Analytical performance specifications for trace elements in biological fluids derived from six countries federated external quality assessment schemes over 10 years.

OBJECTIVES: This article defines analytical performance specifications (APS) for evaluating laboratory proficiency through an external quality assessment scheme. METHODS: Standard deviations for proficiency assessment were derived from Thompson's characteristic function applied to robust data calculated from participants' submissions in the Occupational and Environmental Laboratory Medicine (OELM) external quality assurance scheme for trace elements in serum, whole blood and urine. Characteristic function was based on two parameters: (1) ß - the average coefficient of variation (CV) at high sample concentrations; (2) α - the average standard deviation (SD) at low sample concentrations. APSs were defined as 1.65 standard deviations calculated by Thompson's approach. Comparison between OELM robust data and characteristic function were used to validate the model. RESULTS: Application of the characteristic function allowed calculated APS for 18 elements across three matrices. Some limitations were noted, particularly for elements (1) with no sample concentrations near analytical technique limit of detection; (2) exhibiting high robust CV at high concentration; (3) exhibiting high analytical variability such as whole blood Tl and urine Pb; (4) with an unbalanced number of robust SD above and under the characteristic function such as whole blood Mn and serum Al and Zn. CONCLUSIONS: The characteristic function was a useful means of deriving APS for trace elements in biological fluids where biological variation data or outcome studies were not available. However, OELM external quality assurance scheme data suggests that the characteristic functions are not appropriate for all elements.

Minerals and trace elements in pregnancy in women with previous bariatric surgery consequences on maternal and foetal health.

BACKGROUND: Bariatric surgery (BS) may decrease the risk of these obesity-related complications; however, due to its effect on nutrient intake and absorption, it can also have adverse consequences on maternal and foetal health. The aim of this study is to describe the evolution of electrolytes and trace elements serum levels throughout pregnancy after BS, according to the surgical technique and to evaluate the effect of nutritional deficiencies on the risk of maternal-foetal complications. METHODS: This is a retrospective observational study of the clinical evolution and maternal-foetal complications in a group of women with pregnancies that occurred after BS. Clinical evolution during pregnancy, body weight, and plasma electrolytes, vitamins, and trace elements, as well as their influence on maternal-foetal outcomes were evaluated. Composite neonatal variable (CNV) was defined to evaluate unfavourable foetal outcome. Published reference values for micronutrients during pregnancy have been used. RESULTS: The study includes data on 164 singleton pregnancies in 91 women. A hundred and twenty-seven pregnancies got to full term. The average birth weight was 2966 (546) g., 26.8% < P10 and 13.8% < P3 of a reference population. New-born of gestations after malabsorptive bariatric surgery had a higher risk of having a percentile of birth weight < P3. Plasma electrolytes, trace elements and vitamins throughout pregnancy showed differences depending on the surgical technique, with lower haemoglobin, ferritin, calcium, zinc, copper, vitamin A and vitamin E in the malabsorptive techniques. A high percentage of deficiency was observed, especially in the third trimester (Hb < 11 g/dl: 31.8%; ferritin < 30 mg/ml: 85.7%; zinc < 50 µg/dl: 32.4%, vitamin D < 30 ng/ml: 75.5% and < 20 ng/ml: 53.3%). A decreased plasma copper in the first trimester or zinc in the third trimester were associated with a lower percentile of new-born birth weight. A higher risk of CNV was observed in predominant malabsorptive BS and in pregnancies that had presented at least one vitamin D level lower than 20 ng/ml throughout pregnancy (30.4% vs. 7.1%, p=0.018). CONCLUSIONS: Trace elements and vitamin deficiencies are common in pregnant women after bariatric surgery, especially of iron, zinc, and vitamin D. These deficiencies might negatively affect foetal development. Further studies are needed to better define the role of micronutrients in maternal-foetal health after bariatric surgery.

Are lead, cadmium and mercury risk factors for resistant hypertension?

