Environmental Engineering Reference
In-Depth Information
Dimethyl. phthalate. (DMP),. one. of. the. PAEs. produced. on. a. large. scale,.
was. not. found. to. induce. carcinogenic. activities. in. both. male. and. female.
rats.(National.Toxicology.Program.1995)..However,.a.DMP.uptake.in.higher.
amounts.triggered.central.nervous.depression.and.noticeable.kidney.dam-
age.(Autian.1973)..Other.bioassays.using.scud.(
H. azteca
),.midge.(
Chironomus
tentans
),. and. California. blackworm. (
Lumbriculus variegates
). showed. that.
H. azteca
. was. most. sensitive. to. DMP. with. the. mechanism. of. narcosis.
response.(Call.et.al..2001b)..At.50.mg/L.of.DMP,.mortality.at.the.rate.of.95%.
was.observed.in.
H. azteca
.
DMTP,. a. monomer. in. the. polymer. industry,. was. tested. for. its. toxicity. as.
early.as.1973.(Krasavage.et.al..1973)..The.initial.tests.supported.that.DMTP.was.
basically.a.nontoxic.compound.ingested.at.low.levels.by.organisms..Although.
a.reduced.body.weight.was.observed.in.the.assay,.a.syndrome-like.hematol-
ogy.was.insigniicant..The.nongenotoxicity.of.DMTP.was.demonstrated.by.
in vitro
. tests:. the. Ames. test,. DNA. single-strand. break. assays. in. CO60. cells.
and.in.primary.rat.hepatocytes,.and.so.on.(Monarca.et.al..1991)..In.1995,.the.
European. Commission. initiated. an. investigation. on. the. DMTP. recovered.
from.pet.bottles.(The.Scientiic.Committee.for.Food.1995)..The.report.claimed.
that.there.was.no.special.evidence.of.harmful.effects.on.humans.when.using.
DMTP.as.the.monomer.in.pet.bottle.manufacturing.
Degradation of PAEs
PAEs. are. very. persistent. in. the. environment.. In. the. case. of. DMP,. its.
half-life.could.be.3.2.years.in.the.aquatic.environment.(Staples.et.al..1997)..
For.the.purpose.of.eliminating.such.esters,.acceleration.of.the.hydrolysis.
of.ester.bond.is.very.important.for.their.remediation..There.are.many.ways.
to.perform.the.degradation.test,.and.they.can.be.classiied.into.two.main.
categories:.abiotic.and.biotic.methods.
Abiotic Degradation
Abiotic. degradation. of. PAEs. refers. to. physicochemical. processes. such. as.
light. exposure,. artiicial. irradiation,. and. chemical. reaction,. which. occur.
without.the.participation.of.any.organism..Photolysis.is.a.very.important.but.
slower.process.for.decomposition.of.organic.chemicals.in.the.environment..
For.PAEs,.the.ester.bonds.can.be.broken.when.they.absorb.enough.ultraviolet.
radiation.(UV).at.the.range.of.290-400.nm..The.ester.bonds.rupture.by.direct.
absorption. of. the. energy. of. UV. light,. or. by. their. reaction. to. UV-activated.
matters,.such.as.oxygen.radical.and.hydroxy.radical..For.instance,.1.mg/L.of.
butyl.benzyl.phthalate.(BBP).was.decomposed.over.95%.after.a.direct.expo-
sure. to. sunlight. for. 28. days. (Gledhill. et. al.. 1980).. DMP. and. DEP. after. UV.
irradiation.were.decomposed.to.several.fractions.of.compounds.and.radicals.
through. breakage. of. ester. bonds. and. decarboxylation. (Balabanovich. and.
Schnabel.1998).
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