[Evoked potentials and psychometric tests in the diagnosis of subclinical neurological damage in a group of workers exposed to low concentrations of mercury vapor]. / Potenciales evocados y test psicométricos en el diagnóstico de daño neurológico subclínico de un grupo de trabajadores expuestos a bajas concentraciones de vapores de mercurio.

We study the effects of low concentrations of mercury vapour on the nervous system of a group of eleven workers of a chloroalkali plant exposed to it. Twenty-three non-exposed workers in the same factory were used as control group. We used clinical and analytic explorations, psychometric tests and evoked potentials to evaluate the subjects. The average Hg in urine of the exposed group was 41.74 micrograms/gr creatinine and the average of the non-exposed group as 9.71 mu/yr. In the exposed group the evoked potentials have found a slowing-down of conduction in all the nervous paths studied (optical, auditive and somatosensory) and in the latency of P300 wave, although this was not statistically significant compared to the control group. Of the psychometric test used, only Rey's Complex Figure Test showed deterioration in the visual memory subtest of the exposed group (p < 0.05) compared to the control group, although in Wechsler's digit span test lower scores were obtained which were close to being statistically significant comparing the averages of the two groups (0.05 < p < 0.051). Bearing in mind these results we think that the amounts of Hg in urine and TLV-TWA (50 micrograms/gr creatinine and 50 micrograms/m3 respectively) accepted by most authors as innocuous should be reduced.

Electroretinographic changes during childhood and adolescence.

Electroretinogram (ERG) changes with age have been studied widely, but there is no general agreement about the age at which ERG parameters reach adult values. We studied 296 eyes from 148 healthy subjects, divided into 14 age groups, ranging from 1 week to 21 years. Although most of the maturational changes or ERG take place during the first six months, the a wave completes development at three years of age and the b component shows a smooth increase in latency between 3 and 18-21 years. The latter component also shows an increase in amplitude from 7-8 to 12-14 years. During the first period of maturation the b wave parameters follow a multiplicative model. These data are discussed in relation to previously reported findings on ERG maturation and to morphological and functional eye changes with age.