[Evaluation of the effects on the nervous system from exposure to low concentrations of mercury in employees manufacturing fluorescent lights].

In order to evaluate the effects of low inorganic mercury concentrations on workers employed in the manufacture of fluorescent lamps, a stratified sample of workers was selected at random and assigned to three groups according to the level of exposure. In all three groups, the urinary mercury values were within the normal range for unexposed population. Among the indicators of effect the simple reaction times test showed statistically significant differences between the three groups. Also "state anxiety" and "trait anxiety", investigated by the S.T.A.I. questionnaires, differed between the unexposed group and the other two. A positive correlation was found between simple reaction times and the state and trait anxiety scores in the whole sample and in the subsample of women. Moreover, the prevalence of symptoms related to low mercury exposure, collected by a questionnaire, was higher in the two exposed groups. Due to the absence of group-differences for the urinary mercury levels, interpretation of the results is cumbersome. On the one hand it cannot be ruled out that the unexposed group (mainly white collar workers) had some characteristics which could explain the difference in the simple reaction times test and in anxiety. Conversely, if a true mercury effect does indeed exist, the similarity of the performance between the second and third groups (both consisting of exposed blue collar workers) could be explained if we assume that the high turn-over inside the factory could have caused a similar previous exposure to mercury vapours.