BACKGROUND: Lead (Pb), cadmium (Cd) and mercury (Hg) are toxic trace elements that represent a public health problem as risk factors for cardiovascular disease and hypertension (HT) and could also contribute to the development of resistant hypertension (rHT) AIMS: To compare the blood concentrations of Pb, Cd and Hg in subjects with resistant and non-resistant HT and to define whether there is a relationship between its levels and rHT. METHODS: Cross-sectional study. Subjects aged ≥ 21 to ≤ 80 years with a body mass index < 40 kg/m2 were recruited on a discretionary basis from October 2001 to October 2004 in a hypertension unit of a tertiary hospital amongst those sent to the hypertension unit by their family physician. Resistant hypertension was defined according to the American Heart Association (AHA) criteria. Whole blood concentrations of Cd, Pb and Hg were measured by electrothermal atomic absorption spectrometry. RESULTS: 46 out of 73 included subjects (63%) suffered from rHT. Blood Pb median: HT 3.9 (IQR 2.7-5.2) vs. rHT 3.6 (IQR 2.8-6.0) µg/dL (p=0.941). Blood Cd median: HT 0.07 (IQR 0.07-0.80) vs. rHT 0.30 (IQR 0.07-0.65) µg/L (p=0.681). Blood Hg median: HT 7.9 (IQR 5.8-12.9) vs. rHT 7.3 (IQR 4.6-13.3) µg/L (p=0.611). Considering the 75th percentile of each element (Pb: 5.55 µg/dL, Cd: 0.75 µg/L, Hg: 13.15 µg/L), a multiple logistic regression analysis (adjusted for age, BMI, diabetes mellitus, clearance of creatinine and only for Cd the smoking habit) showed an OR = 3.44 (0.84-14.10, p=0.086) for Pb, OR = 1.80 (0.39-8.24, p=0.451), for Cd and OR = 2.31 (0.59-9.14, p=0.232) for Hg. Moreover, the stratified analyses showed that men with Pb ≥5.55 µg/dL have a 14 times higher risk of suffering from rHT (p=0.026). Interestingly, a 9-fold increased risk was found for non-obese subjects with elevated Pb levels, above 5.55 µg/dL (p=0.029). Also in men, the probability of suffering from rHT was more than 7 times higher if Cd levels were ≥ 0.75 µg/L (p=0.076). Most smokers had higher Cd levels, with a high risk of suffering from rHT (ORa 12.6 (0.8-200.2), p=0.072). CONCLUSION: A higher blood Pb levels, defined by the 75th percentile (Pb ≥ 5.55 µg/dL), is associated with a greater risk of suffering from rHT and to a lesser extent in the case of Cd and Hg.

The cardiomyopathy of cystic fibrosis: a modern form of Keshan disease.

Introduction: We conducted a study to determine the prevalence of structural heart disease in patients with CF, the characteristics of a cardiomyopathy not previously described in this population, and its possible relationship with nutritional deficiencies in CF. Methods: We studied 3 CMP CF patients referred for heart-lung transplantation and a prospective series of 120 adult CF patients. All patients underwent a clinical examination, blood tests including levels of vitamins and trace elements, and echocardiography with evaluation of myocardial strain. Cardiac magnetic resonance imaging (CMR) was performed in patients with CMP and in a control group. Histopathological study was performed on hearts obtained in transplant or necropsy. Results: We found a prevalence of 10% (CI 4.6%-15.4%) of left ventricular (LV) dysfunction in the prospective cohort. Myocardial strain parameters were already altered in CF patients with otherwise normal hearts. Histopathological examination of 4 hearts from CF CMP patients showed a unique histological pattern of multifocal myocardial fibrosis similar to Keshan disease. Four of the five CF CMP patients undergoing CMR showed late gadolinium uptake, with a characteristic patchy pattern in 3 cases (p < 0.001 vs. CF controls). Selenium deficiency (Se < 60 µg/L) was associated with more severe LV dysfunction, higher prevalence of CF CMP, higher NTproBNP levels, and more severe pulmonary and digestive involvement. Conclusion: 10% of adults with CF showed significant cardiac involvement, with histological and imaging features resembling Keshan disease. Selenium deficiency was associated with the presence and severity of LV dysfunction in these patients.

Iron, vitamins and minerals status in pediatric patients with celiac diseaseand non celiac gluten sensitivity prior to diagnosis and three months later.

AIM: Pathologies associated with gluten intake are increasingly prevalent. Diagnosis of celiac disease (CD) or non-celiac gluten sensitivity (NCGS) is based on compatible clinical alterations and in case of CD on compatible serology or intestinal biopsy. The aim was to determine the values of iron, vitamins and minerals prior to diagnosis and to verify whether a gluten-free diet treatment can cause the normalization of these parameters both in patients diagnosed with celiac disease and gluten sensitivity. METHODS: Retrospective observational study from November 2016 to November 2021. 101 celiac patients and 26 with NCGS were included, all under 18 years of age. Levels of Fe, Na+ , K+ , Cl-, Ferritin, Ca2 + , P, Vitamin B12, Vitamin D and Transferrin were determined, following the quality standards of the Hospital Clínico San Carlos laboratory. Statistical software IBM SPSS Statistics v.26 was used. RESULTS: Calcium levels in celiac patients follow a positive trend after 3 months of gluten-free diet. Ferritin levels in patients with NCGS increased in a statistically significant way (p < 0.017). CONCLUSION: Calcium in the CD group increases its values after the establishment of a gluten-free diet as treatment, as well as ferritin in patients with NCGS. No significant changes were found in the rest of the analyzed parameters. This could be due to the precocity of the diagnosis thanks to a rapid clinical suspicion that determines few analytical alterations.

