Environmental Engineering Reference
In-Depth Information
no.relective.surfaces.(such.as.mirrors.or.highly.polished.furniture).as.even.a.relected.
laser.beam.can.be.hazardous..Suitable.shielding.to.contain.the.laser.beam.should.be.
provided..OSHA.covers.protection.against.laser.hazards.in.its.construction.regulations.
The.eye.is.the.organ.most.vulnerable.to.injury.induced.by.laser.energy..The.rea-
son.for.this.is.the.ability.of.the.cornea.and.lens.to.focus.the.collimated.laser.beam.
on.a.small.spot.on.the.retina..The.fact.that.infrared.radiation.of.certain.lasers.may.
not.be.visible.to.the.naked.eye.contributes.to.the.potential.hazard..Lasers.generating.
in.the.ultraviolet.range.of.the.electromagnetic.spectrum.can.produce.corneal.burns.
rather.than.retinal.damage.because.of.the.way.the.eye.handles.ultraviolet.light..Other.
factors.that.have.a.bearing.on.the.degree.of.eye.injury.induced.by.laser.light.are
.
1.. Pupil. size. (the. smaller. the. pupil. diameter,. the. less. the. amount. of. laser.
energy.permitted.to.the.retina)
.
2.. Ability.of.the.cornea.and.lens.to.focus.the.incident.light.on.the.retina
.
3.. Distance.from.the.source.of.energy.to.the.retina
.
4.. Energy.and.wavelength.of.the.laser
.
5.. Pigmentation.of.the.eye.of.the.subject
.
6.. Place.of.the.retina.where.the.light.is.focused
.
7.. Divergence.of.the.laser.light
.
8.. Presence.of.scattering.media.in.the.light.path
leAd
Overexposure.to.lead.is.one.of.the.most.common.overexposures.found.in.industry..
It.is.also.a.major.potential.public.health.risk..Lead.poisoning.is.the.leading.environ-
mentally.induced.illness.in.children..At.greatest.risk.are.children.under.the.age.of.
six. because. they. are. undergoing. rapid. neurological. and. physical. development.. In.
general.populations,.lead.may.be.present.at.hazardous.concentrations.in.food,.water,.
and.air..Sources.include.paint,.urban.dust,.and.folk.remedies.
Lead. is. commonly. added. to. industrial. paints. because. of. its. characteristic. of.
resisting. corrosion.. Industries. with. particularly. high. potential. exposures. include.
construction.work.involving.welding,.cutting,.brazing,.abrasive.surface.blasting,.etc.,.
on.lead.painted.surfaces;.most.smelter.operations.either.as.a.trace.contaminant.or.
as.a.major.product;.secondary.lead.smelters,.where.lead.is.recovered.from.batteries;.
radiator.repair.shops;.and.iring.ranges..Oral.ingestion.may.represent.a.major.route.
of.exposure.in.contaminated.workplaces..Lead.soldering.usually.does.not.represent.
an.inhalation.risk.because.controlling.the.temperature.of.lead.below.900°F.(melting.
temperature.=.621°F).is.effective.in.controlling.lead.fuming..Most.exposures.occur.
with.inorganic.lead..Organic.(tetraethyl.and.tetramethyl).lead,.which.was.added.to.
gasoline.up.until.the.late.1970s,.is.not.commonly.encountered..Organic.forms.may.
be.absorbed.through.the.skin,.while.inorganic.forms.cannot..Inorganic.lead.is.not.
metabolized,. but. is. directly. absorbed,. distributed,. and. excreted.. The. rate. depends.
on. its. chemical. and. physical. form. and. on. the. physiological. characteristics. of. the.
exposed.person.(e.g.,.nutritional.status.and.age)..Once.in.the.blood,.lead.is.distributed.
primarily. among. the. person's. blood,. soft. tissue. (kidney,. bone. marrow,. liver,. and.
brain),.and.mineralizing.tissue.(bones.and.teeth)..Absorption.via.the.gastrointestinal.
