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Occurrence and Risk of Metal(loid)s in Thelesperma megapotamicum Tea Plant

1
School of Nursing, University of California, Los Angeles (UCLA), 4-246 Factor Bldg., Mailcode 691821, Los Angeles, CA 90095, USA
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School of Public Health, UCLA, 5-940 Factor Bldg., Mailcode 691921, Los Angeles, CA 90095, USA
3
School of Nursing, UCLA, 5-940 Factor Bldg., Mailcode 691921, Los Angeles, CA 90095, USA
*
Author to whom correspondence should be addressed.
Plants 2020, 9(1), 21; https://doi.org/10.3390/plants9010021
Received: 2 November 2019 / Revised: 22 November 2019 / Accepted: 29 November 2019 / Published: 23 December 2019
(This article belongs to the Section Phytochemistry)
This study reports on the harvesting, ingestion, and contamination of American Indian tea Thelesperma megapotamicum grown on the Navajo Reservation in New Mexico. Uranium (U) and co-metal(loid)s (As, Cd, Cs, Mo, Pb, Se, Th, and V) have contaminated local soil and plants. Tea plants were gathered for analysis near U mining impacted areas. The study collected samples of wild tea plants (n = 14), roots (n = 14), and soil (n = 12) that were analyzed with inductively coupled plasma mass spectrometry. Tea harvesting activities, behavior, and ingestion information were collected via questionnaires. Harvesting took place in community fields and near roadways. Results indicate edible foliage concentration levels for Cd exceeded the World Health Organization (WHO) raw medicinal plant permissible level guidelines. Tea samples collected near high traffic areas had significantly greater Cd and Mo concentrations than those collected near low traffic areas (p < 0.001). Tea sample metal(loid) concentration levels ranged from 0.019–7.916 mg/kg. When compared to established food guidelines including the WHO provisional tolerable weekly intake (PTWI), reference dietary intake, recommended dietary allowance, and the tolerable upper limit (UL), Cd exceeded the WHO guidelines but none exceeded the PTWI nor the UL. These findings warrant improved standardization and establishment of universal guidelines for metal(loid) intake in food. View Full-Text
Keywords: tea; uranium; cadmium; molybdenum; Navajo; Diné; provisional tolerable weekly intake; tolerable upper limit; metal(loid)s; greenthread tea; uranium; cadmium; molybdenum; Navajo; Diné; provisional tolerable weekly intake; tolerable upper limit; metal(loid)s; greenthread
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Samuel-Nakamura, C.; Hodge, F.S. Occurrence and Risk of Metal(loid)s in Thelesperma megapotamicum Tea Plant. Plants 2020, 9, 21.

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