Assessment of the natural radioactivity in the Brazilian state of Rio Grande do Norte.

Fifty-one soil samples were collected to a depth of 30 cm in the central and eastern region of the Brazilian state of Rio Grande do Norte. Concentrations of background radionuclides in soil samples were determined by gamma ray spectrometry with an HPGe detector. The average concentrations of 226Ra, 232Th, and 40K in the surveyed soils were 29.0 +/- 19.4 Bq kg-1, 46.6 +/- 36.2 Bq kg-1, and 677.8 +/- 434.9 Bq kg-1, respectively. The bedrock of Santana do Matos (Rio Grande do Norte) showed fairly high radioactivity (90 Bq kg-1 of 226Ra, 285.6 Bq kg-1 of 232Th, and 1,414 Bq kg-1 of 40K). Radiological measurements carried out in Santana do Matos with a hand-held scintillometer revealed external gamma radiation ranging from 200-330 nGy h-1 in the down-town area. Higher values were recorded in the surroundings of that town.

Radon concentrations inside castles and other ancient buildings.

Sixty-two measurements of Rn-222 concentrations were made in 24 castles and 13 ancient buildings in 30 different places situated in the provinces of Parma and Reggio Emilia (Northern Italy). The method used was that of activated carbon canisters which were placed in selected settings for at least 48 h in the period starting from December 1990 to May 1991. It was possible to determine the amount of radon in each canister via its daughters gamma emitters counted by NaI(T1) and Ge(I) detectors. The mean radon concentrations were 72 Bq m-3 (arithmetic mean) and 49 Bq m-3 (geometric mean), a good deal higher than the values obtained from measurements carried out in modern dwellings in the same area; 30 Bq m-3 (arithmetic mean) and 19 Bq m-3 (geometric mean).

Goiter size and thyroid function in an endemic goiter area in northern Italy.

Thyroid function was studied in a large number of subjects residing in Varsi, a town in the province of Parma, Italy. In this area, endemic goiter associated with moderate iodine deficiency [59 +/- 3 (+/- SE) microgram iodine/g creatinine], as defined by WHO criteria, affects 65% of the population. Serum T4, T3, thyroglobulin (Tg), and TSH concentrations were measured by RIA in 1218 subjects. The TSH response to TRH was determined in 108 subjects selected randomly from the groups with different grades of goiter. No significant change in serum T4 concentrations was found in subjects with different grades of goiter. Serum T3 concentrations were higher in subjects with the larger goiters. Serum Tg concentration progressively increased, and serum TSH progressively decreased with increasing goiter size. The TSH response to TRH was diminished in subjects with larger goiters. The findings of decreasing serum TSH concentrations and blunted TSH responses to TRH as goiter size increased suggest the possibility of autonomous thyroid function in the larger goiters in subjects residing in this area of moderate iodine deficiency.