Use of <Superscript>82</Superscript>Br and <Superscript>131</Superscript>I radionuclides in studies of goitrogenic effects of exogenous bromide

The interference of excessive bromide intake with iodine metabolism in the rat was studied using ⁸²Br and ¹³¹I radionuclides. Mainly lactating rat dams and their pups were used, in addition to adult male rats, in the present studies. Particularly, the influence of high bromide intake in lactating rat dams on the transfer of iodine and bromide to suckling young through breast milk was evaluated. The induction of hypothyroid status in the pups by high bromide intake in the mothers was proved unambiguously. Excessive bromide in lactating rat dams caused a marked decrease in plasma levels of thyroid hormones both, in the mothers and in their sucklings. The effects of an enhanced bromide intake on the thyroid function in relation to iodine status in the animals were also followed. Marked goitrogenic and thyrotoxic effects of excessive bromide in adult rats were significantly enhanced under the conditions of simultaneous iodine deficiency in the experimental animals.     

Comparison of strategies to quantify uncertainty of lead measurements in biological tissue at mg kg<Superscript>–1</Superscript> level

The expression of measurement uncertainty in analytical chemistry still presents some difficulties. According to the various guides and standards, several approaches are possible. This paper present two referenced approaches applied to the determination of Pb in a biological tissue at the mg kg^–1 level. Estimations were achieved, either from inter-laboratory precision data, or from the uncertainty propagation equation applied to the measurements of a single laboratory. When comparing final values, for an average concentration of about 2.0 mg kg^–1, expanded uncertainties range from ±0.05 mg kg^–1 up to ±0.31 mg kg^–1, i.e. by a factor of 6. Obviously, both approaches of estimating uncertainty do not cover the same sources of uncertainty and it is interesting to try to understand better these discrepancies in order to try to define realistic guidelines for analysts. Moreover the experimental results of the study are given where a wide number of techniques is applied. Received: 5 May 2002 Accepted: 17 June 2002 Correspondence to M. Feinberg