Arsenic in the Environment: Health Effects and Risk Assessment

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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 Charles O. Abernathy, Ph.D. Toxicologist, Office of Water US EPA Washington, DC Characteristics Sources Uses 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
  • 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
  • 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
  • Toxicokinetics Toxicokinetics
  • Absorption
  • Soluble forms
  • Humans – 40 % to complete absorption
  • Animals – 50% to complete absorption
  • Insoluble forms
  • Limited absorption
  • 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
  • Highest levels (ppb)
  • Nails (0.89)
  • Hair (0.18)
  • Bone (0.07 – 0.12)
  • Heart, kidney, liver, lung (0.03 – 0.05)
  • SAM SAH SAM SAH SAM SAH Metabolism of Inorganic Arsenic iAs5 Reduction Methylation iAs3 MAs5 MAs3 DMAs5 DMAs3 TMAs5 TMAs3 Excretion
  • Primarily via urine
  • 60% - 95% in 5 days
  • Fecal excretion low
  • Adverse Health Effects Non-Cancer Animal Rats Mice Guinea pigs Humans LD50 (mg/kg) 15 - 293 26 - 43 9 1 - 4 (approx) Acute Toxicity 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: HumansVascular
  • Taiwan
  • Blackfoot disease
  • Poland
  • Vintners
  • 6 cases of gangrene
  • Chile
  • Raynaud’s disease
  • Chronic Toxicity: Humans
  • Nervous system
  • Peripheral neuropathy – legs and arms
  • Cranial nerves
  • Loss of hearing in Japanese infants
  • Adverse Health Effects Cancer Countries Reporting Tumors After Arsenic Exposure
  • Taiwan
  • Mexico
  • Argentina
  • Chile
  • China
  • Mongolia
  • Japan
  • Cancers Associated with Exposure to Arsenic in Drinking Water
  • Skin
  • Bladder
  • Lung
  • Kidney
  • Liver
  • Prostate
  • 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)
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