Viral RNA load in plasma is associated with critical illness and a dysregulated host response in COVID-19.

BACKGROUND: COVID-19 can course with respiratory and extrapulmonary disease. SARS-CoV-2 RNA is detected in respiratory samples but also in blood, stool and urine. Severe COVID-19 is characterized by a dysregulated host response to this virus. We studied whether viral RNAemia or viral RNA load in plasma is associated with severe COVID-19 and also to this dysregulated response. METHODS: A total of 250 patients with COVID-19 were recruited (50 outpatients, 100 hospitalized ward patients and 100 critically ill). Viral RNA detection and quantification in plasma was performed using droplet digital PCR, targeting the N1 and N2 regions of the SARS-CoV-2 nucleoprotein gene. The association between SARS-CoV-2 RNAemia and viral RNA load in plasma with severity was evaluated by multivariate logistic regression. Correlations between viral RNA load and biomarkers evidencing dysregulation of host response were evaluated by calculating the Spearman correlation coefficients. RESULTS: The frequency of viral RNAemia was higher in the critically ill patients (78%) compared to ward patients (27%) and outpatients (2%) (p < 0.001). Critical patients had higher viral RNA loads in plasma than non-critically ill patients, with non-survivors showing the highest values. When outpatients and ward patients were compared, viral RNAemia did not show significant associations in the multivariate analysis. In contrast, when ward patients were compared with ICU patients, both viral RNAemia and viral RNA load in plasma were associated with critical illness (OR [CI 95%], p): RNAemia (3.92 [1.183-12.968], 0.025), viral RNA load (N1) (1.962 [1.244-3.096], 0.004); viral RNA load (N2) (2.229 [1.382-3.595], 0.001). Viral RNA load in plasma correlated with higher levels of chemokines (CXCL10, CCL2), biomarkers indicative of a systemic inflammatory response (IL-6, CRP, ferritin), activation of NK cells (IL-15), endothelial dysfunction (VCAM-1, angiopoietin-2, ICAM-1), coagulation activation (D-Dimer and INR), tissue damage (LDH, GPT), neutrophil response (neutrophils counts, myeloperoxidase, GM-CSF) and immunodepression (PD-L1, IL-10, lymphopenia and monocytopenia). CONCLUSIONS: SARS-CoV-2 RNAemia and viral RNA load in plasma are associated with critical illness in COVID-19. Viral RNA load in plasma correlates with key signatures of dysregulated host responses, suggesting a major role of uncontrolled viral replication in the pathogenesis of this disease.

External quality assessment schemes for inorganic elements in the clinical laboratory: Lessons from the OELM scheme.

Measurements of inorganic elements in clinical laboratories produce results used for the diagnosis, the treatment and the monitoring of deficiencies or overloads. The main objective of External Quality Assessment Schemes is to verify, on a regular frequency, that clinical laboratory results correspond to the quality requirement for patient care. Therefore, External Quality Assessment Schemes represent an essential component of a laboratory's quality management system. However, External Quality Assessment Schemes within the same analytical field remain heterogeneous for different reasons such as samples, determination of assigned value, acceptable limits, content of the reports. The aim of this review was to describe and illustrate some major critical aspects of External Quality Assessment Schemes based on Occupational and Environmental Laboratory Medicine external quality assessment scheme experience.

Blood lead in children and associations with trace elements and sociodemographic factors.

