Quality control assurance of strontium-90 in foodstuffs by LSC.

A method based on the separation of Sr-90 by extraction chromatography and beta determination by Liquid Scintillation Counting (LSC) technique was used for strontium analysis in food samples. The methodology consisted in prior sample treatment (drying and incineration) followed by radiochemical separation of Sr-90 by extraction chromatography, using the Sr-resin. The chemical yield was determined by gravimetric method, adding stable strontium to the matrix. Beta activity (Sr-90/Y-90) was determined using a low background liquid scintillation spectrometer (Tri-Carb 3170 TR/SL, Packard). The accuracy and the precision of the method, was performed previously through recovery trials with Sr-90 spiked samples, using the same type of matrices (milk, complete meals, meat and vegetables). A reference material (IAEA_321) was now used to measure the accuracy of the procedure. Participation in interlaboratory comparison exercises was also performed in order to establish an external control on the measurements and to ensure the adequacy of the method.

Characterisation of the somatic evolution of Portuguese children with Trisomy 21--preliminary results.

We present preliminary results of a cross-sectional study which had the following objectives: 1--to develop percentile curves of weight, height and head circumference of Portuguese children with Trisomy 21 from 0 to 48 months of age; 2--a comparison of the growth of children with Trisomy 21 with a control population of their siblings, and 3--a comparison between the growth of Portuguese and American children with Trisomy 21 (based on the data of Cronk et al). We conclude that: 1--there is growth delay (weight, height, head circumference) in the Portuguese children with Trisomy 21, in all of the parameters evaluated and in all age groups; 2--Portuguese children with Trisomy 21 present values similar to those obtained by Cronk et al until 24 months of age; 3--from the age of 30 months onward Portuguese children with Trisomy 21 were heavier and taller than American children with Trisomy 21. This supports the usefulness of percentile curves specifically for Portuguese children with Trisomy 21.