association between participant's characteristics, vitamin D metabolites, and VMRs was quantified by multiple linear regression models. Mean 25(OH)D3 concentration was 49.2 + 18.9 nmol/L, with greater deficits among obese, nulliparous, dark-skinned women, and with less sun exposure. A lower R2 ratio (1,25(OH)2D3/25(OH)D3) and a higher R4 (24,25(OH)2D3/1,25(OH)2D3) were observed in nulliparous women, with high sun exposure, and those with low caloric intake or high consumption of calcium, vitamin D supplements, or alcohol. Nulliparous women had lower R1 (25(OH)D3/Vit D3) and R3 (24,25(OH)2D3/25(OH)D3), and older women showed lower R3 and R4. Vitamin D status modified the association of the VMRs with seasons. VMRs can be complementary indicators of vitamin D status and its endogenous metabolism, and reveal the influence of certain individual characteristics on the expression of hydroxylase enzymes.

The C-Terminal Half of SARS-CoV-2 Nucleocapsid Protein, Industrially Produced in Plants, Is Valid as Antigen in COVID-19 Serological Tests.

BACKGROUND: The fight against the current coronavirus disease 2019 (COVID-19) pandemic has created a huge demand of biotechnological, pharmaceutical, research and sanitary materials at unprecedented scales. One of the most urgent demands affects the diagnostic tests. The growing need for rapid and accurate laboratory diagnostic tests requires the development of biotechnological processes aimed at producing reagents able to cope with this demand in a scalable, cost-effective manner, with rapid turnaround times. This is particularly applicable to the antigens employed in serological tests. Recombinant protein expression using plants as biofactories is particularly suitable for mass production of protein antigens useful in serological diagnosis, with a neat advantage in economic terms. METHODS: We expressed a large portion of the nucleoprotein (N) derived from SARS-CoV-2 in Nicotiana benthamiana plants. After purification, the recombinant N protein obtained was used to develop an indirect enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to SARS-CoV-2 in human sera. To validate the ELISA, a panel of 416 sera from exposed personnel at essential services in Madrid City Council were tested, and the results compared to those obtained by another ELISA, already validated, used as reference. Furthermore, a subset of samples for which RT-PCR results were available were used to confirm sensitivity and specificity of the test. RESULTS: The performance of the N protein expressed in plants as antigen in serologic test for SARS-CoV-2 antibody detection was shown to be highly satisfactory, with calculated diagnostic sensitivity of 96.41% (95% CI: 93.05-98.44) and diagnostic specificity of 96.37 (95% CI: 93.05-98.44) as compared to the reference ELISA, with a kappa (K) value of 0.928 (95% CI:0.892-0.964). Furthermore, the ELISA developed with plant-derived N antigen detected SARS-CoV-2 antibodies in 84 out of 93 sera from individuals showing RT-PCR positive results (86/93 for the reference ELISA). CONCLUSION: This study demonstrates that the N protein part derived from SARS-CoV-2 expressed in plants performs as a perfectly valid antigen for use in COVID-19 diagnosis. Furthermore, our results support the use of this plant platform for expression of recombinant proteins as reagents for COVID-19 diagnosis. This platform stands out as a convenient and advantageous production system, fit-for-purpose to cope with the current demand of this type of biologicals in a cost-effective manner, making diagnostic kits more affordable.

Occupation, occupational exposures and mammographic density in Spanish women.

INTRODUCTION: Mammographic density (MD), the proportion of radiologically dense breast tissue, is a strong risk factor for breast cancer. Our objective is to investigate the influence of occupations and occupational exposure to physical, chemical, and microbiological agents on MD in Spanish premenopausal women. METHODS: This is a cross-sectional study based on 1362 premenopausal workers, aged 39-50, who attended a gynecological screening in a breast radiodiagnosis unit of Madrid City Council. The work history was compiled through a personal interview. Exposure to occupational agents was evaluated using the Spanish job-exposure matrix MatEmESp. MD percentage was assessed using the validated semi-automated computer tool DM-Scan. The association between occupation, occupational exposures, and MD was quantified using multiple linear regression models, adjusted for age, educational level, body mass index, parity, previous breast biopsies, family history of breast cancer, energy intake, use of oral contraceptives, smoking, and alcohol consumption. RESULTS: Although no occupation was statistically significantly associated with MD, a borderline significant inverse association was mainly observed in orchard, greenhouse, nursery, and garden workers (ß = -6.60; 95% confidence interval (95%CI) = -14.27; 1.07) and information and communication technology technicians (ß = -7.27; 95%CI = -15.37; 0.84). On the contrary, a positive association was found among technicians in art galleries, museums, and libraries (ß = 8.47; 95%CI = -0.65; 17.60). Women occupationally exposed to fungicides, herbicides, and insecticides tended to have lower MD. The percentage of density decreased by almost 2% for every 5 years spent in occupations exposed to the mentioned agents. CONCLUSIONS: Although our findings point to a lack of association with the occupations and exposures analyzed, this study supports a deeper exploration of the role of certain occupational agents in MD, such as pesticides.

