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

Prevalence of Arsenic and Some Background

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.

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

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

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 for inorganic compounds: – 44 (22%) exceeded one or more of the primary drinking water standards. – The most frequent exceedance was arsenic (24 [12%] sources) followed by uranium (9 [5%] sources). The highest arsenic level was 190ug/L

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

Hazard Identification

Water Soluble Arsenic Species

Organic Arsenic Less toxic than inorganic As Produced by biomethylation Organisms in soil and water Humans (detoxify organic As)

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.

Toxicokinetics

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

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

As 5+ (Arsenate) As 3+ (Arsenite) Methylarsenite (liver) Dimethylarsenite (readily eliminated – urine) Metabolism of Inorganic Arsenic Ar undergoes methylation to less toxic metabolites

Excretion Half-life= 3-5 days Primarily via urine – 60% - 95% in 5 days

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.

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.

Exposure Assessment

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

Exposure among 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.

Ar Concentrations Measured in Diné Communities CommunityConcentration of Arsenic (mg/L) Sweetwater (09T-592)0.026 Red Mesa (9T-538)0.05 Lower Greasewood0.17 A lot of communities~0.02

Standards for Arsenic in Drinking Water AgencyLevelComments World Health Organization (WHO) 0.01mg/L is the allowable concentration Inorganic arsenic is a documented human carcinogen. Environmental Protection Agency (EPA) mg/ml is the maximum contaminant level -- zero mg/ml is the MCLG -- RfD=0.3 ug/kg/day EPA’s stated policy in setting MCLs for known human carcinogens has the goal of ensuring that the MCL falls within the 1: 10,000 to 1: million range

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

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

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.

Precautionary Assessment Community/Social Issues Exposure Issues Hazard/Toxicity

Precautionary Assessment Community/Social Issues ParameterScore Goal2 Need3 Future Generations3 Democratic Community Based Process2 Alternatives3 Total13/15 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

Precautionary Assessment Exposure Issues ParameterScore Exposure3 Multiple Exposures3 Children Exposed5 Consumer Products (Sheep Meat)2 Occupational Exposure1 Food Exposure2 Total16/20 Note: Please see end of presentation for more detailed information about Evaluation Scores A score of 16 suggests that there is an exposure problem that presents concerns to the community

Precautionary Assessment Hazard/Toxicity ParametersScore Hazard10 Individual Sensitivity3 Ecological Hazard2 Volume5 Persistent3 Bioaccumulate1 Uncertainty3 Total27/30 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

Conclusions Exposure Assessment – Ingestion= mg/kg/day – EPA RfD= 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

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

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

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

References NRDC – EPA – l l Toxmetal – projects/Arsenic.html projects/Arsenic.html

Precautionary Assessment Community / Social Issues Community / Social Issues Score Evaluate effects on the community and related social issues. Goal1-3 1-a lot, 2-some, 3-little. Does this move forward the goal of human and environmental health? Need1-3 1-a lot, 2-some, 3-little or not sure. Ask the question: Is it necessary? Do we really need this? Future Generations1-3 1-little, 2-some, 3-high impact. Is there a potential impact on future generations of humans and other species? Democratic, community based process1-3 1-a lot of community involvement and consultation, 2-some, 3-little. Was the community consulted early and often in the process? Was the process democratic and inclusive. Alternatives1-3 1-alternatives were carefully considered, 2-some consideration, 3-no consideration. Where alternatives considered? Total good, supportive of health and community 15-poor, not supportive of health or community

Precautionary Assessment Exposure Exposure IssuesScore Evaluate Potential Exposure Issues Exposure0-3 0-none, 1-little, 2-some, 3-high. Do we have control over the exposure? Multiple exposures0-3 0-none, 1-little, 2-some, 3-high. Is there exposure to other chemicals with similar hazard? Children exposed0,3,5 0-none, 3-little, 5-some or high or don't know. Children are often more vulnerable. Are children being exposed. Consumer products0-3 0-not in consumer products, 1-little, 2-some, 3- a lot or do not know. Is this compound in consumer products? Occupational exposure0-3 0-no occupational exposure, 1-little, 2-some, 3- a lot or do not know. Is there occupational exposure? Food exposure0-3 0-not in food supply, 1-little, 2-some, 3- a lot or do not know. Is the compound present in the food supply. Total no exposure, no problems 20-significant exposure, serious concern

Precautionary Assessment Hazard / Toxicity ScoreEvaluate Potential Hazards Hazard1,5,10 1-low, 5-some, 10-high. Follow classical hazard evaluation, pick endpoint, exam relevant quality studies (cancer, reproductive, neurotoxicity, irreversible) Individual Sensitivity1-3 1-little 2-some, 3-a lot. Determine if any individuals are more sensitive than health adult such as the very young or old. Ecological hazard1-3 1-little 2-some, 3-a lot. Is it a hazard to other species or the environment? Volume1-5 how much is produced (1=research only, 2= 100,000 or do not know) Persistent1-3 1-little persistence 2-some, 3-a lot of persistence or do not know. Is the compound persistent in the environment? Bioaccumulate1-3 1-little 2-some, 3-a lot. Does it bioaccumulative in humans or animals or move up the food chain? Uncertainty1-31-little 2-some, 3-a lot. How certain is the information? Total low hazard 30-significant hazards or unknowns, serious concern