| Literature DB >> 24260033 |
Gerry Schwalfenberg1, Stephen J Genuis, Ilia Rodushkin.
Abstract
Background. Increasing concern is evident about contamination of foodstuffs and natural health products. Methods. Common off-the-shelf varieties of black, green, white, and oolong teas sold in tea bags were used for analysis in this study. Toxic element tesass="Chemical">ting was performed on 30 different teas by analyzing (i) tea leaves, (ii) tea steeped for 3-4 minutes, and (iii) tea steeped for 15-17 minutes. Results were comass="Chemical">pared to exisEntities:
Year: 2013 PMID: 24260033 PMCID: PMC3821942 DOI: 10.1155/2013/370460
Source DB: PubMed Journal: J Toxicol ISSN: 1687-8191
Healthy minerals found in teas in this study mg/L.
| Calcium | Daily minimum requirement 800 mg | |
| 3-4 minute steeping | 1.2–8.6 | |
| 15–17 minute steeping | 1.8–12.8 | |
| Magnesium | Daily requirement | |
| 3-4 minute steeping | 2.6–14.4 | |
| 15–17 minute steeping | 3.4–16.8 | |
| Potassium | Daily requirements | |
| 3-4 minute steeping | 55–201 | |
| 15–17 minute steeping | 94–216 | |
| Phosphorus | Daily requirement of 1250 mg | |
| 3-4 minute steeping | 3.1–17.9 | |
| 15–17 minute steeping | 4.2–20.3 |
Established toxicant limits in supplements (µgm/day) adapted from [51].
| Toxic element | US California Proposition 65 (P65) and Environmental Protection Agency | European union | Australia | World Health Organization | Gestational limits |
|---|---|---|---|---|---|
| Mercury (Hg) | 2 | 4.2 | 2.4 inorganic Hg | 1.37 (methyl Hg in children) | 0.6 for methyl Hg |
| Lead | 15 | 21 | NE | 21 | Concern at low levels. 0.5 established for reproductive toxicity (P65) |
| Cadmium | 4.1 | 6 | 15 | 6 | NE |
| Arsenic | 10 | 13.0 | NE | 12.85 | NE |
| Aluminum | 7,000 | 4,286 | 12,000 | NE | NE |
NE: not established.
European/WHO/Australian levels were established by convention as representing 10% of the daily total toxicant intake after conversion of values expressed in mg/kg/week for an average adult weight of 60 kg.
Toxic element contaminants in teas.
| TEAS | Steeped 3-4 minutes | Steeped 15–17 minutes | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Average | Hg | Pb | Al | As | Cd | Hg | Pb | Al | As | Cd |
| Organic green | None detected | 1.64 | 3897 | 0.31 | 0.021 | None detected | 2.147 | 5210 | 0.39 | 0.031 |
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| Regular green | None detected | 1.37 | 2342 | 0.43 | 0.012 | None detected | 1.51 | 4798 | 0.4 | 0.02 |
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| Organic oolong | None detected | 1.96 | 5624 | 0.60 | 0.01 | None detected | 2.26 | 8808 | 0.885 | 0.014 |
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| Standard oolong | None detected | 3.05 | 4150 | 0.88 | 0.06 | None detected | 3.45 | 2876 | 0.95 | 0.065 |
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| Organic white | None detected | 1.14 | 2875 | 0.45 | 0.02 | None detected | 1.32 | 4078 | 0.56 | 0.03 |
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| Organic black | None detected | 0.78 | 5341 | 014 | None detected | None detected | 0.79 | 8096 | 0.23 | None detected |
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| Standard black | None detected | 0.86 | 4503 | 0.336 | 0.026 | None detected | 0.93 | 5261.4 | 0.28 | 0.02 |
SD is standard of deviation. None detected is below the limit of detection or <0.005 ng/L and MX is maximum level detected.
Toxicant (heavy metal) levels according to country of origin.
| Tea type | Tea country of origin | High levels | Moderate levels | Low levels |
|---|---|---|---|---|
| Green tea organic | China | Pb, Al | As | Cd |
| Green tea organic | Sri Lanka | Low in Pb, Cd, Al, As | ||
| Green tea organic | Japan | As, Pb, Cd, Al | ||
| Green tea standard | China | High in Al | Pb, As | Low in Cd |
| White tea | India | Lowest in Al, Pb, Cd, As | ||
| White tea | China | Pb, Al, As | Low in Cd | |
| Oolong tea organic | China | Highest in As, high in Pb, Al | Low in Cd | |
| Oolong tea standard | China | Highest in Pb | Al, Cd, As | |
| Black tea organic | Blend India | Al | Pb | Low in Cd, As |
| Black tea standard | India | Al | Lowest Pb, low in Cd, As |
Pb: lead, Cd: cadmium, Al: aluminum, As: arsenic.