General PopulationsThe general population may be exposedto arsenic in air, drinking water, and food.Of these, food is usually the largestsource of arsenic.Some areas of the United States containunusually high naturallevels of arsenic inrock; this can lead to unusually highlevels of arsenic in soil or water.Prior to 2003, arsenic was used in theproduction of woodpreservatives,primarily copper chromated arsenate(CCA); arsenical woodpreservatives havebeen phased out for certain woodproducts. Sawing or sanding woodtreated with arsenical preservatives cangenerate arsenic contaminated sawdust.Similarly, burning arsenic-treated woodcan result in elevatedarsenic levels insmoke.Various organic arsenicals are used asherbicides and as antimicrobial additivesfor animal and poultry feed.Occupational PopulationsSome occupations inwhich exposure toarsenic may occur include copper or leadsmelting and wood treatment.Workers involved in the production orapplication of pesticides containingorganic arsenicals may also be exposed tohigher levels.ToxicokineticsBoth arsenate and arsenite are wellabsorbed by both the oral and inhalationroutes. Absorption by the dermal routehas not been well characterized, but islow compared to other routes.Once absorbed, arsenates are partiallyreduced to arsenites, yielding a mixture ofAs(III) and As(V) in the blood.As(III) undergoes methylation primarilyin the liver to form monomethylarsonicacid (MMA) and dimethylarsinic acid(DMA). The rate and relative proportionof methylation production varies amongspecies.Most inorganic arsenic is promptlyexcreted in the urine as a mixture ofAs(III), As(V), MMA, and DMA.Smaller amounts are excreted in feces.In most species, including humans,ingested organic arsenical compoundssuch as MMA and DMA, undergo limitedmetabolism, do not readily enter the cell,and are primarily excreted unchanged inthe urine.Normal Human LevelsLevels of arsenic in unexposed individuals:< 1μg/L in blood<100μg/L in urine≤1 ppm in nails≤1 ppm in hairBiomarkersMeasurement of urinary arsenic levels isgenerally accepted asthe most reliableindicator of recentarsenic exposure.Environmental LevelsAir1-3 ng/m3in remote locations.20-100 ng/m3in urban areas.Sediment and SoilMean and range of arsenic in soil andother surficial materials in the U.S. are7.2 and <0.1–97μg/g, respectively.WaterDrinking water generally contains anaverage of 2μg/L of arsenic, althoughhigher levels havebeen measured insome parts of the U.S.Arsenic levels ranging from 0.138 to1,700μg/L have been measured insurface water in the U.S.ReferenceAgency for Toxic Substances and DiseaseRegistry (ATSDR). 2007. ToxicologicalProfile for Arsenic. Atlanta, GA: U.S.Department of Health and HumanServices, Public Health Services.ToxGuideTMforArsenicAsCAS# 7440-38-2October 2007U.S. Department of Health andHuman ServicesPublic Health ServiceAgency for Toxic Substancesand Disease Registrywww.atsdr.cdc.govContact Information:Division of Toxicologyand Environmental MedicineApplied Toxicology Branch1600 Clifton Road NE, F-32Atlanta, GA 303331-800-CDC-INFO1-800-232-4636www.atsdr.cdc.gov/toxpro2.htmlToxicokinetics andNormal Human LevelsBiomarkers/EnvironmentalLevelsSources of ExposureThe ToxGuideTMis developed to be used as a pocket guide. Tear off at perforation and fold along lines.The ToxGuideTMis developed to be used as a pocket guide. Tear off at perforation and fold along lines.Chemical and PhysicalInformationRoutes of ExposureRelevance to Public Health (Health Effects)Health effects are determinedby the dose (how much), theduration (how long), and theroute of exposure.Inhalation – Minor route of exposure forthe general population. Predominantroute for occupational exposure.Oral – Predominant route of exposurefor the general population; for mostindividuals diet is the largest source ofarsenic exposure. Ingestion of arsenic indirt through hand-to-mouth activity maybe an