1 / 20

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. Characteristics Sources Uses. Arsenic Characteristics. Most natural waters contain inorganic species

geordi
Download Presentation

Arsenic in the Environment: Health Effects and Risk Assessment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Arsenic in the Environment: Health Effects and Risk Assessment Charles O. Abernathy, Ph.D. Toxicologist, Office of Water US EPA Washington, DC

  2. Characteristics Sources Uses

  3. 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

  4. 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

  5. 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

  6. Toxicokinetics

  7. Toxicokinetics • Absorption • Soluble forms • Humans – 40 % to complete absorption • Animals – 50% to complete absorption • Insoluble forms • Limited absorption

  8. 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)

  9. Distribution • Highest levels (ppb) • Nails (0.89) • Hair (0.18) • Bone (0.07 – 0.12) • Heart, kidney, liver, lung (0.03 – 0.05)

  10. SAM SAH SAM SAH SAM SAH Metabolism of Inorganic Arsenic iAs5 Reduction Methylation iAs3 MAs5 MAs3 DMAs5 DMAs3 TMAs5 TMAs3

  11. Excretion • Primarily via urine • 60% - 95% in 5 days • Fecal excretion low

  12. Adverse Health Effects Non-Cancer

  13. Animal Rats Mice Guinea pigs Humans LD50 (mg/kg) 15 - 293 26 - 43 9 1 - 4 (approx) Acute Toxicity

  14. Acute Effects – Humans(est. LD50  1-4 mg/kg) • Peripheral neuropathy • Anemia • Renal and liver dysfunction • Skin pigmentation • EKG abnormalities • Severe GI effects

  15. Chronic Toxicity: HumansVascular • Taiwan • Blackfoot disease • Poland • Vintners • 6 cases of gangrene • Chile • Raynaud’s disease

  16. Chronic Toxicity: Humans • Nervous system • Peripheral neuropathy – legs and arms • Cranial nerves • Loss of hearing in Japanese infants

  17. Adverse Health Effects Cancer

  18. Countries Reporting Tumors After Arsenic Exposure • Taiwan • Mexico • Argentina • Chile • China • Mongolia • Japan

  19. Cancers Associated with Exposure to Arsenic in Drinking Water • Skin • Bladder • Lung • Kidney • Liver • Prostate

  20. 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)

More Related