BACKGROUND: No safe blood lead concentration in children has been identified. Lead can affect nearly every system in the body and is especially harmful to the developing central nervous system of children. The aim of this study is to analyze blood lead in a population of children and its association with sociodemographic variables, biochemical parameters, copper, iron, selenium and zinc. METHODS: We recruited 155 children (86 boys and 69 girls) with a mean age of 7.3 (SD:4.1). Blood lead and serum selenium concentrations were measured by electrothermal atomic absorption spectrometry. Serum copper and zinc concentrations were measured by flame atomic absorption spectrometry. Serum iron levels were determined by colorimetric assay. A risk exposure questionnaire for lead was administered to the participants. RESULTS: The median blood lead level was 1.1 (IQR 0.7-1.6) µg/dL. Regarding risk exposure factors, the youngest children (<2 years) who played outdoors presented a median blood lead concentration of 1.1 µg/dL IQR: 0.48-1.48, compared to the median of 0.3 µg/dL IQR:0.2-0.48 in the children who stated they played at home (p = 0.024). Significant differences were also found when taking into account those parents who smoked (median 1.3 IQR 0.8-1.9 µg/dL vs 0.9 IQR 0.5-1.4 µg/dL of non-smokers, p = 0.002). Children who drank tap water had higher blood lead levels (median 1.2 IQR 0.7-1.6 µg/dL) than those who drank bottled water (median 0.7 IQR 0.2-1.3 µg/dL p = 0.014). In addition, children whose mothers had not finished school had higher blood lead levels (median 1.7 IQR 1.2-2.3 µg/dL) than those whose mothers had finished school (median 1.2 IQR 0.7-1.7 µg/dL) and those whose mothers had gone to university (median 0.9 IQR 0.5-1.4 µg/dL) p = 0.034. In the multivariate lineal regression analysis we continue to observe the association between mother's higher level of education and lower blood levels (p = 0.04) and the interaction between age and outdoor play (p = 0.0145). CONCLUSIONS: In spite of the decline in blood lead concentrations, associated risk factors continue to exist in vulnerable populations such as children.

Relationship between serum selenium, sociodemographic variables, other trace elements and lipid profile in an adult Spanish population.

INTRODUCTION: Several studies have shown an inverse relationship between selenium status and cardiovascular health, although epidemiologic evidence yielded by the randomized trials did not find a beneficial effect of selenium administration. The aim of this study was to analyze the association between serum selenium levels and lipid profile adjusted by age, sex and other associated factors among a general adult population in Spain. MATERIALS AND METHODS: We recruited 372 hospital employee volunteers (60 men and 312 women) with a mean age of 47 (SD: 10.9), whom were given a standardized questionnaire. Serum selenium concentration was measured by electrothermal atomization atomic absorption spectrometry. Serum copper and zinc concentrations were measured using flame atomic absorption spectrometry. RESULTS: The mean of serum selenium was 79.5µg/L (SD: 11.7) with no sex-dependent differences. In the multivariate linear regression analysis, the associated factors with the mean levels of selenium were: age (ß=0.223; CI 95%: 0.101-0.345), p<0.001; widowhood (ß=-9.668; CI 95%: -17.234 to -2.102), p=0.012; calcium supplements (ß=3.949; CI 95%: 0.059-7.838), p=0.047; zinc (ß=0.126; CI 95%: 0.013-0.238), p=0.028 and glucose (ß=0.172; CI 95%: 0.062- 0.281), p=0.002; Participants with serum selenium≥79.5µg/L were 1.98 (OR=1.98; CI 95% 1.17-3.35; p=0.011) and 2.04 times (OR=2.04; CI 95% 1.06-3.97; p=0.034) more likely to have cholesterol ≥200mg/dL and LDL-c ≥100mg/dL respectively than those with serum selenium <79.5µg/L. CONCLUSIONS: Higher selenium was positively associated with increased total and LDL cholesterol but not with HDL-c and triglycerides. More studies are needed in order to confirm the lower serum selenium findings in widows.

Probabilistic risk analysis of mercury intake via food consumption in Spain.

In Spain, recently, the public institutions have given information to the population in relation to fish consumption and the risk that it poses to health from the ingestion of mercury supposedly contained in the fish. At the same time, several scientific societies have published various works in this direction. All this without there being, up to now, any study on the evaluation of a probabilistic risk from mercury due to fish and seafood intake in Spain, which is the objective of this present work. For that purpose, we took individual data from a survey of the total diet of 3000 people, whose consumption of the principal fish and seafood species (49) was estimated. We compiled individualized data (2000) on the total mercury content of those species, which were completed and validated with bibliographic statistical data. After estimating the distributions of each fish and seafood species, both of their consumption and their mercury content, a simulation was made of the distribution of mercury ingestion from fish and seafood offered by 2.6% of the Spanish population at risk of exceeding total mercury recommendations, and between 12.2% and 21.2% of those exceeding methylmercury ones. The main species responsible were tuna fish, swordfish and hake, and significant differences were identified in fish consumption between sexes and ages, although, in the risk percentage, what stands out is an increase in the latter with an increase in age.

