Environmental Engineering Reference
In-Depth Information
and.copper..It.has.a.wide.range.of.industrial.usages,.including.batteries,.pig-
ments,. metal. coatings,. and. plastics.. Cadmium. enters. into. the. atmosphere.
from.mining.and.other.industrial.activities.such.as.burning.coal.and.from.
household.wastes..All.biota,.including.plants,.animals,.and.human.beings,.
take.up.cadmium.from.the.environment..Cadmium.can.stay.in.the.human.
body.for.a.very.long.time.and.can.build.up.from.many.years.of.exposure.to.
low.levels.(ATSDR.1999).
Arsenic. is. widely. distributed. in. the. earth's. crust. and. may. enter. the. air,.
water,.and.land.from.wind-blown.dust.and.reach.the.aquatic.systems.from.
runoff.and.leaching..It.combines.with.oxygen,.chlorine,.and.sulfur.to.form.
inorganic.arsenic.compounds.in.the.environment..In.animals.and.plants,.it.
combines. with. carbon. and. hydrogen. to. form. organic. arsenic. compounds..
Fish. and. shellish. can. accumulate. arsenic.. Fortunately,. most. of. this. arse-
nic.is.in.an.organic.form.called.arsenobetaine,.which.is.much.less.harmful..
Inorganic.arsenic.compounds.are.mainly.used.to.preserve.wood;.for.exam-
ple,. copper-chromated. arsenic. (CCA). has. been. used. in. “pressure-treated”.
lumber..Although.CCA.is.no.longer.allowed.for.residential.uses.in.the.United.
States,.it.is.still.used.in.industrial.applications..Organic.arsenic.compounds.
are.used.as.pesticides,.mainly.on.cotton.plants..There.is.some.evidence.sug-
gesting. that.long-term. exposure. to.arsenic. in.children. may.result. in.lower.
IQ.scores..Arsenic.can.cross.the.placenta.and.has.been.found.in.fetal.tissues..
Arsenic.is.also.found.at.low.levels.in.breast.milk.(ATSDR.2005).
Oxidative Stress
Oxidative.stress.(OS).is.a.general.term.used.to.describe.the.steady-state.level.
of.oxidative.damage.to.a.cell,.tissue,.or.organ.caused.by.the.reactive.oxygen.
species.(ROS)..This.damage.can.affect.a.speciic.molecule.or.the.entire.organ-
ism..ROS,.such.as.free.radicals.and.peroxides,.represent.a.class.of.molecules.
that.are.derived.from.the.metabolism.of.oxygen.and.exist.inherently.in.all.
aerobic.organisms.(Granot.and.Kohen.2004)..Most.ROS.are.derived.from.the.
endogenous.sources.as.by-products.of.normal.and.essential.metabolic.reac-
tions,. such. as. energy. generation. from. mitochondria. or. detoxiication. reac-
tions.involving.liver.cytochrome.P-450.enzyme.system..Exogenous.sources.
include. environmental. pollutants. such. as. emission. from. automobiles. and.
industries,. exposure. to. cigarette. smoke,. consumption. of. excess. alcohol,.
asbestos,.exposure.to.ionizing.radiation,.and.bacterial,.fungal,.or.viral.infec-
tions.(Stohs.and.Bagchi.1995).
Autism
Autism.is.a.complex.developmental.disability.that.typically.appears.during.
the. irst. 3. years. of. life,. resulting. from. a. neurological. disorder.. This. subse-
quently. affects. not. only. the. normal. functioning. of. the. brain. but. also. the.
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