| 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 testing 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 compared 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.