[Economic Appraisal of the Impact of the Ban on the Use of Lead in Gasoline on the Intellectual Quotient of 7-8 Years Old in the Community of Madrid]. / Evaluación económica del impacto de la prohibición de plomo en las gasolinas en el cociente intelectual de los niños de 7 y 8 años de la Comunidad de Madrid.

BACKGROUND: The repercussions on health of public policies are hard to assess from an economic point of view, which is why this is rarely done. The purpose of this study was to financially quantify the benefits of reducing blood lead levels in children aged 7-8 years in the Community of Madrid (Spain) as a result of the ban on the use of lead in gasoline. METHODS: The decrease the intellectual quotient (IQ) points was calculated through two studies on children aged 7-8 years according to their blood lead levels. A geometric mean of 3.8 µg/dl was obtained in the 1995 study and of 0.9 µg/dl in the 2010 study. The net increase in IQ was measured in terms of productivity gained throughout the working life as per the methods of Schwartz and Salkever. RESULTS: The decrease in blood lead levels in these children prevented a loss of between 135,391 and 144,153 IQ points; the current economic valuation of these points in terms of the productivity gained throughout the working life of this cohort of children was estimated to fall within the €626.4m- €865.4m range (2009). CONCLUSIONS: The figures of the economic benefits derived from the decision to ban leaded gasoline are very high.

Consensus document on the prevention of methylmercury exposure in Spain: Study group for the prevention of Me-Hg exposure in Spain (GEPREM-Hg).

The beneficial effects of fish consumption in both children and adults are well known. However, the intake of methylmercury, mainly from contaminated fish and shellfish, can have adverse health effects. The study group on the prevention of exposure to methylmercury (GEPREM-Hg), made up of representatives from different Spanish scientific societies, has prepared a consensus document in a question and answer format, containing the group's main conclusions, recommendations and proposals. The objective of the document is to provide broader knowledge of factors associated with methylmercury exposure, its possible effects on health amongst the Spanish population, methods of analysis, interpretation of the results and economic costs, and to then set recommendations for fish and shellfish consumption. The group sees the merit of all initiatives aimed at reducing or prohibiting the use of mercury as well as the need to be aware of the results of contaminant analyses performed on fish and shellfish marketed in Spain. In addition, the group believes that biomonitoring systems should be set up in order to follow the evolution of methylmercury exposure in children and adults and perform studies designed to learn more about the possible health effects of concentrations found in the Spanish population, taking into account the lifestyle, eating patterns and the Mediterranean diet.

[Methylmercury exposure in the general population; toxicokinetics; differences by gender, nutritional and genetic factors]. / Exposición al metilmercurio en la población general; toxicocinética; diferencias según el sexo, factores nutricionales y genéticos.

Mercury is an environmental toxicant that causes numerous adverse effects on human health and natural ecosystems. The factors that determine the existance of adverse effects, as well as their severity are, among others: the chemical form of mercury (elemental, inorganic, organic), dosis, age, period of exposure, pathways of exposure and environmental, nutritional and genetic factors. In the aquatic cycle of mercury, once it has been deposited, it is transformed into methylmercury due to the action of certain sulphate-reducing bacteria, which bioaccumulates in the aquatic organisms and moves into the food chain. The methylmercury content of large, long-lived fish such as swordfish, shark, tuna or marlin, is higher. Methylmercury binds to protein in fish and is therefore not eliminated by cleaning or cooking the fish. Fetuses and small children are more vulnerable to the neurotoxic effects of methylmercury from the consumption of contaminated fish. Methylmercury is absorbed in the gastrointestinal tract and crosses the blood-brain barrier and the placenta. The intake of certain dietary components such as polyunsaturated fatty acids, selenium, fiber, thiol compounds, certain phytochemicals and other nutrients can modify methylmercury bioaccesibility and its toxicity. Apart from environmental factors, genetic factors can influence mercury toxicity and explain part of the individual vulnerability.

