The induction of micronuclei in gill cells of zebra fish
(Danio rerio) maintained in calcium–magnesium bicarbonated
waters from a reference well and ‘Zimapa´n 5’ well, the
latter with an arsenic (As) content ranging from 0.395 to
0.630 p.p.m., was studied. The specimens were studied during
180 days in three separated lots: in reference well-water
(negative control), in reference water to which was added
5 mg/l As51 (positive control); and in water from ‘Zimapa´n
5’ well, with 65 specimens/lot. In waters an As concentration
diminution was observed with time, whereas in fish
there was an increase. After 30 days there was an As diminution
in water from positive control of 1092.65 p.p.b.
(36.42 p.p.b./day), whereas in fish it had increased to
523.81 p.p.b. (17.46 p.p.b./day). For the water from
‘Zimapa´n 5’ well, there was a diminution of 211.40 p.p.b.
(7.04 p.p.b./day), and in fish there was an increase of
74.73 p.p.b. (2.49 p.p.b./day). In relation to micronucleus
frequency in gill cells, at the end of 180 days in the negative
control there was a spontaneous generation of 0.8 micronuclei/
1000 cells, in the positive control there was a micronucleus
frequency 163.5 times greater than in the negative
control, whereas for the fish exposed to ‘Zimapa´n 5’ wellwater
the micronucleus frequency was 56.25 times greater
than in the negative control. Taken together these results
demonstrate the genotoxicity to Danio rerio of As in the well
water.