Journal of
Toxicology and Environmental Health Sciences

  • Abbreviation: J. Toxicol. Environ. Health Sci.
  • Language: English
  • ISSN: 2006-9820
  • DOI: 10.5897/JTEHS
  • Start Year: 2009
  • Published Articles: 217

Full Length Research Paper

Heavy metal contamination in Thelesperma megapotamicum

Christine Samuel-Nakamura
  • Christine Samuel-Nakamura
  • Interdepartmental Program in American Indian Studies, University of California, Los Angeles, 3220 Campbell Hall, Mailcode 154802, Los Angeles, CA 90095-1548, USA.
  • Google Scholar
Felicia S. Hodge
  • Felicia S. Hodge
  • School of Nursing, University of California, Los Angeles, 5-940 Factor Bldg., Mailcode 691921, Los Angeles, CA 90095-6919, USA.
  • Google Scholar
Jane L. Valentine
  • Jane L. Valentine
  • School of Public Health, Environmental Health Sciences, University of California, Los Angeles, 66-062 CHS., Mailcode 177220, Los Angeles, CA 90095-1772, USA.
  • Google Scholar
Wendie A. Robbins
  • Wendie A. Robbins
  • Center for Occupational and Environmental Health Fielding School of Public Health, Environmental Health Sciences, University of California, Los Angeles, 5-254 Factor Bldg., Mailcode 956919, Los Angeles, CA 90095-6919, USA.
  • Google Scholar

  •  Received: 13 January 2017
  •  Accepted: 02 February 2017
  •  Published: 31 March 2017


This study describes heavy metal (HM) contamination in the most commonly used herbal tea in several American Indian (AI) communities in northwestern New Mexico. The Navajo (Diné) reservation is located in an area that was heavily impacted by contamination associated with Uranium (U) mining that occurred from 1945 to 1988 and where more than 1,100 unreclaimed abandoned U mines and structures remain. The study objective was to establish the levels of HM contamination in this herb which is habitually and widely consumed in this reservation community.  The study aims were to: (1) describe the dietary behavior in Diné residents related to ingestion of harvested tea Thelesperma megapotamicum; (2) compare U and other HMs in tea in high and low vehicle traffic areas; and (3) disseminate study findings to the leadership and Diné community.   A descriptive comparative design was used to compare HMs in locally harvested herbs on the reservation. The plant specimens were paired with soil samples and analyzed utilizing ICP-MS.  Samples were collected from areas spanning a 3.2 km radius from the central part of abandoned uranium mines and structures. Root samples of tea had higher concentrations of HMs than above ground plant parts for As, Cd, Cs, Mo, Pb, U and V (p < 0.05). Cadmium and Mo levels were greater in high traffic versus low traffic areas (p < 0.001).  The Cd level (0.35 mg/kg) in this popular species of tea herb exceeded the World Health Organization medicinal plant maximum permissible level.  Further research and monitoring is needed to identify factors that affect HM contamination in T. megapotamicum and other plant herbs used on the Navajo reservation as well as other U mining impacted areas. 


Key words: American Indian, heavy metals, Diné/Navajo, Thelesperma megapotamicum, herbal tea, uranium, cadmium, molybdenum, mining.