Tea Time!

Tea Time!


What’s Hiding in Your Tea? 


Tea plants are susceptible to a huge amount of pests and the use of pesticide preparations has become the primary means by which to combat them in the tea production process.


Recent studies have shown that tea produced in both China and India contain large amounts of pesticide residues.


When you brew your tea, the pesticide residues remaining on the tea leaves are easily transferred into your cup of tea, thereby exposing you to these hazardous chemicals.


In February 2014, a study published in the journal Toxicology investigated the presence of pesticide residues in tea produced in China. The study revealed that pesticide residues were found in the majority of tea samples taken between the years 2010 to 2012.


223 samples of green tea, pu-erh tea and oolong tea were studied for pesticide residues. 198 of these samples contained pesticide residues, with 39 having residue levels higher than the European Union (EU) maximum residue limits. 


This is concerning when you consider that China is the world’s largest tea producer, producing 1,700mkg of tea per year.


Research conducted by Greenpeace in December 2011 and January 2012 also confirmed the widespread and massive use of pesticides in tea coming from China.


Samples from nine well-known tea companies were taken with 18 different kinds of tea studied. All of the samples contained between three to ten different kinds of pesticide residues.


Similar research was conducted by Greenpeace in India where 49 brands of packaged teas were tested for pesticides.  A total of 34 pesticides were found in 46 of the brands, whilst 29 of these contained more than ten different pesticide residues.


According to Greenpeace, many of the pesticide residues have not been registered for use in the cultivation of tea. Many of the teas tested positive for monocroptophos, triazophos, tebefenpyrad and DDT which are all listed as hazardous by the World Health Organization.



How to Minimize Pesticide Residues in your Tea


In 2014 a study was published in the journal Food Chemistry which investigated the transfer of pesticide residues from green tea leaves into infused tea brew. The researchers found that the transfer of pesticides was dependent on their water solubility.


They recommended that drinking a cup of green tea should be at a water temperature of no more than 60°C (140°F) to minimise the transfer of pesticides into the tea.


Longer brewing times also resulted in an increased transfer of the pesticides into the tea.


Health Effects of Pesticide Exposure


Studies have shown that pesticide exposure may cause a range of health effects, including nervous system disorders, reproductive disorders and cancers.


Nervous system disorders reported include cognitive dysfunction such as mood changes, depression, neurodegenerative diseases and developmental effects.


Reproductive disorders result from pesticides acting as endocrine disruptors, interfering with the synthesis, secretion, transport, binding, action or elimination of natural hormones in your body, thereby altering hormonal homeostasis.


This disruption to your hormone balance can potentially lead to a range of fertility problems and birth defects.


Research has also reported links between pesticide exposure and certain cancers such as blood cancers and liver cancer.


Whilst many of these studies have been carried out on those who have been directly exposed to pesticides such as farm workers, indirect exposure to pesticide residues over a prolonged period of time may also pose a health risk to the consumer.


Tips to Avoid these Hidden Chemicals


Next time you reach for your teapot ensure you fill it with tea made from certified organic tea leaves which are free from pesticide contamination, thereby minimising the risks to your health from exposure to these nasty chemicals.


If you really can’t get hold of organic tea leaves, ensure you only use water at a maximum degree of  60°C (140°F) and don’t let your tea brew for more than a minute.


Cup of tea


For more information:

Bolton, D. (2014). India tea board responds to Greenpeace report. World Tea News, August 18, 2014.

Cho, S-K., El-Aty, A., & M. Rahman et al (2014). Simultaneous mult-determination and transfer of eight pesticide residues from green tea leaves to infusion using gas chromatography.” Food Chemistry 165, 15 December 2014, 532-539.

EU Pesticides Database

Feng, J, Tang, H., & D. Chen et al (2014).”Monitoring and risk assessment of pesticide residues in tea samples from China”. Human and Ecological Risk Assessment: An International Journal. 21 Feb 2014

Greenpeace (2012). Pesticides: Hidden ingredients in Chinese tea. pp. 1-20

Liu, X., Wenbi, G., & X. Hao et al (2014). “Pesticide multi-residue analysis in tea using d-SPE sample cleanup with graphene mixed with primary secondary amine and graphitised carbon black prior to LC-MS/MS.” Chromatographia 77(1-2), pp. 31-37.

Rama, E.M., Bortolan, S., &  Vieira, M.L.  (2014). “Reproductive and possible hormonal effects of carbendazim.” Regulatory Toxicology and Pharmacology 69(3), 476-486.

Scollon, E.J., Starr, J.M. and K.M. Crofton et al. (2011, November). “Correlation of tissue concentrations of the pyrethroid bifenthrin with neurotoxicity in the rat”. Toxicology 290(1), 1-6.

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