re: heavy metals
This study is difficult to interpret, and done by scientists apparently intent on making it difficult to understand the risks of drinking green tea as it is actually done. Scientists like this suck; they are not trying very hard for societal usefulness.
Assessment of the mineral composition of green tea is helpful to estimate the intake of toxic metals and bioelements associated with the consumption of infusions. Based on the FAO/WHO recommendations, we showed that consumption of green tea from China, Japan, India, and marketed tea is not associated with health hazards related to exposure to heavy metals such as Cd. Consumption of five cups of green tea per week does not pose a risk to human health. Comparison with the recent standards showed that green tea is characterized by high Mn levels...
WIND: conclusion sections are risky; you must read the study.
Some teas are high in lead, some low, and it’s impossible to know since no one one will test them for you unles syou find a competent lab and pay for it.
The conclusions do not seem supportable: at least one tea had 0.84mg Pb per 100g tea, which is 840 mcg per 100g tea— a huge amount. A double serving size (typical for me) is 6g. That equates to 840*(6/100) = 50 mcg Pb per serving?! Or about 100X higher than the California limit for pregnant women!
The study methodology does not make of the actual amount in the brewed tea as it is actually brewed; it speaks of leaching of Pb at 12.6% of the lead content, which would imply 0.126 * 50 = 6.3 mcg, which is still 12X the California limit of 0.5 mcg for pregnant women. No one in their right mind could call that anything but slow poisoning since it would just be two servings of tea per day.
Japanese tea had the highest Pb contamination (0.84 mg/100 g) and the percentage of leaching of this heavy metal amounted to 12.6 % (Table (Table3).3). Few studies have assessed the concentration of Pb in tea infusions. Jin et al. (2005) observed a restricted leaching of Pb from tea leaves during soaking in boiling water. Karak and Bhagat (2010) suggested that there is a risk of exceeding the World Health Organization (WHO) limit set for Pb in drinking water (0.05 mg/L) by tea infusions (WHO 2003). Therefore, the contamination of tea leaves by Pb remains an issue of concern, and practices should be developed to avoid problems in the future.
If the WHO think 50mcg lead (Pb) per liter of lead in drinking water is the acceptable limit, they are grossly incompetent to tell us anything about health—that’s 100X the California limit for a pregnant woman—in just 1L of water—insanity.
As with most studies, the “wet noodle” statements at the end are idiotically useless NPC boilerplate: “practices should be developed to avoid problems in the future”. Yeah, and wipe your ass after taking a shit too—so helpful.