Serum 25-hydroxyvitamin D and mammographic density in premenopausal Spanish women.

The role of vitamin D in mammographic density is still unclear. This study examines the association between serum 25-hydroxyvitamin D (25(OH)D) and mammographic density, overall and by specific women characteristics. DDM-Madrid is a cross-sectional study that recruited 1403 premenopausal women in a breast radiodiagnosis unit of Madrid City Council. Information was collected with a questionnaire and plasma 25(OH)D was measured by solid-phase extraction on-line coupled to liquid chromatography-tandem mass spectrometry. Percent mammographic density was assessed using a semi-automated computer tool (DM-Scan). Multivariable linear regression models were used to quantify the associations, categorizing 25(OH)D levels (nmol/L) into 3 groups according to the cut-offs established by the US Endocrine Society. Models were adjusted for age, education, body mass index, age at menarche, parity, previous breast biopsies, family history of breast cancer, physical activity, energy intake, use of corticoids, hypercholesterolemia and day of sample extraction. Mean serum 25(OH)D level was 49.4 + 18.9 nmol/L. Women with sufficient concentrations of 25(OH)D showed a slight decrease in mammographic density (ß >75nmol/L=-3.40; p = 0.037). No differences were observed according to women characteristics except for parity, where the protective effect of 25(OH)D was only seen among nulliparous (ß >75nmol/L=-13.00; p-heterogeneity = 0.006). In light of the protective effect of vitamin D on mammographic density and the high prevalence of vitamin D insufficiency in our population, improving these levels could be an effective measure for the prevention of health problems related to the lack of this essential vitamin.

Factores asociados al sobrepeso, la obesidad general y la obesidad abdominal en la población adulta de la Comunidad de Madrid, Spain. Estudio PREDIMERC / Factors associated with overweight, general obesity and abdominal obesity in the Madrid Community's adult population. Study PREDIMERC

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Prevalencia de diabetes mellitus y factores de riesgo cardiovascular en la población adulta de la Comunidad de Madrid: estudio PREDIMERC / Prevalence of diabetes mellitus and cardiovascular risk factors in the adult population of the autonomous region of Madrid (Spain): the PREDIMERC study

ObjetivoDeterminar la prevalencia de diabetes y los principales factores de riesgo cardiovascular en la población adulta de la Comunidad de Madrid.Material y métodoEstudio transversal de base poblacional en el año 2007. Se seleccionó una muestra aleatoria representativa de la población de 30–74 años, con un tamaño muestral fijo para cada estrato de edad, ponderando los resultados según la estructura por edad de la Comunidad de Madrid. Se realizó una encuesta telefónica. Posteriormente, en el centro de salud se efectuó la exploración física y la extracción de sangre en ayunas para determinar la glucemia, el colesterol y las fracciones lipídicas.ResultadosSe incluyeron 2.268 personas con una edad media de 48,3 años; el 52% eran mujeres. La tasa de respuesta fue del 56,4%. El 8,1% (intervalo de confianza del 95% [IC95%]: 7,0–8,9) de la población presenta diabetes y el 5,9% (IC95%: 4,8–6,1) una glucemia basal alterada. El 29,3% (IC95%: 27,3–31,5) tiene hipertensión arterial y el 23,3% (IC 95%: 21,4–25,2) hipercolesterolemia. El 22,8% (IC95%: 20,8–25,0) presenta sobrepeso de grado II, el 21,7% (IC95%: 19,8–23,6) obesidad y el 23,9% (IC95%: 21,8–26,1) obesidad abdominal. El 85,5% (IC95%: 83,1–87,1) eran sedentarios en tiempo libre y el 28,4% (IC95%: 26,3–30,3) fumadores.ConclusionesLa prevalencia de diabetes mellitus en la Comunidad de Madrid se sitúa en una posición intermedia con respecto a otras comunidades autónomas. Los principales factores de riesgo cardiovascular tienen una elevada prevalencia. El sobrepeso de grado II y la obesidad, que afectan a 4,5 de cada 10 adultos, representan una prioridad de intervención en la prevención de la diabetes y la enfermedad cardiovascular(AU)

