ABSTRACT
Over.the.past.two.decades,.the.number.of.livestock.and.poultry.farms.in.the.United. States.has.decreased.by.approximately.half,.while.the.number.of.animal.units.being. raised.has.increased.by.about.10%.1.This.shift.toward.fewer.but.increasingly.larger. industrialized.farms,.termed.“confined”.or.“concentrated.animal.feeding.operations”. (CAFOs),.has.resulted.in.concomitant.increases.in.pharmaceutical.use.and.manure. generated.per.unit.land.area..During.their.lifespan,.roughly.60.to.80%.of.commercial. livestock.are.treated.with.antibiotics.as.therapeutic,.prophylactic,.or.growth.promoting.agents,2.and.much.of.the.ingested.dose.is.excreted.unchanged.or.as.active.metabolites.3.Hormones.are.also.used.for.growth.promotion.and.reproductive.control..In. addition,.hormones.and.their.metabolites.are.produced.and.excreted.naturally,.with. more.than.50.tons.of.reproductive.hormones.being.released.annually.by.farm.animals.in.the.United.States.4.As.a.result,.the.130.billion.pounds.of.manure.produced. every.year.represent.an.expansive.source.of.pharmaceutical.contamination.
