1. Arsenic in Livestock Well Water onthe Diné Reservation Clarita Lefthand, Ph.D. Student University of Washington Some Data presented here was obtained from the Navajo EPA

2. Prevalence of Arsenic and Some Background

3. Naturally occurring element in bedrock • They have no smell, and most have no taste. • Difficult to tell if arsenic is present in food, water, or air.

4. Anthropogenic Sources • Smelting of metals • Pharmaceutical industry (medicines) • Pesticide manufacture (very limited) • Wood preservative • Cattle and sheep dips • Petroleum, coal, and wood burning • Waste incineration

5. Counties with arsenic concentrations exceeding MCL in 10% or more groundwater samples.

6. Some Current Sampling Data • Of 188 water sources tested for bacteria: • 40 (21%) were positive for E. coli and • 144 (77%) were positive for total coliforms. • Of 199 sources tested forinorganic compounds: • 44 (22%) exceeded one or more of the primary drinking water standards. • The most frequent exceedancewas arsenic (24 [12%] sources) followed by uranium (9 [5%] sources). The highest arsenic level was 190ug/L

7. Livestock Well 30% Did Not Specify 37% Livestock Well Chapter House Natural Spring Did Not Specify or “Other” Chapter House Natural Spring 22% 11% Hauled Drinking Water Sources • Nresponses= 94 (Ntotal=296) • Multiple sources could be used by same individual

10. Hazard Identification

11. Water Soluble Arsenic Species

12. Organic Arsenic • Less toxic than inorganic As • Produced bybiomethylation • Organisms in soil and water • Humans (detoxify organic As)

13. Mode of Action • Cancer: • The most accepted explanation of the mode of action for Ar carcinogenicity is that it induces chromosomal abnormalities without interacting directly with DNA. • Noncancer: • Ar has inhibitory effects cellular respiration at the level of the mitochondrion. • Oxidative stress might also have an important role in both cancer and noncancer effects.

14. Toxicokinetics

15. Absorption • Absorption • Soluble forms are well absorbed in the GIT by humans • 60%-90% • Animals – 50% • Insoluble forms • Limited absorption

16. Distribution • After absorption Ar initially accumulates in the • Nails • Hair • Bone • Kidney, liver, lung • Binds to sulfhydryl containing proteins - concentrates in the hair and fingernails

17. Metabolism of Inorganic Arsenic Ar undergoes methylation to less toxic metabolites As5+ (Arsenate) As3+ (Arsenite) Methylarsenite(liver) Dimethylarsenite (readily eliminated – urine)

18. Excretion • Half-life= 3-5 days • Primarily via urine • 60% - 95% in 5 days

19. Health Effects of Chronic Ingestion Cancers: Bladder, kidney, liver and skin cancers: drinking water Lung cancer caused from inhalation Non-Cancer Endpoints: Blackfoot disease Increases a person’s risk of vascular and heart disease, type 2 diabetes, reproductive and developmental disorders, low birth weights in babies, neurological problems and lower IQ’s in children. neurological, renal, cardiovascular, hematological, and testicular effects.

20. Epidemiology Studies • Taiwan: The most studied area • Chile: • Argentina: • In these studies chronic exposure was determined to cause bladder, lung and skin cancer • [Ar] were several hundred micrograms per liter • EPA cancer risk assessment has used the cancer data from SW Taiwan (primarily bladder cancer cases in the Blackfoot-Disease endemic area) to predict the cancer risk from arsenic in drinking water in the USA.

21. Exposure Assessment

22. Routes of Exposure • Ingestion – The most important route of exposure because it does the most damage • Skin Contact – Also a very important route of exposure • Inhalation– A minor pathway of exposure

23. Exposureamong Diné Communities • In this assessment we are primarily concerned with ingestion of Ar • Current data suggest that exposure occurs mainly from the ingestion of arsenic through contaminated livestock well water • Adverse health effects depend on dose, duration of exposure, and the nutritional state of exposed populations. • In the case of the Diné community, chronic exposure is of concern.

24. Ar Concentrations Measured in Diné Communities

25. Standards for Arsenic in Drinking Water

26. Exposure Assessment • Ingestion (mg/kg/day) =(C*IR*ED*EF) BW*AT • C: Concentration = 0.17 mg/L • IR: Ingestion Rate =0.927L/day • ED:Exposure Duration = 75 yr • EF: Exposure Frequency= 365 days/yr • BW: Body Weight= 70 kg • AT:Averaging time= 75 yr*365 day=27,375 d

27. Exposure Assessment • Ingestion =0.17 mg/L*0.927L/day = 70 kg • Ingestion= 0.0023 mg/kg/day • EPA RfD=0.3 ug/kg/day=0.0003 mg/kg/day • The average adult person’s exposure is 8 times higher than the EPA’s RfD.

28. Exposure Assessment Limitations • Other exposure questions that must be address include: • Is exposure from food ingestion possible? • Arsenic may also be released into the atmosphere from coal-fired power plants and incinerators because coal and waste products often contain some arsenic • Soil consumption by children • Moreover what about children’s or pregnant mother’s Dose? • Adverse health effects depend on dose, duration of exposure, and the nutritional state of exposed populations.

30. Precautionary Assessment • Community/Social Issues • Exposure Issues • Hazard/Toxicity

31. Precautionary AssessmentCommunity/Social Issues A score of 13 suggests that at present there is very little support for health or community Note: Please see end of presentation for more detailed information about Evaluation Scores

32. Precautionary AssessmentExposure Issues A score of 16 suggests that there is an exposure problem that presents concerns to the community Note: Please see end of presentation for more detailed information about Evaluation Scores

33. Precautionary AssessmentHazard/Toxicity A score of 27 suggest that there is a significant hazard that present a serious concern Note: Please see end of presentation for more detailed information about Evaluation Scores

34. Conclusions • Exposure Assessment • Ingestion= 0.0023 mg/kg/day • EPA RfD=0.0003 mg/kg/day • The average adult person’s exposure is 8 times higher than the EPA’s RfD. • Precautionary Assessment • Community and Social Issues: 13/15 • Exposure Issues: 16/20 • Hazard and Toxicity: 27/30

35. Risk Management • Continue to monitor and sample for all the livestock wells. • It would be useful to have a better understanding about other exposures: • i.e., Sheep meat, soil ingestion, and air contamination • Determine long-term strategies for for drinking water issues including those that extend beyond arsenic contamination • For example: Fecal Coliform and Uranium; and lack of drinking water for future

36. Risk Management • Remediation • Whole house: 200 gallons water/day • Point of use: daily consumption of water

37. Risk Communication • Help educate the community who are directly impacted by contaminated water about their potential exposure to Arsenic • Inform the community in a culturally appropriate way • Continue and encourage community involvement in the decision making process to clean up the well water or to find alternative water sources that are viable for the community

38. References • NRDC • http://www.nrdc.org/water/drinking/qarsenic.asp • EPA • http://www.epa.gov/safewater/arsenic/index.html • Toxmetal • http://www.dartmouth.edu/~toxmetal/research/projects/Arsenic.html

39. Precautionary AssessmentCommunity / Social Issues

40. Precautionary AssessmentExposure

41. Precautionary Assessment