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 existing preferred endpoints. Results. All brewed teas contained lead with 73% of teas brewed for 3 minutes and 83% brewed for 15 minutes having lead levels considered unsafe for consumption during pregnancy and lactation. Aluminum levels were above recommended guidelines in 20% of brewed teas. No mercury was found at detectable levels in any brewed tea samples. Teas contained several beneficial elements such as magnesium, calcium, potassium, and phosphorus. Of trace minerals, only manganese levels were found to be excessive in some black teas. Conclusions. Toxic contamination by heavy metals was found in most of the teas sampled. Some tea samples are considered unsafe. There are no existing guidelines for routine testing or reporting of toxicant levels in “naturally” occurring products. Public health warnings or industry regulation might be indicated to protect consumer safety. 1. Introduction The drinking of tea has a history that likely began in China more than 3000 years ago. It has a relatively recent history in the west beginning in the 16th century when it was introduced to Portuguese priests and merchants. It became popular in Britain in the 17th century. The use of tea bags was not common until after WWII. Tea originates from the plant Camellia sinensis, a tree that may grow up to 52 feet in height unless cultivated. Tea plants require significant rainfall of 50 inches a year and grow in acidic soil. Contaminants may vary in the soil, air, or water in which the plants are grown. Acidic soil may result in excess available aluminum and fluoride [1]. An acid or alkali soil pH also enhances leaching of toxic heavy metals from the soil [2]. Increasing pH with soluble calcium would reduce the absorption of fluoride [1]. Environmental pollutants such as fluoride and aluminum have been found in tea in part due to the tea plants absorption and deposition and concentration of these compounds in the leaves [3]. The drinking of more than 5 liters of tea per week may result in dental or skeletal fluorosis [4]. Mercury, lead, arsenic, and cadmium as well as other toxic elements have been found in tea leaves as described in the literature
References
[1]
E. álvarez-Ayuso, A. Giménez, and J. C. Ballesteros, “Fluoride accumulation by plants grown in acid soils amended with flue gas desulphurisation gypsum,” Journal of Hazardous Materials, vol. 192, no. 3, pp. 1659–1666, 2011.
[2]
Z. Tan and G. Xiao, “Leaching characteristics of fly ash from Chinese medical waste incineration,” Waste Management and Research, vol. 30, no. 3, pp. 285–294, 2012.
[3]
M. Fujimaki Hayacibara, C. S. Queiroz, C. P. Machado Tabchoury, and J. Aparecido Cury, “Fluoride and aluminum in teas and tea-based beverages,” Revista de Saude Publica, vol. 38, no. 1, pp. 100–105, 2004.
[4]
S.-C. C. Lung, H.-W. Cheng, and C. B. Fu, “Potential exposure and risk of fluoride intakes from tea drinks produced in Taiwan,” Journal of Exposure Science and Environmental Epidemiology, vol. 18, no. 2, pp. 158–166, 2008.
[5]
X.-P. Wang, Y.-J. Ma, and Y.-C. Xu, “Studies on contents of arsenic, selenium, mercury and bismuth in tea samples collected from different regions by atomic fluorescence spectrometry,” Guang Pu Xue Yu Guang Pu Fen Xi, vol. 28, no. 7, pp. 1653–1657, 2008.
[6]
W.-Y. Han, F.-J. Zhao, Y.-Z. Shi, L.-F. Ma, and J.-Y. Ruan, “Scale and causes of lead contamination in Chinese tea,” Environmental Pollution, vol. 139, no. 1, pp. 125–132, 2006.
[7]
S. Shekoohiyan, M. Ghoochani, A. Mohagheghian, A. H. Mahvi, M. Yunesian, and S. Nazmara, “Determination of lead, cadmium and arsenic in infusion tea cultivated in north of Iran,” Iranian Journal of Environmental Health Science & Engineering, vol. 9, article 37, 2012.
[8]
F. Perera, T.-Y. Li, Z.-J. Zhou et al., “Benefits of reducing prenatal exposure to coal-burning pollutants to children's neurodevelopment in China,” Environmental Health Perspectives, vol. 116, no. 10, pp. 1396–1400, 2008.
