[Urban development and the demographic situation in Chaco and its capital between 1960 and 1990]. / El desarrollo urbano y las particularidades demograficas del Chaco y su capital entre 1960 y 1990.

"The large demographic growth registered in the Chaco province [of Argentina] at the beginning of this Century slowed down since the 1950s as a result of the successive economic crisis undergone by this province. The demographic response was the outmigration toward the more developed areas of the country and to the capital city of Chaco. A large share of Resistencia demographic growth is provided by this internal migration. This rapid increase makes inadequate the functional and the service structure of the city." (SUMMARY IN ENG)

Problems concerning the usefulness of adjustment of urinary cadmium for creatinine and specific gravity.

A previous study concluded that there are some doubts as to the validity of creatinine as a parameter for adjusting the values of biological indicators determined on spot samples of urine, since it is subject to marked inter- and intraindividual variations. Furthermore, since there was only a moderate correlation between creatinine levels and specific density, it can be assumed that these two parameters cannot be used indifferently for adjustment. Nevertheless, it seemed advisable to verify whether correction of cadmium values determined from spot samples offers any practical advantages. For this purpose, 105 subjects with occupational exposure to cadmium were examined. They collected their 24-h urine and spot samples separately at 8.00 h. There was a close correlation between CdU/spot samples and CdU/24 h. The correlation index was very similar both for CdU/spot values expressed in microgram/l and for values adjusted according to creatinine or 1024 specific gravity. These results show that no particular advantages are offered by adjusting CdU according to creatinine or specific gravity.

Reliability of urinary creatinine as a parameter used to adjust values of urinary biological indicators.

The values of biological indicators used in biological monitoring are usually determined on spot samples of urine. In order to reduce the variations due to dilution, it is common practice to correct the values according to reference parameters, such as urinary creatinine concentration and specific gravity. The aim of the present study was to verify whether creatinine possesses the necessary characteristics for adjustment. The levels of creatinine were not influenced by diuresis, but, contrary to what was expected, the values of the metabolite showed marked intra- and interindividual variations. These data raise serious doubts as to the validity of creatinine as a parameter that can be used for adjustment purposes, and suggest that it would be advisable to ascertain for each biological indicator whether in fact adjustment is of any use. Lastly, since there was only a slight correlation between creatinine levels and specific gravity values, it is concluded that these two parameters cannot be used indifferently for adjustment.

Cadmium concentrations in blood and urine of pregnant women at delivery and their offspring.

The levels of cadmium in blood (CdB) and in urine (CdU) were measured in 40 women at delivery and in their offspring. The women were not occupationally exposed to cadmium. The CdB levels in the pregnant women were significantly lower than in a control group consisting of 40 subjects of the same sex and age living in the same area. The difference can probably be ascribed to the physiological hemodilution that takes place in pregnancy. The CdU levels in the two groups were identical, which suggests that no mobilization of the metal from tissue deposits occurs during pregnancy. The presence of cadmium in the blood and urine of the newborn demonstrates that cadmium crosses the placental barrier. There was a rather high correlation between the CdU levels of mothers and offspring. Since only traces of cadmium are present in tissues at birth, it is speculated that the CdU levels in the newborn are influenced by the tissue deposits of cadmium in the mother. Further research is required to ascertain whether, in the case of women occupationally exposed to cadmium or living in cadmium polluted areas, transfer of the metal across the placenta can produce toxic effects in the foetus.