Comparative toxicities of selected rare earth elements: Sea urchin embryogenesis and fertilization damage with redox and cytogenetic effects

Background: Broad-rangingadverseeffectsareknownforrareearthelements(REE),yetonlyafew studies testedthetoxicityofseveralREE,promptingstudiesfocusingonmulti-parameterREEtoxicity. Methods: TrichloridesaltsofY,La,Ce,Nd,Sm,EuandGdweretestedin Paracentrotuslividus sea urchin embryos andspermfor:(1)developmentaldefectsineitherREE-exposedlarvaeorintheoffspringof REE-exposedsperm;(2)fertilizationsuccess;(3)mitoticanomaliesinREE-exposedembryosandinthe offspring ofREE-exposedsperm,and(4)reactiveoxygenspecies(ROS)formation,andmalondialdehyde (MDA)andnitricoxide(NO)levels. Results: REEs affected P.lividus larvaewithconcentration-relatedincreaseindevelopmentaldefects, 106 to 104 M, rankingas:Gd(III)4Y(III)4La(III)4Nd(III)≅Eu(III)4Ce(III)≅Sm(III). Nominalcon- centrations ofREEsaltswereconfirmed byinductivelycoupledplasmamassspectrometry(ICP-MS). Significant increasesinMDAlevels,ROSformation,andNOlevelswerefoundinREE-exposedembryos. Sperm exposuretoREEs(105 to 104 M) resultedinconcentration-relateddecreaseinfertilization success alongwithincreaseinoffspringdamage.Decreasedmitoticactivityandincreasedaberration ratesweredetectedinREE-exposedembryosandintheoffspringofREE-exposedsperm. Conclusion: REE-associated toxicityaffectingembryogenesis,fertilization,cytogeneticandredoxend- points showeddifferentactivitiesoftestedREEs.Damagetoearlylifestages,alongwithredoxandcy- togeneticanomaliesshouldbethefocusoffutureREEtoxicitystudies.