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Investigation of Drinking Water Exposures in Unregulated Water Sources at the Navajo Nation

Water hauling is widespread on Navajo Nation. Approximately 25% households on Navajo Nation are not connected to a public water system and must haul drinking water from outside, often untreated sources. Connected households may still choose to haul water from untreated sources. The extent to which Navajo people consume untreated water has not been quantified. The exposures and health risks associated with this practice are unknown.

As a first step in addressing this knowledge gap, The National Center for Environmental Health (NCEH) Health Studies Branch (HSB) conducted a study of 199 untreated water sources (livestock wells and springs) used for drinking water in the Navajo Nation in August 2006 and September 2007. This study showed widespread bacterial contamination and water sources exceeding EPA limits for uranium and arsenic. The study identified 5 high risk communities where water arsenic and uranium were concentrated. In order to assess the extent of human exposure to drinking water contaminants in the 5 high risk communities, HSB conducted a cross-sectional household study in October 2008.

Household Survey of Drinking Water Sources and Contaminant Exposures at the Navajo Nation

The National Center for Environmental Health (NCEH) Health Studies Branch (HSB) conducted a cross-sectional survey of 296 households (with and without access to potable water) that were randomly selected from five Navajo Nation communities. HSB interviewed one member of each household on water hauling practices, tested for urine biomarkers of exposure to 18 chemicals, and analyzed one drinking water sample for chemical and bacteria contaminants. Of 296 water samples collected, 34 (11%) samples exceeded safe drinking water standards for arsenic and 8 (3%) samples exceeded safe water standards for uranium. Ninety-two (35%) of the drinking water samples tested positive for total coliform and 22 (8%) tested positive for E. coli. Of the 244 urine samples collected, 103 (42%) had high uranium levels (>95th % of levels seen in the US population as defined by NHANES). The study population had urine levels higher than usual for national levels but comparable to other regional study levels, though none at levels known to cause health effects. Uranium contamination of water sources does not appear to be the primary cause of increased uranium levels found in urine. Bacterial contamination was found in water samples which could indicate a public health risk.

Follow-up activities included: Periodic briefings to the House Committee on Oversight and Government Reform in Washington, DC, designing and implementing a 2-day training for Navajo community health representatives, visiting each study participant in-person to discuss study results, presenting results at Chapter meetings and to community groups, preparing physician education for clinics in the study area to understand study results and potential health concerns, referring participants to the Indian Health Services’ (IHS) screening program, and labeling unsafe water sources. In October 2009, additional urine testing of participant family members will be conducted as a public service and testing all new unregulated water sources identified during the household survey.

American College of Medical Toxicology (ACMT) Navajo Nation Grand Rounds on Hazards of Uranium Tailings

The House Committee on Oversight and Government Reform requested that the Bureau of Indian Affairs (BIA), Department of Energy (DOE), Nuclear Regulatory Commission (NRC), Environmental Protection Agency (EPA), and Indian Health Service (IHS) develop a coordinated five-year plan to address the health and environmental impacts of uranium contamination in the Navajo Nation (NN). The Agency for Toxic Substances & Disease Registry (ATSDR) and the National Center for Environmental Health (NCEH) have participated in congressional briefings on this subject.

In support of the 5 agency, 5-year plan, ATSDR conducted Grand Rounds training for medical professionals at the Navajo Nation. The subject of the training was uranium exposure, but also touched on arsenic in drinking water which is of concern to the tribe. The training was conducted through the Division of Toxicology and Environmental Medicine’s (DTEM) cooperative agreement with the American College of Medical Toxicology (ACMT) and included technical input from the ASTDR Division of Health Assessment and Consultation (DHAC) and the ATSDR Division of Regional Operations (DRO). A physician with board-certification in toxicology was selected by ACMT to conduct the training which took place in December 2008 at four IHS clinics located in the Navajo communities of Tuba City, AZ; Kayenta, AZ; Chinle, AZ; and Shiprock, NM. The development of this training was an interdisciplinary effort with input from the IHS, EPA, ACMT, NCEH, Navajo Nation, University of New Mexico (UNM), Southwest Research and Information Center (SRIC), and others.

Gila River Cooperative Agreement Program

The Gila River Indian Community (GRIC) is currently the only tribal recipient of ATSDR’s Cooperative Agreement Program, which has been in place since 2001. ATSDR and GRIC have worked together to address several environmental health concerns and to minimize exposures to chemicals in the Gila River community. The GRIC program continues to build strong relationships with tribal leaders and community members through meetings and health education activities.

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