El mercurio es un tóxico ambiental que causa numerosos efectos adversos en la salud humana y en los ecosistemas naturales. Los factores que determinan la aparición de efectos adversos y su severidad son entre otros: la forma química del mercurio (elemental, inorgánico, orgánico), la dosis, la edad, la duración de la exposición, la vía de exposición y los factores ambientales, nutricionales y genéticos. En el ciclo acuático del mercurio, una vez que se ha depositado, se transforma en metilmercurio por la acción de determinadas bacterias sulfato reductoras y se bioacumula en los organismos acuáticos incorporándose a la cadena trófica de alimentos. El contenido de metilmercurio es mayor en las especies depredadoras de mayor tamaño y que viven más años como el emperador, pez espada, tiburón, atún o marlín. El metilmercurio se halla unido a las proteínas del pescado por lo que no se elimina mediante la limpieza ni el cocinado del mismo. El feto en desarrollo y los niños pequeños son los más vulnerables a los efectos neurotóxicos del metilmercurio procedente de la ingesta de pescado contaminado. El metilmercurio se absorbe en el tracto gastrointestinal y atraviesa la barrera hematoencefálica y la placenta. Algunos componentes de la dieta como los ácidos grasos poliinsaturados, el selenio, la fibra, los compuestos tiol, algunos fitoquímicos y otros nutrientes pueden modificar la bioaccesibilidad del mercurio y su toxicidad. Además de los factores ambientales, los factores genéticos pueden influir en la toxicidad del mercurio y explicar parte de la vulnerabilidad individual.

[The effects of methylmercury on health in children and adults; national and international studies]. / Efectos sobre la salud del metilmercurio en niños y adultos; estudios nacionales e internacionales.

The benefit of fish consumption in children and adults is well-known. However, it has been pointed out that excessive methylmercury intake due to consumption of contaminated fish leads to neurological toxicity in children, affecting cognitive function, memory, visual-motor function and language. After the intoxications in Minamata and Iraq, wide-ranging epidemiological studies were carried out in New Zealand, the Faroe Islands and the Seychelles and international recommendations were established for fish consumption in pregnant women and small children. In Spain, the Childhood and Environmental project (INMA, its Spanish acronym) has studied the effects of diet and the environment on fetal and childhood development in different geographic areas of Spain. National and international sudies have demonstrated that mercury concentrations are mainly dependent on fish consumption, although there are variations among countries which can be explained not only by the levels of fish consumption, but also by the type or species of fish that is consumed, as well as other factors. Although the best documented adverse effects of methylmercury are the effects on nervous sytem development in fetuses and newborns, an increasing number of studies indicate that cognitive function, reproduction and, especially, cardiovascular risk in the adult population can also be affected. However, more studies are necessary in order to confirm this and establish the existance of a causal relationship.

Los efectos beneficiosos del consumo de pescado tanto en niños como en adultos han sido bien reconocidos. Sin embargo, se ha referido que la ingesta excesiva de metilmercurio procedente del pescado contaminado produce toxicidad neurológica en los niños afectando a la función cognitiva, la memoria, la función visual-motora y al lenguaje. Después de las intoxicaciones de Minamata e Iraq, se realizaron grandes estudios epidemiológicos en Nueva Zelanda, las islas Féroe y las islas Seychelles y se establecieron recomendaciones internacionales sobre el consumo de pescado y marisco en las mujeres embarazadas y niños pequeños. En España, el proyecto Infancia y Medio Ambiente (INMA) ha estudiado los efectos del medio ambiente y de la dieta sobre el desarrollo fetal e infantil en diversas zonas geográficas de España. Los estudios realizados nacionales e internacionales muestran que la concentración de mercurio depende principalmente del consumo de pescado, aunque existe una variabilidad entre los países que podría explicarse no solo por la cantidad de pescado consumida, sino también por el tipo o especies de pescados que se consumen, así como por otro tipo de factores. Aunque los efectos perjudiciales del metilmercurio mejor documentados son los que se producen sobre el desarrollo del sistema nervioso en el feto y en el recién nacido, cada vez hay más estudios que indican que también puede afectar a la función cognitiva, reproducción y especialmente al riesgo cardiovascular en la población adulta. Sin embargo, son necesarios más estudios para confirmarlo y establecer la existencia de una relación causal.

[Methylmercury: existing recommendations; methods of analysing and interpreting the results; economic evaluation]. / Metilmercurio: recomendaciones existentes; métodos de análisis e interpretación de resultados; evaluación económica.

The beneficial effects of fish consumption are well- known. Nevertheless, there is worldwide concern regard methylmercury concentrations in fish, which is why many countries such as the United States, Australia, New Zealand, Canada and numerous European countries have made fish consumption recommendations for their populations, particularly vulnerable groups, in order to México methylmercury intake. Blood and hair are the best biological samples for measuring methylmercury. The most widely-used method to analyse methylmercury is cold vapor atomic absorption spectrometry, although there are also direct methods based on the thermal decomposition of the sample. In recent years, the number of laboratories that measure mercury by inductively coupled plasma mass spectrometry has increased. In addition, the different kinds of mercury can be distinguished by coupling chromatography methods of separation. Laboratories that analyse mercury in biological samples need to participate in external quality control programmes. Even if mercury emissions are reduced, mercury may remain in the environment for many years, so dietary recommendations are fundamental in order to reduce exposure. It is necessary to propose public health measures aimed at decreasing mercury exposure and to evaluate the benefits of such measures from the economic and social standpoints.