ObjectiveTo describe the prevalence of diabetes and major cardiovascular risk factors in the adult population of the autonomous region of Madrid (Spain).Material and methodA population-based cross-sectional study was carried out in 2007. A random sample of the population aged 30–74 years old was selected. A fixed sample size per age stratum was assigned, weighted by the real age-specific distribution of the population of the autonomous region of Madrid. An epidemiological survey was conducted by telephone. Subsequently, physical examination was performed and a fasting blood sample was taken in the health center for glucose, cholesterol and lipid fraction determinations.ResultsWe included 2268 people with a mean age of 48.3 years old (52% women). The response rate was 56.4%. Diabetes was found in 8.1% (95%CI: 7.0–8.9) of the adult population and impaired fasting glucose was found in 5.9% (95%CI: 4.8–6.1). The prevalence of risk factors was as follows: hypertension in 29.3% (95%CI: 27.3–31.5), hypercholesterolemia in 23.3% (95%CI: 21.8–26.1), overweight grade II in 22.8% (20.8–25.0), obesity in 21.7% (95%CI: 19.8–23.6), and central obesity in 23.9% (95%CI: 21.8–26.1). A total of 85.5% (95%CI: 83.1–87.1) were sedentary in their leisure time and 28.4% (95%CI: 26.3–30.3) were smokers.ConclusionsThe prevalence of diabetes in the autonomous region of Madrid is intermediate in relation to other regions of Spain. Cardiovascular risk factors are highly prevalent, and are higher in men than in women. Overweight and obesity, affecting 4.5 out of every 10 adults, should be considered a priority for health interventions in cardiovascular disease prevention(AU)

[Prevalence of diabetes mellitus and cardiovascular risk factors in the adult population of the autonomous region of Madrid (Spain): the PREDIMERC study]. / Prevalencia de diabetes mellitus y factores de riesgo cardiovascular en la población adulta de la Comunidad de Madrid: estudio PREDIMERC.

OBJECTIVE: To describe the prevalence of diabetes and major cardiovascular risk factors in the adult population of the autonomous region of Madrid (Spain). MATERIAL AND METHOD: A population-based cross-sectional study was carried out in 2007. A random sample of the population aged 30-74 years old was selected. A fixed sample size per age stratum was assigned, weighted by the real age-specific distribution of the population of the autonomous region of Madrid. An epidemiological survey was conducted by telephone. Subsequently, physical examination was performed and a fasting blood sample was taken in the health center for glucose, cholesterol and lipid fraction determinations. RESULTS: We included 2268 people with a mean age of 48.3 years old (52% women). The response rate was 56.4%. Diabetes was found in 8.1% (95%CI: 7.0-8.9) of the adult population and impaired fasting glucose was found in 5.9% (95%CI: 4.8-6.1). The prevalence of risk factors was as follows: hypertension in 29.3% (95%CI: 27.3-31.5), hypercholesterolemia in 23.3% (95%CI: 21.8-26.1), overweight grade II in 22.8% (20.8-25.0), obesity in 21.7% (95%CI: 19.8-23.6), and central obesity in 23.9% (95%CI: 21.8-26.1). A total of 85.5% (95%CI: 83.1-87.1) were sedentary in their leisure time and 28.4% (95%CI: 26.3-30.3) were smokers. CONCLUSIONS: The prevalence of diabetes in the autonomous region of Madrid is intermediate in relation to other regions of Spain. Cardiovascular risk factors are highly prevalent, and are higher in men than in women. Overweight and obesity, affecting 4.5 out of every 10 adults, should be considered a priority for health interventions in cardiovascular disease prevention.

Nivel de arsénico en abastecimientos de agua de consumo de origen subterráneo en la Comunidad de Madrid / Arsenic evels in drinking water supplies from underground sources in the autonomous community of Madrid

Fundamento: En 1998 se detectaron en la Comunidad de Madrid concentraciones de arsénico mayores de 50mµg/l en algunos abastecimientos de agua de consumo de origen subterráneo, concentración máxima admisible en el agua de bebida en España. El objetivo de este trabajo fue determinar la concentración de arsénico en el agua procedente de abastecimientos subterráneos en la Comunidad de Madrid. Métodos: Se presentan los resultados de los dos primeros muestreos realizados en el plan de seguimiento de niveles de arsénico establecido. En la primera fase se analizaron muestras de agua de los 353 abastecimientos censados por la Dirección General de Salud Pública de la Comunidad de Madrid. Con estos primeros resultados se realizó una clasificación de riesgo de los abastecimientos. En una segunda fase, seis meses después, se repitieron los análisis en los 35 abastecimientos que se consideró podían suponer un riesgo para la salud pública. Resultados: El 74 por ciento de los abastecimientos estudiados en la primera fase presentaron una concentración de arsénico menor de 10mµg/l.; el 22,6 por ciento contenía niveles entre 10 y 50µg/l.; y en el 3,7 por ciento eran superiores a 50m µg/l.. La mayoría de los abastecimientos con niveles de arsénico superiores a 10m µg/l. se encuentran situados en la misma zona geográfica. En el segundo muestreo (6 meses después) se incluyeron los 35 abastecimientos clasificados de riesgo. De ellos, 26 presentaron el mismo nivel de arsénico (10-50µg/l.) y 9 cambiaron de categoría: 6 pasaron a tener menos de 10m µg/l. y 3 más de 50m µg/l.. Conclusiones: La vigilancia periódica de la calidad del agua realizada por la Dirección General de Salud Pública ha permitido detectar la presencia de 16 abastecimientos de agua de consumo de origen subterráneo con más de 50m µg/l. de arsénico, nivel máximo admisible según la legislación vigente en nuestro país. Se han adoptado medidas para evitar el consumo de agua en estos abastecimientos (AU)

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