important route of exposure foryoung children.Dermal – Minor route of exposure.Arsenic in the EnvironmentArsenic cannot be destroyed in theenvironment. It can only change its formor become attached toor separated fromparticles.Arsenic attached to very small particlesmay stay in the air for many days andtravel long distances.Arsenic in soil may be transported bywind or in runoff or may leach into thesubsurface soil.Arsenic is largelyimmobile in agricultural soils, therefore, ittends to concentrate and remain in uppersoil layers indefinitely.Transport and partitioning of arsenic inwater depends upon the chemical form.Soluble forms move with the water andmay be carried long distances. Arsenicmay be adsorbed from water ontosediments or soils.Arsenic is a metalloidArsenic is ordinarily a steel gray metallike material that occurs naturally.Arsenic compounds can be categorizedas inorganic or organic.Inorganic arsenic is primarily used as apreservative for woodto make it resistantto rotting and decay. In 2003, the use ofarsenic-containing wood preservativeswas phased out for certain residentialuses such as play structures, picnic tables,decks, fencing, andboardwalks. Arsenicwood preservatives are still used inindustrial applications.Inorganic arsenic occurs naturally in soiland in many kinds of rock, especially inminerals and ores that contain copper orlead.Elemental arsenic is used as an alloyingelement in ammunition and solders, as ananti-friction additive to metals used forbearings, and to strengthen lead-acidstorage battery grids.In the past, inorganic arsenic compoundswere used as pesticides; this use is nolonger permitted.MMA is used for weed control on cotton,turf grass and lawns and under trees,vines, and shrubs. DMA, also referred toas cacodylic acid, isused for weed controlunder nonbearing citrus trees, aroundbuildings and sidewalks, and for lawnrenovation.Health EffectsInhalation of inorganic arsenic may causerespiratory irritation, nausea, skin effects,and increased risk of lung cancer.Acute high dose oral exposure toinorganic arsenic may cause nausea,vomiting, diarrhea, cardiovascular effectsand encephalopathy.Long term oral exposure to low levels ofinorganic arsenic may cause dermaleffects (such as hyperpigmentation andhyperkeratosis, corns and warts) andperipheral neuropathy characterized by anumbness in the hands and feet that mayprogress to a painful “pins and needles”sensation. There may also be anincreased risk of skin cancer, bladdercancer, and lung cancer.Oral exposure to MMA may result ingastrointestinal damage. Kidney effectsmay be observed following chronicexposure.Chronic oral exposure to DMA mayresult in urinary bladder and kidneyeffects.Children’s HealthChildren who are exposedto high levelsof arsenic exhibit symptoms similar tothose seen in adults, includingcardiovascular, dermal, and neurologicaleffects, and vomiting following ingestion.There is some evidence that metabolismof inorganic arsenic in children is lessefficient than in adults.Minimal Risk Levels (MRLs)InhalationNo acute-, intermediate- or chronicduration inhalation MRLs were derivedfor inorganic arsenic or organic arseniccompounds.OralAn MRL of 0.005 mg As/kg/day hasbeen derived for acute-duration oralexposure (≤14 days) to inorganic arsenic.No intermediate-duration oral MRL wasderived for inorganic arsenic.An MRL of 0.0003 mg As/kg/day hasbeen derived for chronic-duration oralexposure (≥1 year) to inorganic arsenic.No acute-duration oral MRL was derivedfor monomethylarsonic acid (MMA).An MRL of 0.1 mg MMA/kg/day hasbeen derived for intermediate-durationoral exposure (15-364 days) to MMA.An MRL of 0.01 mg MMA/kg/day hasbeen derived for chronic-duration oralexposure (≥1 year) to MMA.No acute- or intermediate duration oralMRLs were derived for dimethylarsiniction oralexacid (DMA).An MRL of 0.02 mg DMA/kg/day hasbeen derived for chronic-durato DMA.posure(≥1year)