Lead Contamination in Green Tea


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Lead Contamination in Green Tea

Postby infinite333 » Apr 15th, '12, 10:16

A colleague from China raised his concern about lead contamination when we were talking about green tea recently. After doing some reading, it looks to be linked to poor waste disposal practices and industrialization in certain regions. For example, see http://www.greenpeace.org/international/en/news/features/e-waste-china-toxic-pollution-230707/.

Studies on lead contamination in tea: http://www.sciencedirect.com/science/article/pii/S0269749105002472 http://onlinelibrary.wiley.com/doi/10.1002/jsfa.3974/abstract

My question is what can one do as a consumer to protect themself? Are there certain production regions that should be avoided? Or other areas with a better reputation? Are higher grade teas safer? Thanks.
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Re: Lead Contamination in Green Tea

Postby dnick » Apr 15th, '12, 13:18

I think the stress from worrying about this is a whole lot worse, it's just a media scare and probably even overly exaggerated, and I highly doubt -we- would be able to know where exactly our tea is sourced from most of the time and also that higher grade does not mean higher environmental/health standards.
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Re: Lead Contamination in Green Tea

Postby gingkoseto » Apr 15th, '12, 14:30

Lead contamination is a legitimate concern. Recognized sources of lead contamination includes:
* air pollution (mainly caused by automobiles and mainly affect plantations near urban areas)
* soil pollution (deposition from automobiles and mainly affect plantations by the road side)
* harvest method (bud and younger leaves are more free of contamination)
* processing - lead contamination from equipment. This is supposed to be the easiest to avoid but unfortunately happens sometimes. According to a study published in a Chinese journal, among the 18 factories whose tea products are sampled, the factories focusing on higher grade teas have the lowest lead contents, and the lead content is less after processing compared with before processing. The factories focusing on lower grade teas have the highest lead contents. I think that's consistent with common sense, as people tend to deal with high grade tea more carefully. Besides, the equipment of manually processed tea is more likely traditional and natural.

According to a Chinese article about lead standard, the Chinese tea inspection standard is 2mg/kg. Japanese standard is 25mg/kg. EU is 5mg/kg. Australia and Canada's is 10mg/kg. I don't know how accurate it is about other countries' standards and if there have been any changes since the article is from 2008. Besides, not all tea products are inspected. So it seems to me "high grade tea" and "young leaves" are the most visible standards to consumers.
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