Genotoxic damage in zebra fish (Danio rerio) by arsenic in waters from Zimapan, Hidalgo, Mexico

The induction of micronuclei in gill cells of zebra fish (Danio rerio) maintained in calcium-magnesium bicarbonated waters from a reference well and 'Zimapan 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 As5+ (positive control); and in water from 'Zimapan 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 'Zimapan 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 'Zimapan 5' well-water 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.