Ground water contamination with 238U, 234U, 235U, 226Ra and 210Pb from past uranium mining: cove wash, Arizona

Abstract

The objectives of the study are to present a critical review of the (238)U, (234)U, (235)U, (226)Ra and (210)Pb levels in water samples from the EPA studies (U.S. EPA in Abandoned uranium mines and the Navajo Nation: Red Valley chapter screening assessment report. Region 9 Superfund Program, San Francisco, 2004, Abandoned uranium mines and the Navajo Nation: Northern aum region screening assessment report. Region 9 Superfund Program, San Francisco, 2006, Health and environmental impacts of uranium contamination, 5-year plan. Region 9 Superfund Program, San Franciso, 2008) and the dose assessment for the population due to ingestion of water containing (238)U and (234)U. The water quality data were taken from Sect. "Data analysis" of the published report, titled Abandoned Uranium Mines Project Arizona, New Mexico, Utah-Navajo Lands 1994-2000, Project Atlas. Total uranium concentration was above the maximum concentration level for drinking water (7.410-1 Bq/L) in 19 % of the water samples, while (238)U and (234)U concentrations were above in 14 and 17 % of the water samples, respectively. (226)Ra and (210)Pb concentrations in water samples were in the range of 3.7 × 10(-1) to 5.55 × 102 Bq/L and 1.11 to 4.33 × 102 Bq/L, respectively. For only two samples, the (226)Ra concentrations exceeded the MCL for total Ra for drinking water (0.185 Bq/L). However, the (210)Pb/(226)Ra ratios varied from 0.11 to 47.00, and ratios above 1.00 were observed in 71 % of the samples. Secular equilibrium of the natural uranium series was not observed in the data record for most of the water samples. Moreover, the (235)U/(total)U mass ratios ranged from 0.06 to 5.9 %, and the natural mass ratio of (235)U to (total)U (0.72 %) was observed in only 16 % of the water samples, ratios above or below the natural ratio could not be explained based on data reported by U.S. EPA. In addition, statistical evaluations showed no correlations among the distribution of the radionuclide concentrations in the majority of the water samples, indicating more than one source of contamination could contribute to the sampled sources. The effective doses due to ingestion of the minimum uranium concentrations in water samples exceed the average dose considering inhalation and ingestion of regular diet for other populations around the world (1 μSv/year). The maximum doses due to ingestion of (238)U or (234)U were above the international limit for effective dose for members of the public (1 mSv/year), except for inhabitants of two chapters. The highest effective dose was estimated for inhabitants of Cove, and it was almost 20 times the international limit for members of the public. These results indicate that ingestion of water from some of the sampled sources poses health risks.

Incidence and prevalence of Parkinson's disease among Navajo people living in the Navajo nation

“…Until approximately 1970, sheep were bathed in pesticide solutions containing organophosphates, a process known as sheep dipping that has been linked to high human exposures and neurological injury . Unidentified risks for PD also may be present in the Navajo Nation, such as exposure to metals through work in mines or drinking contaminated water …”

“…35 Unidentified risks for PD also may be present in the Navajo Nation, such as exposure to metals through work in mines or drinking contaminated water. 36 Varying incidence according to race could also support an evolved genetic risk since the arrival of American Indians in North America. Parkinson's disease is acknowledged to have genetic influences that vary according to ethnic background.…”

Quantification of Elemental Contaminants in Unregulated Water across Western Navajo Nation

“…Though uranium mining ceased on the Navajo Nation in 1986, the contamination left from these operations still represents a significant danger to the Navajo people [16,19]. Unregulated “Livestock Only” water sources found across the Navajo Nation are susceptible to contamination from previous mining operations, and their unregulated nature can result in an exceedance of various United States Environmental Protection Agency (EPA) Maximum Contamination Levels (MCL) [20,21,22,23]. These unregulated water sources often represent the most convenient source of water for human consumption, household use, and watering crops for families and communities across the Navajo Nation.…”

Unexpected Lack of Deleterious Effects of Uranium on Physiological Systems following a Chronic Oral Intake in Adult Rat

“…This study was performed in rats of a wide range of concentrations (0.2, 2, 5, 10, 20, 40, or 120 mg/L) of uranium in drinking water. These uranium levels include the uranium level of 0.2 mg/L close to values measured around mining areas [ 28 ], the uranium level of 1 mg/L close to the concentration of 0.96 mg/L that served to determine the previous WHO guideline of uranium level in drinking water [ 3 ], and the maximal concentration measured throughout the world (20 mg/L in Finland [ 29 ]). Duration of 9 months was chosen for the present study to mimic the chronic exposure of populations living on uranium-rich territories and to evaluate its long-term consequences.…”