Chromosome distribution studies in phenyl mercury acetate exposed subjects and in age-related controls.

Peripheral blood lymphocytes of phenyl mercury acetate exposed persons and a control population of the same age were cultured for 48 h. In both populations 100 metaphases were trypsin-banded and caryotyped. The relative position of the metaphase chromosomes was studied by means of centromere--centromere distances (delta2) and centromere--metaphase centre distances (d2) obtained by computer-aided mathematical transformation of the individual metaphase coordinates. By comparing both investigated cell populations we mainly observed that the chromosome combinations which statistically differ in mercury-exposed workers from the controls show an increase of centromere-centromere distances after mercury exposure. From the data we may suggest that phenyl mercury acetate influences at first the position of particular chromosomes; especially D-group chromosomes which are involved in nucleolus organisation. This may be due to a greater density of SH-wearing molecules in that region or to a possible inhibition of specific enzymes regulating the nucleolar activity. The exposure level is however too low to allow definite conclusions in this respect.