Tea leaves pull heavy metals from water, significantly reducing the amount of lead and other dangerous compounds that people can drink unknowingly, according to a new study.
Recent research has highlighted possible applications for used tea sheets, from biofuels to gluten -free cookies. But the new study shows a benefit for public health from something that countless people are already doing. About five billion cups of tea are consumed around the world every day, according to one estimate.
“You can see the consequences,” said Vinayak Dravid, Northwestern materials scientist and author of the study, who was published this week. “How often do we touch billions of people?”
In many countries, the water used to sharp tea is infected with lead by aging. In the United States, nine million houses take their water through lead -containing pipes, according to the environmental protection service. Lead is particularly dangerous for children. The report can lead to developmental delays and behavior issues.
Dr. Dravid and his team examined how different types of tea – black, white, oolong, green, rooibos, herbs, loose leaves and simple old lipton – behaved in water with different amounts of lead.
Then the tea was allowed to go out for variable time periods. The scientists then counted how many lead in the water.
The compounds called catechins on tea leaves act like “Little Velcro” hooks, in which miles of molecules are mourn, said Michelle Francl, a chemist at Bryn Mawr College and the author of a book about tea chemistry. Dr. Francl also said that the “ridges and valleys” of tea leaves provided the surface necessary for this interaction.
While these qualities have been known for some time now, Dr. Dravid and his colleagues were the first to examine the forces to detect a cup of tea. They found that black tea leaves were crumpled after baking and thus were better equipped to absorb heavy metals.
“Green tea and black tea had quite a few equivalent amounts of metal absorbed,” said another writer Benjamin Shindel, who was a northwestern doctorate while working for the study.
White tea, on the other hand, undergoes a much milder preparation. Its leaves remain smoothly, offering less surface from which they draw heavy metals from the water. Herbal tea lovers can be frustrated to find out that chamomile tea does a bad job of heavy metal filtering, probably because it is made with chamomile flowers, not tea leaves.
Still, these distinctions between different types of tea were not the most important factor. “It’s much more important for how long you have been making tea,” Dr. Shindel said.
Researchers found that the cup of black tea for five minutes could remove 15 % of the lead from the water, which is useful but there is no “safe level” of lead exposure, according to EPA
“With lead and other pollutants, any reduction makes sense to some extent, especially if you have a shortage of resources or infrastructure that will already restore some of these problematic materials,” said Caroline Harms, who was a undergraduate student of Dr. Dravid at Northwestern while working in the study.
The longer the time of violent, the more bitter the resulting tea. Last year, Dr. Francl caused a secondary international scandal, suggesting that adding salt to tea could mitigate his bitterness. But even this controversial hack chemistry has its limits. “It is not really drinking after 10 minutes of boat tea, and no salt will help this,” he said.
Some samples in the study had to be full for 24 hours, which would make tea without exercising.
The authors of the study said they were less incentives to make public health recipes for policy -makers rather than studying a hidden benefit of a global habit.
Researchers estimate that a country where people drank large quantities of tea would have about 3 % less ingested than water supply from a (hypothetical) identical country that did not drink tea.
“How wonderful,” said Henrietta Lovell, Rare Tea Company’s founder. Ms Lovell, who supplies tea to exclusive restaurants, noted that tea had been used in China for medical purposes for thousands of years. “The more I learn about tea, the more wonderful and exciting it becomes,” Mrs Lovell said.
Dr. Francl believes that the new findings could eventually pave the way for a gradual method to make sure people do not consume heavy metals. “Since clean water is such a global issue,” he said, “if there was a way to get this proof of the concept and to bite it to produce drinking water in the end, that would be pretty good.”