Los efectos beneficiosos del consumo de pescado son bien reconocidos. Sin embargo, existe preocupación a nivel mundial sobre los niveles de metilmercurio en el pescado, por lo que muchos países como Estados Unidos, Australia, Nueza Zelanda, Canadá y muchos países europeos han realizado recomendaciones de consumo de pescado a la población , especialmente a los grupos vulnerables con el fin de reducir la ingesta de metilmercurio. La sangre y el pelo son las mejores muestras biológicas para medir el metilmercurio. El método de análisis más empleado ha sido la espectroscopia de absorción atómica con la técnica del vapor frío, aunque existen también métodos directos que se basan en la descomposición térmica de la muestra. En los últimos años han aumentado los laboratorios que miden el mercurio por espectrometría de masas con plasma acoplado por inducción. Además, se puede diferenciar las distintas especies de mercurio acoplando métodos de separación cromatográficos. Es necesario que los laboratorios que analizan mercurio en muestras biológicas participen en programas de garantía externa de la calidad. Aunque se logre reducir las emisiones de mercurio, el mercurio del medio ambiente todavía puede permanecer muchos años, por lo que es fundamental el consejo dietético para disminuir la exposición. No es aconsejable el uso de terapia quelante con fines diagnósticos o en pacientes asintomáticos. Es preciso proponer medidas de salud pública encaminadas a la disminución de la exposición al mercurio y que se evalúe también los beneficios de las mismas desde el punto de vista económico y social.

[Consensus document on the prevention of exposure to methylmercury in Spain]. / Documento de consenso sobre la prevención de la exposición al metilmercurio en España.

The beneficial effects of fish consumption in both children and adults are well known. However, the intake of methylmercury, mainly from contaminated fish and shellfish, can have adverse health effects. The study group on the prevention of exposure to methylmercury (GEPREM-Hg), made up of representatives from different Spanish scientific societies, has prepared a consensus document in a question and answer format, containing the group's main conclusions, recommendations and proposals. The objective of the document is to provide broader knowledge of factors associated with methylmercury exposure, its possible effects on health among the Spanish population, methods of analysis, interpretation of the results and economic costs, and to then set recommendations for fish and shellfish consumption. The group sees the merit of all initiatives aimed at reducing or prohibiting the use of mercury as well as the need to be aware of the results of contaminant analyses performed on fish and shellfish marketed in Spain. In addition, the group believes that biomonitoring systems should be set up in order to follow the evolution of methylmercury exposure in children and adults and perform studies designed to learn more about the possible health effects of concentrations found in the Spanish population, ta king into account the lifestyle, eating patterns and the Mediterranean diet.

Los efectos beneficiosos del consumo de pescado tanto en niños como en adultos han sido bien reconocidos. Sin embargo, la ingesta de metilmercurio principalmente a través del pescado y marisco contaminado puede producir efectos adversos en la salud. El grupo de estudio para la prevención de la exposición al metilmercurio (GEPREM-Hg), constituido por representantes de diferentes sociedades científicas españolas, ha elaborado un documento de consenso donde se recogen en forma de preguntas y respuestas las principales conclusiones, recomendaciones y propuestas planteadas en el grupo. El objetivo del documento es profundizar en el conocimiento de los factores asociados a la exposición al metilmercurio, los posibles efectos sobre la salud en la población española, los métodos de análisis, la interpretación de los resultados, el coste económico y establecer finalmente recomendaciones de consumo de pescados y mariscos. El grupo considera acertadas todas las iniciativas encaminadas a reducir o prohibir el uso del mercurio y la necesidad de conocer los resultados de los análisis de contaminantes que se realizan en los pescados y mariscos que se comercializan en España. Además, opina que se deberían establecer sistemas de biomonitorización para conocer la evolución de la exposición al metilmercurio en niños y adultos y realizar estudios diseñados para conocer los posibles efectos sobre la salud de las concentraciones halladas en la población española, teniendo en cuenta el estilo de vida, los patrones de consumo alimentarios y la dieta mediterránea.

Trace elements in bipolar disorder.

