Pesticides and tea

A couple of days ago some friends dropped by, along with a friend of theirs. I offered friend-of-a-friend a cup of tea, and the exchange went something like:

FOAF: "What brand is it? "
Me: "Nerada."
FOAF: "Never heard of it! "
Me: "It's pesticide-free and Australian grown; I try to buy local organic foods."
FOAF: "Ugh, organic tea is awful. "
Me: "Yeah well, Choice Magazine did some testing a few years ago and found one or more of around 20 different pesticide residues in 40% of the teas they tested, so I'd rather not drink the conventional stuff."
FOAF: "Well, I'll just have to get cancer then, because I'm not drinking that stuff. Hahahahahahah [laughs uproariously]."

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While I find that sort of behaviour bizarre, unfortunately it isn't uncommon :-( I suspect because science hasn't yet been able to provide a definitive list of diseases caused by pesticides and herbicides - just vague recommendations or assurances based on studies done on mice - that many people don't take pesticides as a serious threat? Instead, we are just considered "unlucky" if we happen to develop some sort of cancer, and it is only occasionally spoken about in hushed conversation if it might be linked to something poisonous, like the youngish neighbour-of-a-relative who died of a particularly aggressive cancer shortly after crawling around underneath his house spraying around left-over agricultural pesticides to kill off the spiders.


The two largest tea-producing regions in the world are China and India (read what you like into that statement), and whilst their tea leaves must remain below the MRLs or Maximum Residue Limits for pesticides if they are sold on the international market, the MRLs were, in most instances, set many years ago before concerns about long-term pesticide exposure were raised. And from an ethical viewpoint, I also have grave concerns for the welfare of the workers using these chemicals, particularly in regions that may not have as stringent health and safety regulations as we do here in Australia.


The pesticides used on tea plants generally fall into three groups; organochlorines, organophosphates and pyrethrins.


Organochlorine pesticides (of which, DDT is one) may be "endocrine disruptors", that is, they affect the hormone systems of animals, including fish, birds and humans. They are also stored in fat cells and breast tissue in mammals, and have been shown to be passed on through breast milk. Studies on mice have shown links to breast cancer.


Organophosphates (which include the active ingredients in most commercial head lice preparations) kill insects by disrupting their brains and nervous systems, and unfortunately they also affect the brain and nervous systems of animals that come into contact with them as well, although the effect will be determined by the particular chemical, the dose, exposure time and method of exposure.


Pyrethrins are naturally-occurring insecticides originally extracted from chrysanthemum flowers, and are found in numerous household sprays: pet shampoos and treatments, "natural" head lice treatments, mosquito repellents etc. They work by interfering with the function of the brain and nervous systems. There is (as yet) no evidence of them causing cancer in humans, but short-term effects to high exposure in the air, food or water can include dizziness, headache, nausea, muscle twitching and reduced energy, or changes in awareness, convulsions and loss of consciousness with very high levels.


It is also worth noting that studies have only been done on the individual chemicals, not the usual combination of chemicals you might find in conventional farming practices.


It's not surprising however, that Twinings', one of the largest tea manufacturers in the world, view on the matter is: "We believe that pesticide residues in tea provide an insignificant contribution to pesticide intake from dietary sources."


Yes, but why drink any if you don't have to?


Choice Magazine survey