The comet assay with blood, liver and gill cells, and the occurrence
of micronuclei (MN) other nuclear abnormalities (ENA) in
erythrocytes were used to assess the genotoxic potential of lead
in vivo. Metallothionein content was measured in fish liver in order
to evaluate the protection of fish against lead toxicity. In another set
of experiments fish erythrocytes were exposed to lead in vitro and
the following endpoints were analyzed: number of viable cells, DNA
integrity using the comet assay, and lysosomal membrane stability,
measured by the neutral red retention assay (NRRA), to identify
cellular stress. Lysosomal membrane stability is considered one of
the most reliable of the recommended biomarkers for water quality
assessment (UNEP, 1997).