Boron removal by the duckweed Lemna gibba: a potential method for the remediation of boron-polluted waters.

Boron (B) is often found in polluted and desalinated waters. Despite its potentially environmental damaging effects, efficient treatments are lacking. The duckweed Lemna gibba has been shown to remove toxic elements from water; however, its applicability to B removal is unknown. In this study, L. gibba was examined for its tolerance to B in water and its B removal efficiency. Duckweed plants were grown in outdoor 12-day batch experiments in nutrient solution containing 0.3-10 mg B L(-1). Plant biomass production was not affected by B over the tested concentrations during the 12-day cultivation period. Boron removal and the bioconcentration factor of B in L. gibba were highest at initial B concentrations below 2 mg L(-1), and decreased as the initial B concentration increased. Boron content in the plants at the end of the experiment ranged between 930 and 1900 mg kg(-1) dry weight, and was comparable to that of wetland plants reported to be good B accumulators. Boron removal by L. gibba may therefore be a suitable option for the treatment of water containing B concentrations below 2 mg L(-1).

[Prevalence of iron-deficiency anemia in schoolchildren and adolescents, Medellín, Colombia, 1999]. / Prevalencia de anemia ferropénica en escolares y adolescentes, Medellín, Colombia, 1999.

OBJECTIVE: This research had two objectives: (1) to determine the prevalence of iron-deficiency anemia and describe iron consumption in the diet of schoolchildren and adolescents enrolled in public and private schools of the urban area of the city of Medellín, Colombia, in the 1999-2000 school year and (2) to explore the associations that age group, sex, socioeconomic class, and intestinal parasitism show with iron-deficiency anemia and iron deficiency. METHODS: A cross-sectional study was carried out among 960 students from 6 to 18 years old who were selected by simple random sampling after stratified multistage sampling and clustering in public and private schools in districts of Medellín. Body iron content was evaluated by determining ferritin and hemoglobin levels, average corpuscular volume, and amplitude of the erythrocyte distribution; the presence of intestinal parasites was evaluated through stool analysis; nutritional status was evaluated by means of anthropometric measurements; and consumption of iron and vitamin C was evaluated using a semiquantitative questionnaire on food intake. In order to define the cases of iron-deficiency anemia and of iron deficiency we used the standard definitions of the World Health Organization, based on ferritin and hemoglobin values. We used nonparametric tests, with a significance level of 0.05, to examine the associations between age group, sex, socioeconomic class, and the presence of intestinal parasites on the one hand and the presence of anemia on the other hand. RESULTS: The prevalence of iron deficiency was 4.9%, and the prevalence of iron-deficiency anemia was 0.6%. The prevalence of both was higher among adolescent women (P < 0.05) than in the rest of the sample studied. No significant association was found between the presence of intestinal parasites and the presence of anemia. The average daily consumption of iron (+/- standard deviation) was 5.5 mg (+/- 2.3 mg) (32% +/- 15% of the recommended dietary intake for the studied age group); the average contribution of serum iron in the diet was 0.7 mg (+/- 0.7 mg). Comparing the children who did and who did not have anemia, there were no significant differences in iron consumption and the type of iron consumed. The anthropometric parameter that showed the greatest association with the presence of anemia was height for age. CONCLUSIONS: The prevalences of iron deficiency and of iron-deficiency anemia found in the population studied were low, according to the parameters for hemoglobin and ferritin as defined by the World Health Organization as being normal for these population groups. The low prevalence of blood-sucking parasites, adequate consumption of vitamin C, and the refined mechanisms with which the body regulates iron homeostasis may have contributed to these results. Adequate iron content in the diet of adolescents should be maintained, and education campaigns should be implemented to help prevent iron deficiency in this population group.

Prevalencia de anemia ferropénica en escolares y adolescentes, Medellín, Colombia, 1999 / Prevalence of iron-deficiency anemia in schoolchildren and adolescents, Medellín, Colombia, 1999

OBJETIVO: Determinar la prevalencia de anemia ferropénica y describir el consumo de hierro en la dieta de escolares y adolescentes matriculados en colegios oficiales y privados de la zona urbana de la ciudad de Medellín, Colombia, en el año escolar 1999­2000, así como explorar la asociación entre grupo de edad, sexo, clase socioeconómica y parasitismo intestinal por un lado, y anémica ferropénica y deficiencia de hierro por el otro. MÉTODOS: Se realizó un estudio de corte transversal en 960 estudiantes de 6 a 18 años de edad que fueron elegidos por muestreo aleatorio simple tras un muestreo polietápico estratificado y por conglomerados de colegios oficiales y privados en comunas de la zona de Medellín. Se evaluaron el contenido corporal de hierro mediante determinaciones de ferritina, hemoglobina, volumen corpuscular medio y amplitud de la distribución eritrocitaria; la presencia de parásitos intestinales mediante análisis coprológico; el estado nutricional por medio de mediciones antropométricas; y el consumo de hierro y vitamina C mediante un cuestionario semicuantitativo de ingesta alimentaria. Para definir los casos de anemia ferropénica y de deficiencia de hierro se usaron las definiciones estándar de la Organización Mundial de la Salud basadas en los valores de ferritina y hemoglobina. También se examinó la asociación entre grupo de edad, sexo, clase socioeconómica y presencia de parásitos intestinales por un lado y la presencia de anemia por el otro mediante pruebas no paramétricas con un nivel de significación de 0,05. RESULTADOS: La prevalencia de deficiencia de hierro fue de 4,9 por ciento y la de anemia ferropénica, de 0,6 por ciento. Se encontró una mayor prevalencia de ambas en mujeres adolescentes (P < 0,05) que en el resto de la muestra estudiada. No se demostró ninguna asociación significativa entre la presencia de parásitos intestinales y la de anemia. El consumo promedio de hierro diario fue de 5,5 ±2,3 mg (desviación estándar [DE]) (32 por ciento ±15 por ciento [DE] de la ingesta dietética recomendada [RDA] para el grupo de edad estudiado); el aporte promedio de hierro hemático en la dieta fue de 0,7 ±0,7 mg [DE]. No se encontraron diferencias significativas en la cantidad y el tipo de hierro consumido entre los niños con y sin anemia. El parámetro antropométrico que mostró la mayor asociación con la presencia de anemia fue la relación entra la estatura y la edad...