Behaviour of biological indicators of internal dose and some neuro-endocrine tests in aluminium workers.

The authors present the results of toxicological studies on aluminium from 1983 to 1988. In order to obtain reference values for serum and urine aluminium, 506 healthy adults, not occupationally exposed to the metal, residing in the Brescia area were studied. The following values were obtained: AlS = 5.8 +/- 2.9 micrograms/l; AlU 11.9 +/- 4.3 micrograms/l. The AlU and AlS values did not differ in relation to age, sex, alcohol consumption, smoking habits and residence, contrary to what has been found for some metals determined in the urine and/or blood of the same subjects. In a group of 227 subjects with occupational exposure to aluminium within the range 0.1-1.0 mg/m3, the mean levels of AlU were higher than that of the reference population; however the AlU of the workers were generally lower than 20 micrograms/l which is the upper limit for the reference population; 4 workers who were under treatment with antiacid preparations showed AlU values higher than 150 micrograms/l. Seven workers exposed to atmospheric aluminium concentrations around the TLV-TWA had higher AlU values at the end of their shift on all working days and on Friday morning the values where higher than those encountered on Monday morning. On the other hand no daily and weekly fluctuations were evident for AlS. For 14 workers the relationship between AlU and AlS values were examined in three subsequent periods after the start of working activity. Considering the same values of AlU, it was observed that the AlS increased with the duration of exposure. These results seem to indicate that AlU could be considered as indicator of current exposure and AlS as an indicator of cumulative exposure. Neuroendocrine tests were performed every 6 months in 21 workers after they had been hired. PRL and TSH values were reduced after 1 year of work and were still reduced 6 months later. Further analyses showed a different behaviour: in fact the levels of the two hormones rose above the reference values, while the HGH and other gonadotropins showed no alterations. These results seem to indicate that at the start of exposure to aluminium concentrations below TLV-TWA there is an effect on the hypothalamus-pituitary axis. This phenomenon is probably transient perhaps because of an adaptation mechanism. Further studies are however necessary to verify these results.