Prevalence of iodine deficiency disorders among school children in Saudi Arabia: results of a national iodine nutrition study.

This study aimed at establishing updated data on iodine nutrition among schoolchildren in Saudi Arabia. A cross-sectional cluster survey among schoolchildren aged 8-10 years was conducted during February-April 2012. Children were clinically examined for goitre, urine and household salt samples were collected to estimate urinary iodine concenteration (UIC) and iodine content in salt. The overall goitre prevalence at the national level among 4 016 children was 4.2%. The prevalence was < 5% in all regions of the country except southern region with a prevalence of 12.7%. The median UIC of 2224 samples was 133 µg/L, with 74.3% of the surveyed children with UIC ≥ 100 µg/L. Analysis of salt samples (n = 4242) revealed that 69.8% of households were consuming adequately iodized salt. The findings suggest iodine sufficiency at the national level, however southern region still has a goitre prevalence of mild degree severity and the proportion of households consuming adequately iodized salt is still below recommendations.

Prevalence of iodine deficiency disorders among school children in Saudi Arabia: results of a national iodine nutrition study

This study aimed at establishing updated data on iodine nutrition among schoolchildren in Saudi Arabia. A cross-sectional cluster survey among schoolchildren aged 8-10 years was conducted during February-April 2012. Children were clinically examined for goitre, urine and household salt samples were collected to estimate urinary iodine concenteration [UIC] and iodine content in salt. The overall goitre prevalence at the national level among 4 016 children was 4.2%. The prevalence was < 5% in all regions of the country except southern region with a prevalence of 12.7%. The median UIC of 2224 samples was 133 microg/L, with 74.3% of the surveyed children with UIC>/=100 microg/L. Analysis of salt samples [n = 4242] revealed that 69.8% of households were consuming adequately iodized salt. The findings suggest iodine sufficiency at the national level, however southern region still has a goitre prevalence of mild degree severity and the proportion of households consuming adequately iodized salt is still below recommendations

Cette étude visait à recueillir des données mises à jour sur la nutrition en iode parmi les enfants d'âge scolaire en Arabie saoudite. Une étude transversale par sondage en grappes a été menée auprès enfants d'âge scolaire âgés de 8 à 10 ans entre février et avril 2012. Les enfants ont été soumis à un examen clinique pour le goître, et des échantillons d'urine et de sel de cuisine ont été collectés afin d'estimer la concentration d'iode urinaire et la teneur en iode dans le sel. La prévalence globale du goître au niveau national parmi les 4016 enfants était de 4,2%. La prévalence était inférieure à 5% dans l'ensemble des régions du pays, exception faite de la partie sud qui présentait une prévalence de 12,7%. La concentration médiane d'iode urinaire de 2224 échantillons était de 133 micro g/L, 74,3% des enfants examinés ayant une concentration d'iode urinaire inférieure ou égale à 100 micro g/L. Les proportions d'enfants ayant des taux de concentration d'iode urinaire inférieurs à 20, compris entre 20 et 49 et 50 et 99 micro g/L, étaient de 2,0%, 5,3% et 18,5% respectivement. L'analyse des échantillons de sel [n = 4242] a révélé que 69,8% des ménages consommaient du sel adéquatement iodé. Les résultats suggèrent un niveau de consommation en iode suffisant à l'échelle nationale, bien que la partie sud du pays continue d'avoir une prévalence du goître de sévérité moyenne, et que la proportion des ménages consommant du sel adéquatement iodé reste en deçà des recommandations

Adsorption of phenol by bentonite.

The potential of bentonite for phenol adsorption from aqueous solutions was studied. Batch kinetics and isotherm studies were carried out to evaluate the effect of contact time, initial concentration, pH, presence of solvent, and the desorption characteristics of bentonite. The adsorption of phenol increases with increasing initial phenol concentration and decreases with increasing the solution pH value. The adsorption process was significantly influenced by the solvent type in which phenol was dissolved. The affinity of phenol to bentonite in the presence of cyclohexane was greater than that in water and was lowest in the presence of methanol. Methanol was used to extract phenol from bentonite. The degree of extraction was dependent on the amount of phenol adsorbed by bentonite. X-ray diffraction analysis showed that the crystalline structure of bentonite was destroyed when cyclohexane was used. The ability of bentonite to adsorb phenol from cyclohexane decreased as the water to cyclohexane ratio was increased. Furthermore, hysteresis was observed in phenol desorption from bentonite in aqueous solutions. The equilibrium data in aqueous solutions was well represented by the Langmuir and Freundlich isotherm models. The removal of phenol from aqueous solutions was observed without surface modification.

Effect of soil/contaminant interactions on the biodegradation of naphthalene in flooded soil under denitrifying conditions.

The mineralization of 14C-labelled naphthalene was studied in pristine and oil-contaminated soil slurry (30% solids) under denitrifying conditions using a range of concentrations from below to above the aqueous phase saturation level. Results from sorption-desorption experiments indicated that naphthalene desorption was highly irreversible and decreased with an increase in the soil organic content, thus influencing the availability for microbial consumption. Under denitrifying conditions, the mineralization of naphthalene to CO2 occurred in parallel with the consumption of nitrate and an increase in pH from 7.0 to 8.6. When the initial substrate concentration was 50 ppm (i.e. close to the aqueous phase saturation level), about 90% of the total naphthalene was mineralized within 50 days, and a maximum mineralization rate of 1.3 ppm day-1 was achieved after a lag period of approx. 18 days. When added at concentrations higher than the aqueous phase saturation level (200 and 500 ppm), similar mineralization rates (1.8 ppm day-1) occurred until about 50 ppm of the naphthalene was mineralized. After that the mineralization rates decreased logarithmically to a minimum of 0.24 ppm day-1 for the rest of the 160 days of the experiments. For both of these higher concentrations, the reaction kinetics were independent of the concentration, indicating that desorption of the substrate governs the mineralization rate. Other results indicated that pre-exposure of soil to oil contamination did not improve the degradation rates nor reduce the lag periods. This study clearly shows the potential of denitrifying conditions for the biodegradation of low molecular weight PAHs.