[9]
D. Tang, T.-Y. Li, J. J. Liu et al., “Effects of prenatal exposure to coal-burning pollutants on children's development in China,” Environmental Health Perspectives, vol. 116, no. 5, pp. 674–679, 2008.
[10]
X.-X. Zheng, Y.-L. Xu, S.-H. Li, X.-X. Liu, R. Hui, and X.-H. Huang, “Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trials,” American Journal of Clinical Nutrition, vol. 94, no. 2, pp. 601–610, 2011.
[11]
Z.-M. Wang, B. Zhou, Y.-S. Wang et al., “Black and green tea consumption and the risk of coronary artery disease: a meta-analysis,” American Journal of Clinical Nutrition, vol. 93, no. 3, pp. 506–515, 2011.
[12]
M. Ali and M. Afzal, “A potent inhibitor of thrombin stimulated platelet thromboxane formation from unprocessed tea,” Prostaglandins Leukotrienes and Medicine, vol. 27, no. 1, pp. 9–13, 1987.
[13]
W.-S. Kang, I.-H. Lim, D.-Y. Yuk et al., “Antithrombotic activities of green tea catechins and (-)-epigallocatechin gallate,” Thrombosis Research, vol. 96, no. 3, pp. 229–237, 1999.
[14]
P. Bogdanski, J. Suliburska, M. Szulinska, M. Stepien, D. Pupek-Musialik, and A. Jablecka, “Green tea extract reduces blood pressure, inflammatory biomarkers, and oxidative stress and improves parameters associated with insulin resistance in obese, hypertensive patients,” Nutrition Research, vol. 32, pp. 421–427, 2012.
[15]
K. Boehm, F. Borrelli, E. Ernst et al., “Green tea (Camellia sinensis) for the prevention of cancer,” The Cochrane Database of Systematic Reviews, no. 3, Article ID CD005004, 2009.
[16]
B. J. Fuhrman, R. M. Pfeiffer, A. H. Wu et al., “Green tea intake is associated with urinary estrogen profiles in Japanese-American women,” Nutrition Journal, vol. 12, article 25, 2013.
[17]
J. A. Montague, L. M. Butler, A. H. Wu, et al., “Green and black tea intake in relation to prostate cancer risk among Singapore Chinese,” Cancer Causes Control, vol. 23, pp. 1635–1641, 2012.
[18]
J. S. Zheng, J. Yang, Y. Q. Fu, T. Huang, Y. J. Huang, and D. Li, “Effects of green tea, black tea, and coffee consumption on the risk of esophageal cancer: a systematic review and meta-analysis of observational studies,” Nutrition and Cancer, vol. 65, no. 1, pp. 1–16, 2013.
[19]
T. M. Jurgens, A. M. Whelan, L. Killian, S. Doucette, S. Kirk, and E. Foy, “Green tea for weight loss and weight maintenance in overweight or obese adults,” The Cochrane Database of Systematic Reviews, vol. 12, Article ID 008650, 2012.
[20]
M. Maeda-Yamamoto, “Human clinical studies of tea polyphenols in allergy or life style-related diseases,” Current Pharmaceutical Design, vol. 19, no. 34, pp. 6148–6155, 2013.
[21]
J. Yan, Y. Zhao, S. Suo, Y. Liu, and B. Zhao, “Green tea catechins ameliorate adipose insulin resistance by improving oxidative stress,” Free Radical Biology and Medicine, vol. 52, no. 9, pp. 1648–1657, 2012.
[22]
K. C. Silva, M. A. Rosales, D. E. Hamassaki, et al., “Green tea is neuroprotective in diabetic retinopathy,” Investigative Ophthalmology & Visual Science, vol. 54, pp. 1325–1336, 2013.
[23]
M.-Y. Kang, Y. H. Park, B. S. Kim et al., “Preventive effects of green tea (Camellia Sinensis var. Assamica) on diabetic nephropathy,” Yonsei Medical Journal, vol. 53, no. 1, pp. 138–144, 2012.
