Environmental Engineering Reference
In-Depth Information
FIgure 23.5
Worker.performing.task.above.shoulder.level.
hAzArdous chemIcAls
Hazardous. and. toxic. substances. can. be. deined. as. those. chemicals. present. in.
the. workplace. that. are. capable. of. causing. harm. (see. Figure 23.6).. In. this. deini-
tion,. the. term. “chemicals”. includes. dusts,. mixtures,. and. common. materials. such.
as.paints,.fuels,.and.solvents..OSHA.currently.regulates.exposure.to.approximately.
400. substances.. The. OSHA. Chemical. Sampling. Information. ile. contains. a. list-
ing.for.approximately.1,500.substances..The.EPA's.Toxic.Substance.Chemical.Act:.
Chemical.Substances.Inventory.lists.information.on.more.than.62,000.chemicals.or.
chemical.substances..Some.libraries.maintain.iles.of.Material.Safety.Data.Sheets.
(MSDSs).for.more.than.100,000.substances..It.is.not.possible.at.this.time.to.address.
or.regulate.the.hazards.associated.with.each.of.these.chemicals.that.can.potentially.
be.found.in.the.workplace.
Because.there.is.no.evaluation.instrument.that.can.identify.the.chemical.or.the.
amount. of. chemical. contaminant. present,. it. is. not. possible. to. make. a. real-time.
assessment.of.a.worker's.exposure.to.potentially.hazardous.chemicals..If.this.is.not.
enough.of.a.problem,.the.Threshold.Limit.Values.(TLVs).provided.by.the.American.
Conference. of. Governmental. Industrial. Hygienist. (ACGIH). in. 1968. is. the. basis.
of. OSHA's. Permissible. Exposure. Limits. (PELs).. In. the. early. 2000s,. workers. are.
being. provided. protection. with. chemical. exposure. standards. that. are. more. than.
40.years.old..The.ACGIH.regularly.updates.and.changes.its.TLVs.based.upon.new.
