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Arsenic in the Environment: Health Effects and Risk Assessment. Charles O. Abernathy, Ph.D. Toxicologist, Office of Water US EPA Washington, DC. Characteristics Sources Uses. Arsenic Characteristics. Most natural waters contain inorganic species

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arsenic in the environment health effects and risk assessment

Arsenic in the Environment: Health Effects and Risk Assessment

Charles O. Abernathy, Ph.D.

Toxicologist, Office of Water

US EPA

Washington, DC

arsenic characteristics
Arsenic Characteristics
  • Most natural waters contain inorganic species
    • As (III) or arsenite predominant in ground waters H3AsO3
    • As (V) or arsenate in surface waters H2AsO4 & HAsO4-2
natural arsenic levels
Crystalline Rock

Soil

Ground Water

Surface Water

Avg. 2 ppm

1-40 ppm

0.01 – 800 ppb

As high as 40,000 in hot springs

2.38 – 65 ppb

As high as 22,000 in river water

Natural Arsenic Levels
some arsenic uses anthropogenic sources
Some Arsenic Uses/Anthropogenic Sources
  • Smelting of metals
  • Pharmaceutical industry (medicines)
  • Pesticide manufacture (very limited)
  • Wood preservative – CCA [in phase out]
  • Cattle and sheep dips
  • Feed additives
  • Dye stuffs
  • Petroleum, coal, and wood burning
  • Semiconductor manufacture
  • Waste incineration
toxicokinetics7
Toxicokinetics
  • Absorption
    • Soluble forms
      • Humans – 40 % to complete absorption
      • Animals – 50% to complete absorption
    • Insoluble forms
      • Limited absorption
toxicokinetics cont
Toxicokinetics cont.
  • Distribution
    • Found in all humans – Blood conc. (1-5 ppb)
      • Smokers (2 – 10 ppb)
      • Occupational exposure (10 ppb)
      • Taiwan (20 – 60 ppb)
      • Poisonings (1,000 – 2,000 ppb)
distribution
Distribution
  • Highest levels (ppb)
    • Nails (0.89)
    • Hair (0.18)
    • Bone (0.07 – 0.12)
    • Heart, kidney, liver, lung (0.03 – 0.05)
metabolism of inorganic arsenic

SAM

SAH

SAM

SAH

SAM

SAH

Metabolism of Inorganic Arsenic

iAs5

Reduction

Methylation

iAs3

MAs5

MAs3

DMAs5

DMAs3

TMAs5

TMAs3

excretion
Excretion
  • Primarily via urine
    • 60% - 95% in 5 days
  • Fecal excretion low
acute toxicity
Animal

Rats

Mice

Guinea pigs

Humans

LD50 (mg/kg)

15 - 293

26 - 43

9

1 - 4 (approx)

Acute Toxicity
acute effects humans est ld 50 1 4 mg kg
Acute Effects – Humans(est. LD50  1-4 mg/kg)
  • Peripheral neuropathy
  • Anemia
  • Renal and liver dysfunction
  • Skin pigmentation
  • EKG abnormalities
  • Severe GI effects
chronic toxicity humans vascular
Chronic Toxicity: HumansVascular
  • Taiwan
    • Blackfoot disease
  • Poland
    • Vintners
    • 6 cases of gangrene
  • Chile
    • Raynaud’s disease
chronic toxicity humans
Chronic Toxicity: Humans
  • Nervous system
    • Peripheral neuropathy – legs and arms
  • Cranial nerves
    • Loss of hearing in Japanese infants
countries reporting tumors after arsenic exposure
Countries Reporting Tumors After Arsenic Exposure
  • Taiwan
  • Mexico
  • Argentina
  • Chile
  • China
  • Mongolia
  • Japan
cancers associated with exposure to arsenic in drinking water
Cancers Associated with Exposure to Arsenic in Drinking Water
  • Skin
  • Bladder
  • Lung
  • Kidney
  • Liver
  • Prostate
lifetime risk of cancer per 1000

MCL

LED01

ED01

50

300

- - Margin of Exposure - -

(MOE)

Lifetime Risk of Cancer (per 1000)

ED01 = Effective dose (central estimate) at which 1% of population is affected by the contaminant

LED01 = Lower limit of range with 95% certainty of being the effective dose for 1%

MOE = Ratio of LED01 divided by MCL option (300/50) = 6

Point of Departure (PoD)