[24]
A. Araghizadeh, J. Kohanteb, and M. M. Fani, “Inhibitory activity of green tea (Camellia sinensis) extract on some clinically isolated cariogenic and periodontopathic bacteria,” Medical Principles and Practice, vol. 22, no. 4, pp. 368–372, 2013.
[25]
J. Steinmann, J. Buer, T. Pietschmann, and E. Steinmann, “Anti-infective properties of epigallocatechin-3-gallate (EGCG), a component of green tea,” British Journal of Pharmacology, vol. 168, pp. 1059–1073, 2013.
[26]
R. Canuel, S. B. de Grosbois, M. Lucotte, L. Atikessé, C. Larose, and I. Rheault, “New evidence on the effects of tea on mercury metabolism in humans,” Archives of Environmental and Occupational Health, vol. 61, no. 5, pp. 232–238, 2006.
[27]
M. He and W.-X. Wang, “Factors affecting the bioaccessibility of methylmercury in several marine fish species,” Journal of Agricultural and Food Chemistry, vol. 59, no. 13, pp. 7155–7162, 2011.
[28]
W. Liu, Z. Xu, H. Yang, Y. Deng, B. Xu, and Y. Wei, “The protective effects of tea polyphenols and schisandrin B on nephrotoxicity of mercury,” Biological Trace Element Research, vol. 143, no. 3, pp. 1651–1665, 2011.
[29]
O. Ouédraogo and M. Amyot, “Effects of various cooking methods and food components on bioaccessibility of mercury from fish,” Environmental Research, vol. 111, no. 8, pp. 1064–1069, 2011.
[30]
“Tea and coffee with your fish?” Harvard Health Letter, vol. 37, no. 3, article 7, 2012.
[31]
N. M. Pham, A. Nanri, K. Kurotani et al., “Green tea and coffee consumption is inversely associated with depressive symptoms in a Japanese working population,” Public Health Nutrition, 2013.
[32]
K. Niu, A. Hozawa, S. Kuriyama et al., “Green tea consumption is associated with depressive symptoms in the elderly,” American Journal of Clinical Nutrition, vol. 90, no. 6, pp. 1615–1622, 2009.
[33]
S. Davinelli, N. Sapere, D. Zella, R. Bracale, M. Intrieri, and G. Scapagnini, “Pleiotropic protective effects of phytochemicals in Alzheimer's disease,” Oxidative Medicine and Cellular Longevity, vol. 2012, Article ID 386527, 11 pages, 2012.
[34]
World Health Organization, “Global assessment of the state-of-the-science of endocrine disruptors,” Geneva, Switzerland, pp. 1–180, 2002.
[35]
Y. W. Chen, C. F. Huang, C. Y. Yang, C. C. Yen, K. S. Tsai, and S. H. Liu, “Inorganic mercury causes pancreatic β-cell death via the oxidative stress-induced apoptotic and necrotic pathways,” Toxicology and Applied Pharmacology, vol. 243, no. 3, pp. 323–331, 2010.
[36]
E. A. Belyaeva, T. V. Sokolova, L. V. Emelyanova, and I. O. Zakharova, “Mitochondrial electron transport chain in heavy metal-induced neurotoxicity: effects of cadmium, mercury, and copper,” The Scientific World Journal, vol. 2012, Article ID 136063, 14 pages, 2012.
[37]
L. Hu, J. B. Greer, H. Solo-Gabriele, L. A. Fieber, and Y. Cai, “Arsenic toxicity in the human nerve cell line SK-N-SH in the presence of chromium and copper,” Chemosphere, vol. 91, no. 8, pp. 1082–1087, 2013.
[38]
M. Valko, H. Morris, and M. T. D. Cronin, “Metals, toxicity and oxidative stress,” Current Medicinal Chemistry, vol. 12, no. 10, pp. 1161–1208, 2005.
[39]
A. R. Nair, O. Degheselle, K. Smeets, E. Van Kerkhove, and A. Cuypers, “Cadmium-induced pathologies: where is the oxidative balance lost (or not)?” International Journal of Molecular Sciences, vol. 14, no. 3, pp. 6116–6143, 2013.
