Once they are found as pollutants in some biota, they may besubjected to interactions with organisms, originating phenomena∗Corresponding author. Tel.: +55 1438800578.E-mail address: castrogr@ibb.unesp.br (G.R. Castro).like bioaccumulation and conversion to organometallic species,as examples. Bioaccumulation implies that, as the time goes by,some animals that live in polluted environments will retain in theirtissues an increasing amount of such a pollutants. On the otherhand, organometallic species are generated by bacterial activity,which forms substances composed by metals covalently bonded toorganic carbon chains. Organometallic substances, when excretedin the medium, are generally more harmful than the free metalcations themselves, because they end up acquiring higher affin-ity with the fat tissues of animals’ bodies increasing greatly theirbioconcentration factors