INTRODUCTION: Trace elements may play an important role in bipolar disorders. The objective of this study is to determine serum copper and zinc, blood lead and cadmium and urine lead, cadmium and thallium concentrations in patients diagnosed with bipolar disorders and to compare these levels with those of a healthy control group. MATERIALS AND METHODS: A total of 25 patients diagnosed with bipolar disorder and 29 healthy subjects participated in this study. Serum copper and zinc concentrations were measured using flame atomic absorption spectrometry; the blood lead and cadmium concentrations were measured by electrothermal atomization atomic absorption spectrometry with Zeeman background correction; urine lead, cadmium and thallium concentrations were measured by inductively coupled plasma mass spectrometry. RESULTS: Median blood and urine lead and cadmium levels were significantly higher among the bipolar patients than among the control group: Blood lead (µg/dL): patient median: 3.00 (IQR: 1.40-4.20); control median (µg/dL): 2.20 (IQR: 0.90-3.00) p=0.040. Blood cadmium (µg/L): patient median: 0.39 (IQR: 0.10-1.15); control median: 0.10 (IQR: 0.10-0.17) p<0.001. The median of cadmium (µg/L) in patients who smoked (1.20 IQR: 0.44-2.30) was higher than that in non-smokers (0.12 IQR: 0.10-0.34) p<0.001. There was a statistically significant increase (p=0.001) in zinc levels among patients in the manic phase (mean 111.28, SD: 33.36 µg/dL) with respect to the control group (mean 86.07, SD: 12.39 µg/dL). CONCLUSIONS: The results suggest that there could be higher levels of some toxic trace elements in the group of patients with bipolar disorder than in the healthy control group.

Blood lead and cadmium levels in a six hospital employee population. PESA study, 2009.

INTRODUCTION: Exposure to lead and cadmium is a public health problem due to the broad exposure to these toxic substances among the general population. The objective of this study is to determine blood lead and cadmium concentrations in a working population drawn from six university hospitals in Madrid, Getafe, Cartagena, Santiago de Compostela, Santander and Palma de Mallorca (Spain) and to identify associated factors. MATERIALS AND METHODS: 951 individuals participated in the study and were administered the standardized PESA® questionnaire regarding exposure to lead and cadmium. The blood lead and cadmium concentrations were measured by electrothermal atomization atomic absorption spectrometry with Zeeman background correction in Perkin-Elmer spectrometers, guaranteeing the transferability of the results. RESULTS: The median overall blood lead concentration was: 1.6 µg/dL (IQR: 0.9-2.7) and that of cadmium was: 0.21 µg/L (IQR: 0.10-0.50). There were significant differences in lead levels between men (2 µg/dL) and women (1.5 µg/dL), postmenopausal (2.6 µg/dL) and premenopausal women (1.1 µg/dL), and between participants who cooked in earthenware (2.1 µg/dL) and those who did not (1.5 µg/dL). The median of cadmium in women (0.24 µg/L) was higher than in men (0.11 µg/L) and was also higher in subjects who smoked (0.70 µg/L) than in non-smokers (0.13 µg/L). CONCLUSIONS: A reduction in blood lead and cadmium levels was observed with respect to previous studies carried out in Spain. Nevertheless, the results suggest there are certain factors which increase risk such as age, gender, menopause, age of housing, cooking in lead-glazed earthenware and exposure to cigarette smoke.

Measurement of cerium in human breast milk and blood samples.

The aim of this study was to evaluate the relationship between cerium content in human breast milk and blood plasma or serum. Blood samples and breast milk at various stages of lactation, from 5 days to 51 weeks post partum, were donated by 42 healthy breast-feeding mothers from Munich, Germany and by 26 lactating Spanish mothers from Madrid at 4 weeks post partum. Inductively coupled plasma mass spectrometry was applied for the determination of cerium in the biological samples. Cerium concentration in the digested milk samples from Munich showed low values and the arithmetic mean values ranged between the quantification limit of 5 ng/L up to 65 ng/L. The median value amounted to 13 ng/L. The cerium concentrations in the Spanish breast milk samples amounted to similar low values. The data were about a factor of eight lower than values found in a former study of samples from an eastern German province. All cerium concentrations in the German plasma samples, except for two, were at the quantification limit of 10 ng/L. Interestingly, the serum samples of the Spanish mothers showed cerium values ranging between 21.6 and 70.3 ng/L; these higher data could be explained by an enhanced intake of cerium by humans in Madrid. This could be caused by increased cerium concentrations in particulate matter due to a higher traffic volume in Madrid compared to Munich. The results obtained in this study contribute to setting reference baseline values of cerium in human breast milk and blood plasma/serum and indicate a varying cerium amount depending on the cerium environmental pollution. Possibly, the cerium content in plasma/serum could be an indicator for environmental cerium, which is not valid for breast milk.