[40]
N. F. Kolachi, T. G. Kazi, H. I. Afridi et al., “Status of toxic metals in biological samples of diabetic mothers and their neonates,” Biological Trace Element Research, vol. 143, no. 1, pp. 196–212, 2011.
[41]
K. Jomova, D. Vondrakova, M. Lawson, and M. Valko, “Metals, oxidative stress and neurodegenerative disorders,” Molecular and Cellular Biochemistry, vol. 345, no. 1-2, pp. 91–104, 2010.
[42]
S. J. Genuis, “Sensitivity-related illness: the escalating pandemic of allergy, food intolerance and chemical sensitivity,” The Science of the Total Environment, vol. 408, no. 24, pp. 6047–6061, 2010.
[43]
P. Moszczyński, J. Rutowski, S. S？owiński, and S. Bem, “Immunological effects of occupational exposure to metallic mercury in the population of T-cells and NK-cells,” Analyst, vol. 123, no. 1, pp. 99–103, 1998.
[44]
C. Guerrero-Bosagna and M. K. Skinner, “Environmentally induced epigenetic transgenerational inheritance of phenotype and disease,” Molecular and Cellular Endocrinology, vol. 354, no. 1-2, pp. 3–8, 2012.
[45]
M. K. Skinner, “Role of epigenetics in developmental biology and transgenerational inheritance,” Birth Defects Research C, vol. 93, no. 1, pp. 51–55, 2011.
[46]
M. E. Sears, K. J. Kerr, and R. I. Bray, “Arsenic, cadmium, lead, and mercury in sweat: a systematic review,” Journal of Environmental and Public Health, vol. 2012, Article ID 184745, 10 pages, 2012.
[47]
M. E. Sears and S. J. Genuis, “Environmental determinants of chronic disease and medical approaches: recognition, avoidance, supportive therapy, and detoxification,” Journal of Environmental and Public Health, vol. 2012, Article ID 356798, 15 pages, 2012.
[48]
S. J. Genuis, “Elimination of persistent toxicants from the human body,” Human and Experimental Toxicology, vol. 30, no. 1, pp. 3–18, 2011.
[49]
T. W. Clarkson, “Factors involved in heavy metal poisoning,” Federation Proceedings, vol. 36, no. 5, pp. 1634–1639, 1977.
[50]
T. I. Lidsky and J. S. Schneider, “Lead neurotoxicity in children: basic mechanisms and clinical correlates,” Brain, vol. 126, no. 1, pp. 5–19, 2003.
[51]
S. J. Genuis, G. Schwalfenberg, A. K. Siy, and I. Rodushkin, “Toxic element contamination of natural health products and pharmaceutical preparations,” PLoS One, vol. 7, no. 11, Article ID e49676, 2012.
[52]
M. A. Rahman, B. Rahman, and N. Ahmed, “High blood manganese in iron-deficient children in Karachi,” Public Health Nutrition, vol. 16, no. 9, pp. 1677–1683, 2013.
[53]
F. M. Crinella, “Does soy-based infant formula cause ADHD? Update and public policy considerations,” Expert Review of Neurotherapeutics, vol. 12, no. 4, pp. 395–407, 2012.
[54]
Y. Wang, H. Jing, V. Mehta, G. J. Welter, and D. E. Giammar, “Impact of galvanic corrosion on lead release from aged lead service lines,” Water Research, vol. 46, pp. 5049–5060, 2012.
[55]
R. W. Sheets, “Release of heavy metals from European and Asian porcelain dinnerware,” The Science of the Total Environment, vol. 212, no. 2-3, pp. 107–113, 1998.
[56]
Centers for Disease Control, Department of Health and Human Services, “Fourth National Report on Human Exposure to Environmental Chemicals,” Atlanta, Ga, USA, pp.1–529, 2009, http://www.cdc.gov/exposurereport/pdf/FourthReport.pdf.
[57]
World Health Organization, “Children's Health and the Environment. WHO Training Package for the Health Sector,” World Health Organization, 2009, http://www.who.int/ceh/en/.
[58]
D. Coury, “Biological influences on brain and behavior,” in Proceedings of the Pediatric Academic Societies' Annual Meeting: Adolescent Medicine, Baltimore, Md, USA, 2001.
